Vehicle control device and vehicle control method

Abstract

A disclosed vehicle control device (10) is provided with a sum model (M1) in which the motion states of a left drive system and a right drive system during straight travel are modeled, a difference model (M2) in which the motion states of the left drive system and the right drive system during turning are modeled, a calculation unit (11), a limiting unit (12), and a control unit (13). The calculation unit (11) calculates a sum mode target slip ratio (yS) and a difference mode target slip ratio (yD). The limiting unit (12) sets respective upper limit values (ySH, yDH) and lower limit values (ySL, yDL) for the sum mode target slip ratio (yS) and the difference mode target slip ratio (yD), and limits the target slip ratios (yS, yD). The control unit (13) controls the driving forces of the left drive system and the right drive system on the basis of the sum mode target slip ratio (yS) and the difference mode target slip ratio (yD) after the limitations, the sum model (M1), and the difference model (M2).

Description

Vehicle control device and vehicle control method

[0001] The present invention relates to a vehicle control device and a vehicle control method for controlling the driving force of a vehicle.

[0002] Conventionally, there is known a vehicle equipped with a mechanism capable of adjusting the drive force of each of the left and right wheels, which controls each drive force so as to suppress torsional vibration of the left and right wheels (see Patent Document 1).Also known is a vehicle that sets a target slip ratio for each of the left and right wheels and controls the drive force of each of the left and right wheels so that the actual slip ratio becomes the target slip ratio (see Patent Document 2).

[0003] JP 2019-103249 A International Publication No. 2023 / 013565

[0004] The larger the target slip ratio is set, the greater the actual slip ratio becomes, and the less driving force is transmitted to the road surface. Therefore, to improve the vehicle's driving stability, it is desirable to keep the target slip ratio within a predetermined range. However, if the range of possible target slip ratios is fixed, there is a problem in that the longitudinal and lateral forces of the wheels (tire limits) cannot be efficiently utilized in driving force control.

[0005] For example, in driving force control using a sum-mode target slip ratio corresponding to the sum of the target slip ratios of the left and right wheels and a differential-mode target slip ratio corresponding to the difference between the target slip ratios, the smaller the sum-mode target slip ratio, the greater the margin of the differential-mode target slip ratio relative to the tire limit, allowing for a setting that increases the differential-mode target slip ratio. Similarly, the smaller the differential-mode target slip ratio, the greater the margin of the sum-mode target slip ratio relative to the tire limit, allowing for a setting that increases the sum-mode target slip ratio. Conventional driving force control does not take such characteristics into account, leaving room for improvement.

[0006] One of the objectives of the present invention was invented in light of the above-mentioned problems, and is to provide a vehicle control device and a vehicle control method that enable efficient use of longitudinal and lateral forces of wheels in driving force control. In addition to this objective, another objective of the present invention is to achieve effects derived from the configurations shown in the "Mode for Carrying Out the Invention" described below, which are not obtainable with conventional technologies.

[0007] The disclosed invention can be realized as the following disclosed embodiments (application examples) and solves at least part of the above-mentioned problems. Each embodiment from embodiment 2 onwards is an embodiment that can be selected as an additional embodiment, and each embodiment can be omitted. None of the embodiments from embodiment 2 onwards discloses an embodiment or configuration that is essential to the present invention.

[0008] Aspect 1. The disclosed vehicle control device is a vehicle control device that controls the driving forces of a left drive system and a right drive system in a vehicle that has a left drive system including a left axle and left wheels to which power from a left drive source is transmitted, and a right drive system including a right axle and right wheels to which power from a right drive source is transmitted. This vehicle control device includes a sum model that models the motion states of the left drive system and the right drive system when traveling straight, and a difference model that models the motion states of the left drive system and the right drive system when turning. This vehicle control device also includes a calculation unit, a limiting unit, and a control unit.

[0009] The calculation unit calculates a sum mode target slip ratio corresponding to the sum of target slip ratio values ​​for the left and right wheels and a difference mode target slip ratio corresponding to the difference between the target slip ratio values. The limiting unit sets upper and lower limits for the sum mode target slip ratio and the difference mode target slip ratio to limit the sum mode target slip ratio and the difference mode target slip ratio. The control unit controls the drive forces of the left drive system and the right drive system based on the sum mode target slip ratio and the difference mode target slip ratio after limiting by the limiting unit, the sum model, and the difference model.

[0010] Aspect 2. In an aspect including the above-described aspect 1, it is preferable that the limiting unit sets the upper limit and the lower limit based on the actual slip ratios of the left wheel and the right wheel. Aspect 3. In an aspect including the above-described aspect 2, it is preferable that the limiting unit sets the upper limit and the lower limit of the sum mode target slip ratio based on a differential mode actual slip ratio, which is the actual slip ratio of the differential model corresponding to the difference between the actual slip ratios of the left wheel and the right wheel.

[0011] Aspect 4. In an aspect including the above-mentioned Aspect 2, it is preferable that the limiting unit sets the upper limit and lower limit of the difference mode target slip ratio based on a sum mode actual slip ratio, which is the actual slip ratio of the sum model corresponding to the sum of the actual slip ratios of the left wheel and the right wheel. Aspect 5. In an aspect including the above-mentioned Aspect 1, it is preferable that the limiting unit sets the upper limit and lower limit based on the target slip ratios of the left wheel and the right wheel.

[0012] Aspect 6. In aspects including the above-described Aspect 1, it is preferable that the limiting unit sets the upper limit value and the lower limit value based on the required driving force of the vehicle. Aspect 7. In aspects including the above-described Aspect 6, it is preferable that the limiting unit sets the upper limit value and the lower limit value based on a driving force ratio that is the ratio between a sum mode required driving force corresponding to the sum of the required driving forces of the left wheel and the right wheel, and a difference mode required driving force corresponding to the difference between the required driving forces of the left wheel and the right wheel.

[0013] Aspect 8. In aspects including Aspect 7 above, it is preferable that the limiting unit makes the upper limit ratio, which is the ratio between the upper limit of the sum mode target slip ratio and the upper limit of the difference mode target slip ratio, proportional to the driving force ratio. Aspect 9. In aspects including Aspect 8 above, it is preferable that the limiting unit changes the proportionality constant of the upper limit ratio to the driving force ratio in accordance with the running state of the vehicle or an operation by the driver.

[0014] Aspect 10. The disclosed vehicle control method is a vehicle control method for controlling the driving forces of a left drive system and a right drive system in a vehicle equipped with a left drive system including a left axle and left wheels to which power from a left drive source is transmitted, and a right drive system including a right axle and right wheels to which power from a right drive source is transmitted. First, a sum model that models the motion states of the left drive system and the right drive system when traveling straight, and a difference model that models the motion states of the left drive system and the right drive system when turning are prepared.

[0015] A sum mode target slip ratio corresponding to the sum of target slip ratio values ​​for the left and right wheels and a differential mode target slip ratio corresponding to the difference between the target slip ratio values ​​are calculated. Upper and lower limits are set for the sum mode target slip ratio and the differential mode target slip ratio to limit the sum mode target slip ratio and the differential mode target slip ratio. The drive forces of the left drive system and the right drive system are controlled based on the limited sum mode target slip ratio and the differential mode target slip ratio, the sum model, and the differential model.

[0016] According to the disclosed vehicle control device and vehicle control method, by setting upper and lower limit values ​​for each of the sum mode target slip ratio and the difference mode target slip ratio, it is possible to set target slip ratios that efficiently utilize the longitudinal and lateral forces of the wheels.

[0017] 6A and 6B are graphs illustrating a method for setting an upper limit value of a differential mode target slip ratio based on a sum mode actual slip ratio; and FIG. 6B is a graph illustrating a method for setting an upper limit value of a sum mode target slip ratio based on a differential mode actual slip ratio. (A) is a graph illustrating a method for setting an upper limit value of a sum mode target slip ratio based on a differential mode actual slip ratio. (A) and (B) are graphs illustrating a method for setting an upper limit value of a sum mode target slip ratio and an upper limit value of a differential mode target slip ratio based on a required driving force of the vehicle. (A) is a graph illustrating the relationship between an actual slip ratio and a longitudinal force during cornering for a plurality of sideslip angles, and (B) is a graph illustrating the relationship between an actual slip ratio and a lateral force during cornering for a plurality of sideslip angles.

[0018] The types of vehicles in which the disclosed vehicle control device and vehicle control method are used include, for example, engine vehicles (gasoline vehicles, diesel vehicles), electric vehicles, and hybrid vehicles. The disclosed invention relates to a vehicle equipped with a mechanism capable of adjusting the driving force of at least the left and right wheels (in other words, the left and right wheels, i.e., the left and right drive wheels), and the type and number of drive sources (internal combustion engine, motor, etc.) are not important.

