WO2004012977A1 - 車両の操舵装置 - Google Patents
車両の操舵装置 Download PDFInfo
- Publication number
- WO2004012977A1 WO2004012977A1 PCT/JP2003/009512 JP0309512W WO2004012977A1 WO 2004012977 A1 WO2004012977 A1 WO 2004012977A1 JP 0309512 W JP0309512 W JP 0309512W WO 2004012977 A1 WO2004012977 A1 WO 2004012977A1
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- WO
- WIPO (PCT)
- Prior art keywords
- steering
- vehicle
- value
- wheel
- lateral acceleration
- Prior art date
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/17—Using electrical or electronic regulation means to control braking
- B60T8/1755—Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
- B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
- B62D5/046—Controlling the motor
- B62D5/0463—Controlling the motor calculating assisting torque from the motor based on driver input
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
- B62D6/002—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits computing target steering angles for front or rear wheels
- B62D6/003—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits computing target steering angles for front or rear wheels in order to control vehicle yaw movement, i.e. around a vertical axis
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T2260/00—Interaction of vehicle brake system with other systems
- B60T2260/02—Active Steering, Steer-by-Wire
Definitions
- the present invention relates to a steering apparatus for a vehicle provided with a steered wheel steering mechanism that changes the steered angle of the steered wheels of the vehicle according to a steering operation performed by a driver.
- the vehicle when the vehicle turns, it is required to control the motion of the vehicle so that the turning state of the vehicle does not become unstable due to the occurrence of an excessive roll angle on the vehicle body.
- the size of the roll angle depends on the magnitude of the actual lateral acceleration which is a component of the acceleration acting on the vehicle in the lateral direction of the vehicle body, and increases with the increase of the actual lateral acceleration.
- the magnitude of the actual lateral acceleration acting on the vehicle is reduced by generating a yawing moment in the direction opposite to the turning direction of the vehicle.
- the motion control device for a vehicle disclosed in Japanese Patent Application Laid-Open No. Hei 10 1 1 9 4 3 3 rotates the vehicle according to the roll angle of the vehicle body.
- the braking force applied to each wheel is controlled to produce a yawing moment in the direction opposite to the direction.
- the braking force applied to each wheel is controlled such that the yawing moment in the direction opposite to the turning direction of the vehicle is increased according to the increase of the roll angle of the vehicle body. Therefore, when the roll angle of the vehicle body is increased, the magnitude of the lateral acceleration acting on the vehicle is reduced, and as a result, it is possible to prevent the occurrence of an excessive wheel angle on the vehicle body.
- the first feature of the present invention is that the steering angle of the steered wheels of the vehicle is changed in accordance with the steering operation operated by the driver, and the predetermined characteristic is determined in accordance with the operation power related amount of the steering by the driver.
- the steering device of a vehicle provided with a steering wheel steering mechanism that generates an assist force related amount that assists the operation of the same steering based on the characteristics of the vehicle, an excessive roll angle that indicates the degree of tendency of the vehicle to generate an excessive roll angle.
- An index value acquisition means for acquiring an occurrence tendency index value
- a steering characteristic change means for changing the predetermined characteristic according to the excessive roll angle occurrence tendency index value.
- steering refers to a lever (so-called joystick) that changes the turning angle of the steered wheels of the vehicle by translational operation, even if it is a so-called circular handle that changes the turning angle of the steered wheels of the vehicle by rotational operation. It may be present and is not limited to these.
- steering operating force related amount is, for example, an operating force (steering force) and operating torque (steering torque) when the driver operates the steering
- helping force related amount is, for example, steering The assisting force and assisting torque generated by the wheel steering mechanism are not limited to these.
- the excessive roll angle occurrence tendency index value is at least one of a lateral acceleration that is a component of the acceleration acting on the vehicle in the lateral direction of the vehicle, a roll angle generated in the vehicle, and an operation speed of steering. It is preferred that the value is based on.
- the excessive roll angle generation direction index value acquired by the index value acquisition means is a value indicating that the tendency of the vehicle to generate an excessive roll angle is large (for example, The assist force related amount generated by the steering wheel steering mechanism with respect to the same amount of steering operation force related amount by the driver can be set smaller than when the working lateral acceleration is large) and the same tendency is small.
- the driver's steering force related amount increases, the driver's It becomes difficult for the driver to make a sudden steering operation, and it is possible to prevent the turning angle of the steered wheels of the vehicle from increasing sharply in the turning direction.
- the rate of increase of the roll angle of the vehicle becomes slow, and a sufficient time for the driver to perform the steering operation in the direction of decreasing the roll angle can be secured before the increasing roll angle becomes excessive. The occurrence of an excessive roll angle on the vehicle body can be prevented.
- a steering system for a vehicle equipped with a steering wheel steering mechanism for changing a steering angle of steering wheels of the vehicle based on predetermined characteristics according to a position of steering operated by a driver.
- Index value acquiring means for acquiring an excessive roll angle occurrence tendency index value indicating the degree of tendency of the vehicle to generate an excessive roll angle; and the predetermined value according to the excessive mouth angle occurrence tendency index value.
- steering characteristic changing means for changing the characteristics of the vehicle.
- the excessive roll angle occurrence tendency index value is based on at least one of the lateral acceleration which is a component of the acceleration acting on the vehicle in the left and right direction of the vehicle body, the roll angle generated on the vehicle, and the steering speed. It is preferable that the value is
- the excessive roll angle generation direction index value acquired by the index value acquisition means is a value indicating that the tendency of the vehicle to generate an excessive roll angle is large (for example, When the lateral acceleration at work is large), when the same tendency is small, compared with the same steering position (for example, in the case of a circular steering wheel, the rotation angle from the neutral position)
- the steering angle (turning angle (deviation angle) from the reference angle at which the vehicle goes straight on) can be set small.
- the amount of increase in the turning angle of the steered wheels of the vehicle (change amount, increase speed ) Can be reduced, and in this case too, the turning angle of the same steered wheel can be prevented from rapidly increasing in the turning direction.
- the speed at which the roll angle of the vehicle body is increased slows down, and it is possible to secure a sufficient time for the driver to perform the steering operation in the direction to reduce the roll angle before the increasing roll angle becomes excessive. , Excessive on the car body It can be prevented that the roll angle occurs.
- FIG. 1 is a schematic configuration diagram of a vehicle equipped with a motion control device for a vehicle including a steering device for a vehicle according to a first embodiment of the present invention.
- FIG. 2 is a schematic configuration diagram of the steering angle tube shown in FIG.
- FIG. 3 is a schematic configuration diagram of the brake fluid pressure control device shown in FIG.
- Fig. 4 shows the value of the driver's steering torque and the steering torque used when the CPU shown in Fig. 1 calculates the assist power according to the driver's steering torque for calculating the final assist power. It is a table showing the relationship with the assist force according to the steering torque to be generated.
- Fig. 5 is a table showing the relationship between the absolute value of the actual lateral acceleration and the coefficient K t used when the CPU shown in Fig. 1 calculates the coefficient K t for calculating the final assist force. is there.
- FIG. 6 is a flowchart showing a routine for calculating the final assist force executed by the CPU shown in FIG.
- FIG. 7 is a flow chart showing a routine for calculating the wheel speed etc. executed by the CPU shown in FIG.
- FIG. 8 is a flow chart showing a routine for calculating the lateral acceleration deviation executed by the CPU shown in FIG.
- FIG. 9 is a flow chart showing a routine for the C PU to calculate the target slip ratio shown in FIG.
