Control device and program

Abstract

An EVC (10) is provided with: a coefficient estimation unit (105) that estimates the maximum coefficient of friction of a road surface when a drive wheel travels on the road surface by rotating the drive wheel with respect to a moving body; a limit calculation unit (102) that calculates an upper torque limit for driving the drive wheels on the basis of the estimated maximum friction coefficient; and a target setting unit (103) that sets a target torque for driving the drive wheels so as not to exceed the torque upper limit.

Description

Priority Application

[0001] This application is based on Japanese Patent Application No. 2023-044631 filed on March 20, 2023, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present disclosure relates to a control device and program for a mobile body. BACKGROUND As a control device for a mobile body, i.e., a vehicle, there is known a slip control device described in Patent Literature 1. In the slip control device described in Patent Literature 1, in a case where it is determined that a drive wheel has slipped, a road surface friction coefficient μ is simply estimated from a drive torque and a drive wheel acceleration. PRIOR ART DOCUMENTS PATENT LITERATURE

[0004] Patent Literature 1: Japanese Patent Application Laid-Open No. H2-19622 SUMMARY In the estimation method of the road surface friction coefficient μ in the related art, the road surface friction coefficient μ is estimated at the time when large slip occurs, and thus, in the case of small slip, the road surface friction coefficient μ cannot be estimated, and the estimation frequency of the road surface friction coefficient μ becomes extremely low.

[0006] In particular, the relationship between the road surface friction coefficient μ and the slip rate s differs depending on the road surface condition, and if the maximum value of the road surface friction coefficient μ, i.e., the maximum friction coefficient μp, can be estimated, the drive control can be performed in such a manner that the slip rate s becomes corresponding to μp, and the optimum acceleration and stability corresponding to the road surface friction coefficient μ can be achieved.

[0007] The present disclosure provides a control device and program capable of performing drive wheel control using the maximum friction coefficient μp.

[0008] The present disclosure is a control device including: a coefficient estimation section that estimates a maximum friction coefficient of a road surface on which a drive wheel rotates to travel when the drive wheel is rotated by a mobile body; a limit calculation section that calculates a torque upper limit for driving the drive wheel in accordance with the estimated maximum friction coefficient; and a target setting section that sets a target torque for driving the drive wheel in such a manner that the target torque does not exceed the torque upper limit. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a structural view for explaining the structure of a vehicle on which an EVC of the present embodiment is mounted. Figure 2is a block diagram for explaining the functional configuration of the EVC of the present embodiment. Figure 3 is a flowchart for explaining the action of the EVC illustrated in Figure 2 Figure 4 is a flowchart for explaining the action of the EVC illustrated in Figure 2 Figure 5 is a flowchart for explaining the action of the EVC illustrated in Figure 2 Figure 6 is a flowchart for explaining the action of the EVC illustrated in Figure 2 Figure 7 is a flowchart for explaining the action of the EVC illustrated in Figure 2 Figure 8 is a flowchart for explaining the action of the EVC illustrated in Figure 2 Figure 9 is an example of a TsMAX-μp characteristic diagram referred to in explaining the action of the EVC illustrated in Figure 2 Figure 10 is an example of a Tfil-μp characteristic diagram referred to in explaining the action of the EVC illustrated in Figure 2 Figure 11 is a flowchart for explaining the action of the EVC illustrated in Figure 2 Figure 12 is a flowchart for explaining the action of the EVC illustrated in Figure 2 Figure 13 is a flowchart for explaining the action of the EVC illustrated in Figure 2 Figure 14 is an example of a μ-s characteristic diagram referred to in explaining the action of the EVC illustrated in Figure 2 is an example of a μ-ofst characteristic diagram referred to in explaining the action of the EVC illustrated in Figure 15 Figure 2 is a timing chart referred to in explaining the action of the EVC illustrated in Figure 16 is a timing chart referred to in explaining the action of the EVC illustrated in Figure 2 Figure 17 is a flowchart for explaining the action of the EVC illustrated in Figure 2 DETAILED DESCRIPTION

[0010] ​​​​​​​​​​​​​​Hereinafter, the present embodiment will be described with reference to the drawings. For the sake of facilitating the understanding of the description, the same reference signs are attached to the same constituent elements in each drawing as much as possible, and repetitive description is omitted.

[0011] As shown in FIG. 1, the vehicle 2 includes an EVC (Electric Vehicle Controller) 10, an EPS (Electric Power Steering) 20, a brake ECU (Electric Control Unit) 22, an inverter 24, a motor generator 26, a steering wheel 30, an accelerator pedal 32, a brake pedal 34, an EPS actuator 40, a differential gear 42, a right front wheel brake 44FR, a left front wheel brake 44FL, a right rear wheel brake 44RR, a left rear wheel brake 44RL, a right front wheel 46FR, a left front wheel 46FL, a right rear wheel 46RR, and a left rear wheel 46RL. Figure 1 The right front wheel 46FR and the left front wheel 46FL are steering wheels that determine the traveling direction of the vehicle 2. The right front wheel 46FR and the left front wheel 46FL are driven wheels that do not transmit driving force. The right front wheel 46FR is provided at the right front of the vehicle 2. The left front wheel 46FL is provided at the left front of the vehicle 2. The "front" refers to the advancing direction of the vehicle 2, and is the upward direction of the vehicle 2. Figure 2

[0013] The right front wheel brake 44FR is provided to the right front wheel 46FR. The right front wheel brake 44FR operates based on a brake signal output from the brake ECU 22, and applies a braking force to the right front wheel 46FR. The left front wheel brake 44FL is provided to the left front wheel 46FL. The left front wheel brake 44FL operates based on a brake signal output from the brake ECU 22, and applies a braking force to the left front wheel 46FL.

