Control system, saddle-riding-type vehicle, control method, and program

Abstract

This control system of a saddle-riding-type vehicle comprises: a first detection part that detects speed in a vehicle vertical direction and angular velocity in a pitch direction generated in a vehicle body of the saddle-riding-type vehicle; a second detection part that detects a state change of a front suspension mechanism for supporting a front wheel of the saddle-riding-type vehicle; and a control part that controls the saddle-riding-type vehicle on the basis of detection results of the first detection part and the second detection part.

Description

Control system, saddle-ride type vehicle, control method, and program

[0001] The present invention relates to a vehicle control technology.

[0002] In recent years, efforts to provide access to sustainable transportation systems that take into consideration vulnerable traffic participants, such as the elderly, people with disabilities, and children, have been gaining momentum. To achieve this, research and development efforts are being focused on further improving traffic safety and convenience through development of vehicle behavior stability. Patent Document 1 discloses a system that outputs rear wheel damping force corresponding to the amount of stroke displacement on the front wheels at a timing determined based on the stroke displacement on the front wheels and the longitudinal acceleration of the vehicle body.

[0003] Japanese Unexamined Patent Publication No. 62-103215

[0004] In straddle-type vehicles, in order to achieve both improved behavioral stability (ride comfort) and reduced vehicle costs, it is necessary to provide a stroke sensor only for the front suspension and to accurately control the rear suspension, etc. based on the output of the stroke sensor.

[0005] Therefore, an object of the present invention is to provide a technology that can improve the behavioral stability of a saddle-type vehicle and reduce vehicle costs by detecting the vertical velocity and pitch angular velocity generated in the body of the saddle-type vehicle and enabling control of the vehicle, thereby contributing to the development of a sustainable transportation system.

[0006] In order to achieve the above object, a control system according to one aspect of the present invention is a control system for a saddle-riding type vehicle, characterized in that it comprises: a first detection unit that detects the vertical velocity and pitch angular velocity of the vehicle body of the saddle-riding type vehicle; a second detection unit that detects changes in the state of a front suspension mechanism that supports the front wheels of the saddle-riding type vehicle; and a control unit that controls the saddle-riding type vehicle based on the detection results of the first detection unit and the second detection unit.

[0007] According to the present invention, for example, it is possible to provide a technology that can improve the behavioral stability of a saddle-type vehicle while reducing vehicle costs by detecting the vertical velocity and pitch angular velocity generated in the body of the saddle-type vehicle and making it possible to control the vehicle.

[0008] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals.

[0009] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0010] FIG. 1 is a left side view showing a saddle-ride type vehicle in the first embodiment; FIG. 2 is a diagram showing an example of the configuration of a control system in the first embodiment; FIG. 3 is a diagram showing models of a front suspension mechanism and a rear suspension mechanism in the first embodiment; FIG. 4 is a diagram for explaining the relationship between a front wheel ground load Fzf and a reference force vector Fz in the first embodiment; FIG. 5 is a diagram for explaining the relationship between a rear wheel ground load Fzr and a reference force vector Fz in the first embodiment; FIG. 10 is a diagram showing an example of a damping force map; FIG. 11 is a diagram showing an example of a provisional current value map; FIG. 12 is a diagram showing an example of a limit current value map;

[0011] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be combined in any desired manner. Furthermore, the same reference numerals are used to designate identical or similar components, and redundant descriptions will be omitted.

[0012] First Embodiment A first embodiment of the present invention will be described. FIG. 1 is a left side view of a saddle-riding vehicle 1 according to this embodiment. In FIG. 1, arrows X, Y, and Z indicate directions that are perpendicular to one another, with the X direction indicating the front-to-rear direction of the saddle-riding vehicle 1 (vehicle longitudinal direction), the Y direction indicating the left-to-right direction of the saddle-riding vehicle 1 (vehicle width direction), and the Z direction indicating the up-to-down direction of the saddle-riding vehicle 1 (vehicle vertical direction). Below, an example will be described in which a control system according to the present invention is applied to a motorcycle as the saddle-riding vehicle 1. However, the control system according to the present invention can also be applied to other types of saddle-riding vehicles, such as tricycles, and can also be applied to electric vehicles using a motor as a drive source, in addition to vehicles using an internal combustion engine as a drive source. In the following, the saddle-riding vehicle 1 will sometimes be referred to as "vehicle 1."

[0013] The vehicle 1 includes front wheels FW, rear wheels RW, and a power unit 2. The power unit 2 includes an engine 21 and a transmission 22. The driving force of the transmission 22 is transmitted to the rear wheels RW via a drive shaft (not shown), causing the rear wheels RW to rotate.

[0014] The power unit 2 is supported by a body frame 3. The body frame 3 includes a pair of left and right main frames 31 extending in the X direction. A fuel tank 5 and an air cleaner box (not shown) are disposed above the main frames 31. A meter unit MU that displays various information to the rider is provided in front of the fuel tank 5.

[0015] A head pipe 32 that rotatably supports a steering shaft (not shown) that is turned by the handlebars 8 is provided at the front end of the main frame 31. A pair of left and right pivot plates 33 is provided at the rear end of the main frame 31. The lower ends of the pivot plates 33 are connected to the front end of the main frame 31 by a pair of left and right lower arms (not shown), and the power unit 2 is supported by the main frame 31 and the lower arms. In addition, a pair of left and right seat rails (not shown) that extend rearward are provided at the rear end of the main frame 31, and a seat 4a on which a rider sits, a seat 4b on which a passenger sits, a rear trunk 7b, etc. are provided on the seat rails.

[0016] The front end of a rear swing arm 34 extending in the fore-and-aft direction is rotatably attached to the pivot plate 33. The rear end of the rear swing arm 34 rotatably supports the rear wheel RW and also supports a rear wheel brake RB (rear wheel brake caliper). The rear swing arm 34 is configured to be swingable in the up-and-down direction by a rear suspension mechanism 11 provided between the rear swing arm 34 and the body frame 3 (main frame 31). The rear suspension mechanism 11 may be configured as an electronically controlled suspension capable of electronically controlling damping force. In addition, an exhaust muffler 6 that silences exhaust from the engine 21 is provided on either side of the rear wheel RW in the X direction. In addition, left and right saddlebags 7a are provided on either side of the rear wheel RW.

[0017] A front suspension mechanism 9 that supports a front wheel FW so that it can swing freely is configured at the front end of the main frame 31. The front suspension mechanism 9 can be configured as an electronically controlled suspension that can electronically control damping force. The front suspension mechanism 9 includes an upper link 91, a lower link 92, a fork support 93, a vibration reduction mechanism 94 (cushion unit), and a pair of left and right front forks 95. In the front suspension mechanism 9, the upper link 91, the lower link 92, the fork support 93, and the vibration reduction mechanism 94 form a support mechanism that supports the front forks 95 of the vehicle 1.

[0018] The upper link 91 and the lower link 92 are disposed above and below the front end of the main frame 31. The rear ends of the upper link 91 and the lower link 92 are pivotally connected to the front end of the main frame 31. The upper link 91 and the lower link 92 are pivotally connected to a fork support 93.

[0019] The fork support 93 is cylindrical and tilted backward. A steering shaft 96 is supported on the fork support 93 so as to be rotatable about its axis. The steering shaft 96 has a shaft portion (not shown) that passes through the fork support 93. A bridge (not shown) is provided at the lower end of the steering shaft 96, and a pair of left and right front forks 95 are supported on this bridge. The front forks 95 rotatably support a front wheel FW and also support a front wheel brake FB (front wheel brake caliper). The upper end of the steering shaft 96 is connected via a link 97 to a steering shaft (not shown) that is rotated by the handlebars 8. The upper part of the front wheel FW is covered with a fender 10, which is supported by the front forks 95.

[0020] 2 is a diagram showing an example of the configuration of a control system 100 (control device) according to this embodiment. The control system 100 is a system that controls the operation, behavior, etc. of the vehicle 1, and may include a sensor group 110, a control unit 121, and an acquisition unit 122. The control system 100 may also include a front wheel ABS device 131 that activates an anti-lock braking system (ABS) for the front wheel brakes FB, a rear wheel ABS device 132 that activates an ABS for the rear wheel brakes RB, and a traction control system (TCS) device 133 that activates a traction control system (TCS) for the rotational driving force of the rear wheels RW.

[0021] The sensor group 110 may include an inertial sensor 111 (first detection unit), a stroke sensor 112 (second detection unit), a front wheel speed sensor 113 (fourth detection unit), and a rear wheel speed sensor 114 (third detection unit).

[0022] The inertial sensor 111 includes an inertial measurement unit (IMU) that detects the acceleration and angular velocity occurring in the body of the vehicle 1 as the behavior (body state) of the vehicle 1. The inertial sensor 111 (inertial measurement unit) is disposed at any appropriate location on the vehicle 1 (body), for example, near the center of gravity of the vehicle 1. In this embodiment, the inertial sensor 111 detects the acceleration of the vehicle body in each of the X direction (front-rear direction of the vehicle), Y direction (vehicle width direction), and Z direction (vehicle up-down direction), and also detects the angular velocity of the vehicle body in each of the ωX direction, ωY direction, and ωZ direction. The ωX direction is the rotation direction around the X axis (roll direction), the ωY direction is the rotation direction around the Y axis (pitch direction), and the ωZ direction is the rotation direction around the Z axis (yaw direction). Here, the inertial sensor 111 in this embodiment is configured to detect and output the acceleration of the vehicle body, but it may also be configured to detect and output the velocity of the vehicle body, or to detect the acceleration of the vehicle body and output the velocity obtained by integrating the acceleration.

