Road surface determination device and vehicle control device

Abstract

To determine whether or not a road surface on which a vehicle travels is a wavy road.SOLUTION: The road surface determination device 80 includes a derivation unit 81 configured to derive an estimated vehicle body speed based on at least one of a wheel speed of a front wheel 12F and a wheel speed of a rear wheel 12R, a first determination unit 82 configured to determine whether a first condition is satisfied, the first condition indicating that a wheel acceleration of the front wheel 12F has changed by a first determination value or more, and a second determination unit 83 configured to determine whether a second condition is satisfied, the second condition indicating that an increase tendency of the estimated vehicle body speed has continued for a predetermined measurement time after the first condition is satisfied. And the road surface determination unit 85 configured to determine that the road surface is a wavy road when the first condition, the second condition, and the third condition are satisfied. The third determination unit 84 is configured to determine whether the third condition is satisfied. 12R.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a road surface judgment device applied to a vehicle, and a vehicle control device equipped with the road surface judgment device. [Background technology]

[0002] Patent Document 1 discloses an example of a control device that can prevent anti-lock brake control from starting when a wheel passes over a bump. The control device determines that the wheel speed has suddenly decreased when at least one of the following three conditions is met:

[0003] - The instantaneous value of wheel acceleration is below a specified value. The rate of change in wheel acceleration is less than a specified rate of change. The difference between the wheel acceleration value filtered by a specified method and the instantaneous wheel acceleration value is greater than a specified value.

[0004] When the control device determines that the wheel speed has suddenly decreased, it determines that the wheel has passed over a step. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-301600 Summary of the Invention [Problem to be solved by the invention]

[0006] Vehicles may travel on undulating roads. When a vehicle travels on undulating roads, the wheel speed is likely to change. However, the amount of change in wheel speed when a vehicle travels on an undulating road is smaller than the amount of change in wheel speed when a wheel passes over a bump. Therefore, the above-mentioned control device cannot determine whether the road surface on which the vehicle is traveling is an undulating road. [Means for solving the problem]

[0007] A road surface judgment device for solving the above problem is applied to a vehicle having front and rear wheels. The road surface judgment device includes: a derivation unit that derives an estimated vehicle body speed that is an estimate of the vehicle body speed based on at least one of the wheel speeds of the front wheels and the wheel speeds of the rear wheels; a first judgment unit that judges whether a first condition is satisfied that indicates that the wheel acceleration of the front wheels has fluctuated by a first judgment value or more; a second judgment unit that judges whether a second condition is satisfied that indicates that the estimated vehicle body speed has continued to show an increasing trend for a predetermined measurement time after the first condition is satisfied; a third judgment unit that judges whether a third condition is satisfied that indicates that the wheel acceleration of the rear wheels has fluctuated by a second judgment value or more after the second condition is satisfied; and a road surface judgment unit that judges that the road surface on which the vehicle is traveling is an undulating road when the first condition, the second condition, and the third condition are satisfied.

[0008] A vehicle control device for solving the above problem includes the road surface determination device and controls the braking force generated at the front wheels and the braking force generated at the rear wheels. The derivation unit derives the estimated vehicle body speed so that the amount of decrease in the estimated vehicle body speed per unit time does not exceed a lower limit guard. The vehicle control device also includes a guard setting unit that executes a change process to increase the lower limit guard when the road surface is determined to be an undulating road compared to when the road surface is determined not to be an undulating road. [Effects of the Invention]

[0009] To determine whether or not the road surface on which a vehicle is traveling is an undulating road. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing an outline of a vehicle equipped with a vehicle control device according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the vehicle and the vehicle control device of FIG. [Figure 3]FIG. 3 is a schematic diagram showing the vehicle of FIG. 1 traveling on an undulating road. [Figure 4] FIG. 4 is a schematic diagram showing the vehicle of FIG. 1 traveling on an undulating road. [Figure 5] FIG. 5 is a schematic diagram showing the vehicle of FIG. 1 traveling on an undulating road. [Figure 6] FIG. 6 is a timing chart when the vehicle of FIG. 1 is traveling on an undulating road. [Figure 7] FIG. 7 is a flowchart showing the flow of processing for determining whether or not the road surface is an undulating road in the vehicle control device of FIG. [Figure 8] FIG. 8 is a flowchart showing the flow of processing for deriving an estimated vehicle body speed in the vehicle control device of FIG. [Figure 9] FIG. 9 is a flowchart showing a process flow for setting a lower limit guard in the vehicle control device of FIG. [Figure 10] FIG. 10 is a flowchart showing a process flow for setting the intervention threshold for antilock brake control in the vehicle control device of FIG. [Figure 11] FIG. 11 is a timing chart when the vehicle of FIG. 1 is traveling on an undulating road. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of a road surface judgment device and a vehicle control device will be described with reference to FIGS. 1 and 2 show a vehicle 10 equipped with a vehicle control device 40. <Vehicle configuration> For example, the vehicle 10 is a motorcycle. The vehicle 10 includes a body 11, one front wheel 12F, and one rear wheel 12R. A front suspension 13 is interposed between the front wheel 12F and the body 11. A swing arm 14 is interposed between the rear wheel 12R and the body 11.

[0012] As shown in FIG. 2, the vehicle 10 is equipped with brake operating members that are operated by the driver of the vehicle 10 when decelerating the vehicle 10. The brake operating members include a front wheel brake operating member 15F and a rear wheel brake operating member 15R. The front wheel brake operating member 15F is operated by the driver when generating a braking force on the front wheels 12F. The rear wheel brake operating member 15R is operated by the driver when generating a braking force on the rear wheels 12R. An example of the front wheel brake operating member 15F is a brake lever. An example of the rear wheel brake operating member 15R is a brake pedal.

