In-vehicle system and vehicle braking system

Abstract

The present invention relates to an in-vehicle system and a vehicle braking system. The vehicle braking system includes a brake provided on a wheel of the vehicle to suppress rotation of the wheel, and a braking force control device that controls the braking force of the brake. The braking force control device includes a road surface state acquisition unit that acquires a road surface state which is a state of a road surface on which the vehicle travels. When the road surface state acquisition unit acquires the road surface state as a plurality of states, the braking force is controlled in a form different from the control of each braking force based on each of the plurality of states.

Description

Technical Field

[0001] The present invention relates to a vehicle-mounted system that controls a vehicle-mounted device mounted on a vehicle based on the state of a road surface. Background Art

[0002] Japanese Patent No. 6034378 describes a vehicle-mounted system that controls an engine, a braking mechanism, a suspension, etc. based on the road surface state. In this vehicle-mounted system, the control mode of the engine, etc. is determined to be one of a grass / gravel / snow control mode, a mud / rut control mode, a rock / boulder control mode, etc. based on the road surface state. The control mode is determined to be a mode with higher accuracy determined based on a plurality of parameters indicating the road surface state. Specifically, as described in paragraphs

[0058] to

[0070] of Japanese Patent No. 6034378, when the vehicle speed is small, the accuracy that the road surface state is a rocky area is high. Therefore, when the vehicle speed is small, the accuracy of the rock / boulder control mode is set to 0.7, and when the vehicle speed is large, it is set to 0.2. In this way, in each control mode, the accuracy for each of the plurality of parameters is determined respectively, and based on these accuracies, a composite accuracy value is obtained, and the control mode with the highest composite accuracy value is determined to be the optimal control mode based on the road surface state at that time. Summary of the Invention

[0003] An object of the present invention is to suppress a significant decrease in the starting performance of a vehicle in a vehicle-mounted system.

[0004] In the vehicle-mounted system according to the present invention, when a road surface state acquisition unit acquires a plurality of road surface states, a control different from the control based on each state of the acquired plurality of road surface states is performed. This is because there is a high possibility that the state of the road surface is not accurately recognized by the road surface state acquisition unit. For example, when a plurality of road surface states are acquired and control based on one of the plurality of road surface states is performed, when the actual road surface state is a state closer to another road surface state than one of the plurality of road surface states, there is a case where the starting performance of the vehicle is significantly reduced. In contrast, when performing control based on, for example, a road surface state in the middle of a plurality of road surface states different from the plurality of road surface states, or control in the middle of the control based on each state of the plurality of road surface states, even if the road surface state is a state close to any of the plurality of states, a significant decrease in the starting performance of the vehicle can be suppressed.

[0005] Furthermore, the passability is, for example, a function that can travel according to the driver's intention, a function that can suppress being immobilized during driving, and the starting performance is, for example, a function that can start well, a function that can suppress being immobilized during driving.

[0006] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings, in which like reference numerals represent like elements. Description of the Drawings

[0007] Figure 1 It is a top view schematically showing the configuration of the vehicle-mounted system.

[0008] Figure 2A It is a view showing the state of a vehicle equipped with the above vehicle-mounted system traveling, and is a view showing the state of the vehicle traveling in a rocky area.

[0009] Figure 2B It is a view showing the state of a vehicle equipped with the above vehicle-mounted system traveling, and is a view showing the state of the vehicle traveling on sand.

[0010] Figure 2C It is a view showing the state of a vehicle equipped with the above vehicle-mounted system traveling, and is a view showing the state of the vehicle traveling in a muddy area.

[0011] Figure 3 It is a flowchart showing the braking force control program stored in the brake ECU of the above vehicle-mounted system.

[0012] Figure 4 It is a flowchart showing a part (S1) of the above program.

[0013] Figure 5 It is a flowchart showing a part (S2) of the above program. Detailed Description of the Invention

[0014] Hereinafter, an example of a vehicle-mounted system as an embodiment of the present invention will be described in detail based on the drawings.

