Vehicle control device and vehicle control method

Abstract

A vehicle control device (10) according to the present disclosure controls the outputs of the left driving source and the right driving source of a vehicle, and comprises a calculation unit (21), a storage unit (22), and a control unit (23). The calculation unit (21) calculates a sum-corresponding value corresponding to the sum of the left target speed and the right target speed and a difference-corresponding value corresponding to the difference therebetween. The storage unit (22) stores: a sum model which is obtained by modeling the motion states of a left drive system, a right drive system, the left driving source, and the right driving source when the vehicle is traveling straight ahead, said sum model being such that a sum indication torque is derived by applying the sum-corresponding value thereto; and a difference model which is obtained by modeling the motion states of the left drive system, the right drive system, the left driving source, and the right driving source when the vehicle turns, said difference model being such that a difference indication torque is derived by applying the difference-corresponding value thereto. The control unit (23) controls the torque of the left driving source and the right driving source by using the sum indication torque and the difference indication torque.

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device and a vehicle control method for controlling a drive source mounted on a vehicle. [Background technology]

[0002] Conventionally, in a vehicle equipped with multiple drive sources, a method has been known in which a vehicle model that models the behavior of the drive force transmission system is used to control the operating state of each drive source while suppressing vibration in the drive force transmission system (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-103249 Summary of the Invention [Problem to be solved by the invention]

[0004] The behavior of the drivetrain is different when the vehicle is traveling straight and when it is turning. Therefore, it is necessary to develop separate controls for the vehicle traveling straight and turning. However, developing separate controls for the left and right drivetrains poses the problem that the control configuration tends to become complicated. Furthermore, the vehicle's driving state can be a complex state that combines both straight and turning states, which makes it difficult to improve controllability.

[0005] One of the objects of the present invention has been devised in light of the above-mentioned problems, and is to provide a vehicle control device and a vehicle control method that can improve controllability with a simple configuration. However, in addition to this object, another object of the present invention is to achieve effects derived from the respective configurations shown in the "Mode for Carrying Out the Invention" described below, which are effects that cannot be obtained with conventional technologies. [Means for solving the problem]

[0006] The disclosed vehicle control device and vehicle control method can be realized as the aspects or specific examples disclosed below, and solve at least some of the above problems. The disclosed vehicle control device is a vehicle control device for controlling outputs of a left drive source and a right drive source in a vehicle equipped with a left 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, and the vehicle control device includes a calculation unit that calculates a sum equivalent value that corresponds to the sum of a left target speed that is a target speed of the left drive source or the left drive source and a right target speed that is a target speed of the right drive source or the right drive source, and calculates a difference equivalent value that corresponds to the difference between the left target speed and the right target speed; a sum model that models the state of the vehicle and applies the sum equivalent value to derive a sum command torque for making the actual speeds of the left drive system and the right drive system or the left drive source and the right drive source follow their respective target speeds; a difference model that models the motion states of the left drive system and the right drive system, and the left drive source and the right drive source when the vehicle is turning and applies the difference equivalent value to derive a difference command torque for making the actual speeds of the left drive system and the right drive source follow their respective target speeds; and a control unit that uses the sum command torque and the difference command torque to control the torque of the left drive source and the right drive source.

[0007] The disclosed vehicle control method is a vehicle control method for controlling the outputs of a left drive source and a right drive source 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, the method comprising: preparing a sum model that models the motion states of the left drive system and the right drive system, and the left drive source and the right drive source when the vehicle is traveling straight; and preparing a difference model that models the motion states of the left drive system and the right drive system, and the left drive source and the right drive source when the vehicle is turning; and calculating a left target speed that is a target speed of the left drive system or the left drive source and a difference model that models the motion states of the right drive system or the right drive source. calculates a sum equivalent value that is the sum of the left target speed and the right target speed, which is the target speed of the right drive source, and calculates a difference equivalent value that is the difference between the left target speed and the right target speed, and by applying the sum equivalent value to the sum model, a sum command torque is obtained for making the actual speeds of the left drive system and the right drive system or the left drive source and the right drive source follow their respective target speeds when the vehicle is traveling straight, and by applying the difference equivalent value to the difference model, a difference command torque is obtained for making the actual speeds of the left drive system and the right drive source follow their respective target speeds when the vehicle is turning, and the torque of the left drive source and the right drive source is controlled using the sum command torque and the difference command torque. [Effects of the Invention]