- FIG. 10 is a flow chart showing a routine for the CPU shown in FIG. 1 to set the control mode.
- FIG. 11 is a flowchart showing a routine for controlling the braking force applied to each wheel by the CPU shown in FIG.
- FIG. 12 is a schematic configuration diagram of a vehicle equipped with a motion control device for a vehicle including a steering device for a vehicle according to a second embodiment of the present invention.
- FIG. 13 is a schematic block diagram of the steering angle ratio variable angle chart shown in FIG. Fig.14 is a flowchart showing the routine for calculating and controlling the steering angle ratio by CPU shown in Fig.12.
- FIG. 15 is a flow chart showing a routine for calculating the roll angle by the CPU shown in FIG. 1 or FIG. BEST MODE FOR CARRYING OUT THE INVENTION
- FIG. 1 shows a schematic configuration of a vehicle equipped with a vehicle motion control device 10 including a steering device of a vehicle according to a first embodiment of the present invention.
- This vehicle is equipped with two front wheels (left front wheel FL and right front wheel FR) which are steered wheels and non-drive wheels, and two rear wheels (left rear wheel RL and right rear wheel RR) which are drive wheels. It is a four-wheel vehicle with rear wheel drive.
- the motion control device 10 of this vehicle includes a front wheel steering mechanism 20 as a steered wheel steering mechanism for steering the steered wheels FL and FR, generates a driving force and drives the driving force as a driving wheel RL. , RR, a brake fluid pressure control device 40 for generating brakes by brake fluid pressure on each wheel, a sensor portion 50 composed of various sensors, electricity And an expression controller 60.
- the front wheel steering mechanism portion 20, the sensor portion 50, and the electric control device 60 constitute a steering device of a vehicle according to an embodiment of the present invention.
- the front wheel steering mechanism portion 20 includes a circular steering wheel 21 rotationally operated by the driver, a column 22 rotatable integrally with the steering wheel 21 and extending in the longitudinal direction of the vehicle body; Column 2 2 steered by a steering lever 2 3 3, the steered steering rod 2 3 by a steering rod 24 moved in the lateral direction of the vehicle body, 4 by the same tie opening It consists of a pair of left and right links 2 51, 2 5 r that can steer the steered wheels FL, FR by movement of the gear 24.
- the steered vehicle steering wheel 23 is a so-called electric parking steering system, and as shown in FIG. 2 which is a schematic view of the steering wheel steering wheel, a rack R integrally formed with the tie rod 24 and a column 22 2 A pinion P that is integrally fixed to the front end of the vehicle body and meshes with the same rack scale, and a circular external gear coaxially integrally fixed to the middle part of the column 22 in the vehicle longitudinal direction.
- the electric motor 23 c is a tie rod in a direction to assist the driver's steering operation of the steering wheel 21 as will be described later according to the rotational torque (steering torque) of the steering wheel 21, ie, the column 22, by the driver. It generates the (final) assist force F to move 4.
- a pair of left stoppers 21 and a right stopper 24 r having a predetermined distance in the left-right direction of the vehicle body are fixed to the tie rod 24 and the movable range of the tie rod 24 in the left-right direction is fixed.
- the left end position of corresponds to the position when the right stopper 24 r abuts the right end 7 O r of the fixing member 70 fixed to the vehicle body, and the right end position of the movable range is the left stop 2 4 1 Corresponds to the position when it abuts on the left end 7 0 1 of the fixing member 70.
- the steering gear ratio ratio of the change amount of the rotation angle of the steering wheel 21 to the change amount of the steered wheel FL, FR
- the steering gear ratio in the front wheel steering mechanism portion 20 is set to a constant value “2 0”. ing.
- the driving force transmission mechanism portion 30 includes an engine 31 generating driving force, and an intake pipe 31 a of the engine 3 1, which has a throttle valve TH disposed in the intake pipe 31 a and variable in opening sectional area of the intake passage.
- a throttle valve (DC motor) 32 that controls the opening degree
- a fuel injection device 33 including an injector that injects fuel near the intake port (not shown) of the engine 31 and an output shaft of the engine 31 Transformers connected to A system 34 includes a system 34 and a differential gear 35 which appropriately distributes the driving force transmitted from the transmission 34 and transmits it to the rear wheels RR and RL.
- the brake fluid pressure control device 40 includes a high pressure generating unit 41, and a brake fluid pressure generating unit 42 for producing a brake fluid pressure corresponding to the operating force of the brake pedal BP, as shown in FIG. , FR brake fluid pressure adjusting section 43 capable of adjusting the brake fluid pressure supplied to the wheel cylinders W fr, W ⁇ , Wr r, Wr 1 respectively disposed on the respective wheels FR, FL, RR, RL An FL brake fluid pressure adjusting unit 44, an RR brake fluid pressure adjusting unit 45, and an RL brake fluid pressure adjusting unit 46 are included.
- the high pressure generating unit 41 includes an electric motor M, a hydraulic pump HP driven by the electric motor M and for boosting the brake fluid in the reservoir RS, and a check valve CVH on the discharge side of the hydraulic pump HP. And an accumulator Acc for storing the brake fluid pressurized by the hydraulic pump HP.
- the electric motor M is driven when the hydraulic pressure in the accumulator Acc falls below a predetermined lower limit, and is stopped when the hydraulic pressure in the accumulator Acc exceeds a predetermined upper limit.
- the fluid pressure in the accumulator Acc is always maintained at a high pressure within a predetermined range.
- a relief valve RV is disposed between the accumulator Acc and the reservoir RS, and when the hydraulic pressure in the accumulator Acc reaches an abnormally high pressure above the high pressure, the brake in the accumulator Acc is also disposed. Fluid is to be returned to the reservoir RS. Thus, the hydraulic circuit of the high pressure generating unit 41 is protected.
- the brake fluid pressure generating unit 42 is composed of a throttle booster HB responsive to the operation of the brake pedal BP and a master cylinder MC connected to the hydro booster HB.
- the hide port booster HB assists the operating force of the brake pedal BP at a predetermined rate using the high pressure supplied from the hydraulic high pressure generating unit 41 and transmits the assisted operating force to the master cylinder MC. It has become.
- the master cylinder MC is adapted to generate a mass evening cylinder hydraulic pressure according to the assisted operating force.
- the Hide mouth booth HB is the master cylinder fluid
- a linear hydraulic pressure corresponding to the assisted operating force which is a hydraulic pressure substantially the same as the master cylinder hydraulic pressure, is generated.
- the configuration and operation of the master cylinder MC and the hydro-booster HB are well known, so a detailed description thereof is omitted here.
- the master cylinder MC and the hydraulic booster HB generate the master cylinder hydraulic pressure and the hydraulic pressure according to the operating force of the brake pedal BP, respectively.
- Control valve SA 1 Is interspersed.
- control between the hydro booster HB and each of the upstream side of the RR brake fluid pressure adjusting unit 45 and the upstream side of the RL brake fluid pressure adjusting unit 46 is a control that is a 3-port 2-position switching type solenoid valve.
- Valve SA 2 is installed.
- a switching valve STR which is a two-point two-position switching type normally closed electromagnetic on-off valve, is interposed between the high pressure generating unit 41 and each of the control valve SA1 and the control valve SA2. .
