JP2009220617A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress an incongruity sense of a driver during vehicle turn by a braking/driving force difference between right and left wheels. <P>SOLUTION: An electronic controller 1 has: a braking/driving force calculation means calculating braking/driving force of the wheels generating the braking/driving force difference between the right and left wheels of front wheels W<SB>FR</SB>, W<SB>FL</SB>and rear wheels W<SB>RR</SB>, W<SB>RL</SB>generating desired vehicle yaw gain; and a braking/driving force control means controlling braking/driving force generation devices (in-wheel motors 40<SB>FL</SB>, 40<SB>FR</SB>, 40<SB>RL</SB>, 40<SB>RR</SB>, a brake actuator 33 or the like) each capable of individually applying the braking/driving force to each wheel such that the wheels have the braking/driving force obtained by the braking/driving force calculation means. The braking/driving force calculation means calculates the braking/driving force of the wheels such that a difference between magnitude of vehicle turn outer direction lateral force applied to the vehicle gravity center according to the braking/driving force difference between the right-and-left wheels in the front wheels W<SB>FR</SB>, W<SB>FL</SB>and magnitude of vehicle turn inner direction lateral force applied to the vehicle gravity center according to the braking/driving force difference between the right-and-left wheels in the rear wheels W<SB>RL</SB>, W<SB>RR</SB>, becomes small. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a steering device capable of turning a vehicle by a difference in braking / driving force generated between left and right wheels.

  Conventionally, a technique is known in which a turning moment is generated in a vehicle by generating a braking / driving force difference between the left front wheel and the right front wheel, and the vehicle is turned by the turning moment. For example, Patent Document 1 below discloses an electric vehicle that changes the torque distribution of the motors on the left and right front wheels based on the steering operation amount (steering force) of the steering wheel, thereby providing the same effect as power steering. A drive system is disclosed. Further, in Patent Document 2 below, when a so-called steer-by-wire type steering device breaks down, a torque difference corresponding to the steering operation amount (operation angle) of the steering wheel is generated in the output torque of the motor at the left and right front wheels. A steering control device that secures a steering function in the event of a failure by generating torque steer according to the torque difference is disclosed.

Japanese Patent Laid-Open No. 9-117016 JP 2007-161191 A

  Here, when the vehicle yaw gain in the turning direction according to the steering operation amount of the steering wheel is obtained only by the torque difference between the left and right wheels in the front wheels, as in the above-described conventional technology, the size of the left and right front wheels is determined. The different output torques generate lateral force toward the vehicle turning outside with respect to the center of gravity of the vehicle (hereinafter referred to as “vehicle turning outward lateral force”), so the left and right front wheels are steered. The rise of the lateral acceleration of the vehicle is delayed as compared with the turning of the accompanying vehicle. For this reason, the vehicle causes a planar motion different from that at the time of turning of the vehicle by turning the left and right front wheels, so that the driver feels uncomfortable with the turning operation of the vehicle. In addition, the smaller the time difference between the vehicle yaw rate and the vehicle lateral acceleration rises, the more the vehicle performs a turning motion with a good grip feeling. Therefore, this conventional technique also gives the driver a sense of incongruity from this viewpoint.

  Accordingly, the present invention has an object to provide a steering device that improves the disadvantages of the conventional example and can suppress a driver's uncomfortable feeling when the vehicle is turned by a difference in braking / driving force between left and right wheels. And

  In order to achieve the above object, according to the first aspect of the present invention, a braking / driving operation for calculating a braking / driving force of a wheel that generates a braking / driving force difference between the left and right wheels of the front wheel and the rear wheel that achieves a desired vehicle yaw gain is achieved. Braking / driving force control for controlling the force calculating means and the braking / driving force generating device capable of individually applying braking / driving force to each wheel so that the wheel becomes the braking / driving force obtained by the braking / driving force calculating means Means. The braking / driving force calculating means is provided with the magnitude of the lateral force in the vehicle turning outward direction acting on the center of gravity of the vehicle and the difference in braking / driving force between the left and right wheels on the rear wheel. The braking / driving force of the wheel is calculated so that the difference from the lateral force in the vehicle turning inward direction acting on the center of gravity of the vehicle becomes small.

  Since the steering device according to the first aspect generates a braking / driving force difference capable of obtaining a desired vehicle yaw gain between the left and right wheels of the front wheel and the rear wheel, the steered wheel is steered to the target turning angle. Even if the operation becomes impossible, the turning moment associated with the vehicle yaw gain can be applied to the vehicle, and the vehicle can be turned according to the steering operation amount of the steering wheel of the driver. At that time, the left and right wheels of the front wheel and the rear wheel have a braking / driving force difference that reduces the difference between the lateral force in the vehicle turning outward direction and the lateral force in the vehicle turning direction. It is possible to suppress the generation of the vehicle lateral force accompanying the application of the force difference, and the vehicle performs the vehicle turning operation in which the driver feels uncomfortable.

  The braking / driving force calculating means, when the vehicle yaw gain accompanying turning of the steered wheels is insufficient with respect to the vehicle yaw gain corresponding to the steering operation amount of the steering wheel, as in the invention described in claim 2, The vehicle yaw gain is set as a desired vehicle yaw gain. As a result, the steering device can achieve the target vehicle with the vehicle yaw gain due to the turning of the steered wheels and the insufficient vehicle yaw gain due to the difference in braking / driving force between the left and right wheels of the front and rear wheels, without causing the driver to feel uncomfortable. A yaw gain (a vehicle yaw gain corresponding to the steering operation amount of the steering wheel) can be obtained.

  Further, the braking / driving force calculating means may be configured to set a vehicle yaw gain according to the steering operation amount of the steering wheel as a desired vehicle yaw gain, as in the third aspect of the invention. As a result, this steering device obtains a target vehicle yaw gain (vehicle yaw gain corresponding to the steering operation amount of the steering wheel) by the braking / driving force difference between the left and right wheels of the front wheels and the rear wheels without giving the driver a sense of incongruity. be able to.

  Further, the braking / driving force calculating means includes a vehicle turning outward lateral force acting on the center of gravity of the vehicle in accordance with a braking / driving force difference between the left and right wheels at the front wheel and a distance between the left and right wheels at the rear wheel. It may be configured to calculate the braking / driving force of the wheel such that the lateral force in the vehicle turning inward direction acting on the center of gravity of the vehicle cancels with the braking / driving force difference. As a result, the generation of the vehicle lateral force accompanying the application of the braking / driving force difference can be eliminated, so that the driver does not feel more uncomfortable.

  Here, the braking / driving force calculating means is configured to obtain the driving force as the braking / driving force of the turning outer wheel and to obtain the braking force as the braking / driving force of the turning inner wheel, as in the invention of claim 5. .

