Vehicular driving assistance system

Abstract

A vehicular driving assistance system (S) is to be installed on a saddle-type vehicle (1) that comprises a rear wheel (42) that is a vehicle drive wheel and a front wheel (32) that is a driven wheel. When an object that is positioned in the advancement direction of the saddle-type vehicle (1) has been recognized to be an obstacle, a control unit (104) that adjusts the drive force or braking force at the rear wheel (42) so as to control a front wheel lift amount that indicates the degree to which the front wheel (32) moves in a lifting direction from a road surface (R) executes suppression processing that suppresses the front wheel lift amount to reduce the front wheel lift amount as compared to when an object has not been recognized to be an obstacle.

Description

Vehicle driving support system

[0001] The present invention relates to a vehicle driving support system.

[0002] In vehicles such as saddle-riding vehicles, the vehicle weight is light relative to the driving torque (driving force), which is the actual torque of the drive wheels transmitted from the drive wheels to the road surface by the output of the driving source. Therefore, due to sudden opening operations of an accelerator operating member, sudden engagement operations of a manual clutch, or the like, a lift-up (front wheel lift: wheelie) state, in which only the front wheel lifts off the road surface while the rear wheel, which is the drive wheel, remains grounded, tends to easily occur.

[0003] In such vehicles, when a lift-up (front wheel lift: wheelie) state occurs, the front wheel lifts up and the vehicle posture becomes self-supporting on only the rear wheel, which tends to create a risk of leading to vehicle overturning or the like. On the other hand, driving the vehicle in such a wheelie state tends to be an attractive driving state that allows the driver of the vehicle to enjoy the fun of driving, including freedom of driving and acceleration performance.

[0004] Under such circumstances, Patent Document 1 relates to a control device used for a motorcycle, a control method used for a motorcycle, and a target torque determination method. In a configuration in which the setting unit 25 has set to the first mode, when the wheelie determination unit 21 determines that a wheelie has occurred in the motorcycle 100, the torque determination unit 24 of the second control device 20 changes the target torque for controlling the output torque of the engine 32 to a value that is reduced compared to the target torque before the wheelie determination unit 21 determined that a wheelie has occurred. On the other hand, in a state where the setting unit 25 has set to the second mode, when the wheelie determination unit 21 determines that a wheelie has occurred, the torque determination unit 24 sets the target torque to a value that is larger than the target torque set when the wheelie determination unit 21 determines that a wheelie has occurred in the first mode. This configuration is disclosed.

[0005] Japanese Patent No. 6913551

[0006] However, according to the inventors' research, while the configuration disclosed in Patent Document 1 is intended to improve the degree of freedom when driving a saddle-type vehicle such as a motorcycle, it does not disclose or suggest the necessity of keeping the external detection equipment, such as a camera, track objects that may be obstacles in front of the vehicle, in order to avoid losing sight of them when an advanced driver-assistance system (ADAS) is installed in the saddle-type vehicle. Therefore, there is room for improvement in this respect.

[0007] The present invention was made after the above considerations, and aims to provide a vehicle driving assistance system that ensures the freedom of driving of a saddle-type vehicle equipped with an advanced driver assistance system that includes external environment detection equipment, while enabling the external environment detection equipment to continuously detect objects that may become obstacles.

[0008] To achieve the above objectives, in one aspect of the present invention, a vehicle driving support system is provided, which is mounted on a saddle-type vehicle equipped with a rear wheel which is a driving wheel and a front wheel which is a driven wheel, and includes a control unit that controls the amount of front wheel lift, which indicates the degree to which the front wheel moves in a direction away from the road surface, by adjusting the driving force of the rear wheel or the braking force of the rear wheel, wherein when an object located in the direction of travel of the saddle-type vehicle is recognized as an obstacle, the control unit performs a suppression process to suppress the amount of front wheel lift so that the amount of front wheel lift is smaller than when the object is not recognized as an obstacle.

[0009] According to the vehicle driving support system in one aspect of the present invention described above, when the control unit recognizes an object located in the direction of travel of the saddle-type vehicle 1 as an obstacle, it performs a suppression process to reduce the amount of front wheel lift compared to when the object is not recognized as an obstacle. Therefore, it is possible to realize a vehicle driving support system that ensures the freedom of driving of a saddle-type vehicle equipped with an advanced driving support system that includes external detection equipment, while enabling the external detection equipment to continuously detect objects that may become obstacles.

[0010] Figure 1 is a side view showing the right side of a vehicle equipped with the vehicle driving assistance system according to an embodiment of the present invention. Figure 2 is a block diagram showing the configuration of the vehicle driving assistance system according to this embodiment. Figure 3 is a time chart showing an example of vehicle torque, wheel speed, and front wheel lift when there are no obstacles in the direction of travel of the vehicle equipped with the vehicle driving assistance system according to this embodiment and the first embodiment is selected. Figure 4 is a time chart showing an example of vehicle torque, wheel speed, and front wheel lift when there are obstacles in the direction of travel of the vehicle equipped with the vehicle driving assistance system according to this embodiment and the first embodiment is selected. Figure 5 is a time chart showing an example of vehicle torque, wheel speed, and front wheel lift when there are no obstacles in the direction of travel of the vehicle equipped with the vehicle driving assistance system according to this embodiment and the second embodiment is selected. Figure 6 is a time chart showing an example of vehicle torque, wheel speed, and front wheel lift when there are obstacles in the direction of travel of the vehicle equipped with the vehicle driving assistance system according to this embodiment and the second embodiment is selected.