- control valve SA 1 When control valve SA 1 is in the first position (position in the non-excitation state) shown in FIG. 3, master cylinder MC, the upstream portion of FR brake fluid pressure adjustment unit 43, and FL brake fluid pressure adjustment unit 44 When communicating with each of the upstream parts and in the second position (the position in the excited state), the master cylinder MC, the upstream part of the FR brake fluid pressure adjusting part 43 and the FL brake fluid pressure adjusting part 44 Communication with each of the upstream portions is shut off to connect the switching valve STR with each of the upstream portion of the FR brake fluid pressure adjusting portion 43 and the upstream portion of the FL brake fluid pressure adjusting portion 44.
- the upstream portion of the hydro booster HB and the RR brake fluid pressure adjustment unit 45 and the RL brake fluid pressure adjustment unit 46 When communicating with each of the upstream parts and in the second position (position in the excited state), the hydrobooster HB and the RR brake fluid pressure adjusting section 45 have an upstream section and an RL brake fluid pressure adjusting section 46 Communication with each of the upstream portions is shut off to connect the switching valve STR with each of the upstream portion of the RR brake fluid pressure adjusting portion 45 and the upstream portion of the RL brake fluid pressure adjusting portion 46.
- the control valve SA2 when the control valve SA2 is in the first position, the regulated return fluid pressure is supplied to the upstream portion of the RR brake fluid pressure adjusting portion 45 and the upstream portion of the RL brake fluid pressure adjusting portion 46.
- the high pressure generated by the high pressure generator 41 is supplied when the control valve SA 2 is in the second position and the switching valve STR is in the second position.
- the FR brake fluid pressure adjustment unit 43 is composed of a pressure increasing valve PUfr, which is a two-port two-position normally open solenoid valve, and a pressure reducing valve PDfr which is a two-port two-position normally closed solenoid open valve.
- PUfr pressure increasing valve
- PDfr pressure reducing valve
- the brake fluid pressure in the wheel cylinder Wfr is supplied with the fluid pressure in the upstream portion of the FR brake fluid pressure adjusting portion 43 in the wheel cylinder Wfr when both the pressure increasing valve PUfr and the pressure reducing valve PDfr are in the first position.
- the pressure increasing valve PUfr is in the second position and the pressure reducing valve PDfr is in the first position, the fluid at the point in time regardless of the fluid pressure in the upstream portion of the FR brake fluid pressure adjusting portion 43
- the pressure is maintained and the brake fluid in the wheel cylinder Wfr is reduced by being returned to the reservoir RS when both the pressure increasing valve PUfr and the pressure reducing valve PDfr are in the second position.
- a check valve CV 1 that allows only one-way flow of brake fluid from the wheel cylinder Wfr side to the upstream part of the FR brake fluid pressure adjustment unit 43 is arranged in parallel to the pressure intensifying valve PUfr.
- the control valve SA 1 is operated in the first position. The brake fluid pressure in the wheel cylinder Wfr is quickly reduced when the brake pedal BP being operated is released.
- the FL brake fluid pressure adjustment unit 44, the RR brake fluid pressure adjustment unit 45, and the RL brake fluid pressure adjustment unit 46 respectively include a pressure increasing valve PUfl and a pressure reducing valve PDfl, a pressure increasing valve PU rr and a pressure reducing valve PDrr, It consists of pressure valve P Url and pressure reducing valve P Drl, and by controlling the position of each pressure increasing valve and each pressure reducing valve, the brake fluid in wheel cylinder Wfl, wheel cylinder Wrr and wheel cylinder Wrl The pressure can be increased, maintained and reduced respectively.
- check valves CV2, CV3 and CV4 capable of achieving the same function as the check valve CV1 are respectively arranged in parallel to the pressure increasing valves PUfl, PUrr and PUrl.
- a check valve CV5 that allows only one flow of brake fluid from the upstream side to the downstream side is arranged in parallel in the control valve SA1, and the control valve SA1 is in the second position.
- wheel cylinder Wfr is operated by operating brake pedal BP.
- Wf 1 can now be boosted.
- a check valve CV6 that can achieve the same function as the check valve CV5 is disposed in parallel.
- the brake fluid pressure control device 40 can supply the brake fluid pressure corresponding to the operating force of the brake pedal BP to each wheel cylinder when all the solenoid valves are in the first position. There is. Further, in this state, for example, by controlling the pressure increasing valve PUrr and the pressure reducing valve PDrr, respectively, only the brake fluid pressure in the wheel cylinder Wrr can be reduced by a predetermined amount.
- the brake fluid pressure control device 40 sets, for example, both the control valve SA1, the changeover valve STR and the pressure intensifying valve PUfl to the second position when the brake pedal BP is not operated (opened).
- the brake fluid in the wheel cylinder Wfr is utilized by using the high pressure generated by the high pressure generator 41 while holding the brake fluid pressure in the wheel cylinder Wfl. Only the pressure can be increased by a predetermined amount.
- the brake fluid pressure control device 40 independently controls the brake fluid pressure in the wheel cylinder of each wheel independently of the operation of the brake pedal BP, and independently for each wheel It is possible to apply a predetermined braking force. Referring again to FIG.
- the sensor unit 50 has a signal having a pulse each time the wheels FL, FR, RL and RR rotate by a predetermined angle.
- the wheel speed sensor 5 1 fl, 5 1 fr, 5 1 rl and 5 1 rr consisting of a single output tally encoder and the rotation angle from the neutral position of the steering 2 1 are detected, and the steering angle 0
- the steering angle sensor 52 as a steering angle acquisition means that outputs a signal indicating s and the operation amount of the accelerator pedal AP operated by the driver are detected, and a signal indicating the operation amount Accp of the accelerator pedal AP is output.
- an accelerator opening sensor 5 3 detects a lateral acceleration a lateral direction of the vehicle body component of the actual acceleration acting on the vehicle (excessive roll generating tendency index value), a signal showing lateral acceleration Gy (m / s 2)
- a lateral acceleration sensor 54 as an index value acquisition means for outputting a signal
- a brake switch 55 for detecting whether or not the brake pedal BP is operated by the driver and outputting a signal indicating the presence or absence of the brake operation; It detects the height from the road surface of each specific part of the vehicle body in the vicinity of the wheels FL, FR, RL and RR, and outputs a signal indicating the vehicle height, Hfr, Hrl and Hrr of each wheel.
- the value of the steering angle 0 s is “0” when the steering 2 1 is in the neutral position, and is positive when the steering 2 1 is rotated counterclockwise (as viewed from the driver) from the neutral position.
- the value is set to be a negative value when the steering 21 is rotated clockwise from the neutral position.
- the value of the lateral acceleration Gy is set to be a positive value when the vehicle is turning to the left and a negative value when the vehicle is turning to the right.
- the value of the steering torque T is a positive value when the driver rotates the steering 2 1 to the left (in the counterclockwise direction when viewed from the driver), the driver rotates the steering 2 1 to the right (driving It is set to be a negative value when rotating it in the direction of the clock rotation as seen from the user.
- the electric control unit 60 requires the CPU 61 connected via a bus, a routine (program) executed by the CPU 61, a table (look-up table, map), a ROM 62 in which constants and the like are stored in advance, and the CPU 61
- RAM 63 temporarily stores data
- backup RAM 64 which stores data while power is on and keeps the stored data while power is off
- AD It is a microcomputer comprising an interface 65 and the like including a converter.
- the interface 65 is connected to the sensors 51 to 57, supplies signals from the sensors 51 to 57 to the CPU 61, and according to the instruction from the CPU 61, the front wheel steering mechanism unit 20
- the drive signal is sent to the electric motor 23 c, the solenoid valves of the brake fluid pressure control device 40 and the motor M, the throttle valve 32, and the fuel injection device 33.
