Steering device of vehicle

Abstract

To reduce burdens / loads on a driver by suppressing effects of unevenness on a road surface thereby improving straight-running stability.SOLUTION: A steering device of a vehicle is provided with a pair of road surface reaction force detecting parts that detect reaction force on a road surface that is received by tires mounted on left and right steering wheels, a toe adjustment actuator connected to either of the left and right steering wheels, and a control part that controls driving force of the toe adjustment actuator. The control part is provided with: left / right toe-variation setting parts that respectively set toe variations of the tires mounted on the left and right steering wheels, on the basis of the respective reaction force on the road surface received by the left and right tires detected by the road surface reaction force detecting part; a differential calculating part that calculates a differential between the toe variations; an actuation-amount calculating part that calculates actuator actuation amounts offsetting the differential; and a driving part that drives the toe adjustment actuator at the actuator actuation amounts.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a steering device for a vehicle. [Background technology]

[0002] When driving, tires are subjected to forces of various magnitudes and in various directions (front-back, left-right, up-down). These forces are transmitted from the tires through the suspension and bushes to the body. Basically, the geometry, suspension structural components, and bushing rigidity are set to hold the tires in the position desired as much as possible by the design, thereby regulating the tire orientation. However, since the tires are affected by unevenness in the road surface while driving, the amount of displacement cannot always be kept at zero.

[0003] As a result, even if the driver holds the steering wheel in a straight-ahead position (neutral position), the direction of the tires can be unexpectedly displaced in the toe-in or toe-out direction due to the forces acting on the tires in the front-back, left-right, and up-down directions, causing the vehicle to try to turn against the driver's will. This causes the steering wheel to wobble and reduces straight-ahead stability.

[0004] For example, the change in the tire will be described with reference to the steering mechanism 101 shown in Figures 11 and 12. When one of the tires Fl, Fr (the right tire Fr in the figure) mounted on the left and right front wheels that are steered wheels attempts to go over a convex surface of the road surface, if reaction forces in the left and right directions are ignored, a reaction force Fu in the pushing up direction and a reaction force Fb trying to push it back backward act on the tire Fr. This causes the toe of the right tire Fr to be displaced, as shown by the dashed line in Figure 11, and the vehicle attempts to turn in a direction unintended by the driver.

[0005] The driver, sensing the unexpected movement of the vehicle, operates the steering wheel, and the driver tries to return the tires Fl and Fr to the straight-ahead direction via the steering gear box 102. In this way, the driver, sensing the unexpected movement of the vehicle, must operate the steering wheel to make the vehicle travel straight, which increases the burden on the driver.

[0006] As a countermeasure against this, for example, Patent Document 1 (JP Patent Publication 2006-56374A) discloses a technique in which auxiliary rack bar mechanisms are provided on rack bars extending to the left and right from a steering gear box, and axial force sensors are provided on the left and right auxiliary rack bar mechanisms. In the technique disclosed in this document, while the vehicle is traveling straight, the difference between the axial forces generated in the left and right tie rods detected by each axial force sensor is obtained. If this difference is equal to or greater than a predetermined threshold value, the motor of the auxiliary rack bar mechanism provided on the side with the larger axial force is driven. As a result, the steered wheels are turned in a direction that reduces the force acting on the steered wheels, thereby reducing the burden on the driver. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2006-56374 A Summary of the Invention [Problem to be solved by the invention]

[0008] In the technology disclosed in the above-mentioned document, the displacement of the steered wheels is detected from the axial force detected by the axial force sensor provided on the left and right auxiliary rack bar mechanisms, and the motor of the auxiliary rack bar mechanism is driven to turn the wheels in a direction that offsets the detected displacement.

[0009] However, when the vehicle is running, loads are generated on the tires in the vertical, horizontal, and front-rear directions, which causes the toe to change. The above-mentioned axial force sensor can only measure the pushing and pulling force of the tie rod, and cannot detect the change in the toe. As a result, there is a limit to how much the sensor can suppress the effect of road unevenness and improve the straight-line stability of the vehicle.