[0013] The vehicle 10 is equipped with a front wheel friction brake 20F, a rear wheel friction brake 20R, and a brake actuator 25. The front wheel friction brake 20F is provided for the front wheel 12F. The rear wheel friction brake 20R is provided for the rear wheel 12R. The front wheel friction brake 20F and the rear wheel friction brake 20R each have a wheel cylinder 21. A brake fluid is supplied to the wheel cylinder 21 of the front wheel friction brake 20F at an amount corresponding to the amount of operation of the front wheel brake operating member 15F by the driver. A brake fluid is supplied to the wheel cylinder 21 of the rear wheel friction brake 20R at an amount corresponding to the amount of operation of the rear wheel brake operating member 15R by the driver. The front wheel friction brake 20F generates a braking force on the front wheel 12F corresponding to the fluid pressure in the wheel cylinder 21. The rear wheel friction brake 20R generates a braking force on the rear wheel 12R corresponding to the fluid pressure in the wheel cylinder 21.

[0014] The brake actuator 25 is configured to be able to individually adjust the hydraulic pressure of the multiple wheel cylinders 21. When deceleration slip occurs in a wheel, antilock brake control is executed to eliminate the deceleration slip of that wheel. Hereinafter, antilock brake control will be referred to as "ABS control." When ABS control is executed, the brake actuator 25 adjusts the hydraulic pressure of the wheel cylinder 21 corresponding to the wheel that is the target of the ABS control. An example of the brake actuator 25 is the device disclosed in Japanese Patent Application Laid-Open No. 2018-52404.

[0015] <Sensors> The vehicle 10 is equipped with a plurality of sensors that output detection signals according to the detection results to the vehicle control device 40. The plurality of sensors includes, for example, a front wheel speed sensor 31, a rear wheel speed sensor 32, and an acceleration sensor 33. The front wheel speed sensor 31 detects the rotation speed of the front wheels 12F. The rear wheel speed sensor 32 detects the rotation speed of the rear wheels 12R. The acceleration sensor 33 detects the longitudinal acceleration of the vehicle 10.

[0016] The rotation speed of the front wheels 12F derived by applying known filtering to the detection signal of the front wheel speed sensor 31 is the front wheel speed VWF. The rotation speed of the rear wheels 12R derived by applying known filtering to the detection signal of the rear wheel speed sensor 32 is the rear wheel speed VWR. The acceleration derived by applying known filtering to the detection signal of the acceleration sensor 33 is the longitudinal acceleration GX.

[0017] <Vehicle control device> The vehicle control device 40 includes a processing circuit 41. One example of the processing circuit 41 is an electronic control device. In this case, the processing circuit 41 includes a CPU 42, a first memory 43, and a second memory 44. The first memory 43 stores a control program executed by the CPU 42. The second memory 44 stores the results of calculations by the CPU 42. The processing circuit 41 activates the brake actuator 25 by the CPU 42 executing the control program in the first memory 43.

[0018] <About undulating roads> 3 to 6, the transitions of various parameters of the vehicle 10 when the vehicle 10 travels on an undulating road 100 will be described. The undulating road 100 is a road surface that has irregular undulations like waves, as shown in FIG.

[0019] FIG. 3 shows a first state of the vehicle 10 in which the front wheel 12F has entered a depression 101 on the undulating road 100. FIG. 4 shows a second state of the vehicle 10 in which the front wheel 12F has passed through the depression 101. FIG. 5 shows a third state of the vehicle 10 in which the rear wheel 12R has entered the depression 101. FIG. 6A shows the transitions of the front wheel speed VWF, the rear wheel speed VWR, and the estimated vehicle speed VS0 when the vehicle 10 is traveling on the undulating road 100. FIG. 6B shows the transitions of the front wheel acceleration DVWF when the vehicle 10 is traveling on the undulating road 100. FIG. 6C shows the transitions of the rear wheel acceleration DVWR when the vehicle 10 is traveling on the undulating road 100. The estimated vehicle speed VS0 is an estimated value of the vehicle speed of the vehicle 10 derived based on at least one of the front wheel speed VWF and the rear wheel speed VWR. Vehicle speed is the rotational speed of the wheels, which corresponds to the vehicle speed. Front wheel acceleration DVWF is the wheel acceleration of the front wheels 12F. Rear wheel acceleration DVWR is the wheel acceleration of the rear wheels 12R. For example, the value obtained by differentiating the front wheel speed VWF with respect to time is the front wheel acceleration DVWF. The value obtained by differentiating the rear wheel speed VWR with respect to time is the rear wheel acceleration DVWR.

[0020] In the example shown in FIG. 6, the state of the vehicle 10 from timing t10 ​​to timing t11 is state 1. When the front wheel 12F enters a depression 101 on the undulating road 100, the front wheel speed VWF fluctuates as shown by the dashed line in FIG. 6A in accordance with the extension and contraction of the front suspension 13. That is, the front suspension 13 first contracts, causing the front wheel 12F to move closer to the vehicle body 11. As a result, the front wheel speed VWF decreases significantly. Thereafter, when the front suspension 13 begins to extend, the front wheel 12F moves away from the vehicle body 11 in accordance with the extension of the front suspension 13. As a result, the front wheel speed VWF increases. That is, the front wheel speed VWF oscillates in accordance with the extension of the front suspension 13.

[0021] Furthermore, when the state of the vehicle 10 is the first state, the rear wheel 12R is not in the recess 101, but the swing arm 14 is actuated by the influence of the unevenness of the road surface. When the swing arm 14 is actuated, the rear wheel 12R moves away from the vehicle body 11 or moves closer to the vehicle body 11 depending on the actuation of the swing arm 14. As a result, some fluctuations also occur in the rear wheel speed VWR.

[0022] 6, the estimated vehicle speed VS0 is calculated based on the larger of the front wheel speed VWF and the rear wheel speed VWR. That is, when the front wheel speed VWF is equal to or greater than the rear wheel speed VWR, the estimated vehicle speed VS0 is calculated based on the front wheel speed VWF. When the front wheel speed VWF is smaller than the rear wheel speed VWR, the estimated vehicle speed VS0 is calculated based on the rear wheel speed VWR.

