Patent Description:
A leaning vehicle having a left wheel, a right wheel and a vehicle body frame capable of tilting relative to the ground has been known in the art. A leaning vehicle has been known in the art, including a tilt sensor that detects the tilt angle of the vehicle body frame, a lean actuator that makes the vehicle body frame tilted or stand upright, and a control device that controls the lean actuator based on the detection result of the tilt sensor, as described in <CIT>, for example.

With the leaning vehicle, the vehicle body frame can self-stand by controlling the lean actuator so that the tilt angle of the vehicle body frame from the vertical line (i.e., the bank angle) is zero, for example. That is, it is possible to perform a self-stand control of making the vehicle body frame self-stand. By performing the self-stand control when the leaning vehicle is stopped, the vehicle body frame can be made to stand upright without the rider supporting the vehicle body frame. With the leaning vehicle described above, the lean actuator tilts the vehicle body frame when turning left or when turning right, allowing the rider to easily turn the leaning vehicle. Thus, with the leaning vehicle described above, various controls are possible by using the tilt sensor and the lean actuator.

Now, when mounting the tilt sensor on the vehicle body frame, the position or attitude of the tilt sensor may shift from the normal position or attitude. That is, an installation error of the tilt sensor may occur. In addition, the mounting part for mounting the tilt sensor on the vehicle body frame may deteriorate over time. When the mounting part deteriorates over time, the position or attitude of the tilt sensor may shift. If the position or attitude of the tilt sensor shifts, the origin position of the tilt sensor shifts from its normal position. Hereinafter, the shift of the origin position from the normal position will be referred to as an origin shift.

If the tilt sensor has an origin shift, it is no longer possible to desirably perform a control using the lean actuator. For example, if the self-stand control is executed without noticing the origin shift of the tilt sensor, the lean actuator will attempt to keep the vehicle body frame in a tilted attitude. Therefore, it is not possible to automatically make the vehicle body frame stand upright.

<CIT> discloses a leaning vehicle with a tilt sensor and a control device that is configured to receive a signal from the tilt sensor.

It is the object of the present invention to provide a leaning vehicle and method for detecting an error in a tilt sensor of a leaning vehicle and a method for calibrating a tilt sensor of a leaning vehicle sensor which can determine the presence/absence of an origin shift of the tilt sensor of a leaning vehicle and/or can calibrate the origin shift of the tilt sensor of a leaning vehicle. According to the present invention said object is solved by a leaning vehicle having the features of independent claim <NUM>. Moreover, according to the present invention said object is solved by a method for detecting an error in a tilt sensor of a leaning vehicle having the features of independent claim <NUM>. Furthermore, said object is solved by a method for calibrating a tilt sensor of a leaning vehicle sensor according to claim <NUM>. Preferred embodiments are laid down in the dependent claims.

A leaning vehicle disclosed herein includes: a vehicle body frame having a head pipe; a left wheel arranged leftward relative to the head pipe; a right wheel arranged rightward relative to the head pipe; a link mechanism that links together the vehicle body frame, the left wheel and the right wheel; a tilt sensor mounted on the vehicle body frame that detects a bank angle of the vehicle body frame; a lean actuator that applies a torque around a rotation axis extending in a vehicle front-rear direction on the vehicle body frame; a control device that receives a signal from the tilt sensor to control the lean actuator; and a torque detection device that detects an output torque of the lean actuator. The control device includes: a self-stand control section that executes a self-stand control of controlling the lean actuator so that a detected bank angle, which is the bank angle of the vehicle body frame detected by the tilt sensor, becomes zero; and a determination section that determines the presence/absence of an origin shift of the tilt sensor based on whether or not the detected bank angle is constant and an absolute value of the output torque of the lean actuator is equal to or greater than a predetermined threshold value while the self-stand control is executed.

With the leaning vehicle described above, when the tilt sensor has no origin shift, the vehicle body frame stands upright by executing the self-stand control. When the vehicle body frame is standing upright, the gravity acting on the vehicle body frame acts vertically downward, and the gravity does not act as a torque that tilts the vehicle body frame. Therefore, even when the absolute value of the output torque of the lean actuator is relatively small, the lean actuator can maintain the vehicle body frame in an upright attitude. Therefore, when the tilt sensor has no origin shift, the absolute value of the output torque of the lean actuator is kept low.

On the other hand, when the tilt sensor has an origin shift, the control device will erroneously recognize an attitude of the vehicle body frame that is tilted from the vertical line as the upright attitude. During the self-stand control, the lean actuator attempts to maintain the vehicle body frame in a tilted attitude. However, when the vehicle body frame is tilted, the gravity acting on the vehicle body frame acts as a torque that tilts the vehicle body frame. Therefore, the lean actuator needs to output a torque commensurate with the torque to maintain the attitude of the vehicle body frame. The lean actuator needs to output a relatively large torque. Therefore, when the tilt sensor has an origin shift, the absolute value of the output torque of the lean actuator is relatively large.

Therefore, by executing the self-stand control while the leaning vehicle is stopped, it is possible to determine the presence/absence of an origin shift of the tilt sensor based on the absolute value of the output torque of the lean actuator. With the leaning vehicle described above, the presence/absence of the origin shift of the tilt sensor is determined based on whether or not the detected bank angle of the tilt sensor is constant and the absolute value of the output torque of the lean actuator is equal to or greater than a threshold value. With the leaning vehicle described above, it is possible to easily determine whether or not the tilt sensor has an origin shift.

The control device may include: a shift amount storage section that stores a predetermined relationship between the output torque of the lean actuator and a shift amount of the tilt sensor; and a shift amount calculation section that calculates the shift amount of the tilt sensor based on the output torque of the lean actuator detected by the torque detection device and the relationship stored in the shift amount storage section if it is determined by the determination section that there is an origin shift.

