JP2005067455A - Controlling device for electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively reduce a torque steer resulting from a braking/driving force difference of right and left wheels by controlling a steering assistant torque, and at the same time, to effectively reduce the behavior deterioration of a vehicle. <P>SOLUTION: A basic assistant torque Tab is calculated based on a steering torque Ts and a vehicle velocity V (S20 to 40). A torque steer reduction torque Tts for promoting the steering in the direction to offset a torque steer resulting from a braking/driving force difference of the right and left wheels is calculated (S50). A behavior deterioration reducing torque Tvs for promoting the steering in the direction for reducing an over steer state or an under steer state of the vehicle is calculated (S80). When the magnitude of the torque steer reduction torque Tts is less than a reference value Ttso, A target assistant torque Ta is calculated based on the sum of Tab, Tts and Tvs. When the magnitude of the torque steer reduction torque Tts is at the reference value Ttso or higher, the target assistant torque Ta is calculated based on the sum of Tab and Tts (S100 to 120). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electric power steering device for a vehicle, and more particularly to a control device for an electric power steering device.

  In a vehicle such as an automobile, as one of control devices for an electric power steering device that reduces a steering burden on a driver by applying a steering assist torque, for example, as described in Patent Document 1 below, Estimated to generate torque steer reduction torque that promotes steering in the direction to offset torque steer caused by the difference in braking / driving force between left and right wheels when the vehicle travels on a so-called straddle road with different friction coefficients on the left and right road surfaces 2. Description of the Related Art Conventionally, a control device for an electric power steering device configured to control an electric power steering device based on a braking / driving force difference between left and right wheels is known.

  According to such a control device for an electric power steering device, the electric power steering device is controlled so as to generate a torque steer reducing torque that promotes steering in a direction that cancels the torque steer caused by the difference in braking / driving force between the left and right wheels. Therefore, it is possible to improve the straight traveling performance of the vehicle and the traveling stability of the vehicle as compared with the case where such control is not performed.

Also, when the vehicle is oversteered or understeered, it is based on the estimated behavioral state of the vehicle so as to generate a behavior deterioration reducing torque that promotes steering in the direction of reducing the oversteered state or understeered state of the vehicle. It has also been conventionally known that controlling an electric power steering device is effective in reducing deterioration of vehicle behavior due to an oversteer state or an understeer state.
JP 2001-80535 A

  In general, (1) the torque steer reducing torque during braking of the vehicle and (2) the torque steer reducing torque during driving of the vehicle must be generated simultaneously, or (3) the behavior of reducing the oversteer state of the vehicle There is no situation in which the deterioration reducing torque and (4) the behavior deterioration reducing torque for reducing the understeer state of the vehicle must be generated at the same time.

  On the other hand, for example, when the vehicle turns on a crossing road, (1) Torque reduction torque when braking the vehicle and (3) Deterioration behavior deterioration torque that reduces the oversteer state of the vehicle or (4) Understeer of the vehicle A situation in which a behavior deterioration reduction torque for reducing the state must be generated simultaneously; (2) a torque steer reduction torque during driving of the vehicle; and (3) a behavior deterioration reduction torque for reducing the oversteer state of the vehicle (4 ) There may be situations where a behavioral deterioration reducing torque that reduces the understeer state of the vehicle must be generated at the same time.

  However, in the conventional control device for an electric power steering device as described above, torque steer reducing torque that promotes steering in a direction to cancel torque steer due to the braking / driving force difference between the left and right wheels is generated, and When controlling an electric power steering device to generate a behavior deterioration reduction torque that promotes steering in a direction to reduce the oversteer state or understeer state of the vehicle, both the torque steer reduction torque and the behavior deterioration reduction torque However, there is a room for improvement in this respect, since no study has been made on how to control the electric power steering apparatus when it is necessary to generate the power.

  The above-mentioned points to be improved are, for example, vehicles that are caused by the difference in braking / driving force between the left and right wheels in order to reduce changes in vehicle behavior caused by the difference in braking / driving force between the left and right wheels when the vehicle travels on a crossing road The same applies to the case where the electric power steering apparatus is controlled so as to generate a behavior change reducing torque that promotes steering in a direction of reducing the behavior change.

  The present invention reduces the influence of a braking / driving force difference that cancels torque steer caused by a difference in braking / driving force between left and right wheels or promotes steering in a direction that reduces changes in vehicle behavior caused by the difference in braking / driving force between left and right wheels. The technical problems as described above in controlling the electric power steering apparatus so as to generate a torque and a behavior deterioration reducing torque that promotes steering in a direction of reducing the oversteer state or the understeer state of the vehicle. The main object of the present invention is to control the left and right wheels by appropriately controlling the electric power steering device based on the braking / driving force difference effect reducing torque and the behavior deterioration reducing torque. Effectively reduces torque steer and changes in vehicle behavior due to force differences and effectively reduces vehicle oversteer or understeer conditions. It is.

  According to the present invention, the main problem described above is that, according to the present invention, the means for calculating the basic assist torque based on at least the steering torque and the control for promoting the steering in the direction of reducing the influence of the braking / driving force difference between the left and right wheels on the vehicle. Means for calculating a driving force difference effect reducing torque, means for calculating a behavior deterioration reducing torque for promoting steering in a direction to reduce an oversteer state or an understeer state of the vehicle, the basic assist torque and the braking / driving force difference A control device for an electric power steering device, comprising: a target assist torque calculating means for calculating a target assist torque based on the influence reducing torque or the behavior deterioration reducing torque, and controlling the electric power steering device based on the target assist torque Then, the target assist torque calculation means calculates the magnitude of the braking / driving force difference effect reducing torque. The control device for an electric power steering apparatus, wherein when the value is equal to or greater than a reference value, the target assist torque is calculated based on a sum of the basic assist torque and the braking / driving force difference effect reducing torque (structure of claim 1) Or means for calculating a basic assist torque based on at least the steering torque, and means for calculating a braking / driving force difference effect reducing torque that promotes steering in a direction to reduce the influence of the braking / driving force difference between the left and right wheels with respect to the vehicle; A means for calculating a behavior deterioration reducing torque that promotes steering in a direction to reduce the oversteer state or the understeer state of the vehicle, and the basic assist torque and the braking / driving force difference effect reducing torque or the behavior deterioration reducing torque. Target assist torque calculating means for calculating the target assist torque, the target assist torque The target assist torque calculating means is configured to control the behavior when the magnitude of the braking / driving force difference effect reducing torque is equal to or greater than a reference value. The target assist torque is calculated based on the basic assist torque, the braking / driving force difference effect reducing torque, and the weight sum of the behavior deterioration reducing torque, in which the weight of the braking / driving force difference effect reducing torque is larger than the deterioration reducing torque. The control device for an electric power steering device (configuration of claim 2) characterized by: or means for calculating a basic assist torque based on at least the steering torque; and the influence of the braking / driving force difference between the left and right wheels on the vehicle. Means for calculating the braking / driving force difference effect reducing torque that promotes steering in the direction of reduction, and oversteering of the vehicle Calculating a behavior deterioration reducing torque that promotes steering in a direction to reduce the state or understeer state, and calculating a target assist torque based on the basic assist torque and the braking / driving force difference effect reducing torque or the behavior deterioration reducing torque And a target assist torque calculating means for controlling the electric power steering device based on the target assist torque, wherein the target assist torque calculating means includes the basic assist torque, This is achieved by a control device for an electric power steering device (composition of claim 3) that calculates the target assist torque based on the sum of braking / driving force difference effect reducing torque and behavior deterioration reducing torque.