  The steering device according to the present invention provides an appropriate braking / driving force difference between the left and right wheels of the front wheel and the rear wheel even when the steered wheel cannot be steered to the target turning angle. The turning moment accompanying the target vehicle yaw gain equivalent to when the steered wheels are steered to the target turning angle can be applied to the vehicle. Therefore, this steering device can cause the vehicle to perform a vehicle turning operation in accordance with the steering operation amount of the steering wheel of the driver, regardless of whether or not the steering operation of the steered wheels to the target turning angle is impossible. it can. Furthermore, this steering device has a braking / driving force difference that reduces or cancels the difference between the lateral force in the vehicle turning outward direction and the lateral force in the vehicle turning direction on the left and right wheels of the front and rear wheels. Therefore, it is possible to suppress or eliminate the generation of the vehicle lateral force accompanying the application of the braking / driving force difference, and it is possible to cause the vehicle to perform a vehicle turning operation with a sense of incongruity for the driver.

  Embodiments of a steering apparatus according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments.

[Example 1]
A first embodiment of a steering apparatus according to the present invention will be described with reference to FIGS.

  Initially, the main structure of the steering apparatus of the present Example 1 is demonstrated based on FIG.

  The steering device according to the first embodiment obtains a target turning angle of a steered wheel based on a steering operation amount of a steering wheel by a driver, and steers the steered wheel to the target turning angle. Here, it is a so-called steer-by-wire steering device in which there is no mechanical connection between the steering wheel and the left and right steered wheels of the vehicle, and the steered angle of the steered wheels is controlled by an electronic control unit (ECU). The thing is illustrated. In addition, the target turning angle shown here is an angle with a starting point when the turning angle is not given to the steered wheels (that is, when the vehicle is in a straight traveling state).

As shown in FIG. 1, this steer-by-wire steering device includes an electronic control device 1 that performs calculation processing of a target turning angle and steering operation control of the steered wheels (front wheels) W _FL and W _FR , and a driver steers. Steering wheel 11 as a rotational operation member used at the time of operation, a steering shaft 12 as a rotation shaft connected to the steering wheel 11, and a turning force for each of the steered wheels W _FL and W _FR so as to have a target turning angle. Wheel turning angle applying means 20 for adding

  First, the electronic control unit 1 includes a CPU (Central Processing Unit) (not shown), a ROM (Read Only Memory) that stores a predetermined steering control program in advance, and a RAM (Random) that temporarily stores the calculation result of the CPU. (Access Memory) and a backup RAM for storing information prepared in advance. The electronic control device 1 is provided with various means for performing calculations and settings necessary for executing steering control.

As the means, target turning angle setting means that obtains and sets the target turning angle of the steered wheels W _FL and W _FR based on the steering operation amount of the steering wheel 11, and the vehicle so that the target turning angle is obtained. There is wheel steering control means for driving the wheel turning angle applying means 20 to steer the respective steered wheels W _FL and W _FR .

  The target turning angle setting means and the wheel turning control means are set or controlled by a well-known method in each technical field. Further, the steering operation amount of the steering wheel 11 is detected from the steering operation amount detection means 13 shown in FIG. The steering operation amount may be a steering angle of the steering wheel 11 by the driver, a steering force applied to the steering wheel 11 by the driver, or the like.

The electronic control device 1 exemplified here includes a braking / driving force control means capable of individually controlling braking / driving forces for all the wheels W _FL , W _FR , W _RL , W _RR , A braking / driving force calculating means for calculating each braking / driving force is also provided.

  Next, the wheel turning angle providing means 20 will be described.

For example, as the wheel turning angle imparting means 20 of the first embodiment, the electric motor 21 is driven based on the command value of the target turning angle from the wheel turning control means of the electronic control device 1, and left and right are driven by the driving force. The tie rods TL and TR are moved in the left-right direction of the vehicle to turn the steered wheels W _FL and W _FR . That, in this wheel turning angle imparting means 20, the electric motor 21 is used as a steering force generating means for generating a steering force with respect to the steered wheels W _FL, W _FR respective. For example, although not shown, the electric motor 21 of the first embodiment includes a tubular rotor, a stator or the like covered on the outer peripheral side of the rotor, and a shaft connected to the tie rods TL and TR inside the rotor. It is inserted.

Here, the wheel turning angle imparting means 20 of the first embodiment is provided with a turning force transmission mechanism 22 that transmits the turning force of the electric motor 21 to the tie rods TL and TR. As this turning force transmission mechanism 22, for example, a spiral ball screw formed on the inner peripheral surface of the rotor of the electric motor 21 or a screw screw nut attached to the rotor, or an outer peripheral surface of the shaft, not shown. And a ball screw mechanism composed of a plurality of balls disposed between the ball screw nut and the ball screw portion. In this type of steering force transmission mechanism 22, the ball screw nut rotates in the circumferential direction as the electric motor 21 is driven (that is, rotation of the rotor), and the shaft is moved to the left or right of the vehicle according to the rotation direction. Thus, the steered wheels W _FL and W _FR are steered through the tie rods TL and TR connected to both ends of the shaft.

Further, the wheel turning angle imparting means 20 is provided with a turning angle sensor 23 for detecting the turning angles of the steered wheels W _FL and W _FR . For example, as the turning angle sensor 23, a sensor which is disposed in the vicinity of the outer peripheral surface of the shaft or the tie rods TL, TR and detects the rotational angle of the shaft or the movement amount in the axial direction (the left-right direction of the vehicle) is used. . In the case of this type of turning angle sensor 23, the wheel turning control means determines that the actual turning angle (hereinafter referred to as “actual turning angle”) is the target turning based on the detected rotation angle or movement amount. It can be determined whether or not it is a corner.

By the way, in the steering apparatus of the first embodiment, since there is no mechanical connection between the steering wheel 11 and the steered wheels W _FL and W _FR , the wheel steered angle giving means 20 operates well due to deterioration over time. If it disappears, the actual turning angles of the steered wheels W _FL and W _FR may be smaller than the target turning angle. In other words, the steering operation amount detection means 13 appropriately detects the steering operation amount of the driver's steering wheel 11, and the wheel steering control means of the electronic control device 1 makes the target turning angle based on the steering operation amount. Even if the wheel turning angle imparting means 20 is driven and controlled, when the wheel turning angle imparting means 20 cannot maintain the initial performance and cannot operate properly, the wheel turning angle imparting means 20 causes the steered wheels W to be turned. _FL, there is a possibility that it becomes impossible to steer the W _FR to the target turning angle. Therefore, at that time, the vehicle cannot perform the vehicle turning operation according to the driver's steering operation (the amount of steering operation of the driver's steering wheel 11).

Therefore, the steering apparatus of the first embodiment, the steered wheels W _FL, even turning operation to the target turning angle of the W _FR has become impossible, the target steering the steered wheels W _FL, W _FR A vehicle turning operation equivalent to that when turning to a corner can be realized.

