Patent Publication Number: US-11046305-B2

Title: Leaning posture control device for leaning vehicle having left and right inclined wheels mounted thereon and leaning vehicle having left and right inclined wheels mounted thereon

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The present application is a continuation-in-part application of International Application No. PCT/JP2017/011862, filed on Mar. 23, 2017, and having the benefit of the earlier filing date of Japanese Application No. 2016-058772, filed Mar. 23, 2016. The content of each of the identified applications is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Technical Field 
     The present teaching relates to a leaning posture control device for controlling a posture of a leaning vehicle having left and right inclined wheels mounted thereon (hereinafter referred to as a “left-right-inclined-wheel-equipped leaning vehicle”) that includes a front wheel and a rear wheel, one of which includes a left wheel and a right wheel, and that turns while being leaned in the turning direction, and also relates to a left-right-inclined-wheel-equipped leaning vehicle on which the leaning posture control device is mounted. 
     Background Art 
     Japanese Patent No. 5580937 (Patent Document 1) discloses a posture control device of a motorcycle including a longitudinal force control section that reduces an absolute value of a longitudinal force of each wheel based on a lateral acceleration and a bank angle. A lateral acceleration is an acceleration in a left direction or in a right direction exerted on a vehicle. A longitudinal force is the sum of forces in a forward direction of the vehicle and a rearward direction of the vehicle exerted on each wheel. The longitudinal force control section acquires a side-slip acceleration of each wheel based on the lateral acceleration and the bank angle, and if the absolute value of the side-slip acceleration exceeds a threshold, reduces the absolute value of a longitudinal force of each wheel. 
     In addition, U.S. Pat. No. 8,123,240 (Patent Document 2) discloses a left-right-inclined-wheel-equipped leaning vehicle including a body frame that can lean in the left direction of the vehicle or in the right direction of the vehicle, and a right front wheel and a left front wheel supported on the body frame. This left-right-inclined-wheel-equipped leaning vehicle includes a lean actuator for controlling the frame to an upright position. 
     CITATION LIST 
     Patent Document 
     
         
         Patent Document 1: Japanese Patent No. 5580937 
         Patent Document 2: U.S. Pat. No. 8,123,240 
       
