JP2011201366A - Controller for vehicle - Google Patents

Abstract

A steering reaction force transmitted from a steered wheel is quickly and accurately estimated.
[Solution]
A rudder angle varying means (200) capable of changing the rudder angle of at least one of the front wheels and the rear wheels, and a braking / driving force difference between the left and right wheels in at least one of the front wheels and the rear wheels can be varied. An apparatus (100) for controlling a vehicle (10) provided with braking / driving force varying means (600) includes setting means for setting a plurality of target state quantities corresponding to the target motion state of the vehicle, and the motion state of the vehicle. The motion control means for controlling the steering angle variable means and the braking / driving force variable means according to the set target state quantities and the set target state quantities are set so as to be in the target motion state. Steering reaction force based on a plurality of factors among the at least one steering angle according to the plurality of target state quantities and the braking / driving force difference between the left and right wheels at the at least one according to the plurality of set target state quantities. Estimate ; And a constant means.
[Selection] Figure 2

Description

  The present invention includes, for example, EPS (Electronic Control Power Steering), VGRS (Variable Gear Ratio Steering), ARS (Active Rear Steering), 4WS (4 Wheels). The present invention relates to a technical field of a vehicle control device for controlling a vehicle equipped with Steering: four-wheel steering device) or SBW (Steering By Wire: electronically controlled steering angle variable device).

  As this type of device, a method of controlling an automatic steering device including a motor 1 for controlling a steering angle and a motor 2 for controlling a steering torque has been proposed (for example, see Patent Document 1). According to the control method of the automatic steering device disclosed in Patent Document 1, it is supposed that the steering reaction force generated by the automatic steering can be canceled by the torque of the motor 2.

  It has been proposed to control the braking / driving force of each wheel so that the yaw rate of the vehicle becomes the target yaw rate (see, for example, Patent Document 2).

JP-A-6-336169 JP-A-3-292221

  According to the method of Patent Document 1, the assist torque for canceling the steering reaction force is calculated based on the steering torque detected according to the steering reaction force. In other words, the steering reaction force is estimated after becoming manifest as a detectable steering torque.

  That is, in the method of Patent Document 1, the steering reaction force can be detected without being canceled over a significant period that can be perceived by the driver due to the fact that the steering reaction force can only be detected as an actual phenomenon. There is a problem.

  Such a technical problem can occur in the same manner when the technique disclosed in Patent Document 2 that does not describe or suggest the steering reaction force is applied.

  The present invention has been made in view of the above-described problems, and provides a vehicle control device capable of quickly and accurately estimating a steering reaction force transmitted from a steered wheel when various types of automatic steering are performed. Is an issue.

  In order to solve the above-described problem, the vehicle control device according to the present invention changes the rudder angle of at least one of the front wheels and the rear wheels independently of a driver operation that prompts the change of the at least one rudder angle. An apparatus for controlling a vehicle comprising: a rudder angle varying means capable of adjusting a braking / driving force varying means capable of changing a braking / driving force difference between left and right wheels of at least one of a front wheel and a rear wheel; Setting means for setting a plurality of target state quantities corresponding to the target motion state of the vehicle, and the rudder according to the set plurality of target state quantities so that the motion state of the vehicle becomes the target motion state A motion control means for controlling the angle varying means and the braking / driving force varying means, each of the plurality of set target state quantities, the at least one steering angle corresponding to the plurality of set target state quantities, and the Setting A steering device from a steered wheel in a process in which the motion state of the vehicle converges to the target motion state based on a plurality of factors in the braking / driving force difference between the left and right wheels in the at least one according to the plurality of target state quantities And an estimation means for estimating a steering reaction force transmitted to the vehicle.

  The vehicle according to the present invention includes a rudder angle varying unit and a braking / driving force varying unit.

  The rudder angle varying means is a means capable of changing the rudder angle of the front wheels and / or the rear wheels independently of the driver operation that promotes these changes. This driver operation preferably means an operation of various steering input means such as a steering wheel. Therefore, according to the rudder angle varying means, it is possible to change the rudder angle to a desired value even if the driver releases his hand from the steering wheel or only holds the steering. is there.

  That is, the steering angle varying means is essentially different from a normal steering mechanism that takes a mechanical transmission path of steering input from the steering input means to the steered wheels (preferably, the front wheels). However, from the viewpoint of physical configuration, at least a part of the steering angle varying means may naturally be shared or shared with this type of steering mechanism. As a suitable form, the steering angle varying means can take various practical aspects such as VGRS, SBW, ARS, or 4WS.

  According to the rudder angle varying means, the rudder angle is variable in at least a certain range for a wheel (which may include a steered wheel mechanically coupled to the steering input means) as a steering angle control target. Specifically, the traveling direction of the vehicle can be changed regardless of the driver's steering input.

  The braking / driving force varying means is a means capable of changing the braking / driving force difference between the left and right wheels on the front wheel, the rear wheel, or both. The braking / driving force variable means is, for example, various driving force distribution means such as a driving force distribution differential mechanism, various ECB (Electronic Controlled Braking System) including ABS (Antilock Braking System), etc. And so on.

  In the former, torque supplied from various power sources such as an internal combustion engine (note that torque and driving force may have a unique relationship) is distributed in a desired proportion by physical, mechanical, or electrical action. Accordingly, the absolute value of the driving force of the left and right wheels can be controlled to increase or decrease. Therefore, the control target of the braking / driving force varying means adopting this kind of aspect is the driving wheel of the vehicle.

  On the other hand, the latter is equivalent to relatively increasing the driving force of the wheel having the smaller braking force applied by changing the braking force applied to the left and right wheels, preferably as a friction braking force. The effect is obtained. That is, the braking force is a negative driving force. Therefore, the control target of the braking / driving force varying means adopting this kind of mode is not necessarily the driving wheel.

