JPH0579808A - Steering-angle detecting apparatus - Google Patents

Abstract

(57) [Summary] [Purpose] An analog sensor is provided with a rudder angle detection device capable of correcting deviations in detection values due to unavoidable deterioration over time or temperature fluctuations, and high reliability is obtained. In a steering angle detection device having an analog steering angle sensor 17 for detecting a steering angle position and outputting a steering angle signal corresponding to the steering angle position, a pulse signal Z is output at at least one predetermined steering angle position. The steering angle position specifying means 16 and the steering angle signal θFDT output by the analog steering angle sensor 17 when the steering angle position specifying means 16 outputs the pulse signal Z are read, and the correction value δ is calculated from the steering angle signal θFDT. Calculate,
A correction unit 18 that corrects the output signal of the analog steering angle sensor 17 based on the correction value δ is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rudder angle detecting device used in a power steering device or the like, and more specifically to a rudder angle detecting device capable of obtaining high reliability in detecting a rudder angle by an analog rudder angle sensor. Regarding a detection device.

[0002]

2. Description of the Related Art In a recent power steering system, a steering angle detection device detects a steering angle to perform feedback control, and similarly, in a front and rear wheel steering system, a steering angle detection device detects a steering angle of a rear wheel and returns the feedback. Take control. Conventionally, these steering devices use a steering angle detection device that detects a steering angle based on a neutral position by an analog sensor such as a differential transformer and outputs it as an analog signal. The control is based on.

[0003]

However, in the above-described conventional rudder angle detecting device, the analog type sensor such as the differential transformer is easily deteriorated over time and is easily affected by the ambient environment such as temperature. However, there is a problem in that high reliability cannot be expected for the steering angle that is the detected value. The present invention has been made in view of the above problems, and an object of the present invention is to provide a steering angle detection device that can obtain high reliability.

[0004]

In order to achieve the above object, the present invention provides a rudder angle detecting device having an analog rudder angle sensor for detecting a rudder angle position and outputting a rudder angle signal corresponding to the rudder angle position. In the steering angle position specifying means for outputting a pulse signal at at least one predetermined steering angle position, and the steering angle signal output by the analog type steering angle sensor when the steering angle position specifying means outputs a pulse signal. The correction value is calculated from the steering angle signal, and the correction means for correcting the output signal of the analog steering angle sensor based on the correction value is provided.

[0005]

According to the present invention, when the steering angle is specified by the pulse signal, the output signal of the analog steering angle sensor is read to calculate the correction value, and the output signal of the analog steering angle sensor is corrected by this correction value. Therefore, it is possible to reduce the influence of deterioration over time, temperature, etc. on the detected value, and obtain high reliability.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 9 show a front and rear wheel steering device using a steering angle detecting device according to an embodiment of the present invention, FIG. 1 is an overall schematic configuration diagram, FIG. 2 is a block diagram of a control system, FIG. 4, FIG. 5 and FIG. 6 are flowcharts showing the control process, FIGS. 7 and 8 are data tables used for the control process, and FIG. 9 is a diagram for explaining the operation.

As shown in FIG. 1, in this embodiment, the front wheel steering device 12 connected to the steering wheel 11 steers the front wheels 13, and the rear wheel steering device 14 turns the rear wheels 15. Steer. The front wheel steering device 12 has a well-known rack and pinion type steering gear mechanism, and mechanically connects the steering wheel 11 and the front wheels 13.

The steering wheel 11 has a main front wheel steering angle sensor 16 for detecting the steering angle, that is, the steering angle of the front wheels 13, and the front wheel steering device 12 has a sub front wheel steering angle sensor for detecting the steering angle of the front wheels 13. 17 are attached to these sensors 1
6, 17 are connected to the controller 18. In addition,
19a and 19b are vehicle speed sensors, and the vehicle speed sensor 19a
Indicates the rotational speed of each wheel 13, 15, and the vehicle speed sensor 19b detects the rotational speed of the output shaft of the transmission.