- the electric motor 23c generates a predetermined assist force
- the throttle valve valve 32 is controlled so that the throttle valve TH has an opening degree corresponding to the operation amount Accp of the accelerator pedal AP.
- the fuel injection device 33 sets a predetermined target air-fuel ratio with respect to the amount of intake air corresponding to the opening degree of the throttle valve TH.
- the steering apparatus for a vehicle has a relationship (predetermined characteristic) between the value of the driver's steering torque T and the assist force F1 to be generated by the electric motor 23c in FIG. 2 according to the value of the steering torque T. Based on the table shown in FIG. 4 that represents, the assist gear F1 corresponding to the steering torque T is calculated according to the predetermined characteristic.
- the absolute value of the assist force F1 corresponding to the steering torque T is calculated to increase according to the increase of the absolute value of the steering torque T.
- fast steering torque F1 has a positive value, which causes the steered wheels FL and FR to be set. It becomes a force in the direction of turning to the left.
- the steering torque T is a negative value (when the driver rotates the steering wheel 21 clockwise when viewed from the driver), the value is negative, and this causes the steered wheels FL and FR to turn to the right. Become a force of direction.
- the assist force F1 is an assisting force for assisting the driver's steering operation.
- the present apparatus calculates the absolute value of the actual lateral acceleration Gy acting on the vehicle obtained by the lateral acceleration sensor 54 as the excessive roll angle tendency index value, the absolute value of the actual lateral acceleration Gy, and the coefficient K
- the coefficient K t is calculated based on the table shown in FIG. 5 which shows the relationship with t.
- the coefficient K t changes from the assist force F 1 according to the absolute value of the actual lateral acceleration Gy (predetermined It is a coefficient for changing the characteristic).
- the coefficient K t is set to a constant value “1” when the absolute value of the actual lateral acceleration Gy is less than the value Gy th, and the absolute value of the actual lateral acceleration Gy is the value Gyth
- the absolute value of the actual lateral acceleration Gy is set to be a positive value and to decrease linearly from "1" as it increases from the value Gyth. Then, the present device calculates the final assist force F based on the following equation (1).
- the value of the final assist force F K t-F 1 ⁇ ⁇ ⁇ (1) Therefore, when the absolute value of the actual lateral acceleration Gy is less than the value Gyth, the value of the final assist force F is the value of the assist force F 1 according to the steering torque T When the absolute value of the actual lateral acceleration Gy is equal to or more than the value Gyth, the absolute value of the final assist force F becomes the absolute value of the assist force F 1 as the absolute value of the actual lateral acceleration Gy increases from the value Gyth. It is set to be smaller than the value. In other words, the above-mentioned predetermined characteristic is not changed when the excessive mouth angle tendency index value (absolute value of the actual lateral acceleration Gy) is less than the predetermined value (value Gyth), and the excessive mouth angle tendency is generated. When the index value is equal to or more than the predetermined value, it is changed according to the increase of the excessive roll angle tendency index value.
- the present device drives the electric motor 23 c so that the electric motor 23 c of FIG. 2 generates the final assist force F set as described above, and as a result, the final assist force F The driver's steering operation is assisted.
- the motion control device 10 for a vehicle including the present device is a target lateral acceleration Gyt (m / s 2 ) based on the following equation (2) which is a theoretical equation as a predetermined rule derived from the motion model of the vehicle.
- the target lateral acceleration Gyt is a positive value when the vehicle is turning to the left (when the steering angle 0 s (deg) is a positive value), and the vehicle is turning to the right. It is set to be a negative value (when the steering angle has a negative value).
- This theoretical expression is an expression for calculating the theoretical value of the lateral acceleration acting on the vehicle when the vehicle turns (at the time of steady circular turning) with both the steering angle and the vehicle speed being constant.
- Gyt (Vso 2- s s) / (nl)-(l / (l + Kh-Vso 2 )) ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ (2)
- Vso is calculated as will be described later. It is speed (m / s).
- n is a steering gear ratio (in this example, a constant value “2 0”), which is a ratio of the change amount of the turning angle of the steering wheel 21 to the change amount of the turning angle of the steered wheels FL and FR.
- m wheelbase
- Kh is the stability factor (s 2 / m 2 ), which is a fixed value determined by the vehicle body.
- the motion control device 10 for a vehicle including the present device is actually obtained by the absolute value of the target lateral acceleration Gy t calculated as described above based on the following equation (3) and the lateral acceleration sensor 54.
- the vehicle motion control device 10 controls the under-steer suppression control to suppress the under-steer state. Run. Specifically, the motion control device 10 generates a predetermined braking force corresponding to the value of the lateral acceleration deviation AGy on the inner rear wheel in the turning direction, and applies a braking force in the same direction as the turning direction to the vehicle. Force the swing moment. As a result, the absolute value of the actual lateral acceleration Gy increases, and the actual lateral acceleration Gy is controlled so as to approach the target lateral acceleration Gyt.
- the vehicle has a target lateral acceleration Gyt It is in a state where the turning radius is smaller than the turning radius assuming that it occurs in the same vehicle (hereinafter referred to as "over-steer state"), and further, the actual lateral acceleration acting on the vehicle Since the absolute value of Gy is a large value, the roll angle generated on the vehicle body is also large. At this time, the motion control device 10 of the vehicle executes over-steer suppression control to suppress the bar-steer state.
- the motion control device 10 generates a predetermined braking force corresponding to the value of the lateral acceleration deviation A Gy on the front wheel on the outside in the turning direction, and the motor control device 10 generates a braking force in the opposite direction to the turning direction. Force a message.
- the absolute value of the actual lateral acceleration Gy decreases and the actual lateral acceleration Gy is controlled to approach the target lateral acceleration Gyt, and the roll angle generated on the vehicle body decreases, and the excessive roll angle It is prevented from occurring.
- the vehicle motion control device 10 is assigned to each wheel.
- a predetermined yawing moment is generated for the vehicle in the direction in which the actual lateral acceleration Gy approaches the target lateral acceleration Gyt calculated as described above.
- the brake force to be applied to each wheel is determined in consideration of the brake force to be applied to each wheel in order to execute any one control.
- the routine executed by the CPU 61 of the electric control device 60 is actually executed regarding the actual operation of the vehicle movement control device 10 including the steering device of the vehicle according to the present invention configured as described above.
- “**” attached at the end of various variables' flags and signs etc. is used to indicate which of the wheels FR etc. the same variable 'flags' sign etc. relate to.
- the wheel speed VwW is: front left wheel speed Vwfl, front right wheel speed Vwfr, rear left wheel speed Vwr l right
- the rear wheel speed Vwrr is shown comprehensively.
- C PU 61 repeatedly executes the routine for calculating the assist force and applying the assist force shown in FIG. 6 at predetermined time intervals. Therefore, when the predetermined timing is reached, the CPU 61 starts processing from step 600, proceeds to step 600, and obtains the driver's steering torque T value obtained by the torque sensor 57; Based on the table shown in and the table described in step 605, which is the same table, the assist force F1 corresponding to the steering torque T is calculated.
- step 610 the absolute value of the actual lateral acceleration Gy obtained by the lateral acceleration sensor 54 and the same table as the table shown in FIG.
- the coefficient K t is calculated based on the table described in the following, and the process proceeds to the subsequent step 6 15 and the value of the assist force F 1 calculated in the step 6 0 5 and the coefficient calculated in the step 6 10
- the final assist force F is calculated based on the value of K t and the equation described in step 6 15 based on the right side of the equation (1).