  When a braking / driving force difference occurs between the left and right wheels, the vehicle must have a smaller driving force (braking force) on the side of the wheel having a relatively small driving force (a wheel having a relatively large braking force). Turn to the right (if it is larger).

  Therefore, according to the braking / driving force varying means, it is theoretically possible to change the traveling direction of the vehicle regardless of the steering input of the driver.

  The vehicle control device according to the present invention is a device for controlling such a vehicle, for example, one or a plurality of CPUs (Central Processing Units), MPUs (Micro Processing Units), various processors or various controllers, or further, Various processing units such as a single or multiple ECUs (Electronic Controlled Units) and various controllers, which may appropriately include various storage means such as ROM (Read Only Memory), RAM (Random Access Memory), buffer memory or flash memory. Alternatively, various computer systems such as a microcomputer device may be employed.

  According to the vehicle control device of the present invention, during the operation, a plurality of target state quantities corresponding to the target motion state of the vehicle are set by the setting means.

  The “target movement state” according to the present invention is a movement state to be taken by the vehicle, and at least the above-described difference between the steering angle and the braking / driving force controlled by each of the steering angle varying means and the braking / driving force varying means. It means a movement state that can be guided by change.

  As described above, both the rudder angle varying means and the braking / driving force varying means are means capable of controlling the turning behavior of the vehicle. Therefore, the target motion state of the vehicle according to the present invention means, as a preferred embodiment, traveling while maintaining the target lane, traveling following the target route, and the like.

  The “target state quantity” according to the present invention is a state quantity of the vehicle corresponding to such a target motion state, and is a state quantity that defines the turning behavior of the vehicle. The target state quantity is, for example, a vehicle body slip angle (an angle with respect to the turning tangential direction of the vehicle, which is an angle between the vehicle body direction and the instantaneous traveling direction of the vehicle body), yaw rate, lateral acceleration, etc. Means the target value.

  The setting means defines, for example, a positional state deviation as a physical quantity that can be a reference value for traveling the vehicle along the target travel path (that is, a relative positional relationship between the target travel path to be maintained and the vehicle). As a preferred embodiment, the target state quantity is set based on the deviation of the lateral position of the vehicle relative to the target travel path, the yaw angle deviation, and the like, and the vehicle speed at that time. The target state quantity may be mapped and stored in advance in the form associated with the parameter value in the appropriate storage means, or may be derived according to the appropriate calculation algorithm or calculation formula each time.

  When the target state quantity is set in this way, the steering angle varying means described above according to the plurality of set target state quantities so that the motion state of the vehicle becomes the target motion state by the motion control means. And the braking / driving force varying means is controlled.

  As a result, for example, the travel path of the vehicle is changed to the target travel path by a change in the steering angle prompted by the steering angle varying means, a braking / driving force difference between the left and right wheels prompted by the braking / driving force varying means, or both. Maintaining, converging or asymptotically, the motion state of the vehicle is maintained, converged or asymptotic to the target motion state.

  Here, a plurality of vehicle state quantities are required to maintain, converge or asymptotically maintain the vehicle motion state at the target motion state, but the degree of freedom in stabilizing the vehicle behavior, maintaining drivability, and controlling the behavior, etc. Considering this, it is desirable that the plurality of state quantities can be independently controlled.

  The correlation between the target state quantity and the control amounts of the steering angle variable means and the braking / driving force variable means can be derived from a known equation of motion. At this time, from the viewpoint of independently controlling the vehicle state quantity, parameters including the front wheel steering angle, the rear wheel steering angle, the front wheel braking / driving force difference, and the rear wheel braking / driving force difference must inevitably maintain independence. The same number of state quantities is required. Therefore, if it is intended to define the motion state of the vehicle with two degrees of freedom, two parameters are also required.

  By the way, in this kind of motion control accompanied with behavior change in the yaw direction, various steering devices (including steering input means such as a steering wheel) that physically transmit steering input to the steering wheel from the steering wheel are used. For example, a steering reaction force including that resulting from the self-aligning torque of the steered wheels (if defined as torque, that is, the steering reaction force torque) is applied.

  This steering reaction force can be said to be a “responsiveness” of the steering if the driver holds the steering input means, but the vehicle motion control by the motion control means is performed regardless of the driver's steering intention. (Needlessly, the control itself is a property started by the driver's intention), and such a steering reaction force tends to give the driver a sense of incongruity.

  This steering reaction force is a reaction force that tries to rotate the steering input means in the direction opposite to the original turning direction. When the input unit is turned in the reverse turning direction, the progress of the behavior control by the motion control unit is affected.

  In this case, for example, a steering force that antagonizes the steering reaction force may be separately applied through the application of a steering torque other than the driver steering torque, but if the essential steering reaction force remains unknown, It is difficult to give a force that truly antagonizes this steering reaction force. In addition, if this kind of antagonistic force is large with respect to the steering reaction force, the vehicle is encouraged to turn in the direction of this antagonistic force, and conversely if small, the vehicle is encouraged to turn in the direction of this steering reaction force. Therefore, from the viewpoint of smooth behavior control of the vehicle, there is a situation where it is desired to estimate the steering reaction force with high accuracy.

  That is, in order to realize high-quality automatic steering, in particular, free-running driving by independently controlling a plurality of state quantities in the vehicle, it is an essential requirement to estimate the steering reaction force at least quickly and with high accuracy. The vehicle control device according to the present invention has been conceived of such a problem, and has newly found that it is possible to quickly and highly accurately estimate the steering reaction force based on the above equation of motion. It is.

  In other words, according to the vehicle control apparatus of the present invention, the estimation means includes each of the plurality of set target state quantities, the steering angle corresponding to the plurality of set target state quantities, and the plurality of set target states. A steering reaction force is estimated based on a plurality of factors in the braking / driving force difference corresponding to the amount.