[0014] ​​The right front wheel 46FR and the left front wheel 46FL are configured to change the angle to the right and left in synchronization. The right front wheel 46FR and the left front wheel 46FL are steered by the EPS actuator 40. The EPS actuator 40 is configured to perform a steering operation based on a steering signal output from the EPS 20. A steering angle signal is input to the EPS 20. The steering angle signal is a signal output by operating the steering wheel 30. The steering angle signal is a signal that specifies a steering angle desired by the driver. A control signal is output from the EVC 10 to the EPS 20. A brake signal is output from the brake ECU to the EPS 20. The EPS 20 calculates the steering signal by appropriately calculating the steering angle signal, the control signal, and the brake signal, and outputs to the EPS actuator 40. The EPS 20 outputs the steering signal to the EVC 10 and the brake ECU 22. The EPS 20 is a control device for outputting the steering signal to the EPS actuator 40. The EPS 20 is a computer having constituent elements such as an interface for transmitting and receiving signals, a memory for storing information, a CPU for performing operations, and the like.

[0015] The right rear wheel 46RR and the left rear wheel 46RL are drive wheels that drive the vehicle 2. The right rear wheel 46RR is provided at the right rear of the vehicle 2. The left rear wheel 46RL is provided at the left rear of the vehicle 2. The "rear" is the direction in which the vehicle 2 moves backward, and is the downward direction of the vehicle 2. Figure 2

[0016] The right rear wheel brake 44RR is provided to the right rear wheel 46RR. The right rear wheel brake 44RR operates based on a brake signal output from the brake ECU 22, and applies a brake force to the right rear wheel 46RR. The left rear wheel brake 44RL is provided to the left rear wheel 46RL. The left rear wheel brake 44RL operates based on a brake signal output from the brake ECU 22, and applies a brake force to the left rear wheel 46RL.

[0017] The brake ECU 22 is a control device for outputting a brake signal to each brake to generate a desired brake force. The brake ECU 22 is a computer having constituent elements such as an interface for transmitting and receiving signals, a memory for storing information, a CPU for performing operations, and the like. A brake operation signal output by operating the brake pedal 34 is input to the brake ECU 22. A control signal is output from the EVC 10 to the brake ECU 22. A steering signal is output from the EPS 20 to the brake ECU 22. The brake ECU 22 calculates the brake signal by appropriately calculating the brake operation signal, the control signal, and the steering signal. The brake ECU 22 outputs the brake signal to the right front wheel brake 44FR, the left front wheel brake 44FL, the right rear wheel brake 44RR, and the left rear wheel brake 44RL. ​The motor generator 26 functions as an electric motor that generates driving force, and also functions as a generator that recovers regenerative energy. The motor generator 26 is rotationally driven by alternating current output from the inverter 24, and generates driving torque. The generated driving torque is transmitted to the right rear wheel 46RR and the left rear wheel 46RL in proportion via the differential gear 42.

[0019] The inverter 24 converts direct current supplied from a battery not shown into alternating current, and supplies it to the motor generator 26 at a desired frequency and voltage. The inverter 24 supplies electric power corresponding to the driving torque generated by the motor generator 26, based on a target torque signal output from the EVC 10.

[0020] The EVC 10 is a control device that comprehensively controls the vehicle 2. The EVC 10 is a computer having constituent elements such as an interface for transmitting and receiving signals, a memory for storing information, a CPU for executing arithmetic operations, and the like. A throttle operation signal corresponding to an operation of the throttle pedal 32 is input to the EVC 10. A steering signal is input from the EPS 20 to the EVC 10. A brake signal is input from the brake ECU 22 to the EVC 10. A motor current signal is input from the inverter 24 to the EVC 10. A shift position signal corresponding to an operation of a shift lever not shown is input to the EVC 10. The shift position signal includes, for example, a D signal indicating forward, and an R signal indicating reverse.

[0021] Next, the functional configuration of the EVC 10 as a control device will be described with reference to Figure 2 The EVC 10 is input with a drive wheel speed signal, a driven wheel speed signal, a G sensor signal, a motor current signal, a throttle operation signal, a brake operation signal, and a shift position signal. The drive wheel speed signal includes a signal indicating the rotational speed of the right rear wheel 46RR and a signal indicating the rotational speed of the left rear wheel 46RL. The driven wheel speed signal includes a signal indicating the rotational speed of the right front wheel 46FR and a signal indicating the rotational speed of the left front wheel 46FL. The G sensor signal is a signal output from a G sensor not shown, and is a signal indicating the acceleration applied to the vehicle 2. The motor current signal is a signal indicating the current value flowing through the motor generator 26.

[0022] As functional constituent elements, the EVC 10 includes a throttle control section 101, a limit calculation section 102, a target setting section 103, a slip control section 104, a coefficient estimation section 105, a ratio calculation section 106, and a coefficient estimation section 107.

[0023] The accelerator control section 101 is a section that calculates the accelerator request torque Ta based on various signals input to the EVC 10. The accelerator control section 101 calculates the accelerator request torque Ta that specifies the drive torque or the brake torque, for example, based on an accelerator operation signal or a brake operation signal. The accelerator control section 101 calculates the accelerator request torque Ta that specifies the forward or the reverse, for example, based on a shift position signal. The accelerator control section 101 outputs the calculated accelerator request torque Ta to the limit calculation section 102.

[0024] The limit calculation section 102 is a section that performs the upper limit processing of the torque on the accelerator request torque Ta that specifies the drive torque or the brake torque. The limit calculation section 102 calculates the slip limit torque TsMAX that is the upper limit of the torque for driving the drive wheels, in accordance with the maximum friction coefficient μp. The limit calculation section 102 outputs the calculated slip limit torque TsMAX to the target setting section 103.

[0025] The target setting section 103 is a section that sets the target torque for driving the above-described drive wheels in such a manner that the torque does not exceed the upper limit of the torque, that is, the slip limit torque TsMAX. The target setting section 103 compares the slip limit torque TsMAX and the slip torque Ts output from the slip control section 104 and sets the smaller one as the target torque.