[0023] Therefore, when the state of the vehicle 10 is the first state, the front wheel speed VWF and the rear wheel speed VWR fluctuate, and therefore the estimated vehicle body speed VS0 also fluctuates. When the front wheel 12F passes through the recess 101, the state of the vehicle 10 transitions from the first state to the second state. In the example shown in Fig. 6, the state of the vehicle 10 from timing t11 to timing t12 is the second state. When the state of the vehicle 10 is the second state, both the front wheel speed VWF and the rear wheel speed VWR generally increase, as shown in Fig. 6(A).

[0024] When the vehicle 10 is in the second state and moves forward, the front wheel 12F moves in accordance with the road surface due to the extension of the front suspension 13. Similarly, the rear wheel 12R moves in accordance with the road surface due to the operation of the swing arm 14. Therefore, both the front wheel speed VWF and the rear wheel speed VWR continue to increase. As a result, when the vehicle 10 is in the second state, the estimated vehicle speed VS0 continues to increase.

[0025] Thereafter, when the rear wheel 12R enters the recessed portion 101, the state of the vehicle 10 transitions from the second state to the third state. The state of the vehicle 10 from timing t12 to timing t13 is the third state. As shown in (A) of FIG. 6, the front wheel speed VWF, the rear wheel speed VWR, and the estimated vehicle body speed VS0 increase at timing t12. After timing t12, the front wheel speed VWF and the rear wheel speed VWR decrease. Specifically, when the rear wheel 12R enters the recessed portion 101, the rear wheel speed VWR fluctuates as shown by the two-dot chain line in (A) of FIG. 6 in accordance with the operation of the swing arm 14. That is, first, the rear wheel 12R moves relatively away from the vehicle body 11 due to the operation of the swing arm 14. As a result, the rear wheel speed VWR decreases significantly. Thereafter, the rear wheel 12R moves relatively closer to the vehicle body 11 due to the operation of the swing arm 14. As a result, the rear wheel speed VWR increases. That is, the rear wheel speed VWR oscillates in response to the operation of the swing arm 14.

[0026] Furthermore, when the state of the vehicle 10 is the third state, the front wheel 12F passes through the recess 101, but the front suspension 13 gradually contracts due to the influence of the unevenness of the road surface. As a result, the front wheel speed VWF also decreases.

[0027] The estimated vehicle body speed VS0 is derived based on the front wheel speed VWF and the rear wheel speed VWR. Therefore, after timing t12, the estimated vehicle body speed VS0 also decreases. However, as will be described in detail later, upper and lower limit guards are set in the derivation of the estimated vehicle body speed VS0. That is, the estimated vehicle body speed VS0 is derived so that the decrease in the estimated vehicle body speed VS0 per unit time does not exceed the lower limit guard. The estimated vehicle body speed VS0 is derived so that the increase in the estimated vehicle body speed VS0 per unit time does not exceed the upper limit guard. Therefore, when the decrease in the front wheel speed VWF and the rear wheel speed VWR per unit time is relatively large, as occurs after timing t12, a large deviation may occur between the front wheel speed VWF and the rear wheel speed VWR and the estimated vehicle body speed VS0.

[0028] Here, the value obtained by subtracting the front wheel speed VWF from the estimated vehicle body speed VS0 is the slip amount SLPF of the front wheel 12F. The value obtained by subtracting the rear wheel speed VWR from the estimated vehicle body speed VS0 is the slip amount SLPR of the rear wheel 12R.

[0029] During the period from timing t12 to timing t14, even though deceleration slippage is not actually occurring in either the front wheel 12F or the rear wheel 12R, the slip amount SLPF of the front wheel 12F and the slip amount SLPR of the rear wheel 12R become relatively large. When the slip amount SLPF exceeds the ABS control intervention threshold SLPth, ABS control for the front wheel 12F is initiated. When the slip amount SLPR exceeds the ABS control intervention threshold SLPth, ABS control for the rear wheel 12R is initiated. In other words, when the vehicle 10 is traveling on an undulating road 100, there is a risk that ABS control will be unnecessarily executed.

[0030] <Functional section> 2, the CPU 42 executes the control program in the first memory 43, causing the processing circuit 41 to function as multiple functional units. The multiple functional units include a functional unit for determining whether the road surface on which the vehicle 10 is traveling is an undulating road 100, and a functional unit for activating the brake actuator 25. For example, the multiple functional units include a derivation unit 81, a first determination unit 82, a second determination unit 83, a third determination unit 84, and a road surface determination unit 85. Furthermore, the multiple functional units include a guard setting unit 86, a change unit 87, and a braking control unit 88. In this embodiment, the derivation unit 81, the first determination unit 82, the second determination unit 83, the third determination unit 84, and the road surface determination unit 85 constitute an example of a "road surface determination device 80."

[0031] <Derivation part> The derivation unit 81 derives the estimated vehicle body speed VS0 based on at least one of the front wheel speed VWF and the rear wheel speed VWR at each predetermined control cycle. When the vehicle is braking, the derivation unit 81 derives the estimated vehicle body speed VS0 based on the larger of the front wheel speed VWF and the rear wheel speed VWR. When the vehicle 10 is not braking, the derivation unit 81 derives the estimated vehicle body speed VS0 based on the smaller of the front wheel speed VWF and the rear wheel speed VWR. A specific example of the process of deriving the estimated vehicle body speed VS0 will be described later.

[0032] <First judgment part> When the front wheel 12F enters a recess 101 while the vehicle 10 is traveling on an undulating road 100, that is, when the state of the vehicle 10 changes to the first state, the front wheel acceleration DVWF fluctuates greatly as shown in FIG. 6(B).

[0033] Therefore, the first determination unit 82 determines whether a first condition indicating that the front wheel acceleration DVWF has fluctuated by a first determination value or more is satisfied. For example, if all of the following conditions (A1), (A2), and (A3) are satisfied, the first determination unit 82 determines that the first condition is satisfied. On the other hand, if at least one of the conditions (A1), (A2), and (A3) is not satisfied, the first determination unit 82 determines that the first condition is not satisfied.

[0034] (A1) ABS control is not being executed with the front wheel 12F as the wheel to be controlled. (A2) The front wheel acceleration DVWF is greater than the front wheel acceleration judgment value DVWth1. (A3) The increase ΔDVWF of the front wheel acceleration DVWF at a predetermined first judgment time is greater than the first judgment increase ΔDVWFth.