[0019] The disclosed invention is preferably applied to an automobile that runs by driving left and right wheels (left and right drive wheels) using multiple drive sources. Here, one of the multiple drive sources is referred to as the left drive source, and the other drive source is referred to as the right drive source. Furthermore, of the left and right wheels, one located on the left side of the vehicle is referred to as the left wheel, and the other is referred to as the right wheel. The disclosed vehicle control device and vehicle control method can be used to control a vehicle that has a left drive system including a left axle and left wheel to which power is transmitted from the left drive source, and a right drive system including a right axle and right wheel to which power is transmitted from the right drive source.

[0020] The layout of each of the left and right drive sources may or may not correspond to the left-right direction defined based on the vehicle's direction of travel. Furthermore, the left and right drive systems may operate independently of each other, or may be connected to each other via a transmission mechanism or a power distribution mechanism. The disclosed vehicle control device and vehicle control method can be used to control in-wheel motor vehicles in which the left and right wheels are driven by individual motors, as well as torque vectoring vehicles in which the left and right wheels can transmit driving force or torque to each other.

[0021] [1. Configuration] A vehicle control device 10 according to an embodiment is mounted on a vehicle 1 shown in FIG. 1. The vehicle 1 includes left and right wheels 5 (wheels) arranged side by side in the vehicle width direction, a power distribution mechanism 3 (differential mechanism) that applies a torque difference to the left and right wheels 5, and a pair of motors 2 connected to the power distribution mechanism 3. In the drawings of the embodiment, the letters L and R added to the numeral symbols indicate the location of the element associated with the symbol (whether it is on the left or right side of the vehicle 1). For example, 5L indicates one of the left and right wheels 5 located on the left side of the vehicle 1 (the left wheel), and 5R indicates the other wheel located on the right side (the right wheel). The positions of the left and right wheels 5 in the fore-and-aft direction are not important, and they may be the front or rear wheels of the vehicle 1.

[0022] The motor 2 (drive source) has the function of driving at least either the front wheels or the rear wheels of the vehicle 1, and can also have the function of driving all four wheels. Of the pair of motors 2, one located on the left side is the left motor 2L (left drive source), and the other located on the right side is the right motor 2R (right drive source). The left motor 2L and the right motor 2R operate independently of each other and can individually output drive forces of different magnitudes. These motors 2 are connected to the power distribution mechanism 3 via a pair of speed reduction mechanisms provided separately from each other.

[0023] The vehicle 1 is equipped with a power distribution mechanism 3 that amplifies the torque difference between the pair of motors 2 and distributes it to each of the left and right wheels 5. The power distribution mechanism 3 in this embodiment is a differential mechanism with a yaw control function (AYC (Active Yaw Control) function) and is interposed between an axle 4 (left axle 4L) connected to the left wheel 5L and an axle 4 (right axle 4R) connected to the right wheel 5R. The yaw control function actively controls the ratio of the driving force (driving torque) shared between the left and right wheels 5 to adjust the yaw moment and stabilize the posture of the vehicle 1. The power distribution mechanism 3 incorporates a planetary gear mechanism, a differential gear mechanism, and the like. A vehicle drive system including the pair of motors 2 and the power distribution mechanism 3 is also called a DM-AYC (Dual Motor AYC) system.

[0024] As shown in Figure 2, the power distribution mechanism 3 includes a pair of speed reduction mechanisms (gear trains surrounded by dashed lines in Figure 2) and a transmission mechanism (gear trains surrounded by dashed lines in Figure 2) that reduce the rotational speed of the motor 2. The speed reduction mechanism is a mechanism that increases the torque (driving force) output from the motor 2 by reducing the torque. The reduction ratio G of the speed reduction mechanism is set appropriately depending on the output characteristics and performance of the motor 2. If the torque performance of the motor 2 is sufficiently high, the speed reduction mechanism may be omitted. The transmission mechanism is a mechanism that amplifies the difference in torque transmitted to each of the left and right wheels 5.

[0025] The transmission mechanism of the power distribution mechanism 3 shown in FIG. 2 includes a pair of planetary gear mechanisms. These planetary gear mechanisms have a structure in which planetary gears provided on respective carriers and their rotation axes are connected to each other. Each carrier supports a planetary gear so that it can rotate and also supports the planetary gear so that it revolves around a sun gear. Furthermore, driving forces transmitted from the left and right motors 2 are input to the ring gear and sun gear of one planetary gear mechanism. Driving forces transmitted to the left and right wheels 5 are extracted from the sun gear and carrier of the other planetary gear mechanism. Note that the structure of the power distribution mechanism 3 shown in FIG. 2 is merely one example for achieving a yaw control function, and other known structures may also be used.

[0026] J in Figure 2 Ｍis the motor inertia (moment of inertia of motor 2), J ｗ represents the wheel inertia (moment of inertia of the left and right wheels 5). ＬＭ is the left motor input torque (left motor command torque), T Ｌｍ is the left motor input torque after deceleration by the reduction mechanism, ω ＬＭ is the left motor angular velocity, ω Ｌｍ is the angular velocity of the left motor after deceleration by the deceleration mechanism, T Ｌｉｎ is the torque on the left drive side, T Ｌｄｓ is the left axle torque, T ＬＬ is the left wheel load torque, ω Ｌｄｓ is the left driving side angular velocity, ω ＬＬ is the left wheel angular velocity (target velocity of the left wheel 5L). Similarly, for the parameters of the right drive system, T ＲＭ is the right motor input torque (right motor command torque), T Ｒｍ is the right motor input torque after deceleration by the reduction mechanism, ω ＲＭ is the right motor angular velocity, ω Ｒｍ is the angular velocity of the right motor after deceleration by the deceleration mechanism, T Ｒｉｎ is the right drive torque, T Ｒｄｓ is the right axle torque, T ＲＬ is the right wheel load torque, ω Ｒｄｓ is the right drive side angular velocity, ω ＲＬ is the right wheel angular velocity (target velocity of the right wheel 5R).

[0027] 3 is a velocity diagram of the power distribution mechanism 3. １ , b ２ represents the torque difference amplification factor (deceleration rate, differential reduction ratio) determined according to the structure of the gears built into the power distribution mechanism 3. The torque difference amplification factor related to the power transmission from the left motor 2L to the right wheel 5R is b １ The torque difference amplification factor for power transmission from the left motor 2L to the left wheel 5L is b １ +1. The torque difference amplification factor for power transmission from the right motor 2R to the left wheel 5L is b ２ The torque difference amplification factor for power transmission from the right motor 2R to the right wheel 5R is b ２ It's +1.

[0028] As shown in FIG. 1 , each of the pair of motors 2 is electrically connected to a battery 7 via an inverter 6 (6L, 6R). The inverter 6 is a converter (DC-AC inverter) that converts between power (DC power) from a DC circuit on the battery 7 side and power (AC power) from an AC circuit on the motor 2 side. The battery 7 is, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and is a secondary battery that can supply high-voltage DC current of several hundred volts. When the motor 2 is powered, the DC power is converted into AC power by the inverter 6 and supplied to the motor 2. When the motor 2 is generating power, the generated power is converted into DC power by the inverter 6 and charged into the battery 7. The operating state of the inverter 6 is controlled by a vehicle control device 10.

[0029] The vehicle control device 10 is one of the electronic control units (ECU) mounted on the vehicle 1. The vehicle 1 is equipped with a left drivetrain including a left axle 4L and a left wheel 5L to which power is transmitted from a left motor 2L (left drive source), and a right drivetrain including a right axle 4R and a right wheel 5R to which power is transmitted from a right motor 2R (right drive source).The vehicle control device 10 has a function of controlling the output of each of the left motor 2L and the right motor 2R.

[0030] The vehicle control device 10 incorporates a processor (central processing unit), memory (main memory), storage device, interface device, etc. (not shown), which are communicably connected to one another via an internal bus. The contents of the determinations and controls performed by the vehicle control device 10 are recorded and saved in the memory as firmware or application programs, and when the programs are executed, the contents of the programs are expanded in the memory space and executed by the processor.

[0031] The vehicle control device 10 is connected to an accelerator opening sensor 14, a brake sensor 15, a steering angle sensor 16, a resolver 17, and a wheel speed sensor 18. The accelerator opening sensor 14 is a sensor that detects the amount of depression of the accelerator pedal (accelerator opening) and the depression speed. The brake sensor 15 is a sensor that detects the amount of depression of the brake pedal (brake pedal stroke) and the depression speed. The steering angle sensor 16 is a sensor that detects the steering angle of the left and right wheels 5 (actual steering angle or steering angle of the steering wheel).