Therefore, it is possible to quickly calculate the shift amount of tilt sensor based on the output torque of the lean actuator.

The self-stand control section may include: an output torque storage section that stores a predetermined relationship between the detected bank angle and the output torque of the lean actuator; an output torque determination section that determines the output torque of the lean actuator based on the detected bank angle detected by the tilt sensor and the relationship stored in the output torque storage section; and a control execution section that controls the lean actuator so as to output the output torque determined by the output torque determination section. The relationship stored in the shift amount storage section may be such a relationship that a shift amount C of the tilt sensor is C=B-A when the output torque of the lean actuator is T, where T is a torque around the rotation axis of the vehicle body frame that is generated by gravity and acts upon the vehicle body frame when the bank angle of the vehicle body frame is B; and in the relationship stored in the output torque storage section, A is the detected bank angle when the output torque of the lean actuator is T.

The control device may include a calibration section that calibrates an origin position of the tilt sensor from P0 to P0+ΔP, where P0 is the origin position of the tilt sensor and ΔP is the shift amount calculated by the shift amount calculation section.

Therefore, it is possible to automatically calibrate the origin shift of the tilt sensor.

The control device may include an origin position changing section that changes an origin position of the tilt sensor when it is determined by the determination section that there is an origin shift. The self-stand control section may be configured to execute the self-stand control based on the changed origin position after the origin position changing section changes the origin position. The origin position changing section may be configured to repeat changing the origin position of the tilt sensor until it is determined by the determination section that there is no origin shift.

The link mechanism may include: a left wheel support member that supports the left wheel; a right wheel support member arranged rightward of the left wheel support member that supports the right wheel; a link member extending leftward and rightward of the vehicle body frame; a central link shaft extending in a vehicle front-rear direction that rotatably links the vehicle body frame to the link member; a left link shaft extending in the vehicle front-rear direction that rotatably links the left wheel support member to the link member; and a right link shaft extending in the vehicle front-rear direction that rotatably links the right wheel support member to the link member. The lean actuator may be configured to apply a torque around the central link shaft on the vehicle body frame.

The tilt sensor may be an inertial measurement unit IMU provided on the vehicle body frame.

A method for detecting an error in a tilt sensor of a leaning vehicle disclosed herein may be a method for detecting an error in a tilt sensor of a leaning vehicle, the leaning vehicle including a vehicle body frame having a head pipe; a left wheel arranged leftward relative to the head pipe; a right wheel arranged rightward relative to the head pipe; a link mechanism that links together the vehicle body frame, the left wheel and the right wheel; a tilt sensor mounted on the vehicle body frame that detects a bank angle of the vehicle body frame; a lean actuator that applies a torque around a rotation axis extending in a vehicle front-rear direction on the vehicle body frame; and a control device that receives a signal from the tilt sensor to control the lean actuator, the method including: executing a self-stand control of controlling the lean actuator so that a detected bank angle, which is the bank angle of the vehicle body frame detected by the tilt sensor, becomes zero; detecting an output torque of the lean actuator; and determining the presence/absence of an origin shift of the tilt sensor based on whether or not the detected bank angle is constant and an absolute value of the output torque of the lean actuator is equal to or greater than a predetermined threshold value.

A method for calibrating a tilt sensor of a leaning vehicle disclosed herein may be a method for calibrating a tilt sensor of a leaning vehicle, the leaning vehicle including: a vehicle body frame having a head pipe; a left wheel arranged leftward relative to the head pipe; a right wheel arranged rightward relative to the head pipe; a link mechanism that links together the vehicle body frame, the left wheel and the right wheel; a tilt sensor mounted on the vehicle body frame that detects a bank angle of the vehicle body frame; a lean actuator that applies a torque around a rotation axis extending in a vehicle front-rear direction on the vehicle body frame; and a control device that receives a signal from the tilt sensor to control the lean actuator, the method including: executing a self-stand control of controlling the lean actuator so that a detected bank angle, which is the bank angle of the vehicle body frame detected by the tilt sensor, becomes zero; detecting an output torque of the lean actuator; determining the presence/absence of an origin shift of the tilt sensor based on whether or not the detected bank angle is constant and an absolute value of the output torque of the lean actuator is equal to or greater than a predetermined threshold value; when it is determined that there is an origin shift of the tilt sensor, calculating a shift amount ΔP of the tilt sensor based on an output torque of the lean actuator and a predetermined relationship between the output torque of the lean actuator and the shift amount of the tilt sensor; and calibrating an origin position of the tilt sensor from P0 to P0+ΔP, where P0 is the origin position of the tilt sensor.

A method for calibrating a tilt sensor of a leaning vehicle may be a method for calibrating a tilt sensor of a leaning vehicle, the leaning vehicle including: a vehicle body frame having a head pipe; a left wheel arranged leftward relative to the head pipe; a right wheel arranged rightward relative to the head pipe; a link mechanism that links together the vehicle body frame, the left wheel and the right wheel; a tilt sensor mounted on the vehicle body frame that detects a bank angle of the vehicle body frame; a lean actuator that applies a torque around a rotation axis extending in a vehicle front-rear direction on the vehicle body frame; and a control device that receives a signal from the tilt sensor to control the lean actuator, the method including: executing a self-stand control of controlling the lean actuator so that a detected bank angle, which is the bank angle of the vehicle body frame detected by the tilt sensor, becomes zero; detecting an output torque of the lean actuator; determining the presence/absence of an origin shift of the tilt sensor based on whether or not the detected bank angle is constant and an absolute value of the output torque of the lean actuator is equal to or greater than a predetermined threshold value; when it is determined that there is an origin shift of the tilt sensor, changing an origin position of the tilt sensor; executing the self-stand control based on the changed origin position; and repeatedly determining the presence/absence of the origin shift, changing the origin position and executing the self-stand control until it is determined that there is no origin shift.