- step 615 corresponds to the steering characteristic changing means.
- the CPU 61 proceeds to step 620, and the driving force of the electric motor 23c is output so that the electric motor 23c generates the final assist force F calculated in step 650.
- the CPU 61 has a duty ratio according to the absolute value of the final assistor F and a duty signal in which the sign of the final assist cover F is taken into consideration.
- the electric motor 23c is controlled by outputting it to a drive circuit (not shown) c and the electric current corresponding to the duty signal is output to the electric motor 23c. Then, the CPU 61 proceeds to step 695 to end this routine once.
- the final assist force F assists the driver's steering operation. Next, the calculation of the wheel speed and the like will be described.
- the CPU 61 repeatedly executes the routine shown in FIG. 7 every predetermined time. Therefore, at a predetermined timing, the CPU 61 starts the process from step 700, proceeds to step 750, and calculates the wheel speeds of the wheels FR and the like (the speed of the outer periphery of each wheel). Specifically, the CPU 61 calculates the wheel speeds Vw ** of the respective wheels FR and the like based on the time intervals of the pulses possessed by the signals outputted by the respective wheel speed sensors 5 1. Next, the CPU 61 proceeds to step 710 and calculates the maximum value of the wheel speeds Vw ** of the wheels FR etc. as the estimated vehicle speed Vso. The average value of the wheel speeds Vw ** of the respective wheels FR etc. may be calculated as the estimated vehicle speed Vso.
- Step 710 corresponds to vehicle speed acquisition means.
- Step 7 Calculate the actual slip ratio Sa «for each wheel based on the equation described in step 7 15. This actual slip ratio Saw is used in calculating the braking force to be applied to each wheel, as described later.
- C PU 61 proceeds to step 720 to calculate an estimated vehicle body acceleration DVso which is a time derivative value of the estimated vehicle body speed Vso based on the following equation (4).
- Vsol is the previous estimated vehicle speed calculated in step 710 at the previous execution of this routine
- a t is this It is the above-mentioned predetermined time which is the operation cycle of the routine. Then, the CPU 61 proceeds to step 795 to end this routine once.
- C PU 61 repeatedly executes the routine shown in FIG. 8 at predetermined time intervals. Therefore, at the predetermined timing, the CPU 61 starts the process from step 800, proceeds to step 800, and obtains the value of the steering angle 0 s obtained by the steering angle sensor 52, and the step of FIG.
- the target lateral acceleration Gyt is calculated based on the value of the estimated vehicle speed Vso calculated in 7 10 and the equation described in the step 800 corresponding to the right side of the equation (2).
- step 800 corresponds to the target lateral acceleration calculating means.
- step 810 the value of the target lateral acceleration Gyt calculated in step 800, the value of the actual lateral acceleration Gy obtained by the lateral acceleration sensor 54, and the above (3
- the lateral acceleration deviation A Gy is calculated based on the equation described in step 810 corresponding to the right side of the equation). Then, the CPU 6 1 proceeds to step 8 9 5 Stop once.
- the CPU 61 starts processing from step 900, proceeds to step 950, and the value of the actual lateral acceleration Gy obtained by the lateral acceleration sensor 54 is "0". If the actual value of lateral acceleration Gy is "0" or more, it is judged as "Y es" in the same step 905, and the process proceeds to step 990. Set the turn direction indicator flag L to "1". If the actual value of lateral acceleration Gy is a negative value, it is judged as "No" at the same step 905 and the process proceeds to step 915, and the turning direction display flag L is set to "0". Set to
- the turning direction display flag L is a flag indicating whether the vehicle is turning leftward or turning rightward, and when the value is “1”, the vehicle is turning leftward. Indicates that the vehicle is turning to the right when the value is “0”. Therefore, the turning direction of the vehicle is specified by the value of the turning direction display flag L.
- step 960 the CPU 61 proceeds to step 960 and performs brake steering control based on the absolute value of the lateral acceleration deviation A Gy calculated in step 810 of FIG. 8 and the table described in step 960.
- Step 9 As shown in the table in 2 0, the control amount G is set to “0” when the absolute value of the lateral acceleration deviation A Gy is less than the value Gyl, and the absolute value of the lateral acceleration deviation A Gy is When the value is greater than value Gyl and less than value Gy2, the absolute value of the same lateral acceleration deviation A Gy linearly changes from "0" to a constant positive value G 1 as it changes from value Gyl to value Gy2.
- the CPU 61 determines that the vehicle is understeer as described above, and performs each of the above-described understeer suppression control. In order to calculate the target slip ratio of the wheel, the process proceeds to step 930, and it is determined whether or not the value of the turning direction indication flag L is "1".
- step 930 When it is determined in step 930 that the turning direction display flag L is “1”, the CPU 6 proceeds to step 935 to use the positive constant value Kr and the value of the control amount G calculated in step 920 for the coefficient Kr. Set the multiplied value as the target slip ratio Strl for the left rear wheel RL, and set the target slip ratios Stfl, Stfr, Strr for all the other wheels FL, FR, RR to "0", and go to step 995 End this routine once. As a result, the target slip ratio corresponding to the absolute value of the lateral acceleration deviation AGy is set only for the left rear wheel RL corresponding to the inner rear wheel in the turning direction when the vehicle is turning to the left.
- step 930 when it is determined in step 930 that the turning direction display flag is “0”, the CPU 6 proceeds to step 940 and multiplies the coefficient Kr by the value of the control amount G calculated in step 920 and The target slip ratio Strr for the rear wheel RR is set, and the target slip ratios Stfl, Stfr and Strl for the other wheels FL, FR and RL are all set to “0”, and the process proceeds to step 995 to temporarily execute this routine. finish. More this, a target slip rate corresponding to the absolute value of the lateral acceleration deviation AGy only the right rear wheel RR which is the rear wheel turning inward when the vehicle is turning to the right direction is set: Ru.
- step 925 if it is determined in step 925 that the value of the lateral acceleration deviation AGy is a negative value, the CPU 61 determines that the vehicle is in the over one steering state as described above, and the over one steering suppression is performed. In order to calculate the target slip ratio of each wheel at the time of execution of control, the process proceeds to step 945, and it is determined whether or not the value of the turning direction indicator flag L is "1".
- step 945 When it is determined in step 945 that the turning direction indication flag is “1”, the CPU 6 proceeds to step 950 to step 920 to a coefficient Kf which is a positive constant value.
- the target slip ratio Stfr of the right front wheel FR is set as the value obtained by multiplying the value of the control amount G calculated in the above, as the target slip ratio Stfr for the other wheels FL, RL, RR. Set to 0 "and proceed to step 995 to end this routine once.
- the target slip ratio corresponding to the absolute value of the lateral acceleration deviation AGy is set only for the right front wheel FR corresponding to the front wheel on the outside in the turning direction when the vehicle is turning to the left. ⁇
- step 945 the CPU 66 proceeds to step 955 and multiplies the coefficient Kf by the value of the control amount G calculated in step 920.
- the target slip ratio Stfl of the left front wheel FL and the target slip ratios Stfr, Strl, Strr of the other wheels FR, RL, RR are all set to "0", and the process proceeds to step 995 to execute this routine. It will end once.
- a target slip ratio corresponding to the absolute value of the lateral acceleration deviation AGy is set only for the left front wheel FL corresponding to the front wheel on the outside in the turning direction when the vehicle is turning right.
- the target slip ratio of each wheel necessary to determine the braking force to be applied to each wheel when executing only the braking steering control is determined.