[0008] According to the disclosed vehicle control device and vehicle control method, by separating a sum model corresponding to the vehicle traveling straight and a difference model corresponding to the vehicle traveling turning, and applying a sum equivalent value and a difference equivalent value to each model to derive a sum command torque and a difference command torque, it is possible to calculate a command torque that achieves a target speed with a simple configuration. Therefore, in a drivetrain that has different characteristics when traveling straight and when turning, it is possible to control while accurately grasping the state (behavior) of the drivetrain, and it is possible to improve controllability with a simple configuration, and it is possible to control the drivetrain to respond to any driving condition. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing the configuration of a vehicle control device and a vehicle; [Figure 2] 1 is a schematic diagram showing an example of the structure of a vehicle drive system. [Figure 3] FIG. 3 is a velocity diagram of a power distribution mechanism of a vehicle having the structure shown in FIG. 2. [Figure 4] FIG. 2 is a block diagram showing the flow of a vehicle control method. [Figure 5] FIG. 5 is a block diagram showing an example of the conversion process of FIG. 4. [Figure 6] FIG. 5 is a block diagram showing an example of the inverse transformation and control process of FIG. 4. [Figure 7] 1 is a schematic diagram illustrating the structure of a left drive train and a right drive train of a vehicle. FIG. [Figure 8] (A) is a schematic diagram of the sum model, and (B) is a schematic diagram of the difference model. [Figure 9] FIG. 1 is a schematic diagram for considering the behavior of a vehicle when traveling straight. [Figure 10] FIG. 2 is a schematic diagram showing the relationship between torque and speed when the vehicle is traveling straight. [Figure 11] FIG. 2 is a schematic diagram showing the relationship between torque and speed when the vehicle is turning. DETAILED DESCRIPTION OF THE INVENTION

[0010] The types of vehicles in which the disclosed vehicle control device and vehicle control method can be used include, for example, engine vehicles (gasoline vehicles, diesel vehicles), electric vehicles, and hybrid vehicles, which run by driving left and right wheels (left and right drive wheels) using at least one drive source (internal combustion engine or motor), and preferably run 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. Also, 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 equipped with a left drive system including a left axle and left wheels to which power is transmitted from the left drive source, and a right drive system including a right axle and right wheels to which power is transmitted from the right drive source.

[0011] The layout of each of the left and right drive sources may or may not be set to 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. [Example]

[0012] [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 (the left wheel) located on the left side of the vehicle 1, and 5R indicates the other (the right wheel) located on the right side. The positions of the left and right wheels 5 in the longitudinal direction do not matter, and they may be the front or rear wheels of the vehicle 1.

[0013] 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 that are separately provided from each other.

[0014] 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, left axle) connected to the left wheel 5L and an axle 4 (right axle 4R, right axle) connected to the right wheel 5R. The yaw control function actively controls the distribution ratio of the driving force (driving torque) 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 includes 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.

[0015] As shown in FIG. 2, the power distribution mechanism 3 includes a pair of speed reduction mechanisms (gear trains surrounded by dashed lines in FIG. 2) and a transmission mechanism (gear trains surrounded by dashed lines in FIG. 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.

[0016] 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 a planetary gear provided on each carrier and its rotation shaft are connected to each other. Each carrier supports the planetary gear so that it can rotate and also supports the planetary gear so that it revolves around the 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.

[0017] In addition, J in Fig. 2 M is 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 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 reduction 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 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 reduction 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).

[0018] Fig. 3 is a speed diagram of the power distribution mechanism 3. b1 and b2 shown in Figs. 2 and 3 represent torque difference amplification factors (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 power transmission from the left motor 2L to the right wheel 5R is b1, and the torque difference amplification factor related to power transmission from the left motor 2L to the left wheel 5L is b1+1. Furthermore, the torque difference amplification factor related to power transmission from the right motor 2R to the left wheel 5L is b2, and the torque difference amplification factor related to power transmission from the right motor 2R to the right wheel 5R is b2+1.

[0019] 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) of a DC circuit on the battery 7 side and power (AC power) of 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 a 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.

[0020] 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 from a left motor 2L (left drive source) is transmitted, and a right drivetrain including a right axle 4R and a right wheel 5R to which power from a right motor 2R (right drive source) is transmitted. The vehicle control device 10 has a function of controlling the output of each of the left motor 2L and the right motor 2R.

[0021] 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 each other 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.

[0022] 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).

[0023] 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.

[0024] [2. Vehicle control device] FIG. 4 is a schematic block diagram showing the flow of control (output control for the motor 2, using the vehicle control method according to the embodiment) performed by the vehicle control device 10. A sum model (sum-mode wheel speed FF model) and a difference model (difference-mode wheel speed FF model) are stored in advance in the storage device of the vehicle control device 10. That is, in this vehicle control method, the sum model and the difference model are first prepared. The sum model models the motion states of the left and right drive systems, and the left drive source (left motor 2L) and right drive source (right motor 2R) when the vehicle 1 travels straight, and the difference model models the motion states of the left and right drive systems, and the left drive source (left motor 2L) and right drive source (right motor 2R) when the vehicle 1 turns.