According to the present invention, it is easy to determine the presence/absence of the origin shift of the tilt sensor in a leaning vehicle. Also, it is easy to calibrate the origin shift of the tilt sensor in a leaning vehicle.

One embodiment of a leaning vehicle will now be described with reference to the drawings. <FIG> is a left side view of a leaning vehicle <NUM> according to the present embodiment. <FIG> is a left side view of a part of the leaning vehicle <NUM>. <FIG> is a left side view of a part of the leaning vehicle <NUM>. <FIG> is a front view of a part of the leaning vehicle <NUM>. <FIG> is a plan view of a part of the leaning vehicle <NUM>. <FIG> is a front view of a part of the leaning vehicle <NUM> when the leaning vehicle <NUM> is tilted leftward.

The terms front, rear, left, right, up and down, as used in the description below, refer to these directions as seen from a virtual rider seated on a seat <NUM> while the leaning vehicle <NUM> is standing upright (standing upright as used herein refers to a state where a vehicle body frame <NUM> to be described below is standing upright) on a horizontal surface with no rider and no load thereon, unless specified otherwise. The designations F, Rr, L, R, U and D, as used in the figures, refer to front, rear, left, right, up and down, respectively.

As shown in <FIG> and <FIG>, the leaning vehicle <NUM> includes the vehicle body frame <NUM>, a link mechanism <NUM>, a left front wheel <NUM>, a right front wheel 3R (see <FIG>), a rear wheel <NUM>, a power unit <NUM>, a seat <NUM> and a storage box <NUM>. The leaning vehicle <NUM> is a three-wheel vehicle with two front wheels <NUM>, 3R and one rear wheel <NUM>.

As shown in <FIG>, the vehicle body frame <NUM> includes a head pipe <NUM>, a down frame <NUM> extending rearward and downward from the head pipe <NUM>, and a seat frame <NUM> extending rearward from the down frame <NUM>. The seat <NUM> is supported by the vehicle body frame <NUM>. Herein, the seat <NUM> is supported by the seat frame <NUM>. The storage box <NUM> is arranged downward of the seat <NUM> and is supported by the seat frame <NUM>. As shown in <FIG>, a steering shaft <NUM> is rotatably supported by the head pipe <NUM>. A steering handle <NUM> is fixed to the steering shaft <NUM>. A throttle grip 15R is provided at the right end portion of the steering handle <NUM>, and a left grip <NUM> is provided at the left end portion of the steering handle <NUM>.

As shown in <FIG>, the present embodiment of the leaning vehicle <NUM> is a scooter. The leaning vehicle <NUM> includes a low footrest <NUM>. The footrest <NUM> is supported by the vehicle body frame <NUM>. Herein, the footrest <NUM> is supported by the down frame <NUM> (see <FIG>). The footrest <NUM> is arranged downward of the seat <NUM>. The footrest <NUM> is a platform for supporting the feet of the rider seated on the seat <NUM>.

As shown in <FIG>, the link mechanism <NUM> is a parallelogram link-type link mechanism. The link mechanism <NUM> is arranged upward relative to the left front wheel <NUM> and the right front wheel 3R. The link mechanism <NUM> includes an upper arm <NUM>, a lower arm <NUM>, a left arm <NUM> and a right arm <NUM>.

The upper arm <NUM> and the lower arm <NUM> extend leftward and rightward. The upper arm <NUM> and the lower arm <NUM> are examples of link members extending leftward and rightward of the vehicle body frame <NUM>. The lower arm <NUM> is arranged downward of the upper arm <NUM>. The upper arm <NUM> and the lower arm <NUM> are arranged forward of the head pipe <NUM> (see <FIG>). The upper arm <NUM> is rotatably linked to the head pipe <NUM> by a first central link shaft 21Cc extending in the vehicle front-rear direction. The lower arm <NUM> is rotatably linked to the head pipe <NUM> by a second central link shaft 22Cc extending in the vehicle front-rear direction.

In the present embodiment, as shown in <FIG>, another lower arm 22B is arranged rearward of the head pipe <NUM>. The lower arm 22B extends leftward and rightward. The lower arm 22B is arranged downward of the upper arm <NUM>. The lower arm 22B is rotatably linked to the head pipe <NUM> by a third central link shaft 23Cc (see <FIG>) extending in the vehicle front-rear direction. Note that another upper arm (not shown) may be arranged rearward of the head pipe <NUM>, and this upper arm may be rotatably linked to the head pipe <NUM> by another central link shaft (not shown) extending in the vehicle front-rear direction. Note however that the other upper arm and the other lower arm 22B arranged rearward of the head pipe <NUM> are optional.

As shown in <FIG>, the left arm <NUM> and the right arm <NUM> extend upward and downward. The left arm <NUM> is arranged leftward of the head pipe <NUM> and the right arm <NUM> is arranged rightward of the head pipe <NUM>. The right arm <NUM> is arranged rightward of the left arm <NUM>. The left arm <NUM> and the right arm <NUM> are arranged rearward of the upper arm <NUM> and the lower arm <NUM>. The left arm <NUM> and the right arm <NUM> are arranged forward of the lower arm 22B. The left arm <NUM> and the right arm <NUM> are rotatably linked to the upper arm <NUM>, the lower arm <NUM> and the lower arm 22B.