[0010] The present invention aims to provide a vehicle steering device that can suppress the effects of toe changes that occur when tires pass over an uneven road surface, thereby improving straight-line stability and reducing the burden on the driver. [Means for solving the problem]

[0011] The present invention is a steering device for a vehicle that applies a driving force to a steered wheel that offsets a toe change caused by an uneven road surface, and includes a pair of road reaction force detection units that detect a road reaction force received by tires attached to the left and right steered wheels, a toe adjustment actuator connected to one of the left and right steered wheels, and a control unit that controls the driving force of the toe adjustment actuator, and the control unit includes a left and right toe change amount setting unit that sets the toe change amount of the tires attached to the left and right steered wheels based on the individual road reaction forces received by the left and right tires detected by each road reaction force detection unit, a difference calculation unit that calculates the difference between the toe change amounts set by the left and right toe change amount setting units, an operation amount calculation unit that calculates an actuator operation amount that offsets the difference determined by the difference calculation unit, and a drive unit that drives the toe adjustment actuator with the actuator operation amount calculated by the operation amount calculation unit. Effect of the Invention

[0012] According to the present invention, the amount of toe change of the tires attached to the left and right steered wheels is set based on the road reaction force received by the tires, and a toe adjustment actuator connected to one of the steered wheels is driven with an actuator operation amount that offsets the difference between the amounts of toe change. This suppresses the effects of toe change that occurs in the left and right steered wheels when the tires travel over an uneven road surface, improving straight-line stability and reducing the burden on the driver.

[0013] Furthermore, since a single toe adjustment actuator is used to offset the toe change amounts of the tires attached to the left and right steered wheels, the number of parts is reduced, leading to cost reduction. [Brief description of the drawings]

[0014] [Figure 1A] FIG. 1 is a schematic plan view of a main part of a steering device according to a first embodiment, showing a state in which a toe change in a toe-out direction of a right steered wheel is adjusted; [Figure 1B]FIG. 2 is a schematic plan view of the main part of the steering device showing a state in which the toe change in the toe-out direction of the left steering wheel is offset by the right steering wheel. [Diagram 2] The right side view of FIG. 1A [Diagram 3] Schematic diagram of the steering control unit [Figure 4] A flowchart showing a routine for calculating the amount of toe adjustment actuator operation. [Diagram 5] Conceptual diagram of tire input load-tire toe change map [Figure 6] Conceptual diagram of the suspension stroke-tire toe change table [Figure 7] Timing chart showing tire toe change in response to road surface irregularities [Figure 8] Timing chart showing tire toe change with respect to suspension stroke [Figure 9A] Timing chart showing the total toe change of the left tire [Figure 9B] The timing chart showing the total toe change of the right tire [Figure 9C] FIG. 1 is a timing chart showing the difference between the total toe change amount of the left tire and the reference total toe change amount of the left tire, and the operation amount of the toe adjustment actuator. [Figure 10] Schematic configuration diagram of a steering control unit according to a second embodiment. [Figure 11] Schematic plan view of a main part of a conventional steering device [Figure 12] Right side view of Figure 11 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. [First embodiment] A first embodiment of the present invention is shown in Figures 1 to 9C. Reference numeral 1 in Figures 1A and 1B denotes a steering device. This steering device 1 is provided with a steering gear box 2. A rack-and-pinion steering gear mechanism is formed in this steering gear box 2. This steering gear mechanism has a rack shaft 2a. This rack shaft 2a is supported in the steering gear box 2 so as to be able to slide back and forth in the axial direction. A rack (not shown) is formed on this rack shaft 2a. A pinion formed on a pinion shaft is meshed with this rack.

[0016] Although not shown, an end of a steering shaft is connected to the pinion shaft. A steering handle (hereinafter simply referred to as the "handle") is fixed to the base end of the steering shaft. The driver can change the traveling direction of the vehicle by operating this handle.

[0017] Furthermore, one end of tie rods 3l, 3r is connected to both the left and right ends of the rack shaft 2a. The other end of the left tie rod 3l is connected to a tie rod end 4l. Meanwhile, the other end of the right tie rod 3r is connected to one end of the tie rod end 4r via a toe adjustment actuator 5. This toe adjustment actuator 5 adjusts the distance between the tie rod 3r and the tie rod end 4r to vary the toe angle of the right front wheel Fr regardless of steering by the steering wheel.

