Leaning vehicle

Abstract

Provided is a leaning vehicle that can control the pose of the vehicle body so as to enable turning at low speed and small radius, both when running autonomously without being operated by a rider and when running by being operated by the rider. A control device (9) for a leaning vehicle (1) controls a steering torque application device (12) so that a steering torque is applied to at least one front wheel (3) so as to increase the response of a change in a leaning angle (φ) with respect to a steering angle (δ), the steering torque comprising a steering command torque to which a friction cancellation torque is added. The steering command torque is based on first leaning angle information detected by a leaning angle-related information detection device (6), first steering angle information detected by a steering angle-related information detection device (7), and first wheel speed information detected by a wheel speed-related information detection device (8). The friction cancellation torque is for cancelling a friction torque generated due to friction between the at least one front wheel (3) and the travelling surface.

Description

Lean vehicle

[0001] The present invention relates to a lean vehicle that leans to the right when turning right and leans to the left when turning left.

[0002] Conventionally, there is a technology for controlling the posture of a lean vehicle by controlling the steering force applied to a steering mechanism. For example, in a motorcycle disclosed in Patent Document 1, when a disturbance in the roll direction is detected on the vehicle body, a control device drives a steering actuator to apply a steering force to the steering mechanism in the direction of the increase in roll angle due to the disturbance. This causes the vehicle body to right itself. Also, in the motorcycle disclosed in Patent Document 1, when the rate of increase in roll angle detected by a vehicle body behavior detection means is equal to or greater than a predetermined value and the input to the steering wheel detected by a steering input detection means is less than a predetermined steering input threshold, the control device drives the steering actuator to apply a steering force to the steering mechanism in the direction of the increase in roll angle. In the motorcycle disclosed in Patent Document 1, when the control device determines that the rider's body is slow to follow the increase in the vehicle body roll angle or that the rider's body is not following the increase in the vehicle body roll angle sufficiently, resulting in a large amount of body sway, the control device drives the steering actuator to apply a steering force to the steering mechanism in the direction of the increase in lean angle. In addition, in the videos of Non-Patent Documents 1 and 2, the motorcycle autonomously travels almost straight or turns with a large radius when the rider is not driving or when there is no rider on board.

[0003] Japanese Patent Application Laid-Open No. 2020-158067

[0004] Honda | CES 2017 "Honda Riding Assist" (URL: https: / / www.youtube.com / watch?v=Hw2zoXa0WZ8) [CES 2017] Honda unveils the self-standing motorcycle "Honda Riding Assist" for the first time in the world (URL: https: / / www.youtube.com / watch?v=pp76Y6JSYds)

[0005] A lean vehicle traveling at low speeds can turn with a smaller radius than a lean vehicle traveling at high speeds, and it is necessary to control the vehicle body posture so that the vehicle can turn at low speeds and with a smaller radius.

[0006] An object of the present invention is to provide a lean vehicle that can control the attitude of the vehicle body so that it can turn at a low speed and with a small radius, whether the vehicle is running autonomously without being driven by a rider or when the vehicle is being driven by a rider.

[0007] The present inventors studied the technology of Patent Document 1 to develop a technology for controlling the posture of a lean-angle vehicle so that it can turn at low speeds and with a small turning radius. The inventors considered controlling a lean-angle vehicle autonomously at low speeds without a rider, as described in Non-Patent Documents 1 and 2, by applying a steering force to a steering mechanism to suppress an increase in the lean angle when the lean angle, which is the tilt angle of the vehicle body in the lateral direction relative to the vehicle's vertical direction, increases, as described in Patent Document 1. They then noticed that, while the lean-angle vehicle can travel straight or turn with a large turning radius, when attempting to turn with a small turning radius, the rate at which the lean angle of the vehicle body increases becomes too large, and it may be impossible to apply a steering force sufficient to sufficiently suppress the increase in the lean angle of the vehicle body. The inventors also noticed that, when the rate at which the lean angle of the vehicle body increases is high, applying a large steering force to the steering mechanism can suppress the increase in the lean angle of the vehicle body, but the turning radius increases. Furthermore, the autonomously traveling lean vehicle in the videos of Non-Patent Documents 1 and 2 travels straight or turns with a large radius, but does not turn with a small radius. The inventors of the present application have come up with a technology to control the posture of a lean vehicle so that it can turn at a low speed and with a small radius by focusing on the friction between the steering wheel and the road surface.

[0008] A lean vehicle according to one embodiment of the present invention has the following configuration: a plurality of wheels including at least one front wheel and at least one rear wheel disposed rearward of the at least one front wheel in the longitudinal direction of the vehicle; a body frame that supports the plurality of wheels rotatably about an axle and the at least one front wheel rotatably about a steering axis, and that tilts to the right of the vehicle relative to the vertical direction of the vehicle when turning right and tilts to the left of the vehicle relative to the vertical direction of the vehicle when turning left; a lean angle-related information detection device that detects first lean angle information related to the lean angle, which is the tilt angle of the body frame in the lateral direction of the vehicle relative to the vertical direction of the vehicle; a steering angle-related information detection device that detects first steering angle information related to the steering angle, which is the rotational angle of any one of the front wheels about the steering axis; a wheel speed-related information detection device that detects first wheel speed information related to the wheel speed, which is the rotational speed of any one of the wheels about the axle; and a steering torque detection device that applies a steering torque about the steering axis to the at least one front wheel. a control device configured to control the steering torque applied by the steering torque application device and to control the steering torque applied to the at least one front wheel from the steering torque application device so that the steering angle and the lean angle are adjusted, wherein the control device controls the steering torque application device so that the steering torque applied to the at least one front wheel is the sum of a steering command torque based at least on the first lean angle information detected by the lean angle-related information detection device, the first steering angle information detected by the steering angle-related information detection device, and the first wheel speed information detected by the wheel speed-related information detection device, and a friction cancellation torque for canceling out friction torque generated by friction between the at least one front wheel and a driving surface, so as to increase responsiveness of a change in the lean angle to a change in the steering angle.

[0009] When a lean vehicle is traveling at low speeds, friction torque is the dominant factor in lean angle fluctuations. Furthermore, friction torque, which is the dominant factor in lean angle fluctuations, varies depending on factors such as the friction coefficient of the road surface and the air pressure of at least one front wheel. Therefore, friction torque is prone to change when a lean vehicle is traveling at low speeds. However, it is difficult to directly measure friction torque. In this configuration, the steering angle and roll angle of a lean vehicle are adjusted by controlling the steering torque applied to at least one front wheel from the steering torque application device. Furthermore, to increase the responsiveness of the lean angle change to a change in the steering angle, the steering torque application device is controlled so that a steering command torque is applied to at least one front wheel, the steering command torque being calculated by adding a friction offset torque for offsetting the friction torque generated by friction between at least one front wheel and the road surface to the steering command torque based on the first lean angle information detected by the lean angle-related information detection device, the first steering angle information detected by the steering angle-related information detection device, and the first wheel speed information detected by the wheel speed-related information detection device. As a result, whether the lean vehicle is traveling autonomously at low speeds without being driven by a rider, or the lean vehicle is traveling at low speeds while being driven by a rider, the increase in the lean angle can be suppressed regardless of the magnitude of the friction torque of the lean vehicle, allowing the lean vehicle to turn at a smaller radius. Also, by performing this control when the lean vehicle is traveling with a rider on board, the amount of operation of the handlebars by the rider when turning the lean vehicle at a smaller radius can be suppressed. Therefore, it is easier to turn the lean vehicle at a smaller radius.

[0010] A lean vehicle according to one embodiment of the present invention may have the following configuration: a handlebar section operated by a rider; and a connection section connecting the handlebar section and the at least one front wheel, the connection section being supported by the body frame so that the handlebar section is rotatable about a handlebar axis, the connection section connecting the handlebar section and the at least one front wheel so that when the handlebar section rotates about the handlebar axis, the at least one front wheel rotates about the steering axis, and when the at least one front wheel rotates about the steering axis, the handlebar section rotates about the handlebar axis, and the rotation angle of any one of the at least one front wheels about the steering axis is equal to or greater than the rotation angle of the handlebar section about the handlebar axis.

[0011] In a lean vehicle in which the rotation angle of at least one front wheel about the steering axis is equal to or greater than the rotation angle of the steering wheel about the steering axis of the steering wheel, the rotation angle of the steering wheel when rotating the front wheel by the same rotation angle is smaller than that of a vehicle in which the rotation angle of the front wheel about the steering axis is less than the rotation angle of the steering wheel about the steering axis of the steering wheel. Therefore, even if the change in the rotation angle of the steering wheel about the steering axis is small, the friction torque generated by friction between the front wheel and the road surface when the front wheel rotates about the steering axis in response to the rotation of the steering wheel about the steering axis changes significantly. Therefore, if the steering torque applied to at least one front wheel is not a steering command torque plus a friction offset torque, it is difficult to turn a lean vehicle in a small radius. According to this configuration, the control device controls the application of a steering torque to at least one front wheel that is the sum of the steering command torque and the friction offset torque so as to increase the responsiveness of changes in lean angle to changes in steering angle. As a result, by setting the rotation angle of at least one of the front wheels about the steering axis to be equal to or greater than the rotation angle of the handlebars about the steering axis, even in a lean vehicle in which the friction torque generated by friction between the front wheel and the riding surface changes significantly even with a small change in the rotation angle of the handlebars about the steering axis, the increase in the lean angle is effectively suppressed regardless of the magnitude of the friction torque of the lean vehicle, allowing the lean vehicle to turn at a smaller radius. Furthermore, by performing this control when the lean vehicle is ridden and traveling by a rider, the amount of operation of the handlebars by the rider when turning the lean vehicle at a smaller radius is effectively suppressed. Therefore, it is easy to turn the lean vehicle at a smaller radius.

[0012] A lean vehicle according to one embodiment of the present invention may have the following configuration: a handlebar section operated by a rider; and a connection section connecting the handlebar section to the at least one front wheel, the connection section being supported by the vehicle body frame so that the handlebar section is rotatable around a handlebar axis within a rotation angle range of less than 360°, the connection section connecting the handlebar section to the at least one front wheel such that when the handlebar section rotates around the handlebar axis, the at least one front wheel rotates around the steering axis, and when the at least one front wheel rotates around the steering axis, the handlebar section rotates around the handlebar axis.