[0015] In Figure 1 an example of a vehicle-mounted system mounted on a vehicle Vh is shown. The vehicle Vh is a four-wheel drive vehicle, and the left and right front wheels 12FL, 12FR and the left and right rear wheels 14RL, 14RR are drive wheels. The vehicle-mounted system includes a drive and transmission device 8, a braking mechanism 10, etc. The drive and transmission device 8 includes a drive device, a transmission, a transmission device, etc., and the above drive device includes at least one of an engine and an electric motor. The output of the drive and transmission device 8 is transmitted to the left and right front wheels 12FL, 12FR via a differential device 20, drive shafts 22FL, 22FR, and is transmitted to the left and right rear wheels 14RL, 14RR via a transmission shaft 24, a differential device 26, drive shafts 28RL, 28RR.

[0016] The differential device 20 distributes the output torque of the drive and transmission device 8 to the left and right drive wheels 12FL and 12FR, and allows a rotational speed difference therebetween. If the rotation of one of the left and right drive wheels 12FL and 12FR is locked, the output torque of the drive and transmission device 8 applied to the other drive wheel increases. The same applies to the differential device 26, which distributes the rotational torque of the propeller shaft 24 to the left and right drive wheels 14RL and 14RR and allows a rotational speed difference therebetween.

[0017] The braking mechanism 10 includes friction brakes 32FL, 32FR, 34RL, 34RR that are respectively provided on the left and right front wheels 12FL, 12FR and the left and right rear wheels 14RL, 14RR and inhibit the rotation of the wheels, a master cylinder 38, a brake actuator 36, etc. The friction brakes 32FL, 32FR, 34RL, 34RR press the friction engagement members against the brake rotors that can rotate together with the wheels by hydraulic pressure or electromagnetic force, etc., thereby inhibiting the rotation of the wheels. In this embodiment, the friction brakes 32FL, 32FR, 34RL, 34RR can operate by hydraulic pressure.

[0018] The master cylinder 38 generates hydraulic pressure due to the operation of the brake pedal 40 that is a brake operation member. In addition, it is detected by the brake switch 42 whether the brake pedal 40 has been operated.

[0019] The brake actuator 36 is provided between the master cylinder 38 and the friction brakes 32, 34. The brake actuator 36 includes a power-type hydraulic source such as a pump device and a plurality of solenoid valves. Even when the brake pedal 40 is not operated, hydraulic pressure can be generated by the operation of the pump device. In addition, by controlling the plurality of solenoid valves, the hydraulic pressure as the pushing force in each of the friction brakes 32FL, 32FR, 34RL, 34RR is independently controlled based on the hydraulic pressure of the master cylinder 38 or the hydraulic pressure generated by the pump device.

[0020] Hereinafter, for the friction brakes and the like, when there is no need to distinguish by wheel position or in the case of a general term, etc., the reference numerals FL, FR, RL, RR indicating the wheel position are omitted from the description.

[0021] In this vehicle-mounted system, a control device 50 mainly composed of a computer is included. The brake switch 42, wheel speed sensors 52FL, 52FR, 52RL, 52RR, an acceleration sensor (hereinafter, there are cases where it is simply referred to as a G sensor. It is also described as a G sensor in the drawings) 54, an accelerator opening sensor 56, an off-road switch 58, a drive and transmission state acquisition device 60, etc. are connected to the control device 50, and the brake actuator 36, etc. are also connected.

[0022] Wheel speed sensors 52 are respectively provided on each wheel 12, 14, and independently detect the rotational speeds of the wheels 12, 14. In the control device 50, based on the detection values of the wheel speed sensors 52, the rotational accelerations of the wheels 12, 14 and the traveling speed of the vehicle Vh are obtained. The G sensor 54 can be, for example, a gyro sensor, and detects the acceleration in the front-rear direction of the vehicle Vh (sometimes simply referred to as front-rear G) and the acceleration in the lateral direction (sometimes simply referred to as lateral G). The accelerator opening sensor 56 detects the operation state of an accelerator pedal (not shown). When the depression amount of the accelerator pedal is large, the accelerator opening becomes larger compared to the case where it is small.

