JPH06144259A - Rear wheel steering system - Google Patents

Abstract

(57) [Summary] [Purpose] To enable the rear wheels to return to the neutral position even when the control unit is abnormal, without using the return spring. A rear wheel steering mechanism 11 controlled by motors 12, M1, M2, motor drivers 5, 6 for rotating the motors, first microprocessors 1, 1 connected to motor drivers via relays 7, 8. The second microprocessor 2 that performs the same calculation as that of the first microprocessor and the backup microprocessor 3 that can control the motor driver via the relays 7 and 8 are provided. Abnormalities are judged by mutual comparison, and at the time of abnormality, the backup microprocessor 3 steers the rear wheel steering mechanism 11 to return the rear wheels to the neutral position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for steering a rear wheel of a vehicle.

[0002]

2. Description of the Related Art Conventionally, a rear wheel steering system has been developed which improves steering performance of a vehicle by steering not only the front wheels of the vehicle but also the rear wheels. For example, Japanese Patent Laid-Open No. 3-14
In Japanese Patent No. 3773, a control unit using a microprocessor calculates a steering angle amount of rear wheels, and a rear wheel steering angle mechanism is operated according to a calculation result. The rear wheel steering angle mechanism is controlled by an electric motor. When an abnormality occurs in the control unit, the clutch disposed between the electric motor and the rear wheel control mechanism is opened, and the rear wheel is returned to the neutral position by the return spring provided in the rear wheel steering angle mechanism.

[0003]

In a vehicle, the power source for the electric motor is derived from the battery. Since the capacity of the vehicle battery is limited, it is desirable that the electric motor that drives the rear wheels also be power-saving. However, if a return spring is provided for neutral return in the event of an abnormality, the rear wheels must be steered against the spring force of the return spring, resulting in a large loss of energy in the electric motor and a battery with a larger capacity than usual. Had to pile up. When the battery has a large capacity, the weight of the battery also increases, and as a result, the acceleration performance and the fuel consumption deteriorate. Further, if the rear wheels are steered against the spring force of the return spring, the controllability will deteriorate. To improve controllability, the electric motor had to be made larger.

However, simply removing the return spring from the prior art makes it impossible to return the rear wheel to the neutral position when an abnormality occurs in the control unit.

If the rear wheels are left to be steered in either the left or right direction, the steering performance of the front wheels deteriorates.

In view of the above, the first object of the present invention is to use a return spring and to make it possible to return the rear wheel to the neutral position even when the control unit is abnormal.

When an electric motor is used, it is necessary to move and fix the wheel at a desired position against the reaction force that the wheel receives from the road surface. In order to receive the force from the road surface only by the electric motor, a considerably large electric motor is required. Here, it is conceivable to provide a hypoid gear with zero reverse efficiency between the electric motor and the rack shaft that drives the wheels, but since the conventional return spring is provided on the rack shaft, even if the electric motor is free, The movement of the rack shaft is blocked by the hypoid gear, which makes it impossible to return to the neutral position. Therefore, when a failure occurs in the drive system, the rear wheels are fixed in the steered state.

Therefore, a second object of the present invention is to make it possible to return the rear wheel to the neutral position even if a hypoid gear having zero reverse efficiency is provided.

[0009]

According to the invention of claim 1, which is used for solving the first problem, a motor; a rear wheel steering mechanism controlled by the rotation of the motor; and the motor is independently rotated. A motor driver; a main control means capable of controlling the motor driver; a sub-control means capable of controlling the motor driver; connected to the main control means, the sub-control means and the motor driver, between the main control means and the motor driver or a sub Switching means for connecting either one of the control means and the motor driver; abnormality detection means for detecting abnormality of the main control means; selection means for switching the switching means from the main control means side to the sub control means side when the main control means has abnormality Equipped with; Here, the main control means adjusts the rear wheel steering angle according to the state of the vehicle. Further, the sub-control unit returns the rear wheel to the neutral position when the main control unit is abnormal.

Further, in the invention of claim 2 used to solve the first problem, a motor; a rear wheel steering mechanism controlled by the motor; a motor driver for rotating the motor; Connected switching means; a first microprocessor capable of calculating a steering angle amount of rear wheels according to a vehicle state and controlling a motor driver via the switching means; a second microprocessor performing the same calculation as that of the first microprocessor A microprocessor; a backup microprocessor capable of controlling the motor driver via the switching means; and a selection means for switching the switching means. Here, the first microprocessor compares the operation result of the second microprocessor with its own operation result, identifies that either the first microprocessor or the second microprocessor is abnormal, and either If it is abnormal, the first abnormal signal is output. Further, the second microprocessor compares the operation result of the first microprocessor with its own operation result, identifies that either the first microprocessor or the second microprocessor is abnormal, and either is abnormal. If
The second abnormal signal is output. Further, the selection means switches the switching means from the first microprocessor side to the backup microprocessor side when receiving either one of the first and second abnormality signals. Further, the backup microprocessor returns the rear wheel to the neutral position when receiving one of the first and second abnormal signals.

Further, in the invention of claim 3 used for solving the above-mentioned second problem, in the configuration of claim 1 or 2, the rear wheel steering mechanism is provided with a rear wheel according to a lateral movement amount. A rack shaft for steering, a pinion for laterally moving the rack by rotation, and a pinion fixed to the pinion,
And a hypoid gear of zero reverse efficiency rotated by the motor.

[0012]

According to the first aspect of the invention, when the main control means is normal, the main control means drives the motor driver to rotate the motor. Here, when the main control means becomes abnormal, the abnormality detection means detects the abnormality, and in response to this, the selection means connects the sub-control means and the motor driver. The sub control means returns the rear wheel to the neutral position. Therefore,
When the main control means is abnormal, the sub-control means returns the rear wheel to the neutral position.

According to the second aspect of the present invention, the first microprocessor and the second microprocessor calculate the steering angle amount of the rear wheels according to the vehicle state, and control the motor driver through the switching means. . Here, when one of the first microprocessor and the second microprocessor becomes abnormal, the first microprocessor and the second microprocessor
Since the calculation results of the microprocessor become different, the first abnormal signal is output from the first microprocessor or the second abnormal signal is output from the second microprocessor. At this time, the selection means switches the switching means from the first microprocessor side to the backup microprocessor side, and the backup microprocessor returns the rear wheel to the neutral position.

According to the third aspect of the present invention, since the rear wheel steering mechanism is provided with the hypoid gear of zero reverse efficiency, the motor shaft does not rotate even if a force is applied from the wheel side of the rear wheels. The rack shaft moves and the rear wheels can be steered only when the motor driver drives the motor.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the construction of a vehicle equipped with the rear wheel steering system of the present invention. The front wheels 13 and 14 are steered by the front wheel steering device 10 in accordance with the rotational scanning of the steering wheel 19. The steering amount of the front wheels is detected by a first front wheel steering angle sensor 17 that detects a movement amount of a rack of the front wheel steering device 10 and a second front wheel steering angle sensor 20 that is provided on a steering shaft to which a steering wheel 19 is attached. . The first front wheel steering angle sensor 17 uses a linear sensor such as a potentiometer, and the second front wheel steering angle sensor 20 uses a steering sensor such as a rotary encoder that emits a pulse during rotation.

The rear wheels 15 and 16 are steered by the rear wheel steering mechanism 11. The rear wheel steering mechanism 11 operates according to the rotation of the motor 12. A magnetic pole sensor 18 for detecting the rotation angle of the motor 12 is provided at the end of the motor 12. Further, a rear wheel steering angle sensor 21 for detecting the actual steering angle of the rear wheels 15 and 16 is provided on a rack shaft 25 as a rear wheel steering shaft. The rear wheel steering angle sensor 21 may be built in the rear wheel steering angle mechanism 11.

The vehicle also detects the speed of the vehicle. 2
The system includes a first vehicle speed sensor 22, a second vehicle speed sensor 23, and a yaw rate sensor 24 that measures the yaw rate of the vehicle.