Here, in order to cause the vehicle to perform the vehicle turning operation according to the driver's steering operation even if the wheel turning angle giving means 20 is not in good condition, the turning wheels W _FL and W _FR are turned to the target turning angle. A turning moment may be applied to the vehicle with a vehicle yaw gain equivalent to the time (hereinafter referred to as “target vehicle yaw gain”). That is, when the steered wheels W _FL and upset wheel turning angle imparting means _20, W _FR can not be steered to the target steering angle, the vehicle due to the turning to the actual turning angle of the steered wheels W _FL, W _FR Yogein (Hereinafter referred to as “steering vehicle yaw gain”) is smaller than the target vehicle yaw gain, so that a turning moment associated with the insufficient vehicle yaw gain (= target vehicle yaw gain−steering vehicle yaw gain) is generated in the vehicle. It is sufficient that the vehicle yaw gain corresponding to the shortage is set as a desired vehicle yaw gain, so that the vehicle turning operation equivalent to that when the steered wheels W _FL and W _FR are steered to the target turning angle can be realized.

In the first embodiment, by generating the braking / driving force differences ΔFf, ΔFr between the left and right wheels of the front wheels W _FL , W _FR and the rear wheels W _RL , W _RR , this corresponds to the insufficient vehicle yaw gain. Compensate for the turning moment.

Here, the braking and driving force difference ΔFf front wheels _{W FL, W FR} is left and right front wheels _W FL, _{respectively,} is generated by each applying different longitudinal force on the _{W FR.} Further, the rear wheels _{W RL,} longitudinal force difference ΔFr of _{W RR} are respective right and left rear wheels _{W RL,} it is generated by adding each different longitudinal force on the _{W RR.} Here, as the braking / driving force, a driving force is applied to each of the front and rear turning outer wheels, and a braking force is applied to each of the front and rear turning inner wheels. Here, the driving force difference ΔFf is generated by setting the driving force of the outer turning wheel and the braking force of the inner turning wheel at the front wheels W _FL and W _FR to the same magnitude. On the other hand, similarly for the rear wheels W _RL and W _RR , the driving force difference ΔFr is generated by setting the driving force of the outer turning wheel and the braking force of the inner turning wheel to the same magnitude. That is, the same braking / driving force Ff in the opposite direction is applied to the left and right front wheels W _FL and W _FR , and the same braking / driving force in the opposite direction to the left and right rear wheels W _RL and W _RR. Apply force Fr.

The reason why the braking / driving force differences ΔFf and ΔFr are respectively provided between the left and right wheels of the front wheels W _FL and W _FR and the rear wheels W _RL and W _RR is that the front wheels W _FL and W _FR or the rear wheels W _RL and W _RR This is because when a braking / driving force difference is applied to only one of the wheels, a lateral force on the vehicle is applied to the vehicle by the braking / driving forces of the left and right wheels to create the braking / driving force difference. _{If the} braking / driving force differences ΔFf and ΔFr are generated at the same time in _FL and W _FR and the rear wheels W _RL and W _RR , the lateral force acting on the entire vehicle due to the lateral force acting in the opposite direction of the vehicle This is because the directional force (hereinafter referred to as “vehicle lateral force”) can be reduced.

For example, as shown in FIG. 2, the left side longitudinal force to the front wheels _{W FL} (braking force) longitudinal force to the right front wheel _{W FR} with added Ff (driving force) Ff added, the front wheels _{W FL, W FR} only the braking-driving It is assumed that a turning moment corresponding to the deficient vehicle yaw gain is generated by adding the force difference ΔFf. In this case, a lateral force in the vehicle turning outward direction (a lateral force directed toward the outside of the vehicle turning) Fs _out acts on the vehicle center of gravity Cg, so that the same inconvenience as described above occurs. That is, when that caused the turning moment corresponding to the shortage of vehicles Yogein only longitudinal force difference ΔFf front wheels W _FL, W _FR is possible to steer the front wheels W _FL, a W _FR to the target turning angle As a result, the rise of the lateral acceleration of the vehicle is delayed as compared with the normal vehicle turning in which the target vehicle yaw gain is obtained. In this case, the vehicle causes a planar motion different from that during normal vehicle turning, so that the driver feels uncomfortable with the behavior.

Here, a line L1 connecting the center line Lc in the vehicle longitudinal direction and the center of the front wheel on the outside of the turn to which the vehicle center of gravity Cg and the braking / driving force (driving force) Ff are applied (in the illustration of FIG. 2, the right front wheel _WFR ) is formed. the angle "θfd", formed by the line L2 connecting the center of the center line Lc and the vehicle center of gravity Cg and the braking and driving force front turning inner adding (braking force) Ff (in the illustration of Figure 2, the left front wheel W _FL) The angle is “θfb”. In this case, the component force along the line L1 of the braking / driving force (driving force) Ff is “Ff * cos θfd”, and the component force along the line L2 of the braking / driving force (braking force) Ff is “Ff * cos θfb”. Become. The respective component forces Ff * cos θfd and Ff * cos θfb act on the vehicle center of gravity Cg, and the resultant force “Ff * cos θfd * sin θfd + Ff * cos θfb * sin θfb” acts as a vehicle turning outward lateral force Fs _out . That is, the vehicle turning outward lateral force Fs _out can be expressed by the following Equation 1.

Further, on the contrary, for example, as shown in FIG. 3, the longitudinal force on the left rear wheel W _RL (braking force) longitudinal force on the right rear wheel W _RR with added Fr (driving force) Fr and the mixture was It is assumed that a turning moment corresponding to a deficient vehicle yaw gain is generated by attaching a braking / driving force difference ΔFr only to the wheels W _RL and W _RR . In this case, each braking / driving force Fr generates a lateral force (hereinafter referred to as “vehicle turning inward lateral force”) Fs _in with respect to the vehicle center of gravity Cg. The vehicle performs a planar motion that makes the driver feel uncomfortable due to a vehicle lateral acceleration different from that during normal vehicle turning.

Here, a line L3 connecting the center line Lc in the longitudinal direction of the vehicle and the center of the rear outer wheel (right rear wheel _{WRR in} the illustration of FIG. 3) to which the vehicle center of gravity Cg and braking / driving force (driving force) Fr are applied. connecting the centers of the "θrd" rear wheel inner adding the center line Lc and the vehicle center of gravity Cg and the longitudinal force (braking force) Fr (in the illustration of Figure 3 and the left rear wheel W _RL) the angle between The angle formed by the line L4 is defined as “θrb”. In this case, the component force along the line L3 of the braking / driving force (driving force) Fr is “Fr * cos θrd”, and the component force along the line L4 of the braking / driving force (braking force) Fr is “Fr * cos θrb”. Become. Each of the component forces Fr * cos θrd and Fr * cos θrb acts on the vehicle center of gravity Cg, and the resultant force “Fr * cos θrd * sin θrd + Fr * cos θrb * sin θrb” acts as a lateral force Fs _{in in the} vehicle turning direction. That is, the vehicle turning inward lateral force Fs _in can be expressed by the following Equation 2.