The main front wheel steering angle sensor 16 is composed of a digital sensor such as an encoder, and the detection axis maintains a predetermined correspondence with the steering angle (position) of the front wheels. The main front wheel rudder angle sensor 16 has a detection shaft that rotates integrally with the steering shaft, that is, the front wheel turns, and outputs three types of pulse signals of A phase, B phase, and Z phase when the detection shaft rotates. To do.
The main front wheel steering angle sensor 16 outputs the A-phase signal and the B-phase signal in the same cycle and different phases with respect to the rotation of the detection shaft, and outputs the Z-phase signal in a larger cycle, for example, the rotation cycle of the detection shaft. Correspondingly, the Z-phase signal of one pulse is output to the controller 18 for one rotation. The output position of 1 of this Z-phase signal coincides with the neutral position. Although detailed description is omitted, the controller 18 determines the steering angle (speed) by the number of pulses of the A and B phase signals.
Is determined by the phase of the A and B phase signals, and Z
The steering angle position is specified by the phase signal.

The sub-front wheel steering angle sensor 17 is composed of a differential transformer and outputs an analog signal according to the displacement of the rack to the controller 18. This sub-front wheel steering angle sensor 17 is
As is well known, it has a primary coil to which an alternating current is supplied, a core that is displaced integrally with the rack, and a secondary coil connected to the controller 18. This sub-front wheel steering angle sensor 17
Is induced in the secondary coil according to the position of the core,
An analog signal representing the displacement of the rack is output based on this induced voltage. Needless to say, the analog signal output from the sub-front wheel steering angle sensor 17 has a potential corresponding to the displacement of the rack, that is, the steering angle of the front wheels 13, and a polarity corresponding to the turning direction.

The rear wheel steering device 14 has an electric motor 20 as an actuator for steering the rear wheels, and the rotating shaft of the electric motor 20 is connected to the left and right rear wheels 15 via a reversible transmission mechanism such as a ball screw mechanism. .. The electric motor 20 is the controller 1
8 is connected to the rear wheel 1 and fed from the controller 18 to the rear wheel 1.
Steer 5.

The rear wheel steering device 14 is provided with a main rear wheel rudder angle sensor 22 and a sub rear wheel rudder angle sensor 23 for detecting the rudder angle of the rear wheel 15, and the screw of the ball screw mechanism. A spring 21 for biasing the rear wheel 15 to a neutral position on a shaft or the like
Is attached. Similar to the front wheel steering device 12, the main rear wheel steering angle sensor 22 is a digital type consisting of an encoder,
The sub-rear wheel steering angle sensor 23 is configured as an analog type including a differential transformer. These rear wheel steering angle sensors 22 and 23 are connected to the controller 18 and detect the displacement of the screw shaft as the steering angle of the rear wheel 15.

The main rear wheel rudder angle sensor 22 has a detection axis that maintains a predetermined correspondence with the rudder angle of the rear wheel 15 and, in the same manner as the main front wheel rudder angle sensor 16 described above, depending on the rudder angle of the rear wheel 15. A, B,
Outputs Z-phase signal. And this main rear wheel steering angle sensor 2
2 outputs the Z-phase signal at least at the neutral position of the rear wheel 15. Similarly to the sub-front wheel steering angle sensor 17, the sub-rear wheel steering angle sensor 23 also detects the steering angle of the rear wheel 15, that is, the above-described screw shaft displacement and the like, and outputs an analog signal representing the steering angle of the rear wheel. Output. The main rear wheel steering angle sensor 22, in particular, the configuration for outputting the Z-phase signal corresponds to the steering angle position specifying means, and the Z-phase signal corresponds to the pulse signal in the claims.

The controller 18 is, as shown in FIG.
The control unit 24 and the drive unit 25 are connected to each other. The control unit 24 includes a microcomputer 26 having seven interface circuits 27, 28, 29, 30, 31, 32, and 3.
3 are connected by a data bus.

Interface circuits 27, 28, 29, 3
0 and 31 are the above-mentioned sensors 16, 17, 19 and
22 and 23 are connected, a current sensor 34 described later is connected to the interface circuit 32, and a voltage sensor 35 described later is connected to the interface circuit 33.

The microcomputer 26 includes a drive unit 25.
And outputs the control signals g, h, i, j to the drive unit 25. This microcomputer 26 has sensors 16, 17, 19, 22, 2 as described later in detail.
The output signals of 3, 34, and 35 are arithmetically processed to calculate the rear wheel target steering angle, and the control signals g, h, i of the duty factor corresponding to the deviation between the rear wheel target steering angle and the rear wheel actual steering angle are calculated. Output j.

The drive unit 25 includes a gate drive circuit 36,
Motor drive circuit 37, relay 38 and current sensor 34
Have. The gate drive circuit 36 includes a booster circuit and the like, is connected to the microcomputer 26, and is also connected to the motor drive circuit 37. This gate drive circuit 36
Outputs to the motor drive circuit 37 a drive signal according to the duty factor of the control signals g, h, i, j input from the microcomputer 26.