The motor 12 is controlled by a signal from the electronic control unit 9. The electronic control unit 9 includes a first front wheel steering angle sensor 17, a second front wheel steering angle sensor 20, a magnetic pole sensor 18, a rear wheel steering angle sensor 21, a first vehicle speed sensor 22, a second vehicle speed sensor 23, and a yaw rate sensor 24. Receiving sensor output,
The amount of rotation of the motor 12 is determined and a control signal is sent to the motor 12 for control.

The rear wheel steering mechanism 11 is shown in FIG. Here, an example in which the rear wheel steering angle sensor 21 is built in the rear wheel steering mechanism 11 is shown. The rear wheel steering mechanism 11 includes a magnetic pole sensor 18,
The motor housing 40 of the motor 12 and the rear wheel steering angle sensor 21 are integrally provided on a cover 36 fixed to the housing 38. FIG. 3 is a partial cross-sectional view of the rear wheel steering mechanism 11 shown in FIG. The rack shaft 25 is provided at a right angle to the traveling direction of the vehicle. Rack shaft 25
Both ends of are connected to knuckle arms of the rear wheels via ball joints 53. Both ends of the rack shaft 25 are protected by boots 28. A tube 39 is fitted to the right end of the housing 38 in the drawing. Tube 3
By exchanging 9, the length of the rack shaft 25 can be changed without changing the housing 38. A rack 26 is engraved on the rack shaft 25, and the rack 26 meshes with a pinion 27 extending in the front-rear direction of the vehicle. The rack guide cover 32 is fixed to the housing 38, and the rack guide 3
By biasing 1 toward the rack 26, the rack 26
Is pressed to the pinion 27 side. The pinion 27 is fixed to the gear 29 by shrink fit (press fit) as shown in FIG. 4, and the pin 37 prevents relative rotation.

The rear wheel steering angle sensor 21 is parallel to the surface of the gear 29.
Is provided. The rear wheel steering angle sensor 21 has a built-in potentiometer and detects the rotation angle of the shaft 54. The shaft 54 has
A pin 34 is provided via the lever 33. Pin 3
4 is fitted in a hole 35 provided in the gear 29. As a result, when the gear 29 rotates, the shaft 54 also rotates with it. Since the rotation amount of the gear 29 is proportional to the lateral movement amount of the rack shaft 25, the steering angle amount of the rear wheels can be detected by the rear wheel steering angle sensor 21.

As shown in FIG. 3, the gear 29 is the motor 12
Engages with the pinion 30 provided at the tip of the motor shaft 41 of the. The pinion 30 and the gear 29 form a hypoid gear. This hypoid gear is the motor shaft 4 of the motor 12.
1 rotation is transmitted as rotation of the gear 29, but the rack shaft 2
When trying to rotate the gear 29 from the 5 side, the motor 1
The second motor shaft 41 is set so that the reverse efficiency becomes zero so as not to rotate.

Further, the pinion 30 and the gear 29 form an HRH (high ratio hypoid) gear so as to have a large reduction ratio. The gear ratio is determined by the number of poles of the motor 12, the resolution of the steering angle, etc., and therefore varies depending on the vehicle, but is set to 67: 1 in this embodiment.

A cross section of the motor 12 is shown in FIG. The motor shaft 41 is rotatably supported in the motor housing 40. A two-pole magnet 42 is fixed around the motor shaft 41. A core 43 is fixed to the motor housing 40 so as to face the magnet 42, and a motor winding 44 is wound around the core 43. FIG. 6 shows the motor 12 of FIG.
The AA cross section of is shown. Twelve protrusions 43a extending inward are formed on the core 43, and the motor winding 44
Is wound around this protrusion 43a. FIG. 7 shows how to wind the motor winding 44. FIG. 7 is a view of the motor winding 44 seen from the magnetic pole sensor 18 side. The motor winding 44 is wound in six phases, but has two systems in which half of the three phases is one system. Winding 44a, 44b, 44c is the first system, winding 44
The second system is d, 44e, and 44f. Winding 44
One ends of a, 44b, 44c, 44d, 44e and 44f are output from terminals U1, V1, W1, U2, V2 and W2, respectively. The other ends of the windings 44a, 44b, 44c are electrically connected. Also, the windings 44d, 44
The other ends of e and 44f are also electrically connected. Thus, the motor 12 is a three-phase two-pole two-system brushless motor. Therefore, even if one system does not move due to a failure, the motor can be rotated by the other system.
Also, if the two systems are operated at the same time, the power will not decrease. The motor winding 44 is connected to a wire harness 46 via a terminal 45 for each system.

In FIG. 5, one end of the motor housing 40 is an open end, and the magnetic pole sensor 18 is attached thereto. The holder 47 of the substrate 49 is fixed to the open end of the motor housing 40. Three Hall ICs 50 are provided on the substrate 49. A rotor 52 is fixed to the end of the motor shaft 41 of the motor 12. A magnet 51 is provided on the rotor 52. Holder 47
Is covered by a cover 48. As shown in FIG. 8, the magnet 51 is formed in a two-pole disc shape. As shown in FIG. 9, three Hall ICs 50 are arranged on the substrate 49, each being shifted by 60 degrees. 3 holes I
The output of C50 is used as magnetic pole signals HA, HB, HC in the electronic control unit 9 described later.

When the motor shaft 41 rotates, as shown in the rotating state of the magnet 51 in FIG.
The magnet 51 rotates with respect to C), and the three magnetic pole signals HA, HB, and HC that are the three outputs of the magnetic pole sensor 18 change between a high level (H) and a low level (L) as illustrated. FIG. 10 shows a state in which the motor is rotating clockwise (CW). When the motor rotates counterclockwise (CCW), the magnetic pole signals HA, HB, HC of the magnetic pole sensor 18 are switched in the direction from the right to the left in the figure. This magnetic pole signal HA,
If the winding current of the motor winding 44 is switched in synchronism with the switching between HB and HC, the motor will rotate. The current direction when the motor rotates will be described later.

Next, the details of the electronic control unit 9 will be described with reference to FIG. The electronic control unit 9 is a vehicle battery 5
9 is connected. The battery 59 is connected to the power supply terminal PIGA via the fuse and the relay 77 and to the power supply terminal PIGB via the fuse and the relay 78. Relays 77 and 78 are opened and closed by relay drive circuits 79 and 80, respectively. Further, the battery 59 is a fuse and an ignition switch IGSW.
Is connected to the power supply terminals IGA and IGB via. The power supply terminals IGA and IGB are connected to the first constant voltage regulator 55 and the second constant voltage regulator 56, respectively. The first constant voltage regulator 55 outputs a constant voltage Vcc1. The second constant voltage regulator 56 has a constant voltage Vcc.
2 is output.

The electronic control unit 9 is a first control unit, which is the first control unit.
It has three microprocessors, a microprocessor 1, a second microprocessor 2 and a backup microprocessor 3 which is a sub-control means. The first microprocessor 1 and the second microprocessor 2 have a constant voltage Vcc1.
Operated by. Backup microprocessor 3
Operates with a constant voltage Vcc2. The above-described first front wheel steering angle sensor 17, second front wheel steering angle sensor 20, first vehicle speed sensor 22, second vehicle speed sensor 23, yaw rate sensor 24,
The output of the magnetic pole sensor 18 is input to the first microprocessor 1 and the second microprocessor 2 via the interface 57, respectively. In addition, the rear wheel steering angle sensor 21
Is output to the first microprocessor 1, the second microprocessor 2 and the backup microprocessor 3 via the interface 58. Here, the output of the first front wheel steering angle sensor 17 is θf1, the output of the second front wheel steering angle sensor 20 is θf2, the output of the first vehicle speed sensor 22 is V1, the output of the second vehicle speed sensor 23 is V2, and the yaw rate sensor 24. Of the magnetic pole sensor 18 is HA, HB, HC, and the output of the rear wheel steering angle sensor 21 is θ.
r.