[0023] The off-road switch 58 can be operated by the driver. In the ON state, when driving in the wild, control of the braking force based on the road surface condition is permitted. The drive / torque transmission state acquisition device 60 detects the operating state of the drive / torque transmission device 8, for example, detects the engine speed and the shift position of the transmission. In the control device 50, based on the engine speed, the shift position of the transmission, etc., the driving force applied to the vehicle Vh is obtained, and the front-rear G is inferred. The front-rear G inferred by the control device 50 is referred to as the inferred front-rear G.

[0024] In the vehicle-mounted system configured as described above, when the off-road switch 58 is in the ON state during the vehicle Vh driving in the wild, control of the braking force based on the road surface condition is performed. In the control device 50, based on the traveling state of the vehicle Vh, the road surface condition of the place where the vehicle Vh travels is obtained. The traveling state of the vehicle Vh can be represented by the detection values of the wheel speed sensors 52, the detection values of the G sensor 54, the operating state of the drive / torque transmission device 8, etc. Moreover, based on the obtained road surface condition, the brake actuator 36, etc. are controlled. Hereinafter, in the wild, there are cases of driving in places that are not roads, but for convenience, the ground of places that are not roads is also referred to as the road surface.

[0025] In the control device 50, for example, as Figure 2A 、 Figure 2B and Figure 2C shown, it is determined whether the road surface condition of the place where the vehicle Vh travels is a rocky area (recorded as Rock in Figure 2A ), whether it is a muddy area (recorded as Mud in Figure 2C ), and whether it is a sandy area (recorded as Sand in Figure 2B ).

[0026] As Figure 2AAs shown, the Rock area is a place where there are rocks and large stones. In the Rock area, it is difficult for the vehicle Vh to travel at a high speed, and the vehicle body is prone to tilting, and the lateral G is likely to increase. Therefore, when the traveling speed of the vehicle Vh is less than the set speed and the lateral G is greater than the set lateral G, it is determined that the road surface condition is the Rock area. In addition, when traveling in the Rock area, the brake pedal 40 is often operated, so the condition that the brake switch 42 is in the on state can also be added to the conditions for determining that the road surface condition is the Rock area.

[0027] As Figure 2B shown, the Sand area is a place with a lot of gravel. The gravel includes a large amount of sand and small stones. In the Sand area, the vehicle Vh is prone to skidding, and the actual longitudinal and lateral G as the actual longitudinal and lateral acceleration is likely to be smaller than the inferred longitudinal and lateral G. Therefore, when the value obtained by subtracting the actual longitudinal and lateral G, which is the actual longitudinal and lateral acceleration of the vehicle Vh detected by the G sensor 54, from the inferred longitudinal and lateral G of the vehicle Vh inferred from the operating state of the drive and transmission device 8 detected by the drive and transmission state acquisition device 60, etc., is equal to or greater than the set value, it is determined that it is the Sand area.

[0028] As Figure 2C shown, the Mud area is muddy. In the Mud area, the degree of mud is usually uneven, so the amplitude of the change in the rotational acceleration of the wheels 12 and 14 of the vehicle Vh is likely to increase. Therefore, when the amplitude of the change in the wheel acceleration is equal to or greater than the set value, it is determined that the road surface condition is the Mud area.

[0029] In addition, if the small stones included in the Sand area are compared with the rocks and stones included in the Rock area, the rocks and stones included in the Rock area are larger. The rocks and stones included in the Rock area are of a size such that the lateral G is equal to or greater than the set value.