[0023] The stroke sensor 112 detects the stroke speed of the front suspension mechanism 9 (front wheels FW) as a change in the state of the front suspension mechanism 9. The stroke sensor 112 may be configured to detect the stroke displacement of the front suspension mechanism 9 (front wheels FW). In the vehicle 1 of this embodiment, the stroke sensor 112 is only provided in the front suspension mechanism 9, and no stroke sensor is provided in the rear suspension mechanism 11. This reduces vehicle costs. In addition, the front wheel speed sensor 113 detects the wheel speed (rotational speed) of the front wheels FW, and the rear wheel speed sensor 114 detects the wheel speed (rotational speed) of the rear wheels RW. Note that, hereinafter, the stroke speed of the front suspension mechanism 9 (front wheels FW) may be referred to as the "front stroke speed," and the stroke speed of the rear suspension mechanism 11 (rear wheels RW) may be referred to as the "rear stroke speed."

[0024] The control unit 121 controls each part of the vehicle 1 based on the detection results of the sensors 111 to 114. In this embodiment, the control unit 121 controls the front suspension mechanism 9, the rear suspension mechanism 11, the front wheel ABS device 131 (front wheel brake FB), the rear wheel ABS device 132 (rear wheel brake RB), the TCS device (power unit 2), and the meter unit MU (display) based on the detection results of the sensors 111 to 114. In addition, from the perspective of improving the steering stability and ride comfort of the vehicle 1, the control unit 121 performs so-called skyhook control, which controls (adjusts) the damping forces of the front suspension mechanism 9 and the rear suspension mechanism 11 using the skyhook theory, which assumes that the vehicle 1 (car body, etc.) is suspended in mid-air by a virtual line.

[0025] The control unit 121 may be configured, for example, by a computer including a processor such as a CPU, a storage device such as a semiconductor memory, an interface with external devices, etc. The control unit 121 may also be configured by an ECU (Electronic Control Unit) mounted on the vehicle 1. The storage device (memory) of the control unit 121 stores an application program (hereinafter sometimes referred to as a "control program") for controlling the vehicle 1 based on the detection results of the sensors 111 to 114, and the processor of the control unit 121 may read and execute the control program stored in the storage device. Here, the control program includes a program for estimating the force acting on the rear wheel RW (rear wheel ground load) based on the detection results of the inertia sensor 111 and the stroke sensor 112 and controlling the rear suspension mechanism 11 based on the estimated value. The control program may be stored in a storage medium such as a CD-ROM, DVD, or memory and installed in the control unit 121 from the storage medium, or may be downloaded from an external server via a network and installed in the control unit 121.

[0026] The acquisition unit 122 acquires various types of information. For example, the acquisition unit 122 may be configured as an input unit that accepts information input by a user (e.g., a driver) via an input / output device (e.g., a meter unit MU) of the vehicle 1. Examples of the input / output device include a group of switches and a touch panel display provided on the vehicle 1. Alternatively, the acquisition unit 122 may be configured as a communication unit that is communicably connected to a user's information terminal and acquires, from the information terminal, information input to the information terminal by the user.

[0027] 3 is a diagram showing a model of the front suspension mechanism 9 and the rear suspension mechanism 11 in this embodiment. The front suspension mechanism 9 and the rear suspension mechanism 11 are mechanisms for reducing vibrations transmitted from the road surface RS to the body BD of the vehicle 1. The front suspension mechanism 9 has an elastic member 9a and a viscous damping member 9b. Similarly, the rear suspension mechanism 11 has an elastic member 11a and a viscous damping member 11b.

[0028] The elastic members 9a and 11a have a spring constant. Springs, rubber, or the like may be used as the elastic members 9a and 11a, and in this embodiment, coil springs may be used. Furthermore, although not shown in detail, the viscous damping members 9b and 11b are monotube-type and may be configured using magnetorheological fluid (MRF) as the hydraulic fluid. A piston rod is axially slidably inserted into a cylindrical cylinder filled with MRF, and a piston attached to the tip of the piston rod divides the interior of the cylinder into an upper oil chamber and a lower oil chamber. When current is supplied to a coil located inside a communication passage connecting the upper and lower oil chambers, a magnetic field is applied to the MRF flowing through the communication passage, causing ferromagnetic particles to form clusters. This changes the viscosity of the MRF passing through the communication passage, thereby changing the damping force of the viscous damping members 9b and 11b. In other words, the control unit 121 can control (adjust) the damping force of the suspension mechanisms 9 and 11 by supplying current to the coils of the viscous damping members 9b and 11b and changing the viscosity of the magnetic fluid inside the viscous damping members 9b and 11b.

[0029] Here, the viscous damping members 9 b, 11 b are not limited to mechanisms using magnetorheological fluid (MRF), but may be mechanisms that adjust the damping force by varying the diameter of an orifice using a step motor or the like to change the amount of oil (hydraulic oil) passing through the orifice. In this case, the control unit 121 can change the diameter of the orifice of the viscous damping members 9 b, 11 b to change the amount of oil passing through the orifice, thereby controlling (adjusting) the damping force of the suspension mechanisms 9, 11.

[0030] In the control system 100, a stroke sensor 112 is provided in the front suspension mechanism 9, and the control unit 121 controls (adjusts) the damping force of the front suspension mechanism 9 based on the detection result (front stroke speed) of the stroke sensor 112. On the other hand, providing a stroke sensor in the rear suspension mechanism 11 would be disadvantageous in terms of vehicle cost. Therefore, the control unit 121 estimates the rear wheel ground load, which is the force acting on the rear wheel RW from the road surface RS (obstacle OB), based on the detection result of the stroke sensor 112 provided in the front suspension mechanism 9, and controls (adjusts) the damping force of the rear suspension mechanism 11 based on the estimated value. For example, the control unit 121 estimates the rear wheel ground load based on the front stroke speed detected by the stroke sensor 112, and calculates the rear stroke speed that may occur in the rear suspension mechanism 11 (rear wheel RW) based on the estimated value of the rear wheel ground load, thereby controlling the damping force of the rear suspension mechanism 11. A method for calculating the rear stroke speed based on the front stroke speed detected by the stroke sensor 112 will be described below.

[0031] [Method of Calculating Rear Stroke Speed] The front stroke speed Vpf generated in the front suspension mechanism 9 when the front wheel FW passes over the obstacle OB can be expressed by the following equation (1). "Vzf" in equation (1) represents the speed of the front part of the vehicle body BD in the vehicle up-down direction, and may be referred to as "front body speed Vzf" below. When the front suspension mechanism 9 is considered as a spring, the front body speed Vzf may be understood as the speed of the sprung mass. Furthermore, "Vzwf" in equation (1) represents the speed of the front wheel FW in the vehicle up-down direction, and may be referred to as "front wheel speed Vzwf" below. When the front suspension mechanism 9 is considered as a spring, the front wheel speed Vzwf may be understood as the speed of the unsprung mass. Vpf = Vzf - Vzwf (1)

[0032] The front vehicle body speed Vzf is expressed by the following equation (2). "Vz" in equation (2) represents the vehicle vertical speed of the vehicle body BD when the front wheels FW are affected by the obstacle OB, and can be obtained from the detection result of the inertial sensor 111. In this embodiment, the inertial sensor 111 is configured to detect the vehicle vertical acceleration Gz that occurs at a representative position of the vehicle body BD. Therefore, the speed Vz can be obtained by integrating the acceleration Gz detected by the inertial sensor 111. "Lf" in equation (2) represents the distance (first distance) between the front suspension mechanism 9 and the representative position of the vehicle body BD in the vehicle longitudinal direction. The distance Lf can be the horizontal distance between the axle position of the front wheels (front wheels FW) and the representative position of the vehicle body BD. The distance Lf is a known value. Furthermore, "ωy" in equation (2) represents the angular velocity in the pitch direction (ωy direction) detected by the inertial sensor 111 when the front wheels FW are affected by the obstacle OB. The representative position of the vehicle body BD may be, for example, the position of the vehicle body BD where the acceleration and angular velocity are detected by the inertial sensor 111 (i.e., the position that serves as the measurement reference). The representative position of the vehicle body BD may also be the position of the center of gravity of the vehicle 1 (vehicle body BD) in the vehicle longitudinal direction. Vzf=Vz-Lf*ωy (2)

[0033] Here, speed and acceleration are highly related parameters that can be converted by differentiation / integration. Therefore, the inertial sensor 111 of this embodiment may be understood as detecting the speed Vz of the vehicle body BD in the vertical direction of the vehicle. Alternatively, the inertial sensor 111 may be configured to include a speed sensor that detects the speed Vz of the vehicle body BC, or may be configured to detect the acceleration Gz of the vehicle body BD, integrate the acceleration Gz, and output the speed Vz.