[0011] The vehicle driving assistance system according to an embodiment of the present invention will be described in detail below with reference to the drawings as appropriate. In the drawings, the x, y, and z axes form a three-axis orthogonal coordinate system. The x axis is the longitudinal (front-to-back) direction, with the forward direction being the direction of travel and indicated as the positive direction of the x axis. The y axis is the width (left-to-right) direction, with the left direction being indicated as the positive direction of the y axis. The z axis is the vertical direction, with the upward direction being indicated as the positive direction of the z axis.

[0012] [Vehicle Configuration] First, with reference to Figure 1, the configuration of the vehicle to which the vehicle driving assistance system in this embodiment is applied will be described in detail.

[0013] Figure 1 is a side view showing the right side of a vehicle to which the vehicle driver assistance system in this embodiment is applied.

[0014] As shown in Figure 1 as a typical example of a saddle-type vehicle, a motorcycle, the vehicle 1 typically comprises a body (sometimes including support members, etc., fixed to the frame members, which are not shown) 10, represented by a frame member, which is a metal body frame member such as a steel pipe; a drive source 20, which is an internal combustion engine; a steering front suspension mechanism 30 that steers the driven front wheel 32; and a rear suspension mechanism 40 that steers the driven rear wheel 42. When the drive source 20 is an engine, as shown in detail in Figure 2, a spark plug 22 for the ignition system, an injector 24 for the fuel injection system, and a throttle valve 26 for the electronically controlled throttle system are attached to the engine. Also, when the drive source 20 is an engine, a transmission T is typically attached between the drive source 20 and the driven rear wheel 42 via a clutch, which is not shown. In addition to motorcycles, the saddle-type vehicle may also be a small, lightweight three-wheeled or four-wheeled vehicle such as a buggy. Furthermore, the drive source 20 may be an engine, an electric motor replacing the engine, or a combination of an engine and an electric motor.

[0015] More specifically, the steering front suspension mechanism 30 typically includes a telescopic front fork 34 that suspends a front wheel 32 having an axle 32a and is mounted on a support member (not shown) of the vehicle body 10, a steering stem 36 mounted on a support member (not shown) of the vehicle body 10, and a handle 38 that is an operating member for steering the front wheel 32 and is fixed to the steering stem 36. In addition, a front wheel brake FB is provided for the front wheel 32, which brakes the front wheel 32 in response to the closing operation of a brake lever (not shown), which is a brake operating member.

[0016] The rear suspension mechanism 40 has a swing arm 44 that pivots freely on a pivot axis (not shown) set in the vehicle body 10 and has a rear wheel 42 having an axle 42a in a predetermined geometry, and a rear spring damper unit 46 that suspends the rear wheel 42. In addition, a rear wheel brake RB is provided for the rear wheel 42, which brakes the rear wheel 42 in response to the pressing motion of a brake pedal (not shown), which is a brake operating member. The front wheel brake FB and the rear wheel brake RB constitute the brake mechanism of the vehicle 1.

[0017] Furthermore, the vehicle 1 includes a crank angle sensor 141 that detects the rotation angle of the crankshaft (not shown) when the drive source 20 is an engine and outputs an electrical signal indicating the detected rotation angle to the electronic control unit 100; an accelerator position sensor 142 that detects the opening (accelerator opening), which is the amount of operation of the accelerator grip 38a, which is an accelerator operating member mounted on the steering wheel 38 of the vehicle 1, and outputs an electrical signal indicating the detected accelerator opening to the electronic control unit 100; a throttle position sensor 143 that detects the opening (throttle opening) of the throttle valve 26 and outputs an electrical signal indicating the detected throttle opening to the electronic control unit 100; an operating interface such as a switch for selecting a driving mode mounted on the steering wheel 38 of the vehicle 1, which outputs an electrical signal indicating the selected driving mode to the electronic control unit 100; and a front wheel speed, which is the rotational speed of the front wheels 32, and outputs an electrical signal indicating the detected front wheel speed. A front wheel speed sensor 145 outputs an electrical signal to the electronic control unit 100; a rear wheel speed sensor 146 detects the rear wheel speed, which is the rotational speed of the rear wheel 42, and outputs an electrical signal to the electronic control unit 100 indicating the detected rear wheel speed; a front wheel stroke sensor 147 detects the stroke amount (front wheel stroke amount) of the telescopic front fork 34 of the steering front suspension mechanism 30 and outputs an electrical signal to the electronic control unit 100 indicating the detected front wheel stroke amount; a rear wheel stroke sensor 148 detects the stroke amount (rear wheel stroke amount) of the rear spring damper unit 46 of the rear suspension mechanism 40 and outputs an electrical signal to the electronic control unit 100 indicating the detected rear wheel stroke amount; and an inertial measuring device (IMU) detects the vertical acceleration of the vehicle body 10 and the pitch angular velocity of the vehicle body 10, and outputs electrical signals to the electronic control unit 100 indicating the detected vertical acceleration and pitch angular velocity. The system includes a Measurement Unit (149) and an external environment detection device (200) that detects and acquires information about the external environment of the vehicle 1, including preceding vehicles in the direction of travel of the vehicle 1, and outputs an electrical signal indicating the acquired information about the external environment to the electronic control device (100).