[0030] On the other hand, for example, when the vehicle Vh is traveling in the Rock area, when the wheels 12 and 14 are in contact with the rocks and when they are away from the rocks, there are cases where the rotational acceleration of the wheels changes significantly, resulting in cases where it is determined that the road surface condition is the Mud area. In addition, when the Mud area is tilted, the traveling speed of the vehicle Vh is low, and there are cases where the lateral G is greater than the set lateral G, resulting in cases where it is determined that the road surface condition is the Rock area. In these cases, it is determined that the road surface condition is both the Rock area and the Mud area. Similarly, there are also cases where it is determined that the road surface condition is both the Rock area and the Sand area.

[0031] In addition, when the vehicle Vh is traveling in a muddy area and is unable to move, there is a case where the actual front-rear G becomes smaller than the inferred front-rear G, resulting in a situation where the road surface condition is determined to be sandy. In this case, there is a situation where the road surface condition is determined to be both a muddy area and a sandy area.

[0032] As for the control of the braking force, traction control is performed based on the acquired road surface condition. In a state where the driver has stepped on an accelerator pedal (not shown) (the accelerator opening detected by the accelerator opening sensor 56 is greater than the set opening), when the driving slip, which is the slip of at least one of the wheels 12 and 14, becomes equal to or greater than a set state (for example, the driving slip rate is equal to or greater than a set value), traction control is performed. In traction control, even if the brake pedal 40 is not stepped on, the friction brakes 32 and 34 can be operated by the brake actuator 36 to apply a braking force to the wheels 12 and 14. The driving force (driving torque) applied to the wheels 12 and 14 is suppressed, and the driving slip is suppressed.

[0033] In traction control, when the road surface condition is a rocky area, a larger braking force is applied to the wheel with a larger driving slip. For example, there is a case where one of the left and right driving wheels (for example, the left rear wheel 14RL) leaves the rock surface and idles. In this case, by strongly suppressing the rotation of the idling wheel (the left rear wheel 14RL), the driving torque applied to the other wheel (the right rear wheel 14RR) can be increased. As a result, the passability or starting performance of the vehicle Vh in the rocky area can be improved. This control mode is called the lock-up mode.

[0034] In traction control, when the road surface condition is a muddy area or a sandy area, the braking force applied to the wheel with a larger driving slip is smaller than the braking force in the case where the road surface condition is a rocky area. This is because in a muddy area or a sandy area, the driving slip of the wheels 12 and 14 tends to increase, but compared with suppressing the driving slip, applying a larger driving force to the wheels 12 and 14 can improve the passability or starting performance. This control mode is called the muddy mode or the sandy mode.

[0035] In this embodiment, in the case where the road surface condition is determined to be (rocky area and muddy area), or in the case where it is determined to be (rocky area and sandy area), or in the case where it is determined to be (rocky area and muddy area and sandy area), in traction control, the braking force of the friction brake applied to the wheel with a larger driving slip is controlled to be the intermediate value between the braking force applied when the road surface condition is a rocky area and the braking force applied when it is a muddy area or a sandy area. This is because, in the case where it is determined to be a rocky area and at least one of a muddy area and a sandy area, it can be considered that the road surface condition has not been accurately obtained. This control mode is called the MTSoff mode.

[0036] MTS (Multi Terrain Select) refers to the control of in-vehicle devices that determines whether the road surface condition is one of the pre-determined (rocky area, muddy area, sandy area), or is based on one of the obtained (rocky area, muddy area, sandy area). In contrast, in this embodiment, in the case where the road surface condition is determined to be (rocky area and muddy area), or in the case where it is determined to be (rocky area and sandy area), or in the case where it is determined to be (rocky area and muddy area and sandy area), since the road surface condition is in the MTSoff state or not suitable for control based on any one of (rocky area, muddy area, sandy area), it can be considered that MTS is turned off.