Thus, the front wheels _{W FL,} longitudinal force difference ΔFf in _{W FR} is exercising vehicle turning outward lateral force _{Fs out} the vehicle, the rear wheels _{W RL,} the longitudinal force difference in _{W RR} .DELTA.fr the vehicle turning outwardly lateral force A vehicle turning inward lateral force Fs _in opposite to Fs _{out is applied} to the vehicle. Then, the size of the vehicle turning outward lateral force _{Fs out} of size and vehicle turning in a direction lateral force _{Fs in} is, each of the wheels _{W FL, W FR, W RL} , braking and driving force of the _{W RR} Ff, the size of Fr Changes in size depending on the size. This because, in the present embodiment 1, its respective longitudinal force difference DerutaFf, while generating a .DELTA.fr, further difference of the vehicle turning outward lateral force Fs size and vehicle turning in a direction lateral force Fs _in the size of the _out The braking / driving forces Ff and Fr for reducing the vehicle _speed are added to the wheels W _FL , W _FR , W _RL and W _RR , thereby reducing the lateral force of the vehicle and suppressing the driver's uncomfortable feeling. Therefore, the braking / driving force calculating means of the electronic control unit 1 according to the first embodiment is configured to be able to obtain the braking / driving forces Ff, Fr of such wheels W _FL , W _FR , W _RL , W _RR. To do.

The braking / driving force Ff, Fr of each of the wheels W _FL , W _FR , W _RL , W _RR is most preferably the same as the vehicle turning inward lateral force Fs _out and the vehicle turning inward lateral force Fs _in. In addition, these cancel each other and the lateral force of the vehicle becomes “0”. Therefore, the braking / driving force calculating means exemplified here is the braking / driving of the wheels W _FL , W _FR , W _RL , W _RR where the vehicle lateral force becomes “0” (that is, the following expression 3 is satisfied). The forces Ff and Fr are calculated.

The braking / driving force calculation means calculates the braking / driving force Fr of the rear wheels W _RL and W _RR using the following equation 4 obtained by expanding the equation 3 by substituting the equations 1 and 2. That is, the braking / driving force Fr of the rear wheels W _RL and W _RR obtained by the equation 4 is used to cancel the vehicle turning outward lateral force Fs _out generated with the braking / driving force difference ΔFf between the front wheels W _FL and W _FR . This is a force that creates a braking / driving force difference ΔFr that generates a lateral force Fsin _{in the} vehicle turning inward direction.

The braking / driving forces Fr of the rear wheels W _RL and W _RR can be derived if the respective angles θfd, θfb, θrd, and θrb and the braking / driving forces Ff of the front wheels W _FL and W _FR become clear.

As the respective angles θfd, θfb, θrd, and θrb, fixed values unique to the vehicle that are known in advance when the vehicle center of gravity Cg is unchanged may be used. However, the position of the center of gravity Cg of the vehicle changes depending on the occupant and the load amount, and also changes depending on the turning posture. For this reason, it is desirable that the electronic control device 1 be provided with vehicle state calculation means for obtaining the angles θfd, θfb, θrd, and θrb corresponding to the position of the changing vehicle center of gravity Cg. Here, the position of the center of gravity Cg of the vehicle can be estimated using the wheel base and tread of the vehicle, the loads of the wheels W _FL , W _FR , W _RL , W _RR , and the like. Therefore, for example, a load meter or a load sensor (not shown) is provided on each of the wheels W _FL , W _FR , W _RL , W _RR so that the vehicle state calculation means estimates the position of the vehicle center of gravity Cg.

On the other hand, the braking / driving force Ff of the front wheels W _FL and W _FR is obtained by being defined as the following Expression 5. “Θs” in Equation 5 is a turning angle of the steered wheels W _FL and W _FR necessary for obtaining a deficient vehicle yaw gain, and is obtained by subtracting the actual turning angle from the target turning angle. It is a value that can be obtained. “Gf” is a difference in braking / driving force between the front wheels W _FL and W _FR per turning angle that causes the vehicle to generate a turning moment equivalent to that when the steered wheels W _FL and W _FR are turned once. This is set in advance through experiments and simulations. In the first embodiment, the same driving force and braking force are applied to the turning outer wheels and turning inner wheels of the front wheels W _FL and W _FR , so that “Gf / 2” rotates the steered wheels W _FL and W _FR once. It can be said that this is the braking / driving force Ff of the front wheels W _FL and W _FR per steering angle that causes the vehicle to generate a turning moment equivalent to that when the vehicle is steered.

Here, the braking / driving force generating device that is controlled by the braking / driving force control means of the electronic control unit 1 and applies the braking / driving force to the wheels W _FL , W _FR , W _RL , W _RR individually will be described. . Here, for each wheel W _FL , W _FR , W _RL , W _RR , a braking force generator that can individually apply a braking force to each wheel W _FL , W _FR , W _RL , W _RR , and each wheel W _FL , W _FR , W _RL , W _RR The braking / driving force generating device will be described separately for the driving force generating device capable of individually applying the driving force.

  First, the braking force generator will be described.

For example, here, as shown in FIG. 1, the braking means 31 _FL , 31 _FR , 31 _RL , 31 _RR for each wheel W _FL , W _FR , W _RL , W _{RR, and} each of these braking means 31 _FL , 31 _FR , 31 _RL , 31 _RR hydraulic pipes 32 _FL , 32 _FR , 32 _RL , 32 _RR for supplying brake hydraulic pressure, and brakes of these hydraulic pipes 32 _FL , 32 _FR , 32 _RL , 32 _RR A hydraulic braking force generator having at least hydraulic pressure adjusting means (hereinafter referred to as “brake actuator”) 33 for individually adjusting hydraulic pressure will be described.

The braking means 31 _FL , 31 _FR , 31 _RL , 31 _RR are a disc rotor for each wheel W _FL , W _FR , W _RL , W _RR , and mechanical control by pressing these disc rotors respectively. A brake pad for generating power and a caliper provided with a piston, and the piston is operated by the brake hydraulic pressure supplied from the respective hydraulic pipes 32 _FL , 32 _FR , 32 _RL , 32 _RR. Thus, a braking force corresponding to the magnitude of the brake fluid pressure is generated.

  The braking force generator also includes a brake pedal 34 that is operated when the driver generates a braking force, and a brake master cylinder 35 that is driven in response to a depression operation of the brake pedal 34 by the driver. Has been deployed. Further, although not shown, this braking force generator is also provided with a booster for increasing the pressure generated by depressing the brake pedal 34 and inputting it to the brake master cylinder 35.

The braking / driving force control means drives and controls the brake actuator 33. As a result, only the braking force (braking torque) corresponding to the amount of brake operation by the driver can be applied to the wheels W _FL , W _FR , W _RL , W _RR , or the brakes whose pressure has been increased or decreased. A braking force (braking torque) by hydraulic pressure can also be applied.