[0035] A positive value is set as the front wheel acceleration determination value DVWth1. The criterion for determining whether the front wheel acceleration DVWF has increased is set as the front wheel acceleration determination value DVWth1. The front wheel acceleration DVWF is derived for each predetermined control cycle. For example, the length of time for N control cycles is set as the first determination time. "N" is an integer greater than or equal to 1. An example of "N" is 4.

[0036] <Second judgment part> When the state of the vehicle 10 transitions from the first state to the second state, the estimated vehicle speed VS0 continues to show an increasing trend as shown in FIG. 6(A).

[0037] Therefore, the second determination unit 83 determines whether or not the second condition is satisfied after the first condition is satisfied. The second condition is that the estimated vehicle speed VS0 continues to show an increasing tendency for a predetermined measurement time TMk.

[0038] Here, when the vehicle 10 is traveling on a low μ road and both ABS control for the front wheels 12F and ABS control for the rear wheels 12R are executed, the front wheel speed VWF and the rear wheel speed VWR both increase, which may cause the estimated vehicle speed VSO to increase. However, in this case, the increase in the estimated vehicle speed VSO continues for a relatively short period of time. Therefore, the measurement time TMk is set to a time that can eliminate cases in which the estimated vehicle speed VSO continues to show an increasing trend for such reasons.

[0039] For example, the second determination unit 83 determines that the second condition is met when both of the following conditions (B1) and (B2) are met. (B1) The front wheel speed VWF continues to show an increasing trend during the measurement time TMk.

[0040] (B2) The rear wheel speed VWR continues to show an increasing trend during the measurement time TMk. As described above, the front wheel speed VWF is derived by applying known filtering to the detection signal of the front wheel speed sensor 31. The rear wheel speed VWR is derived by applying known filtering to the detection signal of the rear wheel speed sensor 32. Therefore, the second determination unit 83 may determine that the second condition is met when both the front wheel speed VWF and the rear wheel speed VWR continue to increase during the measurement time TMk.

[0041] <Third judgment part> When the vehicle 10 travels on the undulating road 100, after the rear wheel 12R enters the recess 101, the rear wheel acceleration DVWR fluctuates greatly as shown in FIG. 6(C).

[0042] Therefore, the third determination unit 84 determines whether a third condition, which indicates that the rear wheel acceleration DVWR has fluctuated by a value equal to or greater than a second determination value, is satisfied after the second condition is satisfied. The second determination value may be set to the same value as the first determination value, or may be set to a value different from the first determination value. For example, if all of the following conditions (C1), (C2), (C3), and (C4) are satisfied, the third determination unit 84 determines that the third condition is satisfied. On the other hand, if at least one of the conditions (C1) to (C4) is not satisfied, the third determination unit 84 determines that the third condition is not satisfied.

[0043] (C1) The time elapsed since the first condition was met is equal to or longer than the first reference time TMb1. (C2) The time elapsed since the first condition was met is within the second reference time TMb2.

[0044] (C3) The rear wheel acceleration DVWR is smaller than the rear wheel acceleration judgment value DVWth2. (C4) The decrease amount ΔDVWR of the rear wheel acceleration DVWR at a predetermined second judgment time is greater than the second judgment decrease amount ΔDVWRth.

[0045] The first reference time TMb1 is a time that can be derived using the following relational expression (D1). The second reference time TMb2 is a time that can be derived using the following relational expression (D2). In the relational expressions (D1) and (D2), "HB" is the wheelbase length of the vehicle 10. The gain α1 is smaller than the gain α2. For example, a value greater than 0 and less than 1 is set for the gain α1. A value greater than 1 and less than 2 is set for the gain α2. Therefore, the period in which both conditions (C1) and (C2) are met can be said to be a period in which the rear wheel 12R may be entering the recess 101 that the front wheel 12F has passed through.

[0046] TMb1 = (HB / VS0) × α1 …(D1) TMb2 = (HB / VS0) × α2 …(D2) A negative value is set as the rear wheel acceleration determination value DVWth2. The rear wheel acceleration determination value DVWth2 is set as a criterion for determining whether the absolute value of the rear wheel acceleration DVWR has increased. The rear wheel acceleration DVWR is derived for each predetermined control cycle. For example, the length of time for N control cycles is set as the second determination time. "N" is an integer greater than or equal to 1. An example of "N" is 4.

[0047] <Road surface judgment section> The road surface determination unit 85 determines that the road surface on which the vehicle 10 is traveling is an undulating road 100 when the first condition, the second condition, and the third condition are met.

[0048] <Guard setting section> When the road surface is determined to be an undulating road 100, the guard setting unit 86 executes a change process to increase the lower limit guard compared to when the road surface is determined not to be an undulating road 100. The lower limit guard is a parameter used to derive the estimated vehicle speed VS0. The guard setting unit 86 executes the change process until a predetermined switching period has elapsed. The switching period is the period from the time when the road surface is determined to be an undulating road 100 until a predetermined switching time TMc has elapsed. The change process will be described in detail later.

[0049] <Braking control unit> When deceleration slip occurs in at least one of the front wheels 12F and the rear wheels 12R, the braking control unit 88 starts ABS control to adjust the braking force generated in the wheel where deceleration slip occurs. Specifically, when the slip amount SLPF of the front wheels 12F exceeds the intervention threshold SLPth, the braking control unit 88 starts ABS control to adjust the braking force generated in the front wheels 12F. When the slip amount SLPR of the rear wheels 12R exceeds the intervention threshold SLPth, the braking control unit 88 starts ABS control to adjust the braking force generated in the rear wheels 12R. In ABS control, the braking control unit 88 operates the brake actuator 25 to adjust the hydraulic pressure in the wheel cylinder 21 corresponding to the wheel to be controlled.

[0050] <Changed section> When the above-described change process is being executed, the change unit 87 changes the ABS control intervention condition to make it less likely that ABS control will be initiated compared to when the change process is not being executed. For example, the change unit 87 increases the ABS control intervention threshold SLPth to make it less likely that ABS control will be initiated.