[0037] In addition, it can be considered that the control corresponding to the MTSoff mode is control based on the road surface condition of MTSoff, that is, the intermediate road surface condition between a rocky area and a muddy area and a sandy area (or a state that can be called different from any one of a rocky area, a muddy area, and a sandy area), and is considered to be control corresponding to the intermediate control mode between the lock-up mode, the muddy mode, and the sandy mode (or a control mode different from any one of the lock-up mode, the muddy mode, and the sandy mode), etc. Also, in the case where multiple road surface conditions are obtained, it can be considered that this road surface condition is not suitable for the so-called MTS control, that is, it is obtained as the MTSoff state, and the control mode set based on the obtained MTSoff road surface condition is the MTSoff mode.

[0038] On the other hand, in a conventional vehicle-mounted system, when it is determined that the road surface condition is a plurality of conditions including a rocky area (for example, it is a rocky area and at least one of a muddy area and a sandy area), a lock-up mode that applies a relatively large braking force is set from the perspective of safety. However, when the road surface condition is not a rocky area, there is a problem that the passability and startability of the vehicle Vh deteriorate. In contrast, in the present embodiment, when it is determined that the road surface condition is a plurality of conditions including a rocky area, an MTSoff mode, which is a control mode intermediate between the lock-up mode, the muddy mode, and the sandy mode, is set as the lock-up mode. Thus, even when the road surface condition is not a rocky area, a significant decrease in the passability and startability of the vehicle Vh can be suppressed.

[0039] In addition, in traction control, when the accelerator opening detected by the accelerator opening sensor 56 is equal to or greater than a set opening and the traveling speed of the vehicle is equal to or less than a set speed, it is presumed that the braking force control is not suitable for the road surface condition. Therefore, in this case, even if any one of the lock-up mode, the muddy mode, and the sandy mode is set, the mode is switched to the MTSoff mode.

[0040] In the present embodiment, the braking force control program represented by the Figure 3 flowchart is executed at every predetermined set time. In step 1 (hereinafter simply referred to as S1; the same applies to other steps), the road surface condition is obtained, and in S2, traction control, which is control of the braking force, is performed based on the obtained road surface condition.

[0041] According to the Figure 4 flowchart, the road surface condition in S1 is obtained. In S11, the longitudinal G and lateral G are obtained by the G sensor 54, the wheel speeds of the respective wheels 12, 14 are obtained by the wheel speed sensors 52, and the operating state of the drive / transmission device 8 is obtained by the drive / transmission state acquisition device 60. In S12, the estimated longitudinal G is obtained based on the operating state of the drive / transmission device 8, the traveling speed VS is obtained based on the wheel speeds of the respective wheels 12, 14, and the respective rotational accelerations VWG of the wheels 12, 14 are obtained. In S13, it is determined whether the traveling speed VS is less than the set speed VSth and whether the lateral G is greater than the set lateral G. If the determination in S13 is affirmative, in S14, it is determined that the road surface condition is a rocky area. Next, in S15, it is determined whether the absolute value of the value obtained by subtracting the actual longitudinal G from the estimated longitudinal G is greater than the set value Gth. If the determination in S15 is affirmative, in S16, it is determined that the road surface condition is a sandy area. Next, in S17, it is determined whether the amplitude of the rotational acceleration of at least one of the four wheels is greater than the set value, and if the determination is affirmative, in S18, it is determined that the road surface condition is a muddy area.

[0042] Thus, in this embodiment, when the respective conditions of S13, 15, and 17 are satisfied, the road surface state is obtained in any one of the rocky area, sandy area, and muddy area. Therefore, there is a case where two or more of the rocky area, sandy area, and muddy area are repeatedly obtained as the road surface state.

[0043] According to Figure 4 the flowchart of, the control of the braking force in S2 is determined. In S21, it is determined whether the obtained road surface state is a plurality of states including the rocky area (the rocky area, and at least one of the muddy area and the sandy area), in other words, it is determined whether it is (rocky area and muddy area) or (rocky area and sandy area) or (rocky area, muddy area, and sandy area). In S22, it is determined whether it is the rocky area. In S23, it is determined whether it is the muddy area, or whether it is (muddy area and sandy area). In S24, it is determined whether it is the sandy area.