  Here, when it is only necessary to give independent degrees of freedom to the plurality of target state quantities described above, the parameters to be controlled by the motion control means may be the same number as the target state quantities. However, if the steering reaction force is handled as a kind of state quantity, at least three types of parameters are required to estimate the steering reaction force.

  In particular, these three types of parameters are necessary for specifying the relative relationship between the steering reaction force and the plurality of elements, and when such a relative relationship is stored as a reference value so that it can be referred to. The estimation means selects the steering response based on at least two kinds of parameters selected from these at least three kinds of parameters or determined in advance as corresponding to the control target of the movement control means and the relative relationship. The force can be estimated.

  Thus, according to the estimation means, unlike the case of the above-described prior art, unlike the case where the steering reaction force is detected after being manifested over a finite period that cannot be ignored as an actual phenomenon, a plurality of target state quantities or , A plurality of parameters appropriately controlled according to the plurality of target state quantities (for example, from the front wheel steering angle, the rear wheel steering angle, the front wheel braking driving force difference and the rear wheel braking driving force difference in advance or each time A stage before the steering reaction force is actually transmitted to the steering device (preferably a stage before transmission to the steering input means) based on factors that generate the steering reaction force, such as a plurality of parameters selected as appropriate. ) Can complete the estimation of the steering reaction force.

  Therefore, when appropriate steering reaction force suppression measures are requested, predictive suppression (that is, feedforward suppression) is possible, and reactive control (that is, feedback suppression) is performed. In comparison, the practical benefits are clearly significant.

  Supplementally, in the present invention, (1) steering reaction force in realizing desirable yaw behavior control (for example, lane keeping traveling or target route keeping traveling) of the vehicle while coordinating the steering angle varying means and the braking / driving force varying means. (2) From the known equation of motion, the relationship between the steering reaction force and the element value corresponding to the yaw behavior control (target state amount or actual control amount of the steering angle or braking / driving force difference) By focusing on the point that can be derived, it is possible to quickly and highly accurately estimate the steering reaction force. Therefore, it is clear that whether the basis for deriving the steering reaction force lies in a known equation of motion does not have any influence on the inventive step of the present invention.

  In one aspect of the vehicle control device according to the present invention, the target state quantity is a yaw rate and a vehicle body slip angle of the vehicle, and the estimation means is based on the yaw rate and the vehicle body slip angle as the plurality of elements. To estimate the steering reaction force.

  According to this aspect, it is possible to estimate the steering reaction force when the yaw rate and the vehicle body slip angle as the target state quantities are set. Therefore, the estimation of the steering reaction force is performed more quickly, and for example, it is possible to obtain a time delay for taking various measures for suppressing or eliminating the steering reaction force.

  In another aspect of the vehicle control apparatus according to the present invention, the estimation means includes the steering reaction based on the at least one steering angle and the braking / driving force difference between the left and right wheels at the at least one. Estimate force.

  When the motion control means controls the rudder angle varying means and the braking / driving force varying means, the target value of the control amount of each of these means is appropriately set according to the set target state quantity. Here, since the set target value is only the target value, when the steering reaction force is estimated based on the target state quantity, the vehicle motion state is determined by the time delay of the actual response of each means. In a transitional period that deviates from the motion state, the estimated steering reaction force may deviate from the steering reaction force that occurs as an actual phenomenon.

  According to this aspect, the steering reaction force is estimated based on at least one steering angle and the braking / driving force difference between the left and right wheels in at least one, which are actual vehicle behaviors. Therefore, the estimated steering reaction force becomes a value in accordance with the actual behavior of the vehicle, and high estimation accuracy is ensured.

  In another aspect of the vehicle control device according to the present invention, the vehicle includes a steering reaction force suppressing unit capable of suppressing the steering reaction force, and the vehicle control device suppresses the estimated steering reaction force. As described above, steering reaction force control means for controlling the steering reaction force suppression means is provided.

  According to this aspect, the vehicle is provided with the steering reaction force suppression means capable of suppressing the steering reaction force, and the steering reaction force control means suppresses the steering reaction force through the control of the steering reaction force suppression means. Therefore, when the vehicle motion state is maintained, converged, or asymptotically maintained at the target motion state, so-called hand-off travel is possible, and high convenience is provided. Further, even when the hand-off traveling is not performed, it is not necessary for the driver to apply a steering holding force that resists a steering reaction force unrelated to his / her own steering intention, so that a decrease in drivability can be suppressed.

  The “steering reaction force suppressing means” according to the present invention refers to various powers such as EPS that can provide steering torque independent of driver steering torque as one form of steering input given through the steering input means. It may be a steering device.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

1 is a schematic configuration diagram conceptually illustrating a configuration of a vehicle according to an embodiment of the present invention. 2 is a flowchart of LKA control performed in the vehicle of FIG.

Hereinafter, an embodiment according to a vehicle control device of the present invention will be described with reference to the drawings as appropriate.
<Embodiment>
<Configuration of Embodiment>
First, with reference to FIG. 1, the structure of the vehicle 10 which concerns on one Embodiment of this invention is demonstrated. FIG. 1 is a schematic configuration diagram conceptually showing the basic configuration of the vehicle 10.

  In FIG. 1, a vehicle 10 is an example of a “vehicle” according to the present invention that includes a pair of left and right front wheels FL and FR as steering wheels. The vehicle 10 includes an ECU 100, a VGRS actuator 200, a VGRS driving device 300, an EPS actuator 400, an EPS driving device 500, and a braking device 600.

  The ECU 100 is an electronic control unit that includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory) (not shown) and is configured to be able to control the entire operation of the vehicle 10. This is an example of a “vehicle control device”. The ECU 100 is configured to be able to execute LKA control described later in accordance with a control program stored in the ROM.