[0051] <Undulating road detection processing> The flow of processing executed by the processing circuit 41 to determine whether or not the road surface is an undulating road 100 will be described with reference to Fig. 7. The flow of processing shown in Fig. 7 is the undulating road determination processing. The processing circuit 41 repeatedly executes the undulating road determination processing at every predetermined control cycle.

[0052] In step S11, the processing circuit 41 determines whether the estimated vehicle body speed VS0 is equal to or greater than the first vehicle body speed VSth1 and equal to or less than the second vehicle body speed VSth2. A value greater than the first vehicle body speed VSth1 is set as the second vehicle body speed VSth2. If the estimated vehicle body speed VS0 is too small, ABS control is not initiated. Therefore, the first vehicle body speed VSth1 is set as a criterion for determining whether the vehicle 10 is traveling at a speed at which ABS control cannot be initiated. The second vehicle body speed VSth2 is set as a criterion for determining whether the estimated vehicle body speed VS0 is high. Here, "the estimated vehicle body speed VS0 is high" means, for example, that the vehicle 10 is traveling at a speed at which it is considered difficult to travel on the undulating road 100. For example, a vehicle body speed between 20 km / h and 40 km / h is set as the second vehicle body speed VSth2. If the estimated vehicle body speed VS0 is less than the first vehicle body speed VSth1 (S11: NO), the processing circuit 41 temporarily terminates the undulating road determination process. If the estimated vehicle body speed VS0 is greater than the second vehicle body speed VSth2 (S11: NO), the processing circuit 41 temporarily terminates the undulating road determination process. On the other hand, if the estimated vehicle body speed VS0 is equal to or greater than the first vehicle body speed VSth1 and equal to or less than the second vehicle body speed VSth2 (S11: YES), the processing circuit 41 proceeds to step S13.

[0053] In step S13, the processing circuit 41 executes a first determination process by functioning as the first determination unit 82. In the first determination process, the processing circuit 41 determines whether the above-described conditions (A1) to (A3) are satisfied. After executing the first determination process, the processing circuit 41 proceeds to step S15.

[0054] In step S15, the processing circuit 41 functions as the first determination unit 82 to determine whether or not the first condition is met. The processing circuit 41 determines whether or not the first condition is met based on the execution result of the first determination process in step S13. If the processing circuit 41 determines that the first condition is met (S15: YES), the processing circuit 41 shifts the process to step S17. On the other hand, if the processing circuit 41 determines that the first condition is not met (S15: NO), the processing circuit 41 temporarily ends the undulating road determination process.

[0055] In step S17, the processing circuit 41 executes the second determination process by functioning as the second determination unit 83. In the second determination process, the processing circuit 41 determines whether the above-described conditions (B1) and (B2) are met. After executing the second determination process, the processing circuit 41 proceeds to step S19.

[0056] In step S19, the processing circuit 41 functions as the second determination unit 83 to determine whether or not the second condition is met. The processing circuit 41 determines whether or not the second condition is met based on the execution result of the second determination process in step S17. If the processing circuit 41 determines that the second condition is met (S19: YES), the processing circuit 41 shifts the process to step S21. On the other hand, if the processing circuit 41 determines that the second condition is not met (S19: NO), the processing circuit 41 temporarily ends the undulating road determination process.

[0057] In step S21, the processing circuit 41 executes a third determination process by functioning as the third determination unit 84. In the third determination process, the processing circuit 41 determines whether the above-described conditions (C1) to (C5) are satisfied. After executing the third determination process, the processing circuit 41 proceeds to step S23.

[0058] In step S23, the processing circuit 41 functions as the third determination unit 84 to determine whether or not the third condition is met. The processing circuit 41 determines whether or not the third condition is met based on the execution result of the third determination process in step S21. If the processing circuit 41 determines that the third condition is met (S23: YES), the processing circuit 41 shifts the process to step S25. On the other hand, if the processing circuit 41 determines that the third condition is not met (S23: NO), the processing circuit 41 temporarily ends the undulating road determination process.

[0059] In step S25, the processing circuit 41 functions as the road surface determination unit 85 and determines that the road surface is an undulating road 100. The processing circuit 41 sets a determination flag to ON. The determination flag is a flag that is set to ON when the road surface is determined to be an undulating road 100. Thereafter, the processing circuit 41 temporarily ends the undulating road determination process.

[0060] <Vehicle speed estimation processing> The flow of processing executed by the processing circuit 41 to derive the estimated vehicle body speed VS0 will be described with reference to Fig. 8. The flow of processing shown in Fig. 8 is the vehicle body speed estimation processing. The processing circuit 41 repeatedly executes the vehicle body speed estimation processing for each predetermined control period. The processing circuit 41 functions as a derivation unit 81 to execute a plurality of processes that constitute the vehicle body speed estimation processing.

[0061] In step S31, the processing circuit 41 derives a unit increment UVW, which is the increase per unit time in the wheel speed VW of the target wheel. The "target wheel" here refers to the wheel used to derive the estimated vehicle body speed VS0. When the vehicle 10 is braking, the wheel with the larger wheel speed VW, either the front wheel 12F or the rear wheel 12R, is the target wheel. When the vehicle 10 is not braking, the wheel with the smaller wheel speed VW, either the front wheel 12F or the rear wheel 12R, is the target wheel. The "unit time" here refers to the length of the derivation cycle of the estimated vehicle body speed VS0. For example, the processing circuit 41 can derive the unit increment UVW by subtracting the wheel speed VW of the target wheel in the previous control cycle from the current wheel speed VW of the target wheel. Therefore, when the wheel speed VW is increasing, the unit increment UVW is a positive value. On the other hand, when the wheel speed VW is decreasing, the unit increment UVW is a negative value.