[0044] When the obtained road surface state is the rocky area, the determination in S22 is yes. In S25, it is obtained that the road surface state for control is the rocky area, and the control mode is determined to be the lock-up mode.

[0045] When the obtained road surface state is the muddy area or (muddy area and sandy area), the determination in S23 is yes. In S26, it is obtained that the road surface state for control is the muddy area, and the control mode is determined to be the muddy mode. Thus, when the road surface state is (muddy area and sandy area), the muddy mode based on the muddy area is set as the control mode. This is because when controlling based on the sandy mode in the muddy area and when controlling based on the muddy mode in the sandy area, compared with the latter case, the passability and starting performance of the former are reduced more significantly.

[0046] When the obtained road surface state is the sandy area, the determination in S24 is yes. In S27, it is obtained that the road surface state for control is the sandy area, and the sandy mode is determined.

[0047] In addition, when the obtained road surface state is a plurality of states including the rocky area (the rocky area, and at least one of the muddy area and the sandy area), the determination in S21 is yes. In S28, it is determined that the road surface state for control is MTSoff, and the control mode is determined to be the MTSoff mode. When all the determinations in S21 to S24 are no, in S29, it is also determined that the road surface state for control is MTSoff, and the MTSoff mode is determined.

[0048] In addition, in S30, traction control is performed based on the control mode determined in S25 to 29. When the control mode is the lock-up mode, a greater braking force is applied to the wheel with a larger driving slip. When the control mode is the mud mode or the sand mode, the braking force applied to the wheel with a larger driving slip is smaller than that in the case where the lock-up mode is set. In contrast, in the case of the MTS off mode, the braking force is controlled in a control mode intermediate between the lock-up mode and the mud mode / sand mode. The braking force applied to the wheel with a larger driving slip is controlled to be of a magnitude intermediate between that in the case of the lock-up mode and that in the case of the mud mode / sand mode. That is, the braking force applied to the wheel with a driving slip equal to or greater than the set state by the friction brake is less than the braking force in the case of the lock-up mode and greater than the braking force in the case of the mud mode / sand mode. As a result, when the road surface state is MTS off, it is possible to suppress a significant reduction in the passability and startability of the vehicle regardless of whether the actual road surface state is close to a rocky area or close to a muddy area or a sandy area.

[0049] As described above, in the present embodiment, a part of the braking force control program represented by the flowchart stored in the control device 50, a part that executes the braking force control program, etc. constitute the braking force control device. A part that stores S1, a part that executes S1, etc. in the braking force control device constitute the road surface state acquisition unit. A part that stores S25 to 29, a part that executes S25 to 29, etc. constitute the control road surface state determination unit and the control mode determination unit. Figure 3

[0050] In addition, in the above-described embodiment, the case of controlling the braking mechanism 10 based on the state of the road surface has been described, but it can also be applied to the case of controlling in-vehicle devices such as the drive / transmission device 8 and the suspension.

[0051] In addition, in the above-described embodiment, the road surface state is acquired based on the detection values of the G sensor 54, the wheel speed sensor 52, the drive / transmission state acquisition device 60, etc., but in addition to this, it can also be acquired based on the detection value of the vehicle height sensor, the image acquired based on an in-vehicle camera, laser, etc.

[0052] In addition to the above-described embodiment, the present invention can also be implemented in various ways in which various changes and improvements have been made based on the knowledge of those skilled in the art.

[0053] (1) A braking system for a vehicle, comprising a brake provided on a wheel of the vehicle and suppressing rotation of the above-mentioned wheel, and a braking force control device for controlling the braking force of the above-mentioned brake, wherein the above-mentioned braking force control device includes a road surface state acquisition unit that acquires the state of the road surface as the state of the road surface on which the above-mentioned vehicle travels, and when the above-mentioned road surface state is acquired as a plurality of states by the above-mentioned road surface state acquisition unit, the braking force is controlled in a form different from the control of each braking force based on each of the above-mentioned plurality of states.