[0032] The resolvers 17 (17L, 17R) are sensors that detect the speed of the motors 2 and are individually provided for each of the pair of motors 2. The resolvers 17 output information on the rotation angle of the motors 2 as two-phase AC voltages. The speed of the motors 2 is determined from changes in these AC voltages over time. The wheel speed sensors 18 (18L, 18R) are sensors that detect the speed of the axles 4. The vehicle control device 10 controls the operating state of the inverters 6 (6L, 6R) based on the information detected by the various sensors 14 to 18, thereby controlling the output of the pair of motors 2 (2L, 2R). Note that instead of the resolvers 17, other sensors (such as hall sensors or encoders) with different internal structures or operating principles may be used.

[0033] 1, the vehicle control device 10 includes a sum model M1, a difference model M2, a calculation unit 11, a restriction unit 12, and a control unit 13 as elements for controlling the driving forces of the left and right drive trains. These elements are shown by conveniently classifying the functions of the vehicle control device 10. These elements may be written as independent programs for realizing the functions of each element. Alternatively, multiple elements may be combined and written as a single composite program.

[0034] The sum model M1 is a model that is created to grasp the motion states of the left drive system (the power transmission path from the left motor 2L to the left wheel 5L) and the right drive system (the power transmission path from the right motor 2R to the right wheel 5R) when the vehicle 1 is traveling straight. The parameters input to the sum model M1 correspond to the sum of the parameters input to the left drive system and the parameters input to the right drive system, and are called "sum model state quantities." The difference model M2 is a model that is created to grasp the motion states of the left drive system and the right drive system when the vehicle 1 is turning. The parameters input to the difference model M2 correspond to the difference between the parameters input to the left drive system and the parameters input to the right drive system, and are called "difference model state quantities."

[0035] The calculation unit 11 calculates a sum mode target slip ratio y Ｓ and the differential mode target slip ratio y, which is the target slip ratio of the differential model M2 corresponding to the difference between the target values ​​of each slip ratio. Ｄ The calculation unit 11 calculates the sum mode target slip ratio y based on, for example, the required driving force and the estimated driving force of the vehicle 1. Ｓ and difference mode target slip ratio y Ｄ The required driving force here includes the required torque, required rotation speed (required angular velocity), and required output (required horsepower, required power) related to the motor 2 and the left and right wheels 5, and the estimated driving force includes the estimated torque, estimated rotation speed (required angular velocity), and estimated output (estimated horsepower, estimated power) related to the motor 2 and the left and right wheels 5.

[0036] In the vehicle control device 10 of this embodiment, the left axle required torque T required for the left axle 4L is ＬＬ and the left axle estimated torque, which is the estimated value of the actual torque of the left axle 4L (left axle torque deviation), are calculated, and the right axle required torque T ＲＬand the right axle estimated torque, which is the estimated value of the actual torque of the right axle 4R (left axle torque deviation). In addition, the calculation unit 11 calculates a sum model torque deviation corresponding to the sum of the left axle torque deviation and the right axle torque deviation, and calculates a difference model torque deviation corresponding to the difference between the left axle torque deviation and the right axle torque deviation. Thereafter, the sum mode target slip ratio y Ｓ is calculated, and the differential mode target slip ratio y Ｄ is calculated.

[0037] The limiting unit 12 determines the sum mode target slip ratio y Ｓ and the differential mode target slip ratio y Ｄ Upper limit y ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ and the sum mode target slip ratio y calculated by the calculation unit 11 is set. Ｓ and the differential mode target slip ratio y Ｄ Each of these is set to the upper limit value y ＳＨ , y ＤＨ Less than or equal to lower limit y ＳＬ , y ＤＬ The sum mode target slip ratio y is set to 0. Ｓ Upper limit y ＳＨ and the lower limit y ＳＬ are values ​​that have the same absolute value and differ only in sign (y ＳＬ = -y ＳＨ ). Differential mode target slip ratio y Ｄ The upper limit y ＤＨ and the lower limit y ＤＬ The absolute values ​​are the same, and only the signs are different (y ＤＬ = -y ＤＨ ). The sum mode target slip ratio y Ｓ The upper limit y ＳＨ does not necessarily correspond to the differential mode target slip ratio y Ｄ The upper limit y ＤＨ and may be set to different values.

[0038] The control unit 13 calculates the sum mode target slip ratio y after the limiting unit 12 has limited the Ｓ and the differential mode target slip ratio yＤ The control unit 13 controls the driving forces of the left and right drive trains based on the sum model M1 and the difference model M2. Ｓ The sum mode command torque T obtained by applying Ｓ (sum mode required torque) and the difference mode target slip ratio y after limitation by the limiting unit 12 Ｄ The differential mode command torque T obtained by applying Ｄ (Differential mode required torque) is used to control the driving forces of the left and right drive trains. Ｓ and differential mode torque T Ｄ The left motor command torque T ＬＭ and right motor command torque T ＲＭ Then, the calculated left motor command torque T ＬＭ and right motor command torque T ＲＭ This makes it easier to accurately control the motion states of the left and right drive trains so that they are in the desired states.

[0039] 4 is a schematic diagram showing the structure of the left and right drive trains of the vehicle 1. Each of the left axle 4L and the right axle 4R has a spring (axle stiffness K ｓ ) and damper (axle viscous D ｓ ) can be considered as a structure in which the J in FIG. ＬＭ is the inertia of the power distribution mechanism 3 side (drive side) relative to the left axle 4L, J Ｌｗ is the inertia of the left wheel 5L (load side) relative to the left axle 4L, J ＲＭ is the inertia of the power distribution mechanism 3 side (drive side) relative to the right axle 4R, J Ｒｗ is the inertia of the right wheel 5R side (load side) relative to the right axle 4R. Also, in FIG. 4, the left driving side angular velocity ω Ｌｄｓ (left driving side angular acceleration), left wheel angular velocity ω ＬＬ (left wheel angular acceleration), right drive side angular velocity ω Ｒｄｓ (right drive side angular acceleration), right wheel angular velocity ω ＲＬ The differential value (right wheel angular acceleration) of

[0040] Based on the above schematic diagrams, the configuration of the sum model M1 can be modeled as shown in Fig. 5(A), and the configuration of the difference model M2 can be modeled as shown in Fig. 5(B). The sum model M1 is suitable for use in vibration damping control and slip control for the axles 4 and left and right wheels 5 related to the straight-line movement of the vehicle 1, and the difference model M2 is suitable for use in vibration damping control and slip control for the axles 4 and left and right wheels 5 related to the turning of the vehicle 1. In this embodiment, both the sum model M1 and the difference model M2 are two-inertia system models, but each may be configured as a multi-inertia system model consisting of three or more moments of inertia and spring dampers.

[0041] As shown in FIG. 5A, the sum model M1 is ＳＭ and rigidity K ｓ and viscosity D ｓ The spring damper is designed with the load side inertia (sum mode wheel nominal inertia) J ＳＬ Drive side inertia J ＳＭ is the inertia J of the drive sources (left drive source and right drive source) Ｍ For example, J ＳＭ = G ２ J Ｍ In addition, the load inertia J ＳＬ is calculated based on the vehicle weight M (wheel equivalent). ＳＭ and load inertia J ＳＬ Friction may also be taken into consideration when calculating the equation of motion for the sum model M1.

[0042]

[0043] As shown in FIG. 5B, the difference model M2 is the driving side inertia J ＤＭ and rigidity K ｓ and viscosity D ｓ The spring damper is designed with the load side inertia (differential mode wheel nominal inertia) J ＤＬ Drive side inertia J ＤＭ is the inertia J of the drive sources (left drive source and right drive source) Ｍ and the torque difference amplification factor (b１ , b ２ etc.), for example, J ＤＭ = (2b １ +1) ２ G ２ J Ｍ In addition, the load inertia J ＤＬ is calculated based on the yaw inertia (wheel equivalent) of the vehicle 1. ＤＭ and load inertia J ＤＬ Friction may also be taken into consideration when calculating the equation of motion for the differential model M2.

[0044]

[0045] By applying the sum model state quantity to the sum model M1, parameters representing the motion states of the left and right drive trains when the vehicle 1 is traveling straight are obtained. For example, if the sum model M1 is applied with a sum mode target slip ratio y Ｓ By applying Ｓ The same applies to the difference model M2, and by applying the difference model state quantity to the difference model M2, parameters representing the motion states of the left and right drive trains when the vehicle 1 is turning are obtained. For example, when the difference model M2 is applied with the difference mode target slip ratio y Ｄ By applying the differential mode command torque T Ｄ is obtained.

[0046] 6 is a block diagram showing a specific example of control by the vehicle control device 10. The vehicle control device 10 is provided with a slip setting unit 21 including a calculation unit 11 and a limiting unit 12, and a control unit 13 has the function of calculating control variables related to slip control of the vehicle 1. The control unit 13 is provided with a sum mode control unit 22, a difference mode control unit 23, and a left-right conversion unit 24. Inside the control unit 13, for example, a sum model M1 and a difference model M2 for slip control are prepared.