  Further, according to the present invention, in order to effectively achieve the main problems described above, in the configuration of the first to third aspects, the target assist torque calculating means has a magnitude of the braking / driving force difference effect reducing torque. Is less than the reference value, the target assist torque is calculated based on the sum of the basic assist torque, the braking / driving force difference effect reducing torque, and the behavior deterioration reducing torque (configuration of claim 4).

  According to the present invention, in order to effectively achieve the above-described main problems, in the configuration of the above-described claims 1 to 4, the target assist torque calculation means is configured such that the magnitude of the target assist torque is an upper limit reference value. When it exceeds, the magnitude of the target assist torque is limited to the upper limit reference value (structure of claim 5).

  According to the present invention, in order to effectively achieve the main problems described above, the braking / driving force difference effect reducing torque is caused by the braking / driving force difference between the left and right wheels. The torque steer is reduced so as to promote the steering in the direction to cancel the torque steer.

  According to the present invention, in order to effectively achieve the main problems described above, the braking / driving force difference effect reducing torque is caused by the braking / driving force difference between the left and right wheels. It is configured to be a behavior change reducing torque that promotes steering in a direction to reduce a change in vehicle behavior.

  In general, the torque steer when the vehicle travels on a crossing road and the change in the vehicle behavior caused by the steer progress more rapidly than the deterioration of the vehicle behavior due to the vehicle being in an oversteer state or an understeer state. Deterioration of vehicle behavior due to oversteering or understeering of the vehicle can be reduced by controlling the braking force of the wheel, but change of vehicle behavior due to torque steering should be reduced by controlling the braking force of the wheel. Then, the braking force of the wheel having the higher friction coefficient has to be reduced, leading to an increase in the braking distance of the vehicle. Therefore, when it is necessary to generate both the braking / driving force difference effect reducing torque and the behavior deterioration reducing torque, it is preferable that the braking / driving force difference effect reducing torque is selected if any of these is selected. .

  According to the first aspect of the present invention, when the magnitude of the braking / driving force difference effect reducing torque is equal to or larger than the reference value and there is a possibility that the behavior of the vehicle is abruptly changed due to the torque steer, the basic assist torque Since the target assist torque is calculated based on the sum of the braking / driving force difference effect reducing torque, the target assist torque is calculated by giving priority to the braking / driving force difference effect reducing torque over the behavior deterioration reducing torque. This can effectively prevent the behavior of the vehicle from changing suddenly.

  Further, according to the configuration of the second aspect, when the magnitude of the braking / driving force difference effect reducing torque is equal to or larger than the reference value and there is a possibility that the behavior of the vehicle is abruptly changed due to the torque steer, the behavior is deteriorated. Since the target assist torque is calculated based on the weighted sum of the basic assist torque, the braking / driving force difference effect reducing torque, and the behavior deterioration reducing torque, the weight of the braking / driving force difference effect reducing torque being larger than the reduced torque. It is possible to effectively prevent the behavior of the vehicle from changing suddenly due to torque steer while reducing the possibility of excessive torque.

  According to the third aspect of the present invention, since the target assist torque is calculated based on the sum of the basic assist torque, the braking / driving force difference effect reducing torque, and the behavior deterioration reducing torque, the magnitude of the braking / driving force difference effect reducing torque is large. It is not necessary to switch the calculation of the target assist torque based on the above, and it is possible to simplify the control, and the value of the target assist torque changes rapidly, and the driver feels uncomfortable due to this. This can be surely prevented.

  According to the fourth aspect of the present invention, when the magnitude of the braking / driving force difference effect reducing torque is less than the reference value, the target assist is based on the sum of the basic assist torque, the braking / driving force difference effect reducing torque, and the behavior deterioration reducing torque. Since the torque is calculated, it is possible to effectively prevent the vehicle behavior from abruptly changing due to the torque steer while effectively preventing the deterioration of the vehicle behavior due to the vehicle being oversteered or understeered. Can be prevented.

  According to the fifth aspect of the present invention, when the magnitude of the target assist torque exceeds the upper limit reference value, the magnitude of the target assist torque is limited to the upper limit reference value. It is possible to surely prevent excess, and compared with the case where such guard processing is not performed, the ratio of the magnitude of the braking / driving force difference effect reducing torque to the braking / driving force difference between the left and right wheels and the vehicle The ratio of the magnitude of the behavior deterioration reducing torque to the degree of the oversteer state or the understeer state can be increased, and thereby the braking / driving force difference effect reducing effect and the behavior deterioration reducing effect can be increased.

  Further, according to the configuration of the sixth aspect, the braking / driving force difference effect reducing torque is a torque steer reducing torque that promotes steering in a direction that cancels out the torque steer due to the braking / driving force difference between the left and right wheels. It is possible to reduce the influence of the steer, thereby effectively preventing the vehicle behavior from changing suddenly.

  According to the seventh aspect of the present invention, the braking / driving force difference effect reducing torque is a torque steer reducing torque that promotes steering in a direction that reduces a change in vehicle behavior caused by the braking / driving force difference between the left and right wheels. In this way, the influence of the braking / driving force difference between the left and right wheels can be reduced, whereby the behavior of the vehicle can be effectively maintained in a stable state.

[Preferred embodiment of problem solving means]
According to one preferred aspect of the present invention, in the configuration of the first to fifth aspects, the means for calculating the braking / driving force difference effect reducing torque is directed to reducing the influence of the braking force difference between the left and right wheels on the vehicle. The braking force difference effect reducing torque is the sum of the braking force difference effect reducing torque for promoting the steering of the vehicle and the driving force difference effect reducing torque for promoting the steering in the direction to reduce the influence of the driving force difference between the left and right wheels with respect to the vehicle. (Preferred aspect 1).

  According to another preferred aspect of the present invention, in the configuration of the above first to fifth aspects, the means for calculating the behavior deterioration reducing torque is an overspeed that promotes steering in a direction to reduce the oversteer state of the vehicle. The behavior deterioration reducing torque is configured to be calculated as the sum of the steering deterioration deterioration torque and the understeer behavior deterioration reducing torque that promotes steering in the direction of reducing the understeer state of the vehicle (preferred aspect 2).