  The ECU 100 is an integrated electronic control unit configured to function as an example of each of “setting means”, “motion control means”, “estimation means”, and “steering reaction force control means” according to the present invention. The operations related to these means are all configured to be executed by the ECU 100. However, the physical, mechanical, and electrical configurations of each of the units according to the present invention are not limited to this. For example, each of these units includes a plurality of ECUs, various processing units, various controllers, a microcomputer device, and the like. It may be configured as various computer systems.

  In the vehicle 10, a steering input given from a driver via a steering wheel 11 as a steering input unit according to the present invention is connected to the steering wheel 11 so as to be coaxially rotatable and can rotate in the same direction as the steering wheel 11. The upper steering shaft 12 is transmitted. The upper steering shaft 12 is connected to the VGRS actuator 200 at its downstream end.

  The VGRS actuator 200 is an example of the “steering force applying means” according to the present invention, which includes a housing 201, a VGRS motor 202, and a speed reduction mechanism 203.

  The housing 201 is a housing of the VGRS actuator 200 that houses the VGRS motor 202 and the speed reduction mechanism 203. The downstream end of the above-described upper steering shaft 12 is fixed to the housing 201, and the housing 201 can rotate integrally with the upper steering shaft 12.

  The VGRS motor 202 is a DC brushless motor having a rotor 202a serving as a rotor, a stator 202b serving as a stator, and a rotating shaft 202c serving as an output shaft for driving force. The stator 202b is fixed inside the housing 201, and the rotor 202a is rotatably held inside the housing 201. The rotating shaft 202c is fixed so as to be coaxially rotatable with the rotor 202a, and its downstream end is connected to the speed reduction mechanism 203.

  The speed reduction mechanism 203 is a planetary gear mechanism having a plurality of rotational elements (sun gear, carrier, and ring gear) that can be differentially rotated. Among the plurality of rotating elements, the sun gear that is the first rotating element is connected to the rotating shaft 202 c of the VGRS motor 202, and the carrier that is the second rotating element is connected to the housing 201. A ring gear as a third rotating element is connected to the lower steering shaft 13.

  According to the speed reduction mechanism 203 having such a configuration, the rotation speed of the upper steering shaft 12 (that is, the rotation speed of the housing 201 connected to the carrier) corresponding to the operation amount of the steering wheel 11 and the rotation of the VGRS motor 202. The rotation speed of the lower steering shaft 13 connected to the ring gear, which is the remaining one rotation element, is uniquely determined by the speed (that is, the rotation speed of the rotary shaft 202c connected to the sun gear). At this time, the rotational speed of the lower steering shaft 13 can be controlled to increase / decrease by controlling the rotational speed of the VGRS motor 202 to increase / decrease by the differential action between the rotating elements. That is, the upper steering shaft 12 and the lower steering shaft 13 can be rotated relative to each other by the action of the VGRS motor 202 and the speed reduction mechanism 203. Further, due to the configuration of each rotary element in the speed reduction mechanism 203, the rotation speed of the VGRS motor 202 is transmitted to the lower steering shaft 13 in a state where the speed is reduced according to a predetermined reduction ratio determined according to the gear ratio between the respective rotary elements. The

  Thus, in the vehicle 10, the upper steering shaft 12 and the lower steering shaft 13 can be rotated relative to each other, so that the steering angle MA that is the amount of rotation of the upper steering shaft 12 and the amount of rotation of the lower steering shaft 13 are determined. The steering transmission ratio K, which is uniquely determined (which also relates to the gear ratio of a rack and pinion mechanism described later) and the steering angle δf of the front wheel as the steering wheel, is continuously variable within a predetermined range.

  In other words, the VGRS actuator 200 is an example of the “steering angle varying means” according to the present invention that can change the steering angle of the steered wheels independently of the steering input via the steering wheel 11.

  Note that the speed reduction mechanism 203 is not limited to the planetary gear mechanism exemplified here, but is connected to other modes (for example, the upper steering shaft 12 and the lower steering shaft 13 are connected to gears having different numbers of teeth and partially contact each gear. An aspect in which a flexible gear is installed and the upper steering shaft 12 and the lower steering shaft 13 are rotated relative to each other by rotating the flexible gear with a motor torque transmitted via a wave generator. The planetary gear mechanism may have a physical, mechanical, or mechanical aspect different from the above.

  The VGRS driving device 300 is an electric driving circuit including a PWM circuit, a transistor circuit, an inverter, and the like that are configured to be energized to the stator 202b of the VGRS motor 202. The VGRS driving device 300 is electrically connected to a battery (not shown), and is configured to be able to supply a driving voltage to the VGRS motor 202 with electric power supplied from the battery. Further, the VGRS driving device 300 is electrically connected to the ECU 100, and its operation is controlled by the ECU 100. The VGRS driving device 300, together with the VGRS actuator 200, constitutes an example of “steering angle varying means” according to the present invention.

  The rotation of the lower steering shaft 13 is transmitted to the steering mechanism 19.

  The steering mechanism 19 is a so-called rack and pinion mechanism, and includes a pinion gear 14 connected to the downstream end of the lower steering shaft 13 and a rack bar 15 formed with gear teeth that mesh with gear teeth of the pinion gear. Mechanism. The steering mechanism 19 converts the rotation of the pinion gear 14 into a horizontal movement of the rack bar 15 in the drawing, and thereby a steering force via tie rods and knuckles (not shown) connected to both ends of the rack bar 15. Is transmitted to each steered wheel.

  The EPS actuator 400 includes an EPS motor as a DC brushless motor including a rotor (not shown) that is a rotor with a permanent magnet and a stator that is a stator that surrounds the rotor. It is an example of “reaction force suppressing means”.

  This EPS motor is configured to be capable of generating EPS torque Teps in its rotating direction by rotating the rotor by the action of a rotating magnetic field formed in the EPS motor by energizing the stator via the EPS driving device 500. ing.

  On the other hand, a reduction gear (not shown) is fixed to the motor shaft that is the rotation shaft of the EPS motor, and this reduction gear is also meshed with the pinion gear 14. For this reason, the EPS torque Teps generated from the EPS motor functions as an assist torque that assists the rotation of the pinion gear 14 as a kind of steering torque.