[0018] Furthermore, the other ends of the left and right tie rod ends 4l, 4r are connected to knuckle arms 6l, 6r extending from left and right steering knuckles (not shown). These steering knuckles are supported on a vehicle body frame (not shown) via front arms 7l, 7r so as to be freely steerable. Furthermore, the steering knuckles rotatably support tires Fl, Fr mounted on the left and right steered wheels (left and right front wheels). A hub bearing is housed in the steering knuckle. A hub is supported by this hub bearing so as to be freely rotatable around the axle.

[0019] As shown in Fig. 2, a tire wheel is fixed to the hub 9r (9l). Tires Fl, Fr are mounted on the outer periphery of the tire wheel. A tire load sensor 12r (12l) is also provided on the hub 9r (9l). The tire load sensor 12r (12l) measures the loads (road reaction forces) received by the tires Fl, Fr in the front-rear and lateral directions.

[0020] Furthermore, a suspension stroke sensor 13r (13l) is fixed to the front suspension 8r (8l). This suspension stroke sensor 13r (13l) detects the stroke amount (suspension stroke amount) Xr (Xl) of the front suspension 8r (8l). The tire load sensors 12r, 12l and the suspension stroke sensors 13r, 13l correspond to the road surface reaction force detection unit of the present invention.

[0021] The above-mentioned toe adjustment actuator 5 is operated in accordance with a drive signal transmitted from a steering control unit (steering_ECU) 11 serving as a control section.

[0022] The steering_ECU 11 is composed of a microcontroller including a CPU, RAM, ROM, a rewritable non-volatile memory (flash memory or EEPROM), and peripheral devices. The ROM stores programs and fixed data required for the CPU to execute various processes. The RAM is provided as a work area for the CPU, and temporarily stores various data for the CPU. The CPU is also called an MPU (Microprocessor) or a processor. Instead of the CPU, a GPU (Graphics Processing Unit) or a GSP (Graph Streaming Processor) may be used. Alternatively, a selective combination of the CPU, GPU, and GSP may be used.

[0023] 3, a toe adjustment amount calculation unit 11a is provided in the steering_ECU 11. The toe adjustment amount calculation unit 11a drives the toe adjustment actuator 5 to realize driving stability.

[0024] The left and right tire load sensors 12l, 12r and the left and right suspension stroke sensors 13l, 13r are connected to the input side of the toe adjustment amount calculation unit 11a. Also, the toe adjustment actuator 5 is connected to the output side of the toe adjustment amount calculation unit 11a.

[0025] The toe adjustment amount calculation unit 11a calculates the amount of toe change, which changes depending on the reaction force from the road surface received by the left and right tires Fl and Fr when passing over an uneven road surface.

[0026] The toe adjustment amount calculation unit 11a calculates the toe change amount by first detecting the lateral loads Ply, Pry and the front-rear loads Plx, Prx received by the left and right tires Fl, Fr using the left and right tire load sensors 12l, 12r. The toe adjustment amount calculation unit 11a also detects the suspension stroke amounts Xl, Xr using the left and right suspension stroke sensors 13l, 13r.

[0027] The toe adjustment amount calculation unit 11a then calculates the toe change amounts of the left and right tires Fl, Fr based on the lateral loads Ply, Pry, the front-rear loads Plx, Prx, and the vertical loads Plz, Prz.

[0028] Next, the toe adjustment amount calculation unit 11a calculates the difference between the toe change amount of the right tire Fr and the toe change amount of the left tire Fl as a reference.Then, the toe adjustment amount calculation unit 11a calculates the actuator operation amount according to this difference.The toe adjustment amount calculation unit 11a operates the toe adjustment actuator 5 with this actuator operation amount.

[0029] The calculation of the operation amount of the toe adjustment actuator 5 executed by the toe adjustment amount calculation unit 11a is specifically processed according to a toe adjustment actuator operation amount calculation routine shown in FIG.

[0030] The toe adjustment amount calculation unit 11a first reads the loads (tire input loads) input to the left and right tires Fl, Fr (step S1). The input loads are the lateral loads Ply, Pry and the front-rear loads Plx, Prx received by the left and right tires Fl, Fr from the road surface. The lateral loads Ply, Pry and the front-rear loads Plx, Prx are detected by the left and right tire load sensors 12l, 12r.