  Next, the driving force generator will be described.

For example, here, as shown in FIG. 1, in-wheel motors 40 _FL , 40 _FR , 40 _RL , 40 _RR provided for the respective wheels W _FL , W _FR , W _RL , W _RR are prepared as driving force generators. ing. Each of the in-wheel motors 40 _FL , 40 _FR , 40 _RL , 40 _RR operates as a driving force generator when driven by the braking / driving force control means.

On the other hand, these in-wheel motors 40 _FL , 40 _FR , 40 _RL , 40 _RR are regeneratively driven by the braking / driving force control means with respect to the wheels W _FL , W _FR , W _RL , W _RR . Generate braking force. Therefore, each of these in-wheel motors 40 _FL , 40 _FR , 40 _RL , 40 _RR can be operated as a braking force generator. The braking / driving forces (braking forces) Ff, Fr of the turning inner wheel in the first embodiment are the in-wheel motors 40 _FL , 40 _FR , 40 _RL , operated only as a braking force generator by hydraulic pressure or as a braking force generator. It may be generated only by 40 _{RR, or} may be generated by using a braking force generating device by the hydraulic pressure and in-wheel motors 40 _FL , 40 _FR , 40 _RL , 40 _RR operated as a braking force generating device. .

  Hereinafter, the operation of the steering apparatus according to the first embodiment will be described with reference to the flowchart of FIG.

First, various detection values are input to the electronic control unit 1 (step ST5). The detected value input here is information necessary for turning at least the steered wheels W _FL and W _FR , and is the steering operation amount of the steering wheel 11 detected from the steering operation amount detection means 13.

  The target turning angle setting means of the electronic control device 1 calculates the target turning angle based on the steering operation amount of the steering wheel 11 (step ST10).

For example, here, the target turning angle corresponding to the steering operation amount is read from the target turning angle map data (not shown). The target turning angle map data is obtained by setting a correspondence relationship between the steering operation amount and the target turning angle by conducting experiments and simulations in advance. The correspondence relationship is, for example, a comparison with a conventional steering device (where the steering wheel 11 and the steered wheels W _FL , W _FR are mechanically connected) while suppressing a sudden change in the behavior of the vehicle. There is a possibility that the driver does not feel uncomfortable.

  Subsequently, the steering device state determining means of the electronic control device 1 determines whether the operating state of the steering device is normal or abnormal (step ST15).

  The determination in step ST15 is performed according to the difference between the actual turning angle detected by the turning angle sensor 23 and the target turning angle obtained in step ST10. In other words, the steering device state determination means has the actual turning angle coincident with the target turning angle or the difference between the actual turning angle and the target turning angle is within a predetermined range (considering design tolerances and play). If it is within a minute range), it is determined that the operating state of the steering device is in a normal state. On the other hand, in this steering device state determination means, if the actual turning angle and the target turning angle do not match or the difference between the actual turning angle and the target turning angle exceeds a predetermined range, It is determined that some abnormality has occurred in the steering device. For this reason, the determination in step ST15 is performed using the determination result of the operating state of the steering device executed before this determination. Therefore, the determination result of the operating state of the steering device that has been executed in advance is stored in, for example, a RAM or the like as history information about the operating state.

Here, in the case where the target turning angle setting means is set including the turning speeds of the steered wheels W _FL and W _FR , until the final target turning angle in step ST10 is reached after the turning is started. You can know the target turning angle that changes every moment. Therefore, in this case, if the steered wheels W _FL and W _FR are being steered, the actual steered angle and the target steered angle at the time of determination in step ST15 are compared, and the current operating state of the steering device is compared. May be judged.

When it is determined in step ST15 that the operating state of the steering device is abnormal, the braking / driving force calculating means of the electronic control device 1 is set so that the wheel turning angle providing means 20 has the target turning angle obtained in step ST10. The actual turning angles of the steered wheels W _FL and W _FR when the drive control is performed are estimated (step ST20).

  In step ST20, estimation is performed based on the relationship between the target turning angle and the actual turning angle in consideration of the current operating state of the steering device. The relationship between the target turning angle and the actual turning angle is the relationship between the target turning angle and the actual turning angle, and the estimated actual turning angle with respect to the target turning angle that reflects the deviation. The information is created, for example, as estimated actual turning angle map data (not shown), and stored in the RAM together with the above-described determination result of the operating state of the steering device. The estimated actual turning angle map data is obtained by inferring estimated actual turning angles with respect to other target turning angles based on the correspondence relationship between one or a plurality of target turning angles and actual turning angles. The electronic control device 1 may be made to learn the correspondence between the steering angle and the estimated actual turning angle.

The braking / driving force calculating means is a target vehicle when the steered wheels W _FL and W _FR are steered to the target steered angle in step ST10 (in other words, according to the steering operation amount of the steering wheel 11). The yaw gain and the steered vehicle yaw gain when the steered wheels W _FL and W _FR are steered to the actual steered angle in step ST20 are calculated, and the difference between them is obtained as a shortage of the vehicle yaw gain (step ST25). ).

  In this step ST25, for example, the vehicle yaw gain corresponding to the target turning angle or the steering operation amount of the steering wheel 11 is read from the vehicle yaw gain map data (not shown), and this is set as the target vehicle yaw gain. The vehicle yaw gain map data is obtained by setting a correspondence relationship between the turning angle or the steering operation amount and the vehicle yaw gain by performing experiments and simulations in advance. As the correspondence relationship, for example, one that suppresses a sudden change in the behavior of the vehicle and does not give the driver an uncomfortable feeling due to comparison with a conventional steering device can be considered. In step ST25, the steered vehicle yaw gain is similarly read from the vehicle yaw gain map data in which the correspondence relationship between the steered angle and the vehicle yaw gain is set.

This braking / driving force calculating means generates braking / driving force differences ΔFf, ΔFr between the left and right wheels of the front wheels W _FL , W _FR and the rear wheels W _RL , W _RR for obtaining the deficient vehicle yaw gain. The braking / driving forces Ff and Fr of the wheels W _FL , W _FR , W _RL and W _RR to be calculated are calculated (step ST30).

In this step ST30, left and right front wheels _W FL, respectively using Equation 5 described _above, the seek longitudinal force Ff of _{W FR,} rear wheels _W RL respective right and left using the above-described Expression _4, control of _{W RR} The driving force Fr is obtained. Here, the turning angle θs obtained by subtracting the actual turning angle in step ST20 from the target turning angle in step ST10 is substituted into Equation 5. In addition, the braking / driving force Ff of the front wheels W _FL and W _FR calculated using Expression 5 is substituted into Expression 4.

Subsequently, the electronic control unit 1 steers the steered wheels W _FL and W _FR by the wheel steer control means, and controls and drives the wheels W _FL , W _FR , W _RL and W _RR by the braking / driving force control means. Force control is executed (step ST35).