[0018] Here, the IMU 149 is mounted on the vehicle body 10 or its support member (not specified in the reference numerals) between the axle 32a of the front wheel 32 and the axle 42a of the rear wheel 42 in the longitudinal (front-rear) direction of the vehicle body 10. The pitch direction typically refers to the rotational direction around the pitch axis that extends in the width (left-right) direction through the center of gravity of the vehicle 1, and the pitch angular velocity refers to the angular velocity of rotation around the pitch axis. Alternatively, instead of the IMU 149, a pitch rate sensor for detecting the pitch angular velocity or an acceleration sensor for detecting vertical acceleration may be provided. The external environment detection device 200 is mounted on the vehicle body 10 or its support member (not specified in the reference numerals) so as to have a predetermined detection range corresponding to the required detection target range in the direction of travel (forward direction) of the vehicle 1, and is typically a monocular or stereo optical camera that acquires imaging information of the external environment in the direction of travel of the vehicle 1 within a predetermined imaging range. Furthermore, the external environment detection device 200 may have a millimeter-wave radar and LiDAR (Laser Imaging Detection and Ranging), etc., instead of or in combination with an optical camera.

[0019] [Configuration of the Vehicle Driving Support System] Next, with further reference to Figure 2, the configuration of the vehicle driving support system S, including the electronic control unit 100 in this embodiment, will be described.

[0020] Figure 2 is a block diagram showing the configuration of the vehicle driving support system S in this embodiment.

[0021] As shown in Figure 2, the electronic control unit 100 in this embodiment is mounted on a vehicle 1, which is a saddle-type vehicle such as a motorcycle, with the rear wheels 42 as drive wheels and the front wheels 32 as driven wheels, and is composed of an ECU (Electronic Control Unit) and the like. The electronic control unit 100 is electrically connected to a crank angle sensor 141, an accelerator position sensor 142, a throttle position sensor 143, a driving mode selection member 144, a front wheel speed sensor 145, a rear wheel speed sensor 146, a front wheel stroke sensor 147, a rear wheel stroke sensor 148, an IMU 149, and an external environment detection device 200. Note that the waveform shaping circuits and A / D (Analog / Digital) conversion circuits and other input circuits related to these various sensors are not shown in the figure.

[0022] The electronic control device 100 includes a processing unit 102 having a front wheel lift determination unit 102a, a front wheel lift amount calculation unit 102b, and an obstacle determination unit 102c, a control unit 104, and a storage unit M. The processing unit 102 having the front wheel lift determination unit 102a, the front wheel lift amount calculation unit 102b, and the obstacle determination unit 102c, and the control unit 104 are shown as functional blocks when the CPU (Central Processing Unit), which is not shown in the figures, reads arithmetic processing programs and data stored in the storage unit M, which is typically memory, as needed and executes arithmetic processing. The storage unit M also has data pre-stored in it that has multiple driving modes, each of which defines a target value for the front wheel lift amount. The driver of the vehicle 1 can select one of these multiple driving modes or switch one of the driving modes to another by operating the driving mode selection member 144.

[0023] The front wheel lift determination unit 102a determines whether or not front wheel lift has begun, in which the front wheel 32 moves away from the road surface R and lifts up. Here, depending on the specifications such as the extension stroke amount of the telescopic front fork 34 of the steering front suspension mechanism 30, the front wheel lift determination unit 102a may determine that front wheel lift has begun not only when the front wheel 32 is actually away from the road surface R, but also when the front wheel 32 is just before it leaves the road surface R. Furthermore, from the standpoint of the front wheel lift determination unit 102a appropriately determining whether or not front wheel lift has begun, it is preferable that the front wheel lift determination unit 102a determines that front wheel lift has begun when an upward vertical acceleration of the vehicle body 10, indicated by the electrical signal output from the IMU 149, occurs, and when this acceleration shows an increasing trend. This is a prerequisite for the front wheel lift amount calculation unit 102b to appropriately start calculating the front wheel lift amount, which indicates the degree of front wheel lift, and to calculate the front wheel lift amount with accuracy. Furthermore, from a similar viewpoint, the front wheel lift determination unit 102a may determine that front wheel lift has begun when the value corresponding to the difference or ratio between the front wheel speed indicated by the electrical signal output from the front wheel speed sensor 145 and the rear wheel speed indicated by the electrical signal output from the rear wheel speed sensor 146 exceeds a predetermined value. Furthermore, from a similar viewpoint, the front wheel lift determination unit 102a may determine that front wheel lift has begun when the increase in the extension direction front wheel stroke amount of the telescopic front fork 34 indicated by the electrical signal output from the front wheel stroke sensor 147 exceeds a predetermined value, or when the increase in the compression direction rear wheel stroke amount of the rear spring damper unit 46 indicated by the electrical signal output from the rear wheel stroke sensor 148 exceeds a predetermined value.

[0024] The front wheel lift amount calculation unit 102b calculates the front wheel lift amount, which is an estimated value of the lift amount of the front wheels 32 relative to the road surface R, by calculating the amount of change in the angle of rotation of the vehicle body 10 in the direction in which the front wheels 32 move away from the road surface R, starting from the time when the front wheel lift determination unit 102a determines that front wheel lift has started to occur. Specifically, the front wheel lift amount calculation unit 102b calculates the front wheel lift amount by accumulating the pitch angular velocity, which is the detected value indicated by the electrical signal output from the IMU 149, starting from the time when the front wheel lift determination unit 102a determines that front wheel lift has started to occur. In this case, from the standpoint of calculating the front wheel lift amount more appropriately, it is preferable that the front wheel lift amount calculation unit 102b sets the angular position of the vehicle body 10 around the pitch axis (the angular position of the vehicle body 10 in the rotational direction of the vehicle body 10 as the front wheels 32 move away from the road surface R, and the rotational direction of the vehicle body 10 around the pitch axis) at the time the front wheel lift determination unit 102a determines that front wheel lift has begun to occur as the reference value for the calculation.