[0031] The toe adjustment amount calculation unit 11a also reads the left and right suspension stroke amounts Xl and Xr (step S2). The left and right suspension stroke amounts Xl and Xr are detected by the left and right suspension stroke sensors 13l and 13r.

[0032] Next, the toe adjustment amount calculation unit 11a sets the tire toe change amount (step S3). This tire toe change amount is set by referring to the tire input load-tire toe change amount map with interpolation calculation. The parameters required when referring to the tire input load-tire toe change amount map are the tire input loads, that is, the lateral loads Ply, Pry and the front-rear loads Plx, Prx.

[0033] FIG. 5 shows a conceptual diagram of the tire input load-tire toe change map. The tire toe change when lateral loads Ply, Pry and longitudinal loads Plx, Prx are applied to the left and right tires Fl, Fr can be mechanically calculated. If the characteristics of the vehicle are known, the tire toe change caused by the lateral loads Ply, Pry and longitudinal loads Plx, Prx can be obtained in advance from these characteristics by simulation or the like. If this is made into a map, the tire input load-tire toe change map can be easily constructed.

[0034] For example, when a tire Fl (Fr) of a vehicle traveling straight ahead attempts to go over a convex surface, a load due to a reaction force from the road surface is applied to the tires Fl and Fr as shown in Fig. 2. This load has three directional components: a load Prx (Plx) that presses the tire Fl (Fr) backward, a vertical load Prz (Plz) that presses it upward, and a load Pry (Ply) that presses it laterally (not shown).

[0035] Among these three-directional components, the tire load sensors 12l, 12r detect the components of the longitudinal loads Plx, Prx and the lateral loads Ply, Pry. As a result, as shown in Fig. 7, the toe adjustment amount calculation unit 11a detects the amount of change in the tire longitudinal load and the tire lateral load. For convenience, it is assumed in Fig. 7 that the lateral loads Ply, Pry are not occurring. If it is assumed that the lateral loads Ply, Pry are not occurring, the tire toe change amount is set to a value that traces the longitudinal loads Plx, Prx.

[0036] Next, the toe adjustment amount calculation unit 11a sets the tire toe change amount based on the left and right suspension stroke amounts (step S4). This tire toe change amount is set by referring to a suspension stroke amount-tire toe change amount table based on the suspension stroke amounts Xl and Xr. A conceptual diagram of the suspension stroke amount-tire toe change amount table is shown in FIG. 6. As shown in the figure, the suspension stroke amounts Xl and Xr are set in the direction of expansion and contraction from a stationary state. The suspension stroke amounts Xl and Xr have a characteristic that as the change amount increases in either compression or expansion, the tire toe change amount also increases proportionally. Therefore, the suspension stroke amounts Xl and Xr and the tire toe change amount can also be calculated from a linear equation with a certain slope determined by the characteristics of the vehicle.

[0037] For example, as shown in Fig. 2, when the tire Fr (Fl) of a vehicle traveling straight ahead attempts to go over a convex surface, a vertical load Prz (Plz) is generated on the tire Fr (Fl) by a reaction force from the road surface, which pushes the tire Fr (Fl) upward. Then, the suspension stroke amount Xr (Xl) is detected by the suspension stroke sensor 13r (13l) as shown in Fig. 8. Then, by referring to a table based on this suspension stroke amount Xr (Xl), a tire toe change amount that traces the suspension stroke amount Xr (Xl) is set.

[0038] Next, the toe adjustment amount calculation unit 11a calculates the total toe change amount of the left and right tires Fl, Fr (step S5). The process in step S5 corresponds to the left and right toe change amount setting unit of the present invention.

[0039] FIG. 9A illustrates an example of the total toe change amount of the left tire Fl. FIG. 9B illustrates an example of the total toe change amount of the right tire Fr. As shown in FIG. 9A and FIG. 9B, the left and right total toe change amount is calculated by adding the tire toe change amount based on the tire input load set in step S3 and the tire toe change amount based on the suspension stroke amount set in step S4. In the figure, the toe-in direction is indicated by plus (+) and the toe-out direction is indicated by minus (-). Therefore, the toe angles of the left and right tires Fl.Fr move symmetrically in plus (+) and minus (-). The processing in steps S3 to S5 corresponds to the toe change amount setting unit of the present invention.