Specifically, the upper end portion of the left arm <NUM> is rotatably linked to the left end portion of the upper arm <NUM> by a first left link shaft 21Lc extending in the vehicle front-rear direction. The lower end portion of the left arm <NUM> is rotatably linked to the left end portion of the lower arm <NUM> by a second left link shaft 22Lc extending in the vehicle front-rear direction. The lower end of the left arm <NUM> is rotatably linked to the left end portion of the lower arm 22B by a third left link shaft (not shown) extending in the vehicle front-rear direction. The upper end portion of the right arm <NUM> is rotatably linked to the right end portion of the upper arm <NUM> by the first right link shaft 21Rc extending in the vehicle front-rear direction. The lower end portion of the right arm <NUM> is rotatably linked to the right end portion of the lower arm <NUM> by the second right link shaft 22Rc extending in the vehicle front-rear direction. The lower end portion of the right arm <NUM> is rotatably linked to the right end portion of the lower arm 22B by a third right link shaft (not shown) extending in the vehicle front-rear direction.

The leaning vehicle <NUM> includes a left suspension <NUM> and a right suspension 25R. In the present embodiment, the left suspension <NUM> and the right suspension 25R are telescopic suspensions. The upper end portion of the left suspension <NUM> and the upper end portion of the right suspension 25R are connected to the link mechanism <NUM>. The lower end portion of the left suspension <NUM> is connected to the left front wheel <NUM>, and the lower portion of the right suspension 25R is connected to the right front wheel 3R. Specifically, the upper end portion of the left suspension <NUM> is connected to the lower end portion of the left arm <NUM> via a left bracket <NUM>. The upper end portion of the left suspension <NUM> is connected to the left arm <NUM> so as to be rotatable in the left-right direction of the vehicle body frame <NUM>. The upper end portion of the right suspension 25R is connected to the lower end portion of the right arm <NUM> via a right bracket 26R. The upper end portion of the right suspension 25R is connected to the right arm <NUM> so as to be rotatable in the left-right direction of the vehicle body frame <NUM>.

The left suspension <NUM>, the left bracket <NUM> and the left arm <NUM> together form a left wheel support member <NUM> that supports the left front wheel <NUM>. The right suspension 25R, the right bracket 26R and the right arm <NUM> together form a right wheel support member 19R that supports the right front wheel 3R.

A center plate 27C is fixed to the lower end portion of the steering shaft <NUM>. As shown in <FIG>, the center plate 27C extends forward from the steering shaft <NUM>. A left plate <NUM> is fixed to the left bracket <NUM>. A right plate 27R is fixed to the right bracket 26R. The left plate <NUM>, the center plate 27C and the right plate 27R are linked to a tie rod <NUM> so as to be rotatable left and right. The steering shaft <NUM> is linked to the left arm <NUM> and the right arm <NUM> via the center plate 27C, the tie rods <NUM>, the left plate <NUM> and the right plate 27R.

As shown in <FIG>, the leaning vehicle <NUM> includes a control unit <NUM> that controls the bank angle. Note that in the figures other than <FIG>, the control unit <NUM> is not shown. The bank angle as used herein is the tilt angle θ (see <FIG>) of the vehicle body frame <NUM> from the vertical line. Note that in the present embodiment, the bank angle θ is equal to the angle between the axis of the head pipe <NUM> and the vertical line as viewed in the vehicle front view. The control unit <NUM> controls the bank angle of the vehicle body frame <NUM> by adjusting the rotation of the upper arm <NUM> and the lower arm <NUM> relative to the vehicle body frame <NUM>. The control unit <NUM> is configured to apply a torque to at least one of the upper arm <NUM> and the lower arm <NUM>. The control unit <NUM> is connected to at least one of the upper arm <NUM> and lower arm <NUM>, and to the vehicle body frame <NUM>. In the present embodiment, the control unit <NUM> is connected to the upper arm <NUM> and the head pipe <NUM>. Note however that there is no particular limitation thereto, and the control unit <NUM> may be connected to the lower arm <NUM> and the head pipe <NUM>.

The control unit <NUM> includes a case <NUM>, a lean actuator <NUM>, a gear 35A and a gear 35B arranged inside the case <NUM>, and a control device <NUM> arranged inside the case <NUM>.

The lean actuator <NUM> is a power source that applies a torque around the first central link shaft 21Cc to the vehicle body frame <NUM>. The lean actuator <NUM> may apply a torque directly or indirectly to the vehicle body frame <NUM>. In the present embodiment, the lean actuator <NUM> applies a leftward or rightward torque to the upper arm <NUM>, thereby indirectly applying a rightward or leftward torque to the vehicle body frame <NUM>. In the present embodiment, the lean actuator <NUM> is an electric motor. Note however that the lean actuator <NUM> is not limited to an electric motor as long as the lean actuator <NUM> can generate power.

The lean actuator <NUM> is connected to the gear 35A, and the gear 35A is meshed with the gear 35B. The gear 35A and the gear 35B together form a decelerator. The gear 35B is fixed to an output shaft <NUM>. The output shaft <NUM> is a rotating shaft driven by the lean actuator <NUM> and is connected to the upper arm <NUM>. The torque of the lean actuator <NUM> is transmitted to the upper arm <NUM> via the gear 35A, the gear 35B and the output shaft <NUM>. When the lean actuator <NUM> is driven, a torque around the first central link shaft 21Cc (see <FIG>) is applied to the upper arm <NUM>. Since the upper arm <NUM> is linked to the vehicle body frame <NUM> so as to be rotatable around the first central link shaft 21Cc, when a torque around the first central link shaft 21Cc is applied to the upper arm <NUM>, a torque around the first central link shaft 21Cc is generated in the vehicle body frame <NUM>. Note that while the number of gears interposed between the lean actuator <NUM> and the output shaft <NUM> is two in the present embodiment, there is no limitation on the number of gears.