[0026] The target setting section 103 applies the torque that acts in the drive direction or the brake direction, that is, the brake drive torque, to the right rear wheel 46RR and the left rear wheel 46RL that are the drive wheels of the vehicle 2 that is the moving body. The target setting section 103 outputs the target torque signal that specifies the brake drive torque to the inverter 24 and the brake ECU 22. The target setting section 103 sets the minimum torque among the slip limit torque TsMAX or the slip torque Ts as the target torque. The brake torque that acts in the brake direction can be applied not only to the drive wheels but also to the driven wheels. The brake torque that acts in the brake direction can also be applied as the regenerative brake torque of the motor generator 26. The brake torque that acts in the brake direction can also be applied as the friction brake torque of the right front wheel brake 44FR, the left front wheel brake 44FL, the right rear wheel brake 44RR, and the left rear wheel brake 44RL.

[0027] The slip control section 104 is a section that calculates the slip torque Ts. The calculation method of the slip torque Ts will be described later in detail.

[0028] The ratio calculation section 106 calculates the slip ratio s that indicates the slip state of the right rear wheel 46RR and the left rear wheel 46RL that are the drive wheels with respect to the road surface on which the vehicle 2 that is the moving body travels.

[0029] The coefficient calculation unit 107 uses information including braking drive torque and drive wheel speed to calculate the friction coefficient μ of the right rear wheel 46RR and left rear wheel 46RL relative to the road surface.

[0030] The coefficient estimation unit 105 filters the combined data of the slip ratio s calculated by the ratio calculation unit 106 and the friction coefficient μ calculated by the coefficient calculation unit 107 at the same time as the slip ratio into selected data or non-selected data. The coefficient estimation unit 105 uses multiple selected data to estimate the maximum value of the friction coefficient μ, i.e., the maximum friction coefficient μp.

[0031] Next, refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 This explains the method for estimating the maximum friction coefficient μp. Figure 3 In step S101, the throttle control unit 101 calculates the required throttle torque Ta. The throttle control unit 101 determines whether the calculated required throttle torque Ta is greater than 0. If the required throttle torque Ta > 0 (S101: Yes), it is determined that the unit is in an acceleration state, and the process proceeds to step S102. If the required throttle torque Ta is not greater than 0 (S101: No), it is determined that the unit is in a deceleration state, and the process proceeds to step S103.

[0032] In step S102, the limit calculation unit 102 sets the acceleration / deceleration determination flag XACC to "1". After the processing of step S102 is completed, the process proceeds to step S104. In step S103, the limit calculation unit 102 sets the acceleration / deceleration determination flag XACC to "0". After the processing of step S103 is completed, the process proceeds to step S105.

[0033] In step S104, the ratio calculation unit 106 compares the wheel speed Vrr of the right rear wheel 46RR and the wheel speed Vrl of the left rear wheel 46RL. The ratio calculation unit 106 determines which of the two wheels, the right rear wheel 46RR and the left rear wheel 46RL, is in a low μ state. Step S104 is a determination based on the acceleration state premise; therefore, the wheel with the larger speed is in a low μ state. If wheel speed Vrl > wheel speed Vrr (S104: Yes), the process proceeds to step S107. If wheel speed Vrl does not > wheel speed Vrr (S104: No), the process proceeds to step S106.

[0034] In step S106, the ratio calculation unit 106 calculates the slip ratio s using the following formula (f001). s = (Vrr - Vb) / Vb(f001) Vb is the vehicle body speed, which can be calculated by a well-known method. As the vehicle body speed Vb, the driven wheel speed V can also be used.

[0035] In step S107, the ratio calculating portion 106 calculates the slip ratio s by the following equation (f002). s = (Vrl - Vb) / Vb (f002) In step S105, the ratio calculating portion 106 compares the wheel speed Vrr of the right rear wheel 46RR with the wheel speed Vrl of the left rear wheel 46RL. The ratio calculating portion 106 judges which of the right rear wheel 46RR side and the left rear wheel 46RL side is in the low μ state. Step S103 is the judgment of the deceleration state prerequisite, and therefore, the side of which the wheel speed is smaller is in the low μ state. If the wheel speed Vrl > the wheel speed Vrr (S105: YES), the processing proceeds to step S109. If the wheel speed Vrl > the wheel speed Vrr (S105: NO), the processing proceeds to step S108.

[0037] In step S108, the ratio calculating portion 106 calculates the slip ratio s by the following equation (f002). s = (Vrl - Vb) / Vb (f002)

[0038] In step S109, the ratio calculating portion 106 calculates the slip ratio s by the following equation (f001). s = (Vrr - Vb) / Vb (f001)

[0039] After the processing of step S106, step S107, step S108, and step S109 ends and the slip ratio s is calculated, the processing proceeds to step S110.

[0040] In step S110, the coefficient calculating portion 107 calculates the friction coefficient μ. The friction coefficient μ is calculated by dividing the tire load Fz by the driving force Fx. The driving force Fx is calculated by the following equation (f003). [Mathematical Expression 1] M is the vehicle body weight. V is the driven wheel speed. Fr is the vehicle R / L (Road Load), and is the resistance received when traveling at a constant speed on a paved horizontal road. Fr is calculated by a map search corresponding to the vehicle body speed Vb. T MG is the driving torque generated by the motor generator 26. T MG It can be estimated from the motor current, and a low-pass filter having a time constant simulating the delay of the MG torque is applied for the operation. T MGThe torque is distributed to the left and right wheels in proportion by the differential gear 42. L is a load or loss associated with the motor generator 26. L It is calculated by a map search corresponding to the drive wheel speed Vd. r is the tire radius.