In this step ST35, the wheel turning control means drives and controls the wheel turning angle providing means 20 so as to achieve the target turning angle in step ST10, thereby turning the respective steered wheels W _FL and W _FR . Here, since it is determined that the operation state of the steering device is abnormal, the steered wheels W _FL and W _FR steer only to the actual steered angle in step ST20 which is smaller than the target steered angle.

On the other hand, the braking / driving force control means includes the brake actuator 33 and the in-wheel motors 40 _FL , 40 _FR so that the braking / driving forces Ff, Fr obtained in step ST30 are applied to the wheels W _FL , W _FR , W _RL , W _RR. , 40 _RL , 40 _RR are controlled. That is, the braking / driving force control means generates braking / driving force differences ΔFf (= 2Ff) and ΔFr (= 2Fr) between the left and right wheels of the front wheels W _FL and W _FR and the rear wheels W _RL and W _RR , respectively. .

For example, when the left front wheel _WFL and the rear wheel _WRL are turning inner wheels, and the right front wheel _WFR and the rear wheel _WRR are turning outer wheels, the braking / driving force control means can control the right front wheel _WFR and the rear wheels. the in-wheel motor ₄₀ FR, _{40 RR} of W _RR by power running drive, each longitudinal force to the front wheels _{W FR} and the rear wheels _{W RR} of the right (driving force) Ff, added Fr. At this time, if the braking / driving force control means generates braking / driving forces (braking forces) Ff and Fr only by a hydraulic braking force generator, the brake actuator 33 is controlled to control the left front wheel _WFL and the rear wheel. adjust the brake fluid pressure of the W each _RL of the liquid pressure piping ₃₂ FL, _{32 RL,} the longitudinal force on the front wheels _{W FL} and the rear wheels _{W RL} of the left (braking force) Ff, added Fr. Further, when the braking / driving forces (braking forces) Ff and Fr of the left front wheel W _FL and the rear wheel W _RL are applied only by the in-wheel motors 40 _FL and 40 _RL , the braking / driving force control means The in-wheel motors 40 _FL and 40 _RL are regeneratively driven so as to generate braking / driving forces (braking forces) Ff and Fr. Further, the braking / driving force control means uses a braking force generator by hydraulic pressure and the in-wheel motors 40 _FL and 40 _RL in combination to apply braking / driving force (braking force) Ff to the left front wheel W _FL and the rear wheel W _RL. , Fr can be added.

Here, which of the three forms is used to generate the braking / driving force (braking force) Ff, Fr may be determined according to, for example, the remaining charged amount of the battery (not shown). In other words, if the remaining power storage amount of the battery is in a fully charged state or a state close to this, the regenerative drive of the in-wheel motors 40 _FL and 40 _RL may cause the battery to be overcharged, resulting in a decrease in performance. The braking / driving forces (braking forces) Ff and Fr are generated only by the braking force generating device. Further, if the residual accumulation amount of the battery is low, since it is preferable to charge the battery by regenerative drive of the in-wheel motor ₄₀ FL, _{40 RL,} in this case, the regeneration of the in-wheel motor ₄₀ FL, _{40 RL} A braking / driving force (braking force) Ff, Fr is generated only by driving. Further, when the battery can be charged, the hydraulic braking force generator and each of the in-wheel motors 40 _FL and 40 _RL may be used in combination. In this case, the smaller the remaining charged amount of the battery, the in-wheel motor 40 _FL. , 40 _RL may be allocated with a larger allocation ratio.

The control of this step ST35, the vehicle is a steered vehicle Yogein accompanying turning to the actual turning angle of the steered wheels _{W FL, W FR,} the front wheels _{W FL, W FR} and the rear wheels _{W RL,} the _{W RR} respectively The vehicle yaw gain of the shortage accompanying the braking / driving force difference ΔFf, ΔFr between the left and right wheels can be obtained. That is, this vehicle can obtain a target vehicle yaw gain equivalent to that when the steered wheels W _FL and W _FR are steered to the target steered angle. Therefore, even when the vehicle cannot steer the steered wheels W _FL and W _{FR to} the target steered angle, the vehicle steers the steered wheels W _FL and W _FR to the target steered angle. An equivalent vehicle turning operation, in other words, a vehicle turning operation according to the amount of steering operation of the steering wheel 11 by the driver can be performed.

In the first embodiment, the braking / driving force difference ΔFr is generated not only in the front wheels W _FL and W _FR as the steered wheels but also in the rear wheels W _RL and W _RR in order to obtain a deficient vehicle yaw gain. The vehicle turning inward lateral force Fs _out acting on the vehicle center of gravity Cg due to the braking / driving force difference ΔFf between the front wheels W _FL and W _FR is changed to the vehicle turning inward lateral force Fs accompanying the braking / driving force difference ΔFr between the rear wheels W _RL and W _RR. Can be canceled with _in . As a result, it is possible to eliminate the generation of vehicle lateral force due to the difference in braking / driving force between the left and right wheels. Therefore, the vehicle is turned when the normal vehicle turns with the front wheels W _FL and W _FR being steered to the target turning angle. Vehicle lateral acceleration equivalent to That is, in contrast to the conventional case where the braking / driving force difference is given only to the front wheels W _FL and W _FR , this steering device can prevent a delay in the rise of the vehicle lateral acceleration. Therefore, since the vehicle performs the vehicle turning operation with the same plane motion as that during normal vehicle turning, the driver does not feel uncomfortable with the behavior. In addition, the time difference between the vehicle yaw rate and the lateral acceleration of the vehicle can be reduced in the same way as when turning a normal vehicle, so that the vehicle can perform a turning operation with excellent grip and give the driver a sense of incongruity. Absent.

By the way, when it is determined in step ST15 that the operation state of the steering device is normal, the electronic control device 1 causes the wheel steering control means to perform normal steering control according to the target steering angle (step). ST40). That is, in this step ST40, the wheel turning angle applying means 20 is driven and controlled to turn the respective turning wheels W _FL and W _FR so as to be the target turning angle of step ST10. In this case, since the operating state of the steering device is normal, the steered wheels W _FL and W _FR are steered to the target turning angle, and the vehicle can obtain the target vehicle yaw gain only by this turning control. Therefore, the vehicle at this time can perform the vehicle turning operation according to the steering operation amount of the steering wheel 11 of the driver only by the steering control as usual.