  According to another preferred aspect of the present invention, in the configuration of the first to fifth aspects or the preferred aspect 2, the means for calculating the behavior deterioration reducing torque is steered in the direction opposite to the turning direction of the vehicle. The oversteer behavior deterioration reducing torque is calculated as an auxiliary steering torque that promotes (preferred aspect 3).

  According to another preferred aspect of the present invention, in the configuration of the first to fifth aspects or the preferred aspect 2, the means for calculating the behavior deterioration reducing torque is an understeer as an auxiliary steering torque for increasing the steering reaction force. It is comprised so that a time behavior deterioration reduction torque may be calculated (Preferred aspect 4).

  According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 4, the means for calculating the behavior deterioration reducing torque is such that the degree of the understeer state of the vehicle is greater than or equal to the first reference value and the second reference value. Is less than the reference value, the understeering behavior deterioration reducing torque is calculated as an auxiliary steering torque for reducing the steering reaction force (preferred aspect 5).

  According to another preferred aspect of the present invention, in the configuration of the first or second aspect of the invention, the target assist torque calculating means is configured such that the magnitude of the torque steering reduction torque is between the reference value and the reference value. When changing, an asymptotic process for reducing the rate of change of the target assist torque is performed (preferred aspect 6).

  According to another preferred aspect of the present invention, in the configuration of claim 2, the target assist torque calculating means increases the braking / driving force difference effect reducing torque as the magnitude of the braking / driving force difference effect reducing torque increases. It is comprised so that a weight may be enlarged (the preferable aspect 7).

  According to another preferred aspect of the present invention, in the configuration of the preferred aspect 1, the means for calculating the braking / driving force difference effect reducing torque is a braking force difference according to the braking force difference between the left and right wheels and the road surface condition. It is comprised so that influence reduction torque may be calculated (Preferred aspect 8).

  According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 8, the road surface condition is determined based on the deceleration of the vehicle (preferred embodiment 9).

  According to another preferred aspect of the present invention, in the configuration of the preferred aspect 8, when the vehicle deceleration is small, the magnitude of the braking force difference effect reducing torque is larger than when the vehicle deceleration is large. (Preferred aspect 10).

  According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 8, the difference in braking force between the left and right wheels is determined based on at least the braking force difference between the left and right front wheels (preferred embodiment). 11).

  According to another preferred aspect of the present invention, in the configuration of the preferred aspect 8, the difference in braking force between the left and right wheels is reduced more than the difference in braking force between the left and right front wheels and the braking force difference between the left and right front wheels. The determination is made based on the sum of the braking force difference between the left and right rear wheels (preferred aspect 12).

  According to another preferred aspect of the present invention, in the configuration of the preferred aspect 8, the means for calculating the braking / driving force difference effect reducing torque is in a situation where the anti-skid control is being executed for at least one wheel. Thus, the braking force difference effect reducing torque is calculated according to the braking force difference between the left and right wheels and the road surface condition (preferred aspect 13).

  According to another preferred aspect of the present invention, in the configuration of the preferred aspect 9, the magnitude of the braking force difference effect reducing torque is increased as the friction coefficient of the road surface having a higher road surface friction coefficient is higher. (Preferred embodiment 14).

  According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 10 described above, the road surface condition is based on the deceleration of the vehicle in a situation where the anti-skid control is being performed for at least one wheel. It is configured to be determined (preferred aspect 15).

  According to another preferred aspect of the present invention, in the configuration of the preferred aspect 11, the braking force difference effect reducing torque is controlled to zero when the vehicle deceleration is equal to or lower than a lower limit reference value. (Preferred embodiment 16).

  According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 10 or the preferred embodiment 16, the braking force difference effect reducing torque is controlled to 0 when the deceleration of the vehicle is equal to or higher than the upper limit reference value. (Preferred embodiment 17).

  According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 11, the difference in braking force between the left and right wheels is determined based on at least the braking pressure difference between the left and right front wheels (preferred embodiment 18). ).

  According to another preferred aspect of the present invention, in the configuration of the preferred aspect 12, the right and left rear braking force difference between the left and right front wheels and the left and right front wheel braking pressure difference is reduced in weight. It is comprised so that it may determine based on the sum with the braking pressure difference of a wheel (preferable aspect 19).

  The present invention will now be described in detail with reference to a few preferred embodiments with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing a first embodiment of a control device for an electric power steering apparatus according to the present invention.

  In FIG. 1, 10 FL and 10 FR respectively indicate left and right front wheels that are driven wheels of the vehicle 12, and 10 RL and 10 RR respectively indicate left and right rear wheels that are drive wheels of the vehicle 12. The left and right front wheels 10FL and 10FR, which are also steered wheels, are steered via tie rods 18L and 18R by a rack-and-pinion type electric power steering device 16 driven in response to steering of the steering wheel 14 by the driver. The

  In the illustrated embodiment, the electric power steering device 16 is a rack coaxial type electric power steering device and is controlled by the electronic control unit 20. The electric power steering device 16 includes an electric motor 22 and a conversion mechanism 26 of, for example, a ball screw type that converts the rotational torque of the electric motor 22 into a force in the reciprocating direction of the rack bar 24. By generating an auxiliary turning force that drives the bar 24, a steering assist torque that reduces the steering burden on the driver is generated.

  The braking force of each wheel is controlled by controlling the braking pressure of the wheel cylinders 34FR, 34FL, 34RR, 34RL by the hydraulic circuit 32 of the braking device 30. Although not shown in the drawing, the hydraulic circuit 32 includes a reservoir, an oil pump, various valve devices, and the like, and the braking pressure of each wheel cylinder is normally driven in accordance with the depression operation of the brake pedal 36 by the driver. It is controlled by the master cylinder 38 and is controlled by the electronic control unit 40 as necessary. The electronic control unit 20 and the electronic control unit 40 exchange necessary information with each other. The electronic control unit 40 cooperates with the electronic control unit 20 in the technical field when the behavior of the vehicle deteriorates. By controlling the braking force of a predetermined wheel in a known manner, behavior control for stabilizing the behavior of the vehicle is performed.

  The steering shaft 42 is provided with a steering angle sensor 44 for detecting the steering angle θ and a torque sensor 46 for detecting the steering torque Ts. The vehicle 12 has a vehicle speed sensor 48 for detecting the vehicle speed V, and a yaw rate for detecting the yaw rate γ of the vehicle. A sensor 50, a longitudinal acceleration sensor 52 for detecting the longitudinal acceleration Gx of the vehicle, and a lateral acceleration sensor 54 for detecting the lateral acceleration Gy of the vehicle are provided. The steering angle sensor 44, the torque sensor 46, the yaw rate sensor 50, and the lateral acceleration sensor 54 detect the steering angle θ, the steering torque Ts, the yaw rate γ, and the lateral acceleration Gy, respectively, with the left turning direction of the vehicle being positive.