[0047] The vehicle control device 10 is also provided with a required driving force setting unit 51, an estimated driving force observer 52, a sum-difference conversion unit 53, a vibration damping control unit 54, and a left-right conversion unit 57. The vibration damping control unit 54 has the function of calculating a control amount related to vibration damping control (vibration suppression control) of the vehicle 1. Inside the vibration damping control unit 54, a sum model M1 and a difference model M2 for vibration damping control, which are different from the sum model M1 and difference model M2 for slip control, are prepared. Furthermore, in this vehicle control device 10, the sum of the control amount of slip control by the control unit 13 and the control amount of vibration damping control by the vibration damping control unit 54 is calculated as the final motor command torque T ＬＭ , T ＲＭ This becomes:

[0048] The required driving force setting unit 51 sets the driving force that the driver requests from the vehicle 1. Here, the required left axle torque T required for the left axle 4L is calculated based on, for example, the accelerator opening, the brake pedal stroke, the steering angle, the vehicle speed, etc. ＬＬ and the right axle required torque T required for the right axle 4R. ＲＬ The left axle required torque T ＬＬ and right axle required torque T ＲＬ The information is transmitted to the sum-difference converter 53 .

[0049] The estimated driving force observer 52 calculates an estimated value corresponding to the actual driving force of the vehicle 1. Here, the estimated value of the driving torque of the left axle 4L is calculated based on, for example, the motor command torque related to the control signal output to the inverter 6 in the immediately preceding control cycle, the motor angular velocity detected by the resolver 17, the wheel speed detected by the wheel speed sensor 18, etc. ＬＬ ' and the estimated right axle torque T ＲＬ The vehicle control device 10 calculates the left axle required torque T ＬＬ Left axle estimated torque T ＬＬ The left axle torque deviation subtracted from ' and the right axle required torque T ＲＬ to the right axle estimated torque T ＲＬ The information on the left axle torque deviation and the right axle torque deviation calculated here is transmitted to the calculation unit 11 of the slip setting unit 21.

[0050] The sum / difference conversion unit 53 converts the left axle required torque T ＬＬ and right axle required torque T ＲＬ The sum mode torque and the difference mode torque are calculated. The value of the sum mode torque is, for example, the left axle required torque T ＬＬ and right axle required torque T ＲＬ The information on the sum mode torque is transmitted to the sum mode control section 55 of the vibration suppression control section 54. The value of the difference mode torque is, for example, half the sum of the left axle required torque T ＬＬ and right axle required torque T ＲＬ The information on the differential mode torque is transmitted to the differential mode control section 56 of the vibration suppression control section 54.

[0051] Sum mode control unit 55 applies the sum mode torque calculated by sum-difference conversion unit 53 to sum model M1 for vibration suppression control, thereby calculating sum mode torque in which vibrations that may occur when vehicle 1 travels straight (for example, sum-mode corresponding vibrations of several to several dozen hertz) are suppressed. Furthermore, difference mode control unit 56 applies the difference mode torque calculated by sum-difference conversion unit 53 to difference model M2 for vibration suppression control, thereby calculating difference mode torque in which vibrations that may occur when vehicle 1 turns (for example, vibrations with a lower frequency than sum-mode corresponding vibrations) are suppressed.

[0052] The left / right conversion unit 57 performs a calculation to allocate the sum mode torque obtained by the sum mode control unit 55 and the difference mode torque obtained by the difference mode control unit 56 to the left and right motors 2. Here, the command torque for vibration suppression control to be borne by each of the left motor 2L and the right motor 2R is calculated by a calculation equivalent to the inverse calculation of the sum / difference conversion unit 53. For example, the sum of the sum mode torque obtained by the sum mode control unit 55 and the difference mode torque obtained by the difference mode control unit 56 is used as the left motor command torque for vibration suppression control. Also, the difference between the sum mode torque obtained by the sum mode control unit 55 and the difference mode torque obtained by the difference mode control unit 56 is used as the right motor command torque for vibration suppression control.

[0053] The slip setting unit 21 sets parameters related to the target slip ratios of the left and right wheels 5. Fig. 7 is a block diagram showing a specific example of control by the slip setting unit 21. The slip setting unit 21 includes the above-mentioned calculation unit 11, limiting unit 12, left / right calculation unit 36, multipliers 37, 38, and sum / difference calculation unit 39. The calculation unit 11 includes a sum / difference calculation unit 31, a sum mode target slip ratio calculation unit 32, and a difference mode target slip ratio calculation unit 33. The limiting unit 12 also includes an upper / lower limit setting unit 40, a sum mode target slip ratio limiting unit 34, and a difference mode target slip ratio limiting unit 35.

[0054] The sum / difference calculation unit 31 calculates a sum model torque deviation corresponding to the sum of the left axle torque deviation and the right axle torque deviation, and a difference model torque deviation corresponding to the difference between the left axle torque deviation and the left axle torque deviation. The value of the sum model torque deviation is, for example, half the sum of the left axle torque deviation and the right axle torque deviation. Information about the sum model torque deviation is transmitted to a sum mode target slip ratio calculation unit 32. Furthermore, the value of the difference model torque deviation is, for example, half the difference between the left axle torque deviation and the right axle torque deviation. Information about the difference model torque deviation is transmitted to a difference mode target slip ratio calculation unit 33.

[0055] The sum mode target slip ratio calculation unit 32 calculates a sum mode target slip ratio y , which corresponds to the sum of the target values ​​of the slip ratios of the left wheel 5L and the right wheel 5R. Ｓ Here, the sum mode target slip ratio y is calculated based on the required driving force and estimated driving force of the vehicle 1. Ｓ For example, the sum mode target slip ratio y is calculated based on the integrated value of the difference (error) between the required driving force and the estimated driving force. Ｓ In this embodiment, the sum mode target slip ratio y is calculated based on the integrated value of the sum model torque deviation. Ｓ The sum mode target slip ratio y Ｓ The information is transmitted to the sum mode target slip ratio limiting section 34 .

[0056] The differential mode target slip ratio calculation unit 33 calculates a differential mode target slip ratio y ＤHere, the differential mode target slip ratio y is calculated based on the required driving force and estimated driving force of the vehicle 1. Ｄ For example, the differential mode target slip ratio y is calculated based on the integrated value of the difference (error) between the required driving force and the estimated driving force. Ｄ In this embodiment, the differential mode target slip ratio y is calculated based on the integrated value of the differential model torque deviation. Ｄ The calculated differential mode target slip ratio y Ｄ The information is transmitted to the differential mode target slip ratio limiting section 35 .

[0057] The upper and lower limit setting unit 40 determines the sum mode target slip ratio y Ｓ and the differential mode target slip ratio y Ｄ The upper limit value y for each ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ Here, for example, the limited sum mode target slip ratio y Ｓ and the differential mode target slip ratio y Ｄ The upper limit value y of each wheel is set so that it falls within the slip ratio range simulating the tire limit of the left wheel 5L and the right wheel 5R. ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ is set. Note that the upper limit value y ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ The value is preferably set within a slip ratio range that simulates the tire limit, but it can also be set to a value that exceeds the slip ratio range to the extent that the stability of the vehicle 1 is maintained.

[0058] These upper limits y ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬmay be set based on the actual slip ratios of the left wheel 5L and the right wheel 5R (parameters corresponding to the actual slip ratios). Alternatively, they may be set based on the target slip ratios of the left wheel 5L and the right wheel 5R (parameters corresponding to the target slip ratios) instead of the actual slip ratios (parameters corresponding to the actual slip ratios). Alternatively, they may be set based on the required driving force of the vehicle 1 (parameters corresponding to the required driving force).

[0059] For example, the upper limit value y ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ is the sum mode actual slip ratio λ Ｓ and difference mode actual slip ratio λ Ｄ The sum mode actual slip ratio λ may be set based on the following equation. Ｓ is a parameter corresponding to the sum of the actual slip ratios of the left wheel 5L and the right wheel 5R, and is the actual slip ratio of the sum model M1. Similarly, the difference mode actual slip ratio λ Ｄ is a parameter corresponding to the difference between the actual slip ratios of the left wheel 5L and the right wheel 5R, and is the actual slip ratio of the difference model M2.

[0060] In addition, the upper limit value y ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ is the sum mode target slip ratio y calculated by the calculation unit 11 Ｓ Differential mode target slip ratio y Ｄ The limited sum mode target slip ratio y Ｓ and the differential mode target slip ratio y Ｄ Alternatively, the sum mode required driving force F Ｓ and differential mode required driving force F Ｄ and the sum mode command torque T Ｓ and differential mode torque T Ｄ It may be set based on

[0061] [3-1. Setting upper and lower limits based on actual slip ratio] Sum mode actual slip ratio λ Ｓ and the difference mode actual slip ratio λ ＤThe value of is calculated based on the following formula, for example: Ｒ is the actual slip ratio of the right wheel, and λ Ｌ is the actual slip ratio of the left wheel. The actual sum mode slip ratio λ Ｓ For example, the actual slip ratio λ of the right wheel Ｒ and left wheel actual slip ratio λ Ｌ The difference mode actual slip ratio λ is half the sum of Ｄ For example, the actual slip ratio λ of the right wheel Ｒ and left wheel actual slip ratio λ Ｌ The actual slip ratio of the right wheel λ Ｒ , left wheel actual slip ratio λ Ｌ is, for example, a value obtained by dividing the absolute value of the difference between a reference wheel speed (vehicle speed in the vicinity of each wheel) and the actual wheel speed for each wheel by the reference wheel speed. The reference wheel speed is calculated based on, for example, the vehicle speed at the center of gravity of the vehicle, the yaw rate, vehicle specifications, etc.