[0034] The front wheel speed Vzwf is expressed by the following equation (3). "Fzf" in equation (3) represents the first force acting on the front wheel FW from the obstacle OB, and may be referred to as "front wheel ground load Fzf" below. Furthermore, "Mf" in equation (3) represents the front unsprung mass (specifically, the mass or weight including the front wheel FW (front wheel) as well as a part of the front suspension mechanism 9). The mass Mf of the front wheel FW is a known value. The front wheel speed Vzwf is calculated by integrating the value obtained by dividing the front wheel ground load Fzf by the mass Mf of the front wheel FW. Vzwf = ∫Fzf / Mfdt (3)

[0035] By substituting equations (2) and (3) into equation (1), the following equation (4) is obtained. In equation (4), the front stroke speed Vpf is obtained from the detection result of the stroke sensor 112, and the speed Vz and angular speed ωy are obtained from the detection result of the inertial sensor 111. In addition, the distance Lf and the mass Mf are known values. Therefore, the front wheel ground load Fzf can be calculated using equation (4). Vpf = (Vz - Lf * ωy) - (∫Fzf / Mfdt) ... (4)

[0036] Next, a second force estimated to act on the rear wheel RW from the obstacle OB is calculated based on the front wheel ground load Fzf. Hereinafter, the second force may be referred to as the "rear wheel ground load Fzr." In the vehicle 1, the ground load received from the obstacle OB may differ between the front wheels FW and the rear wheels RW depending on the state of the vehicle 1, such as the bank angle (roll angle) and acceleration. In this case, simply using the front wheel ground load Fzf as the rear wheel ground load Fzr makes it difficult to accurately control (adjust) the damping force of the rear suspension mechanism 11, which may result in a decrease in the handling stability and ride comfort of the vehicle 1. Therefore, the control unit 121 of this embodiment obtains the difference between the state of the vehicle 1 when the front wheels FW are affected by the obstacle OB and when the rear wheels RW are affected by the obstacle OB, and estimates a force converted from the front wheel ground load Fzf as the rear wheel ground load Fzr based on this difference. In this embodiment, the bank angle (roll angle) of the vehicle 1 is used as an example of the state of the vehicle 1. The obstacle OB may be a convex or concave portion occurring on the road surface RS itself, such as an unevenness of the road surface RS, or may be an object placed or installed on the road surface RS.

[0037] Specifically, as shown in FIG. 4A , a reference force vector Fz is calculated based on the front wheel ground contact load Fzf. The reference force vector Fz represents a force in a reference direction, and in this embodiment, may be set as a force in the vertical direction. The reference force vector Fz may be expressed by equation (5) based on the front wheel ground contact load Fzf. "φ1" in equation (5) represents the roll angle of the vehicle 1 when the front wheel FW is affected by the obstacle OB, i.e., the roll angle of the front wheel FW, and may be obtained by integrating the angular velocity in the roll direction (ωx direction) detected by the inertial sensor 111. Note that the vehicle 1 may be provided with a bank angle sensor that detects the bank angle of the vehicle 1. In this case, the bank angle (roll angle) detected by the bank angle sensor may be applied to "φ1" in equation (5). Fz=Fzf / cos(φ1) (5)

[0038] On the other hand, the rear wheel ground load Fzr estimated to act on the rear wheel RW from the obstacle OB is calculated based on the reference force vector Fz calculated by equation (5), as shown in FIG. 4B . That is, the rear wheel ground load Fzr is calculated by equation (6) on the assumption that the reference force vector Fz is the same when the front wheel FW is affected by the obstacle OB and when the rear wheel RW is affected by the obstacle OB. "φ2" in equation (6) represents the bank angle of the vehicle 1 when the rear wheel RW is affected by the obstacle OB, i.e., the roll angle of the rear wheel RW, and can be obtained by integrating the angular velocity in the roll direction (ωx direction) detected by the inertial sensor 111. The vehicle 1 may be provided with a bank angle sensor that detects the bank angle of the vehicle 1. In this case, the bank angle (roll angle) detected by the bank angle sensor can be applied to "φ2" in equation (6). Fzr = Fz × cos(φ2) (6)

[0039] Next, we will determine the rear stroke speed Vpr that is estimated to occur in the rear suspension mechanism 11 when the rear wheel RW is affected by the obstacle OB. The rear stroke speed Vpr can be calculated using the following equation (7). "Vzr" in equation (7) represents the speed of the rear part of the vehicle body BD in the vehicle up-down direction, and may be referred to as "rear body speed Vzr" below. When the rear suspension mechanism 11 is considered as a spring, the rear body speed Vzr may be understood as the speed of the sprung mass. Furthermore, "Vzwr" in equation (7) represents the speed of the rear wheel RW in the vehicle up-down direction, and may be referred to as "rear wheel speed Vzwr" below. When the rear suspension mechanism 11 is considered as a spring, the rear wheel speed Vzwr may be understood as the speed of the unsprung mass. Vpr = Vzr - Vzwr (7)

[0040] The rear vehicle body speed Vzr is expressed by the following equation (8). "Vz" in equation (8) represents the vehicle vertical speed of the vehicle body BD when the rear wheel RW is affected by the obstacle OB, and can be obtained from the detection result of the inertial sensor 111. In this embodiment, the inertial sensor 111 is configured to detect the vehicle vertical acceleration Gz that occurs at a representative position of the vehicle body BD. Therefore, the speed Vz can be obtained by integrating the acceleration Gz detected by the inertial sensor 111. "Lr" in equation (8) represents the distance (second distance) between the rear suspension mechanism 11 and the representative position of the vehicle body BD in the vehicle longitudinal direction. The distance Lr can be the horizontal distance between the axle position of the rear wheel (rear wheel RW) and the representative position of the vehicle body BD. The distance Lr is a known value. Furthermore, "ωy" in equation (8) represents the angular velocity in the pitch direction (ωy direction) detected by the inertial sensor 111 when the rear wheel RW is affected by the obstacle OB. Note that the representative position of the vehicle body BD is as described above. Vzr=Vz+Lr*ωy (8)

[0041] The rear wheel speed Vzwr is expressed by the following equation (9). "Fzr" in equation (9) represents the rear wheel ground load (estimated value) estimated to act on the rear wheel RW from the obstacle OB, and is the value obtained by the above equation (6). Also, "Mr" in equation (9) represents the rear wheel unsprung mass (specifically, the mass or weight including the rear wheel RW (rear wheel) as well as a part of the rear suspension mechanism 11). The mass Mr of the rear wheel RW is a known value. The rear wheel speed Vzwr is calculated by integrating the value obtained by dividing the rear wheel ground load Fzr by the mass Mr of the rear wheel RW. Vzwr = ∫Fzr / Mrdt (9)

[0042] By substituting equations (8) and (9) into equation (7), the following equation (10) is obtained. In equation (10), the velocity Vz and angular velocity ωy are obtained from the detection results of the inertial sensor 111. The distance Lr and mass Mr are known values. The rear wheel ground load Fzr is calculated using equation (6) above. Therefore, the rear stroke velocity Vpr can be estimated (calculated) using equation (10). This allows the control unit 121 to control (adjust) the damping force of the rear suspension mechanism 11 based on the estimated rear stroke velocity Vpr. Vpr = (Vz + Lr * ωy) - (∫Fzr / Mrdt) ... (10)

[0043] [Control of Each Suspension Mechanism] First, a method for controlling the front suspension mechanism 9 will be described. Fig. 5 is a flowchart showing the method for controlling the front suspension mechanism 9. The flowchart in Fig. 5 can be executed by the control unit 121. Note that the flowchart in Fig. 5 can be executed repeatedly. That is, after step S11 is completed, the process starts again from step S10.

[0044] As described above, the front suspension mechanism 9 is provided with a stroke sensor 112. Therefore, control of the front suspension mechanism 9 can be achieved by a simple flow of steps S101 to S102. In step S101, the control unit 121 acquires the front stroke speed Vpf based on the detection result of the stroke sensor 112. Next, in step S102, the control unit 121 determines a control current value based on the front stroke speed Vpf acquired in step S101, and controls (adjusts) the damping force of the front suspension mechanism 9 using this control current value. The control current value can be the current value to be supplied to the coil or step motor of the viscous damping member 9b in the front suspension mechanism 9. Step S102 will be described in detail later.

[0045] Next, a method for controlling the rear suspension mechanism 11 will be described. Fig. 6 is a flowchart showing the method for controlling the rear suspension mechanism 11. The flowchart in Fig. 6 can be executed by the control unit 121 in parallel with the flowchart in Fig. 5. The flowchart in Fig. 6 can be executed repeatedly. That is, after step S210 is completed, the process starts again from step S201.

[0046] Steps S201 to S204 are steps for determining the front wheel ground load Fzf and the reference force vector Fz.

[0047] In step S201, the control unit 121 acquires the front stroke speed Vpf based on the detection result of the stroke sensor 112. In step S202, the control unit 121 acquires the roll angle φ1 of the front wheels FW based on the calculation result using information from the inertial sensor 111. Next, in step S203, the control unit 121 acquires the acceleration Gz in the vehicle vertical direction and the angular velocity ωy in the pitch direction of the vehicle body BD (representative position) based on the detection result of the inertial sensor 111. The acceleration Gz acquired in step S203 is converted into a velocity Vz by integration. Here, the control unit 121 may perform high-pass filtering on each piece of information acquired in steps S201 to S203 to remove vibration components (low-frequency components) caused by the movement of the vehicle body BD and the engine 21.