  As shown in the figure, a signal indicating the steering angle θ detected by the steering angle sensor 44, a signal indicating the steering torque Ts detected by the torque sensor 46, and a signal indicating the vehicle speed V detected by the vehicle speed sensor 48 are the electronic control unit 20. The signal indicating the yaw rate γ detected by the yaw rate sensor 50, the signal indicating the longitudinal acceleration Gx detected by the longitudinal acceleration sensor 52, and the signal indicating the lateral acceleration Gy detected by the lateral acceleration sensor 54 are 40. Although not shown in detail in the figure, the electronic control devices 20 and 40 have, for example, a CPU, a ROM, a RAM, and an input / output port device, which are connected to each other by a bidirectional common bus. Includes component microcomputer.

  The electronic control unit 20 calculates a basic assist torque Tab for reducing the driver's steering burden based on the steering torque Ts and the vehicle speed V according to the flowchart shown in FIG. A torque steer reduction torque Tts that promotes steering in a direction that cancels out the torque steer, and a behavior deterioration reduction torque Tvs that promotes steering in a direction to reduce the oversteer state or understeer state of the vehicle. When the magnitude of the steering reduction torque Tts is less than the reference value, the target assistance torque Ta is calculated based on the sum of the basic assistance torque Tab, the torque steering reduction torque Tts, and the behavior deterioration reduction torque Tvs, and the magnitude of the torque steering reduction torque Tts. Is greater than the reference value, the target is based on the sum of the basic assist torque Tab and the torque steer reduction torque Tts. The assist torque Ta is calculated, and the electric power steering device 16 is controlled based on the target assist torque Ta, thereby controlling the steering assist torque.

  In particular, in the illustrated embodiment, the electronic control unit 20 limits the magnitude of the target assist torque Ta to the reference value when the absolute value of the target assist torque Ta is larger than the reference value and excessively large. When the magnitude of the torque steer reduction torque Tts changes between a situation where it is less than the reference value and a situation where it is greater than or equal to the reference value, a sudden change in the magnitude of the target assist torque Ta is prevented. Asymptotic processing is performed.

  In the illustrated embodiment, the electronic control unit 20 also applies braking torque steer reducing torque Tbts for facilitating steering in a direction to cancel torque steer caused by the difference in braking force between the left and right wheels, and driving of the left and right wheels. The torque steer reduction torque Tts is calculated as the sum of the driving torque steer reduction torque Tdts that promotes steering in a direction that cancels out the torque steer due to the force difference.

  In addition, the electronic control unit 20 reduces the oversteer behavior deterioration reducing torque Tovs that promotes steering in a direction that reduces the oversteer state of the vehicle, and understeer behavior deterioration that promotes steering in the direction that reduces the understeer state of the vehicle. The behavior deterioration reduction torque Tvs is calculated as the sum of the reduction torque Tuvs.

  Although not shown in the drawing as a flowchart, the electronic control unit 40 is based on the wheel speed Vwi of each wheel in the manner known in the art, and the vehicle body speed Vb and the braking slip amount SBi (i of each wheel). = Fl, fr, rl, rr), and when the braking slip amount SBi of any wheel becomes larger than the reference value for starting anti-skid control (ABS control) and anti-skid control start conditions are met, Anti-skid control is performed to increase or decrease the pressure in the wheel cylinder so that the braking slip amount is within a predetermined range until the skid control end condition is satisfied.

  Further, the electronic control unit 40 calculates the vehicle body speed Vb and the acceleration slip amounts SAfrl and SArr of the left and right rear wheels based on the wheel speed Vwi of each wheel, as known in the art, and the acceleration slip amount SArl or SArr is calculated. When the traction control start condition is satisfied when the traction control start condition is satisfied and the traction control start condition is satisfied, the wheel cylinder is set so that the acceleration slip amount is within a predetermined range until the traction control end condition is satisfied. Traction control is performed to increase or decrease the pressure in 34FL, 34FR.

  Further, the electronic control unit 40 calculates a spin state quantity SS indicating the degree of vehicle spin and a drift-out state quantity DS indicating the degree of vehicle drift-out based on the vehicle state quantity that changes as the vehicle travels. Calculates the target braking force or target slip ratio of each wheel for behavior control that stabilizes the behavior of the vehicle based on the SS and the drift-out state quantity DS, and relates to the braking operation of the driver using the pressure of the high pressure source. Instead, the braking pressure of each wheel is controlled in accordance with the target braking force or the target slip ratio, and thereby the braking force is applied to a predetermined wheel to stabilize the behavior of the vehicle.

  For example, when the vehicle is in the spin state, the electronic control unit 40 suppresses the spin by applying a braking force to the outer front wheel to give the vehicle a yaw moment in the spin suppression direction, and when the vehicle is in the drift-out state, The braking force is applied to the left and right rear wheels to decelerate the vehicle, and the vehicle is given a yaw moment in the turning assist direction to suppress drift-out. Since anti-skid control, traction control, and behavior control itself do not form the gist of the present invention, each of these controls may be executed in any manner known in the art.

  Next, the steering assist torque control in the first embodiment will be described with reference to the flowcharts shown in FIGS. The control according to the flowchart shown in FIG. 2 is started by closing an ignition switch (not shown), and is repeatedly executed at predetermined time intervals until the ignition switch is opened.

  First, at step 10, a signal indicating the steering angle θ is read, and at step 20, the basic assist torque Tab ′ increases as the steering torque Ts increases, based on the steering torque Ts. Based on the vehicle speed V, the basic assist torque Tab ′ is calculated from the map corresponding to the graph shown in FIG. 5 so that the vehicle speed coefficient Kv decreases as the vehicle speed V increases in step 30. The vehicle speed coefficient Kv is calculated from the map corresponding to the graph, and in step 40, the basic assist torque Tab corrected by the vehicle speed coefficient is calculated as the product of the vehicle speed coefficient Kv and the basic assist torque Tab ′.

  In step 50, the torque steer reduction torque Tts is calculated according to the flowchart shown in FIG. 3, and in step 80, the behavior deterioration reduction torque Tvs is calculated according to the flowchart shown in FIG.

  In step 100, it is determined whether or not the absolute value of the torque steer reducing torque Tts is larger than a reference value Ttso (positive constant). If a negative determination is made, the basic assist torque is determined in step 110. The target assist torque Ta is calculated as the sum of Tab, torque steer reduction torque Tts, and behavior deterioration reduction torque Tvs. If an affirmative determination is made, the target is obtained as the sum of basic assist torque Tab and torque steer reduction torque Tts in step 120. An assist torque Ta is calculated.

  In step 200, the target assist torque Ta is switched between steps 110 and 120 because the determination in step 100 is switched between negative determination and positive determination. In order to prevent a sudden change in the value of the torque Ta, for example, the value of the target assist torque Ta is gradually changed from the value before switching to the value after switching by a change rate guard process or a filter process as necessary. Asymptotic processing of the target assist torque Ta is performed.

  In step 210, it is determined whether or not the absolute value of the target assist torque Ta is larger than a reference value Tao (positive constant), that is, whether or not the magnitude of the target assist torque Ta is excessive. If a negative determination is made, the process proceeds directly to step 230. If an affirmative determination is made, the process proceeds to step 220.