The motor drive circuit 37 is constituted by connecting four field effect transistors (FETs) Q1, Q2, Q3 and Q4 in a bridge shape, and a battery plus (not shown),
It is installed between the negative terminals. This motor drive circuit 37
Is connected to the positive terminal of the battery via a normally open contactor of the relay 38, and the current sensor 34 is provided between the negative terminal of the battery and
Source-drain connection part of FETQ1 and FETQ3 and F
The terminal of the electric motor 20 is connected between the ETQ2 and the source / drain connection of the FETQ4.

Further, this motor drive circuit 37 is
The gate of T is connected to the gate drive circuit 36, and a drive signal is input from the gate drive circuit 36 to these FETs. These FETs are turned on / off to energize the electric motor 20 according to the duty factor of the drive signal input to the gate, and the FETs Q2 and Q4 are turned on to turn on the electric motor 20.
Power generation braking is performed. A drive signal having a duty factor corresponding to the control signal g is input to the FET Q1, a control signal h is input to the FET Q2, a control signal i is input to the FET Q3, and a drive signal corresponding to the control signal j is input to the FET Q4. ..

The relay 38 has the above-described normally open contactor and solenoid, and the solenoid is connected to the relay drive circuit 39. The relay drive circuit 39 is connected to the microcomputer 26, and energizes the solenoid of the relay 38 according to the control signal output from the microcomputer 26. In this relay 38, the solenoid is energized to close the contactor in a normal state, and the solenoid is deenergized to open the contactor in an abnormal state. The current sensor 34 detects a current flowing through the motor drive circuit 37, that is, a current flowing to the electric motor 20.

The electric motor 20 has a rotor having a winding on its rotating shaft, a magnet provided on the stator, and the rotating shaft connected to the rear wheel 15 as described above. This electric motor 20 comprises two sets of brushes, and both terminals of the winding are connected to the above-mentioned motor drive circuit 37 via one set of brushes and to the short circuit 40 in parallel via another set of brushes. ing.

The short-circuit 40 has two short-circuit damper relays 41 and 42, and each of these damper relays 41 and 42 is composed of a normally-closed contactor and a solenoid. In the relays 41 and 42, the contactors 41a and 42a are connected in series between both terminals of the electric motor 20, and the above-mentioned voltage sensor 35 is connected between the respective contactors. The voltage sensor 35 detects the potential between the contactors.

In the damper relays 41 and 42, solenoids are connected in series, and one end of the solenoid of one relay 41 is connected to the damper relay drive circuit 43 and the other relay 42 is connected.
One end of the solenoid is connected to the damper relay drive circuit 44, and the solenoids are connected to a negative (ground) terminal common to the motor drive circuit 37. The damper relay drive circuits 43 and 44 are respectively the microcomputer 2
6 and energizes the solenoid based on a control signal output from the microcomputer 26.

Next, the operation of this embodiment will be described. This four-wheel steering system executes the system start program shown in the flowchart of FIG. 3 at the start of system operation such as when the ignition switch is turned on, and the system end program shown in the flowchart of FIG. 4 at the time of turning off the ignition switch. To do. Then, the steering angle control program shown in the flowchart of FIG. 5 is repeatedly executed by the microcomputer 26 to control the steering angle of the rear wheels 15.

First, explaining the system start program, as shown in FIG. 3, the backup data of the three correction values stored in the non-volatile memory is read in step P1, and these three backup data are read in step P2. Judge whether or not they match. And these 3
If the two backup data match, step P
In step 3, the flag F is set to 0. If the three backup data do not match, all the backup data are erased in step P4, and then the flag F is set to 1 in step P5.

On the other hand, in the system termination program, as shown in FIG. 4, three data storage addresses are generated by turning off the ignition key in step P1.
In the next step P2, the correction value is stored in each of the three locations specified by the memory address. The stored correction value uses the same data and is read by the system start program as described above.

In the steering angle control program,
As shown in FIG. 5, in step P1, the front wheel steering angle θf, the rear wheel steering angle θr, the vehicle speed V, and the like are read from the output signals of the respective sensors, the failure of each sensor is diagnosed, and the sub-front wheel steering angle sensor 17 and the sub-wheel are detected. Output correction processing with the rear wheel steering angle sensor 23 is performed.
Then, in the failure diagnosis, if it is determined that there is a failure, the failure flag is set to 1, and the output correction process will be described with reference to FIG.
The correction program is executed. The detailed description of the failure diagnosis is omitted.