[0048] In step S204, the control unit 121 calculates the front wheel ground contact load Fzf using the above equation (4) based on the front stroke speed Vpf acquired in step S201 and the speed Vz and angular speed ωy acquired in step S203. Next, in step S205, the control unit 121 calculates the reference force vector Fz using the above equation (5) based on the roll angle φ1 acquired in step S202 and the front wheel ground contact load Fzf obtained in step S204.

[0049] Steps S206 to S209 are steps for estimating the rear wheel ground load Fzr and estimating the rear stroke speed Vpr based on the estimated value.

[0050] In step S206, the control unit 121 acquires the roll angle φ2 of the rear wheels RW based on the calculation results using the information from the inertial sensor 111. Next, in step S207, the control unit 121 acquires the acceleration Gz in the vehicle's vertical direction and the angular velocity ωy in the pitch direction at the vehicle body BD (representative position) based on the detection results of the inertial sensor 111. The acceleration Gz acquired in step S207 is converted into a velocity Vz by integration. Here, the control unit 121 may perform high-pass filtering on each piece of information acquired in steps S206 to S207 to remove vibration components (low-frequency components) caused by the movement of the vehicle body BD and the engine 21.

[0051] In step S208, the control unit 121 calculates the rear wheel ground load Fzr using the above equation (6) based on the reference force vector Fz obtained in step S205 and the roll angle φ2 of the rear wheel RW obtained in step S206. Next, in step S209, the control unit 121 estimates (calculates) the rear stroke speed Vpr using the above equation (10) based on the speed Vz and angular speed ωy obtained in step S207 and the rear wheel ground load Fzr obtained in step S208. Note that in step S209, the acceleration Gz (speed Vz) and angular speed ωy obtained in step S203 may be used. In this case, step S207 may be omitted.

[0052] In step S210, the control unit 121 determines a control current value based on the rear stroke speed Vpr estimated in step S209, and controls (adjusts) the damping force of the rear suspension mechanism 11 using the determined control current value. The control current value may be a current value to be supplied to the coil or step motor of the viscous damping member 11b in the rear suspension mechanism 11. Step S210 will be described in detail later.

[0053] Here, the control of the damping force of the rear suspension mechanism 11 in step S210 may be performed at a timing obtained by adding a delay time (e.g., WB × Vx) determined by the wheelbase WB and the vehicle speed Vx to the timing of obtaining the front stroke speed Vpf in step S201 or the timing of controlling the damping force of the front suspension mechanism 9 in step S102. The wheelbase WB is the distance between the axle positions of the front wheels (FW) and the axle positions of the rear wheels (RW) in the longitudinal direction of the vehicle, and is known information. The vehicle speed Vx is the speed of the vehicle 1 in the longitudinal direction of the vehicle, and may be obtained based on the acceleration in the longitudinal direction of the vehicle detected by the inertial sensor 111, or may be obtained based on the detection results of the front wheel speed sensor 113 or the rear wheel speed sensor 114. Alternatively, if a vehicle speed sensor is provided in the vehicle 1, the vehicle speed Vx may be detected by the vehicle speed sensor.

[0054] [Method for Determining Control Current Values] Next, a method for determining control current values ​​for controlling the damping forces of the suspension mechanisms 9, 11 in steps S102 and S210 will be described. Fig. 7 is a flowchart showing the method for determining control current values. The flowchart in Fig. 7 can be executed by the control unit 121.

[0055] In step S301, the control unit 121 calculates the critical damping coefficient Cc. The critical damping coefficient Cc is a coefficient used to determine the critical state (i.e., the limit value of the damping force) of whether or not vibration occurs in the mass Mr of the rear wheel RW. It is determined by the equation "Cc = 2√(m·k)." In this equation, "m" represents the sprung mass, and the mass M*(Lr / WB) of the front axle or the mass M*(Lf / WB) of the rear axle may be input. Furthermore, "k" represents the wheel rate, and the spring constant of the elastic member 9a of the front suspension mechanism 9 or the spring constant of the elastic member 11a of the rear suspension mechanism 11 may be input. Since the unsprung mass m and the wheel rate k are known values, the critical damping coefficient Cc is also known. Therefore, step S301 need not be performed sequentially; a previously calculated critical damping coefficient Cc may be stored in a storage device of the control unit 121. In this case, step S301 may be omitted.

[0056] In step S302, the control unit 121 determines a gain (hereinafter sometimes referred to as a "Vz gain") for amplifying the damping force in accordance with the vehicle body speed Vz. For example, the control unit 121 uses the Vz gain map shown in FIG. 8 when determining the Vz gain. The Vz gain map is information indicating the relationship between the vehicle body speed Vz (horizontal axis) and the Vz gain (vertical axis), and can be generated in advance. The Vz gain map may be generated commonly for the front suspension mechanism 9 and the rear suspension mechanism 11, or may be generated separately.

[0057] When determining the control current value for the front suspension mechanism 9, the control unit 121 inputs the front vehicle body speed Vzf obtained by the above equation (2) as the vehicle body speed Vz on the horizontal axis in the Vz gain map. This makes it possible to determine the Vz gain corresponding to the front vehicle body speed Vzf. On the other hand, when determining the control current value for the rear suspension mechanism 11, the control unit 121 inputs the rear vehicle body speed Vzr obtained by the above equation (8) as the vehicle body speed Vz on the horizontal axis in the Vz gain map. This makes it possible to determine the Vz gain corresponding to the rear vehicle body speed Vzr.

[0058] In step S303, the control unit 121 determines the extension / retraction of the front and rear suspensions based on the front stroke speed detected by the stroke sensor 112 and the vertical direction of the estimated rear stroke speed Vpr calculated based on the rear wheel ground contact load. If a stroke sensor is attached to the rear wheel, the extension / retraction of the rear suspension may be determined based on the rear stroke speed.

[0059] In step S304, the control unit 121 inputs gains to the front and rear suspensions according to the extension / compression determined in step S303, thereby performing control so that the damping force is appropriate for the vehicle characteristics. Different gains may be input depending on the extension and compression of the suspension. For example, a larger gain may be input when the suspension is extending compared to when it is compressing. Alternatively, different gains may be input for extension and compression of the front suspension, and the same gain may be input for extension and compression of the rear suspension. Hereinafter, the gains input here will be referred to as suspension extension / compression gains.

[0060] In step S305, the control unit 121 determines the required damping force of the suspension mechanism. The required damping force is the damping force required for the suspension mechanism in skyhook control. For example, the control unit 121 uses the damping force map shown in FIG. 9 to determine the required damping force. The damping force map is information indicating the relationship between stroke speed (horizontal axis) and required damping force (vertical axis), and can be generated in advance. The damping force maps can be generated separately for the front suspension mechanism 9 and the rear suspension mechanism 11.

[0061] When determining the control current value for the front suspension mechanism 9, the control unit 121 inputs the front stroke speed Vpf obtained in step S101 as the stroke speed on the horizontal axis in the damping force map. This allows the required damping force corresponding to the front stroke speed Vpf to be determined. On the other hand, when determining the control current value for the rear suspension mechanism 11, the control unit 121 inputs the rear stroke speed Vpr obtained in step S209 as the stroke speed on the horizontal axis in the damping force map. This allows the required damping force corresponding to the rear stroke speed Vpr to be determined.

[0062] In step S306, the control unit 121 corrects the required damping force determined in step S305 using the critical damping coefficient Cc determined in step S301 and the Vz gain determined in step S302. For example, the control unit 121 corrects the required damping force by multiplying the required damping force by the critical damping coefficient Cc and the Vz gain. Hereinafter, the required damping force corrected by the critical damping coefficient Cc, the Vz gain, and the suspension extension / compression gain may be referred to as the "corrected damping force."

[0063] In step S307, the control unit 121 determines a provisional value of the control current value (hereinafter, sometimes referred to as the "provisional current value"). For example, the control unit 121 determines the provisional current value using the provisional current value map shown in FIG. 10. The provisional current value map is information indicating the relationship between the corrected damping force (horizontal axis) and the provisional current value (vertical axis), and can be generated in advance for each stroke speed. FIG. 10 shows an example in which provisional current value maps generated for each of stroke speeds V1 to V5 are overlapped. The provisional current value map may be generated commonly for the front suspension mechanism 9 and the rear suspension mechanism 11, or may be generated separately.

[0064] When determining the control current value for the front suspension mechanism 9, the control unit 121 selects a provisional current value map corresponding to the front stroke speed Vpf obtained in step S101 and inputs the corrected damping force determined for the front suspension mechanism 9 in step S306 as the corrected damping force on the horizontal axis of the selected provisional current value map. This makes it possible to determine the provisional current value for the front suspension mechanism 9 corresponding to the corrected damping force. On the other hand, when determining the control current value for the rear suspension mechanism 11, the control unit 121 selects a provisional current value map corresponding to the rear stroke speed Vpr obtained in step S209 and inputs the corrected damping force determined for the rear suspension mechanism 11 in step S306 as the corrected damping force on the horizontal axis of the selected provisional current value map. This makes it possible to determine the provisional current value for the rear suspension mechanism 11 corresponding to the corrected damping force.