  In step 220, sign Ta is set as the sign of the target assist torque Ta, the target assist torque Ta is set to Tao / sign Ta, and in step 230, a control signal corresponding to the target assist torque Ta is output to the motor 22. As a result, steering assist torque control for reducing the steering force necessary for the driver is executed.

  In step 52 of the torque steer reduction torque Tts calculation routine shown in FIG. 3, whether or not the driver is performing a braking operation by determining whether or not the master cylinder pressure Pm is greater than or equal to a reference value, for example. That is, that is, whether or not braking is being performed. When a negative determination is made, the process proceeds to step 60, and when an affirmative determination is made, the process proceeds to step 54.

In step 54, for example, the braking pressure difference ΔP between the left and right wheels is calculated as the difference Pfl−Pfr in the braking pressure between the left and right front wheels. The left and right wheel braking pressure difference ΔP is weighted with respect to the braking pressure difference between the left and right rear wheels Kr (for example, a positive value larger than 0 and smaller than 1 such as 0.5). Accordingly, the weight of the braking pressure difference between the left and right rear wheels may be calculated as the sum of these weights reduced with respect to the braking pressure difference between the left and right front wheels.
ΔP = Pfl−Pfr + Kr (Prl−Prr) (1)

  In step 56, it is determined whether or not anti-skid is performed on at least one wheel. If a negative determination is made, the process proceeds to step 60. If an affirmative determination is made, the process proceeds to step 58.

  In step 58, it is determined whether the vehicle deceleration Gbx (= -Gx) is larger than the lower limit reference value Gbx1 and smaller than the upper limit reference value Gbx2, and if a negative determination is made, the process goes to step 60. When the braking torque steer reducing torque Tbts is set to 0 and an affirmative determination is made, the routine proceeds to step 62.

  Note that the lower limit reference value Gbx1 is a value of about −0.2 g where g is the gravitational acceleration, and is suppressed by the vehicle due to a detection error of the pressure sensor, a variation in the relationship between the braking pressure and the braking force, and the like. The electric power steering device is unnecessarily controlled on the basis of the braking force difference between the left and right wheels, and unnecessary torque steer reduction torque is generated even though the torque steer and behavior change are not generated. This is a reference value for preventing this. Further, the upper reference value Gbx2 does not increase the difference in braking force between the left and right wheels in a situation where a high deceleration occurs. In this situation, the electric power steering device is based on the difference in braking force between the left and right wheels. Is a reference value for preventing unnecessary control and generation of unnecessary torque steer reduction torque.

  In step 62, as the braking pressure difference ΔP between the left and right wheels increases, the braking torque steer reduction torque Tbts increases, and as the vehicle deceleration Gbx increases, the braking torque steer reduction torque Tbts increases. The braking torque steer reduction torque Tbts is calculated from a map corresponding to the graph indicated by the bold line in FIG. 7 based on the braking pressure difference ΔP between the left and right wheels and the vehicle deceleration Gbx.

  In step 64, it is determined whether or not traction (TRC) control is being performed. If a negative determination is made, the process proceeds to step 68. If an affirmative determination is made, the process proceeds to step 66.

  In step 66, the driving force difference ΔFdr between the left and right rear wheels, which is the driving wheel, is estimated in a manner known in the art, and the absolute value of the driving force difference ΔFdr between the left and right rear wheels is the reference value ΔFdro. Whether the torque steer during driving is excessive or not is determined, and if a negative determination is made, in step 68, when driving, When the torque steer reduction torque Tdts is set to 0 and an affirmative determination is made, in step 70, Kdts is set as a positive constant coefficient, and the driving torque steer reduction torque Tdts is calculated as the product of Kdts and ΔFdr.

  In step 72, the torque steer reducing torque Tts is calculated as the sum of the braking torque steer reducing torque Tbts and the driving torque steer reducing torque Tdts, and then the routine proceeds to step 80.

  In step 82 of the behavior deterioration reducing torque Tvs calculation routine shown in FIG. 4, the deviation of the lateral acceleration, that is, the lateral slip acceleration of the vehicle, is obtained as a deviation Gy−γV between the lateral acceleration Gy and the product γV of the vehicle speed V and the yaw rate γ. Vyd is calculated, and the side slip acceleration Vyd is integrated to calculate the side slip speed Vy of the vehicle body. Further, the ratio of the vehicle body side slip velocity Vy to the vehicle longitudinal speed Vx (= vehicle speed V) is Vy / Vx. β is calculated.

  In step 84, the spin amount SV is calculated as the linear sum K1β + K2Vyd of the vehicle body slip angle β and side slip acceleration Vyd, with K1 and K2 being positive constants, and the turning direction of the vehicle is determined based on the sign of the yaw rate γ. The spin state amount SS is calculated as SV when the vehicle is turning left, and is -SV when the vehicle is turning right, and the spin state amount is 0 when the calculation result is a negative value. The spin amount SV may be calculated as a linear sum of the vehicle body slip angle β and its differential value βd.

  8 corresponds to the graph shown in FIG. 8 based on the spin state quantity SS so that the magnitude of the oversteer (OS) behavior deterioration reducing torque Tovs increases as the magnitude of the spin state quantity SS increases. The oversteer behavior deterioration reducing torque Tovs is calculated from the map.

In step 88, the actual steering angle δ of the front wheels is calculated based on the steering angle θ, the target yaw rate γe is calculated according to the following equation 2 using H as the wheel base and Kh as the stability factor, and T is the time constant. Assuming that s is a Laplace operator, an estimated yaw rate γt of the vehicle based on the vehicle speed V and the steering angle θ is calculated according to the following equation (3). The target yaw rate γe may be calculated in consideration of the lateral acceleration Gy of the vehicle so as to take into account the dynamic yaw rate.
γe = Vδ / {(1 + KhV ² ) H} (2)
γt = γe / (1 + Ts) (3)

In step 90, the drift value DV is calculated according to the following equation 4, the turning direction of the vehicle is determined based on the sign of the yaw rate γ, and the drift-out state quantity DS is set as DV when the vehicle turns left. When turning right, it is calculated as -DV, and when the calculation result is a negative value, the drift-out state quantity is zero. The drift value DV may be calculated according to the following formula 5.
DV = (γt−γ) (4)
DV = H (γt−γ) / V (5)

  In step 92, the graph shown in FIG. 9 is based on the drift-out state quantity DS so that the magnitude of the understeer (US) behavior deterioration reducing torque Tuvs increases as the magnitude of the drift-out state quantity DS increases. Understeering behavior deterioration reducing torque Tuvs is calculated from the corresponding map.

  As shown in FIG. 9, the understeer behavior deterioration reducing torque Tuvs is steered when the magnitude of the drift-out state quantity DS is not less than the first reference value DS1 and not more than the second reference value DS2. It is calculated as an assist torque in a direction to reduce the reaction force, and this informs the driver that the vehicle is approaching the limit of the understeer state due to a decrease in the steering reaction force.