[0062]

[0063] [A] Sum mode priority logic. Ｓ Based on the difference mode target slip ratio y Ｄ Upper limit y ＤＨ 10 is a graph illustrating a method for setting the sum mode target slip ratio y Ｓ Upper limit y ＳＨ is a first predetermined value y １ The difference mode target slip ratio y Ｄ Upper limit y ＤＨ is the sum mode target slip ratio y Ｓ and the differential mode target slip ratio y Ｄ is set so that it falls within the region surrounded by the solid line graph and the X and Y axes in Figure 8(A). This region corresponds to the first quadrant of the "slip ratio range simulating the tire limits of the left wheel 5L and the right wheel 5R" mentioned above.

[0064] first predetermined value y １ is the sum mode target slip ratio y Ｓ is a value that is preset as the maximum value that can be taken by y １ ≦1). third predetermined value y３ is the differential mode target slip ratio y Ｄ is a value that is provisionally set as the maximum value that can be taken by y ３ ≦1). second predetermined value y ２ is the differential mode target slip ratio y Ｄ is the maximum value (y ３ ) when the sum mode target slip ratio y Ｓ is a value that is preset as the maximum value that can be taken by y ２ ≦y １ ). Fourth predetermined value y ４ is the sum mode target slip ratio y Ｓ is the maximum value (y １ ) when the difference mode target slip ratio y Ｄ is a value that is preset as the maximum value that can be taken by y ４ ≦y ３ ).

[0065] The second predetermined value y ２ , fourth predetermined value y ４ When both the second predetermined value y and the second predetermined value y are not 0, the shape of the area surrounded by the graph indicated by the solid line and the X and Y axes is a pentagon (home plate shape), as shown in FIG. ２ , fourth predetermined value y ４ If only one of the second predetermined value y is 0, the shape of the area surrounded by the graph indicated by the solid line and the X and Y axes will be a rectangle (trapezoid). ２ , fourth predetermined value y ４ When both are 0, the shape of the area enclosed by the graph indicated by the solid line and the X and Y axes is triangular.

[0066] The upper and lower limit setting unit 40 assumes a point moving on the graph shown by the solid line in FIG. 8A, and calculates the sum mode actual slip ratio λ Ｓ The value of the Y coordinate of the point corresponding to the difference mode target slip ratio y Ｄ Upper limit y ＤＨ For example, the sum mode actual slip ratio λ Ｓ is the second predetermined value y ２ If it is less than the third predetermined value y ３ The upper limit value y ＤＨ The sum mode actual slip ratio λ Ｓ is the second predetermined value y２ The first predetermined value y １ If it is less than y, the upper limit of the magnitude according to the gradient of the graph is ＤＨ The sum mode actual slip ratio λ is output. Ｓ is the first predetermined value y １ If it is equal to or greater than the fourth predetermined value y ４ The upper limit value y ＤＨ The differential mode target slip ratio y Ｄ The lower limit y ＤＬ is the upper limit y ＤＨ and are negative values ​​with the same absolute value.

[0067] With this setting, the sum mode actual slip ratio λ Ｓ The smaller the difference mode target slip ratio y Ｄ Upper limit y ＤＨ increases, and the differential mode target slip ratio y Ｄ In addition, the sum mode actual slip ratio λ Ｓ The larger the difference mode target slip ratio y Ｄ Upper limit y ＤＨ decreases, and the differential mode target slip ratio y Ｄ Therefore, the longitudinal force and lateral force of the wheels are efficiently utilized in the driving force control.

[0068] Sum mode actual slip ratio λ Ｓ The difference mode target slip ratio y based on Ｄ Upper limit y ＤＨ The calculation formula for setting is shown below.

[0069] [B] Differential Mode Priority Logic FIG. 8(B) shows the differential mode actual slip ratio λ Ｄ Based on the sum mode target slip ratio y Ｓ Upper limit y ＳＨ 10 is a graph illustrating a method for setting the differential mode actual slip ratio λ Ｄ Upper limit y ＤＨ is previously set to a third predetermined value y ３ The upper and lower limit setting unit 40 assumes that a point moves on the graph shown by the solid line in FIG. 8B, and the Y coordinate is set to the differential mode actual slip ratio λ ＤThe value of the X coordinate of the point corresponding to the sum mode target slip ratio y Ｓ Upper limit y ＳＨ Set as.

[0070] For example, the difference mode actual slip ratio λ Ｄ is the fourth predetermined value y ４ If it is less than the first predetermined value y １ The upper limit value y ＳＨ Also, the differential mode actual slip ratio λ Ｄ is the fourth predetermined value y ４ The third predetermined value y ３ If it is less than y, the upper limit of the magnitude according to the gradient of the graph is ＳＨ Outputs the actual slip ratio λ in differential mode. Ｄ is the third predetermined value y ３ If it is equal to or greater than the second predetermined value y ２ The upper limit value y ＳＨ The sum mode target slip ratio y Ｓ The lower limit y ＳＬ is the upper limit y ＳＨ and are negative values ​​with the same absolute value.

[0071] With this setting, the difference mode actual slip ratio λ Ｄ The smaller the sum mode target slip ratio y Ｓ Upper limit y ＳＨ increases, and the sum mode target slip ratio y Ｓ In addition, the difference mode actual slip ratio λ Ｄ The larger the sum mode target slip ratio y Ｓ Upper limit y ＳＨ decreases, and the sum mode target slip ratio y Ｓ Therefore, the longitudinal force and lateral force of the wheels are efficiently utilized in the driving force control.

[0072] Difference mode actual slip ratio λ Ｄ Sum mode target slip ratio y based on Ｓ Upper limit y ＳＨ The calculation formula for setting is shown below.

[0073] [3-2. Setting of upper and lower limits based on target slip ratio] The above sum mode actual slip ratio λＳ is the sum mode target slip ratio y Ｓ The difference mode actual slip ratio λ can be replaced by Ｄ is the differential mode target slip ratio y Ｄ The sum mode target slip ratio y Ｓ and the differential mode target slip ratio y Ｄ The value of may be a value calculated by the calculation unit 11 or may be a limited value output from the limiting unit 12.

[0074] For example, in the graph shown in FIG. 8A, the sum mode actual slip ratio λ Ｓ Instead of the sum mode target slip ratio y Ｓ By applying Ｄ Upper limit y ＤＨ In the graph shown in FIG. 8B, the difference mode actual slip ratio λ Ｄ Instead of the difference mode target slip ratio y Ｄ By applying Ｓ Upper limit y ＳＨ may be set.

[0075] [3-3. Setting of upper and lower limits based on required driving force] Sum mode required driving force F Ｓ and differential mode required driving force F Ｄ The value of the left wheel required driving force F Ｌ and the right wheel required driving force F Ｒ The sum mode required driving force F Ｓ The value of the left wheel required driving force F Ｌ and right wheel required driving force F Ｒ The differential mode required driving force F Ｄ The value of the left wheel required driving force F Ｌ and right wheel required driving force F Ｒ The left wheel required driving force F Ｌ and right wheel required driving force F Ｒ Each of these is calculated based on, for example, the accelerator opening, the brake pedal stroke, the steering angle, the vehicle speed, the road surface inclination, the yaw rate, and the like.

[0076] FIG. 9A shows the sum mode required driving force F Ｓ and differential mode required driving force F Ｄ Based on the sum mode target slip ratio y Ｓ The upper limit y ＳＨ and the differential mode target slip ratio y Ｄ The upper limit y ＤＨ 9A is a graph for explaining a method for setting the upper and lower limit setting unit 40. The upper and lower limit setting unit 40 sets the slope of the coordinate system shown in FIG. Ｓ Differential mode required driving force F Ｄ A straight line is assumed to be equal to the ratio of the driving force (driving force ratio) and passes through the origin. The X coordinate of the intersection of this straight line with the solid line in FIG. 9A is the sum mode target slip ratio y Ｓ The upper limit y ＳＨ and the Y coordinate of the intersection is set as the difference mode target slip ratio y Ｄ The upper limit y ＤＨ Here, the sum mode target slip ratio y Ｓ The upper limit y ＳＨ Difference mode target slip ratio y Ｄ The upper limit y ＤＨ If the upper limit value ratio is defined as the upper limit value ratio, the upper and lower limit setting unit 40 sets the two upper limit values ​​y so that the upper limit value ratio coincides with the driving force ratio. ＳＨ , y ＤＨ This means that the following is set.