[0025] As shown in FIG. 4, the sum model applies a sum equivalent value to grasp the motion states of the left and right drive systems when the vehicle 1 travels straight, and the difference model applies a difference equivalent value to grasp the motion states of the left and right drive systems when the vehicle 1 turns. Specifically, the sum model applies (inputs) a sum equivalent value having an input element to derive a sum equivalent value (a sum equivalent value having an output element, hereinafter referred to as a "sum model state quantity") that represents the motion states of the left and right drive systems when the vehicle 1 travels straight. Similarly, the difference model applies (inputs) a difference equivalent value having an input element to derive a difference equivalent value (a difference equivalent value having an output element, hereinafter referred to as a "difference model state quantity") that represents the motion states of the left and right drive systems when the vehicle 1 turns.

[0026] The sum-equivalent value is a general term for a value equivalent to the sum of a left target speed representing the target speed of the left drive system or the left motor 2L among parameters including input parameters or output parameters of the left drive system (representing the behavior of the left drive system), and a right target speed representing the target speed of the right drive system or the right motor 2R among parameters including input parameters or output parameters of the right drive system (representing the behavior of the right drive system).The sum-equivalent value includes not only a simple sum, but also a value obtained by multiplying the sum by a predetermined coefficient, half the sum (arithmetic mean value), etc.Furthermore, the sum command torque refers to a torque equivalent to the sum of torques required to make the actual speeds of the left drive system and the right drive system (or the left motor 2L and the right motor 2R) follow their respective target speeds when the vehicle 1 is traveling straight.

[0027] The difference equivalent value is a general term for a value equivalent to the difference between a left target speed representing the target speed of the left drive system or the left motor 2L among parameters including input parameters or output parameters of the left drive system (representing the behavior of the left drive system), and a right target speed representing the target speed of the right drive system or the right motor 2R among parameters including input parameters or output parameters of the right drive system (representing the behavior of the right drive system).The difference equivalent value includes not only the simple difference, but also a value obtained by multiplying the difference by a predetermined coefficient, half the difference, etc.Furthermore, the difference command torque refers to a torque equivalent to the difference between the torques required to make the actual speeds of the left drive system and the right drive system (or the left motor 2L and the right motor 2R) follow their respective target speeds when the vehicle 1 is turning.

[0028] Hereinafter, the control that obtains the sum command torque based on the sum model will also be referred to as wheel speed control (sum). The wheel speed control (sum) of this embodiment is feedforward control (open-loop control). Also, the control that obtains the differential command torque based on the differential model will also be referred to as wheel speed control (difference). The wheel speed control (difference) of this embodiment is feedforward control (open-loop control).

[0029] Steps A1 and A2 in Fig. 4 correspond to a process (conversion process) of calculating a sum equivalent value and a difference equivalent value based on the left target speed and the right target speed. The values ​​of the left target speed and the right target speed are calculated by a known pre-stage control. In the pre-stage control, the left target speed and the right target speed are calculated based on the information detected by the various sensors 14 to 18, for example, so as to have magnitudes corresponding to the running state of the vehicle 1 and the driver's intention (intention to accelerate, decelerate, turn, etc.).

[0030] FIG. 5 is a block diagram showing a specific example of steps A1 and A2 (conversion process) in FIG. 4. LL (Or, left motor angular velocity ω LM ) is a specific example of the left target speed, and "right wheel target speed ω RL (or right motor angular velocity ω RM ) is a specific example of the right target speed. In step A1, half of the sum of the target speeds of the left and right wheels 5 is calculated, and the sum mode wheel angular speed ω SL(or sum mode motor angular velocity ω SM ) is output as the sum mode wheel angular velocity ω SL (or sum mode motor angular velocity ω SM ) corresponds to the sum equivalent value in FIG. 4. In step A2, half of the difference between the target speeds of the left and right wheels 5 is calculated, and the difference mode wheel angular velocity ω DL (or, the difference mode motor angular velocity ω DM ) is output as the differential mode wheel angular velocity ω DL (or, the difference mode motor angular velocity ω DM ) corresponds to the difference equivalent value in Figure 4.

[0031] Step A3 in Fig. 4 corresponds to a process in which a sum equivalent value is applied to the sum model to obtain a sum command torque (wheel speed control (sum), FF control). Step A4 in Fig. 4 corresponds to a process in which a difference equivalent value is applied to the difference model to obtain a difference command torque (wheel speed control (difference), FF control). Steps A5 and A6 in Figure 4 correspond to processes (inverse conversion and control processes) in which the left command torque and the right command torque are calculated using the sum command torque and the difference command torque, and the torques of the left motor 2L and the right motor 2R are controlled based on these left command torque and right command torque.