[0040] Thereafter, the toe adjustment amount calculation unit 11a calculates the difference between the left total toe change amount and the left total toe change amount as a reference (step S6). The process in step S6 corresponds to the difference calculation unit of the present invention.

[0041] As shown in Figure 9C, this difference is Difference = Right tire total toe change amount - Left tire total toe change amount In the figure, the toe-in direction is indicated with a plus (+) and the toe-out direction is indicated with a minus (-).

[0042] If this difference is added to the total toe change amount of the right tire, the total toe change amount of the right tire Fr will show a symmetrical change with respect to the total toe change amount of the left tire Fl. In other words, the toe angle of the right tire Fr can be made to always match the toe angle of the left tire Fl.

[0043] Then, the toe adjustment amount calculation unit 11a calculates the toe adjustment actuator operation amount corresponding to the difference (step S7). Note that the process in step S7 corresponds to the operation amount calculation unit of the present invention.

[0044] Next, the toe adjustment amount calculation unit 11a outputs a drive signal corresponding to the toe adjustment actuator operation amount to the toe adjustment actuator 5 (step S8), and exits the routine. Note that the process in step S8 corresponds to the drive unit of the present invention.

[0045] 9C, the toe adjustment actuator 5 expands and contracts the tie rod end 4r with a drive signal according to the amount of operation calculated by the toe adjustment amount calculation unit 11a. This changes the toe angle of the drive wheel on which the right tire Fr is mounted, and the toe angle of the right tire Fr is adjusted to the same toe angle as that of the left tire Fl.

[0046] For example, in Fig. 1A, the right tire Fr shows an unintended change in the toe-out direction when passing over an uneven road surface. In contrast, the left tire Fl does not show a large toe change. In this embodiment, the toe angle of the right tire Fr is adjusted to match the toe angle of the left tire Fl. Therefore, in the state shown in Fig. 1A, the toe angle of the right tire Fr is adjusted by the operation of the toe adjustment actuator 5 as shown by the dashed line.

[0047] On the other hand, for example, Fig. 1B shows a state in which the left tire Fl makes an unintended change in the toe-out direction when passing over an uneven road surface. In contrast, it is assumed that the left tire Fl does not make a large toe change as shown by the solid line. In this embodiment, the toe angle of the right tire Fr is adjusted to match the toe angle of the left tire Fl.

[0048] 1B, the toe angle of the right tire Fr is corrected to the same toe angle as the left tire Fl, as shown by the dashed line, by the operation of the toe adjustment actuator 5. This improves the straight-line stability of the vehicle.

[0049] In this manner, in this embodiment, instead of providing a toe adjustment actuator 5 on each of the left and right tires Fl, Fr, a single toe adjustment actuator 5 is used to adjust the toe change amount of the left and right tires Fl, F. This reduces the number of parts and enables costs to be reduced.

[0050] In this embodiment, the toe change amount of tires Fl, Fr mounted on the left and right steered wheels is set based on the road surface reaction force received by the tires Fl, Fr. Then, the toe adjustment actuator 5 connected to one of the steered wheels is driven by an actuator operation amount that offsets the difference between the two toe change amounts. As a result, the effect of the toe change that occurs when the left and right tires Fl, Fr mounted on the steered wheels pass over an uneven road surface is suppressed, straight-line stability is improved, and the burden on the driver who operates the steering wheel is reduced.

[0051] Furthermore, the difference in the total toe change amount that occurs between the left and right tires Fl and Fr when passing over an uneven road surface is offset, so that the uneven road surface is less likely to have an effect on steering. This results in good cornering performance. [Second embodiment] A second embodiment of the present invention is shown in Fig. 10. In the first embodiment described above, the total toe change amount is calculated based on the tire input loads (lateral loads Ply, Pry and front-rear loads Plx, Prx) detected by the left and right tire load sensors 12l, 12r and the suspension stroke amounts Xl, Xr detected by the suspension stroke sensors 13l, 13r.