[0065] In step S308, the control unit 121 determines the control current value by correcting the provisional current value determined in step S307. For example, the control unit 121 uses the limit current value map shown in FIG. 11 to correct the provisional current value. The limit current value map is information indicating the relationship between stroke speed (horizontal axis) and limit current value (vertical axis), and can be generated in advance. The limit current value is the limit value of the current supplied to the coil of the viscous damping member of the suspension mechanism or the step motor. The limit current value map may be generated commonly for the front suspension mechanism 9 and the rear suspension mechanism 11, or may be generated separately.

[0066] When determining the control current value for the front suspension mechanism 9, the control unit 121 inputs the front stroke speed Vpf obtained in step S101 as the stroke speed on the horizontal axis in the limit current value map and calculates the limit current value corresponding to the front stroke speed Vpf. If the provisional current value determined in step S307 is equal to or less than the limit current value, the control unit 121 determines the provisional current value as the control current value. If the provisional current value determined in step S307 is greater than the limit current value, the control unit 121 determines the limit current value as the control current value. On the other hand, when determining the control current value for the rear suspension mechanism 11, the control unit 121 inputs the rear stroke speed Vpr obtained in step S209 as the stroke speed on the horizontal axis in the limit current value map and calculates the limit current value corresponding to the rear stroke speed Vpf. Then, if the provisional current value determined in step S307 is less than or equal to the limit current value, the control unit 121 determines the provisional current value as the control current value, and if the provisional current value determined in step S307 is greater than the limit current value, the control unit 121 determines the limit current value as the control current value.

[0067] As described above, the control system 100 of this embodiment is provided with the inertial sensor 111, which detects the vehicle vertical velocity Vz and the pitch angular velocity ωy of the vehicle body BD, and the stroke sensor 112, which detects the front stroke velocity Vpf of the front suspension mechanism 9. The control unit 121 estimates the rear wheel ground load Fzr based on the detection results of the inertial sensor 111 and the stroke sensor 112, and controls the vehicle 1 based on the estimated value. Specifically, the control unit 121 controls the damping force of the rear suspension mechanism 11 based on the estimated value of the rear wheel ground load Fzr. This allows the damping force of the rear suspension mechanism 11 to be controlled accurately and in real time without providing a stroke sensor in the rear suspension mechanism 11. This is advantageous in terms of vehicle cost and improves the behavioral stability and ride comfort of the saddle-ride type vehicle 1.

[0068] Second Embodiment A second embodiment of the present invention will be described. In this embodiment, an example will be described in which rear stroke speed Vpr is corrected based on the weight distribution of occupants and / or cargo in vehicle 1. This embodiment basically follows on from the first embodiment, and can follow the first embodiment except for the matters mentioned below.

[0069] In the vehicle 1, if a passenger is seated on the rear seat 4b or if luggage is loaded in the saddlebags 7a or rear trunk 7b, the weight balance of the vehicle 1 may change accordingly. That is, the weight balance of the vehicle 1 may change depending on the weight distribution of the occupants and / or cargo in the vehicle 1. Changes in the weight balance of the vehicle 1 may particularly affect the control of the rear suspension mechanism 11 and may cause a decrease in the vehicle's stability and ride comfort. Therefore, the control system 100 of this embodiment acquires information indicating the weight distribution of the occupants and / or cargo in the vehicle 1, and corrects the rear stroke speed Vpr estimated in step S209 above as the stroke speed to be generated in the rear suspension mechanism 11 based on this information. Note that, hereinafter, information indicating the weight distribution of the occupants and / or cargo in the vehicle 1 may be referred to as "weight distribution information."

[0070] Figure 12 is a flowchart showing a method for correcting rear stroke speed Vpr. The flowchart of Figure 12 can be executed by control unit 121. The flowchart of Figure 12 can be executed repeatedly. That is, after step S403 is completed, the process starts again from step S401.

[0071] In step S401, the control unit 121 acquires weight distribution information via the acquisition unit 122. For example, the weight distribution information may include the number of occupants on the vehicle 1, whether or not there is cargo in the saddlebags 7a, and / or whether or not there is cargo in the rear trunk 7b. Alternatively, the weight distribution information may include the weight of the driver and passengers riding in the vehicle 1, the weight of cargo in the saddlebags 7a, the weight of cargo in the rear trunk 7b, etc. The acquisition unit 122 may acquire weight distribution information input by the user via an input / output device (e.g., the meter unit MU) of the vehicle 1, or may acquire weight distribution information input by the user to an information terminal from the information terminal.

[0072] In step S402, the control unit 121 determines a correction value for correcting the rear stroke speed Vpr (hereinafter sometimes referred to as the "rear stroke correction value") based on the weight distribution information acquired in step S401. For example, the control unit 121 can determine the rear stroke correction value according to the weight distribution information based on information generated in advance that indicates the relationship between the weight distribution of the vehicle 1 and the rear stroke correction value. Furthermore, if the weight distribution information is determined by the presence or absence of a passenger and / or cargo in the vehicle 1, the control unit 121 can determine the rear stroke correction value according to the weight distribution information based on information generated in advance that indicates the relationship between the presence or absence of a passenger and / or cargo and the rear stroke correction value.

[0073] In step S403, the control unit 121 corrects the rear stroke speed Vpr using the rear stroke correction value determined in step S402. The rear stroke correction value may be in the form of a coefficient or an addition (subtraction) value. For example, the rear stroke correction value may be applied to the distance Lf in the above equation (2) and the distance Lr in the above equation (8), or may be applied to the rear stroke speed Vpr itself obtained in step S209.

[0074] As described above, in this embodiment, the rear stroke speed Vpr is corrected based on the weight distribution information. This allows the rear suspension mechanism 11 to be accurately controlled in accordance with changes in the weight distribution of occupants and / or cargo in the vehicle 1. In other words, it is possible to suppress deterioration in the behavioral stability and ride comfort of the vehicle 1 due to changes in the weight distribution.

[0075] Third Embodiment A third embodiment of the present invention will be described. In this embodiment, an example will be described in which the front wheel ABS device 131 is controlled in accordance with the front wheel ground load Fzf (estimated value), and the rear wheel ABS device 132 is controlled in accordance with the rear wheel ground load Fzr (estimated value). Note that this embodiment basically inherits the first embodiment, and can follow the first embodiment except for the matters mentioned below. Furthermore, the second embodiment may also be applied to this embodiment.

[0076] The front wheel ABS device 131 is a device that activates the ABS for the front wheel brake FB by reducing the hydraulic pressure of the front wheel brake FB when predetermined activation conditions are met. The ABS activation conditions for the front wheel ABS device 131 may include a condition that the deceleration of the wheel speed of the front wheel FW detected by the front wheel speed sensor 113 is equal to or greater than a front wheel deceleration threshold Awf. The rear wheel ABS device 132 is a device that activates the ABS for the rear wheel brake RB by reducing the hydraulic pressure of the rear wheel brake RB when predetermined activation conditions are met. The ABS activation conditions for the rear wheel ABS device 132 may include a condition that the deceleration of the wheel speed of the rear wheel RW detected by the rear wheel speed sensor 114 is equal to or greater than a rear wheel deceleration threshold (first threshold) Awr.

[0077] Here, in the vehicle 1, when the ground loads of each wheel (front wheel ground load Fzf, rear wheel ground load Fzr) are relatively small, the grip force between each wheel and the road surface RS is small, and therefore increasing the braking force may result in slippage or the like. On the other hand, when the ground loads of each wheel are relatively large, the grip force between each wheel and the road surface RS is large, and therefore increasing the braking force may result in little slippage or the like. Therefore, in this embodiment, the wheel speed deceleration thresholds (front wheel deceleration threshold Awf, rear wheel deceleration threshold Awr) at which the ABS is activated (intervenes) are changed according to the ground loads of each wheel. This allows the ABS to be activated appropriately so as to achieve both reduced slippage and reduced braking distance.

[0078] FIG. 13A is a flowchart showing a control method for the front wheel ABS device 131. FIG. 13B is a flowchart showing a control method for the rear wheel ABS device 132. The flowcharts of FIG. 13A and FIG. 13B can be executed in parallel by the control unit 121. Note that the flowcharts of FIG. 13A and FIG. 13B can be executed repeatedly. That is, in the flowchart of FIG. 13A, once step S515 is completed, the process starts again from step S511. Similarly, in the flowchart of FIG. 13B, once step S525 is completed, the process starts again from step S521.

[0079] First, the control of the front wheel ABS device 131 will be described with reference to FIG. 13A . In step S511, the control unit 121 acquires the front wheel ground load Fzf (estimated value). The front wheel ground load Fzf can be estimated (calculated) using the above-described equation (4). Next, in step S512, the control unit 121 determines the front wheel deceleration threshold Awf in accordance with the front wheel ground load Fzf acquired in step S511. For example, the control unit 121 can determine the front wheel deceleration threshold Awf in accordance with the front wheel ground load Fzf based on information generated in advance that indicates the relationship between the front wheel ground load Fzf and the front wheel deceleration threshold Awf. FIG. 14 shows an example of information indicating the relationship between the ground load and the deceleration threshold. When controlling the front wheel ABS device 131, the horizontal axis of FIG. 14 represents the front wheel ground load Fzf, and the vertical axis represents the front wheel deceleration threshold Awf. This allows the control unit 121 to determine the front wheel deceleration threshold Awf in accordance with the front wheel ground load Fzf so that the front wheel deceleration threshold Awf increases as the front wheel ground load Fzf increases.