As described above, the electronic control unit 9 controls the three-phase / two-system motor 12. Here, the two systems of motors are described as M1 and M2, respectively. The terminals U1, V1, W1 of each phase of the motor M1 are connected to the first motor driver 5 of the electronic control unit 9. The terminals U2, V2, W2 of each phase of the motor M2 are connected to the second motor driver 6 of the electronic control unit 9.

Details of the first motor driver 5 will be described with reference to FIG. The first motor driver 5 uses the phase switching signals LA11, LB11, LC11, LA21,
It is controlled by a phase switching signal group L1 including LB21 and LC21 and a pulse width modulation signal PWM1. The phase switching signals LA11, LB11, LC11 for controlling the high side are abnormal current limiting circuits 88.
Is input to the gate drive circuit G11 via. The abnormal current limiting circuit 88 normally outputs the input signal as it is from the output side. The gate drive circuit G11 drives transistors TA11, TB11, TC11, which are power MOSFETs, on and off. The gate drive circuit G11 also boosts the voltage, and applies the boosted voltage to the gates of the transistors TA11, TB11, and TC11. At the same time, the gate drive circuit G11 outputs the boosted voltage as the boosted voltage value RV1.
Transistors TA11, TB11, TC11 are arranged so that a high voltage obtained from the power supply terminal PIGA via the pattern fuse PH, the choke coil TC and the resistor Rs can be supplied to each of the three-phase terminals U1, V1, W1 of the motor M1. Has been done. Incidentally, the transistors TA11, TB
Zener diodes are inserted between the gates and sources of the 11, TC11, TA21, TB21, and TC21 to protect the power MOSFET. this is,
If the power supply voltage exceeds 20V for some reason, the power M
This is to prevent the gate-source voltage of the OSFET from exceeding 20 V and destroying the power MOSFET.

In this case, the circuits 77 are protected by turning off the relays 77 and 78 and turning off the drive signals of the transistors. On the other hand, the phase switching signals LA21, LB21, LC21 for controlling the low side are supplied to the pulse width modulation signal synthesis circuit 89 and the abnormal current limiting circuit 8.
It is connected to the gate drive circuit G21 through 8. The pulse width modulation signal synthesis circuit 89 uses the phase switching signals LA21 and L21.
B21 and LC21 are each a pulse width modulation signal PWM1
And synthesize. The gate drive circuit G21 turns on the transistors TA21, TB21 and TC21 which are MOSFETs.
Drive off. These transistors TA21, TB2
1, TC21 are three-phase terminals U1, V of the motor M1.
1, W1 and the ground of the battery 59 are arranged to be connectable. Each transistor TA11, TB11, T
Protective diodes D3 to 8 are connected to C11, TA21, TB21, and TC21, respectively. The voltage applied to the transistors TA11, TB11, TC11 is output as the voltage PIGM1. This voltage PIGM1
And the boosted voltage value RV1 of the gate drive circuit G11 decreases to about 2V, the transistors TA11, TB11, TC11, TA21, TB21, which are MOSFETs,
The on-resistance of the TC 21 may increase, which may cause abnormal heat generation. Therefore, the voltage PIGM1 and the gate drive circuit G
When the difference from the boosted voltage value RV1 of 11 becomes equal to or less than a predetermined value, all the transistors TA11, TB11, TC11, TA2
It is preferable to turn off 1, TB21 and TC21. Incidentally, the transistor TA21 connected to the ground,
Since a large current flows through the sources of TB21 and TC21,
It is preferable to wire the ground in a system different from the ground of the light electric circuit unit such as the microprocessor.

A current detection circuit 86 is provided at both ends of the resistor Rs and detects the value of the current flowing through the resistor Rs.
Further, in the current detection circuit 86, the value of the current flowing through the resistor Rs is 1
When it is 8 A or more, it is determined to be an overcurrent, and the overcurrent signal is output from the output signal MOC1. Further, the current detection circuit 86 determines that the current is an abnormal current when the current value flowing through the resistor Rs is 25 A or more, and outputs an abnormal current signal from the output signal MS1. When an overcurrent occurs, an overcurrent signal is given to the pulse width modulation signal synthesis circuit 89 to limit the low side. When an abnormal current occurs, the abnormal current limiting circuit 88
An abnormal current signal is applied to and the high side and low side are limited. In this case, all transistors TA1
1, TB11, TC11, TA21, TB21, TC2
1 may be turned off for a certain period of time after the abnormal current is detected. This fixed time is FE for the maximum expected current
It may be set to be within the safe operation area of T.

The current value detected by the current detection circuit 86 is given to the peak hold circuit 101. The peak hold circuit 101 outputs the peak value of the current value to the peak signal MI1.
Output as. The peak hold circuit 101 is reset at the timing when the reset signal DR1 switches.

Next, the rotating operation of the motor M1 will be described with reference to FIG. 10 again. The pattern of the phase switching signal is
The motor M1 rotates when set as shown in Table 1 according to the states of the magnetic pole signals HA, HB, and HC. Clockwise rotation (C
W) is set to the right and the counterclockwise rotation (CCW) is set to the left. It is assumed that the magnetic pole signal is (HA, HB, HC) = (H, L, H) as in the case of clockwise rotation 1 in Table 1. At this time, the phase switching signal (LA11, LB
11, LC11, LA21, LB21, LC21) =
(H, L, L, L, H, L) is output. This state shows the state in the range of A in FIG. As shown in the rotating state of the magnet 51 of the magnetic pole sensor 18, the inner magnetic pole signals HA and HC of the three Hall ICs are at a high level. The direction of the winding current changes from U to V. At this time, the motor rotates and the magnet 51 rotates clockwise in the drawing. When the magnet 51 rotates about 15 degrees, the magnetic pole signal HA switches from the high level to the low level. In accordance with this, the phase switching signal (LA1
1, LB11, LC11, LA21, LB21, LC2
1) = (H, L, L, L, H, L), the motor will rotate continuously. As described above, in order to apply the clockwise rotation (CW) or the counterclockwise rotation (CCW) to the motor, the pattern of the phase switching signal may be switched according to the order of Table 1.

[0035]

[Table 1]

The second motor driver 6 has almost the same structure. However, the phase switching signals LA11, LB11, L
Phase switching signals LA12, LB12, instead of the phase switching signal group L1 composed of C11, LA21, LB21, LC21.
A phase switching signal group L2 including LC12, LA22, LB22, and LC22 is input, and a pulse width modulation signal PWM2 is input instead of the pulse width modulation signal PWM1 and output to each of three-phase terminals U2, V2, W2 of the motor M2. It is different in that it is done.

The failure of the motors M1 and M2 can be detected by the peak hold value of the peak hold circuit 101 in addition to the above-mentioned abnormal current value. Motor M1,
In M2, the current flows in either the U-phase-V phase, the V-phase-W phase, or the W-phase-U phase. Therefore, if the current flowing to the motor is peak-held at each phase switching, the peak value is always the same. Should be a level. Here, for example, U
When the phases are broken, the current does not flow between the U-phase and the V-phase or between the W-phase and the U-phase, and the peak value of the current increases only when the current flows between the V-phase and the W-phase. If the U phase is short-circuited, the U phase-
The current doubles between V-phase or between W-phase and U-phase, and V-phase-W
Only when flowing between phases does the peak value of the current drop. Therefore, if the peak value for each phase switching is not at the same level for three consecutive times, it can be determined that one of the phases is abnormal. Also, the motor current can be estimated from the motor rotation speed and PWM. If the peak hold value of the current deviates from this estimated value, it can be determined that the motor is abnormal.