[0062] In the next step S33, the processing circuit 41 selects one of the unit increment UVW, the upper increment UVWUL, and the lower increment UVWLL as the intermediate value UVWMD. The upper increment UVWUL is the upper limit of the increment of the estimated vehicle body speed VS0 permitted when deriving the estimated vehicle body speed VS0. The lower increment UVWLL is the lower limit of the increment of the estimated vehicle body speed VS0 permitted when deriving the estimated vehicle body speed VS0. In other words, the upper increment UVWUL corresponds to the above-mentioned upper limit guard. The lower increment UVWLL corresponds to the above-mentioned lower limit guard. For example, a value obtained by inverting the positive and negative of the upper increment UVWUL is set as the lower increment limit UVWLL. Alternatively, a value corresponding to the maximum deceleration that can be generated in the vehicle 10 by applying braking force on a specified road surface may be set as the lower increment limit UVWLL. The processing circuit 41 selects the second largest value among the three values ​​UVW, UWVUL, and UVWLL as the intermediate value UVWMD.

[0063] In the following step S35, the processing circuit 41 derives the sum of the estimated vehicle body speed VS0 and the intermediate value UVWMD as a provisional value VSK of the estimated vehicle body speed. In the next step S37, the processing circuit 41 determines whether the provisional value VSK is equal to or greater than 0 (zero). If the provisional value VSK is equal to or greater than 0 (zero) (S37: YES), the processing circuit 41 proceeds to step S39. On the other hand, if the provisional value VSK is less than 0 (zero) (S37: NO), that is, if the provisional value VSK is a negative value, the processing circuit 41 proceeds to step S41.

[0064] In step S39, the processing circuit 41 sets the tentative value VSK to the estimated vehicle speed VS0, and then the processing circuit 41 temporarily ends the vehicle speed estimation process. In step S41, the processing circuit 41 sets the estimated vehicle speed VS0 to 0 (zero), and then the processing circuit 41 temporarily ends the vehicle speed estimation process.

[0065] <Increase amount lower limit setting process> The flow of processing performed by the processing circuit 41 to set the increase amount lower limit UVWLL will be described with reference to Fig. 9. The flow of processing shown in Fig. 9 is the increase amount lower limit setting processing. The processing circuit 41 repeatedly executes the increase amount lower limit setting processing for each predetermined control period.

[0066] In step S51, the processing circuit 41 determines whether the above-mentioned determination flag is set to ON. If the determination flag is set to ON, it can be determined that the vehicle 10 is traveling on an undulating road 100. If the determination flag is set to ON (S51: YES), the processing circuit 41 proceeds to step S53. On the other hand, if the determination flag is not set to ON (S51: NO), the processing circuit 41 temporarily ends the increase amount lower limit setting process.

[0067] In step S53, the processing circuit 41, functioning as the guard setting unit 86, determines whether the switching period has ended. If the processing circuit 41 determines that the switching period has ended (S53: YES), the processing circuit 41 shifts the process to step S55. On the other hand, if the processing circuit 41 determines that the switching period has not ended (S53: NO), the processing circuit 41 shifts the process to step S59. In other words, if the present time is still within the switching period, the processing circuit 41 shifts the process to step S59.

[0068] In step S55, the processing circuit 41 functions as the guard setting unit 86 to set the first value UVW1 to the increment lower limit UVWLL. The first value UVW1 is a negative value. In the following step S57, the processing circuit 41 sets the determination flag to OFF. Thereafter, the processing circuit 41 temporarily ends the increment lower limit setting process.

[0069] In step S59, the processing circuit 41 executes a change process. In the change process, the processing circuit 41 sets the second value UVW2 as the increment lower limit UVWLL. The second value UVW2 is a negative value. The absolute value of the second value UVW2 is greater than the absolute value of the first value UVW1. That is, in the change process, the processing circuit 41 sets the increment lower limit UVWLL to a value that is smaller than when the change process is not executed. Thereafter, the processing circuit 41 temporarily ends the increment lower limit setting process.

[0070] <Threshold setting process> The flow of processing executed by the processing circuit 41 to set the intervention threshold SLPth will be described with reference to Fig. 10. The flow of processing shown in Fig. 10 is the threshold setting processing. When ABS control is not being executed, the processing circuit 41 repeatedly executes the threshold setting processing at every predetermined control period.

[0071] In step S71, the processing circuit 41 determines whether the above-mentioned determination flag is set to on. If the determination flag is set to on, it can be determined that the vehicle 10 is traveling on an undulating road 100. If the determination flag is set to on (S71: YES), the processing circuit 41 shifts the processing to step S73. On the other hand, if the determination flag is not set to on (S71: NO), the processing circuit 41 shifts the processing to step S75.

[0072] In step S73, the processing circuit 41 determines whether or not the change process is currently being executed. If the processing circuit 41 is not executing the change process (S73: NO), the processing circuit 41 proceeds to step S75. On the other hand, if the processing circuit 41 is executing the change process (S73: YES), the processing circuit 41 proceeds to step S77.

[0073] In step S75, the processing circuit 41 sets the first slip amount SLP1 to the intervention threshold value SLPth by functioning as the changing unit 87. After that, the processing circuit 41 temporarily ends the threshold value setting process.

[0074] In step S77, the processing circuit 41 functions as the changing unit 87 to set the second slip amount SLP2 as the intervention threshold value SLPth. The second slip amount SLP2 is greater than the first slip amount SLP1. In this way, the processing circuit 41 changes the intervention threshold value SLPth from the first slip amount SLP1 to the second slip amount SLP2. This allows the processing circuit 41 to change the ABS control intervention condition to make it less likely that ABS control will be initiated. Thereafter, the processing circuit 41 temporarily ends the threshold setting process.

[0075] <Actions and Effects of This Embodiment> The operation and effect of this embodiment will be described with reference to Fig. 11. The transitions of the front wheel speed VWF, rear wheel speed VWR, front wheel acceleration DVWF, and rear wheel acceleration DVWR in Fig. 11 are the same as those shown in Fig. 6.

[0076] As shown in (A), (B), and (C) of Figure 11, when a front wheel 12F of a traveling vehicle 10 enters a recess 101 on an undulating road 100, the state of the vehicle 10 changes to state 1. In the example shown in Figure 11, the state of the vehicle 10 is state 1 from timing t20 to timing t22. When the state of the vehicle 10 is state 1, the front wheel speed VWF fluctuates as shown by the dashed line in (A) of Figure 11, and the front wheel acceleration DVWF fluctuates as shown in (B) of Figure 11.