  The pinion gear 14 is connected to the lower steering shaft 13 as described above, and the lower steering shaft 13 is connected to the upper steering shaft 12 via the VGRS actuator 200. Accordingly, the driver steering torque MT applied to the upper steering shaft 12 is transmitted to the rack bar 15 in an appropriately assisted manner by the EPS torque Teps, so that the driver's steering burden is reduced.

  The EPS drive device 500 is an electric drive circuit including a PWM circuit, a transistor circuit, an inverter, and the like that are configured to be energized to the stator of the EPS motor. The EPS driving device 500 is electrically connected to a battery (not shown), and is configured to be able to supply a driving voltage to the EPS motor with electric power supplied from the battery. Further, the EPS driving device 500 is electrically connected to the ECU 100, and its operation is controlled by the ECU 100. The EPS driving device 500, together with the EPS actuator 400, constitutes an example of the “steering reaction force suppressing unit” according to the present invention.

  The aspect of the “steering reaction force suppressing means” according to the present invention is not limited to the one exemplified here. For example, the EPS torque Teps output from the EPS motor is reduced by a reduction gear not shown. With this, it may be transmitted directly to the lower steering shaft 13 or may be applied as a force for assisting the reciprocating motion of the rack bar 15.

  On the other hand, the vehicle 10 includes various sensors including a steering torque sensor 16, a steering angle sensor 17, and a rotation angle sensor 18.

  The steering torque sensor 16 is a sensor configured to be able to detect a driver steering torque MT given from the driver via the steering wheel 11. More specifically, the upper steering shaft 12 is divided into an upstream portion and a downstream portion, and has a configuration in which they are connected to each other by a torsion bar (not shown). Rings for detecting a rotational phase difference are fixed to both upstream and downstream ends of the torsion bar. This torsion bar is twisted in the rotational direction in accordance with the steering torque (ie, driver steering torque MT) transmitted through the upstream portion of the upper steering shaft 12 when the driver of the vehicle 10 operates the steering wheel 11. The configuration is such that the steering torque can be transmitted to the downstream portion while causing such a twist. Therefore, when the steering torque is transmitted, a rotational phase difference is generated between the above-described rings for detecting the rotational phase difference. The steering torque sensor 16 is configured to detect the rotational phase difference and to convert the rotational phase difference into a steering torque and output it as an electrical signal corresponding to the steering torque MT. Further, the steering torque sensor 16 is electrically connected to the ECU 100, and the detected steering torque MT is referred to by the ECU 100 at a constant or indefinite period.

  The steering angle sensor 17 is an angle sensor configured to be able to detect a steering angle MA that represents the amount of rotation of the upper steering shaft 12. The steering angle sensor 17 is electrically connected to the ECU 100, and the detected steering angle MA is referred to by the ECU 100 at a constant or indefinite period.

  The rotation sensor 18 is configured to detect a VGRS rotation angle θvg, which is a rotation phase difference between the housing 201 in the VGRS actuator 200 (that is, equivalent to the upper steering shaft 12 in terms of rotation angle) and the lower steering shaft 13. Rotary encoder. The rotation angle sensor 18 is electrically connected to the ECU 100, and the detected VGRS rotation angle θvg is referred to by the ECU 100 at a constant or indefinite period.

  The ECU 100 can calculate the front wheel steering angle δf based on the detected VGRS rotation angle θvg. However, the vehicle 10 may include a rudder angle sensor capable of detecting the front wheel rudder angle δf in the vicinity of the front wheel as the steered wheel.

  The vehicle 10 includes an in-vehicle camera 20 and a vehicle speed sensor 21.

  The in-vehicle camera 20 is an imaging device that is installed on the front nose of the vehicle 10 and configured to image a predetermined area in front of the vehicle 10. The in-vehicle camera 20 is electrically connected to the ECU 100, and the captured front area is sent to the ECU 100 as image data at a constant or indefinite period. The ECU 100 can analyze the image data and acquire various data necessary for LKA control described later.

  The vehicle speed sensor 21 is a sensor configured to be able to detect the vehicle speed V, which is the speed of the vehicle 10. The vehicle speed sensor 21 is electrically connected to the ECU 100, and the detected vehicle speed V is referred to by the ECU 100 at a constant or indefinite period.

  The braking device 600 is an ECB configured to be able to individually supply a braking force to the front wheels FL and FR as steering wheels and the rear wheels RL and RR as non-steering wheels. It is an example of “variable means”. The braking device 600 includes a brake actuator (illustrated brake ACT) 610 and braking members 620FL, 620FR, 620RL, and 620RR corresponding to each wheel.

  The brake actuator 610 supplies an oil passage for supplying hydraulic oil to each of the braking members provided in each wheel, a plurality of solenoid valves installed in the oil passage, and a supply pressure of the hydraulic oil to the oil passage. A braking force control device including an electric oil pump to be controlled.

  The hydraulic pressure supplied to the oil passage is variably controlled according to the open / close state of each solenoid valve and the drive state of the electric oil pump. The brake actuator 610 is electrically connected to the ECU 100, and its operation state is controlled by the ECU 100.

  Each braking member is a hydraulic braking device that is attached to each wheel and applies a frictional force as a braking force to each wheel. As described above, an appropriate hydraulic pressure is supplied to each braking member via the brake actuator 610, and each braking member applies a frictional force corresponding to the supplied hydraulic pressure to each wheel, thereby allowing each wheel to rotate. It is possible to apply a braking force to.

  Here, the magnitude of the braking force relatively corresponds to the magnitude of the driving force. For this reason, when the braking forces applied to the front wheels are different from each other, a front wheel braking / driving force difference Ff is generated at the front wheels, and when the braking forces applied to the rear wheels are different from each other, the rear wheel braking / driving force is applied to the rear wheels. A difference Fr occurs.