In FIG. 11, the first motor driver 5
Obtains power from power supply terminals PIGA and IGA. First
The first relay 7 is connected to the input of the motor driver 5 via the third relay 75. The first relay 7 is the first
Phase switching signal group L1 which is a signal output from the microprocessor 1 (L1 is phase switching signal LA11, LB11, L
C11, LA21, LB21, LC21) and the pulse width modulation signal PWM1, and the phase switching signal group L3 (L3 is the phase switching signals LA11, LB11, which are the signals output from the backup microprocessor 3).
One of the signal group consisting of LC11, LA21, LB21, LC21) and the pulse width modulation signal PWM3 is applied to the third relay 75. In addition, the third relay 75,
Connection / disconnection between the first relay 7 and the first motor driver 5 is performed. The first relay 7 is switched by the signal S3 from the selector 4. The third relay 75 is controlled by the signal S5 from the brake signal generating circuit 67. The brake signal generation circuit 67 cuts off the relay 75 for a predetermined time when the signal S3 from the selector 4 is switched to the low level. When the relay 75 is cut off, the phase switching signal groups L1 and L3 and the pulse width modulation signals PWM1 and PWM3 are not given to the first motor driver 5, and the motor M1 is braked.

Similarly, terminals U2 and V of each phase of the motor M2
2 and W2 are connected to the second motor driver 6 of the electronic control unit 9. The second motor driver 6 has a power supply terminal P
Power is obtained from the IGB and the IGB. The second relay 8 is connected to the input of the second motor driver 6 via the fourth relay 76.
Are connected. The second relay 8 includes a phase switching signal group L1 and a pulse width modulation signal PWM1 which are signals output from the first microprocessor 1, and a phase switching signal group L3 and a pulse which are signals output from the backup microprocessor 3. Either one of the width modulation signal PWM3 is given to the fourth relay 76. Also, the fourth relay 76
Is the connection between the second relay 8 and the second motor driver 6.
Shut off. The second relay 8 receives the signal S4 from the selector 4.
Can be switched by. The fourth relay 76 is controlled by the signal S6 of the brake signal generation circuit 68. The brake signal generation circuit 68 cuts off the relay 76 for a predetermined time when the signal S4 from the selector 4 is switched to the low level. When the relay 76 is cut off, the phase switching signal groups L1 and L3 and the pulse width modulation signals PWM1 and PWM3 are not given to the second motor driver 6, and the motor M2 is braked.

The selector 4 receives the signal S1 from the first microprocessor 1, receives the signal S2 from the second microprocessor 2, and outputs the signals S3 and S4 to the first signal respectively.
Output to the relay 7 and the second relay 8. Signals S3 and S
4 is also sent to the backup microprocessor 3.

The second microprocessor 2 intercepts the phase switching signal group L1 and the pulse width modulation signal PWM1 output from the first microprocessor 1. The second microprocessor 2 is transmitting and receiving data with the first microprocessor 1.

The structure of the selector 4 is shown in FIG. The selector 4 is provided with a comparator COMP1 that monitors the power supply voltage. The comparator COMP1 has a power supply terminal I
The power supply voltage is obtained from GA and IGB via diodes D1 and D2. This power supply voltage is divided by a resistor to generate a reference voltage ref. The reference voltage ref is set to a voltage slightly higher than the constant voltage Vcc1 described above. In the case of this embodiment, Vcc1 outputs about 5V. Therefore, the reference voltage ref is set to about 7V. The comparator COMP1 compares the reference voltage ref with the voltage value of the constant voltage Vcc1. When the voltage value of the constant voltage Vcc1 is normal, the comparator COMP1 outputs a low level voltage. When the voltage value of the constant voltage Vcc1 becomes higher than the reference voltage ref, the comparator COMP1 outputs a high level voltage. Comparator COMP1
Is inverted and input to the AND circuits AND1 and AND2. Output S1 from the first microprocessor 1 and output S from the second microprocessor 2
Similarly, 2 is also inverted and input to the AND circuits AND1 and AND2. The output S1 of the first microprocessor 1 has a high level when an abnormality determination is made in the first microprocessor 1, and has a low level otherwise. Further, the output S2 of the second microprocessor 2 becomes high level when an abnormality determination is made in the second microprocessor 2, and becomes low level otherwise. Therefore, the output S3 of the AND circuit AND1 and the output S4 of the AND circuit AND2 determine that the value of the constant voltage Vcc1 abnormally rises, the first microprocessor 1 determines the abnormality, or the second microprocessor 2 determines the abnormality. Sometimes it goes low. The first relay 7 is switched to the backup microprocessor 3 side when the signal S3 is at a low level. Further, the second relay 8 is switched to the backup microprocessor 3 side when the signal S4 is at a low level. When the constant voltage Vcc1, the first microprocessor 1, and the second microprocessor 2 are normal, the signals S3 and S4 are at high level. The first relay 7 is switched to the first microprocessor 1 side when the signal S3 is at high level. The second relay 8 is switched to the first microprocessor 1 side when the signal S4 is at high level.
As a result, when the system including the constant voltage Vcc1, the first microprocessor 1, the second microprocessor 2 and the like is normal, the first motor driver 5 and the second motor driver 6 cause the phase switching signal group L from the first microprocessor 1 to operate.
1 and the pulse width modulation signal PWM1 according to the motor M
Rotate 1, M2. When an abnormality occurs in the system, the first motor driver 5 and the second motor driver 6 rotate the motors M1 and M2 according to the phase switching signal group L3 and the pulse width modulation signal PWM3 from the backup microprocessor 3. . Therefore, even when the system is abnormal, the backup microprocessor 3 can control the motor. Since the constant voltage Vcc2 is used for the power supply of the backup microprocessor 3, the motor can be controlled even when the constant voltage Vcc1 is abnormal. When the constant voltage Vcc2 is abnormal, the first microprocessor 1 can control the motor. The signals S3 and S4
Since the relays 75 and 76 are turned off for a predetermined time by the motor brake generation circuits 67 and 68 for a predetermined time after switching, the motors M1 and M2 are braked, so that the motors M1 and M2 are stopped. After that, the backup microprocessor 3 performs neutral return of the motor.

Next, the configuration of the first microprocessor 1 and the second microprocessor 2 is shown in FIG. The first microprocessor 1 and the second microprocessor 2 have almost the same configuration, and differ in that the output signal of the first microprocessor 1 is sent to the first relay 7 and the second relay 8. The configuration of the first microprocessor 1 will be described below. The control of the first microprocessor 1 is represented by a block diagram. The target rudder angle calculation unit 60, the motor servo control unit 61, the phase switching control unit 62, the magnetic pole sensor abnormality determination unit 63, the open control unit 64, and the second microprocessor monitoring. It is composed of a section 65 and a switch SW1. Incidentally, when the control of the second microprocessor 2 is similarly represented by a block diagram,
The target steering angle calculation unit 66, the motor servo control unit 70, the phase switching control unit 71, the magnetic pole sensor abnormality determination unit 72, the open control unit 73, the first microprocessor monitoring unit 74, and the switch SW2.

The target steering angle calculation unit 60 calculates the target steering angle value AGLA from the yaw rate value γ, the vehicle speed V and the steering angle θs.
Ask for. Although not shown, the vehicle speed V is obtained from the output values V1 and V2 of the two vehicle speed sensors 22 and 23. At this time, the average of the two vehicle speed values may be the vehicle speed V, or the maximum value of the two vehicle speed values may be the vehicle speed V. By detecting the vehicle speed with two systems, it is possible to detect an abnormality of the vehicle speed sensor. Although not shown, the front wheel steering angle θs
Are output values θf1, θ of the two front wheel steering angle sensors 17, 20
Calculate from f2. Normally, a potentiometer is used for the first front wheel steering angle sensor 17, but the potentiometer has a rough accuracy. Further, if a rotary encoder is used for the second front wheel steering angle sensor 20, the steering angle amount can be accurately detected, but the initial steering angle amount cannot be detected. Therefore, the neutral point of the output of the second steering angle sensor 20 is calculated by the first front wheel steering angle sensor 17, and after the neutral point is calculated, the output of the second front wheel steering angle sensor 20 is set as the steering angle θs.