  In step 94, the behavior deterioration reducing torque Tvs is calculated as the sum of the oversteering behavior deterioration reducing torque Tovs and the understeering behavior deterioration reducing torque Tuvs. Thereafter, the routine proceeds to step 100.

  Thus, according to the first embodiment shown in the drawing, the steering torque Ts and the vehicle speed V are set so that the magnitude increases as the steering torque Ts increases in steps 20 to 40 and decreases as the vehicle speed V increases. Based on the above, the basic assist torque Tab is calculated, and in step 50, the torque steer reducing torque Tts that promotes steering in the direction to cancel the torque steer caused by the difference in braking / driving force between the left and right wheels is calculated. Then, a behavior deterioration reducing torque Tvs that promotes steering in a direction to reduce the oversteer state or the understeer state of the vehicle is calculated.

  In steps 100 to 120, when the magnitude of the torque steer reduction torque Tts is less than the reference value Ttso, the target assist torque Ta is calculated based on the sum of the basic assist torque Tab, the torque steer reduction torque Tts, and the behavior deterioration reduction torque Tvs. When the magnitude of the torque steer reduction torque Tts is equal to or greater than the reference value Ttso, the target assist torque Ta is calculated based on the sum of the basic assist torque Tab and the torque steer reduction torque Tts. In step 230, the target assist torque Ta is calculated. The steering assist torque is controlled by controlling the electric power steering device 16 based on this.

  Therefore, when the magnitude of the torque steer reduction torque Tts is equal to or greater than the reference value Ttso and there is a possibility that the behavior of the vehicle is abruptly deteriorated due to the torque steer, the torque steer reduction torque Tts is set to be greater than the behavior deterioration reduction torque Tvs. Since the target assist torque Ta is calculated with priority, it is possible to effectively prevent the behavior of the vehicle from abruptly deteriorating due to torque steer.

  In particular, according to Example 1 shown in the figure, when the magnitude of the torque steer reduction torque Tts is equal to or greater than the reference value Ttso, the sum of the basic assist torque Tab and the torque steer reduction torque Tts without taking the behavior deterioration reduction torque Tvs into consideration. Since the target assist torque Ta is calculated based on the above, the control of the left and right wheels is suppressed as compared with the case where the behavior deterioration reducing torque Tvs is considered even in the situation where the magnitude of the torque steer reducing torque Tts is not less than the reference value Ttso. Even if the ratio of the torque steer reduction torque Tts to the driving force difference is increased, there is a low possibility that the target assist torque Ta is excessively large. Therefore, the ratio of the torque steer reduction torque Tts to the left / right wheel braking / driving force difference is increased. Thus, it is possible to reliably and effectively prevent the behavior of the vehicle from abruptly deteriorating due to torque steer.

  FIG. 10 is a flowchart showing a main routine of steering assist torque control in the second embodiment of the control device for an electric power steering device according to the present invention. In FIG. 10, the same steps as those shown in FIG. 2 are assigned the same step numbers as those shown in FIG.

In the second embodiment, steps 10 to 110 and steps 200 to 230 are executed in the same manner as in the first embodiment, and when an affirmative determination is made in step 100, The target assist torque Ta is calculated according to the following equation 6 with the coefficient K being a positive constant larger than 0.5 and smaller than 1.
Ta = Tab + K.Tts + (1-K) Tvs (6)

  Thus, according to the illustrated second embodiment, when the magnitude of the torque steer reduction torque Tts is equal to or greater than the reference value Ttso, the basic assist torque Tab in which the weight of the torque steer reduction torque Tts is larger than the behavior deterioration reduction torque Tvs. The target assist torque Ta is calculated based on the weight sum of the torque steer reduction torque Tts and the behavior deterioration reduction torque Tvs.

  Therefore, when the magnitude of the torque steer reduction torque Tts is equal to or greater than the reference value Ttso and there is a possibility that the behavior of the vehicle is abruptly deteriorated due to the torque steer, the torque steer reduction torque Tts is greater than the behavior deterioration reduction torque Tvs. Since the target assist torque Ta is calculated based on both of the weights with increasing weight, the behavior of the vehicle is abruptly caused by the torque steer while reducing the possibility of the target assist torque Ta being excessively large. It is possible to effectively prevent the deterioration.

  In the illustrated embodiment 2, the coefficient K is a positive constant, but for example, as shown in FIG. 12, the torque steer reducing torque is increased so that the torque steer reducing torque Tts increases. The torque assist reduction torque Tts may be variably set according to the magnitude of Tts. In this case, the target assist torque increases as the magnitude of the torque steer reduction torque Tts is large and there is a high possibility that the behavior of the vehicle will deteriorate rapidly. The degree of contribution of the torque steer reduction torque Tts to Ta can be increased, thereby more effectively preventing the vehicle behavior from abruptly deteriorating due to torque steer.

  FIG. 11 is a flowchart showing a main routine of steering assist torque control in the third embodiment of the control device for an electric power steering device according to the present invention. In FIG. 11, the same steps as those shown in FIG. 2 are assigned the same step numbers as those shown in FIG.

  Also in the third embodiment, steps 10 to 110 and steps 200 to 230 are executed in the same manner as in the first and second embodiments described above. When step 110 is completed, step 210 is executed, whereby the target assist is executed. The torque Ta is always calculated as the sum of the basic assist torque Tab, the torque steer reduction torque Tts, and the behavior deterioration reduction torque Tvs.

  Thus, according to the illustrated third embodiment, the calculation of the target assist torque Ta is not switched based on the magnitude of the torque steer reduction torque Tts, so that the value of the target assist torque Ta changes abruptly and due to this. Thus, the driver can be surely prevented from feeling uncomfortable, the asymptotic process of step 200 in the first and second embodiments can be omitted, and the operation of the electronic control unit 20 can be omitted. The load can be reduced and the performance required for the component can be reduced.

  According to each embodiment shown in the figure, in steps 210 and 220, guard processing is performed so that the magnitude of the target assist torque Ta does not exceed the reference value Tao, so that the target assist torque Ta is the basic assist torque Tab, torque Even when it is calculated as the sum of the steering reduction torque Tts and the behavior deterioration reduction torque Tvs, it is possible to reliably prevent the target assist torque Ta from being excessively large, and such guard processing is not performed. The ratio of the magnitude of the torque steer reduction torque Tts with respect to the braking / driving force difference between the left and right wheels and the ratio of the magnitude of the behavior deterioration reduction torque Tvs with respect to the vehicle spin state amount SS or the drift-out state amount DS are increased. This can increase the torque steer reduction effect and the behavior deterioration reduction effect.