[0032] FIG. 6 is a block diagram showing a specific example of steps A5 and A6 (inverse conversion and control process) in FIG. 4. Sin " is a specific example of the sum torque, and "differential mode driving side torque T Din " is a specific example of the differential torque. In step A5, the sum mode driving side torque T Sin Difference mode drive side torque T Din Half of the value obtained by subtracting LM The output is the left motor input torque T LM corresponds to the left command torque in FIG. 4. In addition, in step A6, the sum mode driving side torque T Sin and differential mode drive torque T Din Half of the sum of these is calculated, and the right motor input torque TRM The right motor input torque T RM corresponds to the right indicated torque in Figure 4.

[0033] Next, a specific configuration for implementing the above control will be described. As shown in Fig. 1, a calculation unit 21, a storage unit 22, and a control unit 23 are provided inside the vehicle control device 10. 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 calculation unit 21 calculates a sum equivalent value and a difference equivalent value. The sum equivalent value and the difference equivalent value are calculated based on a left target speed and a corresponding right target speed. The left target speed includes, for example, a left motor angular speed ω LM , Left motor angular velocity (after deceleration) ω Lm , left drive side angular velocity ω Lds , left wheel angular velocity ω LL (left wheel target speed), etc. Similarly, the right target speed includes, for example, the right motor angular speed ω RM , Right motor angular velocity (after deceleration) ω Rm , right drive side angular velocity ω Rds , right wheel angular velocity ω RL (Right wheel target speed), etc.

[0035] The sum-equivalent value is, for example, the sum-mode motor angular velocity ω SM , Sum mode motor angular velocity (after deceleration) ω Sm , sum mode drive side angular velocity ω Sds , sum mode wheel angular velocity ω SL Similarly, the difference equivalent value includes, for example, the difference mode motor angular velocity ω DM ,Difference mode motor angular velocity (after deceleration) ω Dm , differential mode drive side angular velocity ω Dds , difference mode wheel angular velocity ω DL etc. are included.

[0036] Sum mode motor angular velocity ω SM and the difference mode motor angular velocity ω DM Each of the left motor angular velocity ω LM and right motor angular velocity ω RM The sum mode motor angular velocity (after deceleration) is calculated based on Sm and differential mode motor angular velocity (after deceleration) ω Dm Each of the left motor angular velocity (after deceleration) ω Lm and right motor angular velocity (after deceleration) ω Rm Below is an example of a calculation formula in which half the sum of the left target speed and the right target speed is used as the sum equivalent value, and half the difference between the left target speed and the right target speed is used as the difference equivalent value.

[0037]

number

[0038] The storage unit 22 stores a sum model that models the motion states of the left and right drive systems and the left drive source (left motor 2L) and right drive source (right motor 2R) when the vehicle 1 is traveling straight, and a difference model that models the motion states of the left and right drive systems and the left drive source (left motor 2L) and right drive source (right motor 2R) when the vehicle 1 is turning. Before describing the sum model and the difference model, a schematic structure of the left and right drive systems of the vehicle 1 will be described.

[0039] FIG. 7 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 J in Figure 7 is connected in parallel. LM is the inertia of the power distribution mechanism 3 side (drive side) for 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) for the right axle 4R, J Rwis the inertia of the right wheel 5R (load side) relative to the right axle 4R. Also, in Figure 7, the left driving side angular velocity ω Lds Derivative value of (left driving side angular acceleration), left wheel angular velocity ω LL The differential value (left wheel angular acceleration), right drive side angular velocity ω Rds Differential value (right drive side angular acceleration), right wheel angular velocity ω RL The differential value (right wheel angular acceleration) is also shown.

[0040] Based on the above schematic diagrams, the configuration of the sum model is modeled as shown in Fig. 8(A), and the configuration of the difference model is modeled as shown in Fig. 8(B). The sum model 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 running of the vehicle 1, and the difference model 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. Note that, although in this embodiment, the sum model and the difference model are both two-inertia system models, 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 Figure 8(A), the sum model uses the driving inertia J SM and stiffness K s and viscosity D s The spring damper is designed with the load side inertia (sum mode wheel nominal inertia) J SL The drive inertia J SM is the inertia J of the drive source (left motor 2L and right motor 2R). 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.

[0042]

number

[0043] As shown in Figure 8(B), the difference model uses the drive-side inertia J, which is the equivalent inertia when a difference between the left and right wheels occurs (when turning). DM and stiffness K s and viscosity D s The spring damper is designed with the load side inertia (differential mode wheel nominal inertia) J DL The drive inertia J DM is the inertia J of the drive source (left motor 2L and right motor 2R). M and the torque difference amplification factor (b1, b2, etc.) of the power distribution mechanism 3, DM =(2b1+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. Note that the drive-side inertia J DM and load inertia J DL Friction may also be taken into consideration when calculating the equation of motion for the differential model.