[0025] The obstacle determination unit 102c calculates the distance between the vehicle 1 and an object, such as a preceding vehicle, in the direction of travel of the vehicle 1, based on an electrical signal indicating information about the external environment of the vehicle 1 output from the external environment detection device 200 and input to the electronic control device 100. If it determines that this distance is less than or equal to a predetermined distance, it recognizes the object as an obstacle in the direction of travel of the vehicle 1. On the other hand, if it determines that this distance exceeds the predetermined distance, it recognizes the object as not being an obstacle in the direction of travel of the vehicle 1 (it does not recognize the object as an obstacle in the direction of travel of the vehicle 1). In this case, the obstacle determination unit 102c may further consider the speed of the vehicle 1 and the relative speed between the vehicle 1 and the object, such as a preceding vehicle, in order to determine whether or not the object, such as a preceding vehicle, in the direction of travel of the vehicle 1 is an obstacle. Alternatively, this function of the obstacle determination unit 102c may be separated from the electronic control device 100 and provided to the external environment detection device 200, thereby configuring an external environment detection device with an obstacle determination and recognition function.

[0026] The control unit 104 controls the engine's operating state by controlling the ignition operation of the spark plug 22 via a secondary coil (not shown), the fuel injection operation of the injector 24, and the opening degree (throttle opening) of the throttle valve 26 via a throttle motor (not shown) when the drive source 20 is an engine, based on the detected values ​​indicated by the respective electrical signals from the rotational speed sensor of the drive source 20, such as the crank angle sensor 141, the accelerator position sensor 142, and the throttle position sensor 143 when the drive source 20 is an engine. When the drive source 20 is an engine, the control unit 104 controls the operating state of the electric motor by controlling the switching operation of the electric motor's drive circuit. When the drive source 20 is an electric motor, the control unit 104 controls the operating state of the electric motor by adjusting the hydraulic pressure (brake pressure) of a master cylinder (not shown), etc.

[0027] Furthermore, the control unit 104, from the viewpoint of ensuring the freedom of driving the vehicle 1 while enabling the external detection device 200 to continue detecting objects that may become obstacles, adjusts at least one of the driving state of the drive source 20 and the operating state of the rear brake RB based on the front wheel lift amount calculated as an estimated value by the front wheel lift amount calculation unit 102b, thereby performing control processing to control the actual front wheel lift amount of the vehicle 1 by adjusting at least one of the driving force of the rear wheels 42 and the braking force of the rear wheels 2. More specifically, from the viewpoint of controlling the front wheel lift amount of the vehicle 1 more appropriately, when the obstacle determination unit 102c recognizes an object located in the direction of travel (forward) of the vehicle 1 as an obstacle, the control unit 104 performs suppression processing to suppress the front wheel lift amount so that it is smaller than when the obstacle determination unit 102c does not recognize such object as an obstacle. Furthermore, when the obstacle detection unit 102c does not recognize an object located in the direction of travel of the vehicle 1 as an obstacle, and the control unit 104 controls the amount of front wheel lift to suppress it, such control process for the amount of front wheel lift may be called a suppression process.

[0028] Furthermore, from the viewpoint of appropriately reflecting the driver's intentions in the driving state of the vehicle 1, it is preferable that the control unit 104, based on the driving mode selected or switched by the driver operating the driving mode selection member 144, refers to data having multiple driving modes that are stored in the storage unit M and define target values ​​for the front wheel lift amount for each of the multiple driving modes, obtains a target value corresponding to the driving mode selected or switched by the driver, and controls the front wheel lift amount to approach this target value. In this case, from the viewpoint of more appropriately controlling the front wheel lift amount of the vehicle 1, it is preferable that when the obstacle determination unit 102c recognizes an object located in the direction of travel of the vehicle 1 as an obstacle, the control unit 104 uses a target value that is relatively smaller than the target value when the obstacle determination unit 102c does not recognize such object as an obstacle to perform the suppression process. Furthermore, in this case, from the viewpoint of more appropriately and reliably controlling the front wheel lift amount of the vehicle 1, it is preferable that the control unit 104, when the obstacle determination unit 102c recognizes an object located in the direction of travel of the vehicle 1 as an obstacle, forcibly switches from a first mode (e.g., sport mode) that was in place before the obstacle determination unit 102c recognized an object located in the direction of travel of the vehicle 1 as an obstacle, to a second mode (e.g., comfort mode) that defines a target value relatively smaller than the target value defined by the first mode. Also, from the viewpoint of more appropriately controlling the front wheel lift amount of the vehicle 1, it is preferable that the control unit 104 performs feedback control so that the front wheel lift amount calculated as an estimated value by the front wheel lift amount calculation unit 102b approaches the target value corresponding to the driving mode selected or switched by the driver.

[0029] Furthermore, from the viewpoint of more appropriately controlling the amount of front wheel lift of the vehicle 1, it is preferable that the control unit 104 performs a suppression process when the obstacle determination unit 102c recognizes an object located in the direction of travel of the vehicle 1 as an obstacle at the time the front wheel lift determination unit 102a determines that front wheel lift has begun to occur. Also, from the viewpoint of more appropriately controlling the amount of front wheel lift of the vehicle 1, it is preferable that in the suppression process, the amount of front wheel lift is reduced by decreasing the amount of change per unit time of the rotational speed of the rear wheels 42. In this case, from the viewpoint of more appropriately and reliably controlling the amount of front wheel lift of the vehicle 1, it is preferable that the control unit 104 adjusts the driving force of the rear wheels 42 by adjusting the output of the drive source 20, which includes at least one of the engine and electric motor. Also, from a similar viewpoint, it is preferable that the control unit 104 adjusts the braking force of the rear wheels 42 by adjusting the brake pressure of the brake mechanism of the vehicle 1, that is, the brake pressure of the rear brake RB, and as a result adjusts the driving force of the rear wheels 42. Note that the adjustment of the output of the drive source 20 and the adjustment of the brake pressure of the rear brake RB may be performed together.

[0030] [Operation of the Vehicle Driving Assistance System] Next, referring to Figures 3 to 6, the operation of the electronic control device 100 of the vehicle driving assistance system S in this embodiment will be explained in detail, using as an example the case in which the drive source 20 is the engine and the amount of front wheel lift is controlled by adjusting the engine output to adjust the driving force of the rear wheels 42.

[0031] Figure 3 is a time chart showing an example of the torque, wheel speed, presence or absence of front wheel lift, and presence or absence of obstacles for the vehicle 1 equipped with the vehicle driving support system S in this embodiment when there are no obstacles (not recognized) in the direction of travel of the vehicle 1 and the first mode (e.g., sport mode) is selected. Figure 4 is a time chart showing an example of the torque, wheel speed, presence or absence of front wheel lift, and presence or absence of obstacles for the vehicle 1 equipped with the vehicle driving support system S in this embodiment when there are obstacles (recognized) in the direction of travel of the vehicle 1 and the first mode is selected. Figure 5 shows the vehicle driving in this embodiment. Figure 4 and Figure 6 are time charts showing an example of the torque, wheel speed, presence or absence of front wheel lift, and presence or absence of obstacles for vehicle 1 when there are no obstacles (not recognized) in the direction of travel of vehicle 1 equipped with the support system S and the second mode (for example, comfort mode: which defines a target value that is relatively smaller than the target value defined in the first mode) is selected. Figure 6 is a time chart showing an example of the torque, wheel speed, presence or absence of front wheel lift, and presence or absence of obstacles for vehicle 1 when there are obstacles (recognized) in the direction of travel of vehicle 1 equipped with the vehicle driving support system S in this embodiment and the second mode is selected. Note that in Figures 4 and 6, objects recognized as obstacles are shown as other vehicles.

[0032] As shown in Figure 3, where the first mode (e.g., sport mode) is selected as the driving mode, if the obstacle detection unit 102c continues to recognize that there are no obstacles in the direction of travel of the vehicle 1 for the entire period (other vehicles not shown are not obstacles), then at time t1, the front wheel lift detection unit 102a determines that front wheel lift has begun, and in response, the control unit 104 begins to execute control processing to suppress the amount of front wheel lift. As a result, the required torque, which is determined based on the accelerator opening due to the driver's accelerator operation, continues to increase from T1, but the rear wheel torque, which corresponds to the driving force of the rear wheels 42, begins to decrease from T1 to T2. Also, at time t1, the rear wheel speed continues to increase from v1, but the front wheel speed begins to decrease from v1. Then, at time t2, the rear wheel torque becomes T2, and at time t3, the required torque begins to decrease from T3 due to the driver's closing accelerator operation (θ1 is an example of the angle corresponding to the amount of front wheel lift during this period). Next, at time t4, the requested torque becomes T2 and matches the rear wheel torque that was substantially maintained at T2, and the rear wheel torque begins to follow the requested torque. At time 5, the driver's closing accelerator operation begins to be maintained at a constant opening, and the requested torque and rear wheel torque begin to be maintained at a substantially constant value of T4. Then, at time t6, the front wheel lift determination unit 102a determines that the front wheel lift has been eliminated, and from time t6 to time t7, the front wheel speed substantially matches the rear wheel speed v3.

[0033] Next, as shown in Figure 4, where the first mode (e.g., sport mode) is selected as the driving mode, if at time t11 the obstacle detection unit 102c recognizes that an obstacle exists in the direction of travel of the vehicle 1 (other vehicles are obstacles), then at time t12 the front wheel lift detection unit 102a determines that front wheel lift has begun, and in response, the control unit 104 begins to execute a suppression process to further suppress the amount of front wheel lift. As a result, the required torque, which is determined based on the accelerator opening angle due to the driver's accelerator operation, continues to increase from T11, but the rear wheel torque, which corresponds to the driving force of the rear wheels 42, begins to decrease from T11 to T12. In this case, the target value for the front wheel lift is set to a relatively smaller value compared to the case where the obstacle detection unit 102c, as shown in Figure 3, continues to recognize that there are no obstacles in the direction of travel of vehicle 1 for the entire period (other vehicles are not obstacles). As a result, the front wheel lift becomes relatively smaller (the angle θ2 corresponding to the front wheel lift becomes relatively smaller than the angle θ1 in Figure 3), and the value T12 at which the rear wheel torque begins to decrease also becomes relatively smaller than the value T2 in Figure 3. Also, at time t12, the rear wheel speed continues to increase from v11, but the front wheel speed begins to decrease from v11. Then, at time t13, the rear wheel torque becomes T12, and at time t14, the front wheel lift detection unit 102a determines that the front wheel lift has been eliminated, and from time t14 to time t15, the front wheel speed substantially matches the rear wheel speed v13. Next, at time t16, the required torque begins to decrease from T13 due to the driver's closing accelerator operation. Then, at time t17, as the required torque becomes T12, the rear wheel torque begins to follow the required torque, matching the rear wheel torque that was substantially maintained at T12. At time 18, the driver's closing accelerator operation begins to be maintained at a constant opening, and the required torque and rear wheel torque begin to be maintained at a substantially constant value of T14.