As described above, the steering device according to the first embodiment has the front wheels W _FL and W _FR and the rear wheels W _RL even when the steered wheels W _FL and W _FR cannot be steered to the target turning angle. , _{W RR} left and right wheels of each of the above calculation formula of the braking driving force difference based on equation (4,5) ΔFf, by imparting .DELTA.fr, the steered wheels to the target steered angle _{W FL, W FR} is rolling The turning moment accompanying the target vehicle yaw gain equivalent to that when the vehicle is steered can be applied to the vehicle. Therefore, this steering device performs the vehicle turning operation according to the amount of steering operation of the steering wheel 11 by the driver regardless of whether or not the turning operation of the steered wheels W _FL and W _{FR to} the target turning angle is impossible. You can let the vehicle do it. Further, this steering device has the magnitude of the lateral force Fs _out in the vehicle turning outward direction and the magnitude of the lateral force Fs _{in in} the vehicle turning direction on the left and right wheels of the front wheels W _FL and W _FR and the rear wheels W _RL and W _RR . Since the braking / driving force differences ΔFf and ΔFr that reduce the difference are added, it is possible to suppress the generation of vehicle lateral force due to the application of the braking / driving force difference. It can be done against.

Here, in the above-described example, the actual turning angles of the steered wheels W _FL and W _FR are estimated in step ST20, but the wheel turning angle applying means 20 is set so that the actual turning angle becomes the target turning angle. An actual measurement value (detected by the turning angle sensor 23) when driving is controlled may be used.

[Example 2]
Next, a second embodiment of the steering apparatus according to the present invention will be described with reference to FIG.

  The steering apparatus according to the second embodiment is basically configured substantially the same as the first embodiment described above, and will be described as being applied to the same vehicle as illustrated in the first embodiment.

In the first embodiment described above, the steered wheels W _FL without actuation well the wheel turning angle imparting means _20, when it is not possible to steer the W _FR to the target steered angle, the steered wheels W _FL, steering of the W _FR only Then, the deficient vehicle yaw gain is obtained by the braking / driving force differences ΔFf and ΔFr applied to the left and right wheels of the front wheels W _FL and W _FR and the rear wheels W _RL and W _RR .

However, the target vehicle yaw gain according to the steering operation amount of the driver's steering wheel 11 is not necessarily obtained by turning the steered wheels W _FL and W _FR , and the front wheels W _FL and W _FR and the rear wheels W _RL , W braking and driving force difference was attached to the left and right wheels of each of the _{RR ΔFf,} it may be obtained only in ΔFr. Hereinafter, the operation of the steering apparatus in this case will be described with reference to the flowchart of FIG.

  Also in this case, the electronic control unit 1 receives the target turning based on the steering operation amount after various detection values (the steering operation amount of the steering wheel 11) are input (step ST5), as in the first embodiment. The angle θtgt is calculated (step ST10). Then, the steering device state determination means of the electronic control device 1 determines whether the operating state of the steering device is normal or abnormal (step ST15). Here, when it is determined that the operating state is normal, the electronic control unit 1 causes the wheel turning control means to perform normal turning control according to the target turning angle (step ST40).

  On the other hand, when it is determined in step ST15 that the operating state is abnormal, the braking / driving force calculating means of the electronic control unit 1 in the second embodiment uses the target turning angle in step ST10 or the steering operation amount in step ST5. The corresponding target vehicle yaw gain is calculated (step ST26). The target vehicle yaw gain may be obtained in the same manner as in step ST25 of the first embodiment.

This braking / driving force calculating means generates braking / driving force differences ΔFf, ΔFr between the left and right wheels of the front wheels W _FL , W _FR and the rear wheels W _RL , W _RR for obtaining the target vehicle yaw gain. The braking / driving forces Ff and Fr of the wheels W _FL , W _FR , W _RL and W _RR are calculated (step ST31).

In this step ST31, the braking / driving force Ff of the left and right front wheels W _FL , W _FR is obtained using the following formula 6, and the left and right rear wheels W _RL , W are calculated using the same formula 4 as in the first embodiment. The braking / driving force Fr of _RR is obtained. Here, the formula 6 is obtained by replacing the “steering angle θs” in the formula 5 of the first embodiment with the “target turning angle θtgt”, and the target turning angle θtgt of the above-described step ST10 is substituted. Further, the braking / driving force Ff of the front wheels W _FL and W _FR calculated using the equation 6 is substituted into the equation 4.

Note that Equation 6 calculates the braking / driving force Ff of the front wheels W _FL and W _FR using the information of the target turning angle θtgt, but the braking / driving force Ff of the front wheels W _FL and W _FR is Alternatively, the information may be obtained using information on the steering operation amount of the steering wheel 11.

Subsequently, the braking / driving force control means of the electronic control device 1 controls the brake actuator 33 and the in-wheel motors 40 _FL , 40 _FR , 40 _RL , 40 _RR so that the braking / driving forces Ff, Fr obtained in step ST31 are applied. and executes the wheels _{W FL, W FR, W RL} , the longitudinal force control for _{W RR} (step ST36).

As a result, the front wheels _{W FL, W FR} and the rear wheels _{W RL,} is between the left and right wheels of each of the _{W RR,} the steering wheel _{W FL,} the equivalent of the target vehicle Yogein and when _{the W FR} has been steered to the target steering angle A braking / driving force difference ΔFf, ΔFr that can be obtained is generated. Therefore, even when the vehicle cannot steer the steered wheels W _FL and W _{FR to} the target steered angle, the vehicle steers the steered wheels W _FL and W _FR to the target steered angle. An equivalent vehicle turning operation, in other words, a vehicle turning operation according to the amount of steering operation of the steering wheel 11 by the driver can be performed.

In the second embodiment, in order to obtain the target vehicle yaw gain, the braking / driving force difference ΔFr is generated not only in the front wheels W _FL and W _FR as the steered wheels but also in the rear wheels W _RL and W _RR , The vehicle turning inward lateral force Fs _out acting on the vehicle center of gravity Cg due to the braking / driving force difference ΔFf between W _FL and W _FR is the vehicle turning inward lateral force Fs _in associated with the braking / driving force difference ΔFr between the rear wheels W _RL and W _RR. Can be countered. As a result, it is possible to eliminate the occurrence of vehicle lateral force due to the difference in braking / driving force between the left and right wheels. Therefore, as in the first embodiment, the vehicle _rotates the front wheels W _FL and W _FR to the target turning angle. A vehicle lateral acceleration equivalent to that during turning of the steered normal vehicle occurs. That is, also in the steering device of the second embodiment, it is possible to prevent a delay in the rise of the vehicle lateral acceleration as compared with the conventional case where the braking / driving force difference is given only to the front wheels W _FL and W _FR . Therefore, since the vehicle performs the vehicle turning operation with the same plane motion as that during normal vehicle turning, the driver does not feel uncomfortable with the behavior. In addition, the time difference between the vehicle yaw rate and the lateral acceleration of the vehicle can be reduced in the same way as when turning a normal vehicle, so that the vehicle can perform a turning operation with excellent grip and give the driver a sense of incongruity. Absent.