[0080] In step S513, the control unit 121 determines the deceleration of the wheel speed of the front wheels FW using the front wheel speed sensor 113. Next, in step S514, the control unit 121 determines whether the deceleration determined in step S513 is equal to or greater than the front wheel deceleration threshold Awf. If the deceleration is less than the front wheel deceleration threshold Awf, the process returns to step S511. On the other hand, if the deceleration is equal to or greater than the front wheel deceleration threshold Awf, the process proceeds to step S515, where the control unit 121 activates the ABS for the front wheel brake FB by the front wheel ABS device 131.

[0081] Next, the control of the rear wheel ABS device 132 will be described with reference to FIG. 13B . In step S521, the control unit 121 acquires the rear wheel ground load Fzr (estimated value). The rear wheel ground load Fzf can be estimated (calculated) using the above-described equation (6). Next, in step S522, the control unit 121 determines the rear wheel deceleration threshold Awr in accordance with the rear wheel ground load Fzr acquired in step S521. For example, the control unit 121 can determine the rear wheel deceleration threshold Awr in accordance with the rear wheel ground load Fzr based on information indicating the relationship between the rear wheel ground load Fzr and the rear wheel deceleration threshold Awr that has been generated in advance. When controlling the rear wheel ABS device 132, the horizontal axis of FIG. 14 represents the rear wheel ground load Fzr, and the vertical axis represents the rear wheel deceleration threshold Awr. This allows the control unit 121 to determine the rear wheel deceleration threshold Awr in accordance with the rear wheel ground load Fzr such that the larger the rear wheel ground load Fzr, the larger the rear wheel deceleration threshold Awr.

[0082] In step S523, the control unit 121 determines the deceleration of the wheel speed of the rear wheel RW using the rear wheel speed sensor 114. Next, in step S524, the control unit 121 determines whether the deceleration determined in step S523 is equal to or greater than the rear wheel deceleration threshold Awr. If the deceleration is less than the rear wheel deceleration threshold Awr, the process returns to step S521. On the other hand, if the deceleration is equal to or greater than the rear wheel deceleration threshold Awr, the process proceeds to step S525, where the control unit 121 activates the ABS for the rear wheel brake RB using the rear wheel ABS device 132.

[0083] As described above, in this embodiment, the deceleration thresholds (front wheel deceleration threshold Awf, rear wheel deceleration threshold Awr) for activating the ABS are changed according to the ground contact load of each wheel, thereby enabling the ABS to be appropriately activated so as to achieve both reduced slippage and reduced braking distance.

[0084] <Fourth Embodiment> A fourth embodiment of the present invention will be described. In this embodiment, an example will be described in which the TCS device 133 is controlled in accordance with the rear wheel ground load Fzr (estimated value). Note that this embodiment basically inherits the first embodiment and can follow the first embodiment except for the matters mentioned below. Furthermore, this embodiment may also apply the second embodiment and / or the third embodiment.

[0085] The TCS device 133 is a device that activates the TCS with respect to the rotational driving force of the rear wheels RW by reducing the output of the power unit 2 (e.g., the engine 21) when a predetermined activation condition is satisfied. The activation condition of the TCS in the TCS device 133 may include a condition that the ratio of the wheel speed of the rear wheels RW to the wheel speed of the front wheels FW is equal to or greater than a ratio threshold value (second threshold value) St. The wheel speed of the front wheels FW is detected by a front wheel speed sensor 113, and the wheel speed of the rear wheels RW is detected by a rear wheel speed sensor 114.

[0086] Here, in the vehicle 1, the rear wheels RW can be drive wheels. In the vehicle 1, when the rear wheel ground load Fzr is relatively small, the grip force (friction force) between the rear wheels RW and the road surface RS is small, which may result in the rear wheels RW spinning. On the other hand, when the rear wheel ground load Fzr is relatively large, the grip force between the rear wheels RW and the road surface RS is large, which may result in the rear wheels RW spinning less. Therefore, in this embodiment, the ratio threshold St for activating (intervening) the TCS is changed according to the rear wheel ground load Fzr. This allows the TCS to be appropriately activated so as to reduce the rear wheels RW spinning.

[0087] Fig. 15 is a flowchart showing a method for controlling the TCS device 133. The flowchart in Fig. 15 can be executed by the control unit 121. The flowchart in Fig. 15 can be executed repeatedly. That is, after step S605 is completed, the process starts again from step S601.

[0088] In step S601, the control unit 121 acquires the rear wheel ground load Fzr (estimated value). The rear wheel ground load Fzr can be estimated (calculated) using the above-described equation (6). Next, in step S602, the control unit 121 determines the ratio threshold St according to the rear wheel ground load Fzr acquired in step S601. For example, the control unit 121 can determine the ratio threshold St according to the rear wheel ground load Fzr based on information indicating the relationship between the rear wheel ground load Fzr and the ratio threshold St that has been generated in advance. FIG. 16 shows an example of the information indicating the relationship between the rear wheel ground load Fzr and the ratio threshold St. This allows the control unit 121 to determine the ratio threshold St according to the rear wheel ground load Fzr such that the larger the rear wheel ground load Fzr, the larger the ratio threshold St.

[0089] In step S603, the control unit 121 calculates the ratio of the wheel speed of the rear wheels RW to the wheel speed of the front wheels FW (hereinafter, sometimes simply referred to as "ratio"). The control unit 121 can calculate the ratio by obtaining the wheel speed of the front wheels FW using the front wheel speed sensor 113 and obtaining the wheel speed of the rear wheels RW using the rear wheel speed sensor 114. Next, in step S604, the control unit 121 determines whether the ratio calculated in step S603 is equal to or greater than the ratio threshold value St. If the ratio is less than the ratio threshold value St, the process returns to step S601. On the other hand, if the ratio is equal to or greater than the ratio threshold value St, the process proceeds to step S605, where the control unit 121 activates the TCS using the TCS device 133.

[0090] As described above, in this embodiment, the ratio threshold St for activating the TCS is changed in accordance with the rear wheel ground load Fzr, thereby enabling the TCS to be appropriately activated so as to reduce spin of the rear wheels RW, which are the drive wheels.

[0091] Fifth Embodiment A fifth embodiment of the present invention will be described. In this embodiment, an example will be described in which a front wheel friction circle determined based on a front wheel ground load Fzf (estimated value) and a rear wheel friction circle determined from a rear wheel ground load Fzr (estimated value) are displayed. Note that this embodiment basically inherits the first embodiment and can follow the first embodiment except for the matters mentioned below. Furthermore, this embodiment may also apply the second, third, and / or fourth embodiments.

[0092] The friction circle is a conceptual diagram showing the magnitude of the grip force of a wheel (tire). The up, down, left, and right of the friction circle correspond to "deceleration," "acceleration," "left turn," and "right turn," respectively, and the grip force of the wheel is expressed as a vector representing each component of "deceleration," "acceleration," "left turn," and "right turn." The outer periphery of the friction circle represents the limit of the grip force of the wheel, and the size of the outer periphery of the friction circle changes depending on the ground load of the wheel. In this embodiment, the friction circle determined based on the estimated ground load is displayed on the display of the vehicle 1. This allows the driver to perform the intended vehicle operation (driving / braking, etc.) while checking the grip force of the wheel using the friction circle. Here, an example of the display of the vehicle 1 on which the friction circle is displayed is the display of the meter unit MU.

[0093] Fig. 17 is a flowchart showing a method for displaying a friction circle. The flowchart in Fig. 17 can be executed by the control unit 121. The flowchart in Fig. 17 can be executed repeatedly. That is, after step S705 is completed, the process starts again from step S701.

[0094] In step S701, the control unit 121 acquires the front wheel ground load Fzf (estimated value) and the rear wheel ground load Fzr (estimated value). The front wheel ground load Fzf can be estimated (calculated) using the above equation (4), and the rear wheel ground load Fzr can be estimated (calculated) using the above equation (6). Next, in step S702, the control unit 121 determines the size of the outer periphery of the front wheel friction circle based on the front wheel ground load Fzf acquired in step S701, and determines the size of the outer periphery of the rear wheel friction circle based on the rear wheel ground load Fzf acquired in step S701.

[0095] In step S703, the control unit 121 displays the front wheel friction circle and rear wheel friction circle whose sizes were determined in step S702 on a display (for example, a display of the meter unit MU) of the vehicle 1. Step S703 may be understood as a process of updating the display with the front wheel friction circle and rear wheel friction circle determined in step S702.

[0096] In step S704, the control unit 121 calculates the grip force of each of the front wheels FW and the rear wheels RW. Next, in step S705, the control unit 121 displays the grip force calculated in step S704 for each of the front wheels FW and the rear wheels RW as a vector superimposed on the friction circle (front wheel friction circle, rear wheel friction circle) on the display. A known technique may be used to calculate the grip force.