[0034] Next, as shown in Figure 5, where the second mode (e.g., comfort mode) is selected as the driving mode, if the obstacle detection unit 102c continues to recognize that there are no obstacles in the direction of travel of the vehicle 1 for the entire period (other vehicles not shown are not obstacles), then at time t21, the front wheel lift detection unit 102a determines that front wheel lift has begun, and in response, the control unit 104 begins to execute control processing to suppress the amount of front wheel lift. As a result, the required torque, which is determined based on the accelerator opening due to the driver's accelerator operation, continues to increase from T21, but the rear wheel torque, which corresponds to the driving force of the rear wheels 42, begins to decrease from T21 to T22. In this case, the target value of the front wheel lift is set to a relatively smaller target value obtained by subtracting a predetermined value from the target value when the first mode (e.g., sport mode) is selected as the driving mode as shown in Figure 3. As a result, the front wheel lift becomes relatively smaller (the angle θ3 corresponding to the front wheel lift becomes relatively smaller than the angle θ1 in Figure 3), and the value T22 at which the rear wheel torque begins to decrease also becomes relatively smaller than the value T2 in Figure 3. Furthermore, from the viewpoint of simplification in setting target values, the target value of the front wheel lift when the second mode is selected and the target value of the front wheel lift when the first mode is selected and the obstacle detection unit 102c recognizes that there is an obstacle in the direction of travel of the vehicle 1 (other vehicles are obstacles) may be set to be equal to each other. Also, at time t21, the rear wheel speed continues to increase from v21, but the front wheel speed begins to decrease from v21. Then, at time t22, the rear wheel torque becomes T22, and at time t23, the front wheel lift determination unit 102a determines that the front wheel lift has been eliminated, and from time t23 to time t24, the front wheel speed substantially matches the rear wheel speed v23. Then, at time t25, the required torque begins to decrease from T23 due to the driver's closing accelerator operation. Then, at time t26, as the required torque becomes T22 and matches the rear wheel torque which was substantially maintained at T22, the rear wheel torque begins to follow the required torque, and at time t27, the driver's closing accelerator operation begins to be maintained at a constant opening, and the required torque and rear wheel torque begin to be maintained at substantially constant values ​​of T24.

[0035] Next, as shown in Figure 6, where the second mode (e.g., comfort mode) is selected as the driving mode, if at time t31 the obstacle detection unit 102c recognizes that an obstacle exists in the direction of travel of vehicle 1 (other vehicles are obstacles), then at time t32 the front wheel lift detection unit 102a determines that front wheel lift has begun, and in response, the control unit 104 begins to execute a suppression process to further suppress the amount of front wheel lift. As a result, the required torque, which is determined based on the accelerator opening angle due to the driver's accelerator operation, continues to increase from T31, but the rear wheel torque, which corresponds to the driving force of the rear wheels 42, begins to decrease from T31 to T32. In this case, the target value of the front wheel lift amount is set to a relatively smaller target value obtained by subtracting a predetermined value from the target value, compared to the case where the obstacle detection unit 102c continues to recognize that there are no obstacles in the direction of travel of vehicle 1 (other vehicles are not obstacles) for the entire period as shown in Figure 5. As a result, the front wheel lift amount becomes relatively smaller (the angle θ4 corresponding to the front wheel lift amount becomes relatively smaller than the angle θ3 in Figure 5), and the value T32 at which the rear wheel torque begins to decrease also becomes relatively smaller than the value T22 in Figure 5. Furthermore, from the viewpoint of simplifying the setting of target values, the target value of the front wheel lift amount when the second mode is selected and the obstacle detection unit 102c recognizes that there are obstacles in the direction of travel of vehicle 1 (other vehicles are obstacles) may be set to be equal to each other. However, in such cases, it may be assumed that the target value of the front wheel lift amount when the second mode is selected and the obstacle determination unit 102c continues to recognize that there are no obstacles in the direction of travel of vehicle 1 (other vehicles are not obstacles) for the entire period is set to be greater than the target value of the front wheel lift amount when the first mode is selected and the obstacle determination unit 102c recognizes that there are obstacles in the direction of travel of vehicle 1 (other vehicles are obstacles). Also, at time t32, the rear wheel speed continues to increase from v31, but the front wheel speed has started to decrease from v31.Next, at time t33, the rear wheel torque becomes T32, and at time t34, the front wheel lift determination unit 102a determines that the front wheel lift has been eliminated, and from time t34 to time t35, the front wheel speed substantially matches the rear wheel speed v33. Next, at time t36, the required torque begins to decrease from T33 due to the driver's closing accelerator operation. Next, at time t37, as the required torque becomes T32 and matches the rear wheel torque which was substantially maintained at T32, the rear wheel torque begins to follow the required torque, and at time t38, the driver's closing accelerator operation begins to be maintained at a constant opening, and the required torque and rear wheel torque begin to be maintained at substantially constant values ​​of T34.