[0077] The processing circuit 41 determines whether the front wheel acceleration DVWF is greater than the front wheel acceleration determination value DVWth1. The processing circuit 41 determines whether the increase amount ΔDVWF of the front wheel acceleration is greater than the first determination increase amount ΔDVWFth. In the example shown in FIG. 11, the above conditions (A1), (A2), and (A3) are satisfied at time t21, so the processing circuit 41 determines that the first condition is satisfied. In other words, time t21 is the time point at which the first condition is satisfied.

[0078] Thereafter, at timing t22, the front wheel 12F passes through the recessed portion 101, and the state of the vehicle 10 changes to the second state. Then, as shown by the dashed line and the two-dot chain line in FIG. 11A, both the front wheel speed VWF and the rear wheel speed VWR continue to increase. The point in time when the measurement time TMk has elapsed since timing t22 is timing t23. In the example shown in FIG. 11, after timing t22, both the front wheel speed VWF and the rear wheel speed VWR continue to increase. That is, the increasing tendency of both the front wheel speed VWF and the rear wheel speed VWR continues for the measurement time TMk.

[0079] Therefore, the processing circuit 41 determines that the second condition is met at timing t23. Thereafter, at timing t25, the rear wheel 12R enters the recessed portion 101, causing the state of the vehicle 10 to transition from state 2 to state 3. In the example shown in Fig. 11, the state of the vehicle 10 is state 3 from timing t25 to timing t27. When the state of the vehicle 10 is state 3, the rear wheel speed VWR fluctuates as shown by the two-dot chain line in Fig. 11(A), and the rear wheel acceleration DVWR fluctuates as shown in Fig. 11(C).

[0080] 11, timing t24 between timing t23 and timing t25 is the time when the first reference time TMb1 has elapsed since timing t21, when the first condition was met, and timing t27, which comes after timing t25, is the time when the second reference time TMb2 has elapsed since timing t21, when the first condition was met.

[0081] The processing circuit 41 determines whether the rear wheel acceleration DVWR is smaller than the rear wheel acceleration determination value DVWth2. The processing circuit 41 determines whether the decrease amount ΔDVWR of the rear wheel acceleration is greater than the second determination decrease amount ΔDVWRth. In the example shown in FIG. 11, both of the above conditions (C3) and (C4) are satisfied at timing t26. Timing t26 is a point in time between timing t24 and timing t27. Therefore, the processing circuit 41 determines that the third condition is satisfied. In other words, timing t26 is the point in time when the third condition is satisfied.

[0082] Since the first condition, the second condition, and the third condition are met, the processing circuit 41 determines that the road surface is an undulating road 100. On the other hand, if at least one of the first condition, the second condition, and the third condition is not met, the processing circuit 41 determines that the road surface is not an undulating road 100. Therefore, the vehicle control device 40 can determine whether the road surface on which the vehicle 10 is traveling is an undulating road 100 or not.

[0083] In this embodiment, the following effects can be further obtained. (1) While the vehicle 10 is in the second state, both the front wheel speed VWF and the rear wheel speed VWR increase, and therefore the estimated vehicle speed VS0 also increases. However, when the vehicle 10 transitions from the second state to the third state, both the front wheel speed VWF and the rear wheel speed VWR decrease. Moreover, the rates of decrease in the front wheel speed VWF and the rear wheel speed VWR are relatively large.

[0084] Therefore, the processing circuit 41 executes a change process when it is determined that the road surface is an undulating road 100. In the change process, the processing circuit 41 increases the lower limit guard when deriving the estimated vehicle speed VS0 compared to when it is determined that the road surface is not an undulating road 100. Specifically, the processing circuit 41 increases the absolute value of the increment lower limit UVWLL compared to when it is determined that the road surface is not an undulating road 100.

[0085] In the example shown in FIG. 11, the change process is executed from timing t26 to timing t28. This allows the processing circuit 41 to reduce the estimated vehicle body speed VS0 at a speed that corresponds to the rate at which the front wheel speed VWF and the rear wheel speed VWR are reduced. As a result, the processing circuit 41 can prevent the slip amount SLPF of the front wheels 12F from increasing when deceleration slip is not actually occurring in the front wheels 12F. The processing circuit 41 can prevent the slip amount SLPR of the rear wheels 12R from increasing when deceleration slip is not actually occurring in the rear wheels 12R. Therefore, the vehicle control device 40 can prevent ABS control from being initiated even when deceleration slip is not occurring in the wheels.

[0086] (2) During the gear shift process, the processing circuit 41 changes the ABS control intervention condition to make it less likely that ABS control will be initiated, compared to when the change process is not being executed. Specifically, during the gear shift process, the processing circuit 41 increases the intervention threshold SLPth, compared to when the change process is not being executed. This allows the vehicle control device 40 to more effectively prevent ABS control from being initiated even when deceleration slip does not occur in the wheels.

[0087] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0088] If the processing circuit 41 executes the change process when it is determined that the road surface is an undulating road 100, it is not necessary to change the intervention threshold value SLPth of the ABS control. If the processing circuit 41 increases the intervention threshold SLPth for ABS control when it determines that the road surface is an undulating road 100, it does not need to execute the change processing when it determines that the road surface is an undulating road 100.

[0089] When the vehicle control device 40 determines that the road surface on which the vehicle 10 is traveling is an undulating road 100, the vehicle control device 40 may execute a process to transmit information indicating that the road surface is an undulating road 100 together with location information of the road surface to a server outside the vehicle. The vehicle control device 40 may also execute a process to transmit the information to other vehicles traveling near the vehicle 10.

[0090] In the above embodiment, the control device that controls the brake actuator 25 functions as the road surface determination device 80, but this is not limited to this. For example, a control device that controls the brake actuator 25 and a control device that functions as the road surface determination device 80 may be provided separately. In other words, the vehicle control device 40 may be configured to include a control device that controls the brake actuator 25 and a control device that functions as the road surface determination device 80.