[0041] The tire load Fz is calculated by the following equation (f004). [Equation 2] lr is the distance from the center of gravity of the vehicle 2 to the center of the rear wheel. L is the wheel distance between the front and rear wheels. h is the center of gravity height of the vehicle 2. The friction coefficient μ is calculated by the following equation (f005). [Equation 3] J is the inertia around the drive wheel. ω is the drive wheel speed. The drive wheel acceleration can be used for the operation by applying a low-pass filter having a time constant of a noise elimination degree. In addition, the friction coefficient μ can also be found from the drive torque T MG and the drive wheel acceleration ΔVd.

[0042] In step S110, after the friction coefficient μ is calculated, the process proceeds to Figure 4 step S111 in FIG. 11. Referring to Figure 4 the description will be continued.

[0043] In step S111, the accelerator control section 101 calculates the accelerator required torque Ta. The accelerator control section 101 judges whether the calculated accelerator required torque Ta is greater than 0. If the accelerator required torque Ta > 0 (S111: YES), it is judged that the vehicle is in an acceleration state, and the process proceeds to step S112. If the accelerator required torque Ta is not greater than 0 (S111: NO), it is judged that the vehicle is in a deceleration state, and the process proceeds to step S113.

[0044] In step S112, the ratio calculation section 106 judges whether the slip rate change ratio Δs is 0 or more. If the slip rate change ratio Δs ≥ 0 (S112: YES), the process proceeds to step S114. If the slip rate change ratio Δs < 0 (S112: NO), the process proceeds to step S119. Since the change in the slip rate has hysteresis on the acceleration side and the deceleration side, the judgment is made considering the hysteresis in the judgment in step S112.

[0045] In step S113, the ratio calculation portion 106 determines whether the slip ratio change ratio As is 0 or less. If the slip ratio change ratio As < 0 (S113: YES), the process proceeds to step S119. If the slip ratio change ratio As > 0 (S113: NO), the process proceeds to step S114. Since the change in the slip ratio has hysteresis on the acceleration side and the deceleration side, the determination in step S113 is made taking the hysteresis into account.

[0046] In step S114, the ratio calculation portion 106 determines whether the absolute value of the slip ratio s is smaller than a prescribed value Mx. If | slip ratio s | < Mx (S114: YES), the process proceeds to step S115. If | slip ratio s | < Mx (S114: NO), the process proceeds to step S119.

[0047] In step S115, the coefficient calculation portion 107 determines whether the friction coefficient μ is in the vicinity of 0. If | μ | > Pd (S115: YES), the process proceeds to step S116. If | μ | > Pd (S115: NO), the process proceeds to step S119. The determination value Pd can be 0 or a value in the vicinity of 0.

[0048] In step S116, the accelerator control portion 101 determines whether the absolute value of the drive wheel speed Vd is greater than 1 kph. If | Vd | > 1 kph (S116: YES), the process proceeds to step S117. If | Vd | > 1 kph (S116: NO), the process proceeds to step S119. In addition, if the resolver rotation sensor of the motor generator can be used to accurately measure the drive wheel speed Vd, the process of step S116 can not be performed.

[0049] In step S117, it is determined whether the steering angle is in a steering state. If | steering angle | < Ps (step S117: YES), the process proceeds to step S118. If | steering angle | < Ps (step S117: NO), the process proceeds to step S119. The determination value Ps is set to a value for determining whether the steering angle is in a steering state or a straight-ahead state. In addition, if the lateral force correction is performed to estimate, the process of step S117 can not be performed.

[0050] In step S118, the coefficient estimation portion 105 sets the mask flag Xmask of the combination data (μ, s) of the friction coefficient μ and the slip ratio s to 0. In step S118, the coefficient estimation portion 105 sets the mask flag Xmask of the combination data (μ, s) of the friction coefficient μ and the slip ratio s to 1. After the mask flag setting in steps S118 and S119 is completed, the process proceeds to step S121 in Figure 5 In step S118, the coefficient estimation portion 105 sets the mask flag Xmask of the combination data (μ, s) of the friction coefficient μ and the slip ratio s to 0. In step S118, the coefficient estimation portion 105 sets the mask flag Xmask of the combination data (μ, s) of the friction coefficient μ and the slip ratio s to 1. After the mask flag setting in steps S118 and S119 is completed, the process proceeds to step S121 inFigure 5 The explanation will be continued.

[0051] In step S121, the coefficient estimation section 105 judges whether or not the mask flag Xmask of the combination data (μ, s) of the friction coefficient μ and the slip ratio s is 0. If Xmask = 0 (step S121: YES), the process proceeds to step S122. If Xmask ≠ 0 (step S121: NO), the process proceeds to step S124.

[0052] In step S122, the coefficient estimation section 105 stores the combination data (μ, s) of which the mask flag Xmask is 0. The combination data (μ, s) of which the mask flag Xmask is 0 becomes selected data to be stored. The combination data (μ, s) of which the mask flag Xmask is 1 becomes non-selected data to be not stored. In step S123 subsequent to step S122, the coefficient estimation section 105 increments the sample counter Cspι by one.

[0053] In step S124, the coefficient estimation section 105 judges whether or not the sample counter Cspι is 10 or more. If the sample counter Cspι ≥ 10 (step S124: YES), the process proceeds to step S125. If the sample counter Cspι < 10 (step S124: NO), the process proceeds to step S128.

[0054] In step S125, the coefficient estimation section 105 estimates the maximum value of the friction coefficient μ, i.e., the maximum friction coefficient μp, by cubic function approximation. The coefficient estimation section 105 adds (0, 0) as origin data to the combination data (μ, s) of which the prescribed number is stored, and estimates the maximum friction coefficient μp by cubic function approximation. In step S126 subsequent to step S125, the coefficient estimation section 105 resets the sample counter Cspι. In step S127 subsequent to step S126, the coefficient estimation section 105 eliminates the stored combination data (μ, s).

[0055] After the process of step S127 is completed, the process proceeds to step S128. Figure 6 The explanation will be continued. Figure 6 The explanation will be continued.