<Operation of Embodiment>
Hereinafter, with reference to FIG. 2, the details of the LKA control executed by the ECU 100 will be described as the operation of the present embodiment. FIG. 2 is a flowchart of the LKA control. Note that LKA (Lane Keeping Assist) control is control for causing the vehicle 10 to follow a target travel path (in this embodiment, that is, a lane (lane)), and is one of travel support control executed in the vehicle 10. is there.

  In FIG. 2, the ECU 100 reads various signals including operation signals of various switches provided in the vehicle 10, various flags, sensor signals related to the various sensors, and the like (step S <b> 101), and is installed in the vehicle 10 in advance. It is determined whether or not the LKA mode is selected as a result of the operation button for activating the LKA control being operated by the driver (step S102). When the LKA mode is not selected (step S102: NO), the ECU 100 returns the process to step S101.

  When the LKA mode is selected (step S102: YES), the ECU 100 detects a white line (not necessarily white) that defines the LKA target travel path based on the image data sent from the in-vehicle camera 20. It is determined whether or not it has been performed (step S103).

  If a white line is not detected (step S103: NO), the ECU 100 returns the process to step S101 because a virtual target travel path cannot be set. On the other hand, when the white line is detected (step S103: YES), the ECU 100 calculates various road surface information necessary for causing the vehicle 10 to follow the target travel path (step S104).

  In step S104, the radius R of the target travel path (that is, the reciprocal of the curvature), the lateral deviation Y that is the lateral deviation between the white line and the vehicle 10, and the white line and the vehicle 10 are determined based on a known method. A yaw angle deviation φ is calculated.

  When the various road surface information is calculated, the ECU 100 calculates the target vehicle body slip angle βtg and the target yaw rate γtg as target vehicle state quantities necessary for causing the vehicle 10 to follow the target travel path (step S105). Step S105 is an example of the operation of the “setting unit” according to the present invention.

  These target vehicle state quantities are stored in advance in appropriate storage means such as a ROM in a manner corresponding to the travel road radius R, the lateral deviation Y, and the yaw angle deviation φ. A corresponding value is appropriately selected according to each road surface information calculated in S104.

  However, various modes may be applied regardless of whether the target vehicle body slip angle βtg and the target yaw rate γtg are set.

  When the target vehicle state quantity is calculated, the process branches into two systems. That is, the LKA process defined in steps S106 to S109 and the torque assist process defined in steps S110 to S114.

  First, the LKA process will be described.

  ECU 100 sets a front wheel target rudder angle δftg, which is a target value of front wheel rudder angle δf, based on the target state quantity calculated in step S105 (step S106). When the front wheel target rudder angle δf is set, the ECU 100 drives and controls the VGRS actuator 200 so as to obtain the set front wheel target rudder angle δftg (step S107). Step S107 is an example of the operation of the “movement control means” according to the present invention.

  Further, the ECU 100 sets a front wheel target braking / driving force difference Fftg, which is a target value of the front wheel braking / driving force difference Ff, based on the target state quantity calculated in step S105 (step S108). When the front wheel target braking / driving force difference Fftg is set, the ECU 100 drives and controls the brake actuator 610 so that the set front wheel target braking / driving force difference Fftg is obtained (step S109). Step S109 is another example of the operation of the “movement control means” according to the present invention.

  The setting of the control target value of the VGRS actuator 200 with respect to the front wheel target rudder angle δftg and the setting of the control target value of the brake actuator 610 with respect to the front wheel target braking / driving force difference Fftg are made by referring to the control maps stored in the ROM. Done.

  When step S109 is executed, the process returns to step S101. The LKA process is performed in this way.

  The setting of the front wheel target rudder angle δftg in step S106 and the setting of the front wheel target braking / driving force difference Fftg in step S108 will be described later.

  On the other hand, in the torque assist process, first, an EPS basic target torque Tepsbs, which is a reference value of the EPS torque Teps to be supplied from the EPS actuator 400, is calculated (step S110).

  This EPS basic target torque Tepsbs is a torque that compensates for the torque shortage caused by the physique of the VGRS motor 202. More specifically, the size of the VGRS motor 202 is determined on the assumption that the EPS actuator 400 performs corresponding torque compensation. Therefore, when no torque assist is obtained from the EPS actuator 400, the VGRS motor 202 cannot steer the front wheels against the inertia of the mechanical steering transmission path from the lower steering shaft 14 to the steered wheels. Therefore, torque assist from the EPS actuator 400 is always executed during the period in which the LKA process by the VGRS actuator 200 is executed.

  Next, the ECU 100 estimates a steering reaction force torque T (that is, an example of the “steering reaction force” according to the present invention) (step S111). That is, step S111 is an example of the operation of the “estimating means” according to the present invention. The estimation of the steering reaction force torque T will be described later together with the setting modes of the front wheel target steering angle δftg and the front wheel target braking / driving force difference Fftg described above.

  When the steering reaction force torque is estimated, the ECU 100 calculates a steering reaction force suppression torque Tct for suppressing the estimated steering reaction force torque T (step S112). The steering reaction force suppression torque Tct is a torque obtained by reversing the steering reaction force torque T and the sign of positive and negative.

  When the steering reaction force suppression torque Tct is calculated, the ECU 100 adds the steering reaction force suppression torque Tct to the EPS basic target torque Tepsbs calculated in step S110, thereby finally outputting the EPS reaction force suppression torque Tct. EPS target torque Tepstg, which is a large torque, is calculated (step S113).

  When the EPS target torque Tepstg is calculated, the ECU 100 drives and controls the EPS actuator 400 so that the calculated EPS target torque Tepstg is obtained (step S114). That is, step S114 is an example of the operation of the “steering reaction force control means” according to the present invention. When step S114 is executed, the process returns to step S101. The torque assist process is executed in this way.