[0036] As is clear from the above description, in the first aspect of the vehicle driving support system S of this embodiment, when the control unit 104 recognizes an object located in the direction of travel of the saddle-type vehicle 1 as an obstacle, it performs a suppression process to suppress the amount of front wheel lift so that the amount of front wheel lift is smaller than when the object is not recognized as an obstacle. Therefore, it is possible to realize a vehicle driving support system S that ensures the freedom of driving of the saddle-type vehicle 1 equipped with the advanced driving support system S with the external environment detection device 200, while enabling the external environment detection device 200 to continue to detect objects that may become obstacles.

[0037] Furthermore, in the second aspect of the vehicle driving support system S of this embodiment, in addition to the first aspect, a storage unit M is further provided which stores data having multiple modes that define target values ​​for the front wheel lift amount for each of the multiple modes. The control unit 104 obtains a target value by referring to the data based on the mode selected from the multiple modes and controls the front wheel lift amount to approach the target value, so that the driver's intention to drive can be appropriately reflected in the driving state.

[0038] Furthermore, in the third aspect of the vehicle driving support system S of this embodiment, in addition to the second aspect, when the control unit 104 recognizes that an object located in the direction of travel of the saddle-type vehicle 1 is an obstacle, it performs suppression processing with a relatively smaller target value compared to when the object is not recognized as an obstacle, thereby enabling more appropriate control of the front wheel lift amount.

[0039] Furthermore, in the fourth aspect of the vehicle driving support system S of this embodiment, in addition to the third aspect, when the control unit 104 recognizes that an object located in the direction of travel of the saddle-type vehicle 1 is an obstacle, it switches from a first mode, which is the mode before the object located in the direction of travel of the saddle-type vehicle 1 is recognized as an obstacle, to a second mode, which defines a target value that is relatively smaller than the target value defined in the first mode. As a result, the amount of front wheel lift can be controlled more appropriately and reliably.

[0040] Furthermore, in the fifth aspect of the vehicle driving support system S in this embodiment, in addition to any of the second to fourth aspects, each of the multiple modes can be selected by the driver of the saddle-type vehicle 1, thereby appropriately reflecting the driver's intentions in the driving state.

[0041] Furthermore, in the sixth phase of the vehicle driving support system S in this embodiment, in addition to any of the second to fifth phases, a front wheel lift amount calculation unit 102b is further provided to calculate an estimated value of the front wheel lift amount, and the control unit 104 performs feedback control to bring this estimated value closer to the target value, thereby enabling more appropriate control of the front wheel lift amount.

[0042] Furthermore, in the seventh phase of the vehicle driving support system S of this embodiment, in addition to the sixth phase, a front wheel lift determination unit 102a is further provided to determine when front wheel lift begins to occur. The front wheel lift amount calculation unit 102b calculates an estimated value by integrating the pitch angular velocity of the saddle-type vehicle 1 from the time when the front wheel lift determination unit 102a determines that front wheel lift has begun to occur. Therefore, it is possible to more appropriately determine when front wheel lift has begun to occur and to calculate an estimated value of the front wheel lift amount more appropriately.

[0043] Furthermore, in an eighth aspect of the vehicle driving support system S according to the present embodiment, in addition to any one of the first to seventh aspects, the system further comprises a front wheel lift determination unit 102a configured to determine that a front wheel lift is starting to occur, wherein the control unit 104 executes the suppression process when an object located in the traveling direction of the straddle-type vehicle 1 is recognized as the obstacle at a time point when the front wheel lift determination unit 102a determines that the front wheel lift has started to occur, whereby the front wheel lift amount can be more appropriately controlled.

[0044] Furthermore, in a ninth aspect of the vehicle driving support system S according to the present embodiment, in addition to the eighth aspect, the front wheel lift determination unit 102a determines that the front wheel lift has started to occur when the vertically upward acceleration of the vehicle body 10 of the straddle-type vehicle 1 shows an increasing trend, whereby the occurrence of the front wheel lift can be more appropriately determined.

[0045] Furthermore, in a tenth aspect of the vehicle driving support system S according to the present embodiment, in addition to the ninth aspect, the front wheel lift determination unit 102a determines that the front wheel lift has started to occur when a value corresponding to a difference or a ratio between the rotational speeds of the front wheel 32 and the rear wheel 42 becomes equal to or greater than a predetermined value, whereby the occurrence of the front wheel lift can be more appropriately determined.

[0046] Furthermore, in an eleventh aspect of the vehicle driving support system S according to the present embodiment, in addition to any one of the first to tenth aspects, the control unit 104 reduces an amount of change per unit time of the rotational speed of the rear wheel 42 in the suppression process, whereby the front wheel lift amount can be more appropriately controlled.

[0047] Furthermore, in a twelfth aspect of the vehicle driving support system S according to the present embodiment, in addition to the eleventh aspect, the control unit 104 adjusts the driving force of the rear wheel by adjusting an output of a driving source 20 of the straddle-type vehicle 1 including at least one of an internal combustion engine and an electric motor, whereby the front wheel lift amount can be more appropriately and reliably controlled.