[0056] In step S128, the limit calculation section 102 judges whether or not the acceleration / deceleration determination flag XACC is 1. If the acceleration / deceleration determination flag XACC is 1 (step S128: YES), the process proceeds to step S129. If the acceleration / deceleration determination flag XACC is not 1 (step S128: NO), the process proceeds to step S130.

[0057] In step S129, the limit calculation portion 102 sets the last determination flag XMYUACC to "0". In step S130, the limit calculation portion 102 sets the last determination flag XMYUACC to "1". The processing ends after step S129 or step S130.

[0058] Next, the torque limitation corresponding to the maximum friction coefficient μp will be described with reference to Figure 7 、 Figure 8 . Figure 7 In step S201, the maximum friction coefficient μp is estimated. The estimation method of the maximum friction coefficient μp is as described with reference to Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 . The processing ends after step S201, and proceeds to step S202.

[0059] In step S202, the limit calculation portion 102 sets the slip limit torque TsMAX. As shown in Figure 9 , the slip limit torque TsMAX is determined by a correlation with the maximum friction coefficient μp. For example, the slip limit torque TsMAX_ice corresponds to the maximum friction coefficient μp_ice of the icy road. For example, the slip limit torque TsMAX_dry corresponds to the maximum friction coefficient μp_dry of the dry road. The correlation between μp and TsMAX as exemplified in Figure 11 is held in a map. The processing ends after step S202, and proceeds to step S203.

[0060] In step S203, the limit calculation portion 102 compares the slip limit torque TsMAX with the throttle request torque Ta. If Ta > TsMAX (step S404: YES), the processing proceeds to step S204. If Ta > TsMAX (step S404: NO), the processing proceeds to step S205.

[0061] In step S204, the limit calculation portion 102 limits the throttle request torque Ta within a range having the slip limit torque TsMAX as an upper limit. The processing ends after step S204, and proceeds to step S205.

[0062] In step S205, the limit calculation portion 102 hysteresis-corrects the maximum friction coefficient μp. The hysteresis correction of the maximum friction coefficient μp will be described later in detail. The processing ends after step S205, and proceeds to step S206 of Figure 8 .

[0063] In Figure 8In step S206, the slip control portion 104 determines whether or not the slip control flag Xslip is 1. If the slip control flag Xslip is 1 (step S206: YES), the process proceeds to step S207. If the slip control flag Xslip is not 1 (step S206: NO), the process proceeds to step S210.

[0064] In step S207, the slip control portion 104 determines whether or not the initial slip state is present. The slip control portion 104 determines whether or not the initial slip state is present on the basis of the difference between the drive wheel speed V* and the vehicle body speed Vb. The drive wheel speed V* indicates the drive wheel speed of the larger one of the left and right wheels. If |V* - Vb| ≥ 3 kph (step S207: YES), the process proceeds to step S208. If |V* - Vb| < 3 kph (step S207: NO), the process proceeds to step S209.

[0065] In step S208, the limit calculation portion 102 slightly corrects the slip limit torque TsMAX downward using the following expression (f101). TsMAX = TsMAX - ΔK (f101) In step S209, the limit calculation portion 102 slightly corrects the slip limit torque TsMAX upward using the following expression (f102). TsMAX = TsMAX + ΔK (f102) After the process of steps S208 and S209 ends, the process proceeds to step S210. In step S210, the limit calculation portion 102 sets the torque filter time constant Tfil. The torque filter time constant Tfil is set in accordance with the estimated maximum friction coefficient μp. As illustrated in the example, Figure 10 The relationship between the maximum friction coefficient μp and the torque filter time constant Tfil is determined in advance. For example, the torque filter time constant Tfil_ice corresponds to the maximum friction coefficient μp_ice of an icy road. For example, the torque filter time constant Tfil_dry corresponds to the maximum friction coefficient μp_dry of a dry road.

[0068] After the process of step S210 ends, the process proceeds to step S211. In step S211, the limit calculation portion 102 performs the torque filter correction corresponding to the road μ. The limit calculation portion 102 performs the first-order low-pass filter correction using the torque filter time constant Tfil.

[0069] After the processing in step S211 is completed, the process proceeds to step S212. In step S212, the limit calculation unit 102 determines whether the slip control prohibition flag XMYU is 1. If the slip control prohibition flag XMYU is 1 (step S212: Yes), the process proceeds to step S213. If the slip control prohibition flag XMYU is not 1 (step S212: No), the process returns to the previous step.

[0070] In step S123, the limit calculation unit 102 performs a correction prohibition process. Specifically, slip control corresponding to the maximum friction coefficient μp is prohibited.

[0071] Next, refer to Figure 11 , Figure 12 To illustrate slip control. Figure 11 In step S301, the throttle control unit 101 calculates the required throttle torque Ta. The throttle control unit 101 determines whether the calculated required throttle torque Ta is greater than 0. If the required throttle torque Ta > 0 (S301: Yes), it is determined that the unit is in an acceleration state, and the process proceeds to step S302. If the required throttle torque Ta is not greater than 0 (S301: No), it is determined that the unit is in a deceleration state, and the process proceeds to step S303.

[0072] In step S302, the slip control unit 104 compares the wheel speed Vrr of the right rear wheel 46RR with the wheel speed Vrl of the left rear wheel 46RL. The slip control unit 104 determines whether to select the right rear wheel 46RR or the left rear wheel 46RL as the drive wheel speed. Since step S302 is a determination based on the acceleration state, the wheel speed with the larger speed is selected as the drive wheel speed. If wheel speed Vrl > wheel speed Vrr (S302: Yes), the process proceeds to step S305. If wheel speed Vrl > wheel speed Vrr (S302: No), the process proceeds to step S304.

[0073] In step S304, the slip control unit 104 sets the wheel speed Vrr of the right rear wheel 46RR to the drive wheel speed Vd. In step S305, the slip control unit 104 sets the wheel speed Vrl of the left rear wheel 46RL to the drive wheel speed Vd.