A control block diagram of the target rudder angle calculation unit 60 is shown in FIG. The steering gain setting unit 82 and the yaw rate gain setting unit 83 respectively adjust the steering gain K1 (V) and the yaw rate gain K2 according to the value of the vehicle speed V.
(V) is set. The accumulator 84 has a steering gain K.
1 (V) and the steering angle θs are integrated to obtain the steering control amount θ2. The accumulator 85 has a yaw rate gain K.
2 (V) and the yaw rate γ are integrated to obtain the yaw rate control amount θ3. On the other hand, the anti-phase amount setting unit 81 obtains the anti-phase control amount θ1 from the steering angle θs. The adder 87 adds the antiphase control amount θ1, the steering control amount θ2, and the yaw rate control amount θ3 to obtain the target steering angle AGLA.

Here, the anti-phase amount setting section 81 sets the anti-phase control amount θ1 to zero when the steering angle θs is about 200 degrees or less, and sets a predetermined gain when the steering angle θs is about 200 degrees or more. It is set to hang. As a result, when the driver turns the steering wheel 19 largely, the target steering angle AGLA is in the opposite phase, and the vehicle can make a small turn. Since the steering wheel 19 is not rotated more than 200 degrees during high speed traveling, the rear wheels are not in reverse phase during high speed traveling.

The steering gain setting unit 82 sets the steering gain K1 (V) to zero when the vehicle speed is, for example, 30 km / h or less, and sets it to a negative value when the vehicle speed is about 30 to 40 km / h, and sets 40 km / h.
With the above, a positive value is obtained. In addition, the yaw rate gain setting unit 8
3 is the yaw rate gain K2 (V), and the vehicle speed is 30
It is set to zero at Km / h or less, and set to a positive value at about 30 to 40 Km / h or more. Note that the specific numerical values differ depending on the vehicle. As a result, when the vehicle is traveling at a low speed of about 30 km / h, the steering angle control amount of the rear wheels is limited to the antiphase control amount θ1 described above, and when the vehicle speed becomes high, the in-phase control is performed according to the steering angle and the yaw rate. Here, the steering gain K1 (V) is 30 to 40 km / h.
The reason why the value is set to a negative value is to perform the phase reversal control in which the reverse phase control is performed for a moment during steering during traveling and then the phase is changed to the same phase (returns to the same phase when the yaw rate starts to appear). Incidentally, the yaw rate control amount θ3 is set in order to increase the steering feeling.
You may make it apply a limiter more than a predetermined amount.

FIG. 16 shows a control block diagram of the motor servo control section 61. The differentiating part 90 differentiates the target steering angle value AGLA to obtain a differential value SAGLA. Differential gain setting unit 91
Is the differential gain YTD from the differential value SAGLA of the target steering angle value.
Ask for IFGAIN. Here, the differential gain YTDIFGAIN is obtained from the absolute value of the differential value SAGLA. When the absolute value of the differential value SAGLA is 0.12 deg or less, the differential gain is 0, and the absolute value of the differential value SAGLA is 0.48.
The differential gain is set to 4 when it is deg or more, and the differential gain becomes a value of 0 to 4 when the absolute value of the differential value SAGLA is 0.12 to 0.48 deg. The rotation angle θm of the motor M1 is obtained from the output of the magnetic pole sensor 18. Although not shown, the motor rotation angle θm is the output value HA, HB, HC of the magnetic pole sensor 18 and the output value θr of the rear wheel steering angle sensor 21.
Ask from. Normally, a potentiometer is used for the rear wheel steering angle sensor 21, but the potentiometer has a rough accuracy. Further, although the magnetic pole sensor 18 can accurately detect the steering angle amount,
The initial steering angle amount cannot be detected. Therefore, the neutral point of the magnetic pole sensor 18 is obtained by the rear wheel steering angle sensor 21, and after the neutral point is obtained, the motor rotation angle θm is obtained from the output change of the magnetic pole sensor 18. Rotation angle θm is buffer 100
Is given to the subtraction unit 92 as the actual steering angle value RAGL. The subtraction unit 92 calculates the actual steering angle value RA from the target steering angle value AGLA.
GL is subtracted to obtain the steering angle deviation ΔAGL. This steering angle deviation ΔAGL is processed via the deviation steering angle dead zone imparting section 93. When the absolute value of the steering angle deviation ΔAGL is less than or equal to the predetermined value E2PMAX, the deviation steering angle dead zone imparting unit 93 determines the steering angle deviation value E.
TH2 is processed as 0, and the steering angle deviation ΔAG
When the value of L is small, the control is stopped. The obtained steering angle deviation value ETH2 is proportional to the proportional portion 96 and the differential portion 9
Sent to 4. The proportional portion 96 integrates the steering angle deviation value ETH2 by a predetermined proportional gain to obtain a proportional term PAGELA. Further, the differentiating unit 94 differentiates the steering angle deviation value ETH2 to obtain the steering angle deviation differential value SETH2. Steering angle deviation differential value SETH2
And the above-mentioned differential gain YTDIFGAIN
And the differential term DAGLA is obtained. The proportional term PAGLA and the differential term DAGLA are added by the adder 97 to obtain the steering angle value HPID. The steering angle value HPID is limited by the deviation steering angle limiter 98. The deviation steering angle limiter 98 gives the control amount ANG in proportion to the steering angle value HPID, and also gives the control amount ANG so that the control amount does not become 1.5 deg or more or −1.5 deg or less. The control amount ANG is converted into a pulse width modulation signal by the pulse width modulation conversion unit 99 and sent to the first motor driver 5. The first motor driver 5 rotates the motor M1 according to the pulse width modulation signal. In this way, the motor M1 is servo-controlled. Further, the steering angle deviation is PD-controlled. Among these, the differential gain of the differential term is changed according to the differential value of the target steering angle value. The differential gain becomes 0 when the differential value of the target steering angle value is small, and the control is performed only by the proportional term. An integral term may be added to the PD control. Further, since the rotation angle of the motor M1 changes depending on the fluctuation of the power supply voltage, the battery voltage may be measured and the control amount AGL may be corrected according to the battery voltage.

As shown in FIG. 17, the interrupt terminal and the normal input terminal of the first microprocessor 1 are used for the input terminals of the magnetic pole sensor signals HA, HB, HC of the first microprocessor 1. The magnetic pole sensor signals HA and HB are connected to the input terminals of the exclusive OR circuit EXOR1. The output terminal of the magnetic pole sensor signal HC and the exclusive OR circuit EXOR1 is the exclusive OR circuit E.
It is connected to the input terminal of XOR2. If any one of the magnetic pole sensor signals HA, HB, HC changes,
The output of the exclusive OR circuit EXOR2 changes.

When there is a change in any one of the magnetic pole sensor signals HA, HB, HC, the first microprocessor 1
Executes a magnetic pole sensor signal edge interrupt routine as shown in FIG. This magnetic pole sensor signal edge interrupt routine recognizes the magnetic pole sensor signal and also functions as the magnetic pole sensor abnormality determination unit 63 of FIG. Here, each time there is an interrupt, the state of the magnetic pole sensor signal is read and stored as the current value, and the current value stored so far is updated as the previous value. In FIG. 18, in step 200, the magnetic pole sensor signal stored so far is updated as the previous value. Next, at step 201, the states of the input terminals of the magnetic pole sensor signals HA, HB, HC are read and stored as current values. Next, at step 202, the previous predicted value is read from the map shown in Table 2. As will be described later, the magnetic pole sensor 18 is configured so that any one of the magnetic pole sensor signals HA, HB, and HC sequentially changes. Therefore, the polarity of any one of HA, HB, and HC should change from the previous value and the current value. In the previous predicted value of the map of Table 2, all possible states for the current value are stored. Specifically, the current value is (HA, HB, HC) =
When (L, L, H), the previous predicted value is (H, L,
H) or (L, H, H). Step 2 of FIG.
In 03, this previous predicted value is compared with the actual previous value.
If the magnetic pole sensor 18 is functioning normally, the previous predicted value and the previous value should match. If the previous predicted value and the previous value match, the abnormality flag Fabn is set to 0 in step 204. If the previous predicted value and the previous value do not match, the abnormality flag Fabn is set to 1 in step 205.