[0077] With this setting, the differential mode required driving force F Ｄ The smaller the relative value of the sum mode target slip ratio y Ｓ The upper limit y ＳＨ As the difference mode target slip ratio y increases, Ｄ The upper limit y ＤＨ This reduces the sum mode target slip ratio y Ｓ It is more permissible to increase the difference mode target slip ratio y Ｄ is likely to be limited to small values.

[0078] Conversely, the differential mode required driving force F Ｄ The larger the relative difference mode target slip ratio yＤ Upper limit y ＤＨ As the sum mode target slip ratio y increases, Ｓ Upper limit y ＳＨ This reduces the differential mode target slip ratio y Ｄ It is more permissible to increase the sum mode target slip ratio y Ｓ In any case, it becomes possible to efficiently utilize the longitudinal force and lateral force of the wheels in the driving force control.

[0079] Sum mode required driving force F Ｓ and differential mode required driving force F Ｄ Upper limit value y based on ＳＨ , y ＤＨ The calculation formula for setting is shown below.

[0080] In the example shown in FIG. 9B, two upper limit values ​​y are set so that the upper limit value ratio is proportional to the driving force ratio. ＳＨ , y ＤＨ In this example, the upper limit value ratio is not perfectly equal to the driving force ratio, but is set so that the upper limit value ratio matches the product of a predetermined coefficient k (proportionality constant) and the driving force ratio. ＳＨ , y ＤＨ is set. As a result, the higher the driving force ratio, the higher the upper limit value ratio, and the lower the driving force ratio, the lower the upper limit value ratio. The value of coefficient k may be a fixed value set in advance, or may be a variable value that varies depending on the driving state of vehicle 1 and driver operation. The case where coefficient k has a value of 1 corresponds to the example shown in FIG. 9(A).

[0081] The upper and lower limit setting unit 40 calculates the sum mode required driving force F Ｓ Differential mode required driving force F Ｄ The sum mode target slip ratio y is assumed to be equal to the product of the ratio (driving force ratio) of the sum mode target slip ratio y and the driving force ratio y. The X coordinate of the intersection of this line with the solid line in FIG. 9B is assumed to be the sum mode target slip ratio y. Ｓ Upper limit y ＳＨ and the Y coordinate of the intersection is set as the difference mode target slip ratio y Ｄ Upper limit y ＤＨEven with this setting, it is possible to efficiently utilize the longitudinal and lateral forces of the wheels in the driving force control. Also, by changing the value of the coefficient k, the sum mode target slip ratio y Ｓ and difference mode target slip ratio y Ｄ The balance can be adjusted.

[0082] For example, when k is set to a value smaller than 1, the slope of the straight line in FIG. 9B becomes smaller. Ｓ Upper limit y ＳＨ becomes easier to increase, and the difference mode target slip ratio y Ｄ Upper limit y ＤＨ This allows for slip control that prioritizes acceleration / deceleration performance (straight-line driving performance). Note that if k is set to 0, the behavior will be similar to the sum mode priority logic described above.

[0083] Furthermore, when k is set to a value greater than 1, the slope of the straight line in FIG. 9B becomes steeper. Ｄ Upper limit y ＤＨ becomes easier to increase, and the sum mode target slip ratio y Ｓ Upper limit y ＳＨ This makes it possible to realize slip control that emphasizes turning performance (movement performance in the turning direction). Note that if k is set to infinity (the maximum value allowed for control), behavior will be similar to the difference mode priority logic described above.

[0084] Driving force ratio (F Ｄ / F Ｓ ) and the upper limit value y based on the coefficient k ＳＨ , y ＤＨ The calculation formula for setting is shown below.

[0085] [3-4. Setting of upper and lower limit values ​​based on required torque] The sum mode required driving force F Ｓ can be replaced with the sum mode torque, and the above differential mode required driving force F ＤThe values ​​of the sum mode torque and the difference mode torque used here may be values ​​calculated by the sum / difference conversion unit 53, or may be values ​​calculated by the left axle required torque T ＬＬ and right axle required torque T ＲＬ The value may be calculated based on the above.

[0086] For example, in the graph shown in FIG. 9A, a straight line is assumed to have a slope equal to the ratio of the difference mode torque to the sum mode torque (torque ratio) and pass through the origin. The X and Y coordinates of the intersection of this straight line and the solid line in FIG. 9A are set to the upper limit value y. ＳＨ , y ＤＨ Similarly, in the graph shown in FIG. 9B, the upper limit value ratio is proportional to the torque ratio, and the upper limit value y ＳＨ , y ＤＨ may be set.

[0087] The sum mode target slip ratio limiting unit 34 limits the sum mode target slip ratio y set by the upper / lower limit setting unit 40. Ｓ Upper limit y ＳＨ and the lower limit y ＳＬ Based on the information, the sum mode target slip ratio y Ｓ is the lower limit y ＳＬ to the upper limit y ＳＨ The sum mode target slip ratio y calculated by the calculation unit 11 (sum mode target slip ratio calculation unit 32) is limited to a range of y Ｓ The value of y is the upper limit ＳＨ If the value exceeds the upper limit y ＳＨ and output from the sum mode target slip ratio limiting unit 34. On the other hand, the sum mode target slip ratio y Ｓ The value of y is the lower limit ＳＬ If the value is less than the lower limit y ＳＬ and output from the sum mode target slip ratio limiting unit 34. Ｓ The value of y is the lower limit ＳＬ Greater than or equal to upper limit y ＳＨ If it is equal to or less than this value, the sum mode target slip ratio limiting section 34 outputs the value as is.

[0088] Similarly, the differential mode target slip ratio limiting section 35 limits the differential mode target slip ratio y Ｄ Upper limit y ＤＨ and the lower limit y ＤＬ Based on the information, the differential mode target slip ratio y Ｄ is the lower limit y ＤＬ to the upper limit y ＤＨ The differential mode target slip ratio y calculated by the calculation unit 11 (differential mode target slip ratio calculation unit 33) is limited to fall within the range of y Ｄ The value of y is the upper limit ＤＨ If the value exceeds the upper limit y ＤＨ and output from the differential mode target slip ratio limiting section 35. Conversely, the differential mode target slip ratio y Ｄ The value of y is the lower limit ＤＬ If the value is less than the lower limit y ＤＬ and output from the differential mode target slip ratio limiting section 35. Ｄ The value of y is the lower limit ＤＬ Greater than or equal to upper limit y ＤＨ If it is equal to or less than this value, the differential mode target slip ratio limiting section 35 outputs the value as is.

[0089] The left / right calculation unit 36 ​​calculates the sum mode target slip ratio y obtained by the sum mode target slip ratio limiting unit 34. Ｓ and the differential mode target slip ratio y obtained by the differential mode target slip ratio limiting section 35. Ｄ and the sum mode target slip ratio y Ｓ and difference mode target slip ratio y Ｄ The difference between these is the target slip ratio y of the right wheel 5R. Ｒ and transmitted to the multiplier 37. In addition, the sum mode target slip ratio y Ｓ and difference mode target slip ratio y Ｄ The sum of these is the target slip ratio y of the left wheel 5L. Ｌ and transmitted to the multiplier 38.

[0090] The multiplier 37 multiplies the target slip ratio y Ｒand the reference wheel speed of the right wheel 5R, and outputs the product to the sum / difference calculation unit 39. Similarly, the multiplier 38 multiplies the target slip ratio y Ｌ and the reference wheel speed of the left wheel 5L, and outputs the product to a sum / difference calculation unit 39. The sum / difference calculation unit 29 calculates a sum mode target wheel speed and a difference mode target wheel speed based on the two values ​​output from the multipliers 37 and 38. The sum mode target wheel speed is, for example, half the sum of the two values ​​output from the multipliers 37 and 38, and the difference mode target wheel speed is, for example, half the difference of the two values ​​output from the multipliers 37 and 38. Information about the sum mode target wheel speed is transmitted to a sum mode control unit 22 of the control unit 13, and information about the difference mode target wheel speed is transmitted to a difference mode control unit 23 of the control unit 13.

[0091] The sum mode control unit 22 calculates sum mode torque for optimizing the slip ratio when the vehicle 1 is traveling straight by applying the sum mode target wheel speed obtained by the slip setting unit 21 to the sum model M1 for slip control. The difference mode control unit 23 calculates difference mode torque for optimizing the slip ratio when the vehicle 1 is turning by applying the difference mode target wheel speed obtained by the slip setting unit 21 to the difference model M2 for slip control.