[0074] In step S303, the slip control portion 104 compares the wheel speed Vrr of the right rear wheel 46RR with the wheel speed Vrl of the left rear wheel 46RL. The slip control portion 104 judges which of the right rear wheel 46RR side and the left rear wheel 46RL side should be selected as the drive wheel speed. Since step S303 is the judgment of the deceleration state premise, the side of the smaller wheel speed is selected as the drive wheel speed. If it is wheel speed Vrl > wheel speed Vrr (S303: YES), the processing proceeds to step S307. If it is not wheel speed Vrl > wheel speed Vrr (S303: NO), the processing proceeds to step S306.

[0075] In step S307, the slip control portion 104 sets the wheel speed Vrr of the right rear wheel 46RR as the drive wheel speed Vd. In step S306, the slip control portion 104 sets the wheel speed Vrl of the left rear wheel 46RL as the drive wheel speed Vd.

[0076] After the processing of step S304, step S305, step S306, and step S307 ends and the drive wheel speed Vd is calculated, the processing proceeds to step S308.

[0077] In step S308, the slip control portion 104 judges whether or not to start the slip control. In the case where the absolute value of the difference between the drive wheel speed Vd and the vehicle body speed Vb is 3 kph or more, the slip control portion 104 judges to start the slip control. If it is |Vd - Vb| ≥ 3 kph (S308: YES), the processing proceeds to step S309. If it is not |Vd - Vb| ≥ 3 kph (S308: NO), the processing proceeds to step S310.

[0078] In addition, the vehicle body speed Vb is calculated from the wheel speed of the right front wheel 46FR and the wheel speed of the left front wheel 46FL in the two-wheel drive case illustrated below. Thus, the driven wheel speed is calculated from the wheel speed of the right front wheel 46FR and the wheel speed of the left front wheel 46FL, and is used as the vehicle body speed Vb. Figure 1 In step S309, the slip control portion 104 sets the slip control flag Xslip to 1, and the processing proceeds to step S311 of FIG. 6.

[0079] Figure 12 In step S310, the slip control portion 104 judges whether or not the slip control flag Xslip is 1. If the slip control flag Xslip is 1 (S310: YES), the processing proceeds to step S311 of FIG. 6. If the slip control flag Xslip is not 1 (S310: NO), the processing proceeds to step S316 of FIG. 6.

[0080] In step S310, the slip control portion 104 judges whether or not the slip control flag Xslip is 1. If the slip control flag Xslip is 1 (S310: YES), the processing proceeds to step S311 of FIG. 6. If the slip control flag Xslip is not 1 (S310: NO), the processing proceeds to step S316 of FIG. 6. Figure 12 Figure 12 In step S310, the slip control portion 104 judges whether or not the slip control flag Xslip is 1. If the slip control flag Xslip is 1 (S310: YES), the processing proceeds to step S311 of FIG. 6. If the slip control flag Xslip is not 1 (S310: NO), the processing proceeds to step S316 of FIG. 6.

[0081] ​​In Figure 12 In step S211, the slip control portion 104 determines whether or not the accelerator request torque Ta is greater than 0. If the accelerator request torque Ta is greater than 0 (S311: YES), it is determined that the vehicle is in an accelerating state, and the process proceeds to step S312. If the accelerator request torque Ta is not greater than 0 (S311: NO), it is determined that the vehicle is in a decelerating state, and the process proceeds to step S313.

[0082] In step S212, the slip control portion 104 calculates the target slip speed Vcmd by the following expression (f201). Vcmd = (1 + a) x Vb (f201) Vb is the vehicle body speed. A is a value calculated in accordance with the slip ratio corresponding to the maximum friction coefficient μρ. The μ-s characteristic curve is different in an icy road and a packed snow road. In the present embodiment, since the maximum friction coefficient μρ has been presumed, the slip ratio s corresponding to the presumed maximum friction coefficient μρ can be determined. The value a is a value corresponding to the determined slip ratio s, and is, for example, 0.03 if the slip ratio s is 3%.

[0083] In step S313, the slip control portion 104 calculates the target slip speed Vcmd by the following expression (f202). Vcmd = (1 - a) x Vb (f202) Vb is the vehicle body speed. A is a value calculated in accordance with the slip ratio corresponding to the maximum friction coefficient μρ. Since a has been described in expression (f201), the description thereof is omitted.

[0084] In steps S312 and S313, after the target slip speed Vcmd is calculated, the process proceeds to step S314. In step S314, the slip control portion 104 determines whether or not the slip control flag Xslip is 1. If the slip control flag Xslip is 1 (S314: YES), the process proceeds to step S315. If the slip control flag Xslip is not 1 (S314: NO), the process ends and returns.

[0085] In step S315, the slip control portion 104 sets the slip torque Ts. The slip control portion 104 performs PI_FB control such that the drive wheel speed Vd becomes the target slip speed Vcmd, and sets the slip torque Ts.

[0086] The slip control portion 104 calculates the speed deviation e using the following expression (f203). e = Vcmd - Vd (f203) The slip control portion 104 calculates the slip torque Ts using the following expression (f204). Ts=Kp×e+Ki×∫e(f204) In equation (f204), Kp is the preset proportional gain. In equation (f204), Ki is the preset integral gain. The slip control unit 104 uses the following formula (f205) to limit the slip torque Ts within the range from the lower limit Tmin to the upper limit Tmax. The lower limit Tmin and the upper limit Tmax are preset. Tmin < Ts < Tmax(f205) After the processing in step S315 is completed, the process proceeds to step S316. In step S316, the slip control unit 104 compares the slip torque Ts with the throttle required torque Ta, and determines whether slip control has ended. If Ts > Ta (S316: Yes), it is determined that slip control has ended, and the process proceeds to step S318. If Ts > Ta (S316: No), the process proceeds to step S317.