[0044]

number

[0045] By applying the sum equivalent value to the sum model, a sum command torque equivalent to the sum of the torques required to make the actual speeds of the left and right drive trains (or the left motor 2L and the right motor 2R) follow the target speeds when the vehicle 1 is traveling straight is obtained. For example, if the sum model is applied with the sum mode wheel angular velocity ω SL As a result of applying Sin is acquired as the sum command torque. The same applies to the difference model, and by applying a difference equivalent value to the above difference model, a difference command torque equivalent to the difference in torque required to make the actual speeds of the left drive system and the right drive system (or the left motor 2L and the right motor 2R) follow the target speed when the vehicle 1 is turning is acquired. For example, if the difference model is applied with the difference mode wheel angular velocity ω DL As a result of applying Dinis obtained as the differential torque indication.

[0046] The control unit 23 obtains a sum command torque and a difference command torque by applying the sum equivalent value and the difference equivalent value calculated by the calculation unit 21 to the sum model and the difference model stored in the storage unit 22, respectively, and controls the outputs of the left motor 2L and the right motor 2R using the sum command torque and the difference command torque. The control unit 23 controls the operating state of the inverter 6 so that the sum command torque and the difference command torque are obtained by driving the pair of motors 2 (i.e., so that both the sum command torque and the difference command torque can be achieved). This makes it easier to accurately control the motion states of the left drive system and the right drive system so that they are in the desired states.

[0047] Here, the sum mode wheel angular velocity ω calculated based on the target speeds of the left and right wheels 5 (target wheel speeds) SL and the difference mode wheel angular velocity ω DL As a result of applying the sum model and the difference model, the sum mode drive side torque T Sin and differential mode drive torque T Din The case where the sum mode driving torque T Sin and differential mode drive torque T Din The torque to be output by each of the pair of motors 2 is calculated based on the above equation, and the pair of inverters 6 are driven so as to obtain that torque.

[0048] Sum mode drive torque T Sin and differential mode drive torque T Din The calculation of the torque of each motor 2 based on the above can be realized by performing the inverse calculation of the sum equivalent value and the difference equivalent value. For example, the torque of each motor 2 to be calculated can be calculated as "left motor input torque T LM , right motor input torque T RM " and the torque when these torques are transmitted to axle 4 is defined as "left drive side torque T Lin , Right drive torque T Rin Next, let us consider the left drive torque T Lin and right drive torque T RinThe sum of these is the sum mode drive torque T Sin and the left drive torque T Lin and right drive torque T Rin The difference between the differential mode drive torque T Din The torque on the left drive side, T, is Lin and right drive torque T Rin Next, the left driving side torque T Lin and right drive torque T Rin Left motor input torque T corresponding to LM and right motor input torque T RM Calculate.

[0049] Then, the calculated left motor input torque T LM and right motor input torque T RM Each inverter 6 is driven so that the actual speed of the motor 2 and the left and right wheels 5 accurately tracks the target speed. This control improves wheel speed controllability. Furthermore, because the wheel speed tends to match the target speed even when a disturbance is input, the wheel speed is less likely to change suddenly even when the frictional resistance of the road surface or the driving force changes, and slippage is suppressed.

[0050] [3. Examples of sum model and difference model] [A. Load side transfer function (sum model)] FIG. 9 is a schematic diagram for deriving the load side inertia when the vehicle 1 is traveling straight. Here, the vehicle speed when the vehicle 1 is traveling straight is V x ,Wheel speed (forward speed of left and right wheels 5) is V SL , the vehicle weight is M, the wheel angular velocity (sum mode wheel speed) is ω SL , the driving force of the left and right wheels 5 is F Sx , the wheel radius is r. The sum mode wheel load torque T SL The sum mode axle torque T (torque corresponding to the reaction force from the road surface and the driving force) is the driving torque Sds If we linearize it assuming that it is determined by the following equation, the following equation holds:

[0051]

number

[0052] Based on the above equation, the transfer function of the sum mode load side (a relational expression including a transfer function that represents the input / output characteristics of a two-inertia system related to the sum model) can be obtained. Sn is the sum mode wheel nominal slip ratio (the wheel nominal slip ratio in the sum model).

number

[0053] FIG. 10 is a schematic diagram showing the relationship between torque and speed in the sum model. Here, the sum mode wheel load torque T SL , sum mode wheel angular velocity ω SL , sum mode axle torque T Sds , sum mode drive torque T Sin , sum mode drive side angular velocity ω Sds The relationship between J and M is the motor inertia, D M is the motor viscosity, J L is the inertia of the power distribution mechanism 3 (drive side) relative to the axle 4, D L is the load-side viscosity.