After that, the magnetic pole sensor signal edge interrupt routine is terminated. As a result, in the subsequent processing, if the abnormality flag Fabn is 1, it can be known that the magnetic pole sensor 18 has an abnormality.

[0052]

[Table 2]

FIG. 19 is a flow chart showing the operation of the phase switching control unit 62 in FIG. In step 210, if the above-mentioned abnormality flag Fabn is 1, the following processing is skipped. That is, the phase switching control routine is not executed when the magnetic pole sensor 18 is abnormal. Step 21
At 1, it is determined whether or not there is an edge interrupt of the magnetic pole sensor signal. If there is an interrupt, step 2
At 12 to 214, the value CW is set to the direction flag DI if the clockwise rotation is to be performed, and the value CCW is set to the direction flag DI if the counterclockwise rotation is to be performed. Next, in step 215, the phase switching signal pattern is set based on the map in Table 3 below.

The phase switching signal is a 6-bit signal, and each bit is defined as shown in Table 4 below. Each bit can have a high level “H” and a low level “L”. In step 215, the next phase switching pattern is set from the state of the phase switching pattern and the direction flag DI that have been output so far. For example, if the current value is (LA11, LB11, LC1
1, LA21, LB21, LC21) = (H, L, L,
L, H, L) and DI = CW (clockwise rotation)
If so, (H, L, L, L, L, H) is set as the next value. The set phase switching pattern is output as a phase switching signal group L1 in the first microprocessor 1. The second microprocessor 2 outputs the phase switching signal group L2.

[0055]

[Table 3]

[0056]

[Table 4]

FIG. 20 is a flow chart showing the operation of the open control unit 64 shown in FIG. Step 220
Then, if the above-mentioned abnormality flag Fabn is 0, the following processing is skipped. That is, the open control routine is not executed when the magnetic pole sensor 18 is normal. Therefore, when the magnetic pole sensor 18 is normal, the above-described phase switching control routine is executed, and when the magnetic pole sensor 18 is abnormal, this open control routine is executed. In this open control routine, the open control in-execution flag Fop1 and the timer T are used. When the timer T is set to the predetermined time, the timer T is gradually decremented after that, and becomes 0 after the predetermined time. Open control execution flag Fop1
Is initially set to 0. In step 221, the state of the open control in-execution flag Fop1 is judged, and if the open control in-execution flag Fop1 is 0,
Next, at step 222, the timer T is set to a predetermined time (for example, 1 second). Then, in step 224, the motor brake pattern is set as the phase switching pattern until the timer T becomes 0 or less. The motor brake pattern is (LA11, LB11, LC11, LA
21, LB21, LC21) = (L, L, L, H, H,
H), (LA12, LB12, LC12, LA22, L
B22, LC22) = (L, L, L, H, H, H) is set. When the predetermined time has elapsed, the open control execution flag Fop1 is set to 1 in step 225. Next, since the timer T is 0 or less in this state, the next phase switching pattern is set from the map shown in Table 5 in step 227. Next, at step 228, the timer T is set again. In step 226, step 227 is executed only when the timer T is 0 or less, so step 227 is executed every predetermined time set in the timer T. In step 227, the next value is set according to the current phase switching pattern and the result of comparison between the rear wheel steering angle value θr output from the rear wheel steering angle sensor 21 and the predetermined value A1. A1 is set to a value close to zero (for example, 0.5 degrees). For example, the current phase switching pattern is (LA1
1, LB11, LC11, LA21, LB21, LC2
1) = (H, L, L, L, H, L) and when the rear wheel steering angle value θr is −1 degree, the next phase switching pattern is (H, L, L, L). , L, H). The map of Table 5 is set so that when the rear wheel steering angle value is negative, it rotates to the right, and when the rear wheel steering angle value is positive, it rotates to the left. In any case, the absolute value of the rear wheel steering angle acts so as to approach zero. When the absolute value of the rear wheel steering angle becomes a predetermined value A1 or less,
The phase switching pattern is (L, L, L, L, L, L).
In the case of this pattern, the motor 12 is stopped. Therefore,
In the open control routine, the phase switching pattern is controlled so that the rear wheel steering angle becomes zero and the neutral return is performed.

[0058]

[Table 5]

FIG. 21 is a flow chart showing the operation of the second microprocessor monitoring section 65 of FIG.
The first microprocessor 1 calculates its own pulse width modulation signal (PWM1), phase switching signal (phase switching signal group L
1), has a rotation direction (DI1). Further, the pulse width modulation signal (PWM2), the phase switching signal (phase switching signal group L2), and the rotation direction (DI2) calculated by the second microprocessor 2 are obtained from the second microprocessor 2 through communication. By comparing these with each other, an abnormality of the first microprocessor 1 or the second microprocessor 2 is detected. First, in step 230, the absolute value of the difference between the pulse width modulated signals is calculated, and it is determined whether or not it is smaller than the predetermined value A2. The predetermined value A2 is the first microprocessor 1, the second
It is determined in advance from the possible calculation error width in the microprocessor 2. In step 231, it is determined whether the phase switching signals match. In step 232, it is determined whether the rotation directions match. As a result of the determination, when the difference in the pulse width modulation signals between the first microprocessor 1 and the second microprocessor 2 is small, the phase switching signals match, and the rotation directions match, It is determined that both the first microprocessor 1 and the second microprocessor 2 are normal, and the signal S1 is set to low level. If there is any mismatch, the signal S1 is set to high level. When the signal S1 goes high, the selector 4 described above drives the relay to switch the first relay 7 and the second relay 8 from the first microprocessor 1 side to the backup microprocessor 3 side.

The first microprocessor monitoring section 74 of the second microprocessor 2 also performs substantially the same operation as the second microprocessor monitoring section 65 of the first microprocessor 1.

FIG. 22 shows the first microprocessor monitoring section 7
4 is a flowchart showing the operation of FIG. Steps 240 to 242 for making the determination are steps 230 to 2 of the second microprocessor monitoring unit 65 of the first microprocessor 1.
It is the same as 32. As a result of the determination, when the difference in the pulse width modulation signals between the first microprocessor 1 and the second microprocessor 2 is small, the phase switching signals match, and the rotation directions match, It is determined that both the first microprocessor 1 and the second microprocessor 2 are normal, and the signal S2 is set to low level. If there is a mismatch in any of them, the signal S2 is set to high level. When the signal S2 becomes high level, the selector 4 described above drives the relay to switch the first relay 7 and the second relay 8 from the first microprocessor 1 side to the backup microprocessor 3 side.

FIG. 23 is a flow chart showing the operation of the backup microprocessor 3. First, in step 250, the process waits until the signal S3 or S4 becomes high level. When the signal S3 or S4 becomes high level, next, in step 251, the process waits until the timer T becomes 0 or less. The timer T is a timer that counts down every time, and is initially set to a predetermined value. When the timer T becomes 0 or less, in step 252, the next phase switching pattern is set from the map shown in Table 5 above. Next, in step 253, the timer T is set to a predetermined time (for example, 1 second). Step 251
Since step 252 is executed only when the timer T is 0 or less, step 252 is thereafter executed every predetermined time set in the timer T. In step 252, the next value is set according to the current phase switching pattern and the result of comparison between the rear wheel steering angle value θr output from the rear wheel steering angle sensor 21 and the predetermined value A1. Here, the pattern of Table 5 used in the above-mentioned open control unit 64 is used as it is. Therefore, also in the control of the backup processor 3, the phase switching pattern is controlled so that the rear wheel steering angle becomes zero and the neutral return is performed. When the signal S3 or S4 becomes high level, the above-mentioned brake signal generating circuit 6
The hardware configuration using the Nos. 7, 68 and the third and fourth relays 75, 76 brakes the motors M1, M2 for a predetermined time. After that, the backup microprocessor 3 performs neutral return.