[0088] In step S317, the slip control unit 104 determines whether the slip state has been released. If it is |V * If -Vb|≤0 (S317: Yes), then the slip state is considered to be released, and the process proceeds to step S318. If it is not |V * If -Vb|≤0 (S317: No), then the processing ends and returns.

[0089] In step S317, the slide control unit 104 updates the slide control flag Xslip to 0. Next, refer to Figure 13 The hysteresis corrections for the maximum friction coefficient μp and the slip limit torque TsMAX are explained. Figure 13 In step S401, the limit calculation unit 102 determines whether the acceleration / deceleration determination flag XACC is 1. If the acceleration / deceleration determination flag XACC is 1, it is determined that the device is accelerating (step S401: Yes), and the process proceeds to step S402. If the acceleration / deceleration determination flag XACC is not 1, it is determined that the device is decelerating (step S401: No), and the process returns.

[0091] In step S402, the limit calculation unit 102 determines whether the previous determination flag XMYUACC is 1. If the previous determination flag XMYUACC is 1, it is determined that there was a previous acceleration (step S402: Yes), and the process proceeds to step S403. If the acceleration / deceleration determination flag XACC is not 1, it is determined that there was a previous acceleration (step S402: No), and the process returns.

[0092] In step S403, the limit calculation portion 102 performs hysteresis correction on the slip limit torque TsMAX. As shown in FIG. 6, the μ-s characteristic curve is different at the time of acceleration and at the time of deceleration. In the present embodiment, since the maximum friction coefficient μρ has been estimated, the slip ratio s corresponding to the estimated maximum friction coefficient μρ can be determined. The maximum friction coefficient μρ2 at the time of acceleration is larger than the maximum friction coefficient μρ1 at the time of deceleration with respect to the same slip ratio s. Figure 14

[0093] As shown in FIG. 6, since the slip limit torque TsMAX is determined by the correlation with the maximum friction coefficient μρ, the slip limit torque TsMAX at the time of acceleration is larger than the slip limit torque TsMAX at the time of deceleration. Figure 9

[0094] As shown in FIG. 6, the offset amount ofst is determined by the correlation with the road surface μ. The offset amount ofst is an amount of correction on the slip limit torque TsMAX at the time of deceleration and the slip limit torque TsMAX at the time of acceleration. The offset amount ofst can also be changed to the "μ large" curve in FIG. 6, for example, depending on the gradient, the drive mode, the weight, and the like. Figure 15 Figure 15 The coefficient estimation portion 105 estimates the offset amount ofst.

[0095] The limit calculation portion 102 performs hysteresis correction on the slip limit torque TsMAX using the following equation (f301). TsMAX = TsMAX + ofst (f301) After the process in step S403 ends, the process proceeds to step S404. In step S404, the limit calculation portion 102 sets the last determination flag XMYUACC to "0". The process ends after step S404.

[0097] Figure 16 The relationship between the vehicle speed and the maximum friction coefficient is shown in a time chart. As shown in FIG. 7, the limit calculation portion 102 estimates the maximum friction coefficient μρ while decelerating from time t1 to stopping. The acceleration / deceleration determination flag XACC is "0", and the last determination flag XMYUACC is "1". Since the μρ estimation at the time of acceleration cannot be completed in time at time t2 at the start, the maximum friction coefficient μρ and the slip limit torque TsMAX subjected to hysteresis correction processing are used. Since the estimation of μρ at the time of acceleration is completed at time t3, the estimated maximum friction coefficient μρ and the slip limit torque TsMAX are used. Figure 16 Next, the relationship between the vehicle speed and the maximum friction coefficient is shown in a time chart. As shown in FIG. 8, the limit calculation portion 102 estimates the maximum friction coefficient μρ while decelerating from time t1 to stopping. The acceleration / deceleration determination flag XACC is "0", and the last determination flag XMYUACC is "1". Since the μρ estimation at the time of acceleration cannot be completed in time at time t2 at the start, the maximum friction coefficient μρ and the slip limit torque TsMAX subjected to hysteresis correction processing are used. Since the estimation of μρ at the time of acceleration is completed at time t3, the estimated maximum friction coefficient μρ and the slip limit torque TsMAX are used.

[0098] Figure 17 ​​​​The slip control prohibition corresponding to the road surface gradient will be described. In step S501, the target setting portion 103 judges whether or not the MG target final torque T MG is equal to or greater than the slip control target torque TTRC. The slip control target torque TTRC is a target torque outputted by the slip control portion 104 according to the result of the slip control.

[0099] If the MG target final torque T MG is equal to or greater than the slip control target torque TTRC (step S501: YES), the process proceeds to step S502. If the MG target final torque T MG is not equal to or greater than the slip control target torque TTRC (step S501: NO), the process proceeds to step S505.

[0100] In step S502, the target setting portion 103 judges whether or not the vehicle body acceleration AV is equal to or less than 0. If the vehicle body acceleration AV is equal to or less than 0 (step S502: YES), the process proceeds to step S503. If the vehicle body acceleration AV is not equal to or less than 0 (step S502: NO), the process proceeds to step S505.

[0101] In step S503, the target setting portion 103 executes the correction prohibition process. At the time of executing the correction prohibition process, the slip control is prohibited. After the process of step S503 ends, the process proceeds to step S504.

[0102] In step S504, the target setting portion 103 sets the slip control prohibition flag XMYU to "1". In step S505, the target setting portion 103 sets the slip control prohibition flag XMYU to "0". After the processes of step S504 and step S505 end, the process returns.

[0103] [Supplementary Note] The following Supplementary Notes 1 to 7 can be arbitrarily combined as long as they are not technically contradictory.

[0104] [Supplementary Note 1] A control device, the control device 10 including: a coefficient estimation portion 105 that estimates a maximum friction coefficient μp of a road surface when a drive wheel is rotated by the drive wheel with respect to a moving body to travel on the road surface; a limit calculation portion 102 that calculates a torque upper limit for driving the drive wheel based on the estimated maximum friction coefficient μp; and a target setting portion 103 that sets a target torque for driving the drive wheel in a manner not exceeding the torque upper limit.