[0054] Sum mode drive side angular velocity ω Sds is the sum mode drive torque T Sin From sum mode axle torque T Sds The value obtained by subtracting "G -1 " and "1 / (J M ·s+D M )" and "G -1 " is calculated by multiplying Sum mode axle torque T Sds is the sum mode drive side angular velocity ω Sds From sum mode wheel angular velocity ω SL The value obtained by subtracting "(K s / s)+D s " is calculated by multiplying In addition, the sum mode wheel angular velocity ω SL is the sum mode axle torque T Sds Summation mode wheel load side torque TSL The value obtained by subtracting 1 / (J L ·s+D L ) is calculated.

[0055] [B. Load side transfer function (difference model)] The yaw rate of vehicle 1 when turning is γ, the tread is d, and the difference in left and right wheel speed is V. Dx Also, V x is the vehicle speed, V rlx is the left wheel reference wheel speed, V rrx is the reference wheel speed of the right wheel. Assuming the steering angle is zero, the yaw rate γ and the difference mode wheel angular velocity ω DL Considering the relationship between

[0056]

number

[0057] The equations of motion for the differential mode drive side, yaw motion, and lateral motion are formulated as follows: f is the steering angle, a y is the lateral acceleration, I is the yaw inertia of vehicle 1, C f is the front wheel cornering power, C r is rear wheel cornering power, f is the distance between the center of gravity and the front axle, l r is the distance between the center of gravity and the rear axle, β is the vehicle slip angle, F Dx is the difference between the left and right driving forces, λ D is the slip ratio in the difference model.

[0058]

number

[0059] Here, in order to model the transitional state of the vehicle 1 from a straight traveling state to a turning state, the steering angle δ f and lateral acceleration a yAssuming that is zero, the following transfer function on the differential mode load side (a relational expression including a transfer function that represents the input / output characteristics of a two-inertia system related to the differential model) is obtained:

number

[0060] FIG. 11 is a schematic diagram showing the relationship between torque and speed in the differential model. Here, the differential mode wheel load torque T DL , difference mode wheel angular velocity ω DL ,Differential mode axle torque T Dds , Differential mode drive torque T Din , differential mode drive side angular velocity ω Dds The relationship is shown. Differential mode drive side angular velocity ω Dds is the differential mode drive torque T Din Difference mode axle torque T Dds The value obtained by subtracting "1 / (1+b1+b2)" and "G -1 " and "1 / (J M ·s+D M )" and "G -1 It is calculated by multiplying " by "1 / (1+b1+b2)".

[0061] Differential mode axle torque T Dds is the differential mode driving side angular velocity ω Dds from the difference mode wheel angular velocity ω DL The value obtained by subtracting "(K s / s)+D s " is calculated by multiplying Difference mode wheel angular velocity ω DL is the differential mode axle torque T Dds Difference mode wheel load side torque T DL The value obtained by subtracting 1 / (J L ·s+D L ) is calculated.

[0062] [C. Driving side equation of motion (sum-difference model)] Regarding the derivation of the above sum model and difference model, the power distribution mechanism 3 may be expressed mathematically as follows using vector representation.

number

[0063] Using the above formula, the equations of motion (sum and difference) for the driving side are formulated for the left and right sides, as follows. Z in the formula 11 is the reduction ratio from the left drive source (left motor 2L) to the left axle (left axle 4L), Z 22 is the reduction ratio from the right drive source (right motor 2R) to the right axle (right axle 4R), Z c is the reduction ratio applied to the shafts on the opposite sides from the left and right drive sources.

[0064]

number

[0065] By applying a matrix to both sides of the above equation to convert to sum-difference mode, we obtain the following equation:

number

[0066] Here, if b1=b2=b, then Z 11 -Z c =Z 22 -Z c =|Z|,Z 11 +Z c =Z 22 +Z c = 1, the formula can be transformed as follows to obtain the equation of motion for motor 2 corresponding to the sum and difference modes. In this way, by decomposing the equation of motion on the drive side into each of the sum and difference modes, the two are decoupled.

[0067]

number

[0068] [D. Equations of motion for wheels and axles (sum and difference model)] Similar to the derivation of the equation of motion on the drive side, the equation of motion for the left and right wheels 5 (load side) and the axle 4 may be expressed mathematically as follows:

number

[0069] Here, the equation of motion of the left and right wheels 5 (load side) is substituted into the equation of motion of the axle 4, and J SM =G 2 J M ,D SM =G 2 D M ,J DM =G 2 (2b+1) 2 J M ,D DM =G 2 (2b+1) 2 D M By rearranging as above, the following transfer function is obtained:

number

[0070] In addition, the target wheel speed in the sum model and the difference model is ω SL-ref ,ω DL-ref Then, by properizing the inverse of the above transfer function with a second-order low-pass filter, the following equation can be obtained, which can calculate the axle input torque for the target speed. When the following equation is implemented in the format shown in Figure 4, K s =∞,D s =0,D SM =0,D SL =0,D DM =0,D DL =0.