Next, in step 2, the steering angle ratio k is set using the vehicle speed V as an address using the data table 1 shown in FIG.
Search the map. Then, in step 3, the front wheel steering angle θf detected by the front wheel steering angle sensors 16 and 17 is multiplied by the steering angle ratio k to obtain the rear wheel target steering angle θrt.

Subsequently, in step 4, a deviation Δθr between the actual rear wheel steering angle θr detected by the rear wheel steering angle sensors 22 and 23 and the rear wheel target steering angle θrt is calculated. Next, in step 5, using the data table 2 shown in FIG.
The duty factor D is map-searched using the deviation Δθr as an address.

In step 6, it is determined whether the value of the failure flag F, that is, the failure state. And normal (F =
If 0), in step 7, the duty factors of the signals g, h, i, j are changed to the steering direction (R, L, Center).
It is set as shown in Table 1 according to r). Therefore, the rear wheels 15 are steered to the target steering angle by the electric motor 20. However, the steering direction (Center) indicates a state in which the current steering angle is maintained.

[0031]

[Table 1]

When it is determined in step 6 that the failure (G = 1), the energization of the relay 38 is stopped in step 8 to disconnect the motor drive circuit 37, that is, the electric motor 20 from the battery. Then, in step 9, it is determined whether or not the drive unit 25 of the controller 18, for example, the motor drive circuit 37 is in failure.
The duty factors of h, i, j are all zero, and if normal, in step 11, the signals g, h are zero, and the signals i, j are zero.
Is set to 1. Therefore, the electric motor 20 can be disconnected from the battery when a failure occurs.

Here, in the output correction process of the auxiliary front wheel steering angle sensor 17, as shown in FIG. 6, the front wheel actual steering angle θFDT is read from the output signal of the auxiliary front wheel steering angle sensor 17 in step P1, and the front wheels are read in step P2. The corrected steering angle θFD is obtained by subtracting the correction value δz from the actual steering angle θFDT. This correction value δz
Is the value read by the system start program at the time of the first routine execution after the execution of the system start program described above, and when it is erased (when the flag F is 1), 0 is set as a temporary value. Adopted. As described above, the steering angle value used in the steering angle control program shown in FIG. 5 is determined with the corrected steering angle θFD set to θf.

Next, at step P3, since correct correction cannot be made unless the neutral position is known, it is determined whether or not the main rear wheel steering angle sensor 16 has output the Z-phase signal, and the Z-phase signal is output. If so, the process from step P4 is performed, and if the Z-phase signal is not output, the process from step P8 is performed. As described above, the Z-phase signal outputs one pulse at the neutral position of the front wheel 13, and in other regions, one pulse is output for each steering angle according to the rotation of the detection shaft of the main front wheel steering angle sensor 16. ..

In step P4, the value of the flag F is determined, and if the flag F is 0, the magnitude of the turning speed of the front wheels 13 is determined in step P5. If the flag F is 1, the processing from step P7 onward is performed. To execute. In this step P4,
If the backup data is reliable, the correction can be performed with higher accuracy, and if the backup data is not available, the correction value is set earlier.

In step P5, when the turning speed is high, the output difference between the main and sub front wheel steering angle sensors 16 and 17 may occur due to backlash and twist of the front wheel steering device 12,
In order to eliminate this, if the turning speed θ'f of the front wheels 13 is greater than or equal to the predetermined value θ'a, step P8 and subsequent steps are performed. If the turning speed θ'f of the front wheels 13 is less than the predetermined value θ'a, step P
The process of 6 is performed. The steered speed θ'f of the front wheels 13 in step P5 can be obtained from the output of the main front wheel steering angle sensor 16 or by the differential operation of the output of the sub front wheel steering angle sensor 17.