  Thus, according to the present embodiment, the VGRS actuator 200 serving as the steering angle varying means and the braking device 600 serving as the braking / driving force varying means are cooperatively controlled, and the front wheel steering angle δf and the front wheel braking / driving force difference Ff are used as parameters. By doing so, the vehicle body slip angle β and the yaw rate γ, which are the state quantities of the vehicle 10, can be controlled independently of each other. As a result, the state quantity of the vehicle 10 can be maintained at the target state quantity, and a suitable lane keeping running can be realized.

  Here, in particular, since the steering reaction force torque T is estimated in step S111, and the estimated steering reaction force torque is reflected in the EPS torque Teps, which is the final output torque of the EPS actuator 600, the steering wheel 11 is steered. The reaction force is not applied, and the steering wheel 11 is prevented from being reversely steered in the direction opposite to the original turning direction in the LKA process. For this reason, the driver does not need to hold the steering wheel 11 and can maintain the target lane by letting go.

  In other words, if the steering reaction torque T (a value correlated with the steering reaction force) is not estimated in step S111, the driver holds the steering wheel 11 and gives a steering torque that antagonizes the steering reaction force. Unless it is, the state quantity of the vehicle 10 cannot be maintained at the target state quantity.

This is because although the above-mentioned basic target torque Tepsbs is supplied from the EPS actuator 600, the steering wheel 11 which is not steered has a lighter steering load than the steering system including the steering wheel and the steering mechanism 19. As is obvious, when the steering wheel 11 is not held, the torque supplied from the VGRS motor 202 that merely rotates the upper steering shaft 12 and the lower steering shaft 13 is consumed to reverse-steer the steering wheel 11. It will be done.
<Details of steering reaction force estimation>
As described above, the ECU 100 according to the present embodiment estimates the steering reaction torque T generated by the LKA process in step S111 in the LKA control. The estimation of the steering reaction force torque T is executed based on a motion equation relating to the state quantity of the vehicle 10 (hereinafter simply referred to as “vehicle motion equation”) constructed in advance. The equation of motion of the vehicle 10 is defined as, for example, the following equation (1).

ここで、（１）式における係数Ａ１１、Ａ１２、Ａ１３、Ａ２１、Ａ２２、Ａ２３、Ａ３１、Ａ３２及びＡ３３は、夫々、下記（２）乃至（１０）式の如くに規定される。

Here, the coefficients A11, A12, A13, A21, A22, A23, A31, A32, and A33 in the equation (1) are respectively defined as the following equations (2) to (10).

ここで、上記各式における各参照記号の表す意味は以下の通りである。

Here, the meanings of the reference symbols in the above formulas are as follows.

β: Body slip angle γ: Yaw rate T: Torque generated in the steered wheels (ie, torque corresponding to the steering reaction force)
St ... Stability factor M ... Vehicle weight V ... Vehicle speed lf ... Vehicle center of gravity-front axle distance lr ... Vehicle center of gravity-rear axle distance l ... lf + lr (= wheel base)
df ... front tread width dr ... rear tread width Kf ... front wheel cornering power Kr ... rear wheel cornering power K ... steering wheel kingpin offset t ... wheel trail amount δf ... front wheel steering Angle Ff: Front wheel braking / driving force difference (front-rear force difference between left and right wheels)
Fr: Rear wheel braking / driving force difference (front-rear force difference between left and right wheels)
Here, as already described, in the LKA processing according to the present embodiment, the vehicle body slip angle β and the yaw rate γ as the state quantities of the vehicle 10 are independently controlled by the front wheel steering angle δf and the front wheel braking / driving force difference Ff. It is possible. The reason why such independent control is possible will be apparent from the above equation of motion. That is, if there are two types of control targets, the vehicle body slip angle β and the yaw rate γ, these can be independently controlled by two types of control parameters.

  In step S106 of the LKA control described above, the front wheel target rudder angle δftg is obtained by setting β and γ in the above equation of motion to βtg and γtg calculated in step S105, respectively. However, in this embodiment, the relative relationship between the two derived from the equation of motion is previously mapped, and the ECU 100 can uniquely set the front wheel target rudder angle δftg with respect to the targets β and γ.

  Similarly, in step S108 of the LKA control described above, the front wheel target braking / driving force difference Fftg is obtained by setting β and γ in the above equation of motion to βtg and γtg calculated in step S105, respectively. However, in the present embodiment, the relative relationship between the two derived from the equation of motion is mapped in advance, and the ECU 100 can uniquely set the front wheel target braking / driving force difference Fftg with respect to the targets β and γ. it can.

  On the other hand, when the steering reaction torque T is applied as a control target, another control parameter is required. In the above equation of motion, the rear wheel braking / driving force difference Fr corresponds to this. By adding the control parameter, it can be seen that the steering reaction torque T is expressed as in the following equation (11) or (12).

式（１１）は、操舵反力トルクＴを算出するためのパラメータとして前輪舵角δｆ及び前輪制駆動力差Ｆｆが採用された場合であり、式（１２）は、同パラメータとして前輪舵角δｆ及び後輪制駆動力差Ｆｒが採用された場合に対応する。いずれにせよ、操舵反力トルクＴは、車両１０の状態量制御に使用されるパラメータ（前輪舵角δｆ及び前輪制駆動力差Ｆｆ又は後輪制駆動力差Ｆｆ）を、本発明に係る「複数要素」の一例とすることによって正確に推定される。

Expression (11) is a case where the front wheel steering angle δf and the front wheel braking / driving force difference Ff are adopted as parameters for calculating the steering reaction torque T, and Expression (12) is the front wheel steering angle δf as the same parameter. This corresponds to the case where the rear wheel braking / driving force difference Fr is adopted. In any case, the steering reaction force torque T is a parameter (front wheel steering angle δf and front wheel braking / driving force difference Ff or rear wheel braking / driving force difference Ff) used for controlling the state quantity of the vehicle 10 according to the present invention. It is accurately estimated by taking an example of “multiple elements”.