[0071]

number

[0072] Here, by applying a sum equivalent value to the sum model, a sum command torque is derived for making the actual speed of the drive system and motor 2 follow the target speed. Also, by applying a difference equivalent value to the difference model, a difference command torque is derived for making the actual speed of the drive system and motor 2 follow the target speed. The control unit 23 controls the torque of motor 2 using these sum command torque and difference command torque.

[0073] In this way, by separating the sum model corresponding to when the vehicle 1 is traveling straight and the difference model corresponding to when it is turning, and applying the sum equivalent value and the difference equivalent value to each model to derive the sum command torque and the difference command torque, it is possible to find the command torque that realizes the target speed of the drive train and motor 2 with a simple configuration, and to control the outputs of the left and right motors 2 so that the command torque is obtained. Therefore, the actual speed of the drive train and motor 2 can be made to follow the target speed with high precision.

[0074] Furthermore, in a drivetrain that has different characteristics when traveling straight and when turning, the state (behavior) of the drivetrain can be accurately grasped and controlled, and controllability (for example, control accuracy and control response speed) can be improved with a simple configuration, enabling drive force control that can respond to any driving condition. Furthermore, the response characteristics of the vehicle 1 when traveling straight and when turning can be reflected in the outputs of the left and right motors 2, making it easy to achieve the desired motion state.

[0075] (2) In the above embodiment, both the sum model and the difference model can be constructed as a two-inertia system model. This simple configuration allows for accurate understanding of the motion states of the left and right drive trains when the vehicle 1 is traveling straight and when turning. Furthermore, it is possible to perform control that takes into account viscoelasticity for the different characteristics of traveling straight and turning. This improves the controllability of the vehicle 1.

[0076] (3) As shown in Figure 8(A), the above sum model can be expressed as a two-inertia system consisting of a drive-side inertia calculated based on the inertia of the left motor 2L and the right motor 2R, a spring damper designed in terms of stiffness and viscosity, and a load-side inertia calculated based on the body weight of the vehicle 1. Furthermore, the input / output characteristics of this two-inertia system can be expressed by transfer functions such as those shown in [Equation 5], [Equation 14], and [Equation 15]. This makes it possible to accurately grasp the behavior of the drive system when traveling straight ahead, taking viscoelasticity into account, and improve the controllability of the vehicle 1.

[0077] (4) As shown in Figure 8(B), the above difference model can be expressed as a two-inertia system consisting of a drive-side inertia, which is the equivalent inertia when a left-right difference occurs and is calculated based on the torque difference amplification factor, a spring damper designed based on stiffness and viscosity, and a load-side inertia calculated based on the yaw inertia of the vehicle 1. In addition, the input / output characteristics of this two-inertia system can be expressed by transfer functions such as those shown in [Equation 8], [Equation 14], and [Equation 15]. This makes it possible to accurately grasp the behavior of the drive system during cornering, taking viscoelasticity into account, and improve the controllability of the vehicle 1.

[0078] [5. Other] The above-described embodiment is merely illustrative, and does not intend to exclude various modifications or the use of techniques not explicitly described in the present embodiment. The components of the present embodiment can be modified in various ways without departing from the spirit of the present embodiment. Furthermore, the components of the present embodiment can be selected or combined as needed. For example, while the above-described embodiment illustrates a vehicle 1 equipped with a pair of motors 2 as a drive source, an internal combustion engine may be used instead of the motors 2, and the specific type of drive source is not important.

[0079] Furthermore, in the above embodiment, the vehicle 1 is illustrated as having a vehicle drive system (DM-AYC system) including a pair of motors 2 and a power distribution mechanism 3, but the concepts of the sum model and difference model can be used in any vehicle, and can also be used in vehicles that do not have a power distribution mechanism 3 or in-wheel motor vehicles, for example. As long as the vehicle has at least 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, it is possible to implement control similar to that of the above embodiment, and to obtain the same actions and effects as those of the above embodiment.

[0080] [6. Notes] The following notes are provided regarding the above-described embodiments and modifications. [Appendix 1] 1. A vehicle control method for controlling outputs of a left drive source and a right drive source in a vehicle having 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, the method comprising: a sum model that models the motion states of the left and right drive systems, and the left and right drive sources when the vehicle is traveling straight, and a difference model that models the motion states of the left and right drive systems, and the left and right drive sources when the vehicle is turning, calculating a sum equivalent value corresponding to the sum of a left target speed, which is a target speed of the left drive system or the left drive source, and a right target speed, which is a target speed of the right drive system or the right drive source, and calculating a difference equivalent value corresponding to the difference between the left target speed and the right target speed; applying the sum equivalent value to the sum model to obtain a sum command torque for causing the actual speeds of the left drive system and the right drive system or the left drive source and the right drive source to follow their respective target speeds when the vehicle is traveling straight; applying the difference equivalent value to the difference model to obtain a difference command torque for causing each of the actual speeds to follow each of the target speeds when the vehicle is turning; The torques of the left drive source and the right drive source are controlled using the sum command torque and the difference command torque. A vehicle control method comprising:

[0081] [Appendix 2] The sum model and the difference model are both two-inertia system models. 2. A vehicle control method according to claim 1,

[0082] [Appendix 3] The sum model includes a transfer function that represents input / output characteristics of a two-inertia system that includes a drive-side inertia calculated based on the inertias of the left drive source and the right drive source, a spring damper designed with stiffness and viscosity, and a load-side inertia calculated based on the vehicle body weight. 3. A vehicle control method according to claim 1 or 2.