At step P6, whether or not the corrected steering angle θFD is within a predetermined value range (a <θFD <b, see FIG. 9) to check whether or not the value shows a large fluctuation due to noise or the like. Is determined, and if it is within the predetermined value range (a <θFD <b), the process of step P7 is performed, and the predetermined value range (a <θ
If it is not within FD <b), the processes after step P8 are performed.
In Step P7, the correction value δ is calculated and updated based on the following equation from the front wheel actual steering angle θFDT and the correction value δz calculated by executing the previous routine. In the following equation, k is a constant in the range of 0 to 1 for weighting. δ ← k * θFDT + (1-k) * δz

Next, in step P8, the flag F
Value is judged, and if the flag F is 0, the step P1 is executed again.
1 is executed, and if the flag F is 1, step P9
Then, it is determined whether the correction value δ exceeds a predetermined reference value γ * θFDT. As a result, the correction value can be set early when there is no backup data, and more accurate correction can be switched when the correction value is set. In step P8, the reference value γ * θFDT is set to the actual front wheel steering angle θF.
The value is determined as a value obtained by multiplying DT by a predetermined coefficient γ, but it may be a value that is not affected by the front wheel actual steering angle θFDT or the like.

If it is determined in step P9 that the correction value δ is greater than or equal to the reference value γ * θFDT, the flag F is set to 0 in step P10, and the correction value δ is set to the reference value γ * θFD.
If it is smaller than T, the correction value δ is prepared for the next routine execution in step P11 without performing the process of step P10.
Is stored as the value Δz.

As is apparent from the above-mentioned figures, in this embodiment, based on the actual steering angle θFDT detected by the auxiliary rear wheel steering angle sensor 23 every time the main rear wheel steering angle sensor 22 outputs the Z-phase pulse signal. The correction value δz is updated, and the output value of the sensor 22 is corrected based on this correction value δz. Therefore, as shown in FIG. 9, when the neutral position of the rear wheels 15 is used as a reference, even if the actual steering angle θFDT as the detection value by the auxiliary rear wheel steering angle sensor 23 deviates from the true value, the Z phase With the output of the pulse signal, the corrected steering angle value θFD can approach the neutral position, that is, the true steering angle value, and substantially match. Therefore, it is possible to reliably correct the shift due to deterioration over time and temperature fluctuations.
High reliability can be obtained.

In the above embodiment, the steering angle of the front wheels 13 will be described, but it goes without saying that the present invention can be applied to the rear wheels 15. In the above-described embodiment, the Z-phase signal output at the neutral position is used as a reference, but a pulse signal or the like output at a predetermined steering angle may be used instead of the Z-phase signal.

[0042]

As described above, according to the steering angle detecting device of the present invention, when the steering angle is specified, the output signal of the steering angle sensor is read and the correction value is calculated from the read output signal, Since the output signal of the steering angle sensor is corrected by this correction value, the deviation of the signal due to deterioration over time or temperature fluctuation can be effectively corrected, and high reliability can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a front and rear wheel steering device to which a steering angle detection device according to an embodiment of the present invention is applied.

FIG. 2 is a block diagram of a control system of the front and rear wheel steering device.

FIG. 3 is a flowchart showing a control process of the front and rear wheel steering device.

FIG. 4 is a flowchart showing a control process of the front and rear wheel steering device.

FIG. 5 is a flowchart showing a control process of the front and rear wheel steering device.

FIG. 6 is a flowchart showing a control process of the front and rear wheel steering device.

FIG. 7 is a data table used for control processing of the front and rear wheel steering device.

FIG. 8 is a data table used for control processing of the front and rear wheel steering device.

FIG. 9 is a view for explaining the operation of the steering angle detection device.

[Explanation of symbols]

11 ... Steering handle, 12 ... Front wheel steering device, 13 ...
Front wheel, 14 ... Rear wheel steering device, 15 ... Rear wheel, 16 ... Main front wheel steering angle sensor, 17 ... Sub front wheel steering angle sensor, 18 ... Controller, 20 ... Electric motor, 22 ... Main rear wheel rudder angle sensor, 23 ... Sub rear wheel rudder angle sensor, 24 ... Control unit, 25 ...
-Drive unit, 26 ... Microcomputer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukihiro Fujiwara 1-4-1, Chuo, Wako-shi, Saitama Stock Research Institute Honda Technical Research Institute

Claims (1)

[Claims] 1. A steering angle detection device having an analog steering angle sensor for detecting a steering angle position and outputting a steering angle signal corresponding to the steering angle position, wherein a pulse signal is output at at least one predetermined steering angle position. A steering angle position specifying means and a steering angle signal output by the analog steering angle sensor when the steering angle position specifying means outputs a pulse signal, calculates a correction value from the steering angle signal, and based on this correction value And a correction unit that corrects the output signal of the analog type steering angle sensor.