As described above, the steering device of the second embodiment has the front wheels W _FL and W _FR and the rear wheels W _RL even when the steered wheels W _FL and W _FR cannot be steered to the target turning angle. , _{W RR} left and right wheels of each of the above calculation formula of the braking driving force difference based on equation (5,6) ΔFf, by imparting .DELTA.fr, the steered wheels to the target steered angle _{W FL, W FR} is rolling The turning moment accompanying the target vehicle yaw gain equivalent to that when the vehicle is steered can be applied to the vehicle. Therefore, this steering device performs the vehicle turning operation according to the amount of steering operation of the steering wheel 11 by the driver regardless of whether or not the turning operation of the steered wheels W _FL and W _{FR to} the target turning angle is impossible. You can let the vehicle do it. Further, this steering device has the magnitude of the lateral force Fs _out in the vehicle turning outward direction and the magnitude of the lateral force Fs _{in in} the vehicle turning direction on the left and right wheels of the front wheels W _FL and W _FR and the rear wheels W _RL and W _RR . Since the braking / driving force differences ΔFf and ΔFr that reduce the difference are added, it is possible to suppress the generation of vehicle lateral force due to the application of the braking / driving force difference. It can be done against.

By the way, in the vehicles of the first and second embodiments described above, the steered wheels W _FL and W _FR can be steered to the target steered angle according to the control command of the wheel steer control unit of the electronic control device 1. Therefore, when a useless yaw moment that disturbs the behavior works, the yaw moment in the opposite direction to that yaw moment is applied by turning the steered wheels W _FL and W _FR to stabilize the behavior. Control (so-called vehicle stability control or the like) can be realized.

However, if the wheel turning angle imparting means 20 does not operate well when performing such vehicle behavior stabilization control, the turning angles of the steered wheels W _FL and W _FR are insufficient, and the behavior of the vehicle is stabilized. There is a risk that it will not be possible. For this reason, in order to eliminate such inconvenience, the present invention described in each of the first and second embodiments may be used at the time of executing the vehicle behavior stabilization control, whereby the target turning of the steered wheels W _FL and W _FR is performed. Even if the turning operation to the corner becomes impossible, the behavior of the vehicle can be stabilized.

Further, in each of the embodiments 1 and 2 described above illustrate the wheels _{W FL, W FR, W RL} , W RR respectively provided in-wheel motor _{40 FL, 40 FR, 40 RL} , 40 RR as a driving force generating device However, the driving force generator is not necessarily limited to such a mode. For example, in the case of a four-wheel drive vehicle based on a so-called FR (front engine / rear drive) vehicle or MR (midship engine / rear drive) vehicle, the in-wheel motor 40 _FL provided on the front wheels W _FL and W _{FR respectively.} , 40 _FR and a prime mover such as an internal combustion engine that transmits the driving force to the rear wheels W _RL , W _RR become a driving force generator. In this case, braking / driving force is generated for the front wheels W _FL and W _{FR in the same} manner as in the first and second embodiments. On the other hand, for the rear wheels W _RL and W _RR , the differential device to which the output torque of the prime mover is transmitted may be controlled, and the distribution of the driving force of the left and right wheels may be adjusted according to the braking / driving force difference ΔFr. Furthermore, in the case of a four-wheel drive vehicle based on a so-called FF (front engine / front drive) vehicle, a motor that transmits driving force to the front wheels W _FL and W _FR and a rear wheel W _RL and W _RR are provided respectively. The in-wheel motors 40 _RL and 40 _RR are driving force generators. In this case as well, for the front wheels W _FL and W _FR , the distribution of the driving force of the left and right wheels is controlled by controlling the differential device to which the output torque of the prime mover is transmitted based on the same idea as in the case of an FR vehicle or the like. Adjustment is made according to the driving force difference ΔFf, and the braking / driving force is generated for the rear wheels W _RL and W _{RR in the same} manner as in the first and second embodiments.

  As described above, the steering device according to the present invention is useful for a technique for turning a vehicle by applying a braking / driving force difference between left and right wheels, and suitable for a technique for suppressing a driver's uncomfortable feeling at that time. ing.

It is a figure shown about the structure of the steering device which concerns on this invention. It is a figure explaining the vehicle turning outward lateral force accompanying the braking / driving force difference of a front wheel. It is a figure explaining the vehicle turning inward lateral force accompanying the braking / driving force difference of a rear wheel. 3 is a flowchart for explaining the operation of the steering device according to the first embodiment. 6 is a flowchart for explaining the operation of the steering apparatus according to the second embodiment.

Explanation of symbols

1 Electronic control unit (ECU)
DESCRIPTION OF SYMBOLS 11 Steering wheel 12 Steering shaft 13 Steering operation amount detection means 20 Wheel turning angle provision means 21 Electric motor 22 Steering force transmission mechanism 23 Steering angle sensor 31 _FL , 31 _FR , 31 _RL , 31 _RR braking means 32 _FL , 32 _FR , 32 _RL , 32 _RR hydraulic piping 33 Brake actuator 40 _FL , 40 _FR , 40 _RL , 40 _RR in-wheel motor W _FL , W _FR , W _RL , W _RR wheel

Claims (5)

Braking / driving force calculating means for calculating the braking / driving force of the wheels for generating a braking / driving force difference between the left and right wheels of the front wheel and the rear wheel at which a desired vehicle yaw gain is obtained;
Braking / driving force control means for controlling the braking / driving force generating device capable of individually applying braking / driving force to each wheel so that the wheels have the braking / driving force obtained by the braking / driving force calculating means;
With
The braking / driving force calculating means includes a magnitude of the lateral force in the vehicle turning outward direction acting on the center of gravity of the vehicle and a difference in braking / driving force between the left and right wheels in the rear wheel. A steering apparatus configured to calculate a braking / driving force of a wheel such that a difference from a lateral force in a vehicle turning inward direction acting on a vehicle center of gravity becomes small.   The braking / driving force calculation means sets the deficient vehicle yaw gain as the desired vehicle yaw gain when the vehicle yaw gain associated with the turning of the steered wheels is insufficient with respect to the vehicle yaw gain corresponding to the steering operation amount of the steering wheel. The steering apparatus according to claim 1, wherein the steering apparatus is configured so as to cause   2. The steering apparatus according to claim 1, wherein the braking / driving force calculating means is configured to set a vehicle yaw gain corresponding to a steering operation amount of a steering wheel as the desired vehicle yaw gain.   The braking / driving force calculating means includes a vehicle center-of-turn lateral force acting on the vehicle center of gravity in accordance with a braking / driving force difference between the left and right wheels in the front wheel and a vehicle center of gravity in accordance with a braking / driving force difference between the left and right wheels in the rear wheel. The steering device according to claim 1, 2 or 3, wherein the braking / driving force of the wheel is calculated so that the lateral force in the vehicle turning inward direction acting on the vehicle cancels out.   5. The braking / driving force calculating means is configured to obtain a driving force as a braking / driving force of a turning outer wheel and to obtain a braking force as a braking / driving force of an inner turning wheel. The steering apparatus described.

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