[0105] According to the sub-note 1, since the maximum friction coefficient μp is estimated and the torque upper limit is calculated, the drive wheel control can be performed using the maximum friction coefficient μp.

[0106] [Sub-note 2] The control device 10 according to the sub-note 1, wherein The coefficient estimation section 105 estimates the maximum friction coefficient at the time of acceleration of the moving body, that is, the acceleration friction coefficient, and the maximum friction coefficient at the time of deceleration of the moving body, that is, the deceleration friction coefficient. According to the sub-note 2, since the acceleration friction coefficient and the deceleration friction coefficient are estimated, the maximum friction coefficient μp can be estimated at the time of acceleration and at the time of deceleration, and the drive wheel control can be performed using the maximum friction coefficient μp in either case of acceleration and deceleration.

[0108] [Sub-note 3] The control device 10 according to the sub-note 2, wherein The limit calculation section 102 calculates the torque upper limit based on the acceleration friction coefficient or the deceleration friction coefficient that is most recently estimated by the coefficient estimation section 105.

[0109] According to the sub-note 3, since the deceleration friction coefficient estimated at the time of deceleration can be used as the maximum friction coefficient μp at the time of start, for example, even in a case where the estimation of the maximum friction coefficient μp cannot be completed in time at the time of start, the optimum acceleration and stability corresponding to the road surface friction coefficient μ can be obtained.

[0110] [Sub-note 4] The control device 10 according to the sub-note 3, wherein The coefficient estimation section 105 estimates an offset corresponding to a difference between the acceleration friction coefficient and the deceleration friction coefficient, The limit calculation section 102 adds the offset to the deceleration friction coefficient when calculating the torque upper limit based on the deceleration friction coefficient.

[0111] According to the sub-note 4, since the offset corresponding to the difference between the acceleration friction coefficient and the deceleration friction coefficient is estimated, and the torque upper limit is calculated by adding the offset to the deceleration friction coefficient, the maximum friction coefficient μp can be estimated with higher accuracy.

[0112] [Sub-note 5] The control device 10 according to any one of the sub-notes 1 to 4, wherein The limit calculation section 102 changes the torque upper limit in accordance with at least one of a slope of a road surface on which the moving body travels, a drive mode of the moving body, and a weight of the moving body.

[0113] [Sub-note 6] The control device according to any one of the supplementary notes 1 to 4, wherein The target setting unit 103 does not perform the setting of the target torque of the drive wheels based on the upper limit of the torque in a case where the moving body cannot accelerate.

[0114] [Supplementary Note 7] A program that causes a control device to perform the following actions: estimating a maximum friction coefficient of a road surface when the drive wheels are caused to rotate with respect to the moving body to travel on the road surface, calculating an upper limit of torque for driving the drive wheels based on the estimated maximum friction coefficient, setting a target torque for driving the drive wheels in a manner not exceeding the upper limit of the torque.

[0115] The control unit and the method thereof according to the present disclosure can also be realized by a special-purpose computer provided by a processor programmed to execute one or more functions embodied by a computer program, or a special-purpose computer provided by a processor composed of one or more special-purpose hardware logic circuits. Alternatively, the control unit and the method thereof according to the present disclosure can be realized by a special-purpose computer provided by a processor composed of one or more special-purpose hardware logic circuits, or a combination of a processor programmed to execute one or more functions and a processor composed of one or more hardware logic circuits. Furthermore, the computer program can be stored in a non-transitory tangible recording medium readable by a computer as instructions to be executed by the computer.

[0116] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Even if a person skilled in the art makes appropriate design changes to these specific examples, as long as the features of the present disclosure are included, it is included in the scope of the present disclosure. The elements included in each of the above-described specific examples and their arrangement, conditions, shape, and the like are not limited to the illustrated cases and can be appropriately changed. As long as there is no technical contradiction, each element included in the above-described specific examples can be appropriately combined and changed.

Claims

1. A control device, comprising: The coefficient estimation unit (105) estimates the maximum coefficient of friction of the road surface when the drive wheel rotates relative to the moving body and travels on the road surface. Limit calculation unit (102) calculates the upper limit of the torque driving the drive wheel based on the estimated maximum friction coefficient; as well as The target setting unit (103) sets the target torque for driving the drive wheel in a manner that does not exceed the upper limit of the torque.

2. The control device as described in claim 1, characterized in that, The coefficient estimation unit estimates the maximum friction coefficient (acceleration friction coefficient) when the moving body accelerates and the maximum friction coefficient (deceleration friction coefficient) when the moving body decelerates.

3. The control device as described in claim 2, characterized in that, The limit calculation unit calculates the upper limit of torque based on the acceleration friction coefficient or the deceleration friction coefficient most recently estimated by the coefficient estimation unit.

4. The control device as described in claim 3, characterized in that, The coefficient estimation unit estimates the offset corresponding to the difference between the acceleration friction coefficient and the deceleration friction coefficient. When calculating the upper limit of torque based on the deceleration friction coefficient, the limit calculation unit adds the offset to the deceleration friction coefficient.

5. The control device as described in any one of claims 1 to 4, characterized in that, The limit calculation unit changes the upper limit of torque based on at least one of the slope of the road surface on which the mobile body travels, the driving mode of the mobile body, and the weight of the mobile body.

6. The control device as described in any one of claims 1 to 4, characterized in that, If the moving body cannot accelerate, the target setting unit does not set a target torque based on the upper limit of torque.

7. A program, The program causes the control device to perform the following actions: The maximum coefficient of friction of the road surface is estimated when the drive wheel rotates relative to the moving body and travels on the road surface. The upper limit of the torque driving the drive wheel is calculated based on the estimated maximum coefficient of friction. The target torque for driving the drive wheel is set in a manner that does not exceed the upper limit of the torque.

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