  Here, the equation of motion is an equation when the front wheel steering angle δf, the front wheel braking / driving force difference Ff and the rear wheel braking / driving force difference Fr are used as parameters, but the parameters are not limited to these, For example, any one of the above parameters may be replaced with the rear wheel steering angle δr (in this case, the coefficient changes, but there is no conceptual change). In this case, the vehicle 10 preferably includes a rear wheel steering angle varying device such as an ARS that enables the steering angle control of the rear wheels.

  On the other hand, the steering reaction torque T can be obtained by using target state quantities (that is, a vehicle body slip angle β and a yaw rate γ) instead of the parameters described above as another example of the “plural elements” according to the present invention. It can be estimated. That is, when the above equation of motion is modified, the steering reaction torque T is expressed as the following equation (13) as a function of β and γ.

ここで、（１３）式における係数Ｃ１及び係数Ｃ２は、夫々下記（１４）式及び（１５）式の如くに表される。尚、Ｍｒは、リア車軸重量（Ｍｒ＝ｌｆＭ／Ｉ）である。

Here, the coefficient C1 and the coefficient C2 in the expression (13) are expressed as the following expressions (14) and (15), respectively. Note that Mr is the rear axle weight (Mr = lfM / I).

このように、車体スリップ角β及びヨーレートγに基づいて操舵反力トルクＴを推定する場合、操舵反力トルクＴは、上述のＬＫＡ制御で言えばステップＳ１０５の段階で推定準備が整うことになる。従って、このような目標状態量に応じた操舵反力トルクＴの推定は、即時性に優れる。

As described above, when the steering reaction torque T is estimated based on the vehicle body slip angle β and the yaw rate γ, the steering reaction torque T is ready for estimation in the above-described LKA control in the step S105. . Therefore, the estimation of the steering reaction torque T according to the target state quantity is excellent in immediacy.

  On the other hand, the estimation based on the target state quantity does not necessarily accurately reflect the actual response of the vehicle 10. For example, since the VGRS actuator 200 and the brake actuator 610 have response delays at various parts, the estimated steering reaction torque T is transiently coincident with the actual steering reaction torque even if the convergence value is correct. May not.

  From such a viewpoint, estimation based on the above-described control parameters is effective. Since the estimation based on the control parameter always reflects the control parameter at that time (that is, the front wheel steering angle δf, the front wheel braking / driving force difference Ff or the rear wheel braking / driving force difference Fr), the target state is not accurate. Better than quantity-based estimation.

  In any case, however, according to the present embodiment, the steering reaction torque T is estimated at an early stage where the reverse steering of the steering wheel 11 is not actually caused. Therefore, it is possible to cancel the steering reaction torque T in a feed-forward manner and perform good state quantity control.

  Note that the vehicle 10 according to the present embodiment includes the braking device 600 as an example of the “braking / driving force varying means” according to the present invention, but the braking device 600 uses the vehicle behavior on the deceleration side as a control range. Speaking from the viewpoint of expanding the control range, the vehicle 10 includes driving force distribution means such as a driving force distribution differential (that is, a kind of LSD (Limited Slip Differential)). May be. In this case, since both the driving force and the braking force can be individually controlled, the vehicle behavior can be controlled on both the acceleration side and the deceleration side. Alternatively, instead of controlling the braking force independently for each wheel, a configuration in which only the driving force can be controlled independently for each wheel by this type of driving force distribution means may be adopted.

  The present invention is not limited to the above-described embodiments, and can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification. Is also included in the technical scope of the present invention.

  The present invention can be used for, for example, a vehicle having a function of causing the vehicle to follow a target travel path.

  FL, FR, RL, RR ... wheels, 10 ... vehicle, 11 ... steering wheel, 12 ... upper steering shaft, 13 ... lower steering shaft, 14 ... pinion gear, 16 ... steering angle sensor, 17 ... steering torque sensor, 18 ... Rotation angle sensor, 100 ... ECU, 200 ... VGRS actuator, 300 ... VGRS driving device, 400 ... EPS actuator, 500 ... EPS driving device, 600 ... braking device, 610 ... brake actuator.

Claims (4)

A rudder angle varying means capable of changing the rudder angle of at least one of the front wheels and the rear wheels independently of a driver operation for urging the change of the at least one rudder angle;
An apparatus for controlling a vehicle comprising: braking / driving force varying means capable of changing a braking / driving force difference between left and right wheels in at least one of a front wheel and a rear wheel,
Setting means for setting a plurality of target state quantities corresponding to the target motion state of the vehicle;
Motion control means for controlling the rudder angle varying means and the braking / driving force varying means in accordance with the set plurality of target state quantities so that the motion state of the vehicle becomes the target motion state;
Each of the plurality of set target state quantities, the at least one rudder angle according to the set plurality of target state quantities and the left and right wheels at the at least one according to the set plurality of target state quantities Estimating means for estimating a steering reaction force transmitted from a steered wheel to a steering device in a process in which the motion state of the vehicle converges to the target motion state based on a plurality of elements in the braking / driving force difference. A control device for a vehicle. The target state quantity is a yaw rate and a vehicle body slip angle of the vehicle,
The vehicle control device according to claim 1, wherein the estimation unit estimates the steering reaction force based on the yaw rate and a vehicle body slip angle as the plurality of elements. The said estimation means estimates the said steering reaction force based on said at least one steering angle and the braking / driving force difference of the left and right wheels in said at least one as said plurality of elements. Vehicle control device. The vehicle includes a steering reaction force suppressing unit capable of suppressing the steering reaction force,
The vehicle control device comprises:
The vehicle according to any one of claims 1 to 3, further comprising a steering reaction force suppression unit that controls the steering reaction force suppression unit so that the estimated steering reaction force is suppressed. Control device.

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