[0092] Similar to left / right conversion unit 57, left / right conversion unit 24 performs a calculation to allocate the sum mode torque obtained by sum mode control unit 22 and the difference mode torque obtained by difference mode control unit 23 to the left and right motors 2. For example, the sum of the sum mode torque and the difference mode torque is used as the left motor command torque for slip control, and the difference between the sum mode torque and the difference mode torque is used as the right motor command torque for slip control.

[0093] The sum of the left motor command torque for vibration suppression control obtained by the left-right conversion unit 57 and the left motor command torque for slip control obtained by the left-right conversion unit 24 is the final left motor command torque T ＬＭ Similarly, the right motor command torque for vibration suppression control obtained by the left-right conversion unit 57 and the right motor command torque for slip control obtained by the left-right conversion unit 24 are added together to obtain the final right motor command torque T ＲＭ This becomes:

[0094] [4. Effects] (1) The vehicle control device 10 of this embodiment controls the driving forces of the left and right drive systems in a vehicle 1 that has a left drive system including a left axle 4L and left wheel 5L to which power from a left motor 2L (left drive source) is transmitted, and a right drive system including a right axle 4R and right wheel 5R to which power from a right motor 2R (right drive source). The vehicle control device 10 includes a sum model M1 that models the motion states of the left and right drive systems when traveling straight, and a difference model M2 that models the motion states of the left and right drive systems when turning.

[0095] The vehicle control device 10 also includes a calculation unit 11, a restriction unit 12, and a control unit 13. The calculation unit 11 calculates a sum mode target slip ratio y Ｓ and the differential mode target slip ratio y, which corresponds to the difference between the target values ​​of each slip ratio. Ｄ The limiting unit 12 calculates the sum mode target slip ratio y Ｓ and the differential mode target slip ratio y Ｄ The upper limit value y of each ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ Set the sum mode target slip ratio y Ｓ and the differential mode target slip ratio y Ｄ The control unit 13 limits the sum mode target slip ratio y after the limiting unit 12 Ｓ and the differential mode target slip ratio y Ｄ The driving forces of the left and right drive trains are controlled based on the sum model M1 and the difference model M2.

[0096] With this configuration, as shown in, for example, FIG. 8(A) and FIG. 8(B), the sum mode target slip ratio y Ｓ and the differential mode target slip ratio y Ｄ This makes it easy to keep the sum mode target slip ratio y within the slip ratio range, and allows the target slip ratio to be set so that the longitudinal and lateral forces of the wheels are efficiently utilized. Ｓ and the differential mode target slip ratio y ＤThe upper limit value y of each wheel is set so that it falls within the slip ratio range simulating the tire limit of the left wheel 5L and the right wheel 5R. ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ As a result, the sum mode target slip ratio y Ｓ and the differential mode target slip ratio y Ｄ can be reliably kept within the slip ratio range.

[0097] Furthermore, according to the above configuration, the sum mode target slip ratio y Ｓ If the difference mode target slip ratio y Ｄ becomes smaller, and the sum mode target slip ratio y Ｓ If becomes smaller, the difference mode target slip ratio y Ｄ Therefore, the target slip ratios of the left and right wheels 5 can be changed comprehensively, and the controllability relating to the balance between the longitudinal force and the lateral force of the wheels can be improved. The balance between the longitudinal force and the lateral force will be described in detail below.

[0098] FIG. 10A is a graph showing the relationship between the actual slip ratio and the longitudinal force (the longitudinal component of the frictional force acting on the wheel (the circumferential component of the wheel)) when the vehicle 1 is turning. In FIG. 10A, four graphs are used to show the relationship between the actual slip ratio and the longitudinal force obtained when the magnitude of the sideslip angle, which changes depending on the steering angle, is changed in four stages. The thick solid line graph corresponds to a relatively small sideslip angle, and the thin dashed line graph corresponds to a relatively large sideslip angle. FIG. 10B is a graph showing the relationship between the actual slip ratio and the lateral force (the lateral component of the frictional force acting on the wheel (the component perpendicular to the circumferential direction of the wheel)) when the vehicle 1 is turning. FIG. 10B also shows four graphs corresponding to four stages of sideslip angle change.

[0099] As shown in FIG. 10A, when the side slip angle is relatively large during a turning state (for example, the thin broken line graph), the actual slip ratio is λ １ From λ ２ When the force is increased to F Ｘ１ From F Ｘ２On the other hand, as shown in FIG. 10B, the lateral force increases as the actual slip ratio increases to λ in a cornering state where the sideslip angle is relatively large (for example, the thin broken line graph). １ From λ ２ By increasing it to F Ｙ１ From F Ｙ２ decreases to.

[0100] Here, the longitudinal force F in FIG. Ｘ１ , F Ｘ２ When the points corresponding to λ are plotted as white circles in FIG. 10(B), the actual slip ratio λ １ From λ ２ It can be seen that the magnitude relationship between the longitudinal force and the lateral force is reversed by changing the actual slip ratio to λ １ When this condition is met, the lateral force is greater than the longitudinal force (F Ｘ１ <F Ｙ１ ) while the actual slip ratio is λ ２ When this occurs, the longitudinal force is greater than the lateral force (F Ｙ２ <F Ｘ２ ) has become.

[0101] Therefore, the sum mode target slip ratio y Ｓ Upper limit y ＳＨ Increase the lower limit y ＳＬ If the sum mode target slip ratio y is set to a small value, the absolute value of the actual slip ratio is allowed to be larger, which facilitates an increase in longitudinal force and a decrease in lateral force. Ｓ Upper limit y ＳＨ and the lower limit y ＳＬ By varying this, it becomes possible to change the balance between the longitudinal force and the lateral force of the wheels. As a result, for example, by depressing the accelerator pedal more, the driver can increase the actual slip ratio, thereby increasing the longitudinal force and decreasing the lateral force, and thus achieve the desired turning state (for example, a drift state) as the driver desires. Also, by depressing the accelerator pedal more, the actual slip ratio can be decreased, increasing the lateral force and decreasing the longitudinal force, allowing the driver to achieve the desired turning state (for example, a grip state) at will.

[0102] (2) The limiting unit 12 of this embodiment determines the upper limit value y based on the actual slip ratios of the left wheel 5L and the right wheel 5R. ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ As a result, the actual slip state of the left and right wheels 5 can be set within the upper limit value y ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ Therefore, it is possible to accurately set a target slip ratio that efficiently utilizes the longitudinal force and lateral force of the wheels, and it is possible to further improve the controllability relating to the balance between the longitudinal force and lateral force of the wheels.

[0103] (3) As shown in FIG. 8B, the limiting unit 12 of this embodiment uses the differential mode actual slip ratio λ , which is the actual slip ratio of the differential model M2 corresponding to the difference between the actual slip ratios of the left wheel 5L and the right wheel 5R. Ｄ Based on this, the sum mode target slip ratio y Ｓ The upper limit y ＳＨ and the lower limit y ＳＬ This allows the differential mode actual slip ratio λ Ｄ Sum mode target slip ratio y Ｓ This allows slip control that emphasizes turning performance (movement performance in the turning direction) to be realized.

[0104] (4) As shown in FIG. 8A, the limiting unit 12 of this embodiment uses a sum mode actual slip ratio λ , which is the actual slip ratio of the sum model M1 corresponding to the sum of the actual slip ratios of the left wheel 5L and the right wheel 5R. Ｓ Based on this, the differential mode target slip ratio y Ｄ The upper limit y ＤＨ and the lower limit y ＤＬ This allows the sum mode actual slip ratio λ Ｓ The difference mode target slip ratio y Ｄ This allows slip control that emphasizes acceleration / deceleration performance (straight-line driving performance) to be realized.

[0105] (5) The limiting unit 12 of this embodiment determines the upper limit value y based on the target slip ratios of the left wheel 5L and the right wheel 5R. ＳＨ , y ＤＨ and the lower limit y ＳＬ, y ＤＬ This allows the upper limit value y to be set without specifying the actual slip state of the left and right wheels 5. ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ Therefore, a target slip ratio that efficiently utilizes the longitudinal force and lateral force of the wheel can be set with high accuracy using a simple control configuration, and controllability relating to the balance between the longitudinal force and lateral force of the wheel can be further improved.

[0106] (6) As shown in FIG. 9A, the limiting unit 12 of this embodiment determines the upper limit value y ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ As a result, the actual driving force transmitted to the left and right wheels 5 can be controlled to the upper limit value y ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ Therefore, it is possible to accurately set a target slip ratio that efficiently utilizes the longitudinal force and lateral force of the wheels, and it is possible to further improve the controllability relating to the balance between the longitudinal force and lateral force of the wheels.