The leaning vehicle <NUM> includes an IMU (inertial measurement unit) <NUM> mounted on the vehicle body frame <NUM> (see <FIG>). The IMU <NUM> is an example of a tilt sensor that detects the bank angle of the vehicle body frame <NUM>. In the present embodiment, the IMU <NUM> is mounted on the rear portion of the vehicle body frame <NUM>. Note however that there is no particular limitation on the location of installation of the IMU <NUM>. The IMU <NUM> may, for example, be mounted on the front portion of the vehicle body frame <NUM>. The IMU <NUM> may be mounted directly on the vehicle body frame <NUM> or mounted indirectly on the vehicle body frame <NUM> via a part such as a bracket.

The control device <NUM> is communicatively connected to the IMU <NUM> via a wire harness (not shown). The control device <NUM> is configured to receive a signal from the IMU <NUM> and control the lean actuator <NUM>. The control device <NUM> is a computer having a CPU, a ROM and a RAM (not shown).

As shown in <FIG>, a power unit <NUM> is pivotally supported on the vehicle body frame <NUM>. The power unit <NUM> is connected to the rear wheel <NUM> so that power can be transmitted therebetween. The power unit <NUM> generates driving force for traveling. The power unit <NUM> provides power to the rear wheel <NUM>. The power unit <NUM> may include an internal combustion engine or may include an electric motor. In the present embodiment, the power unit <NUM> includes an internal combustion engine.

The leaning vehicle <NUM> includes left and right rear suspensions <NUM>. The left rear suspension <NUM> is arranged leftward of the rear wheel <NUM> and the right rear suspension <NUM> is arranged rightward of the rear wheel <NUM>. Each rear suspension <NUM> includes an upper support portion <NUM> pivotably supported on the vehicle body frame <NUM> and a lower support portion <NUM> pivotably supported on the rear wheel <NUM>. Herein, the upper support portion <NUM> is pivotably supported on the seat frame <NUM> via a bracket 13B. The lower support portion <NUM> is pivotably supported on a bracket 4B mounted on the axle of the rear wheel <NUM>.

With the leaning vehicle <NUM>, it is possible to perform various controls using the control device <NUM> to control the lean actuator <NUM>. For example, the control device <NUM> can execute a self-stand control of automatically keeping the vehicle body frame <NUM> in an upright attitude while the leaning vehicle <NUM> is stopped. The control performed by the control device <NUM> is executed based on the bank angle detected by the IMU <NUM>.

Now, when the IMU <NUM> is directly or indirectly mounted on the vehicle body frame <NUM>, the position of the IMU <NUM> may shift from the normal position or the attitude of the IMU <NUM> may tilt from the normal attitude. The mounting part (e.g., a bracket) for mounting the IMU <NUM> on the vehicle body frame <NUM> may deteriorate over time. The position or attitude of the IMU <NUM> may shift from the normal position or attitude due to aging deterioration of the mounting part. If the position or attitude of the IMU <NUM> shifts, the origin position of the IMU <NUM> will shift from the normal position. That is, the IMU <NUM> has an origin shift.

When the IMU <NUM> has an origin shift, it is not possible to desirably execute a control that is executed based on the detection result of the IMU <NUM>. Therefore, it is important to know whether or not the IMU <NUM> has an origin shift. Now, in order to determine the presence/absence of an origin shift of the IMU <NUM>, one may consider periodically taking the leaning vehicle <NUM> to an inspection site, and inspecting the origin shift using an inspection apparatus provided at the inspection site. However, such an inspection takes labor and time.

According to the present embodiment, it is possible to shorten such labor and time. As will be described below, the leaning vehicle <NUM> according to the present embodiment has a function to determine the presence/absence of an origin shift of the bank angle of the IMU <NUM>. The leaning vehicle <NUM> also includes a function to automatically calibrate the origin shift of the bank angle of the IMU <NUM>. According to the present embodiment, it is easy to determine the presence/absence of, and calibrate, the origin shift of the bank angle of the IMU <NUM>. Next, the method of determining and calibrating the origin shift of the bank angle of IMU <NUM> (hereinafter referred to simply as "origin shift") will be described.

When the IMU <NUM> has no origin shift, the bank angle detected by the IMU <NUM> coincides with the actual bank angle of the vehicle body frame <NUM>. Hereafter, the bank angle detected by the IMU <NUM> will be referred to as the "detected bank angle" and the actual bank angle of the vehicle body frame <NUM> will be referred to as the "actual bank angle". As schematically shown in <FIG>, when there is no origin shift, the vehicle body frame <NUM> stands upright when the self-stand control is executed. Since the gravity G acting on the vehicle body frame <NUM> acts vertically downward, when the vehicle body frame <NUM> is standing upright, the gravity G does not act as a torque to tilt the vehicle body frame <NUM>. Therefore, even if the output torque of the lean actuator <NUM> is relatively small, the lean actuator <NUM> can maintain the vehicle body frame <NUM> in an upright attitude. Therefore, when there is no origin shift, the output torque of the lean actuator <NUM> is kept low.

On the other hand, if there is an origin shift, the detected bank angle does not coincide with the actual bank angle. In the case where there is an origin shift, the detected bank angle becomes zero when the vehicle body frame <NUM> is tilted from the vertical line VL, as shown with exaggeration in <FIG>. The control device <NUM> controls the lean actuator <NUM> so that the detected bank angle becomes zero during a self-stand control. Therefore, the control device <NUM> attempts to maintain the vehicle body frame <NUM> in a tilted attitude. However, when the vehicle body frame <NUM> is tilted, the gravity G acting on the vehicle body frame <NUM> acts as a torque that causes the vehicle body frame <NUM> to tilt. Specifically, the vector component Gr of the gravity G in the direction perpendicular to the vehicle up-down direction of the vehicle body frame <NUM> acts as a torque that causes the vehicle body frame <NUM> to tilt. Therefore, the lean actuator <NUM> needs to output a torque commensurate with the torque to maintain the attitude of the vehicle body frame <NUM> (in other words, to prevent the vehicle body frame <NUM> from collapsing). The lean actuator <NUM> needs to output a relatively large torque. Therefore, in the case where there is an origin shift, the output torque of the lean actuator <NUM> is relatively large.

Therefore, by executing the self-stand control while the leaning vehicle <NUM> is stopped, it is possible to determine the presence/absence of an origin shift of the IMU <NUM> based on the magnitude of the output torque of the lean actuator <NUM>. The present embodiment of the control device <NUM> includes the following elements for determining the presence/absence of, and calibrate, the origin shift.

As shown in <FIG>, the leaning vehicle <NUM> includes a torque detection device <NUM> that detects the output torque of the lean actuator <NUM>. Note that it is assumed in the present embodiment that the output torque of the lean actuator <NUM> is positive when the vehicle body frame <NUM> is driven rightward and is negative when it is driven leftward. Note however that the positive and negative directions may be reversed. The control device <NUM> includes a self-stand control section <NUM> that executes a self-stand control, a determination section <NUM> that determines the presence/absence of an origin shift, a shift amount storage section <NUM>, a shift amount calculation section <NUM>, and a calibration section <NUM> that calibrates the origin shift.

The determination section <NUM> determines presence/absence of an origin shift of the bank angle of the IMU <NUM> based on whether or not the detected bank angle is constant and the absolute value of the output torque of the lean actuator <NUM> is equal to or greater than a predetermined threshold value while the self-stand control is being executed. If the absolute value of the output torque is equal to or greater than the threshold value, the determination section <NUM> determines that there is an origin shift, and if the absolute value of the output torque is less than the threshold value, it is determined that there is no origin shift.

The self-stand control section <NUM> controls the lean actuator <NUM> so that the detected bank angle of the IMU <NUM> becomes zero. When the vehicle body frame <NUM> tilts, the lean actuator <NUM> outputs a torque to raise the vehicle body frame <NUM>. Herein, the lean actuator <NUM> needs to output a larger torque the larger the bank angle of the vehicle body frame <NUM>. The magnitude of the torque that needs to be output by the lean actuator <NUM> can be determined in advance by testing or calculation based on the bank angle. As shown in <FIG>, the self-stand control section <NUM> includes an output torque storage section <NUM> that stores a predetermined relationship between the detected bank angle and the output torque of the lean actuator <NUM> (hereinafter referred to as the first relationship). The output torque storage section <NUM> is, for example, a memory. The self-stand control section <NUM> includes the output torque determination section <NUM> and a control execution section <NUM>. The output torque determination section <NUM> receives a signal from the IMU <NUM> and determines the output torque of the lean actuator <NUM> based on the detected bank angle detected by the IMU <NUM> and the first relationship stored in the output torque storage section <NUM>. The control execution section <NUM> controls the lean actuator <NUM> to output the output torque determined by the output torque determination section <NUM>.

The shift amount storage section <NUM> stores a predetermined relationship between the output torque of the lean actuator <NUM> and the shift amount of the bank angle of the IMU <NUM> (hereinafter referred to as the second relationship). The second relationship can be determined, for example, as follows.

As described above, when the vehicle body frame <NUM> is tilted, the gravity acting on the vehicle body frame <NUM> acts as a torque that causes the vehicle body frame <NUM> to tilt (see <FIG>). When the vehicle body frame <NUM> is tilted, a torque around the rotation axis extending in the vehicle front-rear direction is generated on the vehicle body frame <NUM>. While this torque varies in accordance with the actual bank angle of the vehicle body frame <NUM>, it can be determined in advance by testing or calculation. The relationship between the actual bank angle and the torque acting on the vehicle body frame <NUM> will be referred to as the third relationship. As shown in <FIG>, T denotes the torque acting on the vehicle body frame <NUM> due to gravity when the actual bank angle of the vehicle body frame <NUM> is B.

When the output torque TA of the lean actuator <NUM> becomes equal to the torque T during the self-stand control, the vehicle body frame <NUM> stops in the tilted attitude. Then, the detected bank angle detected by the IMU <NUM> is constant. While the self-stand control is performed, the lean actuator <NUM> outputs a torque in accordance with the detected bank angle. The output torque of the lean actuator <NUM> is determined based on the detected bank angle and the first relationship stored in the output torque storage section <NUM>. Herein, based on the first relationship, it is assumed that TA denotes the output torque of the lean actuator <NUM> when the detected bank angle is A.

Where C denotes the shift amount of the origin of the bank angle of the IMU <NUM>, the actual bank angle B is B=A+C when the detected bank angle is A. Therefore, the shift amount C=B-A. The torque T generated by gravity is equal to the output torque TA of the lean actuator <NUM>. The output torque TA of the lean actuator <NUM> is detected by the torque detection device <NUM>. Therefore, the torque T due to gravity can be detected by the torque detection device <NUM>. Once the torque T is known, the actual bank angle B can be identified by the torque T and the third relationship. The detected bank angle A can also be identified by the output torque TA of the lean actuator <NUM> detected by the torque detection device <NUM> and the first relationship. Therefore, the shift amount C can be identified based on the output torque TA of the lean actuator <NUM>.

Thus, the relationship (the second relationship) between the output torque TA of the lean actuator <NUM> and the shift amount C can be identified in advance. For example, as shown in <FIG>, the relationship between the output torque TA and the shift amount C can be stored in advance as a map in the shift amount storage section <NUM>.

The shift amount calculation section <NUM> calculates the shift amount of the IMU <NUM> based on the output torque of the lean actuator <NUM> detected by the torque detection device <NUM> and the second relationship stored in the shift amount storage section <NUM> when the determination section <NUM> determines that there is an origin shift.

The calibration section <NUM> calibrates the origin position of the bank angle of the IMU <NUM> from P0 to P0+ΔP, where P0 is the origin position of the bank angle of the IMU <NUM> and ΔP is the shift amount calculated by the shift amount calculation section <NUM>.

The leaning vehicle <NUM> is configured as described above. Note that the output torque determination section <NUM> and the control execution section <NUM> of the self-stand control section <NUM>, the determination section <NUM>, the shift amount calculation section <NUM> and the calibration section <NUM> are generated, for example, by the CPU of a computer executing a computer program. The output torque storage section <NUM> of the self-stand control section <NUM> and the shift amount storage section <NUM> are a memory of a computer, for example. Next, referring to the flow chart of <FIG>, the method of determining the presence/absence of, and calibrating, the origin shift of the IMU <NUM> will be described.

The determination of the presence/absence of, and the calibration of, the origin shift are performed while the leaning vehicle <NUM> is stopped on a horizontal plane. First, in step S1, the self-stand control section <NUM> starts the self-stand control. Next, in step S2, the determination section <NUM> determines whether or not the detected bank angle detected by the IMU <NUM> is constant. The process proceeds to step S3 if the determination result is YES. In step S3, the torque detection device <NUM> detects the output torque of the lean actuator <NUM>. Note that while step S3 is herein performed after step S2, there is no particular limitation on the order of step S2 and step S3. In step S4, the determination section <NUM> determines whether or not the absolute value of the output torque is equal to or greater than a threshold value. If the determination result from step S4 is YES, the process proceeds to step S5, and it is determined that there is an origin shift. If the determination result from step S4 is NO, the process proceeds to step S8, and it is determined that there is no origin shift.

If it is determined that there is an origin shift, the process proceeds to step S6. In step S6, the shift amount calculation section <NUM> calculates the shift amount of the bank angle of the IMU <NUM> based on the output torque and the second relationship stored in the shift amount storage section <NUM>. Next, the process proceeds to step S7, and the calibration section <NUM> calibrates the origin position from P0 to P0+ΔP, where P0 is the origin position of the bank angle of the IMU <NUM> and ΔP is the shift amount.

Thus, the bank angle of the IMU <NUM> is automatically calibrated. Then, the leaning vehicle <NUM> can execute various controls using the calibrated IMU <NUM>.

As described above, according to the present embodiment, by executing the self-stand control while the leaning vehicle <NUM> is stopped, it is possible to determine the presence/absence of the origin shift of the bank angle of the IMU <NUM> based on the magnitude of the output torque of the lean actuator <NUM>. There is no need to bring the leaning vehicle <NUM> to an inspection site where an inspection apparatus is installed in order to determine the presence/absence of the origin shift of the IMU <NUM>. No special inspection apparatus is needed to determine the presence/absence of the origin shift of the IMU <NUM>. According to the present embodiment, it is possible to easily determine the origin shift of the IMU <NUM>.

According to the present embodiment, the control device <NUM> includes the shift amount storage section <NUM> and the shift amount calculation section <NUM>. The shift amount storage section <NUM> stores a predetermined relationship (second relationship) between the output torque of the lean actuator <NUM> and the shift amount of the IMU <NUM>. When it is determined by the determination section <NUM> that there is an origin shift, the shift amount calculation section <NUM> calculates the shift amount of the IMU <NUM> based on the output torque of the lean actuator <NUM> and the second relationship. According to the present embodiment, it is possible to quickly calculate the shift amount of the IMU <NUM>.

According to the present embodiment, the calibration section <NUM> calibrates the origin position of the IMU <NUM> after the shift amount calculation section <NUM> calculates the shift amount. Therefore, it is possible to automatically calibrate the origin shift of the bank angle of the IMU <NUM>.

In the embodiment described above, the shift amount calculation section <NUM> calculates the shift amount, and the calibration section <NUM> calibrates the origin position of the IMU <NUM> based on the shift amount. However, the shift amount calculation section <NUM> may be optional. The second embodiment to be described below is similar to the first embodiment but with a change to the method of calibrating the origin position.

As shown in <FIG>, the control device <NUM> according to the second embodiment includes the origin position changing section <NUM> instead of the shift amount storage section <NUM>, the shift amount calculation section <NUM> and the calibration section <NUM>. If it is determined by the determination section <NUM> that there is an origin shift, the origin position changing section <NUM> changes the origin position of the IMU <NUM>. The origin position changing section <NUM> repeatedly changes the origin position until it is determined by the determination section <NUM> that there is no origin shift. Note that the origin position changing section <NUM> is generated, for example, by the CPU of a computer executing a computer program.

<FIG> is a flow chart showing a method of calibrating the origin shift according to the second embodiment. Steps S1 to S5 and S8 are similar to those in the first embodiment. In the present embodiment, after it is determined in step S5 that there is an origin shift, the process proceeds to step S20, and the origin position is changed by the origin position changing section <NUM>. After the origin position is changed, the process returns to step S2, repeating the processes of step S2 and thereafter. In step S4, it is again determined whether or not the absolute value of the output torque of the lean actuator <NUM> is equal to or greater than a threshold value based on the changed origin position. If the output torque is equal to or greater than the threshold value, it is determined in step S5 that there is an origin shift and the process again proceeds to step S20. Thereafter, this process is repeated until it is determined that there is no origin shift (step S8).

Changing the origin position in step S20 can be done as follows, for example. As shown in <FIG>, in the present embodiment, after step S5, it is determined in step S21 whether or not the output torque of the lean actuator <NUM> is greater than <NUM>. Note that it is assumed also in the present embodiment that the output torque of the lean actuator <NUM> is positive when the vehicle body frame <NUM> is driven rightward and is negative when it is driven leftward. When the vehicle body frame <NUM> is tilted leftward relative to the vertical line, the lean actuator <NUM> drives the vehicle body frame <NUM> rightward, so the output torque is greater than <NUM>. When the vehicle body frame <NUM> is tilted rightward relative to the vertical line, the lean actuator <NUM> drives the vehicle body frame <NUM> leftward, so the output torque is less than <NUM>.

If the output torque is greater than <NUM> as a result of determination of step S21, the process proceeds to step S22. In step S22, the origin position P0 is changed to P0-Δ/2n-<NUM>. Note that Δ is a predetermined constant, and n represents the number of repetitions of step S20. Since n=<NUM> when executing step S20 for the first time, the origin position P0 is changed to P0-Δ. If the output torque is smaller than <NUM> as a result of determination of step S21, the process proceeds to step S23. In step S23, the origin position P0 is changed to P0+Δ/2n-<NUM>.

After step S22 or S23, the process proceeds to step S24, adding <NUM> to the number of repetitions. That is, n is changed to n+<NUM>. Then, the process returns to step S4.

This is an example of a specific process of step S20. Note however that the process is merely an example, and there is no particular limitation on the specific process of step S20.

Also in the present embodiment, it is possible to automatically calibrate the origin shift of the bank angle of the IMU <NUM>. According to the present embodiment, the shift amount storage section <NUM> and the shift amount calculation section <NUM> are not necessary.

While the first and second embodiments have been described above, the embodiments are merely illustrative. Various other embodiments are possible.

The tilt sensor for detecting the bank angle of the vehicle body frame <NUM> is not limited to the IMU <NUM>.

The control device <NUM> does not need to be arranged inside the control unit <NUM>. The position of the control device <NUM> is not limited to the front portion of the leaning vehicle <NUM>. While the control device <NUM> may be separate from the control device for controlling the power unit <NUM>, the control device <NUM> may be integral with the control device.

With the error detection method according to the embodiments described above, the determination of the presence/absence of the origin shift of the IMU <NUM> is performed by the control device <NUM>, but the determination of the presence/absence of the origin shift may be performed by a person. For example, a maintenance personnel of the leaning vehicle <NUM> may determine the presence/absence of the origin shift of the IMU <NUM> based on whether or not the detected bank angle is constant and the absolute value of the output torque of the lean actuator <NUM> is equal to or greater than a threshold value. When a maintenance personnel, etc., performs the determination, the second relationship described above does not need to be stored in the computer and may be described, for example, in the operation manual. The maintenance personnel, etc., may perform the determination while referring to the operation manual. Although the calibration method of the embodiments described above is performed by the control device <NUM>, it may be performed by a person such as a maintenance personnel. For example, in the first embodiment, a maintenance personnel, etc., may perform the calibration while referring to the operation manual in which the third relationship is described. In the second embodiment, a maintenance personnel, etc., may change the origin position while visually observing the condition of the leaning vehicle <NUM>.

The leaning vehicle is not limited to a three-wheeled vehicle having the left front wheel <NUM>, the right front wheel 3R and the rear wheel <NUM>. The leaning vehicle may be a three-wheeled vehicle including a front wheel, a left rear wheel and a right rear wheel. The leaning vehicle is not limited to a scooter. The leaning vehicle may be a straddled vehicle other than a scooter. Note that a straddled vehicle is a vehicle to be straddled by a rider.

Claim 1:
A leaning vehicle (<NUM>), comprising:
a vehicle body frame (<NUM>) having a head pipe (<NUM>);
a left wheel (<NUM>) arranged leftward relative to the head pipe (<NUM>);
a right wheel (3R) arranged rightward relative to the head pipe (<NUM>);
a link mechanism (<NUM>) that links together the vehicle body frame (<NUM>), the left wheel (<NUM>) and the right wheel (3R);
a tilt sensor (<NUM>) mounted on the vehicle body frame (<NUM>) that is configured to detect a bank angle (θ) of the vehicle body frame (<NUM>);
a lean actuator (<NUM>) that is configured to apply a torque around a rotation axis extending in a vehicle front-rear direction on the vehicle body frame (<NUM>);
a control device (<NUM>) that is configured to receive a signal from the tilt sensor (<NUM>) to control the lean actuator (<NUM>); and
a torque detection device (<NUM>) that is configure to detect an output torque of the lean actuator (<NUM>),
wherein the control device (<NUM>) includes:
a self-stand control section (<NUM>) that is configured to execute a self-stand control of controlling the lean actuator (<NUM>) so that a detected bank angle (θ), which is the bank angle (θ) of the vehicle body frame (<NUM>) detected by the tilt sensor (<NUM>), becomes zero; and
a determination section (<NUM>) that is configured to determine the presence/absence of an origin shift of the tilt sensor (<NUM>) based on whether or not the detected bank angle (θ) is constant and an absolute value of the output torque of the lean actuator (<NUM>) is equal to or greater than a predetermined threshold value while the self-stand control is executed.