[0054] For example, when it is acquired that the road surface state is a plurality of states, the braking force can be controlled with an intensity that is the average of the intensities of the control of the braking force based on each of the plurality of states.

[0055] The road surface state acquisition unit can acquire the road surface state based on the driving state of the vehicle, or can also acquire the road surface state based on image data acquired by a camera or the like, information acquired by a radar or the like, etc. For example, the road surface state can be acquired based on the driving speed of the vehicle, the skidding state of the wheels, etc.

[0056] (2) The braking system for a vehicle according to item (1), wherein the above-mentioned road surface state acquisition unit is an acquisition unit that acquires the above-mentioned road surface state as a first state and a second state, and when it is acquired by the above-mentioned road surface state acquisition unit that the above-mentioned road surface state is the above-mentioned first state and the above-mentioned second state, the above-mentioned braking force control device controls the braking force in a form different from the control of the braking force based on the above-mentioned first state and the control of the braking force based on the above-mentioned second state.

[0057] (3) The braking system for a vehicle according to item (2), wherein the above-mentioned braking force control device is configured such that when the above-mentioned road surface state acquired by the above-mentioned road surface state acquisition unit is the above-mentioned first state, compared with the case where the above-mentioned road surface state acquired by the above-mentioned road surface state acquisition unit is the above-mentioned second state, a control for making the above-mentioned braking force stronger is performed, and when the above-mentioned road surface state acquired by the above-mentioned road surface state acquisition unit is the above-mentioned first state and the above-mentioned second state, the braking force is controlled to be an intermediate intensity between the intensity of the braking force in the case of the above-mentioned first state and the intensity of the braking force in the case of the above-mentioned second state.

[0058] When it is acquired by the road surface state acquisition unit that the road surface state is the first state and the second state, the braking force can be controlled to be weaker than the intensity of the braking force in the case of the first state and stronger than the intensity of the braking force in the case of the second state. For example, it can be controlled with an average magnitude of the braking force in the case of the first state and the braking force in the case of the second state, etc.

[0059] (4) The vehicle braking system according to item (2) or (3), wherein the first state is a rocky area and the second state is a sandy or muddy area.

[0060] (5) The vehicle braking system according to any one of items (1) to (4), wherein the braking force control device includes a control mode determination unit that determines a control mode based on the road surface state obtained by the road surface state acquisition unit, and controls the braking force based on the control mode determined by the control mode determination unit.

[0061] (6) The vehicle braking system according to item (5), wherein the road surface state acquisition unit is an acquisition unit that acquires the road surface state as the first state and the second state. When the road surface state obtained by the road surface state acquisition unit is the first state and the second state, the control mode determination unit determines the third control mode, which is a control mode different from the first control mode corresponding to the first state and the second control mode corresponding to the second state. The braking force controlled in the third control mode is the intermediate value between the magnitude of the braking force controlled in the first control mode and the magnitude of the braking force controlled in the second control mode.

[0062] The third control mode corresponds to the MTS off mode in the above embodiment.

[0063] (7) The vehicle braking system according to any one of items (1) to (6), wherein the braking force control device includes a traction control unit that suppresses the slip of the wheels when the vehicle is driven by controlling the braking force.

[0064] (8) The vehicle braking system according to any one of items (1) to (7), wherein the braking force control device includes a control road surface state determination unit that determines a control road surface state based on the road surface state obtained by the road surface state acquisition unit, and controls the braking force based on the control road surface state determined by the control road surface state determination unit. When the road surface state obtained by the road surface state acquisition unit is a plurality of states, the control road surface state determination unit determines a state different from the plurality of states.

[0065] The road surface state acquisition unit can also be called a temporary road surface state acquisition unit, and the road surface state obtained by the road surface state acquisition unit can be called a temporary road surface state. The control road surface state is obtained based on the temporary road surface state. There are cases where the temporary road surface state is the control road surface state, but when a plurality of temporary road surface states are obtained, a state different from the plurality of temporary road surface states is the control road surface state.