[0052] In contrast, in this embodiment, road surface irregularities ahead of the vehicle are detected based on road surface recognition information acquired while the vehicle is traveling.The tire input load and suspension stroke amount are estimated based on the detected road surface irregularities.The estimated tire input load and suspension stroke amount are corrected by the tire input loads detected by the tire load sensors 12l and 12r and the suspension stroke amounts Xl and Xr detected by the suspension stroke sensors 13l and 13r, respectively.

[0053] Then, the corrected tire input load and suspension stroke amount are read in steps S1 and S2, respectively, of the toe adjustment actuator operation amount calculation routine shown in FIG.

[0054] That is, as shown in FIG. 10, the steering_ECU 11 is provided with a tire input load estimation calculation unit 11b, a tire input load correction value calculation unit 11c, a first correction unit 11d, a suspension stroke amount estimation calculation unit 11e, a suspension stroke amount correction value calculation unit 11f, and a second correction unit 11g on the input side of a toe adjustment amount calculation unit 11a.

[0055] The tire input load estimation calculation unit 11b calculates the amount of road surface unevenness (height, depression) based on the forward road surface recognition information. The tire input load estimation calculation unit 11b also obtains estimated tire input loads (lateral loads Ply, Pry and front-rear loads Plx, Prx) which are estimated road surface reaction forces that the tires Fl, Fr receive when passing over the uneven road surface.

[0056] Furthermore, the tire input load estimation calculation unit 11b predicts the time when the vehicle will reach the road surface unevenness based on the distance to the road surface unevenness and the vehicle speed. Then, when the road surface arrival time is reached, the tire input load estimation calculation unit 11b outputs the estimated tire input load to the first correction unit 11d.

[0057] The above-mentioned forward road surface recognition information is acquired from forward driving environment information recognized by a forward driving environment information acquisition unit. Examples of the forward driving environment information acquisition unit include a stereo camera, a millimeter wave radar, a microwave radar, a LiDAR (Light Detection and Ranging), etc. Alternatively, a monocular camera and each radar may be combined to form the forward driving environment information acquisition unit.

[0058] Moreover, the tire input load correction value calculation unit 11c outputs the tire input loads (lateral loads Ply, Pry and front-rear loads Plx, Prx) detected by the tire load sensors 12l, 12r as correction values ​​to a first correction unit 11d.

[0059] The first correction unit 11d adds the correction value calculated by the tire input load correction value calculation unit 11c to the tire input load (lateral loads Ply, Pry and front-rear loads Plx, Prx) estimated by the tire input load estimation calculation unit 11b. The first correction unit 11d sets the added value as a new tire input load and outputs it to the toe adjustment amount calculation unit 11a.

[0060] As a result, the tire input load estimated by the tire input load estimation calculation unit 11b becomes the feedforward control value. Also, the correction value calculated by the tire input load correction value calculation unit 11c becomes the feedback correction value. There is a slight time lag between the feedforward control value and the feedback correction value. However, since the tire input load is feedforward controlled, the feedback control value becomes a relatively small value, and high responsiveness can be obtained.

[0061] On the other hand, the suspension stroke amount estimation calculation unit 11e calculates the road surface unevenness amount based on the above-mentioned forward road surface recognition information. An estimated stroke amount (estimated suspension stroke amount) is obtained based on this road surface unevenness amount. This estimated stroke amount is an estimated road surface reaction force received by the tires Fl, Fr and transmitted to the front suspensions 8l, 8r when passing over an uneven road surface.

[0062] Furthermore, the suspension stroke amount estimation calculation unit 11e predicts the time when the vehicle will reach the road surface unevenness. The time when the vehicle will reach the road surface unevenness is predicted based on the distance to the road surface unevenness and the vehicle speed. Then, when the road surface arrival time is reached, the suspension stroke amount estimation calculation unit 11e outputs the estimated suspension stroke amount to the second correction unit 11g.

[0063] Also, the suspension stroke amount correction value calculation section 11f outputs the suspension stroke amounts Xl, Xr detected by the suspension stroke sensors 13l, 13r as correction values ​​to a second correction section 11g.

[0064] The second correction unit 11g calculates a new suspension stroke amount by adding the correction value calculated by the suspension stroke amount correction value calculation unit 11f to the suspension stroke amount estimated by the suspension stroke amount estimation calculation unit 11e. The second correction unit 11g then outputs the new suspension stroke amount to the toe adjustment amount calculation unit 11a.