- the CPU 61 repeatedly executes the routine shown in FIG. 10 every predetermined time. Therefore, when the predetermined timing is reached, the CPU 66 starts processing from step 1000, proceeds to step 1005, and determines whether anti-skid control is required at this time.
- Anti-skid control is control to reduce the braking force of a specific wheel when the specific wheel is locked while the brake pedal BP is operated. The details of anti-skid control are well known, so the detailed description is omitted here.
- CPU 61 is the case where it is shown that brake switch BP is operated by brake switch 55 in step 1005, and it is calculated in step 7 15 of FIG. It is determined that anti-skid control is required if the actual slip ratio Sa ** of a particular wheel is greater than or equal to a positive predetermined value.
- step 1 0 1 0 sets the variable Mode to “1” to set a control mode in which the brake steering control and the anti-skid control are superimposed and executed, and the following steps 1 0 5 Go to 0.
- step 1005 when it is determined in step 1005 that anti-skid control is not necessary, the CPU 61 proceeds to step 105 to determine whether the front / rear braking force distribution control is necessary at this time. Determine if The front and rear braking force distribution control is a control that reduces the ratio (distribution) of the rear wheel braking force to the front wheel braking force according to the degree of deceleration of the vehicle while the brake pedal BP is operated. It is. The details of the front and rear braking force distribution control are well known, so the detailed description is omitted here.
- the CPU 61 is in the case where it is shown that the brake pedal BP is operated by the brake switch 5 5 in the step 1 0 15, and in the step 7 2 0 of FIG. If the value of the estimated vehicle body acceleration DVso calculated is negative and the absolute value of the estimated vehicle body acceleration DVso is greater than or equal to a predetermined value, it is determined that front and rear braking force distribution control is necessary.
- step 1 0 1 5 When it is determined in step 1 0 1 5 that front and rear braking force distribution control is necessary, the CPU 61 proceeds to step 1 0 2 0 and superimposes brake steering control and front and rear braking force distribution control. Set “2” to the variable Mode to set the control mode to be executed and continue
- the CP U 61 proceeds to step 1005 to determine whether or not the trajectory control is necessary at the present time.
- the traction control is a control that increases the braking force of a specific wheel when the specific wheel is spinning in the direction in which the driving force of the engine 31 is generated when the brake pedal BP is not operated. Or it is control to reduce the driving force of the engine 31.
- the details of the trajectory control are well known, so the detailed description is omitted here.
- CPU 61 is in the case where it is indicated in step 10 25 that the brake pedal BP is not operated by the brake switch 5 5, and in step 7 15 of FIG. 7. Calculated actual slip ratio of a particular wheel Sa ** If the value is a negative value and the absolute value of the actual slip ratio Sa ** is greater than or equal to a predetermined value, it is determined that lubrication control is necessary.
- step 1030 the CPU 61 proceeds to step 1030 to set a control mode in which the brake steering control and the trajectory control are superimposed and executed. Set Mode to "3" and proceed to step 1 050.
- step 1035 determines whether the above-described brake steering control is necessary at the present time. Specifically, in step 1035, the CPU 61 determines that the absolute value of the lateral acceleration deviation AGy calculated in step 810 in FIG. 8 is greater than or equal to the value Gyl in the table described in step 920 in FIG. If it is, it is determined that the brake steering control is necessary because there is a specific wheel for which the value of the target slip ratio StOther set in FIG. 9 is not “0”.
- step 1035 If it is determined at step 1035 that the brake steering control is necessary, the CP U 61 proceeds to step 1040 and sets the variable Mode to “4” to set the control mode to execute only the brake steering control. Set and proceed to the next step 1050.
- step 1040 sets the variable Mode to “4” to set the control mode to execute only the brake steering control. Set and proceed to the next step 1050.
- step 1 03 5 the brake steering control is not necessary
- the CPU 6 1 proceeds to step 1 045 to set the variable Mode “to set the non-control mode not to execute the vehicle motion control. Set “0” and proceed to the next step 1050. In this case there is no specific wheel to control.
- the wheel to be controlled in this step 1050 is a wheel that needs to control at least one of the corresponding pressure increasing valve and pressure reducing valve PD shown in FIG.
- the brake fluid pressure in the wheel cylinder Wfr can be controlled using the high pressure generated by the high pressure generator 41 while holding the brake fluid pressure in the wheel cylinder W. It will increase pressure. Therefore, the wheel to be controlled in this case includes not only the right front wheel FR but also the left front wheel FL. Then, after executing step 1 0 5 0, the CPU 6 1 proceeds to step 1 0 5 5 to temporarily end this routine. In this way, the control mode is identified and the wheel to be controlled is identified.
- C PU 61 repeatedly executes the routine shown in FIG. 11 every predetermined time. Therefore, when the predetermined timing comes, the CPU 61 starts processing from step 1 1 0 0 and proceeds to step 1 1 0 5 to determine whether or not the variable Mode is not "0". If it is “0”, it is judged “No” at step 1 1 0 5 and the process proceeds to step 1 1 1 0, and since it is not necessary to execute brake control for each wheel, the brake fluid pressure control device 40 After all the solenoid valves are turned off (non-excitation state), the process proceeds to step 1195 and the routine is temporarily ended. As a result, the brake fluid pressure corresponding to the operating force of the brake pedal BP by the driver is supplied to each wheel cylinder W.
- step 1 1 2 determines “0” in the determination of step 1 0 5 if the variable Mode is not “0” in the determination of step 1 0 5, the CPU 6 1 determines “Y es” in step 1 1 0 5 and proceeds to step 1 1 1 5 and the variable Mode is “4 It is determined whether or not If the variable Mode is not "4" (ie, anti-skid control other than brake steering control is required), the CPU 61 determines "No” at step 1 1 5 and step 1 Proceed to step 120.
- the brake steering control already set in FIG. 9 is executed on the control target wheel for which the value of the flag C0NT is set to “1” in step 1005 in FIG. After correcting the target slip ratio S i of each wheel, which is necessary for the process, proceed to step 1 1 2 5.
- the target slip ratio S t of each wheel already set in FIG. 9 is equal to the target slip ratio of each wheel, which is necessary when performing control corresponding to the value of the variable Mode superimposed on the brake steering control. It is corrected for each control target wheel.
- step 1 1 1 5 determines “Y es”, and it is not necessary to correct the target slip ratio St «of each wheel already set in FIG. 9, so it proceeds directly to step 1 1 2 5.
- the CPU 61 proceeds to step 1 125, the value of the target slip ratio St for the control target wheel whose flag value is set to “1” in step 1 0 5 0 of FIG.
- the slip ratio deviation AS t « is calculated for each control target wheel based on the value of the actual slip ratio Sa « calculated in step 7 1 5 of FIG. 7 and the equation described in step 1 1 2 5
- the CPU 61 proceeds to step 1130 to set a fluid pressure control mode for each wheel to be controlled with respect to the wheel to be controlled.
- the CPU 61 uses the slip ratio deviation A St Other value for each controlled object wheel calculated in step 1 125 and the table described in step 1 130.
- the fluid pressure control mode is set to “pressure increase”, and the value of slip ratio deviation A St «is a predetermined negative reference.
- the fluid pressure control mode is set to “Hold” when it is above the predetermined value and below the predetermined positive reference value, and when the value of the slip ratio deviation ⁇ S t is below the predetermined negative reference value, the fluid Set pressure control mode to "depressurize”.