[0097] Fig. 18 shows an example of how the front wheel friction circle Cf and the rear wheel friction circle Cr are displayed on the display 200 of the meter unit MU. In the example of Fig. 18, a front wheel figure 201 that schematically represents the front wheels FW and a rear wheel figure 202 that schematically represents the rear wheels RW are displayed on the display 200. The front wheel friction circle Cf is superimposed on the front wheel figure 201, and the grip force of the front wheels FW is superimposed on the front wheel figure 201 and displayed as a vector VTf (arrow). Furthermore, the rear wheel friction circle Cr is superimposed on the rear wheel figure 202, and the grip force of the rear wheels RW is superimposed on the rear wheel figure 202 and displayed as a vector VTr (arrow).

[0098] As described above, in this embodiment, the size of the friction circle is determined based on the estimated value of the ground contact load, and the friction circle is displayed on the display of the vehicle 1. This allows the driver to operate the vehicle (driving / braking, etc.) while checking the grip force of the wheels using the friction circle.

[0099] Summary of Embodiments (Item 1) A control system (e.g., 100) for a saddle-riding type vehicle (e.g., 1) includes: a first detection unit (e.g., 111) that detects a vehicle vertical velocity (e.g., Vz) and a pitch angular velocity (e.g., ωy) occurring in a body (e.g., BD) of the saddle-riding type vehicle; a second detection unit (e.g., 112) that detects a state change in a front suspension mechanism (e.g., 9) that supports a front wheel (e.g., FW) of the saddle-riding type vehicle; and a control unit (e.g., 121) that controls the saddle-riding type vehicle based on the detection results of the first detection unit and the second detection unit. According to this item, the rear wheel ground load acting on the rear wheel can be estimated and the saddle-riding type vehicle can be controlled based on the estimated value without providing a stroke sensor in the rear suspension mechanism. In other words, it is possible to achieve both behavioral stability (ride comfort) and vehicle cost in the saddle-riding type vehicle.

[0100] (Item 2) The control system according to Item 1, wherein the control unit estimates a rear wheel ground load (e.g., Fzr) acting on a rear wheel (e.g., RW) of the saddle-riding type vehicle and controls the saddle-riding type vehicle based on the estimated value of the rear wheel ground load. According to this item, the rear wheel ground load acting on the rear wheel can be estimated and the saddle-riding type vehicle can be controlled based on the estimated value without providing a stroke sensor in the rear suspension mechanism. In other words, it is possible to achieve both behavioral stability (ride comfort) and vehicle cost in the saddle-riding type vehicle.

[0101] (Item 3) The control system according to Item 2, wherein the control unit calculates a front wheel ground load (e.g., Fzf) acting on the front wheels based on the detection results of the first detection unit and the second detection unit, and estimates the rear wheel ground load based on the front wheel ground load. According to this item, the rear wheel ground load can be estimated with high accuracy.

[0102] (Item 4) The control system according to Item 3, wherein the first detection unit detects the velocity in the vehicle up-down direction and the angular velocity in the pitch direction occurring at a representative position of the vehicle body, and the control unit calculates the front wheel ground load further based on a first distance (e.g., Lf) indicating the distance between the front suspension mechanism and the representative position in the vehicle longitudinal direction and the mass of the front axle. According to this item, the front wheel ground load can be estimated with high accuracy.

[0103] (Item 5) The control system according to item 4, wherein the second detection unit detects a stroke speed of the front suspension mechanism as a state change of the front suspension mechanism, and the control unit calculates the front wheel ground load Fzf by the following equation: Vpf=(Vz-Lf*ωy)-(∫Fzf / Mfdt), where ωy is the angular velocity in the pitch direction detected by the first detection unit, Vz is the velocity in the vehicle up-down direction detected by the first detection unit, Vpf is the stroke speed of the front suspension mechanism detected by the second detection unit, Lf is the first distance, and Mf is the mass of the front wheel. This item provides a specific method for calculating the front wheel ground load.

[0104] (Item 6) The control system according to any one of items 3 to 5, wherein the control unit obtains a difference in the state of the saddle-riding type vehicle between when the front wheel is affected by an obstacle (for example, an OB) and when the rear wheel is affected by the obstacle, and estimates a force converted from the front wheel ground load based on the difference as the rear wheel ground load. According to this item, even if the state of the vehicle differs between when the front wheel is affected by an obstacle and when the rear wheel is affected by the obstacle, the rear wheel ground load can be accurately determined from the front wheel ground load.

[0105] (Item 7) The control system according to any one of items 2 to 6, wherein the control unit controls a rear suspension mechanism supporting the rear wheels based on the estimated value of the rear wheel ground load. According to this item, the rear suspension mechanism can be controlled with high precision without providing a stroke sensor in the rear suspension mechanism. In other words, it is possible to achieve both behavioral stability (ride comfort) and vehicle cost in a saddle-type vehicle.

[0106] (Item 8) The control system according to Item 7, wherein the control unit calculates a stroke speed (e.g., Vpr) to be generated in the rear suspension mechanism based on the vehicle vertical velocity and the angular velocity in the pitch direction detected by the first detection unit and the estimated value of the rear wheel ground contact load, and controls the rear suspension mechanism based on the calculated stroke speed. According to this item, the stroke speed to be generated in the rear suspension mechanism can be determined with high accuracy.

[0107] (Item 9) The control system according to Item 8, wherein the first detection unit detects the velocity in the vehicle up-down direction and the angular velocity in the pitch direction occurring at a representative position of the vehicle body, and the control unit calculates the stroke velocity to be generated in the rear suspension mechanism further based on a second distance (e.g., Lr) indicating the distance between the rear suspension mechanism and the representative position in the vehicle longitudinal direction and the mass of a rear axle. According to this item, the stroke velocity to be generated in the rear suspension mechanism can be obtained with high accuracy.

[0108] (Item 10) The control system according to Item 9, wherein the control unit calculates a stroke speed Vpr to be generated in the rear suspension mechanism by the following equation: Vpr = (Vz + Lr * ωy) - (∫Fzr / Mrdt), where ωy is the angular velocity in the pitch direction detected by the first detection unit, Vz is the velocity in the vehicle up-down direction detected by the first detection unit, Lr is the second distance, Mr is the mass of the rear wheel, and Fzr is the estimated value of the rear wheel ground load. This item provides a specific method for calculating the stroke speed to be generated in the rear suspension mechanism.

[0109] (Item 11) The control system according to Item 9 or 10, further comprising an acquisition unit (e.g., 122) that acquires information indicating the weight distribution of an occupant and / or cargo in the saddle-riding type vehicle, and the control unit corrects the stroke speed generated in the rear suspension mechanism based on the information acquired by the acquisition unit. According to this item, the rear suspension mechanism can be accurately controlled in accordance with changes in the weight distribution of an occupant and / or cargo in the saddle-riding type vehicle. In other words, a decrease in the behavioral stability (ride comfort) of the saddle-riding type vehicle due to changes in the weight distribution can be suppressed.

[0110] (Item 12) The control system according to any one of items 2 to 11, wherein the saddle-riding type vehicle has a rear wheel ABS device (e.g., 132) that activates an antilock brake system (ABS) for a rear wheel brake (e.g., RB) of the saddle-riding type vehicle, and the control unit changes the ABS activation conditions in the rear wheel ABS device in accordance with the estimated value of the rear wheel ground load. According to this item, the ABS for the rear wheel brake can be appropriately activated so as to achieve both reduced slippage and reduced braking distance.

[0111] (Item 13) The control system according to Item 12 is characterized in that the control system includes a third detection unit (e.g., 114) that detects the wheel speed of the rear wheel, the ABS activation conditions in the rear wheel ABS device include a condition that the deceleration of the wheel speed of the rear wheel detected by the third detection unit is equal to or greater than a first threshold value (e.g., Awr), and the control unit changes the first threshold value in accordance with the estimated value of the rear wheel ground load. This item provides a specific method for appropriately activating the ABS for the rear wheel brake so as to achieve both reduced slip and reduced braking distance.

[0112] (Item 14) The control system according to Item 13, wherein the control unit increases the first threshold value as the estimated value of the rear wheel ground load increases. According to this item, it is possible to appropriately operate the ABS for the rear wheel brake so as to achieve both reduced slippage and reduced braking distance.

[0113] (Item 15) The control system according to any one of items 12 to 14, wherein the saddle-riding type vehicle has a front wheel ABS device (e.g., 131) that activates an antilock brake system (ABS) for a front wheel brake (e.g., FB) of the saddle-riding type vehicle, and the control unit calculates a front wheel ground load (e.g., Fzf) acting on the front wheel based on detection results from the first detection unit and the second detection unit, and changes ABS activation conditions in the front wheel ABS device according to the estimated value of the front wheel ground load. According to this item, the ABS for the front wheel brake can be appropriately activated so as to achieve both reduced slippage and reduced braking distance.

[0114] (Item 16) The control system according to any one of Items 2 to 15, wherein the saddle-ride type vehicle has a TCS device (e.g., 133) that activates a traction control system (TCS) for the rotational drive force of the rear wheels, and the control unit changes the TCS activation conditions in the TCS device in accordance with the estimated value of the rear wheel ground load. According to this item, the TCS can be appropriately activated to reduce spin of the rear wheels RW, which are drive wheels.