[0065] As a result, the suspension stroke amount estimated by the suspension stroke amount estimation calculation unit 11e becomes the feedforward control value. Also, the correction value calculated by the suspension stroke amount correction value calculation unit 11f becomes the feedback correction value. As described above, there is a slight time lag between this feedforward control value and the feedback correction value. However, since the suspension stroke amount is feedforward controlled, the feedback control value becomes a relatively small value, and high responsiveness can be obtained.

[0066] The present invention is not limited to the above-mentioned embodiments. For example, the toe adjustment actuator 5 may be interposed between the other end of the left tie rod 3l and one end of the tie rod end 4l. In this case, the action of the left tire Fl side and the action of the right tire Fr side in the first embodiment are reversed. Also, although each embodiment has been described using a convex road surface as an example, it goes without saying that the present invention can be applied to a concave road surface. [Explanation of symbols]

[0067] 1...Steering gear, 2...Steering gear box, 2a…Rack shaft, 3l, 3r…tie rod, 4l, 4r…Tie rod end, 5...Toe adjustment actuator, 6l, 6r…knuckle arm, 7l, 7r…Front arm, 8l, 8r…Front suspension, 9l,9r…hub, 11...Steering control unit (Steering_ECU), 11a...toe adjustment amount calculation unit, 11b... tire input load estimation calculation unit, 11c... tire input load correction value calculation unit, 11e...suspension stroke amount estimation calculation unit, 11f...suspension stroke amount correction value calculation unit, 12l, 12r...Tire load sensor, 13l, 13r…Suspension stroke sensor, Fl,Fr…Tires, Plx,Prx…front and rear loads, Ply,Pry…lateral load, Plz,Prz…Vertical load, Xl, Xr…Suspension stroke amount,

Claims

1. A steering device for a vehicle that applies a driving force to a steering wheel to offset a toe change caused by a road surface unevenness, A pair of road reaction force detection units that detect road reaction forces acting on tires attached to the left and right steered wheels; A toe adjustment actuator connected to one of the left and right steering wheels; A control unit that controls the driving force of the toe adjustment actuator; having The control unit is a left / right toe change amount setting unit that sets the toe change amount of the tires attached to the left and right steered wheels, based on the individual road surface reaction forces acting on the left and right tires detected by the road surface reaction force detection units; A difference calculation unit that calculates a difference between the toe change amounts set by the left and right toe change amount setting unit; an actuation amount calculation unit that calculates an actuator actuation amount that offsets the difference calculated by the difference calculation unit; a drive unit that drives the toe adjustment actuator with the actuator operation amount calculated by the operation amount calculation unit; A vehicle steering device comprising:

2. The difference calculation unit The toe change amount on the side where the toe adjustment actuator is provided is calculated based on the toe change amount on the side where the toe adjustment actuator is not provided, which is set by the left / right toe change amount setting unit.

2. A vehicle steering system according to claim 1.

3. Each of the road reaction force detection units is a tire load sensor for detecting an input load applied to the tire; a suspension stroke sensor that detects the vertical load received by the tire from the amount of suspension stroke; 2. The steering system for a vehicle according to claim 1, further comprising:

4. The tire load sensor measures the load in the front-rear direction and the lateral direction applied to the left and right tires.

4. A vehicle steering system according to claim 3.

5. A driving environment information acquisition unit that acquires driving environment information in front of the vehicle, The control unit is an estimation calculation unit that detects the road surface unevenness ahead of the vehicle based on the driving environment information acquired by the driving environment information acquisition unit, and calculates an estimated road surface reaction force that is applied to the tires when the vehicle passes over the road surface unevenness based on the road surface unevenness; a correction value calculation unit that calculates a correction value for correcting the estimated road surface reaction force based on the road surface reaction force detected by the road surface reaction force detection unit; a correction unit that corrects the estimated road surface reaction force obtained by the estimation calculation unit with the correction value calculated by the correction value calculation unit to calculate a new road surface reaction force; Equipped with The lateral toe change amount setting unit sets the toe change amount based on the new road surface reaction force calculated by the correction unit.

2. A vehicle steering system according to claim 1.

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