[0013] When the range of angles at which at least one front wheel can rotate about its steering axis is the same, a lean vehicle equipped with a handlebar that can rotate within a rotation angle range of less than 360° requires a smaller rotation angle of the handlebar when rotating the front wheel the same rotation angle compared to a vehicle equipped with a handlebar that can rotate within a rotation angle range of 360° or more. Therefore, even if the change in the rotation angle of the handlebar about the steering axis is small, the friction torque generated by friction between the front wheel and the road surface when the front wheel rotates about the steering axis in response to the rotation of the handlebar about the steering axis changes significantly. Therefore, if the steering torque applied to at least one front wheel is not a steering command torque plus a friction offset torque, it is difficult to turn a lean vehicle with a small radius. According to this configuration, the control device controls the application of a steering torque to at least one front wheel that is the sum of the steering command torque and the friction offset torque so as to increase the responsiveness of changes in lean angle to changes in steering angle. As a result, because the handlebars can rotate around the handlebar axis within a rotational angle range of less than 360°, even in a lean vehicle in which the friction torque generated by friction between the front wheel and the riding surface changes significantly even with a small change in the rotational angle of the handlebars around the steering axis, the increase in the lean angle is highly effective in suppressing regardless of the magnitude of the friction torque of the lean vehicle, and the lean vehicle can be turned at a smaller radius. Furthermore, by performing this control when the lean vehicle is ridden and traveling by a rider, the amount of operation of the handlebars by the rider when turning the lean vehicle at a smaller radius is highly effective in suppressing. Therefore, it is easy to turn the lean vehicle at a smaller radius.

[0014] A lean vehicle according to one embodiment of the present invention may have the following configuration: A contact portion, which is a portion of an outer edge of the at least one front wheel in contact with a running surface in a cross section perpendicular to the circumferential direction, is arc-shaped.

[0015] In a lean vehicle in which the contact area of ​​the front wheel, which is the portion of the outer edge of the front wheel in contact with the road surface in a cross section perpendicular to the circumferential direction, is arc-shaped, the contact position of the front wheel with the road surface changes when the lean angle of the lean vehicle changes and the front wheel is steered, causing a change in the road area of ​​the front wheel. Therefore, in a lean vehicle in which the contact area of ​​the front wheel is arc-shaped, the change in the road area of ​​the front wheel is greater than in a vehicle in which the contact area of ​​the front wheel is flat. Furthermore, a change in the road area of ​​the front wheel changes the friction torque. Therefore, in a lean vehicle in which the contact area of ​​the front wheel is arc-shaped, the change in friction torque during driving is more likely to be greater than in a vehicle in which the contact area of ​​the front wheel is flat. With this configuration, in a lean vehicle in which the change in friction torque during driving is more likely to be greater, a steering torque that is the sum of a steering command torque and a friction offset torque is applied to at least one front wheel so as to increase the responsiveness of changes in lean angle to changes in steering angle. This effectively suppresses the increase in the lean angle regardless of the magnitude of the friction torque of the lean vehicle, whether the lean vehicle is traveling autonomously at low speed without being driven by a rider or traveling at low speed while being driven by a rider, and allows the lean vehicle to turn at a smaller radius. Also, by performing this control when the lean vehicle is traveling with a rider on board, it is highly effective in suppressing the amount of operation of the handlebars by the rider when turning the lean vehicle at a smaller radius. Therefore, it is easy to turn the lean vehicle at a smaller radius.

[0016] A lean vehicle according to one embodiment of the present invention may have the following configuration: When the lean vehicle is turning in a manner that alternates between a state in which the at least one front wheel is steered to the right of the vehicle and a state in which the at least one front wheel is steered to the left of the vehicle, the control device controls the steering torque imparting device to impart to the at least one front wheel the steering torque obtained by adding the steering command torque based at least on the first lean angle information detected by the lean angle-related information detecting device, the first steering angle information detected by the steering angle-related information detecting device, and the first wheel speed information detected by the wheel speed-related information detecting device to the friction canceling torque that cancels out the friction torque generated by friction between the at least one front wheel and a driving surface, so as to increase the responsiveness of a change in the lean angle to a change in the steering angle.

[0017] The friction between at least one front wheel and the road surface has hysteresis, and the steering torque required to set the steering angle of at least one front wheel to a certain angle is affected by this hysteresis. Therefore, when a lean vehicle is turning in a direction in which at least one front wheel is alternately steered rightward in the vehicle's left-right direction and leftward in the vehicle's left-right direction, the relationship between the steering angle and the steering torque is significantly different when the at least one front wheel is steered rightward in the vehicle's left-right direction and when the at least one front wheel is steered leftward in the vehicle's left-right direction. Furthermore, when the friction between the at least one front wheel and the road surface differs, the hysteresis also differs. As described above, in this configuration, when at least a lean vehicle is turning in a direction in which at least one front wheel is steered, the steering torque imparting device is controlled so that a steering torque obtained by adding a friction offset torque to a steering command torque is imparted to at least one front wheel, so as to increase the responsiveness of a change in lean angle to a change in steering angle. This effectively suppresses the increase in the lean angle regardless of the magnitude of the friction torque of the lean vehicle, whether the lean vehicle is autonomously traveling to turn at low speeds without being driven by a rider, or whether the lean vehicle is driven by a rider to turn at low speeds, and allows the lean vehicle to turn at a smaller radius. Also, by performing this control when the lean vehicle is being ridden by a rider and turning at low speeds, it is highly effective in suppressing the amount of operation of the handlebars by the rider when turning the lean vehicle at a smaller radius. Therefore, it is easy to turn the lean vehicle at a smaller radius.

[0018] A lean vehicle according to one embodiment of the present invention may have the following configuration: When the vehicle speed of the lean vehicle is at least higher than 0 km / h and equal to or lower than 10 km / h, the control device controls the steering torque application device to apply to the at least one front wheel the steering torque obtained by adding the steering command torque based at least on the first lean angle information detected by the lean angle-related information detection device, the first steering angle information detected by the steering angle-related information detection device, and the first wheel speed information detected by the wheel speed-related information detection device to the friction cancellation torque that cancels out the friction torque generated by friction between the at least one front wheel and a driving surface, so as to increase the responsiveness of a change in the lean angle to a change in the steering angle.

[0019] When a lean vehicle is traveling at a low speed, such as when the vehicle speed is higher than 0 km / h and is equal to or lower than 10 km / h, friction torque is the dominant factor in fluctuations in the lean angle. Therefore, by controlling the steering torque application device so that a steering torque equal to the steering command torque plus a friction offset torque is applied to the front wheels, thereby increasing the responsiveness of changes in the lean angle to changes in the steering angle, the increase in the lean angle can be suppressed regardless of the magnitude of the friction torque of the lean vehicle, allowing the lean vehicle to turn at a smaller radius, whether the lean vehicle is traveling autonomously at low speed without being driven by a rider or traveling at low speed while being driven by a rider. Furthermore, by performing this control when the lean vehicle is traveling driven by a rider, the amount of steering wheel operation by the rider when turning the lean vehicle at a smaller radius can be suppressed. This makes it easier to turn the lean vehicle at a smaller radius.

[0020] A lean-wheel vehicle according to one embodiment of the present invention may have the following configuration: When the lean-wheel vehicle is traveling autonomously without being driven by a rider or when the lean-wheel vehicle is traveling while being driven by a rider, the control device controls the steering torque applying device to apply to the at least one front wheel the steering torque obtained by adding the steering command torque based at least on the first lean angle information detected by the lean angle-related information detecting device, the first steering angle information detected by the steering angle-related information detecting device, and the first wheel speed information detected by the wheel speed-related information detecting device to the friction canceling torque that cancels out the friction torque generated by friction between the at least one front wheel and a driving surface, so as to increase responsiveness of a change in the lean angle to a change in the steering angle.

[0021] With this configuration, when the lean vehicle is traveling autonomously without being driven by a rider, the increase in the lean angle can be suppressed regardless of the magnitude of the friction torque of the lean vehicle, allowing the lean vehicle to turn with a smaller radius. Also, when the lean vehicle is traveling driven by a rider, the increase in the lean angle can be suppressed regardless of the magnitude of the friction torque of the lean vehicle, allowing the lean vehicle to turn with a smaller radius. Also, the amount of handlebar operation by the rider when turning the lean vehicle with a smaller radius can be suppressed. Therefore, it is easy to turn the lean vehicle with a smaller radius.

[0022] A lean vehicle according to one embodiment of the present invention may have the following configuration: When a model is defined as a forward model of the lean vehicle, which receives as input the torque about the steering axis applied to the at least one front wheel and outputs second lean angle information related to the lean angle, second steering angle information related to the steering angle, and second wheel speed information related to the wheel speed immediately after the torque is applied to the at least one front wheel, and a model having an input / output relationship inverse to that of the forward model of the lean vehicle is defined as an inverse model of the lean vehicle, the friction offsetting torque is calculated based on the steering torque applied from the steering torque application device to the at least one front wheel. The torque is based on the difference between the steering torque and a torque based on the torque output from the inverse model of the lean vehicle when the second lean angle information obtained from the first lean angle information detected by the lean angle related information detection device immediately after the steering torque is applied, the second steering angle information obtained from the first steering angle information detected by the steering angle related information detection device, and the second wheel speed information obtained from the first wheel speed information detected by the wheel speed related information detection device are input to the inverse model of the lean vehicle.

[0023] When a lean vehicle is traveling at low speed, friction torque is the dominant factor in fluctuations in the lean angle. Therefore, the dominant factor in the difference between the steering torque applied to at least one front wheel from the steering torque application device and the torque output from the inverse model of the lean vehicle is friction torque. In this configuration, the friction offsetting torque is a torque based on the difference between the steering torque applied to at least one front wheel from the steering torque application device and the torque output from the inverse model of the lean vehicle when, immediately after the steering torque is applied, second lean angle information obtained from first lean angle information detected by the lean angle-related information detection device, second steering angle information obtained from the first steering angle information detected by the steering angle-related information detection device, and second wheel speed information obtained from first wheel speed information detected by the wheel speed-related information detection device are input to the inverse model of the lean vehicle. As a result, whether the lean vehicle is traveling autonomously at low speeds without being driven by a rider, or traveling at low speeds while being driven by a rider, the increase in the lean angle can be suppressed regardless of the magnitude of the friction torque of the lean vehicle, allowing the lean vehicle to turn at a smaller radius. Also, by performing this control when the lean vehicle is traveling while being driven by a rider, the amount of operation of the handlebars by the rider when turning the lean vehicle at a smaller radius can be suppressed. Therefore, it is easier to turn the lean vehicle at a smaller radius.

[0024] The vehicle up-down direction in the present invention and the embodiments is the direction perpendicular to the riding surface. More specifically, it is the direction perpendicular to the contact point of the wheels. The riding surface is the road surface on which the lean vehicle rides. The vehicle fore-aft direction in the present invention and the embodiments is the direction fixed to the body frame and is the direction of travel of the lean vehicle when the lean vehicle is traveling straight. The vehicle left-right direction in the present invention and the embodiments is the direction perpendicular to the vehicle fore-aft direction and the vehicle up-down direction. When a rider rides on a lean vehicle, the vehicle left-right direction is the left-right direction from the rider's perspective.

[0025] In the present invention and embodiments, the plurality of wheels including at least one front wheel and at least one rear wheel may include one front wheel and one rear wheel, one front wheel and multiple rear wheels, or multiple front wheels and one rear wheel. In the present invention and embodiments, the lean vehicle may be a two-wheeled vehicle or a three-wheeled vehicle. The lean vehicle may be a motorcycle or a motor tricycle. Motorcycles also include scooters and mopeds. The lean vehicle may be a two-wheeled or three-wheeled bicycle.

[0026] A lean vehicle according to the present invention and the embodiments may have a positive caster angle. In other words, the steering axis may be tilted backward. The caster angle is the angle between the steering axis and the vertical direction of the vehicle, and is considered positive when the steering axis is tilted backward. A lean vehicle according to the present invention and the embodiments may have a positive trail. Trail is the distance between the ground contact point of the front wheels and the intersection of the steering axis and the road surface. In other words, trail is the distance in the front-to-rear direction of the vehicle between the axle of the front wheels and the intersection of the steering axis and the road surface. A state in which the trail is positive is a state in which the ground contact point of the front wheels is located further forward than the intersection of the steering axis and the road surface. A lean vehicle according to the present invention and the embodiments may be configured so that the trail is unchangeable. A lean vehicle according to the present invention and the embodiments may be configured so that the trail is changeable. The trail may be changeable within a range of positive values. The trail may be changeable from a positive value to a negative value.

[0027] The lean vehicle of the present invention and the embodiments may be configured so that the rear wheels are not steerable. The lean vehicle of the present invention and the embodiments may not have a mechanism that can change the lean angle without changing the steering angle of the front wheels. The lean vehicle of the present invention and the embodiments may not have a mechanism that changes the center of gravity of the body frame without changing the steering angle of the front wheels. The lean vehicle of the present invention and the embodiments may or may not have a rider on board when the control device executes the control of the present invention. The lean vehicle of the present invention and the embodiments may be in a state where it is being driven by a rider or not when the control device executes the control of the present invention. Note that the control of the present invention refers to controlling the steering torque applying device so that a steering torque obtained by adding a friction offset torque to a steering command torque is applied to at least one front wheel so as to increase the responsiveness of changes in the lean angle to changes in the steering angle. Note that a state in which the lean vehicle is not being driven by a rider means that the lean vehicle is in an autonomous driving state. The lean vehicle of the present invention and the embodiments may not be capable of autonomous driving. The lean-back vehicle of the present invention and the embodiments may or may not have a handlebar that the rider operates to maintain or change the steering angle. The lean-back vehicle of the present invention and the embodiments may or may not have at least one operator that the rider operates to maintain or change the vehicle speed (e.g., an accelerator operator, a brake operator, bicycle pedals, etc.).

[0028] In the present invention and its embodiments, "supporting a plurality of wheels rotatably about their axles" means supporting a plurality of wheels rotatably about their own axles. In the present invention and its embodiments, when there are a plurality of front wheels, "supporting at least one front wheel rotatably about its steering axis" means supporting a plurality of front wheels rotatably about their own steering axis. In the present invention and its embodiments, a wheel (front wheel or rear wheel) includes a tire and a wheel body that holds the tire.

[0029] In the present invention and the embodiments, the first lean angle information related to the lean angle detected by the lean angle-related information detection device may include at least one of the lean angle, the lean angular velocity which is the time rate of change of the lean angle, and the lean angular acceleration which is the time rate of change of the lean angular velocity. The lean angle may be a so-called roll angle. The lean angle-related information detection device may be, for example, an IMU (Inertial Measurement Unit).

[0030] In the present invention and embodiments, the first steering angle information related to the steering angle detected by the steering angle-related information detection device may include at least one of the steering angle, steering angular velocity, which is the time rate of change of the steering angle, and steering angular acceleration, which is the time rate of change of the steering angular velocity. In the present invention, the steering angle is the rotation angle of any one front wheel about the steering axis. When a lean vehicle is traveling straight, the steering angle is 0. Note that the term "any one front wheel" does not intend to limit the number of front wheels to multiple. A lean vehicle may have only one front wheel. When the lean vehicle has multiple front wheels, the lean vehicle may be configured so that the rotation angles of the multiple front wheels about the steering axis are always the same. When the lean vehicle has multiple front wheels, the lean vehicle may be configured so that the rotation angles of the multiple front wheels about the steering axis can be slightly different. In this case, the rotation angle of any one front wheel about the steering axis is related to the rotation angles of the remaining front wheels about the steering axis. The lean-back vehicle may have two front wheels, and the rotation angle of the handlebar may be between the rotation angles of the two front wheels about their steering axes. In this case, the information related to the steering angle of one of the front wheels detected by the steering angle-related information detection device may be at least one of the rotation angle of the handlebar, the rotation angular velocity of the handlebar, and the rotation angular acceleration of the handlebar. The steering angle-related information detection device may also be a sensor that detects the rotation angle of a steering shaft that supports the front wheels rotatably about their axles and is supported on the vehicle body frame rotatably about the steering axis. The steering angle-related information detection device may include a sensor that detects the rotation angle of a shaft of an electric motor included in the steering torque application device.

[0031] In the present invention and embodiments, the first wheel speed information related to the wheel speed detected by the wheel speed-related information detection device may include at least one of the rotational speed of the front wheels about the axle, the rotational acceleration of the front wheels about the axle, the rotational amount (number of rotations or rotational angle) of the front wheels about the axle, the rotational speed of the rear wheels about the axle, the rotational acceleration of the rear wheels about the axle, the rotational amount of the rear wheels about the axle, the vehicle speed (vehicle speed in the longitudinal direction of the lean vehicle), and the acceleration in the longitudinal direction of the lean vehicle. In the present invention, the wheel speed refers to the rotational angle of any one of the wheels about the axle. The rotational speed of one wheel about the axle is related to the rotational speed of the remaining wheels about the axle. The rotational speed around the axle is the number of rotations or the rotational angle per unit time. The wheel speed-related information detection device may be a sensor provided on the wheel. The wheel speed-related information detection device may be a device that detects information related to the wheel speed of a lean vehicle using a Global Navigation Satellite System (GNSS). The control device may calculate the vehicle speed from the rotational speed of the front wheels about their axles and the steering angle.The control device may calculate the vehicle speed from the rotational speed of the rear wheels about their axles.

[0032] In the present invention and its embodiments, the steering torque imparting device generates a steering torque and imparts the generated steering torque to at least one front wheel. In the present invention and its embodiments, being configured to impart a steering torque about a steering axis to a front wheel means being configured to impart a steering torque to a member that supports the front wheel rotatably about an axle. For example, the steering torque imparting device may be configured to support the front wheel rotatably about an axle and to impart the steering torque to a steering shaft that is supported on the vehicle frame rotatably about the steering axis. When a lean vehicle has multiple front wheels, the values ​​of the steering torque imparted to the multiple front wheels may be the same or different. In the present invention, the term "steering torque" refers to the steering torque imparted to one front wheel by the steering torque imparting device, or a collective term for multiple steering torques imparted to multiple front wheels by the steering torque imparting device. The steering torque imparting device includes a steering actuator that generates the steering torque. The steering actuator included in the steering torque imparting device is, for example, an electric motor or a hydraulic actuator. When a lean vehicle has multiple front wheels, the number of actuators included in the steering torque application device may be one or the same as the number of front wheels. When a lean vehicle has an electric power steering device, an assist motor (electric motor) that assists the steering force input by the rider in the electric power steering device may function as the steering actuator of the steering torque application device of the present invention. The lean vehicle may also have a steer-by-wire system including a steering torque application device. In the present invention and its embodiments, controlling the steering torque applied to at least one front wheel from the steering torque application device so as to adjust the steering angle and lean angle may mean, for example, controlling the steering torque so that the lean vehicle is in a balanced state when the lean vehicle is traveling with zero acceleration and zero steering angular velocity. The balanced state of a lean vehicle refers to a state in which the combination of the values ​​of the lean angle, steering angle, and vehicle speed is a combination of values ​​that indicates the balanced state of the lean vehicle.A combination of values ​​that indicates the equilibrium state of a lean vehicle is a combination of lean angle, steering angle, and vehicle speed such that if the steering angle and vehicle speed are maintained at those values ​​while driving, the lean angle will remain unchanged and maintained at that value.

[0033] In the present invention, the control device may have a friction canceling torque estimation unit that estimates a friction canceling torque, and may control the steering torque application device so that a steering torque obtained by adding the friction canceling torque estimated by the friction canceling torque estimation unit to the steering command torque is applied to at least one front wheel.

[0034] In the present invention and the embodiments, the lean vehicle may include a driving torque imparting device. When the control device controls the steering torque imparting device so that a steering torque obtained by adding a friction offset torque to a steering command torque is imparted to at least one front wheel so as to increase responsiveness of a change in the lean angle to a change in the steering angle, the control device may control the driving torque imparting device based on first lean angle information detected by the lean angle-related information detecting device, first steering angle information detected by the steering angle-related information detecting device, and first wheel speed information detected by the wheel speed-related information detecting device. For example, when the control device controls the steering torque imparting device and the driving torque imparting device based on first lean angle information detected by the lean angle-related information detecting device, first steering angle information detected by the steering angle-related information detecting device, and first wheel speed information detected by the wheel speed-related information detecting device so as to bring the lean vehicle into a balanced state, the control device may control the steering torque imparting device so that a steering torque obtained by adding a friction offset torque to a steering command torque is imparted to at least one front wheel so as to increase the responsiveness of a change in the lean angle to a change in the steering angle. The driving torque imparting device is configured to impart positive and negative driving torque to at least one wheel. The driving torque imparting device generates a driving torque and imparts the generated driving torque to at least one of the at least one front wheel and the at least one rear wheel. "Configured to impart positive and negative driving torque" means that the device is configured to be able to impart positive and negative driving torque to one wheel at different timings. The positive driving torque is a torque that rotates the wheel in a positive direction so that the lean vehicle moves forward. When a negative drive torque is applied to a wheel while it is rotating in a positive direction, the rotation of the wheel in the positive direction slows down. The drive torque applying device may or may not be configured to generate a torque that rotates the wheel in a negative direction as a negative drive torque. The drive torque applying device may include at least one of an engine and an electric motor. The drive torque applying device may include a brake device. A lean vehicle may not have a brake device included in the drive torque applying device, or may have a brake device that is not included in the drive torque applying device.During execution of the control of this case, if the control device does not control the brake device based on the first lean angle information detected by the lean angle related information detection device, the first steering angle information detected by the steering angle related information detection device, and the first wheel speed information detected by the wheel speed related information detection device, the brake device does not need to be included in the driving torque application device.

[0035] In the present invention and embodiments, the expression "the rotation angle of any one of at least one front wheels about its steering axis is equal to or greater than the rotation angle of the handlebar axis about the steering axis" may mean, for example, that in a case where a lean vehicle has one front wheel that can rotate about its steering axis, the rotation angle of this one front wheel about its steering axis is equal to or greater than the rotation angle of the handlebar axis about the steering axis. Also, in the present invention and embodiments, the expression "the rotation angle of any one of at least one front wheels about its steering axis is equal to or greater than the rotation angle of the handlebar axis about the steering axis" may mean that in a case where a lean vehicle has multiple front wheels that can rotatable about a steering axis, the rotation angle of each of these multiple front wheels about its steering axis is equal to or greater than the rotation angle of the handlebar axis about the steering axis. Furthermore, in the present invention and embodiments, the rotation angle of any one of at least one front wheel about its steering axis being equal to or greater than the rotation angle of the handlebar axis about the steering axis of the handle may mean that the lean vehicle has multiple front wheels rotatable about its steering axis, and these multiple front wheels may include a front wheel whose rotation angle about its steering axis is equal to or greater than the rotation angle of the handlebar axis about the steering axis of the handlebar, and a front wheel whose rotation angle about its steering axis is less than the rotation angle of the handlebar axis about the steering axis of the handlebar. In this case, the front wheel whose rotation angle about its steering axis is equal to or greater than the rotation angle of the handlebar axis about the steering axis of the handlebar when the vehicle turns left in the vehicle left-right direction, and the front wheel whose rotation angle about its steering axis is equal to or greater than the rotation angle of the handlebar axis about the steering axis of the handlebar when the lean vehicle turns right in the vehicle left-right direction, may be the same front wheel or different front wheels. Furthermore, in the present invention and embodiments, if the rotation angle of any of the at least one front wheels about the steering axis is equal to or greater than the rotation angle of the handle section about the handle axis, the average value of the rotation angle of the at least one front wheel about the steering axis may be equal to or greater than the rotation angle of the handle section about the handle axis.Furthermore, in the present invention and embodiments, a case where the rotation angle of one of the at least one front wheels about the steering axis is equal to or greater than the rotation angle of the handlebar unit about the steering axis means, for example, that the connection unit does not include a reduction mechanism that reduces the rotation angle of the at least one front wheel relative to the rotation angle of the handlebar unit about the steering axis. The reduction mechanism is, for example, a mechanism that includes either a rack-and-pinion steering gearbox or a ball-nut steering gearbox. Furthermore, in the present invention and embodiments, for example, if the lean-to vehicle is a two-wheeled vehicle and one front wheel is rotatable about the steering axis, the steering axis may coincide with the steering axis. Furthermore, for example, if the lean-to vehicle has two front wheels rotatable about the steering axis, the steering axis may not coincide with the steering axis. If the steering axis does not coincide with the steering axis, the steering axis may be parallel to the steering axis.

[0036] In the present invention and embodiments, the contact portion, which is the portion of the outer edge of the front wheel in a cross section perpendicular to the circumferential direction that comes into contact with the running surface, refers to the portion of the outer edge of the front wheel in a cross section perpendicular to the circumferential direction that may come into contact with the running surface when the vehicle is leaning. For example, the contact portion of the front wheel refers to the tread surface of the tire. In addition, the fact that the contact portion of the front wheel is arc-shaped includes cases where the contact portion of the front wheel is an arc with a constant curvature and a curve that is close to an arc with an inconstant curvature.

[0037] In the present invention, when a lean vehicle is turning in a manner in which at least one front wheel alternates between being steered to the right of the vehicle and being steered to the left of the vehicle, this may be, for example, when the lean vehicle is slaloming or when the lean vehicle is traveling in a figure-eight pattern.

[0038] In the present invention and its embodiments, the forward model of a lean vehicle is a model of a lean vehicle in which the input (control variable) is steering torque and the outputs (detected values) are second lean angle information, second steering angle information, and second wheel speed information. For example, the forward model of a lean vehicle may be expressed by a transfer function G(s). The second lean angle information may include at least one of a lean angle, a lean angular velocity which is a time rate of change of the lean angle, and a lean angular acceleration which is a time rate of change of the lean angular velocity. The second lean angle information may be the same information as the first lean angle information detected by the lean angle-related information detection device. The second lean angle information may be information related to the first lean angle information detected by the lean angle-related information detection device but different from the first lean angle information. The second steering angle information may include at least one of a steering angle, a steering angular velocity which is a time rate of change of the steering angle, and a steering angular acceleration which is a time rate of change of the steering angular velocity. The second steering angle information may be the same as the first steering angle information detected by the steering angle-related information detection device. The second steering angle information may be information related to the first steering angle information detected by the steering angle-related information detection device but different from the first steering angle information. The second wheel speed information may include at least one of the rotational speed of the front wheels about their axles, the rotational acceleration of the front wheels about their axles, the rotational amount (number of rotations or rotation angle) of the front wheels about their axles, the rotational speed of the rear wheels about their axles, the rotational acceleration of the rear wheels about their axles, the rotational amount of the rear wheels about their axles, the vehicle speed (vehicle speed in the longitudinal direction of a lean vehicle), and the acceleration of the lean vehicle in the longitudinal direction of a lean vehicle. The second wheel speed information may be the same as the first wheel speed information detected by the wheel speed-related information detection device. The second wheel speed information may be information related to the first wheel speed information detected by the wheel speed-related information detection device but different from the first wheel speed information. The inverse model of a lean vehicle is a model in which the input / output relationship is reversed from that of the forward model of a lean vehicle. That is, in the inverse model of a lean vehicle, the inputs are the second lean angle information, the second steering angle information, and the second wheel speed information, and the output is the steering torque. When the forward model of a lean vehicle is expressed by a transfer function G(s), the inverse model of a lean vehicle is expressed by the inverse transfer function G －１(s). The control device may also store information about the inverse model of a lean vehicle. In the present invention and its embodiments, the torque based on the torque output from the inverse model of a lean vehicle may be the torque output from the inverse model of a lean vehicle itself, or may be another torque based on the torque output from the inverse model of a lean vehicle. The other torque based on the torque output from the inverse model of a lean vehicle may be, for example, a torque calculated by multiplying the torque output from the inverse model of a lean vehicle by a predetermined coefficient. In the present invention and its embodiments, the friction offsetting torque is a torque based on the difference between the torque based on the torque output from the inverse model of a lean vehicle and the steering torque. The friction offsetting torque may be the difference itself, or may be a torque different from the difference corresponding to the difference. The torque different from the difference may be, for example, a torque calculated by multiplying the difference by a predetermined coefficient.

[0039] Whether the control device controls the steering torque applying device so as to apply to at least one front wheel a steering torque obtained by adding a friction canceling torque for canceling out friction torque generated by friction between at least one front wheel and the road surface to a steering command torque based on first lean angle information detected by the lean angle-related information detecting device, first steering angle information detected by the steering angle-related information detecting device, and first wheel speed information detected by the wheel speed-related information detecting device can be determined, for example, as follows: First, whether the steering command torque is controlled based at least on the first lean angle information detected by the lean angle-related information detecting device, the first steering angle information detected by the steering angle-related information detecting device, and the first wheel speed information detected by the wheel speed-related information detecting device is determined, for example, as follows: A test is performed multiple times in which a lean vehicle is started and accelerated to a target vehicle speed. Test conditions, such as the steering angle before start, the lean angle before start, the target vehicle speed, and the acceleration up to the target vehicle speed, are changed. The test conditions include whether the lean vehicle travels straight or turns during acceleration, as well as the value of the turning radius. Tests using the same test conditions are also conducted multiple times. Note that even if the same test conditions are set, the behavior of the lean vehicle is not necessarily identical. This also applies to the lean vehicle of the present invention. The lower the target vehicle speed and acceleration, the more likely the lean vehicle will behave differently even when the same test conditions are set. In each test, the lean angle, lean angular velocity, lean angular acceleration, steering angle, steering angular velocity, steering angular acceleration, vehicle speed, and acceleration in the longitudinal direction of the lean vehicle are measured. The test results are then examined to determine whether they satisfy the following discrimination conditions A1 to A3. A1: In any two tests, there is a time point at which the steering angle, steering angular velocity, steering angular acceleration, vehicle speed, and acceleration in the longitudinal direction of the lean vehicle are the same, but the lean angle is different, and the steering torque applied immediately after this time point is different. A2: In any two tests, the lean angle, lean angular velocity, lean angular acceleration, vehicle speed, and acceleration in the forward direction of the lean vehicle are the same, but there is a point in time when the steering angle is different, and the steering torque applied immediately after this point is different.A3: In any two tests, there is a time point at which the lean angle, lean angular velocity, lean angular acceleration, steering angle, steering angular velocity, and steering angular acceleration are the same, the lean angle is greater than 0, and the vehicle speeds are different, and the steering torques applied immediately after this time point are different. If there is a test result in which the steering torque satisfies the determination conditions A1 to A3, it can be determined that the steering command torque is controlled based at least on the first lean angle information detected by the lean angle-related information detection device, the first steering angle information detected by the steering angle-related information detection device, and the first wheel speed information detected by the wheel speed-related information detection device. If it can be estimated that the steering command torque is a torque based at least on the first lean angle information detected by the lean angle-related information detection device, the first steering angle information detected by the steering angle-related information detection device, and the first wheel speed information detected by the wheel speed-related information detection device, for example, a first running test and a second running test are performed as follows to determine whether the steering torque applying device is controlled so that a steering torque obtained by adding a friction offset torque to the steering command torque is applied to at least one front wheel. In the first test running, the lean vehicle is run on a first running surface while maintaining the lean angle, steering angle, and vehicle speed. From this state, the lean vehicle is caused to turn by alternately applying an external force to the steering shaft to steer the front wheels to the right of the vehicle and an external force to steer the front wheels to the left of the vehicle, thereby changing the steering angle. When the lean vehicle is caused to turn, the lean vehicle may be run in a slalom or a figure-eight pattern. The same applies to the turning runs in the second to twelfth test runnings described below. In the second test run, the lean vehicle is run on a second running surface having a different coefficient of friction from the first running surface while maintaining the lean angle, steering angle, and vehicle speed. From this state, the same external force as in the first test run is applied to the steering shaft to change the steering angle, causing the lean vehicle to turn and run. In the first and second running tests, the lean angle, steering angle, and vehicle speed before the application of the external force are the same. Here, the friction coefficient of the running surface on which the lean vehicle runs is made different between the first and second running tests, thereby making the friction torque different.If there is no significant difference between the first and second running tests in the way the lean angle, steering angle, and vehicle speed change after the external force is applied, it can be estimated that the steering torque applied by the steering torque application device is a steering torque obtained by adding a friction offsetting torque to the steering command torque. If there is a significant difference between the first and second running tests in the way the information related to the lean angle, the information related to the steering angle, and the information related to the wheel speed change after the external force is applied, it can be estimated that the steering torque applied by the steering torque application device is a torque corresponding to the steering command torque to which no torque for offsetting the friction torque has been added. Alternatively, for example, by performing a third and a fourth running test as follows, it can be determined whether the steering torque application device is controlled so that a steering torque obtained by adding a friction offsetting torque to the steering command torque is applied to at least one front wheel. In the third running test, the lean vehicle is run with the air pressure of the front and rear tires set to a predetermined pressure, while maintaining the lean angle, steering angle, and vehicle speed. From this state, an external force that steers the front wheels to the right of the vehicle and an external force that steers the front wheels to the left of the vehicle are alternately applied to the steering shaft to change the steering angle, causing the lean vehicle to turn around. In the fourth running test, the lean vehicle is run with the air pressure of the front and rear wheels set to a different pressure from that in the third running test, while maintaining the lean angle, steering angle, and vehicle speed. From this state, the same external force as in the third running test is applied to the steering shaft to change the steering angle, causing the lean vehicle to turn around. In the third and fourth running tests, the lean angle, steering angle, and vehicle speed before the application of the external force are the same. Here, the friction torque is made different between the third and fourth running tests by changing the air pressure of the front tires. If there is no significant difference between the third and fourth driving tests in the way the lean angle, steering angle, and vehicle speed change after the external force is applied, it can be estimated that the steering torque applied by the steering torque application device is a steering torque obtained by adding a friction offset torque to the steering command torque.If there is a significant difference between the third and fourth running tests in the way the lean angle, steering angle, and wheel speed change after the application of the external force, it can be estimated that the steering torque applied by the steering torque application device is a torque corresponding to the steering command torque to which no torque for offsetting the friction torque has been applied. Alternatively, for example, by conducting the fifth and sixth running tests as described below, it may be determined whether the steering torque application device is controlled so that a steering torque obtained by adding the friction offset torque to the steering command torque is applied to at least one front wheel. In the fifth running test, a lean vehicle is run with front wheels having a first width attached while maintaining the lean angle, steering angle, and vehicle speed. From this state, the lean vehicle is caused to turn around and run by alternately applying an external force to the steering shaft to steer the front wheels to the right of the vehicle and an external force to steer the front wheels to the left of the vehicle, thereby changing the steering angle. In the sixth running test, the lean vehicle is run with front wheels having a second width different from the first width attached, while maintaining the lean angle, steering angle, and vehicle speed. From this state, the same external force as in the fifth running test is applied to the steering shaft to change the steering angle, causing the lean vehicle to turn. In the fifth and sixth running tests, the lean angle, steering angle, and vehicle speed before the application of the external force are the same. Here, the friction torque is made different between the fifth and sixth running tests by changing the width of the front wheels. If there is no significant difference in the way the lean angle, steering angle, and vehicle speed change after the application of the external force between the fifth and sixth running tests, it can be estimated that the steering torque applied by the steering torque application device is a steering torque obtained by adding a friction offset torque to the steering command torque. If there is a significant difference between the fifth and sixth driving tests in the way the lean angle, steering angle, and wheel speed change after the above-mentioned external force is applied, it can be estimated that the steering torque applied by the steering torque application device is a torque corresponding to the steering command torque to which no torque to offset the friction torque has been applied.Alternatively, for example, by conducting the seventh and eighth running tests as follows, it may be determined whether the steering torque applying device is controlled so that a steering torque obtained by adding a friction offset torque to a steering command torque is applied to at least one front wheel. In the seventh running test, a rider is made to drive a lean vehicle, causing the lean vehicle to turn around on a first running surface. In the eighth test running, a rider is made to drive the lean vehicle, causing the lean vehicle to turn around on a second running surface having a different coefficient of friction from the first running surface. The running trajectory and vehicle speed of the lean vehicle are made approximately the same in the seventh and eighth running tests. Here, the friction torque is made different between the seventh and eighth running tests by making the friction coefficient of the running surface on which the lean vehicle travels different. If there is no significant difference in the steering torque applied by the rider to the handlebars when the lean vehicle is traveling between the seventh and eighth traveling tests, it can be estimated that the steering torque applied by the steering torque application device is a steering torque obtained by adding a friction offset torque to the steering command torque. If there is a significant difference in the steering torque applied by the rider to the handlebars when the lean vehicle is traveling between the seventh and eighth traveling tests, it can be estimated that the steering torque applied by the steering torque application device is a torque corresponding to the steering command torque to which no torque to offset the friction torque has been added. Alternatively, for example, the ninth and tenth traveling tests may be performed as follows to determine whether the steering torque application device is controlled so that a steering torque obtained by adding a friction offset torque to the steering command torque is applied to at least one front wheel. In the ninth traveling test, the air pressure of the front and rear tires is set to a predetermined pressure, and the rider drives the lean vehicle to perform turning movements. In the tenth test run, the front and rear wheel air pressures of the lean vehicle were set to different pressures than in the ninth test run, and the rider was made to drive the lean vehicle and turn the vehicle around. The running path and vehicle speed of the lean vehicle were made approximately the same in the ninth and tenth tests. Here, by changing the front wheel air pressure between the ninth and tenth tests, the friction torque was made different.If there is no significant difference in the steering torque applied by the rider to the handlebars when the lean vehicle is traveling between the ninth and tenth traveling tests, it can be estimated that the steering torque applied by the steering torque application device is a steering torque obtained by adding a friction offset torque to the steering command torque. If there is a significant difference in the steering torque applied by the rider to the handlebars when the lean vehicle is traveling between the ninth and tenth traveling tests, it can be estimated that the steering torque applied by the steering torque application device is a torque corresponding to the steering command torque to which no torque for offsetting the friction torque has been added. Alternatively, for example, by conducting the eleventh and twelfth traveling tests as described below, it can be determined whether the steering torque application device is controlled so that a steering torque obtained by adding a friction offset torque to the steering command torque is applied to at least one front wheel. In the eleventh traveling test, the lean vehicle is equipped with a front wheel having a first width, and the rider is made to drive the lean vehicle to perform turning movements. In the twelfth running test, the lean vehicle is fitted with a front wheel having a second width different from the first width, and the rider drives the lean vehicle to perform turning movements. The running trajectory and vehicle speed of the lean vehicle are substantially the same in the eleventh and twelfth running tests. The front wheel width is made different between the eleventh and twelfth running tests to make the friction torque different. If there is no significant difference in the steering torque applied by the rider to the handlebars when the lean vehicle is running between the eleventh and twelfth running tests, it can be estimated that the steering torque applied by the steering torque application device is a steering torque obtained by adding a friction offset torque to the steering command torque. If there is a significant difference in the steering torque applied by the rider to the handlebars when the lean vehicle is running between the eleventh and twelfth running tests, it can be estimated that the steering torque applied by the steering torque application device is a torque corresponding to the steering command torque to which no torque for offsetting the friction torque has been added.

[0040] In the present invention and the embodiments, the rotation is not limited to a rotation of 360° or more, but also includes a rotation of less than 360°.

[0041] In the present invention and the embodiments, "control based on A" does not mean that the information used for control is limited to only A. "Control based on A" includes cases where control is based on A and information other than A.

[0042] In the present invention and the embodiments, "at least one (one) of a plurality of options" includes all possible combinations of the plurality of options. "At least one (one) of the plurality of options" may be any one of the plurality of options, or may be all of the plurality of options. For example, "at least one of A, B, and C" may be only A, only B, only C, A and B, A and C, B and C, or A, B, and C.

[0043] In the claims, if the number of a certain element is not clearly specified and is expressed in the singular when translated into English, the present invention may have a plurality of this element, or the present invention may have only one of this element.

[0044] In the present invention and embodiments, the words including, comprising, having, and their derivatives are used herein to encompass additional items in addition to the listed items and equivalents thereof.

[0045] In the present invention and the embodiments, the terms "mounted, connected, coupled, and supported" are used broadly. Specifically, they include not only direct mounting, connection, coupling, and support, but also indirect mounting, connection, coupling, and support. Furthermore, connected and coupled are not limited to physical or mechanical connections / couplings. They also include direct or indirect electrical connections / couplings.

[0046] Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification and claims have the same meaning as commonly understood by those skilled in the art to which this invention belongs. Terms, such as those defined in commonly used dictionaries, should be interpreted to have a meaning consistent with the meaning in the context of the relevant technology and this disclosure, and should not be interpreted in an idealized or overly formal sense.

[0047] In the present invention and the embodiments, the term "preferable" is non-exclusive. "Preferable" means "preferably, but not limited to." In this specification, a configuration described as "preferable" at least achieves the above-mentioned effect obtained by the configuration of claim 1. In addition, in this specification, the term "may" is non-exclusive. "may" means "may, but not limited to." In this specification, a configuration described as "may" at least achieves the above-mentioned effect obtained by the configuration of claim 1.

[0048] Before describing embodiments of the present invention in detail, it is to be understood that the invention is not limited to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present invention is capable of embodiments other than those described below. The present invention is also capable of embodiments incorporating various variations of the embodiments described below.

[0049] According to the lean vehicle of the present invention, whether the lean vehicle is traveling autonomously at low speeds without being driven by a rider or traveling at low speeds while being driven by a rider, the increase in the lean angle can be suppressed regardless of the magnitude of the friction torque of the lean vehicle, allowing the lean vehicle to turn at a smaller radius. Furthermore, by performing this control when the lean vehicle is traveling with a rider, the amount of operation of the handlebars by the rider when turning the lean vehicle at a smaller radius can be suppressed. Therefore, it is easier to turn the lean vehicle at a smaller radius.

[0050] 1A and 1B are diagrams illustrating the configuration of a lean vehicle according to a first embodiment of the present invention, a process for controlling a steering torque application device by a control device, and torque applied to at least one front wheel. (a) is a diagram illustrating the configuration of a lean vehicle according to a second embodiment of the present invention as viewed from the front, and (b) is a diagram illustrating the configuration of a lean vehicle according to the second embodiment of the present invention as viewed from above. (a) is a diagram illustrating the contact position of a front wheel with a road surface when the lean angle is 0 according to a third embodiment of the present invention, and (b) is a diagram illustrating the contact position of a front wheel with a road surface when the lean angle changes from 0 according to the third embodiment of the present invention. (a) is a diagram showing an example of the relationship between steering angle and steering torque when a lean vehicle is caused to turn in a fourth embodiment of the present invention, (b) is a diagram illustrating slalom running as a turning running in the fourth embodiment of the present invention, and (c) is a diagram illustrating figure-eight running as a turning running in the fourth embodiment of the present invention. 10A is a block diagram illustrating torque applied to at least one front wheel in a lean vehicle according to a fifth embodiment of the present invention, and FIG. 10B is a block diagram illustrating torque applied to at least one front wheel in a lean vehicle according to a modified example of the fifth embodiment of the present invention. 10C is a block diagram illustrating torque applied to at least one front wheel in a lean vehicle according to a sixth embodiment of the present invention.