[0048] Furthermore, in a thirteenth aspect of the vehicle driving support system S of the present embodiment, in addition to the eleventh or twelfth aspect, the control unit 104 adjusts the braking force of the rear wheel 42 by adjusting the brake pressure of the brake mechanism of the straddle-type vehicle 1, thereby adjusting the driving force of the rear wheel 42. Therefore, the front wheel lift amount can be controlled more appropriately and reliably.

[0049] It should be noted that the present invention is not limited to the above-described embodiment with respect to the type, shape, arrangement, number, etc. of members, and it goes without saying that appropriate changes can be made without departing from the gist of the invention, such as appropriately replacing constituent elements with those exhibiting equivalent functions and effects.

[0050] As described above, the present invention can provide a vehicle driving support system that enables an external world detection device to continue detecting obstacles while ensuring the degree of freedom in driving of a straddle-type vehicle equipped with an advanced driving support system including the external world detection device, and is expected to be widely applicable to straddle-type vehicles due to its general and universal properties.

[0051] S...Driving support system 1...Vehicle 10...Frame member 20...Drive source 22...Spark plug 24...Injector 26...Throttle valve 30...Steering / front suspension mechanism 32...Front wheel 32a...Axle 34...Telescopic front fork 36...Steering stem 38...Handlebar 38a...Accelerator grip 40...Rear suspension mechanism 42...Rear wheel 42a...Axle 44...Swing arm 46...Rear spring damper unit 100...Electronic control unit 102...Processing unit 102a...Front wheel lift determination unit 102b...Front wheel lift amount calculation unit 102c...Obstacle determination unit 104...Control unit 141...Crank sensor 142...Accelerator position sensor 143...Throttle position sensor 144...Driving mode selection member 145...Front wheel speed sensor 146...Rear wheel speed sensor 147...Front wheel stroke sensor 148...Rear wheel stroke sensor 149...IMU 200...External world detection device FB...Front brake RB...Rear brake M...Storage unit

Claims

1. A vehicle driving support system mounted on a saddle-type vehicle having a rear wheel which is a drive wheel and a front wheel which is a driven wheel, and comprising a control unit which controls the amount of front wheel lift, which indicates the degree to which the front wheel moves in a direction that lifts off the road surface by adjusting the driving force of the rear wheel or the braking force of the rear wheel, wherein the control unit executes a suppression process to suppress the amount of front wheel lift so that the amount of front wheel lift is smaller than when the object located in the direction of travel of the saddle-type vehicle is recognized as an obstacle.

2. The vehicle driving support system according to claim 1, further comprising a storage unit that pre-stores data having the multiple modes for which a target value of the front wheel lift amount is defined for each of the multiple modes, wherein the control unit obtains the target value by referring to the data based on a mode selected from the multiple modes, and controls the front wheel lift amount to approach the target value.

3. The vehicle driving support system according to claim 2, wherein when the control unit recognizes the object as an obstacle, it performs the suppression process with a target value that is relatively smaller than when the object is not recognized as an obstacle.

4. The vehicle driving support system according to claim 3, wherein when the control unit recognizes the object as an obstacle, it switches from a first mode, which is the mode before the object is recognized as an obstacle, to a second mode, which defines a target value that is relatively smaller than the target value defined in the first mode.

5. The vehicle driving assistance system according to claim 2, wherein each of the plurality of embodiments is selectable by the driver's operation.

6. The vehicle driving support system according to claim 2, further comprising a front wheel lift amount calculation unit that calculates an estimated value of the front wheel lift amount, wherein the control unit performs feedback control to bring the estimated value closer to the target value.

7. The vehicle driving support system according to claim 6, further comprising a front wheel lift determination unit that determines whether or not front wheel lift has begun, wherein the front wheel lift amount calculation unit calculates the estimated value by integrating the pitch angular velocity of the saddle-type vehicle from the time the front wheel lift determination unit determines that front wheel lift has begun.

8. The vehicle driving support system according to claim 1, further comprising a front wheel lift determination unit for determining the occurrence of the front wheel lift, wherein the control unit executes the suppression process when the object is recognized as the obstacle at the time the front wheel lift determination unit determines that the front wheel lift has begun to occur. 9.8 The vehicle driving support system according to claim 8, wherein the front wheel lift determination unit determines that the front wheel lift has begun when the vertical upward acceleration of the vehicle body of the saddle-type vehicle shows an increasing trend.

10. The vehicle driving support system according to claim 9, wherein the front wheel lift determination unit determines that front wheel lift has begun when a value corresponding to the difference or ratio of rotational speeds between the front wheel and the rear wheel exceeds a predetermined value.

11. The vehicle driving support system according to claim 1, wherein the control unit reduces the amount of change per unit time of the rotational speed of the rear wheels in the suppression process, thereby reducing the amount of front wheel lift.

12. The vehicle driving assistance system according to claim 11, wherein the control unit adjusts the output of the drive source of the saddle-type vehicle, which includes at least one internal combustion engine and an electric motor, thereby adjusting the driving force of the rear wheels.

13. The driving assistance system according to claim 1, wherein the control unit adjusts the braking force of the rear wheels by adjusting the brake pressure of the brake mechanism of the saddle-type vehicle, thereby adjusting the driving force of the rear wheels.

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