[0091] The processing circuit 41 may determine whether the third condition is met based on a condition different from the conditions described in the above embodiment. For example, if all of the conditions (C1), (C2), and (C3) are met, the processing circuit 41 may determine that the third condition is met, regardless of whether the condition (C4) is met.

[0092] The processing circuit 41 may determine whether the second condition is satisfied based on a condition different from the condition described in the above embodiment. For example, the processing circuit 41 may determine that the second condition is satisfied when the state in which the estimated vehicle speed VS0 increases continues for a measurement time TMk.

[0093] The processing circuitry 41 may determine whether the first condition is met based on a condition different from the conditions described in the above embodiment. For example, if both of the conditions (A1) and (A2) are met, the processing circuitry 41 may determine that the first condition is met, regardless of whether the condition (A3) is met.

[0094] The vehicle to which the vehicle control device 40 is applied may be different from the vehicle 10 shown in FIG. 1 as long as it has at least one front wheel and at least one rear wheel. For example, the vehicle to which the vehicle control device 40 is applied may be a vehicle having two front wheels and one rear wheel. The vehicle to which the vehicle control device 40 is applied may be a vehicle having one front wheel and two rear wheels. The vehicle to which the vehicle control device 40 is applied may be a vehicle having two front wheels and two rear wheels.

[0095] In the above embodiment, a braking force corresponding to the amount of operation of the front wheel brake operating member 15F by the driver is generated in the front wheel friction brake 20F, and a braking force corresponding to the amount of operation of the rear wheel brake operating member 15R by the driver is generated in the rear wheel friction brake 20R, but this is not limited to this. For example, the vehicle may be equipped with a so-called integral brake. The integral brake can distribute and generate a braking force corresponding to the amount of operation of the front wheel brake operating member 15F by the driver to the front wheel friction brake 20F and the rear wheel friction brake 20R, or can distribute and generate a braking force corresponding to the amount of operation of the rear wheel brake operating member 15R by the driver to the front wheel friction brake 20F and the rear wheel friction brake 20R.

[0096] The processing circuit 41 is not limited to a circuit having a CPU and ROM and executing software processing. In other words, the processing circuit 41 may have any one of the following configurations (a), (b), and (c):

[0097] (a) The processing circuit 41 includes one or more processors that execute various processes according to a computer program. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to execute processes. Memory, i.e., computer-readable media, includes any available media that can be accessed by a general-purpose or special-purpose computer.

[0098] (b) The processing circuit 41 includes one or more dedicated hardware circuits that perform various processes. Examples of dedicated hardware circuits include application-specific integrated circuits, i.e., ASICs or FPGAs. ASIC is an abbreviation for "Application Specific Integrated Circuit." FPGA is an abbreviation for "Field Programmable Gate Array."

[0099] (c) The processing circuitry 41 includes one or more processors that execute some of the various processes in accordance with a computer program, and one or more dedicated hardware circuits that execute the remaining processes among the various processes.

[0100] <Other technical ideas> The technical ideas that can be understood from the above-described embodiment and modified examples will be described. [Appendix 1] A vehicle control device including the road surface judgment device and controlling a braking force generated at the front wheels and a braking force generated at the rear wheels, a braking control unit that starts antilock brake control to adjust the braking force generated at at least one of the front wheels and the rear wheels when deceleration slip occurs at that wheel; a change unit that, when the road surface is determined to be an undulating road, changes the intervention condition for the antilock brake control to a condition that makes it less likely that the antilock brake control will be initiated compared to a case where the road surface is determined not to be an undulating road.

[0101] The expression "at least one" used herein means "one or more" of the desired options. As an example, the expression "at least one" used herein means "only one option" or "both of two options" if the number of options is two. As another example, the expression "at least one" used herein means "only one option" or "any combination of two or more options" if the number of options is three or more. [Explanation of symbols]

[0102] 10...Vehicle 12F…Front wheel 12R…Rear wheel 40...Vehicle control device 41...Processing circuit 80…Road surface determination device 81...Derivation part 82...1st judgment section 83…Second judgment section 84...Third judgment section 85...Road surface judgment section 86...Guard setting section 87...Change section 88...Braking control unit 100...Undulating road

Claims

1. A road surface judgment device applied to a vehicle having front and rear wheels, a derivation unit that derives an estimated vehicle body speed, which is an estimated value of a vehicle body speed of the vehicle, based on at least one of the wheel speed of the front wheels and the wheel speed of the rear wheels; a first determination unit that determines whether a first condition indicating that the wheel acceleration of the front wheels has changed by a first determination value or more is established; a second determination unit that determines whether a second condition is satisfied, which indicates that the estimated vehicle speed has continued to show an increasing tendency for a predetermined measurement time after the first condition is satisfied; and a third determination unit that determines whether or not a third condition is satisfied, the third condition indicating that the wheel acceleration of the rear wheels has changed by a second determination value or more after the second condition is satisfied; a road surface determination unit that determines that the road surface on which the vehicle is traveling is an undulating road when the first condition, the second condition, and the third condition are met. Road surface determination device.

2. The second determination unit determines that the second condition is met when the wheel speed of both the front wheels and the wheel speed of the rear wheels continues to increase during the measurement time. The road surface judgment device according to claim 1 .

3. 3. A vehicle control device comprising the road surface judgment device according to claim 1 or 2, and configured to control braking forces generated at the front wheels and braking forces generated at the rear wheels, the derivation unit derives the estimated vehicle body speed so that a decrease in the estimated vehicle body speed per unit time does not exceed a lower limit guard, The vehicle control device includes: and a guard setting unit that, when the road surface is determined to be an undulating road, executes a change process to increase the lower limit guard compared to when the road surface is determined not to be an undulating road. Vehicle control device.

4. a braking control unit that starts antilock brake control to adjust the braking force generated at at least one of the front wheels and the rear wheels when deceleration slip occurs at that wheel; a change unit that, when the change process is being executed, changes the antilock brake control intervention condition to a side that makes it less likely that the antilock brake control will be initiated compared to a case where the change process is not being executed. The vehicle control device according to claim 3.

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