[0115] (Item 17) The control system according to Item 16, wherein the control system includes a third detection unit (e.g., 114) that detects the wheel speed of the rear wheels and a fourth detection unit (e.g., 113) that detects the wheel speed of the front wheels, wherein the TCS activation conditions in the TCS device include a condition that a ratio of the wheel speed of the rear wheels detected by the third detection unit to the wheel speed of the front wheels detected by the fourth detection unit is equal to or greater than a second threshold value (e.g., St), and wherein the control unit changes the second threshold value in accordance with an estimated value of the rear wheel ground load. According to this item, a specific method is provided for appropriately activating the TCS so as to reduce spin of the rear wheels RW, which are drive wheels.

[0116] (Item 18) The control system according to Item 17, wherein the control unit increases the second threshold value as the estimated value of the rear wheel ground load increases. According to this item, the TCS can be appropriately operated to reduce spin of the rear wheels RW, which are drive wheels.

[0117] (Item 19) A saddle-ride type vehicle (e.g., 1) including: a front suspension mechanism (e.g., 9) that supports a front wheel; a rear suspension mechanism (e.g., 11) that supports a rear wheel; and a control system (e.g., 100) according to any one of items 1 to 18. According to this item, a saddle-ride type vehicle is provided that can achieve both behavioral stability (ride comfort) and vehicle cost.

[0118] (Item 20) A control method for a saddle-riding type vehicle (e.g., 1), comprising: a first detection step of detecting a vehicle vertical velocity (e.g., Vz) and a pitch angular velocity (e.g., ωy) occurring in a body (e.g., BD) of the saddle-riding type vehicle; a second detection step of detecting a state change in a front suspension mechanism (e.g., 9) supporting a front wheel (e.g., FW) of the saddle-riding type vehicle; and a control step of controlling the saddle-riding type vehicle based on an estimated value of the rear wheel ground load, which is based on the detection results from the first and second detection steps. According to this item, the rear wheel ground load acting on the rear wheel can be estimated and the saddle-riding type vehicle can be controlled based on the estimated value, without providing a stroke sensor in the rear suspension mechanism. In other words, it is possible to achieve both behavioral stability (ride comfort) and vehicle cost in the saddle-riding type vehicle.

[0119] (Item 21) A program for causing a computer to execute the control method according to Item 20. According to this item, a program is provided that can achieve both behavioral stability (ride comfort) and vehicle cost in a saddle-type vehicle.

[0120] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention.

[0121] 1: saddle-ride type vehicle, 2: power unit, 9: front suspension mechanism, 11: rear suspension mechanism, FW: front wheel, FB: front wheel brake, RW: rear wheel, RB: rear wheel brake, BD: vehicle body, MU: meter unit, 111: inertia sensor, 112: stroke sensor, 113: rear wheel speed sensor, 114: front wheel speed sensor, 121: control unit

Claims

1. A control system for a saddle-riding type vehicle, comprising: a first detection unit that detects the vertical velocity and pitch angular velocity of the vehicle body of the saddle-riding type vehicle; a second detection unit that detects changes in the state of a front suspension mechanism that supports the front wheels of the saddle-riding type vehicle; and a control unit that controls the saddle-riding type vehicle based on the detection results of the first detection unit and the second detection unit.

2. The control system according to claim 1, wherein the control unit estimates a rear wheel ground load acting on the rear wheels of the saddle-riding type vehicle and controls the saddle-riding type vehicle based on the estimated value of the rear wheel ground load.

3. The control system described in claim 2, characterized in that the control unit calculates the front wheel ground load acting on the front wheels based on the detection results of the first detection unit and the second detection unit, and estimates the rear wheel ground load based on the front wheel ground load.

4. The control system described in claim 3, characterized in that the first detection unit detects the vehicle vertical velocity and the angular velocity in the pitch direction occurring at a representative position of the vehicle body, and the control unit calculates the front wheel ground load further based on a first distance indicating the distance between the front suspension mechanism and the representative position in the vehicle longitudinal direction and the mass of the front axle.

5. The control system described in claim 4, wherein the second detection unit detects a stroke speed of the front suspension mechanism as a change in state of the front suspension mechanism, and the control unit calculates the front wheel ground load Fzf by the following equation: Vpf = (Vz - Lf * ωy) - (∫Fzf / Mfdt), where ωy is the angular velocity in the pitch direction detected by the first detection unit, Vz is the velocity in the vehicle's vertical direction detected by the first detection unit, Vpf is the stroke speed of the front suspension mechanism detected by the second detection unit, Lf is the first distance, and Mf is the mass of the front wheel.

6. A control system as described in any one of claims 3 to 5, characterized in that the control unit obtains the difference in the state of the saddle-type vehicle when the front wheel is affected by an obstacle and when the rear wheel is affected by the obstacle, and estimates the force converted from the front wheel ground load as the rear wheel ground load based on the difference.

7. A control system according to any one of claims 2 to 6, characterized in that the control unit controls a rear suspension mechanism supporting the rear wheels based on the estimated value of the rear wheel ground load.

8. The control system described in claim 7, characterized in that the control unit calculates a stroke speed to be generated in the rear suspension mechanism based on the vehicle vertical velocity and pitch angular velocity detected by the first detection unit and an estimated value of the rear wheel ground load, and controls the rear suspension mechanism based on the stroke speed.

9. The control system described in claim 8, characterized in that the first detection unit detects the vehicle vertical velocity and the angular velocity in the pitch direction occurring at a representative position of the vehicle body, and the control unit calculates the stroke velocity to be generated in the rear suspension mechanism further based on a second distance indicating the distance between the rear suspension mechanism and the representative position in the vehicle longitudinal direction and the mass of the rear axle.

10. The control system described in claim 9, wherein the control unit calculates the stroke speed Vpr to be generated in the rear suspension mechanism by the following formula: Vpr = (Vz + Lr * ωy) - (∫Fzr / Mrdt), where ωy is the angular velocity in the pitch direction detected by the first detection unit, Vz is the vehicle vertical speed detected by the first detection unit, Lr is the second distance, Mr is the mass of the rear wheel, and Fzr is the estimated value of the rear wheel ground load.

11. A control system as described in claim 9 or 10, characterized in that the control system includes an acquisition unit that acquires information indicating the weight distribution of occupants and / or cargo of the saddle-ride type vehicle, and the control unit corrects the stroke speed generated in the rear suspension mechanism based on the information acquired by the acquisition unit.

12. A control system according to any one of claims 2 to 11, characterized in that the saddle-riding vehicle has a rear wheel ABS device that activates an anti-lock brake system (ABS) for the rear wheel brakes of the saddle-riding vehicle, and the control unit changes the ABS activation conditions in the rear wheel ABS device in accordance with the estimated value of the rear wheel ground load.

13. The control system described in claim 12, characterized in that the control system includes a third detection unit that detects the wheel speed of the rear wheel, the ABS activation conditions in the rear wheel ABS device include a condition that the deceleration of the wheel speed of the rear wheel detected by the third detection unit is equal to or greater than a first threshold, and the control unit changes the first threshold in accordance with an estimated value of the rear wheel ground load.

14. The control system according to claim 13, wherein the control unit increases the first threshold value as the estimated value of the rear wheel ground load increases.

15. A control system as claimed in any one of claims 12 to 14, characterized in that the saddle-ride type vehicle has a front wheel ABS device that activates an anti-lock brake system (ABS) for the front wheel brakes of the saddle-ride type vehicle, and the control unit calculates a front wheel ground load acting on the front wheel based on the detection results of the first detection unit and the second detection unit, and changes the ABS operation conditions in the front wheel ABS device according to the estimated value of the front wheel ground load.

16. A control system as claimed in any one of claims 2 to 15, characterized in that the saddle-ride type vehicle has a traction control system (TCS) device that activates a TCS in response to the rotational driving force of the rear wheel, and the control unit changes the TCS operating conditions in the TCS device in accordance with an estimated value of the rear wheel ground load.

17. The control system according to claim 16, characterized in that the control system comprises a third detection unit that detects the wheel speed of the rear wheels and a fourth detection unit that detects the wheel speed of the front wheels, the TCS operation conditions in the TCS device include a condition that the ratio of the wheel speed of the rear wheels detected by the third detection unit to the wheel speed of the front wheels detected by the fourth detection unit is equal to or greater than a second threshold value, and the control unit changes the second threshold value according to an estimated value of the rear wheel ground load.

18. The control system according to claim 17, wherein the control unit increases the second threshold value as the estimated value of the rear wheel ground load increases.

19. A saddle-type vehicle comprising: a front suspension mechanism for supporting a front wheel; a rear suspension mechanism for supporting a rear wheel; and a control system according to any one of claims 1 to 18.

20. A control method for a saddle-riding type vehicle, comprising: a first detection step of detecting a vehicle vertical velocity and a pitch angular velocity occurring in a body of the saddle-riding type vehicle; a second detection step of detecting a change in the state of a front suspension mechanism supporting the front wheels of the saddle-riding type vehicle; and a control step of controlling the saddle-riding type vehicle based on the detection results in the first detection step and the second detection step.

21. A program for causing a computer to execute the control method according to claim 20.

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