[0066] (9) The vehicle braking system according to item (8), wherein the road surface state acquisition unit is an acquisition unit that acquires that the road surface state is the first state and the second state. When the road surface state acquired by the road surface state acquisition unit is the first state and the second state, the control road surface state determination unit determines the road surface state as the third state, which is the road surface state intermediate between the first state and the second state.

[0067] For example, when the first state is a rocky area and the second state is a muddy area, it can be determined that the third state is the road surface state intermediate between the rocky area and the muddy area (for example, a rocky area with relatively small unevenness, a muddy area close to an asphalt road surface). In addition, it can be considered as a road surface state that is generally not suitable for off-road-based road surface state control (a state close to an asphalt road).

[0068] (10) A vehicle-mounted system includes a vehicle-mounted device mounted on a vehicle and capable of controlling the driving state of the vehicle, and a control device for controlling the vehicle-mounted device. The control device includes a road surface state acquisition unit that acquires the state of the road surface on which the vehicle travels. When a plurality of the road surface states are acquired by the road surface state acquisition unit, the vehicle-mounted device is controlled in a form different from the control of each vehicle-mounted device based on each of the plurality of road surface states.

[0069] The technical features described in any one of items (1) to (9) can be applied to the vehicle-mounted system described in this item.

[0070] As the vehicle-mounted device, there are drive devices for driving the vehicle, etc. In traction control, the control of the driving force can be carried out instead of, or in parallel with, the control of the braking force. In addition, as the vehicle-mounted device, it can also be a suspension device, etc.

Claims

1. A braking system for a vehicle, comprising: a brake disposed on a wheel of the vehicle and suppressing rotation of the wheel; and a braking force control device that controls a braking force of the brake, wherein the braking force control device includes a road surface state acquisition unit that acquires a road surface state which is a state of a road surface on which the vehicle travels, and when the road surface state is acquired as a plurality of states by the road surface state acquisition unit, controls the braking force in a form different from control of each braking force based on each of the plurality of states; the road surface state acquisition unit is an acquisition unit that acquires the road surface state as a first state and a second state; the braking force control device is configured to: when the road surface state acquired by the road surface state acquisition unit is the first state, perform control to make the braking force stronger than when the road surface state acquired by the road surface state acquisition unit is the second state, and when the road surface state acquired by the road surface state acquisition unit is both the first state and the second state, control the braking force to an intermediate strength between the strength of the braking force when it is the first state and the strength of the braking force when it is the second state.

2. The braking system for a vehicle according to claim 1, wherein the first state is a rocky area; the second state is a sandy area or a muddy area.

3. The braking system for a vehicle according to claim 1, wherein the braking force control device includes a control mode determination unit that determines a control mode based on the road surface state acquired by the road surface state acquisition unit, and controls the braking force based on the control mode determined by the control mode determination unit; when the road surface state acquired by the road surface state acquisition unit is both the first state and the second state, the control mode determination unit determines a third control mode, which is a control mode different from a first control mode that is a control mode corresponding to the first state and a second control mode that is a control mode corresponding to the second state; the braking force controlled in the third control mode is an intermediate value between the magnitude of the braking force controlled in the first control mode and the magnitude of the braking force controlled in the second control mode.

4. The braking system for a vehicle according to claim 1, wherein the braking force control device includes a control road surface state determination unit that determines a control road surface state based on the road surface state acquired by the road surface state acquisition unit, and controls the braking force based on the control road surface state determined by the control road surface state determination unit; when the road surface state acquired by the road surface state acquisition unit is both the first state and the second state, the control road surface state determination unit determines the road surface state as a third state that is an intermediate road surface state between the first state and the second state.

5. The braking system for a vehicle according to any one of claims 1 to 4, wherein The braking force control device includes a traction control unit that suppresses slip of the wheel during driving of the vehicle by controlling the braking force.

Images