- the CPU 61 proceeds to step 1 1 35 and based on the hydraulic pressure control mode for each control target wheel set in step 1 1 3 0, the control valves SA 1, SA 2 shown in FIG. It controls the switching valve STR and controls the pressure increasing valve and pressure reducing valve PD according to the same fluid pressure control mode for each wheel to be controlled.
- the CPU 61 controls both the pressure increasing valve and the pressure reducing valve PD at the first position (position in the non-excitation state). Control the pressure control valve to the second position (position in the excited state) and control the corresponding pressure reducing valve to the first position.
- the corresponding pressure increasing valve PU and pressure reducing valve are both controlled to the second position (position in the excited state).
- step 1 1 3 5 corresponds to the braking force control means.
- the CPU 61 makes the throttle valve TH open by a predetermined amount smaller than the opening corresponding to the operation amount Accp of the accelerator pedal AP, if necessary. Control the throttle valve and so on. Then, the CPU 6 proceeds to step 1 195 to end this routine once.
- the (final) assist force F for the same steering torque T by the driver is set smaller as the actual value of the lateral acceleration Gy increases compared to when the actual value of the lateral acceleration Gy is below the value Gyth. Be done. Therefore, when the steering torque T at which the driver operates the steering wheel 2 becomes large, it becomes difficult for the driver to perform the rapid steering operation itself, and the steering angles of the steered wheels FL and FR of the vehicle turn Sudden increase in direction is prevented.
- the lateral acceleration which is a value obtained by subtracting the absolute value of the actual lateral acceleration Gy from the absolute value of the target lateral acceleration Gyt of the vehicle calculated based on the above equation (2) which is a theoretical expression derived from the motion model of the vehicle.
- the value of the deviation A Gy is a negative value, that is, when the absolute value of the actual lateral acceleration Gy acting on the vehicle is large and the roll angle generated on the vehicle body is also large, the turning direction by the bar steer suppression control.
- a braking force corresponding to the value of the lateral acceleration deviation A Gy is generated on the outer front wheel to forcibly generate a yawing moment in the direction opposite to the turning direction of the vehicle.
- the actual lateral acceleration Gy is While the pair value becomes smaller and the actual lateral acceleration Gy is controlled to approach the target lateral acceleration Gy t, the roll angle generated on the vehicle body is reduced and the occurrence of an excessive roll angle on the vehicle body is prevented .
- the occurrence of an excessive roll angle on the vehicle body is more reliably prevented.
- FIG. 12 shows a schematic configuration of a vehicle equipped with a motion control device 10 for a vehicle including a steering device for a vehicle according to a second embodiment of the present invention.
- the difference in mechanical configuration of the second embodiment shown in FIG. 12 with respect to the first embodiment shown in FIG. 1 is that the sensor unit 50 detects the turning angles of the steered wheels FL, FR, A steering angle sensor 5 8 is added to output a signal indicating steering angle ⁇ s s to the interface 6 5 of the electric control device 60, and a middle portion of the column 2 2 in the longitudinal direction of the vehicle (FIG. 2 This is the point where the steering angle ratio variable interface 26 is interposed in the middle of the rear part of the vehicle from the circular external gear 23a.
- the sensor unit 50 detects the turning angles of the steered wheels FL, FR
- a steering angle sensor 5 8 is added to output a signal indicating steering angle ⁇ s s to the interface 6 5 of the electric control device 60, and a middle portion of the column 2 2 in the longitudinal direction of the vehicle (FIG. 2 This is the point where the steering angle ratio variable interface 26 is interposed in the middle of the rear part of the vehicle from the circular external gear 23a.
- variable steering ratio control 26 Since the steering angle ratio variable control 26 is interposed in the column 22, one end of the column 22 is integrally fixed to the steering 21, and the other end is variable steering ratio control 26 6 Column rear part 2 2 a connected to it, Column front part 2 2 b with one end connected to variable steering ratio variable 26 and the other end connected to steered angle part 2 3 It is divided into
- the steering angle sensor 5 8 detects the rotation angle of the column front portion 2 2 b to change the steering wheel FL, FR steering angle of the steered wheels FL, FR in accordance with the rotation angle of the column front portion 2 2 b. It is designed to detect S ss.
- the steered angle of the steered wheels FL, FR 0 ss is “0” when the steered angle of the steered wheels FL, FR is at the reference angle at which the vehicle travels straight, and the steered angle of the steered wheels FL, FR is the reference angle
- the steered wheels FL, FR are steered to the left from the state in, a positive value is obtained. From the state where the steered angle of the steered wheels FL, FR is at the reference angle It is set to have a negative value when it is steered.
- a sun gear 26a integrally connected to the rear portion 22a of the core, and a sun gear 26a of the same.
- a carrier 26c configured to be integrally rotatable with the portion 22b, and a sun gear 26a that rotates concentrically and is disposed at the radially outer position of the plurality of planetary gears 26b, and the plurality of planets
- the ring gear 2 6 d that meshes with the gear 2 6 b, and the so-called star gear mechanism including.
- the steering angle ratio variable actuator 26 is equipped with an electric motor 26 e.
- a worm gear 26f is fixed on the output shaft of the electric motor 26e, and the worm gear 26 is a worm (not shown) integrally provided on the outer peripheral surface of the ring gear 26d. It meshes with the wheel gear.
- the interface 65 of the electric control device 60 sends a drive signal to the electric motor 26 e in accordance with the instruction of C PU 61.
- the (rotational) position of the ring gear 2 6 is set to the neutral position (detent torque) by the holding torque (detent torque).
- the steering angle 0 s is “0”, it is possible to fix the steering wheel FL, FR at a position where the steered angle 0 ss becomes “0”.
- the rotation angle of the ring gear 26 d from the neutral position is changed to the value “2 0”.
- the steering angle ratio n is to be changed accordingly .
- the CPU 61 can control the rotation angle of the ring gear 26 d from the neutral position by driving the electric motor 26 e.
- the routine executed by the CPU 61 will be described with reference to a chart.
- the CPU 61 performs a routine for calculating and controlling the steering angle ratio n shown in FIG. It is repeatedly executed each time the
- the CPU 61 starts the process from step 140 and proceeds to step 1405.
- the absolute value of the actual lateral acceleration Gy obtained by the lateral acceleration sensor 54, and the step The steering angle ratio n is calculated based on the table described in 1405.
- the steering angle ratio n is set such that the absolute value of the actual lateral acceleration Gy becomes a fixed value "2 0" when the absolute value of the actual lateral acceleration Gy is less than the value Gyth, and the absolute value of the actual lateral acceleration Gy is greater than the value Gyth
- the absolute value of the same actual lateral acceleration Gy is set to increase linearly from “2 0” as it increases from the value Gyth.
- the steering angle ratio n predetermined characteristic
- the steering angle ratio n is not changed when the excessive roll angle tendency index value (the absolute value of the actual lateral acceleration Gy) is less than or equal to the predetermined value (value Gyth).
- the trend index value is equal to or greater than the predetermined value, the value is changed in accordance with the increase in the excessive roll angle tendency index value.
- step 1405 corresponds to the steering characteristic changing means.
- the CPU 61 proceeds to step 1140 to control the electric motor 26e so that the actual steering angle ratio becomes equal to the steering angle ratio n calculated in step 1405.
- the CPU 61 obtains the value of the steering angle s s at the present time by the steering angle sensor 52, and the turning angles of the steered wheels FL, FR at the present time ss by the turning angle sensor 58.
- the process proceeds to step 1 495 to end this routine once.