  Further, according to each embodiment shown in the drawings, in steps 52 to 62, the braking torque steer reduction torque Tbts that promotes steering in a direction to cancel the torque steer caused by the difference in braking force between the left and right wheels is calculated. In 64 to 70, a driving torque steer reduction torque Tdts that promotes steering in a direction that cancels out the torque steer due to the difference in driving force between the left and right wheels is calculated, and in step 72, the torque is calculated as the sum of these torques. Since the steer reduction torque Tts is calculated, the torque steer can be effectively reduced regardless of which torque steer caused by the difference in braking force between the left and right wheels and torque steer caused by the difference in driving force between the left and right wheels occurs. .

  Further, according to each embodiment shown in the figure, in steps 82 to 86, the oversteer behavior deterioration reducing torque Tovs that promotes steering in the direction of reducing the oversteer state of the vehicle is calculated. The understeer behavior deterioration reduction torque Tuvs that promotes steering in the direction of reducing the understeer state of the vehicle is calculated, and the behavior deterioration reduction torque Tvs is calculated as the sum of these torques, so that the vehicle is in the oversteer state and understeer state. The deterioration of the behavior of the vehicle can be effectively reduced in any state.

  Further, according to each of the illustrated embodiments, the understeer behavior deterioration reducing torque Tuvs is steered when the magnitude of the drift-out state quantity DS is not less than the first reference value DS1 and not more than the second reference value DS2. Since it is calculated as an assist torque in a direction to reduce the reaction force, it is possible to notify the driver that the vehicle is approaching the limit of the understeer state by a decrease in the steering reaction force.

  Further, according to the first and second embodiments shown in the drawing, the target assist torque Ta is asymptotically processed as necessary in step 200, so that the calculation of the target assist torque Ta is performed between step 110 and step 120 or 130. Thus, it is possible to effectively prevent the value of the target assist torque Ta from changing suddenly and the driver from feeling uncomfortable due to this change.

  Also, according to the illustrated embodiments, the braking torque steer reduction torque Tbts increases as the braking pressure difference ΔP between the left and right wheels increases, and the braking torque steer reduction torque Tbts increases and the friction coefficient of the road surface. The vehicle deceleration Gbx, which is the index value of the vehicle, is calculated based on the braking pressure difference ΔP between the left and right wheels and the vehicle deceleration Gbx so that the magnitude of the braking torque steer reduction torque Tbts increases. Since Gbx increases as the road friction coefficient increases, the magnitude of the torque steer reduction torque Tbts during braking increases as the friction coefficient of the road surface increases and the magnitude of torque steer resulting from the braking force difference between the left and right wheels increases. Can do.

  Therefore, in a situation where the friction coefficient of the road surface is low and the deceleration of the vehicle is small, the magnitude of the torque steer reduction torque during braking is prevented from being excessive, while the road friction coefficient is high and the deceleration of the vehicle is large. Therefore, it is possible to reliably generate a torque steer reduction torque at the time of braking that is necessary, and compared to the case of calculating the torque steer reduction torque at the time of braking according to only the braking force difference between the left and right wheels. Steer reduction torque can be controlled appropriately.

  Further, according to each of the illustrated embodiments, the braking torque steer reduction torque Tbts is calculated so that the braking torque steer reduction torque Tbts increases as the vehicle deceleration Gbx increases, resulting in a friction coefficient of the road surface. Is determined based on the deceleration Gbx of the vehicle, so that the road surface condition corresponding to the friction coefficient of the road surface can be easily determined.

  Further, according to the illustrated embodiments, not only the magnitude of the braking pressure difference ΔP between the left and right wheels is not more than the reference value ΔPo, but also the vehicle deceleration Gbx is not more than the lower limit reference value Gbx1 or not less than the upper limit reference value Gbx2. Sometimes, the braking torque steer reduction torque Tbts is set to 0 and the braking torque steer reduction torque Tbts is not generated, so that the detection error of the pressure sensor 52i, etc., although the actual torque steer during braking is not high. It is possible to reliably prevent the braking torque steer reducing torque Tbts from being generated unnecessarily in a situation where the magnitude of the braking pressure difference ΔP between the left and right wheels is greater than or equal to the reference value ΔPo due to the above.

  Further, according to each of the illustrated embodiments, the braking torque steer reduction torque Tbts is based on the braking pressure difference ΔP between the left and right wheels and the vehicle deceleration Gbx in a situation where the anti-skid control is executed for at least one wheel. Since the calculation is performed, the braking torque steer reduction torque Tbts can be accurately controlled in accordance with the friction coefficient of the road surface as compared with the case where it is not considered whether or not the anti-skid control is executed.

  Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

  For example, in each of the above-described embodiments, the braking torque steer reduction torque Tbts and the driving are used as the braking / driving force difference effect reducing torque that promotes steering in the direction of reducing the influence of the braking / driving force difference between the left and right wheels with respect to the vehicle. The torque steer reduction torque Tts, which is the sum of the hourly torque steer reduction torque Tdts, is calculated, but the braking / driving force difference effect reducing torque is replaced by the braking / driving force of the left and right wheels instead of the torque steer reduction torque Tts. It may be calculated as a behavior change reduction torque Tvb that promotes steering in a direction to reduce a change in vehicle behavior caused by the difference.

  In this case, the braking behavior change reduction torque Tbvb is calculated based on the braking pressure difference ΔP between the left and right wheels and the vehicle deceleration Gbx, as shown by the thin line in FIG. For example, it is calculated as the product of the coefficient Kdvb larger than the coefficient Kdts in step 70 and the driving force difference ΔFdr between the left and right wheels, and the behavior change reduction torque Tvb is calculated as the braking behavior change reduction torque Tbvb and the driving behavior change reduction torque Tdvb. Or when the vehicle is braked, the braking behavior change reduction torque Tbvb may be calculated as the behavior change reduction torque Tvb. When the vehicle is driven, the driving behavior change reduction torque Tdvb may be calculated as the behavior change reduction torque Tvb. .

  In each of the above embodiments, the torque steer reducing torque Tts is calculated as the sum of the braking torque steer reducing torque Tbts and the driving torque steer reducing torque Tdts. The braking torque steer reduction torque Tbts may be calculated as the torque steer reduction torque Tts, and the driving torque steer reduction torque Tdts may be calculated as the torque steer reduction torque Tts when the vehicle is driven.

  In each of the above-described embodiments, the spin state quantity SS and the drift-out state quantity DS are calculated by the electronic control unit 20, but the electronic control unit 40 has the spin state quantity SS and the drift-out state. When calculating the amount DS and performing behavior control based on the braking / driving force based on the amount DS, the spin state amount SS and the drift-out state amount DS are input from the electronic control unit 40 to the electronic control unit 20 by communication. It may be modified as follows.

  In the first and second embodiments, asymptotic processing of the target assist torque Ta is performed in step 200 as necessary. In each of the above-described embodiments, steps 210 and 220 are performed. In this case, the guard process is performed so that the magnitude of the target assist torque Ta does not exceed the reference value Tao, but the process of step 200 or steps 210 and 220 may be omitted.