[0083] [Appendix 4] The difference model includes a transfer function that represents the input / output characteristics of a two-inertia system that is composed of a drive-side inertia, which is an equivalent inertia when a torque difference occurs, calculated based on a torque difference amplification factor, a spring damper designed based on stiffness and viscosity, and a load-side inertia, which is calculated based on the yaw inertia of the vehicle. 4. A vehicle control method according to any one of claims 1 to 3. [Industrial Applicability]

[0084] The present invention is applicable to the vehicle control device manufacturing industry, and also to the vehicle manufacturing industry that mounts the vehicle control device. [Explanation of symbols]

[0085] 1 vehicle 2 Motor (drive source) 3 Power distribution mechanism 4 axles 5 Left and right wheels 6 inverters 7 Battery 10 Vehicle control device 14 Accelerator opening sensor 15 Brake sensor 16 Steering angle sensor 17 Resolver 18 Wheel speed sensor 21 Calculation section 22 Memory section 23 Control Unit

Claims

1. 1. A vehicle control device for controlling outputs of a left drive source and a right drive source 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, a calculation unit that calculates a sum equivalent value that corresponds to the sum of a left target speed that is a target speed of the left drive system or the left drive source and a right target speed that is a target speed of the right drive system or the right drive source, and calculates a difference equivalent value that corresponds to the difference between the left target speed and the right target speed; a sum model that models the motion states of the left and right drive systems, and the left and right drive sources when the vehicle is traveling straight, and that derives a sum command torque by applying the sum equivalent value to cause the actual speeds of the left and right drive systems or the left and right drive sources to follow their respective target speeds; a difference model that models the motion states of the left and right drive systems, and the left and right drive sources when the vehicle is turning, and that derives a difference command torque for causing each actual speed to follow each target speed by applying the difference equivalent value; and a control unit that controls the torques of the left drive source and the right drive source using the sum command torque and the difference command torque; A vehicle control device comprising:

2. The sum model and the difference model are both two-inertia system models.

2. The vehicle control device according to claim 1.

3. The sum model includes a transfer function that represents input / output characteristics of a two-inertia system that includes a drive-side inertia calculated based on the inertias of the left drive source and the right drive source, a spring damper designed with stiffness and viscosity, and a load-side inertia calculated based on the vehicle body weight.

3. The vehicle control device according to claim 1 or 2.

4. The difference model includes a transfer function that represents the input / output characteristics of a two-inertia system that is composed of a drive-side inertia, which is an equivalent inertia when a torque difference occurs between the left and right sides and is calculated based on a torque difference amplification factor, a spring damper designed with rigidity and viscosity, and a load-side inertia, which is calculated based on the yaw inertia of the vehicle.

3. The vehicle control device according to claim 1 or 2.

5. The difference model includes a transfer function that represents the input / output characteristics of a two-inertia system that is composed of a drive-side inertia, which is an equivalent inertia when a torque difference occurs between the left and right sides and is calculated based on a torque difference amplification factor, a spring damper designed with rigidity and viscosity, and a load-side inertia, which is calculated based on the yaw inertia of the vehicle.

4. The vehicle control device according to claim 3.

6. 1. A vehicle control method for controlling outputs of a left drive source and a right drive source in a vehicle having 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, the method comprising: a sum model that models the motion states of the left and right drive systems, and the left and right drive sources when the vehicle is traveling straight, and a difference model that models the motion states of the left and right drive systems, and the left and right drive sources when the vehicle is turning; calculating a sum equivalent value corresponding to the sum of a left target speed, which is a target speed of the left drive system or the left drive source, and a right target speed, which is a target speed of the right drive system or the right drive source, and calculating a difference equivalent value corresponding to the difference between the left target speed and the right target speed; applying the sum equivalent value to the sum model to obtain a sum command torque for causing the actual speeds of the left drive system and the right drive system or the left drive source and the right drive source to follow their respective target speeds when the vehicle is traveling straight; applying the difference equivalent value to the difference model to obtain a difference command torque for causing each of the actual speeds to follow each of the target speeds when the vehicle is turning; The torques of the left drive source and the right drive source are controlled using the sum command torque and the difference command torque. A vehicle control method comprising:

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