[0051] <Definition of directions> In the diagram, U indicates the vehicle upward direction for a lean vehicle, D indicates the vehicle downward direction for a lean vehicle, L indicates the vehicle left direction for a lean vehicle, R indicates the vehicle right direction for a lean vehicle, F indicates the vehicle forward direction for a lean vehicle, and Re indicates the vehicle backward direction for a lean vehicle.

[0052] First Embodiment A first embodiment of the present invention will be described below with reference to FIG. 1 . A lean vehicle 1 of the first embodiment includes a plurality of wheels 2, a vehicle body frame 5, a lean angle-related information detection device 6, a steering angle-related information detection device 7, a wheel speed-related information detection device 8, a steering torque application device 12, and a control device 9. The plurality of wheels 2 include at least one front wheel 3 and at least one rear wheel 4. The at least one rear wheel 4 is disposed rearward of the at least one front wheel 3 in the longitudinal direction of the vehicle. The lean vehicle 1 shown in FIG. 1 is an example of the lean vehicle 1 of this embodiment. Although the lean vehicle 1 shown in FIG. 1 is a motorcycle, the lean vehicle 1 of the first embodiment is not limited to motorcycles. The vehicle body frame 5 supports the plurality of wheels 2 rotatably about an axle line X1 and supports the at least one front wheel 3 rotatably about a steering axis X2. The body frame 5 tilts to the right relative to the vehicle vertical direction when turning right, and tilts to the left relative to the vehicle vertical direction when turning left. The lean angle-related information detection device 6 detects first lean angle information related to the lean angle φ, which is the tilt angle of the body frame 5 in the left-right direction relative to the vehicle vertical direction. The steering angle-related information detection device 7 detects first steering angle information related to the steering angle δ, which is the rotation angle of any one front wheel 3 about the steering axis X2. The wheel speed-related information detection device 8 detects first wheel speed information related to the wheel speed S, which is the rotation speed of any one wheel 2 about the axis X1. The steering torque application device 12 is configured to apply a steering torque about the steering axis X2 to at least one front wheel 3. Note that the lean vehicle 1 may or may not be equipped with a driving torque application device configured to apply a driving torque to at least one front wheel 3 and / or at least one rear wheel 4.

[0053] The control device 9 is configured to control the steering torque applied by the steering torque application device 12. The control device 9 controls the steering torque applied from the steering torque application device 12 to at least one front wheel 3 so as to adjust the steering angle δ and the lean angle φ. At this time, the control device 9 controls the steering torque application device 12 to apply to at least one front wheel 3 a steering torque obtained by adding a steering command torque based at least on the first lean angle information detected by the lean angle-related information detection device 6, the first steering angle information detected by the steering angle-related information detection device 7, and the first wheel speed information detected by the wheel speed-related information detection device 8 to a friction cancellation torque for canceling out friction torque generated by friction between the at least one front wheel 3 and the traveling surface G, so as to increase the responsiveness of a change in the lean angle φ to a change in the steering angle δ. In order to control the steering torque application device 12 as described above, the control device 9 performs processing according to the flowchart shown in FIG. 1 . More specifically, in step S1, the control device 9 determines the steering command torque T1 based on the first lean angle information, the first steering angle information, and the first wheel speed information. Subsequently, in step S2, the control device 9 estimates the friction canceling torque T2. The method for estimating the friction canceling torque T2 in step S2 is not particularly limited. For example, the control device 9 estimates the friction canceling torque T2 based at least on the steering torque T3 immediately before the steering torque application device 12 applied to at least one front wheel 3, and the first lean angle information, the first steering angle information, and the first wheel speed information immediately after the application of the steering torque T3. Subsequently, in step S3, the control device 9 calculates the steering torque T3 and instructs the steering torque application device 12 to apply the calculated steering torque T3 to at least one front wheel 3. The steering torque T3 is the sum of the steering command torque T1 determined in step S1 and the friction canceling torque T2 estimated in step S2. Based on the command, the steering torque applying device 12 applies a steering torque T3 to at least one of the front wheels 3. Thereafter, the control device 9 repeatedly performs the processes of steps S1 to S3.In FIG. 1, the control device 9 performs step S2 after step S1, but step S1 may be performed after step S2, or step S1 and step S2 may be performed in parallel.

[0054] Next, in the first embodiment, the torque about the steering axis X2 applied to at least one front wheel 3 when the control device 9 controls the steering torque application device 12 as described above will be described using the block diagram of FIG. 1 . The steering command torque determiner 21 in the block diagram of FIG. 1 determines the steering command torque T1 in accordance with at least the detected information y. The detected information y refers to information related to the lean angle φ obtained from the first lean angle information, an information value related to the steering angle δ obtained from the first steering angle information, and information related to the wheel speed S obtained from the first wheel speed information. The information related to the lean angle φ obtained from the first lean angle information may be the first lean angle information itself detected by the lean angle-related information detection device 6, or may be information obtained from the first lean angle information that is different from the first lean angle information. For example, the first lean angle information may be the lean angular velocity, and the information related to the lean angle φ obtained from the first lean angle information may be the lean angle φ. The information related to the steering angle δ obtained from the first steering angle information may be the first steering angle information detected by the steering angle-related information detection device 7, or may be information obtained from the first steering angle information, separate from the first steering angle information. The information related to the wheel speed S obtained from the first wheel speed information may be the first wheel speed information detected by the wheel speed-related information detection device 8, or may be information obtained from the first wheel speed information, separate from the first wheel speed information. That is, the steering command torque determiner 21 corresponds to the process of determining the steering command torque T1 in step S1. The friction offsetting torque estimator 22 in the block diagram of FIG. 1 models the process of estimating the friction offsetting torque T2 in step S2, and outputs the friction offsetting torque T2. The plant 23 in the block diagram of FIG. 1 receives the torque about the steering axis X2 applied to at least one front wheel 3 as an input, and outputs detection information y immediately after the torque is applied to at least one front wheel 3. The plant 23 corresponds to the situation in which, in a lean vehicle 1, torque is applied to at least one front wheel 3 around the steering axis X2, and first lean angle information, first steering angle information, and first wheel speed information are detected by the detection devices 6 to 8.As shown in the block diagram of FIG. 1 , the steering torque T3 applied from the steering torque application device 12 to at least one front wheel 3 is the sum of the steering command torque T1 calculated by the steering command torque determination unit 21 and the friction canceling torque T2 estimated by the friction canceling torque estimation unit 22. Then, an applied torque T5, which is the sum of the steering torque T3 and a disturbance torque T4, is applied to at least one front wheel 3 (input to the plant 23). Here, the disturbance torque T4 includes friction torque caused by friction between the at least one front wheel 3 and the traveling surface G. Furthermore, when the lean vehicle 1 is traveling at low speeds, the above-mentioned friction torque is dominant in the disturbance torque T4. Therefore, in the lean vehicle 1 of the first embodiment, while a friction torque is applied to at least one front wheel 3, the steering torque application device 12 applies a friction torque steering torque T3, which is the sum of the steering command torque T1 and the friction canceling torque T2, to at least one front wheel 3. As a result, in the lean vehicle 1, the increase in the lean angle φ can be suppressed regardless of the magnitude of the friction torque, and the lean vehicle 1 can be turned with a smaller radius.

[0055] The control device 9 of the first embodiment may control the steering torque imparting device 12 as described above at least when the vehicle speed of the lean vehicle 1 is higher than 0 km / h and equal to or lower than 10 km / h. The control device 9 of the first embodiment may control the steering torque imparting device 12 as described above only when the vehicle speed is equal to or lower than a predetermined vehicle speed. The predetermined vehicle speed is equal to or higher than 10 km / h. The control device 9 of the first embodiment may control the steering torque imparting device 12 as described above over the entire vehicle speed range of the lean vehicle 1.

[0056] In Figure 1, the contact portion, which is the portion of the outer edge of at least one front wheel 3 that comes into contact with the running surface in a cross section perpendicular to the circumferential direction, is arc-shaped, but the contact portion of at least one front wheel 3 may also be flat.

[0057] Furthermore, in the first embodiment, when the lean vehicle 1 is traveling autonomously without being driven by a rider, as described above, the control device 9 may control the steering torque applying device 12 so that the steering torque T3 obtained by adding the friction offset torque T2 to the steering command torque T1 is applied to at least one front wheel 3 so as to increase the responsiveness of changes in the lean angle φ to changes in the steering angle δ. In this case, the lean vehicle 1 may be provided with a switch that switches whether or not the lean vehicle 1 is traveling autonomously.

[0058] Furthermore, in the first embodiment, when the lean vehicle 1 is driven by a rider, the control device 9 may control the steering torque applying device 12 so that, as described above, a steering torque T3 obtained by adding the friction offset torque T2 to the steering command torque T1 is applied to at least one front wheel 3 so as to increase the responsiveness of changes in the lean angle φ to changes in the steering angle δ. In this case, for example, the lean vehicle 1 may be provided with a switch that switches whether or not the lean vehicle 1 is allowed to travel autonomously. The control device 9 may then detect that the lean vehicle 1 is being driven by a rider based on the lean vehicle 1 traveling with this switch turned off. Note that the lean vehicle 1 of the first embodiment may not have such a switch and may not be capable of autonomous travel.

[0059] Second Embodiment A lean vehicle 1 according to a second embodiment of the present invention will be described below with reference to FIGS. 2( a) and 2(b). The lean vehicle 1 according to the second embodiment has all of the features of the lean vehicle 1 according to the first embodiment. The lean vehicle 1 according to the second embodiment also includes a handlebar unit 29 and a connecting unit 28. The handlebar unit 29 is a portion operated by a rider to steer at least one front wheel 3. In the example shown in FIGS. 2( a) and 2(b), the handlebar unit 29 includes a bar handle formed by an integrated portion gripped by the rider's right hand and a portion gripped by the rider's left hand. However, the handlebar unit 29 may include a separate handlebar in which the portion gripped by the rider's right hand and the portion gripped by the rider's left hand are separate components. The connecting unit 28 connects at least one front wheel 3 to the handlebar unit 29. The connecting unit 28 includes a steering shaft 31 coupled to the handlebar unit 29. The steering shaft 31 is supported by the body frame 5 so as to be rotatable around the steering axis X3 within a rotation angle range of less than 360°. As a result, the handle portion 29 is supported by the body frame 5 so as to be rotatable around the steering axis X3. Here, in the example of FIGS. 2( a) and 2(b), the lean vehicle 1 has one front wheel 3, and the connection portion 28 is configured so that the front wheel 3 can rotate integrally with the connection portion 28 around the steering axis X2 relative to the body frame 5. As a result, the steering axis X3 coincides with the steering axis X2. However, the lean vehicle 1 of the second embodiment may have multiple front wheels 3, and the connection portion 28 may be configured so that each front wheel 3 can rotate integrally with a portion of the connection portion 28 around the steering axis X2 of each front wheel 3, relative to the other portion of the connection portion 28. In this case, the steering axis X3 does not coincide with the steering axis X2 of any of the front wheels 3. Although not shown in FIGS. 2( a) and 2(b), the steering torque imparting device 12 is configured to impart a steering torque to the front wheels 3 about the steering axis X2 by, for example, imparting a torque to the steering shaft 31 about the handle axis X3.In the lean vehicle 1 of the second embodiment, the connection portion 28 is configured so that when the handle portion 29 rotates about the steering axis X3, the at least one front wheel 3 rotates about the steering axis X2, and when the at least one front wheel 3 rotates about the steering axis X2, the handle portion 29 rotates about the steering axis X3. The rotation angle of any one of the at least one front wheels 3 about the steering axis X2 is equal to or greater than the rotation angle of the handle portion 29 about the steering axis X3. As in the example of FIGS. 2( a) and 2(b), when the lean vehicle 1 has one front wheel 3 and the steering axis X3 coincides with the steering axis X2, the rotation angle of the handle portion 29 about the steering axis X3 and the rotation angle of the one front wheel 3 about the steering axis X2 are the same or approximately the same. In the case where the lean vehicle 1 of the second embodiment has two front wheels 3 and the handle axis X3 does not coincide with the steering axis X2 of either of the front wheels 3, the rotation angle of the handle portion 29 about the handle axis X3 may be a rotation angle between the rotation angles of the two front wheels 3 about the steering axis X2.

[0060] Here, in the lean vehicle 1 of the second embodiment, the rotation angle of any one of at least one front wheels 3 about the steering axis X2 is equal to or greater than the rotation angle of the handle unit 29 about the steering axis X3. Therefore, even a small change in the rotation angle of the handle unit 29 about the steering axis X3 results in a large change in friction torque. Also, in the lean vehicle 1 of the second embodiment, the rotation angle range of the handle unit 29 is less than 360°. Therefore, even a small change in the rotation angle of the handle unit 29 about the steering axis X3 results in a large change in friction torque. In the second embodiment, in such a lean vehicle 1 in which a small change in the rotation angle of the handle unit 29 about the steering axis X3 results in a large change in friction torque, the control device 9 controls the steering torque imparting device 12 in the same manner as described in the first embodiment.

[0061] <Modification of Second Embodiment> In the lean vehicle 1 of the second embodiment, the rotation angle of at least one front wheel 3 about the steering axis X2 may be smaller than the rotation angle of the handle section 29 about the steering axis X3, and the rotation angle range of the handle section 29 may be less than 360°. Alternatively, in the lean vehicle 1 of the second embodiment, the rotation angle of any one of the at least one front wheels 3 about the steering axis X2 may be equal to or greater than the rotation angle of the handle section 29 about the steering axis X3, and the rotation angle range of the handle section 29 may be 360° or greater. Alternatively, in the lean vehicle 1 of the second embodiment, the rotation angle of at least one front wheel 3 about the steering axis X2 may be smaller than the rotation angle of the handle section 29 about the steering axis X3, and the rotation angle range of the handle section 29 may be 360° or greater.

[0062] Third Embodiment A lean vehicle 1 according to a third embodiment of the present invention will be described below with reference to FIGS. 3A and 3B. The lean vehicle 1 according to the third embodiment has all of the features of the lean vehicle 1 according to the first embodiment. The lean vehicle 1 according to the third embodiment may also have the features of the lean vehicle 1 according to the second embodiment. In the lean vehicle 1 according to the third embodiment, a contact portion 3a, which is a portion of the outer edge of at least one front wheel 3 in contact with the running surface G in a cross section perpendicular to the circumferential direction, is arc-shaped. When the lean angle φ is 0 and the steering angle δ is 0, the contact position 3b of the contact portion 3a of the front wheel 3 that contacts the running surface G is located on the center line X4 of the front wheel 3 in the width direction, as shown in FIG. 3A, for example. When the lean angle φ changes from 0, the contact position 3b of the contact portion 3a of the front wheel 3 that contacts the running surface G shifts from the center line X4 of the front wheel 3 in the left-right direction of the vehicle, as shown in FIG. 3B, for example. Furthermore, the larger the lean angle φ, the more the contact position 3b deviates from the center line X4 in the vehicle lateral direction. Note that FIG. 3B illustrates a case in which the lean vehicle 1 is tilted to the right with respect to the vehicle vertical direction. Although not illustrated, in a lean vehicle 1 in which the contact portion 3a of the front wheel 3 is arc-shaped, the steering axis X2 is oblique with respect to the vehicle vertical direction, and therefore the contact position 3b of the contact portion 3a of the front wheel 3 contacting the running surface G also varies depending on the steering angle δ of the front wheel 3. Specifically, as the steering angle δ to the right increases, the contact position 3b of the contact portion 3a of the front wheel 3 contacting the running surface G shifts to the right. Furthermore, as the steering angle δ to the left increases, the contact position 3b of the contact portion 3a of the front wheel 3 contacting the running surface G shifts to the left. Thus, in a lean vehicle 1 in which the contact portion 3a of the front wheel 3 is arc-shaped, the contact position 3b of the contact portion 3a varies depending on the lean angle φ and the steering of the front wheel 3. When the contact position 3b of the contact portion 3a is different, the contact area of ​​the contact portion 3a with the running surface G is different, and the friction torque is different.

[0063] In the third embodiment, in a lean vehicle 1 in which the front wheels 3 have arc-shaped contact portions 3a and the friction torque varies depending on the lean angle φ and the steering of the front wheels 3, the control device 9 controls the steering torque imparting device 12 in the same manner as described in the first embodiment.

[0064] Fourth Embodiment A lean-wheel vehicle 1 according to a third embodiment of the present invention will be described below with reference to FIGS. 4A, 4B, and 4C. The lean-wheel vehicle 1 according to the fourth embodiment has all of the features of the lean-wheel vehicle 1 according to the first embodiment. The lean-wheel vehicle 1 according to the fourth embodiment may also have the features of at least one of the lean-wheel vehicle 1 according to the second or third embodiment. Here, friction between the front wheels 3 and the road surface G has hysteresis, and the steering torque required to set the steering angle δ of the front wheels 3 to a certain angle is affected by this hysteresis. Therefore, when the lean-wheel vehicle 1 performs a turning maneuver that alternates between turning right and left in the vehicle's left-right direction, the relationship between the steering angle φ and the steering torque is significantly different between when the front wheels 3 are steered left and when they are steered right, as shown by line L1 in FIG. 4A. Note that line L2 in FIG. 4A shows an example of the relationship between the steering angle φ and the steering torque calculated while ignoring friction between the front wheels 3 and the road surface. Furthermore, the hysteresis varies depending on the friction between the front wheels 3 and the road surface G. The lean vehicle 1 turning may include at least one of the following: the lean vehicle 1 slaloming or the lean vehicle 1 traveling in a figure-eight pattern. When the lean vehicle 1 slaloms, for example, the lean vehicle 1 travels in one direction while alternately turning right and left in the vehicle's left-right direction, thereby traveling along the locus indicated by arrow A1 in FIG. 4B. When the lean vehicle 1 travels in a figure-eight pattern, for example, the lean vehicle 1 travels along the locus indicated by arrow A2 in FIG. 4C, while alternately turning right and left in the vehicle's left-right direction.In the lean vehicle 1 of the fourth embodiment, the control device 9 controls the steering torque imparting device 12 so that, at least when the lean vehicle 1 is turning, a steering torque is imparted to at least one front wheel 3 that is the sum of a steering command torque based at least on the first lean angle information detected by the lean angle-related information detecting device 6, the first steering angle information detected by the steering angle-related information detecting device 7, and the first wheel speed information detected by the wheel speed-related information detecting device 8, and a friction cancellation torque for canceling out the friction torque generated by friction between at least one front wheel 3 and the driving surface G, so as to increase the responsiveness of changes in the lean angle φ to changes in the steering angle δ, as described in the first embodiment.

[0065] Fifth Embodiment A lean-fuel vehicle 1 according to a fifth embodiment of the present invention will be described below with reference to FIG. 5A. The lean-fuel vehicle 1 according to the fifth embodiment has all of the features of the lean-fuel vehicle 1 according to the first embodiment. The lean-fuel vehicle 1 according to the fifth embodiment may also have the features of at least one of the lean-fuel vehicle 1 according to the second to fourth embodiments. In the lean-fuel vehicle 1 according to the fifth embodiment, the control device 9 estimates the friction-cancelling torque T2 based on the value of the steering torque T3 applied to at least one front wheel 3 by the steering torque application device 12 and information detected by the detection devices 6 to 8. Specifically, the control device 9 estimates the friction-cancelling torque T2 in step S2 using an inverse model 41 of the lean vehicle 1. More specifically, the inverse model 41 of the lean vehicle 1 is a model whose input-output relationship is reversed to that of the forward model of the lean vehicle 1 described below. The forward model of the lean vehicle 1 is a model that receives as input an applied torque T5 about the steering axis X2 applied to at least one front wheel 3, and outputs second lean angle information related to the lean angle immediately after the applied torque T5 is applied to at least one front wheel 3, second steering angle information related to the steering angle, and second wheel speed information related to the wheel speed. In other words, the forward model of the lean vehicle 1 models the input and output of the plant 23. The second lean angle information may be the same as the first lean angle information, or may be information different from the first lean angle information obtained from the first lean angle information. For example, the second lean angle information may be the lean angle, and the first lean angle information may be a lean angular velocity. The second steering angle information may be the same as the first steering angle information, or may be information different from the first steering angle information obtained from the first steering angle information. The second wheel speed information may be the same as the first wheel speed information, or may be information different from the first wheel speed information obtained from the first wheel speed information. FIG. 5A shows a case where the second lean angle information, the second steering angle information, and the second wheel speed information are the same as the detection information y described in the first embodiment, but the second lean angle information, the second steering angle information, and the second wheel speed information may be information obtained from the detection information y but different from the detection information y.In the fifth embodiment, the friction offset torque T2 estimated by the control device 9 in step S2 is a torque based on the difference between the steering torque T3 applied to at least one front wheel 3 from the steering torque application device 12 and the inverse model output torque T6 based on the torque output from the inverse model 41 of the lean vehicle 1 when second lean angle information obtained from first lean angle information detected by the lean angle-related information detection device 6 immediately after the steering torque T3 is applied, second steering angle information obtained from the first steering angle information detected by the steering angle-related information detection device 7, and second wheel speed information obtained from the first wheel speed information detected by the wheel speed-related information detection device 8 are input to the inverse model 41 of the lean vehicle 1. In addition, in the lean vehicle 1 of the fifth embodiment, target value information r is stored in the control device 9. The target value information r includes a target value for information related to the lean angle φ, a target value for information related to the steering angle δ, and a target value for information related to the wheel speed S. The target value information r may be data indicating, for example, a combination of the lean angle φ, steering angle δ, and vehicle speed V when the lean vehicle 1 is in an equilibrium state. Furthermore, as shown in FIG. 5A , in the lean vehicle 1 of the fifth embodiment, the steering command torque determiner 21 includes a steering command torque derivation unit 42. The steering command torque derivation unit 42 derives the steering command torque T1 based on a value corresponding to the detection information y and the target value information r. FIG. 5A illustrates a case in which the target value information r and the detection information y contain the same types of information related to the lean angle φ, the steering angle δ, and the wheel speed S, and the steering command torque derivation unit 42 derives the steering command torque T1 based on the difference between the target value information r and the detection information y. The difference between the target value information r and the detection information y refers to the difference between the value of the information related to the lean angle φ, the value of the information related to the steering angle δ, and the value of the information related to the wheel speed S, between the target value information r and the detection information y. The information related to the lean angle φ in the target value information r and the information related to the lean angle φ in the detection information y may be different types of information. Also, the information related to the steering angle δ in the target value information r and the information related to the steering angle δ in the detection information y may be different types of information.Furthermore, the information related to the wheel speed S in the target value information r and the information related to the wheel speed S in the detected information y may be different types of information. In these cases, for example, the target value information r and the detected information y are separately input to the steering command torque derivation unit 42, and the steering command torque derivation unit 42 derives the steering command torque T1 based on this information. Even if the information related to the lean angle φ, the information related to the steering angle δ, and the information related to the wheel speed S in the target value information r and the detected information y are the same types of information, the target value information r and the detected information y may be separately input to the steering command torque derivation unit 42, and the steering command torque derivation unit 42 may derive the steering command torque T1 based on this information. In the fifth embodiment, the applied torque T5 about the steering axis X2 applied to at least one front wheel 3 when the control device 9 controls the steering torque application device 12 by performing processing according to the flowchart of FIG. 1 will be described using the block diagram of FIG. 5( a). As shown in the block diagram of FIG. 5A, in the fifth embodiment, the friction offsetting torque estimator 22 includes the inverse model 41 of the lean vehicle 1 described above. Furthermore, in the fifth embodiment, the friction offsetting torque T2 output by the friction offsetting torque estimator 22 is a torque based on the difference between the steering torque T3 and a torque based on the inverse model output torque T6 output from the inverse model 41 of the lean vehicle 1. While FIG. 5A illustrates a case in which the friction offsetting torque T2 is the difference between the inverse model output torque T6 and the steering torque T3, this is not limiting. For example, the friction offsetting torque T2 may be the difference between the steering torque T3 and a torque calculated by multiplying the inverse model output torque T6 by a coefficient greater than 0 and less than 1. Alternatively, for example, the friction offsetting torque T2 may be a torque calculated by multiplying the difference between the inverse model output torque T6 and the steering torque T3 by a coefficient greater than 0 and less than 1.

[0066] <Modification of Fifth Embodiment> Next, a modification of the fifth embodiment will be described with reference to Fig. 5(b). As shown in Fig. 5(b), in the lean vehicle 1 of the modification of the fifth embodiment, the friction canceling torque estimator 22 includes a low-pass filter 36 in addition to the same configuration as in the fifth embodiment. The low-pass filter 36 removes high-frequency components such as noise contained in the difference between the steering torque T3 and the inverse model output torque T6 output from the inverse model 41 of the lean vehicle 1. As a result, the friction canceling torque T2 output from the friction canceling torque estimator 22 is the difference between the steering torque T3 and the inverse model output torque T6 from which the high-frequency components have been removed.

[0067] Sixth Embodiment A lean-fuel vehicle 1 according to a sixth embodiment of the present invention will now be described with reference to FIG. 6 . The lean-fuel vehicle 1 according to the sixth embodiment has all of the features of the lean-fuel vehicle 1 according to the first embodiment. The lean-fuel vehicle 1 according to the sixth embodiment may also have the features of at least one of the lean-fuel vehicle 1 according to the second to fourth embodiments. In the sixth embodiment, the applied torque T5 about the steering axis X2 applied to at least one front wheel 3 when the control device 9 controls the steering torque application device 12 by performing processing according to the flowchart of FIG. 1 will be described using the block diagram of FIG. 6 . As shown in the block diagram of FIG. 6 , in the sixth embodiment, the friction offsetting torque estimator 22 includes an integrator 51 and a gain application unit 52. The integrator 51 receives the difference between the detection information y and the target value information r and outputs an integral torque T7 corresponding to the integral value obtained by integrating the difference between the input detection information y and the target value information r. The detection information y and the target value information r are, for example, similar to those described in the fifth embodiment. The gain applying unit 52 outputs a value (K×T7) obtained by multiplying the integral torque T7 by a predetermined coefficient K as the friction canceling torque T2.

[0068] 1: lean vehicle, 2: wheel, 3: front wheel, 3a: contact portion, 3b: contact position, 4: rear wheel, 5: vehicle body frame, 6: lean angle related information detection device, 7: steering angle related information detection device, 8: wheel speed related information detection device, 9: control device, 12: steering torque application device, 28: connection portion, 29: handle portion

Claims

1. A plurality of wheels including at least one front wheel and at least one rear wheel disposed rearward of the at least one front wheel in a vehicle longitudinal direction; a vehicle body frame that supports the plurality of wheels rotatably about an axle line, supports the at least one front wheel rotatably about a steering axis line, and tilts to the right of the vehicle relative to the vehicle up-down direction when turning right, and tilts to the left of the vehicle relative to the vehicle up-down direction when turning left; a lean angle related information detection device that detects first lean angle information related to a lean angle, which is an inclination angle of the body frame in a vehicle left-right direction with respect to the vehicle up-down direction; a steering angle related information detection device that detects first steering angle information related to a steering angle, which is a rotation angle of any one of the front wheels about the steering axis; a wheel speed related information detection device that detects first wheel speed information related to a wheel speed, which is a rotational speed of any one of the wheels about the axle line; a steering torque imparting device configured to impart a steering torque about the steering axis to the at least one front wheel; A lean vehicle including: a control device configured to control the steering torque applied by the steering torque application device, the control device controlling the steering torque applied from the steering torque application device to the at least one front wheel such that the steering angle and the lean angle are adjusted; The control device controls the steering torque imparting device so that a steering torque that is the sum of a steering command torque based at least on the first lean angle information detected by the lean angle related information detection device, the first steering angle information detected by the steering angle related information detection device, and the first wheel speed information detected by the wheel speed related information detection device, and a friction cancellation torque for canceling out friction torque generated due to friction between the at least one front wheel and the driving surface, is imparted to the at least one front wheel, so as to increase the responsiveness of changes in the lean angle to changes in the steering angle.

2. A handlebar section operated by a rider; 2. The lean vehicle according to claim 1, further comprising: a connection portion that connects the handle portion and the at least one front wheel, the connection portion being supported by the body frame so that the handle portion is rotatable about a handle axis, the at least one front wheel rotates about the steering axis when the handle portion rotates about the handle axis, the handle portion rotates about the handle axis when the at least one front wheel rotates about the steering axis, and the rotation angle of any of the at least one front wheels about the steering axis is greater than or equal to the rotation angle of the handle portion about the handle axis.

3. A handlebar section operated by a rider; 3. The lean vehicle according to claim 1, further comprising: a connection portion that connects the handle portion and the at least one front wheel, the connection portion being supported by the vehicle body frame so that the handle portion can rotate within a rotation angle range of less than 360° around the handle axis, and the connection portion that connects the handle portion and the at least one front wheel so that when the handle portion rotates around the handle axis, the at least one front wheel rotates around the steering axis, and when the at least one front wheel rotates around the steering axis, the handle portion rotates around the handle axis.

4. 3. The lean vehicle according to claim 1, wherein a contact portion, which is a portion of an outer edge of the at least one front wheel in a cross section perpendicular to a circumferential direction that contacts the running surface, is arc-shaped.

5. The control device controls the steering torque imparting device so that the steering torque imparting device imparts to the at least one front wheel a steering command torque that is based at least on the first lean angle information detected by the lean angle-related information detection device, the first steering angle information detected by the steering angle-related information detection device, and the first wheel speed information detected by the wheel speed-related information detection device, and the friction offsetting torque that is generated due to friction between the at least one front wheel and a driving surface, so as to increase the responsiveness of the change in the lean angle to the change in the steering angle, at least when the lean vehicle is making a turn in which the at least one front wheel is alternately steered to the right of the vehicle and to the left of the vehicle.

6. The lean vehicle described in claim 1 or 2, characterized in that the control device controls the steering torque imparting device so that the steering torque imparted to the at least one front wheel is the sum of the steering command torque based at least on the first lean angle information detected by the lean angle related information detection device, the first steering angle information detected by the steering angle related information detection device, and the first wheel speed information detected by the wheel speed related information detection device, and the friction offsetting torque for offsetting the friction torque generated due to friction between the at least one front wheel and the driving surface, so as to increase the responsiveness of the change in the lean angle to the change in the steering angle, at least when the vehicle speed of the lean vehicle is higher than 0 km / h and not more than 10 km / h.

7. The lean vehicle according to claim 1 or 2, characterized in that when the lean vehicle is traveling autonomously without being driven by a rider or when the lean vehicle is traveling driven by a rider, the control device controls the steering torque imparting device so that the steering torque imparted to the at least one front wheel is the sum of the steering command torque based at least on the first lean angle information detected by the lean angle related information detection device, the first steering angle information detected by the steering angle related information detection device, and the first wheel speed information detected by the wheel speed related information detection device, and the friction offsetting torque for offsetting the friction torque generated by friction between the at least one front wheel and a driving surface, so as to increase the responsiveness of the lean angle change to a change in steering angle at least when the lean vehicle is traveling autonomously without being driven by a rider or when the lean vehicle is traveling driven by a rider.

8. A model having an input of the torque about the steering axis applied to the at least one front wheel and an output of second lean angle information related to the lean angle, second steering angle information related to the steering angle, and second wheel speed information related to the wheel speed immediately after the torque is applied to the at least one front wheel is defined as a forward model of the lean vehicle, and a model having an input / output relationship inverse to that of the forward model of the lean vehicle is defined as an inverse model of the lean vehicle. The lean vehicle according to claim 1 or 2, characterized in that the friction offsetting torque is a torque based on the difference between the steering torque applied to the at least one front wheel from the steering torque application device and a torque based on a torque output from the inverse model of the lean vehicle when the second lean angle information obtained from the first lean angle information detected by the lean angle related information detection device immediately after the steering torque is applied, the second steering angle information obtained from the first steering angle information detected by the steering angle related information detection device, and the second wheel speed information obtained from the first wheel speed information detected by the wheel speed related information detection device are input to the inverse model of the lean vehicle.