In this embodiment, the magnetic pole sensor 18 is used as the rotation sensor of the brushless motor, but an encoder such as a light pulse type sensor using a light emitting diode may be used.

In the above embodiment, the current flowing through the motor is large, and the ground levels are different between the FETs of the motor drivers 5 and 6 and the first microprocessor 1, the second microprocessor 2 and the third microprocessor 3 side. In this case, each ground may be provided separately and a ground level correction circuit may be provided in the middle of the signal line.

In this embodiment, the motor is divided into two,
There are two motor drivers. This is so that even if one of the motors or the motor driver fails, the other can be driven to restore the neutral state. When it is determined that the motor M1 system is out of order, for example, when an abnormal current is detected in the motor driver 5 of the motor M1, the relay drive circuit 79 opens the relay 77. Then, the motor M2 may be driven to return to the neutral position. When it is determined that the motor M2 system is out of order, the relay drive circuit 80 opens the relay 78. Then, the motor M1 may be driven to return to the neutral position. In these cases, only one of the motors is driven, so the output is reduced, but neutral return is possible.

In contrast to the present embodiment, the first and second microprocessors are mutually monitored, and the first microprocessor 1 controls the motor M1 and the second microprocessor 2 controls the motor M2. Good. But,
It is difficult to synchronize both. If the synchronization is lost, the motor output will decrease. Therefore, in this embodiment,
The motor is divided into two, and the two motor drivers 5 and 6 that drive each of them are controlled by distributing the output of one microprocessor (first microprocessor 1). Therefore, the two systems of motors can be reliably synchronized.

As described above, in this embodiment, the motors 12, M1, M2, the rear wheel steering mechanism 11 controlled by the rotation of the motors, the motor drivers 5, 6 for independently rotating the motors, and the motor driver are provided. It is connected to a first microprocessor 1 that is a controllable main control means, a backup microprocessor 3 that is a sub-control means that can control a motor driver, a first microprocessor 1, a backup microprocessor 3 and a motor driver. Relays 7 and 8 which are switching means for connecting either one of the microprocessor 1 and the motor driver or between the backup microprocessor 3 and the motor driver, and abnormality detecting means for detecting abnormality of the first microprocessor 1. 2 microprocessors 2, 1st microprocessor A selector 4, which is a selection unit for switching the relays 7 and 8 from the first microprocessor 1 side to the backup microprocessor 3 side when the sessa 1 is abnormal, is provided with the first microprocessor 1 according to the state of the vehicle. While adjusting the corner, the backup microprocessor 3 returns the rear wheel to the neutral position when the first microprocessor 1 is abnormal.

Therefore, when the first microprocessor 1 fails, the rear wheel steering angle can be returned to the neutral position without using the return spring. Therefore, the return spring is not required for the rear wheel steering mechanism 11, the driving torque of the motor 12 can be reduced, and the size can be reduced. In addition, the steering speed can be increased.

In this case, the second microprocessor 2 which is the abnormality detecting means for detecting the abnormality of the first microprocessor 1 judges the abnormality of the first microprocessor 1 by mutual monitoring. May be detected by monitoring the output to the motor driver. In this case, the selector 4, the relay 7,
8,75,76 failures can also be detected.

In this embodiment, the motor 12,
Rear wheel steering mechanism 1 controlled by M1 and M2 and a motor
1, motor drivers 5 and 6 for rotating a motor, relay 7 which is switching means connected to the motor driver,
8. A first microprocessor 1 capable of calculating a steering angle amount of rear wheels according to a vehicle state and controlling a motor driver via the switching means, a second microprocessor 2 performing the same calculation as that of the first microprocessor, A backup microprocessor 3 capable of controlling a motor driver via the relays 7 and 8 and a selector 4 which is a selection unit for switching the relays 7 and 8 are provided. Here, the first microprocessor 1 compares the operation result of the second microprocessor 2 with its own operation result and identifies that either the first microprocessor 1 or the second microprocessor 2 is abnormal. If either of them is abnormal, the first abnormal signal S1 is output. Further, the second microprocessor 2 compares the calculation result of the first microprocessor 1 with the calculation result of its own, and identifies that either the first microprocessor 1 or the second microprocessor 2 is abnormal. If any of them is abnormal, the second abnormality signal S2 is output. Further, the selector 4 switches the relays 7 and 8 from the first microprocessor 1 side to the backup microprocessor 3 side when receiving either one of the first and second abnormality signals.
Further, the backup microprocessor 3 returns the rear wheel to the neutral position when receiving one of the first and second abnormal signals.

Therefore, when the first microprocessor 1 or the second microprocessor 2 fails, the rear wheel steering angle can be returned to the neutral position without using the return spring. Therefore, the rear wheel steering mechanism 11 does not require a return spring. As a result, the motor 12
Driving torque can be reduced, and the size can be reduced. In addition, the steering speed can be increased.

Further, according to the above-described embodiment, the rear wheel steering mechanism 11 includes the rack shaft 25 that steers the rear wheels in accordance with the lateral movement amount, and the pinion 27 that laterally moves the rack shaft 25 by rotation. And fixed to the pinion 27, the motor 1
2 and a hypoid gear 29 having zero reverse efficiency. Therefore, since a hypoid gear having zero reverse efficiency can be used, the brushless motor 12 can be further downsized.

[0073]

As described above, claim 1 or 2
According to the invention, the brushless motor is used, and when the control unit fails, the rear wheel steering angle can be returned to the neutral position without using the return spring. Therefore, the return spring is unnecessary for the rear wheel steering mechanism.
As a result, the driving torque of the motor can be reduced and the size can be reduced. In addition, the steering speed can be increased.

Further, in the invention of claim 3, in addition to the effects of the inventions of claims 1 and 2, since a hypoid gear having zero reverse efficiency can be used, the brushless motor can be further miniaturized.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention.

FIG. 2 is a front view of a rear wheel steering mechanism used in an embodiment of the present invention.

3 is a partial cross-sectional view of the rear wheel steering mechanism of FIG.

4 is a cross-sectional view of the rear wheel steering mechanism of FIG.

FIG. 5 is a sectional view of a motor used in an embodiment of the present invention.

FIG. 6 is a sectional view of a motor used in an embodiment of the present invention.

FIG. 7 is an explanatory view of windings of the motor shown in FIGS.

FIG. 8 is a front view of a magnet used in an example of the present invention.

FIG. 9 is a front view of the substrate of the magnetic pole sensor used in the embodiment of the present invention.

FIG. 10 is an operation explanatory view of the brushless motor of the present invention.

FIG. 11 is a circuit configuration diagram of an electronic control device used in an embodiment of the present invention.

FIG. 12 is a circuit configuration diagram of a driver of the electronic control device of FIG.

13 is a circuit configuration diagram of a selector of the electronic control device of FIG.

14 is a functional block diagram of a microprocessor of the electronic control unit of FIG.

15 is a functional block diagram of a target steering angle calculation unit of the microprocessor of FIG.

16 is a functional block diagram of a motor servo control unit of the microprocessor of FIG.

FIG. 17 is a circuit configuration diagram of a magnetic pole sensor input circuit of the electronic control device of FIG. 11.

FIG. 18 is a flowchart of a magnetic pole sensor abnormality determination unit in FIG.

FIG. 19 is a flowchart of the phase switching control unit in FIG.

FIG. 20 is a flowchart of the open control unit in FIG.

FIG. 21 is a flowchart of the second microprocessor monitoring section of FIG.

22 is a flowchart of the first microprocessor monitoring section of FIG.