  In each of the above-described embodiments, the left-right wheel braking pressure difference ΔP is calculated based on the left-right wheel braking pressure detected by the pressure sensor. It is estimated based on the oil supply / discharge of the cylinder, and may be modified to be calculated based on the estimated braking pressure of the left and right wheels.

  In the above-described embodiments, when the vehicle deceleration Gbx is larger than the lower limit reference value Gbx1 and smaller than the upper limit reference value Gbx2, braking is performed based on the braking pressure difference ΔP between the left and right wheels and the vehicle deceleration Gbx. Although the torque steer reduction torque Tbts is calculated, the determination of whether or not the vehicle deceleration Gbx is smaller than the upper reference value Gbx2 may be omitted.

  In each of the above-described embodiments, the reference value ΔPo of the braking pressure difference ΔP between the left and right wheels is constant regardless of the road surface friction coefficient, and hence the vehicle deceleration Gbx, but the road surface friction coefficient is high. It may be modified so as to be variably set according to the friction coefficient of the road surface or the vehicle deceleration Gbx so that the deceleration Gbx becomes higher.

  In each of the above embodiments, the target assist torque Ta is calculated as the sum of the basic assist torque Tab and the torque steer reduction torque Tts or the behavior deterioration reduction torque Tvs. In addition to these torques, For example, the target assist torque Ta may be corrected so as to be calculated as a value obtained by adding another control torque such as a damping torque that improves the convergence of the steering system.

  Further, in each of the above-described embodiments, the vehicle is a rear wheel drive vehicle, but the vehicle to which the present invention is applied may be a front wheel drive vehicle or a four wheel drive vehicle, and the steering assist torque is arbitrarily set. As long as it can be controlled, the electric power steering apparatus may be of any construction known in the art.

It is a schematic block diagram which shows one Example of the control apparatus for electric power steering apparatuses by this invention. 3 is a flowchart showing a main routine of steering assist torque control in the first embodiment. 6 is a flowchart illustrating a subroutine for calculating a torque steer reduction torque Tts in the first embodiment. 6 is a flowchart illustrating a subroutine of behavior deterioration reducing torque Tvs calculation in the first embodiment. It is a graph which shows the relationship between steering torque Ts and basic assist torque Tab '. It is a graph which shows the relationship between the vehicle speed V and the vehicle speed coefficient Kv. It is a graph which shows the relationship between the braking pressure difference (DELTA) P of a right-and-left wheel, braking torque steer reduction torque Tbts (thick line), and braking behavior change reduction torque Tbvb (thin line). It is a graph which shows the relationship between spin state amount SS and the over-steering behavior deterioration reduction torque Tovs. It is a graph which shows the relationship between drift value DV and under-steering behavior deterioration reduction torque Tuvs. It is a flowchart which shows the main routine of the steering assist torque control in Example 2 of the control apparatus for electric power steering devices by this invention. 10 is a flowchart showing a main routine of steering assist torque control in Embodiment 3 of the control device for an electric power steering device according to the present invention. It is a graph which shows the relationship between the absolute value of the torque steer reduction torque Tts, and the coefficient K.

Explanation of symbols

DESCRIPTION OF SYMBOLS 14 Steering wheel 16 Electric power steering device 20 Electronic control device 30 Braking device 40 Electronic control device 44 Steering angle sensor 46 Torque sensor 48 Vehicle speed sensor 50 Yaw rate sensor 52 Longitudinal acceleration sensor 54 Lateral acceleration sensor

Claims (7)

  Means for calculating basic assist torque based on at least steering torque, means for calculating braking / driving force difference effect reducing torque for promoting steering in a direction to reduce the influence of braking / driving force difference between left and right wheels on the vehicle, and vehicle Means for calculating behavior deterioration reducing torque that promotes steering in a direction to reduce the oversteer state or understeer state of the vehicle, and target assist based on the basic assist torque and the braking / driving force difference effect reducing torque or the behavior deterioration reducing torque A target assist torque calculating means for calculating a torque, and a control device for an electric power steering apparatus that controls the electric power steering apparatus based on the target assist torque, wherein the target assist torque calculating means When the magnitude of the force difference effect reducing torque is greater than the reference value, Electric power steering device for a control device, which comprises calculating the Sutotoruku and the target assist torque based on the sum of the longitudinal force difference impact reduction torque.   Means for calculating basic assist torque based on at least steering torque, means for calculating braking / driving force difference effect reducing torque for promoting steering in a direction to reduce the influence of braking / driving force difference between left and right wheels on the vehicle, and vehicle Means for calculating behavior deterioration reducing torque that promotes steering in a direction to reduce the oversteer state or understeer state of the vehicle, and target assist based on the basic assist torque and the braking / driving force difference effect reducing torque or the behavior deterioration reducing torque A target assist torque calculating means for calculating a torque, and a control device for an electric power steering apparatus that controls the electric power steering apparatus based on the target assist torque, wherein the target assist torque calculating means When the magnitude of the force difference effect reducing torque is greater than the reference value, The target assist torque is calculated based on the basic assist torque obtained by increasing the weight of the braking / driving force difference effect reducing torque compared to the reduced torque, the braking / driving force difference effect reducing torque, and the weight sum of the behavior deterioration reducing torque. A control device for an electric power steering device.   Means for calculating basic assist torque based on at least steering torque, means for calculating braking / driving force difference effect reducing torque for promoting steering in a direction to reduce the influence of braking / driving force difference between left and right wheels on the vehicle, and vehicle Means for calculating behavior deterioration reducing torque that promotes steering in a direction to reduce the oversteer state or understeer state of the vehicle, and target assist based on the basic assist torque and the braking / driving force difference effect reducing torque or the behavior deterioration reducing torque A target assist torque calculating means for calculating a torque, wherein the target assist torque calculating means controls the electric power steering apparatus based on the target assist torque. Torque, braking / driving force difference effect reducing torque, behavior deterioration reducing torque Electric power steering device for a control device, characterized by calculating the target assist torque based on the sum of the click.   When the magnitude of the braking / driving force difference effect reducing torque is less than a reference value, the target assist torque calculating means is configured to calculate the target assist torque based on the sum of the basic assist torque, the braking / driving force difference effect reducing torque, and the behavior deterioration reducing torque. 4. The control device for an electric power steering apparatus according to claim 1, wherein an assist torque is calculated.   5. The target assist torque calculating means limits the magnitude of the target assist torque to the upper limit reference value when the magnitude of the target assist torque exceeds an upper limit reference value. 6. Control device for electric power steering device.   6. The braking / driving force difference effect reducing torque is a torque steer reducing torque that promotes steering in a direction that cancels torque steering caused by a braking / driving force difference between left and right wheels. Control device for electric power steering device. 6. The braking / driving force difference effect reducing torque is a behavior change reducing torque that promotes steering in a direction to reduce a change in vehicle behavior caused by a braking / driving force difference between left and right wheels. The control device for an electric power steering device according to the description.

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