- the steered wheel FL, FR turning angle 0 ss for the same steering rotation angle 0 s as the actual value of the acceleration Gy becomes equal to or less than the value Gyth according to the increase of the actual value of the same lateral acceleration Gy It is set small.
- the amount of increase (change amount, increase speed (change speed)) of the turning angle 0 ss of the turning direction of the vehicle steering wheels FL and FR is The FL and FR steered angles of the steered wheels increase sharply in the turning direction, combined with the effect of the control according to the actual lateral acceleration Gy of the final assist vehicle F described in the first embodiment. Is further prevented. As a result, the rate of increase of the roll angle of the vehicle body is slowed, and a sufficient time for the driver to perform the steering operation in the direction of decreasing the roll angle before the increasing roll angle becomes excessive can be secured. The occurrence of excessive corner angles on the vehicle body was prevented.
- the control according to the actual lateral acceleration Gy of the final assist force F described in the first embodiment is executed in addition to the variable control of the steering angle ratio n.
- the second embodiment may be configured to execute only variable control of the steering angle ratio n without executing control according to the actual lateral acceleration Gy of the final assist force F.
- the tape described in step 610 is such that the value of the coefficient K t always becomes a fixed value "1" regardless of the value of the actual lateral acceleration Gy in step 610 of FIG. Change the rule.
- the slip ratio of each wheel of the vehicle is used as a control target for bringing the actual lateral acceleration Gy closer to the target lateral acceleration Gyt.
- the wheel cylinder of each wheel Any physical quantity may be used as a control target, as long as it is a physical quantity that changes according to the braking force applied to each wheel, such as the brake fluid pressure.
- the value of the coefficient K t calculated in step 610 of FIG. 6 and the value of the steering angle ratio n calculated in step 1 140 of FIG. Although it has been changed according to the absolute value of the actual lateral acceleration Gy as the roll angle development tendency index value, the roll angle ⁇ ro l 1 generated on the vehicle body as the “excess roll angle generation tendency index value”
- the value of the coefficient K t and the value of the steering angle ratio n may be changed according to the absolute value.
- the CPU 61 Describing a specific process in this case, the CPU 61 repeatedly executes the routine for calculating the roll angle ro ro ll shown in FIG. 15 every predetermined time. Therefore, at the predetermined timing, the CPU 61 starts processing from step 1 500.
- Step 1 Go to Step 1 05 and go to Step 1 for each height of the wheel section Hfr, Hrl, obtained by the height sensor 5 6 ⁇ , 5 6 fr, 5 6 rl and 5 6 rr, and Step 1
- the vehicle height difference ⁇ 5 between the left side of the vehicle and the right side of the vehicle is calculated based on the equation described in 5 0 5.
- the difference in vehicle height ⁇ is an average value of the difference in vehicle height between the left front and the right front of the vehicle and the difference in height between the left rear and the rear right of the vehicle.
- the vehicle height difference ⁇ is a positive value when the vehicle height on the left side of the vehicle body is higher than the vehicle height on the right side of the vehicle body, that is, when the vehicle is turning left, the vehicle height on the left side of the vehicle body is the vehicle body It is set to be a negative value when it is lower than the vehicle height on the right side, that is, when the vehicle is turning to the right.
- step 1150 the CPU 61 proceeds to step 1150 to obtain the values of the vehicle height difference ⁇ calculated in step 1 5 0 5 and the treads of the left and right wheels (eg, left and right rear wheels RL and RR).
- the CPU 61 proceeds to step 1150 to obtain the values of the vehicle height difference ⁇ calculated in step 1 5 0 5 and the treads of the left and right wheels (eg, left and right rear wheels RL and RR).
- the CPU 61 proceeds to step 1150 to obtain the values of the vehicle height difference ⁇ calculated in step 1 5 0 5 and the treads of the left and right wheels (eg, left and right rear wheels RL and RR).
- step 1 5 10 corresponds to the index value acquisition means.
- CPU 6 1 calculates the horizontal axis of the table described in step 6 10 of FIG. 6 at step 1 5 10 of FIG. 15 instead of the absolute value of the actual lateral acceleration Gy.
- the CPU 6 calculates the horizontal axis of the table described in step 1405 in Figure 14 at step 1 5 0 in Figure 15 instead of the absolute value of the actual lateral acceleration Gy.
- the steering angle ratio n is calculated by using the absolute value of the roll angle 0 roll and replacing the threshold Gyth with the threshold 0 rollth corresponding to the same value Gyth.
- the value of the coefficient Kt and the value of the steering angle ratio n are changed in accordance with the absolute value of the roll angle roll roll generated in the vehicle body.
- the value of the coefficient Kt calculated in step 610 of FIG. 6 and the value of the steering angle ratio n calculated in step 1405 of FIG. As the driver's steering 2 1 rotation speed (steering operating speed) absolute It may be configured to change according to the value.
- the steering wheel rotation speed ⁇ s is a time derivative value of steering rotation speed ⁇ 's calculated by the equation)
- the threshold value Gyth is replaced with the threshold value 0'sth corresponding to the same value Gyth, and the coefficient Kt and the steering angle Calculate the ratio n.
- Ssl is the previous value obtained by the steering angle sensor 52 at the time of the previous execution of the routine of FIGS. It is a steering angle
- ⁇ is the above-mentioned predetermined time which is an operation cycle of each routine.
- the excessive roll angle occurrence tendency index value may be the sum of the absolute value of the actual lateral acceleration Gy, the absolute value of the roll angle 0 roll, and the absolute value of the steering rotation speed. It may be the sum of values (weighted values) obtained by multiplying each value by a predetermined coefficient.
- the absolute values ones having a value exceeding the corresponding threshold (if there are a plurality of values exceeding the corresponding threshold, among the respective absolute values, The one with the largest degree of deviation from the corresponding threshold value above may be adopted as the “over roll angle tendency index value”.
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- Regulating Braking Force (AREA)
Abstract
Description
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Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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EP03766641A EP1553007A1 (en) | 2002-08-02 | 2003-07-28 | Steering device of vehicle |
US10/522,787 US20050256620A1 (en) | 2002-08-02 | 2003-07-28 | Steering device of vehicle |
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JP2002225676A JP2004066873A (ja) | 2002-08-02 | 2002-08-02 | 車両の操舵装置 |
JP2002-225676 | 2002-08-02 |
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WO2004012977A1 true WO2004012977A1 (ja) | 2004-02-12 |
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US (1) | US20050256620A1 (ja) |
EP (1) | EP1553007A1 (ja) |
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US7373230B2 (en) * | 2004-06-02 | 2008-05-13 | Toyota Jidosha Kabushiki Kaisha | Steering assist apparatus and method for vehicle |
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US7041029B2 (en) * | 2004-04-23 | 2006-05-09 | Alto U.S. Inc. | Joystick controlled scrubber |
JP4617733B2 (ja) * | 2004-06-17 | 2011-01-26 | 日産自動車株式会社 | 車両用内輪空転防止制御装置 |
JP2006123611A (ja) * | 2004-10-26 | 2006-05-18 | Nissan Motor Co Ltd | 車両用操舵装置 |
JP4747720B2 (ja) * | 2005-08-03 | 2011-08-17 | 日産自動車株式会社 | 車両用操舵装置 |
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Also Published As
Publication number | Publication date |
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JP2004066873A (ja) | 2004-03-04 |
EP1553007A1 (en) | 2005-07-13 |
US20050256620A1 (en) | 2005-11-17 |
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