23 is a flowchart of the backup microprocessor of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 1st microprocessor (main control means) 2 2nd microprocessor (abnormality detection means) 3 Backup microprocessor (sub control means) 4 Selector (selection means) 5,6 1st, 2nd motor driver (motor driver) 7, 8 First and second relays (switching means) 9 Electronic control device 10 Front wheel steering device 11 Rear wheel steering mechanism 12 Motors 13, 14 Front wheels 15,16 Rear wheels 17,20 First and second front wheel steering angle sensor 18 Magnetic pole sensor 19 Steering wheel 21 Rear wheel steering angle sensor 22, 23 First and second vehicle speed sensor 24 Yaw rate sensor 25 Rack shaft 26 Rack 27 Pinion 28 Boot 29 Gear 30 Pinion 31 Rack guide 32 Rack guide cover 33 Lever 34 pin 35 Hole 36 cover 37 pin 38 housing 39 40 motor housing 41 motor shaft 42 magnet 43 core 43a protrusion 44 motor winding 44a, 44b, 44c, 44d, 44e, 44f winding 45 terminal 46 wire harness 47 holder 48 cover 49 substrate 50 hall IC 51 magnet 52 rotor 53 Ball joint 54 Axis 55,56 First and second constant voltage regulator 57,58 Interface 59 Battery 60,66 Target steering angle calculation unit 61,70 Motor servo control unit 62,71 Phase switching control unit 63,72 Magnetic pole sensor abnormality judgment Part 64,73 Open control part 65 Second microprocessor monitoring part 67,68 Brake signal generating circuit 75 Third relay 76 Fourth relay 74 First microprocessor monitoring part 77,78 Relay 79,80 Relay drive circuit 81 Reverse Phase amount setting unit 82 Steering gain setting unit 83 Yaw rate gain setting unit 84, 85, 95
Accumulation unit 86 Current detection circuit 87,97 Addition unit 90,94 Differentiation unit 88 Abnormal current limit circuit 89 Pulse width modulation signal synthesis circuit 91 Differential gain setting unit 92 Subtraction unit 93 Deviation steering angle dead zone applying unit 96 Proportional unit 98 Deviation steering angle Limiter 99 Pulse width modulation converter 100 Buffer 101 Peak hold circuit AGLA Target rudder angle value AND1, AND
2 AND circuit ANG Control amount COMP1 Comparator D1-8 Diode DAGLA Differential term DR1 Reset signal E2PMAX Predetermined value ETH2 Steering angle deviation value EXOR1, EXOR2 Exclusive OR circuit G11, G21 Gate drive circuit HA, HB, HC
Magnetic pole signal HPID Steering angle value IGA, IGB
Power supply terminal IGSW Ignition switch K1 (V) Steering gain K2 (V) Yaw rate gain L1, L2, L3
Phase switching signal group LA11, LB11, LC11, LA21, LB21,
LC21 Phase switching signal M1, M2 Motor MI1 Peak signal MOC1, MS1
Output signal PGLA Proportional term PH Pattern fuse PIGA, PIGB Power supply terminal PIGM1 Voltage PWM1, PWM2 Pulse width modulation signal RAGL Actual steering angle value ref Reference voltage S1, S2, S3, S4, S5, S6 Signal Rs resistance RV1 Boost voltage value SAGLA Differentiation Value SETH2 Steering angle deviation differential value SW1, SW2 switch TA11, TB11, TC11, TA21, TB21,
TC21 Transistor TC Choke coil U1, V1, W1, U2, V2, W2 terminal V Vehicle speed Vcc1, Vcc
2 Constant voltage YTDIFGAIN Differential gain ΔAGL Steering angle deviation γ Yaw rate value θ1 Reversed phase control amount θ2, θ3 Steering control amount θm Rotation angle θs Steering angle In parentheses, the names of the constitutions of the embodiments correspond to the constitutions and names of the claims. Represents the name of the configuration of the claim in the case of different.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] August 18, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0062

[Correction method] Change

[Correction content]

FIG. 23 is a flow chart showing the operation of the backup microprocessor 3. First, in step 250, the process waits until the signal S3 or S4 becomes low level. When the signal S3 or S4 becomes low level, next, in step 251, the process waits until the timer T becomes 0 or less. The timer T is a timer that counts down every time, and is initially set to a predetermined value. When the timer T becomes 0 or less, in step 252, the next phase switching pattern is set from the map shown in Table 5 above. Next, in step 253, the timer T is set to a predetermined time (for example, 1 second). Step 251
Since step 252 is executed only when the timer T is 0 or less, step 252 is thereafter executed every predetermined time set in the timer T. In step 252, the next value is set according to the current phase switching pattern and the result of comparison between the rear wheel steering angle value θr output from the rear wheel steering angle sensor 21 and the predetermined value A1. Here, the pattern of Table 5 used in the above-mentioned open control unit 64 is used as it is. Therefore, also in the control of the backup microprocessor 3, the phase switching pattern is controlled so that the rear wheel steering angle becomes zero and the neutral return is performed. When the signal S3 or S4 goes low , the motor configuration of the motors M1, M3
Brakes on M2. After that, the backup microprocessor 3 performs neutral return.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Correction target item name] Fig. 23

[Correction method] Change

[Correction content]

FIG. 23

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Fumiaki Ota, Inventor Akira Ota, 2-chome, Asahi-cho, Kariya city, Aichi Aisin Seiki Co., Ltd. (72) Takeshi Hatano, 2-chome, Asahi-cho, Kariya city, Aichi prefecture In Seiki Co., Ltd. (72) Hisayasu Mase, 2-chome, Asahi-cho, Kariya city, Aichi Aisin Seiki Co., Ltd. (72) Aki Sawa, Akira 2-chome, Asahi-cho, Kariya city, Aichi (72) Inventor Hiroshi Nakajima 2-1-1 Asahi-cho, Kariya city, Aichi Prefecture Aisin Seiki Co., Ltd. (72) Inventor Taichi Matsumoto 1-cho, Toyota city, Aichi prefecture Toyota Motor Corporation Within

Claims (3)

[Claims] 1. A motor; a rear wheel steering mechanism controlled by rotation of the motor; a motor driver for independently rotating the motor; a main control unit capable of controlling the motor driver; a sub-control capable of controlling the motor driver. Switching means connected to the main control means, the sub-control means and the motor driver and connecting either the main control means and the motor driver or the sub-control means and the motor driver; and detecting an abnormality of the main control means. An abnormality detection means; a selection means for switching the switching means from the main control means side to the sub control means side when the main control means has an abnormality; and the main control means adjusts the rear wheel steering angle in accordance with the state of the vehicle, The rear wheel steering device, wherein the sub-control means returns the rear wheels to the neutral position when the main control means malfunctions. 2. A motor; a rear wheel steering mechanism controlled by the motor; a motor driver for rotating the motor;
Switching means connected to the motor driver; a first microprocessor capable of calculating the steering angle amount of the rear wheels according to the vehicle state and controlling the motor driver via the switching means;
A second microprocessor for performing the same calculation as the first microprocessor; a backup microprocessor capable of controlling a motor driver via the switching means; a selection means for switching the switching means; and the first microprocessor, The calculation result of the second microprocessor is compared with the calculation result of its own to identify that either the first microprocessor or the second microprocessor is abnormal, and if either is abnormal, the first abnormality Outputting a signal, the second microprocessor compares the operation result of the first microprocessor with its own operation result, and identifies that either the first microprocessor or the second microprocessor is abnormal, If any one of them is abnormal, a second abnormality signal is output, and the selecting means outputs the first abnormality signal. And one of the second abnormal signals, the switching means is switched from the first microprocessor side to the backup microprocessor side, and the backup microprocessor receives one of the first and second abnormal signals. A rear wheel steering device, which, when received, returns the rear wheels to a neutral position. 3. The rear wheel steering mechanism includes a rack shaft that steers rear wheels according to a lateral movement amount, a pinion that laterally moves the rack by rotation, and a pinion that is fixed to the pinion. The rear wheel steering system according to claim 1 or 2, further comprising a hypoid gear having a reverse efficiency of zero.