[0107] (7) The limiting unit 12 of this embodiment limits the sum mode required driving force F , which corresponds to the sum of the required driving forces of the left wheel 5L and the right wheel 5R. Ｓ and a differential mode required driving force F corresponding to the difference between the required driving forces of the left wheel 5L and the right wheel 5R. Ｄ The upper limit value y is determined based on the driving force ratio, which is the ratio of ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ This allows the driving force ratio to be set to the upper limit value y ＳＨ , y ＤＨ and the lower limit y ＳＬ , y ＤＬ Therefore, it is possible to accurately set a target slip ratio that efficiently utilizes the longitudinal force and lateral force of the wheels, and it is possible to further improve the controllability relating to the balance between the longitudinal force and lateral force of the wheels.

[0108] (8) The limiting unit 12 of this embodiment, for example, as shown in FIG. 9B, Ｓ The upper limit y ＳＨ and difference mode target slip ratio y Ｄ The upper limit y ＤＨ The upper limit ratio, which is the ratio between the driving force ratio and the acceleration / deceleration performance (straight-line driving performance), can be made proportional to the driving force ratio. In this case, the characteristics (flavor) of the slip control can be changed according to the coefficient k, which corresponds to the proportionality constant. For example, by setting the coefficient k to a small value, slip control that emphasizes acceleration / deceleration performance (straight-line driving performance) can be realized. Also, by setting the coefficient k to a large value, slip control that emphasizes cornering performance (straight-line driving performance) can be realized.

[0109] (9) Furthermore, the limiting unit 12 of this embodiment can change the proportionality constant k of the upper limit value ratio to the driving force ratio in response to the driving state of the vehicle 1 or the driver's operation. This allows the characteristics (seasoning) of the slip control to be changed in response to the driving state or the driver's operation, thereby further improving controllability and convenience.

[0110] [5. Other] The above-described embodiments are merely illustrative and are not intended to exclude various modifications or applications of techniques not explicitly described in the present embodiments. Each configuration of the present embodiments can be modified in various ways without departing from the spirit of the present embodiments. Furthermore, each configuration of the present embodiments can be selected or combined as needed.

[0111] In the above embodiment, the vehicle control device 10 is applied to the rear wheels of the vehicle 1, but a similar vehicle control device may be applied to the front wheels, or to both the front and rear wheels. By implementing control similar to that of the above embodiment in a vehicle 1 equipped with a vehicle control device 10 that controls at least the driving forces of the left and right drive trains, it is possible to achieve the same effects as those of the above embodiment.

[0112] In the above embodiment, the sum mode required driving force F Ｓ Differential mode required driving force F Ｄ The ratio of the above is defined as the driving force ratio, but the differential mode required driving force F Ｄ Sum mode required driving force F ＳIn this case, the upper limit ratio may be defined as "differential mode target slip ratio y Ｄ Upper limit y ＤＨ Sum mode target slip ratio y Ｓ Upper limit y ＳＨ 9A and 9B can be realized. In the above embodiment, the control targeting the slip ratio has been described in detail, but the speed difference between the vehicle body and the wheels (for example, the difference between the reference vehicle body speed and the wheel speed) may be controlled instead of the slip ratio.

[0113] In realizing the vehicle control device according to the present invention, the driving force control methods described in the following reference documents can be referred to: ・Hiroshi Fujimoto, Takeshi Takano, Hidetoshi Nobumoto, Toshimi Okazaki, "Driving Force Control Technology Using High-Precision Slip Ratio Control," Mazda Technical Report, No. 32, pp. 228-233 (2015) ・Hiroshi Fujimoto, Junya Amada, Takayuki Miyajima, "Development and Control of an Electric Vehicle with a Variable Drive Unit System," Proceedings of the 2013 Society of Automotive Engineers of Japan Spring Academic Conference, No. 8-13, pp. 17-20 (2013) ・Masaki Yoshimura, Hiroshi Fujimoto, "Driving Torque Control Method for an Electric Vehicle Equipped with an In-Wheel Motor," Transactions of the Institute of Electrical Engineers of Japan, Vol. 131, No. 5, pp. 721-728 (2011)

[0114] The present invention is applicable to the manufacturing industry of vehicle control devices mounted on vehicles, and also applicable to the manufacturing industry of vehicles on which vehicle control devices are mounted.

[0115] REFERENCE SIGNS LIST 1 vehicle 2 motor 3 power distribution mechanism 4 axle 4L left axle 4R right axle 5 left and right wheels 5L left wheel 5R right wheel 6 inverter 7 battery 10 vehicle control device 11 calculation unit 12 limiting unit 13 control unit 14 accelerator opening sensor 15 brake sensor 16 steering angle sensor 17 resolver 18 wheel speed sensor 21 slip setting unit 22 sum mode control unit 23 difference mode control unit 24 left and right conversion unit 31 sum and difference calculation unit 32 sum mode target slip ratio calculation unit 33 difference mode target slip ratio calculation unit 34 sum mode target slip ratio limiting unit 35 difference mode target slip ratio limiting unit 36 ​​left and right calculation unit 37 multiplier 38 multiplier 39 sum and difference calculation unit 40 upper and lower limit setting unit 51 required driving force setting unit 52 Estimated driving force observer 53 Sum / difference conversion unit 54 Vibration suppression control unit 55 Sum mode control unit 56 Difference mode control unit 57 Left / right conversion unit M1 Sum model M2 Difference model y Ｓ Sum mode target slip ratio y Ｄ Differential mode target slip ratio

Claims

1. A vehicle control device for controlling each driving force of a left drive system and a right drive system including a left axle and a left wheel to which power from a left drive source is transmitted, and a right drive system including a right axle and a right wheel to which power from a right drive source is transmitted, comprising: a sum model that models the motion state of the left drive system and the right drive system when traveling straight; a difference model that models the motion state of the left drive system and the right drive system when turning; a calculation unit that calculates a sum mode target slip ratio corresponding to the sum of target values ​​of each slip ratio of the left wheel and the right wheel and a difference mode target slip ratio corresponding to the difference between the target values ​​of each slip ratio; a limiting unit that sets upper and lower limits of the sum mode target slip ratio and the difference mode target slip ratio to limit the sum mode target slip ratio and the difference mode target slip ratio; and a control unit that controls each driving force of the left drive system and the right drive system based on the sum mode target slip ratio and the difference mode target slip ratio after limitation by the limiting unit, the sum model, and the difference model. A vehicle control device.

2. The vehicle control device according to claim 1, wherein the limiting unit sets the upper limit value and the lower limit value based on actual slip ratios of the left wheel and the right wheel.

3. A vehicle control device as claimed in claim 2, characterized in that the limiting unit sets the upper limit and the lower limit of the sum mode target slip ratio based on a differential mode actual slip ratio, which is an actual slip ratio of the differential model corresponding to the difference between the actual slip ratios of the left wheel and the right wheel.

4. A vehicle control device as claimed in claim 2, characterized in that the limiting section sets the upper limit and the lower limit of the difference mode target slip ratio based on a sum mode actual slip ratio, which is an actual slip ratio of the sum model corresponding to the sum of the actual slip ratios of the left and right wheels.

5. The vehicle control device according to claim 1, wherein the limiting unit sets the upper limit value and the lower limit value based on target slip ratios of the left wheel and the right wheel.

6. The vehicle control device according to claim 1, wherein the limiting unit sets the upper limit value and the lower limit value based on a required driving force of the vehicle.

7. A vehicle control device as described in claim 6, characterized in that the limiting section sets the upper limit value and the lower limit value based on a driving force ratio which is a ratio between a sum mode required driving force equivalent to the sum of the required driving forces at the left wheel and the right wheel, and a difference mode required driving force equivalent to the difference between the required driving forces at the left wheel and the right wheel.

8. A vehicle control device according to claim 7, wherein the limiting section makes an upper limit ratio, which is the ratio between the upper limit value of the sum mode target slip ratio and the upper limit value of the difference mode target slip ratio, proportional to the driving force ratio.

9. The vehicle control device according to claim 8, wherein the limiting section changes a proportional constant of the upper limit value ratio to the driving force ratio in response to a driving state of the vehicle or an operation by a driver.

10. A vehicle control method for controlling the driving forces of a left drive system and a right drive system in a vehicle having a left drive system including a left axle and left wheel to which power from a left drive source is transmitted, and a right drive system including a right axle and right wheel to which power from a right drive source is transmitted, comprising the steps of: preparing a sum model that models the motion states of the left drive system and the right drive system when traveling straight, and a difference model that models the motion states of the left drive system and the right drive system when turning; calculating a sum mode target slip ratio corresponding to the sum of target values ​​of the slip ratios of the left wheel and the right wheel, and a difference mode target slip ratio corresponding to the difference between the target values ​​of the slip ratios; setting upper and lower limits for the sum mode target slip ratio and the difference mode target slip ratio, respectively, to limit the sum mode target slip ratio and the difference mode target slip ratio; and controlling the driving forces of the left drive system and the right drive system based on the sum mode target slip ratio and the difference mode target slip ratio after limitation, the sum model, and the difference model. A vehicle control method comprising: