Steering control system for motorcycles

Abstract

To provide a steering control system of a two-wheeled vehicle which can improve the operability of steering.SOLUTION: A control device (100) calculates a resistance torque which is a torque in a direction opposite to a rotation direction of a steering shaft (3) rotating from a neutral position and corresponds to a vehicle turning value that is a rotation angle of the steering shaft (3) or a roll angle of a vehicle body, and controls an actuator so as to add the torque to the steering shaft (3).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a steering control system for a two-wheeled vehicle. [Background technology]

[0002] Bicycles are commonly used that have a front basket attached to the steering wheel (handle) for carrying luggage or children. The weight of the load on the front basket can sometimes exert a force that rotates the steering wheel. Patent Documents 1 and 2 listed below disclose technologies for suppressing steering wheel rotation.

[0003] In Patent Document 1, an electric motor is provided on a steering shaft. The electric motor is controlled so that the angular velocity of the steering shaft does not exceed an angular velocity range set according to the vehicle speed and load weight, or so that the angular position of the steering shaft does not exceed an angle range set according to the vehicle speed and load weight. In Patent Document 2, an electronically controlled steering damper that applies a damping force to the rotation of the steering shaft is provided on the steering shaft. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-005935 [Patent Document 2] International Publication No. 2017 / 057514 Summary of the Invention [Problem to be solved by the invention]

[0005] The controls proposed in Patent Documents 1 and 2 cannot be said to be sufficient in terms of steering operability.

[0006] For example, in Patent Document 1, the actuator is controlled so that the angular velocity of the steering shaft falls within a range set according to the vehicle speed, etc. Therefore, if the driver intends to operate the steering wheel quickly, the steering operability may be impaired. Also, in Patent Document 1, the actuator is controlled so that the angular position of the steering shaft falls within a range set according to the vehicle speed, etc. Therefore, if the driver intends to turn the steering wheel widely, the steering operability may be impaired.

[0007] In Patent Document 2, an oil-powered damper is used instead of an electric motor, so resistance acts on the steering movement even when there is no need to restrict the steering movement. For example, if the driver tries to quickly turn the steering wheel to the left while the vehicle is turning right, a force that restricts the leftward turn acts, which actually impedes steering operability.

[0008] The present disclosure provides a steering control system for a motorcycle that can improve steering operability. [Means for solving the problem]

[0009] (1) The steering control system proposed in the present disclosure includes an actuator that applies torque to a steering shaft that includes an electric motor and that can rotate right and left from a neutral position, a sensor that detects a vehicle turning value that is the rotation angle of the steering shaft or the roll angle of the vehicle body, and a control device that calculates a resistance torque that is a torque in the opposite direction to the direction in which the steering shaft rotates from the neutral position and that corresponds to the vehicle turning value, and controls the actuator based on the resistance torque. This can further improve steering operability.

[0010] (2) In the steering control system of (1), the control device may calculate an assist torque, which is a torque in the same direction as a torque acting on the steering shaft due to a driver's operation, based on the torque acting on the steering shaft or the roll angular velocity of the vehicle. The control device may calculate an output torque to be applied to the steering shaft based on the resistance torque and the assist torque. This makes it possible to apply an appropriate torque to the steering shaft depending on the state of the two-wheeled vehicle.

[0011] (3) In the steering control system (2), the control device may calculate the output torque by adding or subtracting the resistance torque and the assist torque.

[0012] (4) In the steering control system of (2) or (3), the control device may calculate the output torque in the opposite direction to the direction in which the steering shaft is rotating from the neutral position when the resistance torque is greater than the assist torque. When the resistance torque is smaller than the assist torque, the control device may calculate the output torque in the same direction as the torque acting on the steering shaft due to the driver's operation.

[0013] (5) In the steering control system according to any one of (1) to (4), the absolute value of the resistance torque may increase as the vehicle turning value increases. This allows a torque corresponding to the rotation angle of the steering shaft or the roll angle of the vehicle body to be applied to the steering shaft.

[0014] (6) In any one of the steering control systems (1) to (5), when the absolute value of the vehicle turning value is lower than a threshold value, the resistance torque may be substantially 0. This makes it possible to suppress the application of resistance torque to the steering shaft due to minute changes in the vehicle turning value.

[0015] (7) In the steering control system of any one of (2) to (4), the output torque may be smaller than the torque acting on the steering shaft due to the load weight of the vehicle, thereby preventing the steering from automatically returning to the neutral position against the driver's intention.

[0016] (8) In any one of the steering control systems (2) to (4) and (7), the output torque may be less than 10 Newton meters (Nm), which allows the driver to rotate the steering wheel against the torque applied to the steering shaft by the actuator.

[0017] (9) In any one of the steering control systems (1) to (8), the actuator may include a transmission mechanism that transmits torque to the steering shaft. The transmission mechanism may include a member that limits transmission of torque greater than a threshold. This allows the driver of the two-wheeled vehicle to operate the steering wheel against the torque transmitted to the steering shaft.

[0018] (10) In any one of the steering control systems (1) to (9), the output shaft of the electric motor may be disposed away from the steering shaft. The transmission mechanism may include a belt that transmits the torque of the output shaft of the electric motor to the steering shaft as a member that limits the transmission of torque greater than a threshold value. This makes it possible to limit the transmission of torque greater than a threshold value to the steering shaft.

[0019] (11) In any one of the steering control systems (1) to (10), the control device may calculate the resistance torque based on the vehicle turning value and a vehicle speed.

[0020] (12) In the steering control system (11), the control device may calculate the resistance torque so that the resistance torque when the vehicle speed is in a first vehicle speed range is smaller than the resistance torque when the vehicle speed is in a second vehicle speed range that is slower than the first vehicle speed range.

[0021] (13) In any one of the steering control systems (1) to (12), the control device may calculate the resistance torque based on the weight of the vehicle and / or the weight of luggage loaded on the vehicle. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a side view showing an example of a two-wheeled vehicle equipped with a steering control system proposed in the present disclosure. [Figure 2] FIG. 2 is an enlarged view of the steering control system of FIG. 1. [Figure 3] FIG. 2 is a block diagram showing hardware of a steering control system. [Figure 4] FIG. 10 is a diagram showing an example of changes in roll angle and roll angular velocity when a two-wheeled vehicle is being steered. [Figure 5A] 10 is a graph showing the correlation between roll angular velocity and load torque. [Figure 5B] 10 is a graph showing the correlation between roll angle and load torque. [Figure 6] FIG. 2 is a functional block diagram showing functions of a control device provided in the two-wheeled vehicle. [Figure 7] FIG. 4 is a diagram illustrating an example of a map stored in a storage unit. [Figure 8] FIG. 4 is a diagram illustrating an example of a map stored in a storage unit. [Figure 9] FIG. 4 is a diagram illustrating an example of a map stored in a storage unit. [Figure 10] FIG. 4 is a diagram illustrating an example of a map stored in a storage unit. [Figure 11] FIG. 3 is a flowchart showing an example of a control process executed by the steering control system. DETAILED DESCRIPTION OF THE INVENTION

[0023] An example of an embodiment of a steering control system for a two-wheeled vehicle proposed in this disclosure will be described below. FIG. 1 is a side view showing the front of a two-wheeled vehicle 1 equipped with a steering control system 10 according to an embodiment. FIG. 2 is an enlarged view of the steering control system 10 shown in FIG. 1. The two-wheeled vehicle 1 may be, for example, an electrically assisted bicycle having an assist system that transmits power from an electric motor to a wheel (e.g., the rear wheel) to assist the rider in pedaling, or it may be a bicycle without such an assist system. The two-wheeled vehicle 1 may also be a motorcycle that is self-propelled by power from a motor such as a gasoline motor or an electric motor.

[0024] [1. Overview of motorcycles] As shown in Figure 1, two-wheeled vehicle 1 has, at its front, a steering wheel (handle) 2 grasped by the rider, a rod-shaped steering shaft 3 to which steering wheel 2 is fixed, and a frame 4. Frame 4 has, at its front end, a head pipe 4a that holds steering shaft 3 so that it can rotate. Two-wheeled vehicle 1 also has a front wheel 7a, a rear wheel 7b, and a saddle (seat) 8 on which the rider sits. If two-wheeled vehicle 1 is a bicycle, two-wheeled vehicle 1 may have pedals 9a and a crankshaft 9b to which pedals 9a are attached.

[0025] The steering shaft 3 may extend in a direction perpendicular to the direction in which the front wheel 7a and the rear wheel 7b are aligned in the two-wheeled vehicle 1, or may be inclined toward the front wheel 7a or the rear wheel 7b with respect to the perpendicular direction. The steering shaft 3 is rotatable right and left from a neutral position in response to operation of the steering wheel 2 by the rider. The head pipe 4a houses the lower end of the steering shaft 3. The head pipe 4a has a fastener 4b at its upper end. The steering shaft 3 may be supported by the head pipe 4a, with its position in the up-down direction relative to the head pipe 4a fixed by the fastener 4b.

[0026] In the example shown in Fig. 1, the two-wheeled vehicle 1 has a front basket 6 attached to the steering shaft 3. The front basket 6 can move left and right in accordance with the rotation of the steering shaft 3. In addition to the front basket 6, or instead of the front basket 6, the two-wheeled vehicle 1 may have a child seat (not shown) attached to the steering shaft 2 and / or the steering shaft 3.

[0027] For example, when the weight of the front basket 6 or a child seat is heavy or when the two-wheeled vehicle 1 is traveling at high speed, a large force is required to rotate the steering wheel 2 when the vehicle starts to turn and to return the steering wheel 2 to the neutral position when the turn is completed. Also, for example, when the vehicle is turning right and the driver quickly turns the steering wheel 2 to the left, it is preferable to be able to perform a quick turn in accordance with the driver's intention. The two-wheeled vehicle 1 may have a steering control system 10, which will be described below, to assist the driver in operating the steering wheel 2.

[0028] [2. Steering control system overview] 2, the steering control system 10 has an electric motor 11 as a component of an actuator that applies torque to the steering shaft 3. The steering control system 10 may also have a transmission mechanism 20 that transmits torque from the electric motor 11 to the steering shaft 3 as a component of the actuator.

[0029] 2, the transmission mechanism 20 may have a first gear 21 fixed to the output shaft 11a of the electric motor 11 and a second gear 22 fixed to the steering shaft 3. The output shaft 11a of the electric motor 11 may extend in the same direction (up-down direction) as the steering shaft 3. Furthermore, the gears 21 and 22 may be aligned in the front-rear direction.

[0030] The transmission mechanism 20 may include a member that limits the transmission of torque greater than a threshold value. In the example shown in FIG. 2 , the transmission mechanism 20 includes a belt 23 that transmits the torque of the output shaft 11a of the electric motor 11 to the steering shaft 3 as a member that limits the transmission of torque greater than a threshold value. The belt 23 may be made of, for example, rubber or resin. Convex and concave portions formed on the inner surface of the belt 23 mesh with concave and convex portions of the pulleys 21 and 22. The transmission mechanism 20 transmits the rotational force of the electric motor 11 to the steering shaft 3 via the pulleys 21 and 22 and the belt 23, thereby applying torque to the steering shaft 3 in the circumferential direction of the steering shaft 3. Furthermore, when torque greater than a threshold value is applied to the transmission mechanism 20, the convex and concave portions of the belt 23 disengage from the concave and convex portions of the pulley 21 or 22 (i.e., the belt 23 slips relative to the pulley 21 or 22). This limits the transmission of torque greater than the threshold value to the steering shaft 3. A driver of the two-wheeled vehicle 1 can operate the steering wheel 2 against the torque transmitted to the steering shaft 3 .

[0031] The steering control system 10 may have a steering sensor 30 that detects the rotation angle (steering angle) of the steering wheel 2. The electric motor 11 and the steering sensor 30 may be positioned relative to the steering axis 3 in a direction intersecting the steering axis 3. In the example shown in FIG. 2 , the electric motor 11 and the steering sensor 30 are fixed to a support base 12 attached to the frame 4, and are arranged behind the steering axis 3. The electric motor 11 and the steering sensor 30 are lined up in the front-to-rear direction on the support base 12.

[0032] As shown in FIG. 2, a first gear 31 may be fixed to the steering shaft 3 at a position separate from the second pulley 22. The steering sensor 30 may have a detection shaft 30a extending in the same direction as the steering shaft 3 (the up-and-down direction in FIG. 2), and a second gear 32 may be fixed to this detection shaft 30a. These gears 31, 32 may be aligned in the front-to-rear direction, and the teeth of these gears 31, 32 may directly mesh with each other. When the steering shaft 3 rotates, the detection shaft 30a rotates by an angle corresponding to the gear ratio of the gears 31, 32. This allows the steering sensor 30 to detect the rotation angle of the steering shaft 3 in the circumferential direction. In other words, the steering sensor 30 can detect the rotation angle of the steering wheel 2.

[0033] Fig. 3 is a block diagram showing hardware of the steering control system 10. In addition to the electric motor 11, the transmission mechanism 20, and the steering sensor 30 shown in Fig. 2, the steering control system 10 may include a battery 15, a motor drive device 16, a weight sensor 40, a vehicle speed sensor 50, an inclination sensor 60, and a control device 100. The steering control system 10 may also include a pedal force sensor that detects the pedal force applied by the driver to the pedal 9a.

[0034] The control device 100 has a calculation device such as a CPU (Central Processing Unit) and a storage device 100M that stores programs and maps for executing calculation processing in the calculation device. The storage device 100M may be a storage medium such as a RAM (Random Access Memory) or a ROM (Read Only Memory).

[0035] The battery 15 supplies power to the motor drive device 16. The battery 15 may also supply power to a device or component (for example, the control device 100) different from the motor drive device 16. The motor drive device 16 receives power from the battery 15 and supplies power to the electric motor 11 according to an assist torque determined by the control device 100, which will be described later. The control device 100 determines the assist torque for applying an appropriate torque from the electric motor 11 to the steering shaft 3 based on values ​​detected by the steering sensor 30, the weight sensor 40, the vehicle speed sensor 50, and the tilt sensor 60, as will be described later.

[0036] As described above, the steering sensor 30 detects the rotation angle of the steering wheel 2. The weight sensor 40 detects the weight of the two-wheeled vehicle 1. The weight sensor 40 may detect the weight of luggage carried on the two-wheeled vehicle 1. The weight sensor 40 may also detect the weight of luggage or a person carried on the front basket 6 or a child seat of the two-wheeled vehicle 1.

[0037] The vehicle speed sensor 50 detects the speed (vehicle speed) of the two-wheeled vehicle 1 in the traveling direction (for example, forward). The tilt sensor 60 detects the roll angle and roll angular velocity of the body of the two-wheeled vehicle 1. The roll angle of the body of the two-wheeled vehicle 1 is the angle in the circumferential direction around an axis along the front-to-rear direction of the body, and is the tilt angle of the body to the left or right. The roll angular velocity of the body of the two-wheeled vehicle 1 is the amount of displacement of the roll angle per unit time.

[0038] The vehicle speed sensor 50 may be, for example, a magnetic rotation sensor attached to the front wheel 7a or the rear wheel 7b. In this case, the vehicle speed sensor 50 outputs a pulse signal when a magnet attached to a part of the outer periphery of the front wheel 7a or the rear wheel 7b reaches the sensor body. The tilt sensor 60 may be an inertial measurement unit (IMU) attached to the frame 4 of the vehicle body.

[0039] [3. Details of roll angle and roll angular velocity] Fig. 4 is a diagram showing an example of the roll angle and roll angular velocity when maneuvering the two-wheeled vehicle 1. Fig. 4 (1) shows a state in which the two-wheeled vehicle 1 is traveling straight ahead, Fig. 4 (2) shows a state in which the two-wheeled vehicle 1 is turning to the right from the state (1), and Fig. 4 (3) shows a state in which the two-wheeled vehicle 1 is returning to a state of traveling straight ahead from the state (2).

[0040] In (1) of FIG. 4, the two-wheeled vehicle 1 is traveling straight, and the vehicle body is in a vertical posture (neutral posture) with no tilting to the left or right. In this case, the roll angle θ and roll angular velocity Δθ ​​of the vehicle body may be 0. In the following description, a roll angle when the vehicle body is tilting to the right is indicated by a positive value, and a roll angle when the vehicle body is tilting to the left is indicated by a negative value. Furthermore, a roll angular velocity at the timing when the vehicle body is tilting to the right is indicated by a positive value, and a roll angular velocity at the timing when the vehicle body is tilting to the left is indicated by a negative value.

[0041] As shown in FIG. 4 (2), when the two-wheeled vehicle 1 turns right, the body tilts to the right. The roll angle θ of the body here may be θ1 (θ1>0). Also, as shown in FIG. 4 (3), when the two-wheeled vehicle 1 returns from a state of turning right to a state of going straight, the angle of tilt of the body to the right becomes shallower than in the state of (2). The roll angle θ of the body here may be θ2 (0<θ2<θ1).

[0042] As shown in (1) and (2) of Fig. 4, the roll angular velocity Δθ ​​at the timing when the vehicle body tilts to the right may be a (a>0). Also, as shown in (2) of Fig. 4, the roll angular velocity Δθ ​​at the timing when the vehicle body is tilting to the right and there is no further tilting to the left or right from that state (i.e., the timing when the two-wheeled vehicle 1 continues to turn to the right) may be 0. Also, as shown in (2) and (3) of Fig. 4, the roll angular velocity Δθ ​​at the timing when the two-wheeled vehicle 1 returns from a state of turning to the right to a state of traveling straight may be -b (-b<0).

[0043] The inventors of the present application measured the roll angular velocity and the load torque while the two-wheeled vehicle was traveling and found that there is a high correlation between them. The measured "load torque" is the torque generated on the steering shaft 3 when the driver operates the steering wheel 2 of the two-wheeled vehicle 1 that does not have a steering control system 10. The load torque is detected, for example, by a torque sensor attached to or around the steering shaft 3.

[0044] FIG. 5A is a graph showing the correlation between the actually measured roll angular velocity and the load torque. In FIG. 5A, the vertical axis represents the correlation coefficient between the roll angular velocity and the load torque, and the horizontal axis represents the time difference between the timing at which the roll angular velocity is detected and the timing at which the load torque is detected. For example, the correlation coefficient at a time difference of 0 (value of 0 on the horizontal axis) is the correlation coefficient between the roll angular velocity and the load torque detected at the same timing. Furthermore, the correlation coefficient at a time difference of −100 milliseconds (value of −100 on the horizontal axis) is the correlation coefficient between the roll angular velocity detected 100 milliseconds after the timing at which the load torque is detected and the load torque. The correlation coefficient at a time difference of +100 milliseconds (value of +100 on the horizontal axis) is the correlation coefficient between the roll angular velocity detected 100 milliseconds before the timing at which the load torque is detected and the load torque.

[0045] From this measurement, it was found that the correlation coefficient between the roll angular velocity and the load torque is essentially "1" when the time difference between the timing at which the roll angular velocity is detected and the timing at which the load torque is detected is 0, as shown in FIG. 5A. From this, it can be said that the roll angular velocity essentially indicates the load torque. In other words, it can be said that the change and magnitude of the roll angular velocity essentially indicate the change and magnitude of the load torque.

[0046] Therefore, as will be explained later, the steering control system 10 applies a torque to the steering shaft 3, the magnitude of which corresponds to the roll angular velocity and directed in a direction corresponding to the roll angular velocity. As shown in Fig. 5A, the timing at which the load torque changes substantially coincides with the timing at which the roll angular velocity changes. Therefore, the steering control system 10 makes it possible to apply a torque to the steering shaft 3 to reduce or cancel out the load torque at the timing at which the load torque increases (the timing at which the driver applies torque to the steering 2).

[0047] The inventors of the present application measured the roll angle and the load torque while the two-wheeled vehicle was running and found that the correlation therebetween is lower than the correlation between the roll angular velocity and the load torque.

[0048] FIG. 5B is a graph showing the correlation between the actually measured roll angle and the load torque. In FIG. 5B, the vertical axis represents the correlation coefficient between the roll angle and the load torque, and the horizontal axis represents the time difference between the timing at which the roll angle is detected and the timing at which the load torque is detected. In FIG. 5B, for example, the correlation coefficient at a time difference of 0 (value of 0 on the horizontal axis) is the correlation coefficient between the roll angle and the load torque detected at the same timing. Furthermore, the correlation coefficient at a time difference of −100 milliseconds (value of −100 on the horizontal axis) is the correlation coefficient between the roll angle detected 100 milliseconds after the timing at which the load torque is detected and the load torque. The correlation coefficient at a time difference of +100 milliseconds (value of +100 on the horizontal axis) is the correlation coefficient between the roll angle detected 100 milliseconds before the timing at which the load torque is detected and the load torque.

[0049] 5B, the correlation between the roll angular velocity and the load torque is closest to 1 when the time difference between the timing at which the roll angular velocity is detected and the timing at which the load torque is detected is between -100 and -200. This means that changes in the roll angle occur slightly later than changes in the load torque.

[0050] [4. Functions of the control device] Fig. 6 is a functional block diagram showing functions of the control device 100 of the steering control system 10. As shown in Fig. 6, the control device 100 may have, as functions, a roll angular velocity acquisition unit 110, a weight acquisition unit 120, a vehicle speed acquisition unit 130, a turning value acquisition unit 140, an assist torque calculation unit 150, an assist torque correction unit 160, a resistance torque calculation unit 170, a resistance torque correction unit 180, and an output torque calculation unit 190.

[0051] The roll angular velocity acquisition unit 110 acquires the roll angular velocity of the two-wheeled vehicle 1 detected by the tilt sensor 60. The vehicle speed acquisition unit 130 acquires the vehicle speed detected by the vehicle speed sensor .

[0052] The weight acquisition unit 120 may acquire the weight of the two-wheeled vehicle 1 detected by the weight sensor 40 and / or the weight of luggage loaded on the two-wheeled vehicle 1 (for example, the weight of luggage in the front basket 6 or a child in a child seat). The weight acquisition unit 120 may acquire the weight of luggage loaded on the two-wheeled vehicle 1 by subtracting the weight of the two-wheeled vehicle 1 when no luggage is loaded from the current weight of the two-wheeled vehicle 1 detected by the weight sensor 40. The weight acquisition unit 120 may also calculate the weight of the two-wheeled vehicle 1 based on the ratio of the pedal force on the pedal 9a to the acceleration of the two-wheeled vehicle 1. In this case, the two-wheeled vehicle 1 does not need to have the weight sensor 40.

[0053] The turning value acquisition unit 140 acquires a turning value of the two-wheeled vehicle 1. The turning value is a value indicating the degree of turning of the two-wheeled vehicle 1, and specifically, is the rotation angle of the steering shaft 3 or the roll angle of the vehicle body. The turning value acquisition unit 140 acquires, for example, the rotation angle of the steering wheel 2 detected by the steering sensor 30 as the vehicle turning value. The turning value acquisition unit 140 may also acquire the roll angle of the two-wheeled vehicle 1 detected by the tilt sensor 60 as the turning value. In this case, the steering control system 10 does not need to have the steering sensor 30 and gears 31 and 32 shown in FIG. 2.

[0054] [4-1. Calculating auxiliary torque] The assist torque calculation unit 150 calculates the assist torque, which is a torque with a magnitude corresponding to the roll angular velocity acquired by the roll angular velocity acquisition unit 110. As described above, the change timing and magnitude of the load torque approximately coincide with the change timing and magnitude of the roll angular velocity. Therefore, by calculating the assist torque with a magnitude corresponding to the roll angular velocity and outputting it to the steering shaft 3, it becomes possible to apply to the steering shaft 3 a torque that reduces or cancels the load torque at the timing when the load torque increases.

[0055] The assist torque calculation section 150 may calculate the assist torque based on a map stored in the storage device 100M. Alternatively, the assist torque calculation section 150 may calculate the assist torque based on a predetermined calculation formula.

[0056] FIG. 7 is a diagram showing an example of a map stored in the storage device 100M. In the map shown in FIG. 7, the horizontal axis represents the roll angular velocity, with positive values ​​on the horizontal axis representing the roll angular velocity to the right and negative values ​​representing the roll angular velocity to the left. In addition, in the map shown in the same figure, the vertical axis represents the assist torque, with positive values ​​on the vertical axis representing the assist torque for a right turn and negative values ​​on the vertical axis representing the assist torque for a left turn. The assist torque calculation unit 150 may refer to the map shown in FIG. 7 and calculate the assist torque according to the roll angular velocity acquired by the roll angular velocity acquisition unit 110.

[0057] The assist torque calculation unit 150 calculates an assist torque in a direction corresponding to the roll angular velocity of the two-wheeled vehicle 1. For example, when the tilt sensor 40 detects a roll angular velocity in the right direction (when the roll angle changes in the right direction), the assist torque calculation unit 150 calculates an assist torque in a direction that rotates the steering shaft 3 to the right. For example, as shown in (1) and (2) in FIG. 4, when the roll angular velocity Δθ ​​is a positive value and indicates a change in the roll angle to the right, the assist torque calculation unit 150 calculates an assist torque for applying a force to rotate the steering shaft 3 to the right.

[0058] Conversely, when the tilt sensor 40 detects a roll angular velocity in the left direction (when the roll angle changes to the left), the assist torque calculation unit 150 calculates an assist torque in a direction that rotates the steering shaft 3 to the left. For example, as shown in (2) and (3) in FIG. 4, when the direction corresponding to the roll angular velocity Δθ ​​is a negative value, indicating a change in the roll angle to the left, the assist torque calculation unit 150 calculates an assist torque for applying a force to rotate the steering shaft 3 to the left.

[0059] When a roll angular velocity in the left direction is detected while the vehicle body is tilting rightward from a vertical position, the assist torque calculation unit 150 calculates an assist torque in a direction to turn the steering shaft 3 leftward. When a roll angular velocity in the right direction is detected while the vehicle body is tilting leftward from a vertical position, the assist torque calculation unit 150 calculates an assist torque in a direction to rotate the steering shaft 3 rightward. For example, as shown in (2) and (3) in FIG. 4, when a roll angular velocity Δθ ​​in the left direction is detected while the vehicle body is tilting rightward, the assist torque calculation unit 150 calculates an assist torque in a direction to rotate the steering shaft 3 leftward.

[0060] The map shown in FIG. 7 is designed so that the assist torque (absolute value of the assist torque) calculated by the assist torque calculation unit 150 increases as the roll angular velocity (absolute value of the roll angular velocity) increases when the absolute value of the roll angular velocity is within a range (between +xa and +xb and between -xa and -xb in FIG. 7) greater than a predetermined value (for example, 0). For example, the assist torque calculated when the roll angular velocity increases in a positive direction (to the right in FIG. 7) increases in the positive direction (upward in FIG. 7), i.e., in the direction of clockwise rotation. Similarly, the assist torque calculated when the roll angular velocity increases in a negative direction (to the left in FIG. 7) increases in the negative direction (downward in FIG. 7), i.e., in the direction of counterclockwise rotation. In this way, for example, when the two-wheeled vehicle 1 in a vertical position tilts to turn and a large roll angular velocity is acquired by the roll angular velocity acquisition unit 110, it becomes possible to apply a large assist torque to the steering shaft 3. In other words, it becomes possible to apply a large assist torque to the steering shaft 3 at the timing when the steering 2 needs to be operated. This effectively reduces the force required by the driver to operate the steering wheel 2.

[0061] Furthermore, as shown in the map of Fig. 7, when the roll angular velocity exceeds a threshold value (+xb or -xb in Fig. 7), the increase in assist torque (absolute value of assist torque) with an increase in roll angular velocity (absolute value of roll angular velocity) may be smaller than when the roll angular velocity is smaller than the threshold value. In this way, it is possible to prevent excessive assist torque from being applied to the steering shaft 3. As shown in Fig. 7, when the roll angular velocity exceeds a threshold value (xb or -xb in Fig. 7), the assist torque (absolute value of assist torque) may be constant regardless of an increase in the roll angular velocity (absolute value of roll angular velocity).

[0062] 7 is designed so that when the roll angular velocity is within a range that includes 0 (within the range of -xa to +xa in FIG. 7) (when the absolute value of the roll angular velocity is lower than the threshold value (xa)), the assist torque calculated by the assist torque calculation unit 150 becomes substantially 0. In this way, by providing a so-called dead zone, it is possible to prevent the assist torque from being applied to the steering shaft 3 due to minute changes in the roll angular velocity.

[0063] When the dimensions and weight of the vehicle body are fixed, the steering rotation angle (self-steering angle) at which the vehicle posture is stabilized when the two-wheeled vehicle is turning is uniquely determined by the roll angle of the vehicle body. Therefore, when the roll angle changes, the self-steering angle also changes. The assist torque determined in FIG. 7 is, for example, the torque required to achieve the amount of change in the self-steering angle required for the change in the roll angle per unit time (i.e., the roll angular velocity). Therefore, when such assist torque is applied to the steering shaft 3 from the actuator (electric motor 11 and transmission mechanism 20), stable turning (turning while maintaining the self-steering angle) can be achieved while reducing the steering force required by the driver to operate the steering wheel 2.

[0064] The control device 100 may calculate the assist torque based on the roll angular velocity acquired by the roll angular velocity acquisition unit 110 and a parameter other than the roll angular velocity. For example, the assist torque correction unit 160 shown in Fig. 6 may correct the assist torque calculated by the assist torque calculation unit 150 based on a value other than the roll angular velocity acquired by the roll angular velocity acquisition unit 110.

[0065] The value different from the roll angular velocity may be the weight of the two-wheeled vehicle 1 or the weight of luggage carried on the two-wheeled vehicle 1. The control device 100 may calculate the assist torque based on, for example, the roll angular velocity and the weight of the two-wheeled vehicle 1 and / or the weight of luggage carried on the two-wheeled vehicle 1. In this case, the assist torque correction unit 160 may correct the assist torque calculated by the assist torque calculation unit 150 based on the weight (the weight of the two-wheeled vehicle 1 and / or the weight of luggage carried on the two-wheeled vehicle 1).

[0066] When the vehicle or the luggage carried on the vehicle is heavy, a large force is required to operate the steering wheel 2. For this reason, the assist torque calculated by the assist torque calculation unit 150 (assist torque corrected by the assist torque correction unit 160) may increase as the weight of the two-wheeled vehicle 1 or the weight of luggage carried on the two-wheeled vehicle 1 increases. In this way, the force required by the driver to operate the steering wheel 2 can be reduced more effectively.

[0067] The value different from the roll angular velocity may be the vehicle speed. The control device 100 may calculate the assist torque based on, for example, the roll angular velocity acquired by the roll angular velocity acquisition unit 110 and the vehicle speed acquired by the vehicle speed acquisition unit 130. In this case, the assist torque correction unit 160 may correct the assist torque calculated by the assist torque calculation unit 150 based on the vehicle speed.

[0068] Fig. 8 is a diagram showing an example of a map stored in the storage device 100M. In the map shown in Fig. 8, the horizontal axis represents vehicle speed, and the vertical axis represents correction amount. The assist torque correction unit 160 may refer to the map shown in Fig. 8 and calculate the correction amount of the assist torque according to the vehicle speed acquired by the vehicle speed acquisition unit 130.

[0069] The correction amount shown in Fig. 8 may be, for example, the ratio between the assist torque before and after correction. That is, the assist torque correcting unit 160 may multiply the assist torque calculated by the assist torque calculating unit 150 by the correction amount (ratio) obtained from Fig. 8. Alternatively, the memory device 100M may store a map indicating the correction amount to be added to (or subtracted from) the assist torque calculated by the assist torque calculating unit 150.

[0070] When the two-wheeled vehicle 1 is traveling at high speed, the gyro effect keeps the traveling direction of the two-wheeled vehicle 1 constant. In this case, a large force is required to operate the steering wheel 2 in order to change the traveling direction of the two-wheeled vehicle 1. For this reason, the assist torque calculated by the control device 100 may increase as the vehicle speed increases. The map shown in FIG. 8 is designed so that when the vehicle speed is within a predetermined range (the range from xc to xd in FIG. 8), the amount of correction to the assist torque increases as the vehicle speed increases. In this way, the force required by the driver to operate the steering wheel 2 can be more effectively reduced.

[0071] When the vehicle speed exceeds a predetermined threshold (xd in FIG. 8), the correction amount of the assist torque may be constant regardless of an increase in the vehicle speed. When the vehicle speed is below a predetermined threshold (xc in FIG. 8) or when no pedal force is applied to the pedal 9a, the assist torque calculated by the control device 100 may be set to 0.

[0072] The control device 100 may calculate the assist torque based on the shape of the two-wheeled vehicle 1. The two-wheeled vehicle 1 may also have a weight sensor 40 that detects the weight on the front side (for example, the weight of the front basket 6 or child seat) and a weight sensor that detects the weight on the rear side (for example, the weight of a rear basket attached behind the saddle 8). In this case, the control device 100 may calculate the assist torque based on the weights detected by the two weight sensors.

[0073] 6, the assist torque calculated by the assist torque calculation unit 150 is corrected by the assist torque correction unit 160. However, the process for calculating the assist torque is not limited to this.

[0074] For example, the assist torque calculation unit 150 may directly calculate the assist torque based on the roll angular velocity and the vehicle speed. In this case, the assist torque calculation unit 150 may use a three-dimensional or higher dimensional map (a map associating the roll angular velocity, the vehicle speed, and the assist torque) stored in the storage device 100M. Similarly, the assist torque calculation unit 150 may directly calculate the assist torque based on the roll angular velocity and the weight. In this case, the assist torque calculation unit 150 may use a three-dimensional or higher dimensional map (a map associating the roll angular velocity, the weight, and the assist torque) stored in the storage device 100M. In this way, the assist torque calculation unit 150 may directly calculate the assist torque based on parameters other than the roll angular velocity (such as the vehicle speed or the weight).

[0075] [4-2. Calculating the resistance torque] The resistance torque calculation unit 170 calculates the resistance torque, which is a torque in the opposite direction to the direction in which the steering shaft 3 is rotating from the neutral position. The resistance torque calculated by the resistance torque calculation unit 170 has a magnitude corresponding to the vehicle turning value acquired by the turning value acquisition unit 140. As described above, the vehicle turning value may be the roll angle of the two-wheeled vehicle 1 or the rotation angle of the steering shaft 3. In this way, it is possible to apply a resistance torque to the steering shaft 3 so that the rotation angle of the steering shaft 3 does not become large. Furthermore, it is possible to apply a resistance torque corresponding to the vehicle turning value to the steering shaft 3 without restricting the range of the angular velocity or the range of the angular position of the steering shaft 3. For example, the driver can quickly turn the steering shaft 3 to the left when the vehicle is turning right.

[0076] The resistance torque calculation unit 170 may calculate the resistance torque based on a map stored in the storage device 100M, similar to the assist torque calculation unit 150. Alternatively, the resistance torque calculation unit 170 may calculate the resistance torque based on a predetermined calculation formula.

[0077] FIG. 9 is a diagram showing an example of a map stored in the storage device 100M. In the map shown in FIG. 9, the horizontal axis represents the vehicle turning value. Positive values ​​on the horizontal axis represent the vehicle turning value indicating a turn to the right (the roll angle of the two-wheeled vehicle 1 or the rotation angle of the steering shaft 3 to the right), and negative values ​​on the horizontal axis represent the vehicle turning value indicating a turn to the left. In addition, in the map shown in the same figure, the vertical axis represents the resistance torque. Positive values ​​on the vertical axis represent the resistance torque in the direction of rotating the steering shaft 3 to the right, and negative values ​​on the vertical axis represent the resistance torque in the direction of rotating the steering shaft 3 to the left. The resistance torque calculation unit 170 may refer to the map shown in FIG. 9 and calculate the resistance torque according to the vehicle turning value acquired by the turning value acquisition unit 140.

[0078] The resistance torque calculation unit 170 calculates a resistance torque in a direction opposite to the direction indicated by the vehicle turning value acquired by the turning value acquisition unit 140. For example, when the two-wheeled vehicle 1 is tilted to the right, in other words, when the steering shaft 3 is rotating to the right from the neutral position, the resistance torque calculation unit 170 calculates a resistance torque in a direction that rotates the steering shaft 3 to the left. Conversely, when the two-wheeled vehicle 1 is tilted to the left, in other words, when the steering shaft 3 is rotating to the left from the neutral position, the resistance torque calculation unit 170 calculates a resistance torque in a direction that rotates the steering shaft 3 to the right.

[0079] The map shown in FIG. 9 is designed so that, within a range where the absolute value of the vehicle turning value is greater than 0 (between +xe and +xf and between -xe and -xf in the example of FIG. 9), the resistance torque (absolute value of the resistance torque) calculated by the resistance torque calculation unit 170 increases as the vehicle turning value (absolute value of the vehicle turning value) increases. For example, as the vehicle turning value increases in a positive direction, the resistance torque increases in a negative direction (downward in FIG. 9), i.e., in the direction of leftward rotation. That is, as the roll angle increases in the rightward direction or as the steering axis increases in the direction of rightward rotation, the resistance torque increases in the direction of leftward rotation. Conversely, as the vehicle turning value increases in a negative direction, the resistance torque increases in a positive direction (upward in FIG. 9), i.e., in the direction of rightward rotation. That is, as the roll angle increases in the leftward direction or as the steering axis increases in the direction of leftward rotation, the resistance torque increases in the direction of rightward rotation. By doing this, for example, when the vehicle is tilted significantly to the right or the steering wheel 2 is rotated significantly in the right direction from the neutral position, the driver can rotate the steering shaft 3 more quickly to the left.

[0080] 9 is designed so that when the vehicle turning value exceeds a threshold value (+xf or -xf in FIG. 9), the increase in resistance torque due to an increase in the vehicle turning value is smaller than when the vehicle turning value is smaller than the threshold value. This makes it possible to prevent excessive resistance torque from being applied to the steering shaft 3. As shown in FIG. 9, in the range where the vehicle turning value exceeds the threshold value (xf or -xf in FIG. 9), the resistance torque may be constant regardless of an increase in the vehicle turning value.

[0081] 9 is designed so that the resistance torque becomes substantially 0 when the vehicle turning value is within a range including 0 (within the range of -xe to +xe in FIG. 9) (when the absolute value of the vehicle turning value is lower than the threshold value (xe)). By providing a dead zone in this way, it is possible to prevent the resistance torque from being applied to the steering shaft 3 due to minute changes in the vehicle turning value.

[0082] The control device 100 may calculate the resistance torque based on the vehicle turning value acquired by the turning value acquisition unit 140 and a parameter other than the vehicle turning value. For example, the resistance torque correction unit 180 shown in Fig. 6 may correct the assist torque calculated by the resistance torque calculation unit 170 based on a value other than the vehicle turning value.

[0083] The value different from the vehicle turning value may be, for example, the weight of the two-wheeled vehicle 1 or the weight of luggage carried on the two-wheeled vehicle 1. The control device 100 may calculate the resistance torque based on, for example, the vehicle turning value and the weight of the two-wheeled vehicle 1 and / or the weight of luggage carried on the two-wheeled vehicle 1. In this case, the resistance torque correction unit 180 may correct the resistance torque calculated by the resistance torque calculation unit 170 based on the weight (the weight of the two-wheeled vehicle 1 and / or the weight of luggage carried on the two-wheeled vehicle 1). This makes it possible to more effectively reduce the force required by the driver to operate the steering wheel 2.

[0084] The value different from the vehicle turning value may be, for example, the vehicle speed. The control device 100 may calculate the resistance torque based on, for example, the vehicle turning value and the vehicle speed acquired by the vehicle speed acquisition unit 130. In this case, the resistance torque correction unit 180 may correct the resistance torque calculated by the resistance torque calculation unit 170 based on the vehicle speed.

[0085] Fig. 10 is a diagram showing an example of a map stored in the storage device 100M. In the map shown in Fig. 10, the horizontal axis represents the vehicle speed, and the vertical axis represents the correction amount. The resistance torque correction unit 180 may refer to the map shown in Fig. 10 and calculate the correction amount of the resistance torque according to the vehicle speed acquired by the vehicle speed acquisition unit 130.

[0086] The correction amount shown in Fig. 10 may be, for example, the ratio between the resistance torque before and after correction. That is, the assist torque correction unit 180 may multiply the resistance torque calculated by the resistance torque calculation unit 170 by the correction amount (ratio) obtained from Fig. 10. Alternatively, the memory device 100M may store a map indicating the correction amount to be added to (or subtracted from) the resistance torque calculated by the resistance torque calculation unit 170.

[0087] When the vehicle speed of the two-wheeled vehicle 1 is high, a gyroscopic effect occurs in the two-wheeled vehicle 1, making it difficult for the steering shaft 3 to rotate (steering wheel 2 to wobble) due to the weight of a load on the front basket 6, a child seat, or the like. For this reason, the map shown in FIG. 10 is designed so that the correction amount for the resistance torque when the vehicle speed is high (first vehicle speed range) is smaller than the correction amount for the resistance torque when the vehicle speed is medium (second vehicle speed range). In FIG. 10, the high speed (first vehicle speed range) is a vehicle speed range equal to or greater than vehicle speed xj. Also, in FIG. 10, the medium speed (second vehicle speed range) is a vehicle speed range lower than the first vehicle speed range, and in the example shown in FIG. 10, is a vehicle speed range equal to or greater than vehicle speed xh and equal to or less than vehicle speed xi.

[0088] It is preferable that the resistance torque in the direction opposite to the rotation direction of the steering shaft 3 is made larger when the vehicle speed of the two-wheeled vehicle 1 is medium speed compared to when the vehicle speed is high. For this reason, the map shown in Fig. 10 is designed so that the correction amount of the resistance torque is larger when the vehicle speed is medium speed (within the range of xh to xi in Fig. 10) compared to when the vehicle speed is high.

[0089] Furthermore, when the vehicle speed of the two-wheeled vehicle 1 is low, the two-wheeled vehicle 1 can turn with a small turning radius by rotating the steering wheel 2 and the steering shaft 3 greatly. In this case, it is preferable that the resistance torque calculated by the control device 100 is small so as not to hinder the rotation of the steering shaft 3. For this reason, the map shown in Fig. 10 is designed so that the correction amount for the resistance torque is small when the vehicle speed is low (when the vehicle speed is below xg in Fig. 10).

[0090] Unlike the example shown in FIG. 10, in the map stored in the memory device 100M, when the vehicle speed is low, the correction amount of the resistance torque may be designed to be larger than when the vehicle speed is high, just as when the vehicle speed is medium.

[0091] The control device 100 may calculate the resistance torque based on the shape of the two-wheeled vehicle 1. The control device 100 may also calculate the resistance torque based on the weights detected by the weight sensor 40 that detects the weight of the front side (for example, the front basket 6 or the child seat) and the weight sensor that detects the weight of the rear side (for example, a rear basket attached behind the saddle 8).

[0092] 10, the resistance torque calculated by the resistance torque calculation unit 170 is corrected by the resistance torque correction unit 180. However, the process for calculating the resistance torque is not limited to this.

[0093] For example, the resistance torque calculation unit 170 may directly calculate the resistance torque based on the vehicle turning value and the vehicle speed. In this case, the resistance torque calculation unit 170 may use a three-dimensional or higher dimensional map (a map associating the vehicle turning value, the vehicle speed, and the resistance torque) stored in the storage device 100M. Similarly, the resistance torque calculation unit 170 may directly calculate the resistance torque based on the vehicle turning value and the weight. In this case, the resistance torque calculation unit 170 may use a three-dimensional or higher dimensional map (a map associating the vehicle turning value, the weight, and the resistance torque) stored in the storage device 100M. In this way, the resistance torque calculation unit 170 may directly calculate the assist torque based on parameters other than the roll angular velocity (such as the vehicle speed or the weight).

[0094] [4-3. Calculating output torque] The output torque calculation unit 190 calculates the output torque to be applied to the steering shaft 3 based on the assist torque calculated by the assist torque calculation unit 150 and the assist torque correction unit 160 and the resistance torque calculated by the resistance torque calculation unit 170 and the resistance torque correction unit 180. The output torque calculation unit 190 calculates the output torque by adding or subtracting the assist torque from the resistance torque.

[0095] When the direction of rotation of the steering shaft 3 due to the assist torque and the direction of rotation of the steering shaft 3 due to the resistance torque are opposite to each other, the output torque calculation unit 190 calculates the output torque based on the difference between the assist torque and the resistance torque (the difference between the absolute value of the assist torque and the absolute value of the resistance torque). The output torque calculation unit 190 may calculate the difference between the absolute value of the assist torque and the absolute value of the resistance torque as the output torque.

[0096] When the resistance torque (absolute value of the resistance torque) is smaller than the assist torque (absolute value of the assist torque), the output torque calculation unit 190 calculates an output torque in the same direction as the torque acting on the steering shaft 3 due to the driver's operation. For example, as shown in (1) and (2) in Fig. 4, when the two-wheeled vehicle 1 is tilted to the right from a vertical position and a roll angular velocity is occurring, the output torque calculation unit 190 calculates a right rotation output torque (i.e., assist torque) as the torque to be applied to the steering shaft 3 in order to assist the driver's operation of the steering wheel 2.

[0097] Furthermore, when the resistance torque (absolute value of the resistance torque) is greater than the assist torque (absolute value of the assist torque), the output torque calculation unit 190 calculates an output torque in the opposite direction to the direction in which the steering shaft 3 is rotating from the neutral position. For example, as shown in (2) of FIG. 4, when the two-wheeled vehicle 1 is tilted to the right and no roll angular velocity is occurring, the output torque calculation unit 190 calculates a counterclockwise output torque as the torque to be applied to the steering shaft 3. This output torque makes it possible to apply an output torque (i.e., resistance torque) to the steering shaft 3 so that the rotation angle of the steering shaft 3 does not increase.

[0098] Furthermore, when the direction of rotation of the steering shaft 3 due to the assist torque is the same as the direction of rotation of the steering shaft 3 due to the resistance torque, the output torque calculation unit 190 may calculate the output torque based on the sum of the assist torque and the resistance torque. The output torque calculation unit 190 may calculate the sum of the assist torque and the resistance torque as the output torque.

[0099] For example, as shown in (2) and (3) of FIG. 4, when a roll angular velocity in the left direction (a change in the roll angle toward a vertical position) is detected while the vehicle body is tilted to the right, the rotation direction of the assist torque and the resistance torque with respect to the steering shaft 3 coincide. Here, the output torque calculation unit 190 may calculate the output torque based on the sum of the assist torque and the resistance torque (the sum of the absolute value of the assist torque and the absolute value of the resistance torque). In this way, a large output torque can be calculated toward the neutral position of the steering wheel 2 when the two-wheeled vehicle 1 finishes turning (when the vehicle body is returned from a tilted position to a vertical position).

[0100] An upper limit may be set for the output torque calculated by the output torque calculation unit 190. For example, it is preferable that the output torque calculated by the output torque calculation unit 190 is of a magnitude that does not eliminate the roll (tilt) of the body of the two-wheeled vehicle 1. In this way, it is possible to prevent the steering wheel 2 from automatically returning to the neutral position against the driver's intention when the two-wheeled vehicle 1 is turning. This makes it possible to keep the rotation angle of the steering shaft 3 constant during turning as intended by the driver, and to maintain a so-called self-steering state when the two-wheeled vehicle 1 is turning.

[0101] The output torque is preferably smaller than the torque acting on the steering shaft 3 due to the vehicle's load weight (load weight of the front basket 6, child seat, etc.). The output torque may be smaller than 10 Newton meters (Nm). More preferably, the output torque may be smaller than 7 Newton meters (Nm). 10 Newton meters (Nm) is smaller than the torque that a typical driver can exert. Therefore, by setting the output torque to a value of 10 Newton meters (Nm) or less, the driver can rotate the steering wheel 2 against the torque acting on the steering shaft 3 by the actuator (electric motor 11 and transmission mechanism 20).

[0102] The control device 100 controls the actuator (more specifically, the electric motor 11) based on the output torque calculated by the output torque calculation unit 190. More specifically, the control device 100 outputs a command value (torque command value) corresponding to the output torque calculated by the output torque calculation unit 190 to the motor drive device 16. The motor drive device 16 then supplies a current corresponding to the torque command value to the electric motor 11. This drives the electric motor 11 and the transmission mechanism 20, and a torque of a magnitude and direction corresponding to the output torque is applied to the steering shaft 3.

[0103] [5. Flowchart] 11 is a flowchart showing an example of a control process executed by the steering control system 10. The steering control system 10 may repeatedly execute the control process shown in FIG.

[0104] As shown in Fig. 11, the control device 100 may determine whether or not the two-wheeled vehicle 1 is being pushed while walking (step S101). The process of determining whether or not the two-wheeled vehicle 1 is being pushed while walking can be performed, for example, based on whether or not a pedaling force applied by the driver to the pedal 9a is detected by a sensor (pedaling force sensor) and the vehicle speed. For example, if the driver is not applying a pedaling force to the pedal 9a and the vehicle speed is greater than 0, the control device 100 determines that the two-wheeled vehicle 1 is being pushed while walking, and if the driver is applying a pedaling force to the pedal 9a, the control device 100 determines that the two-wheeled vehicle 1 is not being pushed while walking.

[0105] If it is determined that the two-wheeled vehicle 1 is not being pushed while walking (N in step S101), the control device 100 may calculate both the assist torque and the resistance torque. In this case, the assist torque calculation unit 150 calculates the assist torque based on the roll angular velocity (step S102). Then, the resistance torque calculation unit 170 calculates the resistance torque based on the vehicle turning value (the roll angle of the two-wheeled vehicle 1 or the rotation angle of the steering shaft 3) (step S103). In the process of step S102, the assist torque correction unit 160 may correct the assist torque calculated by the assist torque calculation unit 150 based on the vehicle speed, weight, etc. In the process of step S103, the resistance torque correction unit 180 may correct the resistance torque calculated by the resistance torque calculation unit 170 based on the vehicle speed, weight, etc. Note that the order of executing the processes of steps S102 and S103 may be reversed, or the processes of steps S102 and S103 may be executed simultaneously.

[0106] When it is determined that the two-wheeled vehicle 1 is in a state of being pushed while walking (Y in step S101), the control device 100 may calculate only the resistance torque (step S103). In this way, it is possible to prevent an assist torque in the opposite direction to the resistance torque from acting on the steering shaft 3.

[0107] Next, the control device 100 calculates the output torque (step S104) and controls the electric motor 11 based on this output torque (step S105). If, as a result of the processes in S101 to S103, it is determined that the two-wheeled vehicle 1 is not being pushed while walking (N in step S101), then in step S104 the output torque calculation unit 190 calculates the output torque based on the assist torque calculated in step S102 and the resistance torque calculated in step S103. On the other hand, if it is determined that the two-wheeled vehicle 1 is being pushed while walking (N in step S101), then in step S104 the output torque calculation unit 190 calculates the output torque based on the resistance torque calculated in step S103. In this case, the output torque calculation unit 190 may calculate the resistance torque calculated in step S103 as the output torque.

[0108] 11, when it is determined that the two-wheeled vehicle 1 is being pushed while walking (Y in step S101), the control device 100 may calculate both the resistance torque and the assist torque, or may calculate only the assist torque. In this case, the output torque may be set to substantially 0 without calculating the resistance torque and the assist torque.

[0109] [6. Summary] (1) As described above, the steering control system 10 includes an actuator including an electric motor 11 that applies torque to the steering shaft 3, which can rotate clockwise and counterclockwise from a neutral position; a steering sensor 30 that detects a vehicle turning value, which is the rotation angle of the steering shaft 3 or the roll angle of the vehicle body; and a control device 100. The control device 100 calculates a resistance torque, which is a torque that is opposite to the direction in which the steering shaft 3 is rotating from the neutral position and corresponds to the vehicle turning value, and controls the actuator based on the resistance torque. This can further improve the operability of the steering 2. For example, the resistance torque can be applied to the steering shaft 3 so that the rotation angle of the steering shaft 3 does not increase. Furthermore, unlike Patent Document 1, the resistance torque corresponding to the vehicle turning value can be applied to the steering shaft 3 without limiting the range of the angular velocity or the range of the angular position of the steering shaft 3. Furthermore, unlike Patent Document 2, the driver can quickly turn the steering shaft 3 counterclockwise when the vehicle is turning right.

[0110] (2) Furthermore, the control device 100 may calculate an assist torque, which is a torque in the same direction as the torque acting on the steering shaft 3 due to the driver's operation, based on the roll angular velocity of the vehicle. The control device 100 may calculate an output torque to be applied to the steering shaft based on the resistance torque and the assist torque. This allows an appropriate torque to be applied to the steering shaft depending on the state of the two-wheeled vehicle 1.

[0111] (3) The control device 100 may calculate the output torque by adding or subtracting the resistance torque and the assist torque.

[0112] (4) When the resistance torque is greater than the assist torque, the control device 100 may calculate an output torque in the opposite direction to the direction in which the steering shaft is rotating from the neutral position. When the resistance torque is smaller than the assist torque, the control device 100 may calculate an output torque in the same direction as the torque acting on the steering shaft due to the driver's operation.

[0113] (5) The absolute value of the resistance torque calculated by the control device 100 may increase as the vehicle turning value increases. This allows torque corresponding to the rotation angle of the steering shaft 3 or the roll angle of the vehicle body to be applied to the steering shaft 3.

[0114] (6) When the absolute value of the vehicle turning value is lower than the threshold value, the resistance torque calculated by the control device 100 may be substantially 0. This makes it possible to prevent the resistance torque from being applied to the steering shaft 3 due to a slight change in the vehicle turning value.

[0115] (7) The output torque calculated by the control device 100 may be smaller than the torque acting on the steering shaft 3 due to the load weight of the vehicle. This can prevent the steering wheel 2 from automatically returning to the neutral position against the driver's intention.

[0116] (8) The output torque calculated by the control device 100 may be smaller than 10 Newton meters (Nm). This allows the driver to rotate the steering wheel 2 against the torque applied to the steering shaft 3 by the actuator.

[0117] (9) In the steering control system 10, the actuator may include a transmission mechanism 20 that transmits torque to the steering shaft 3. The transmission mechanism 20 may include a member that limits the transmission of torque greater than a threshold value. This allows the driver of the two-wheeled vehicle 1 to operate the steering wheel 2 against the torque transmitted to the steering shaft 3.

[0118] (10) The output shaft 11a of the electric motor 11 may be disposed away from the steering shaft 3. The transmission mechanism 20 may include a belt 23 that transmits the torque of the output shaft 11a of the electric motor 11 to the steering shaft 3 as a member that limits the transmission of torque greater than a threshold value. This makes it possible to limit the transmission of torque greater than a threshold value to the steering shaft 3.

[0119] (11) The control device 100 may calculate the resistance torque based on the vehicle turning value and the vehicle speed.

[0120] (12) The control device 100 may calculate the resistance torque so that the resistance torque when the vehicle speed is in a first vehicle speed range is smaller than the resistance torque when the vehicle speed is in a second vehicle speed range that is slower than the first vehicle speed range.

[0121] (13) In any one of the steering control systems (1) to (12), the control device may calculate the resistance torque based on the weight of the vehicle and / or the weight of luggage loaded on the vehicle.

[0122] The present invention is not limited to the above-described embodiment, and various modifications may be made. For example, in the embodiment, an example has been described in which the output torque calculation unit 190 calculates the output torque based on the assist torque and the resistance torque. However, the present invention is not limited to this, and the output torque calculation unit 190 may calculate the output torque based only on the resistance torque calculated by the resistance torque calculation unit 170. For example, the output torque calculation unit 190 may calculate the assist torque corrected by the resistance torque correction unit 180 as the output torque. In this way, too, it is possible to apply output torque (resistance torque) to the steering shaft 3 so that the rotation angle of the steering shaft 3 does not increase.

[0123] In the embodiment, an example has been described in which the assist torque calculation unit 150 calculates the assist torque based on the roll angular velocity detected by the tilt sensor 60. However, the present invention is not limited to this, and the assist torque calculation unit 150 may calculate the assist torque based on torque acquired from a torque sensor that detects the torque acting on the steering shaft 3. Even in this case, by calculating the output torque to be applied to the steering shaft 3 based on the assist torque calculated by the assist torque calculation unit 150 and the resistance torque calculated by the resistance torque calculation unit 170, it becomes possible to apply an appropriate torque (assist torque or resistance torque) to the steering shaft 3 depending on the state of the two-wheeled vehicle 1. [Explanation of symbols]

[0124] 1 Two-wheeled vehicle, 2 Steering, 3 Steering shaft, 4 Frame, 4a Head pipe, 4b Fastener, 6 Front basket, 7a Front wheel, 7b Rear wheel, 8 Saddle, 9a Pedal, 9b Crankshaft, 10 Steering control system, 11 Electric motor, 11a Output shaft, 12 Support base, 15 Battery, 16 Motor drive device, 20 Transmission mechanism, 21 First pulley, 22 Second pulley, 23 Belt, 30 Steering sensor, 30a Detection shaft, 31 First gear, 32 Second gear, 40 Weight sensor, 50 Vehicle speed sensor, 60 Inclination sensor, 100 Control device, 100M Storage device, 110 Roll angular velocity acquisition unit, 120 Weight acquisition unit, 130 Vehicle speed acquisition unit, 140 Turning value acquisition unit, 150 Assist torque calculation unit, 160 Assist torque correction unit, 170 Resistance torque calculation unit, 180 resistance torque correction unit, 190 output torque calculation unit.

Claims

1. an actuator including an electric motor that applies torque to a steering shaft that can rotate right and left from a neutral position; a first sensor for detecting a vehicle turning value, which is a rotation angle of the steering shaft or a roll angle of the vehicle body; a second sensor that detects a pedal force; a control device that determines whether the vehicle is being pushed while walking based on whether a pedal force is being applied to the pedal, and if it is determined that the vehicle is not being pushed while walking, calculates a resistance torque that is a torque that is in the opposite direction to the direction in which the steering shaft is rotating from the neutral position and that corresponds to the vehicle turning value, calculates an assist torque that is a torque in the same direction as the torque that is acting on the steering shaft due to an operation by the driver based on the torque that is acting on the steering shaft or a roll angular velocity of the vehicle body, and calculates an output torque to be applied to the steering shaft based on the resistance torque and the assist torque, and if it is determined that the vehicle is being pushed while walking, calculates the resistance torque, calculates the output torque based on the resistance torque, and controls the actuator based on the output torque; A steering control system for a two-wheeled vehicle.

2. The control device calculates the output torque by adding or subtracting the resistance torque and the assist torque. The steering control system of claim 1 .

3. When the resistance torque is greater than the assist torque, the control device calculates the output torque in the opposite direction to the direction in which the steering shaft is rotating from the neutral position, and when the resistance torque is smaller than the assist torque, the control device calculates the output torque in the same direction as the torque acting on the steering shaft due to the driver's operation. The steering control system of claim 1 .

4. The absolute value of the resistance torque increases as the vehicle turning value increases. The steering control system of claim 1 .

5. When the absolute value of the vehicle turning value is lower than a threshold value, the resisting torque is substantially zero. The steering control system of claim 1 .

6. The output torque is smaller than the torque acting on the steering shaft due to the load weight of the vehicle. The steering control system of claim 1 .

7. The output torque is less than 10 Newton meters (Nm). The steering control system of claim 1 .

8. the actuator includes a transmission mechanism that transmits torque to the steering shaft, the transmission mechanism includes a member that limits transmission of torque greater than a threshold value; The steering control system of claim 1 .

9. an output shaft of the electric motor is disposed away from the steering shaft; The transmission mechanism includes a belt that transmits torque of the output shaft of the electric motor to the steering shaft as a member that limits transmission of torque greater than a threshold value.

9. The steering control system of claim 8.

10. The control device calculates the resistance torque based on the vehicle turning value and the vehicle speed. The steering control system of claim 1 .

11. The control device calculates the resistance torque when the vehicle speed is in a first vehicle speed range so that the resistance torque is smaller than the resistance torque when the vehicle speed is in a second vehicle speed range that is lower than the first vehicle speed range.

11. The steering control system of claim 10.

12. The control device calculates the resistance torque based on the weight of the vehicle and / or the weight of luggage loaded on the vehicle. The steering control system of claim 1 .

Images