    
     SUMMARY OF INVENTION 
     The present teaching has an object of providing a leaning posture control device for controlling a leaning posture of a left-right-inclined-wheel-equipped leaning vehicle by a means different from a lean actuator, and a left-right-inclined-wheel-equipped leaning vehicle. 
     An inventor of the present teaching studied to reduce a longitudinal force of each wheel while the left-right-wheel-equipped leaning vehicle is turning with a body frame leaning in the left direction of the vehicle or in the right direction of the vehicle. While the left-right-wheel-equipped leaning vehicle is travelling on a curve, when a resultant force of longitudinal forces of the wheels and a cornering force in the left direction of the vehicle or in the right direction of the vehicle exceeds a maximum allowable level of grip forces of the wheels, the wheels slip. Thus, the allowable level of the cornering force can be increased by reducing the longitudinal forces. 
     The inventor further studied a configuration of the left-right-wheel-equipped leaning vehicle and a behavior during turning. The left-right-wheel-equipped leaning vehicle includes a lean body frame, a right inclined wheel, a left inclined wheel, and another inclined wheel supported by the lean body frame. The lean body frame leans leftward when the vehicle turns leftward, and leans rightward when the vehicle turns rightward. The right inclined wheel, the left inclined wheel, and the other inclined wheel also lean leftward when the vehicle turns leftward, and lean rightward when the vehicle turns rightward. The right inclined wheel and the left inclined wheel are arranged along a left-right direction (lateral direction) of the vehicle. The other inclined wheel is disposed ahead of or behind the right inclined wheel and the left inclined wheel. 
     Through the study, the inventor found that the use of geometrical arrangement of the right inclined wheel, the left inclined wheel, and the other inclined wheel enables a lean of the lean body frame in the left direction or in the right direction to be affected not only by reducing the absolute value of a longitudinal force in the left-right-wheel-equipped leaning vehicle but also by increasing the absolute value. Through further study, the inventor arrived at a configuration in which a force of leaning the lean body frame in the left direction or in the right direction is generated by controlling a torque of at least one of the right inclined wheel or the left inclined wheel while the lean body frame leans, with the use of a physical quantity concerning side-slip of the right inclined wheel, the left inclined wheel, and the other inclined wheel in the left direction or in the right direction. Specifically, the inventor arrived at a configuration in which a torque of at least one of the right inclined wheel or the left inclined wheel is controlled so as to reduce a change in a lean of the lean body frame in the left direction while the lean body frame leans in the left direction or a change in a lean of the lean body frame in the right direction while the lean body frame leans in the right direction, based on a physical quantity concerning side-slip of the right inclined wheel, the left inclined wheel, and the other inclined wheel in the left direction or in the right direction. Based on this finding, the inventor arrived at the following configurations. 
     (First Configuration) 
     A first configuration according to one aspect of the present teaching relates to a leaning posture control device for a left-right-inclined-wheel-equipped leaning vehicle configured to control a leaning posture of the left-right-inclined-wheel-equipped leaning vehicle. The left-right-inclined-wheel-equipped leaning vehicle includes: a lean body frame that leans leftward when the vehicle is turning leftward in a left-right direction of the vehicle, and leans rightward when the vehicle is turning rightward in the left-right direction of the vehicle; a right inclined wheel supported on the lean body frame, the right inclined wheel being leaned leftward when the vehicle is turning leftward in the left-right direction of the vehicle and being leaned rightward when the vehicle is turning rightward in the left-right direction of the vehicle; a left inclined wheel supported on the lean body frame and disposed at a side of the right inclined wheel in the left-right direction of the vehicle, the left inclined wheel being leaned leftward when the vehicle is turning leftward in the left-right direction of the vehicle and being leaned rightward when the vehicle is turning rightward in the left-right direction of the vehicle; and another inclined wheel supported on the lean body frame and disposed ahead of or behind the right inclined wheel and the left inclined wheel in a front-rear direction of the vehicle, the other inclined wheel being leaned leftward when the vehicle is turning leftward in the left-right direction of the vehicle and being leaned rightward when the vehicle is turning rightward in the left-right direction of the vehicle. The leaning posture control device controls a torque of at least one of the right inclined wheel or the left inclined wheel arranged in the left-right direction of the vehicle so as to suppress a change in a lean of the lean body frame in a left direction of the vehicle while the lean body frame is leaned in the left direction or a change in a lean of the lean body frame in a right direction of the vehicle while the lean body frame is leaned in the right direction, based on a physical quantity concerning side-slip, in the left direction of the vehicle or in the right direction of the vehicle, of the right inclined wheel, the left inclined wheel, and the other inclined wheel disposed ahead of or behind the right inclined wheel and the left inclined wheel in the front-rear direction of the vehicle. 
     With the first configuration, the leaning posture control device suppresses a change in a lean of the lean body frame in the left direction or in the right direction by controlling at least one of the right inclined wheel or the left inclined wheel based on a physical quantity concerning side-slip of the right inclined wheel and the left inclined wheel that are arranged along the left-right direction and the other inclined wheel disposed ahead of or behind the right inclined wheel and the left inclined wheel. Accordingly, longitudinal forces of the right inclined wheel and the left inclined wheel are controlled by using geometrical arrangement of the right inclined wheel, the left inclined wheel, and the other inclined wheel so that a lean of the lean body frame in the left direction or in the right direction can be controlled. As a result, a posture of the left-right-wheel-equipped leaning vehicle can be controlled by using a means different from a lean actuator. 
     (Second Configuration) 
     In the first configuration, the leaning posture control device may control a torque of at least one of the right inclined wheel or the left inclined wheel so as to suppress the change in the lean of the lean body frame in the left direction while the lean body frame is leaned in the left direction or the change in the lean body frame in the right direction of the vehicle while the lean body frame is leaned in the right direction, based on the physical quantity concerning side-slip of the right inclined wheel, the left inclined wheel, and the other inclined wheel. 
     (Third Configuration) 
     In the first or second configuration, the physical quantity concerning side-slip of the right inclined wheel, the left inclined wheel, and the other inclined wheel may be a physical quantity concerning displacement of a ground-contact point of each of the right inclined wheel, the left inclined wheel, and the other inclined wheel in the left direction of the vehicle or in the right direction of the vehicle. 
     (Fourth Configuration) 
     In the third configuration, the physical quantity concerning displacement of the ground-contact point of each of the right inclined wheel, the left inclined wheel, and the other inclined wheel in the left direction or in the right direction may be a displacement, a speed, an acceleration, an angular velocity, an angular acceleration, or a value expressed by using at least two of the displacement, the speed, the acceleration, the angular velocity, and the angular acceleration. 
     (Fifth Configuration) 
     A fifth configuration is a configuration of the left-right-inclined-wheel-equipped leaning vehicle including the leaning posture control device having one of the first through fourth configurations. In the left-right-inclined-wheel-equipped leaning vehicle having the fifth configuration, the left inclined wheel and the right inclined wheel are front wheels, and the other inclined wheel is a rear wheel. In this case, the leaning posture control device can make a braking torque of one of the left inclined wheel and the right inclined wheel at an outer side of turning larger than a braking torque of one of the left inclined wheel and the right inclined wheel at an inner side of turning in a case where the lean body frame is leaned in the left direction or in the right direction and side-slip occurs in the other inclined wheel while the vehicle is turning. The leaning posture control device can also make the braking torque of the one of the left inclined wheel and the right inclined wheel at the outer side of turning smaller than the braking torque of the one of the left inclined wheel and the right inclined wheel at the inner side of turning in a case where the lean body frame is leaned in the left direction or in the right direction and side-slip occurs in the left inclined wheel and the right inclined wheel while the vehicle is turning. 
     In a case where the left inclined wheel and the right inclined wheel are front wheels and the other inclined wheel is a rear wheel, the leaning posture control device may have the following configuration. In a case where the other inclined wheel slips sideways while the vehicle is turning with the lean body frame leaned in the left direction or in the right direction, the leaning posture control device can make a driving torque of one of the left inclined wheel and the right inclined wheel at the outer side in turning smaller than a driving torque of the wheel at the inner side of turning. In addition, in a case where the left inclined wheel and the right inclined wheel slip sideways while the vehicle is turning with the lean body frame leaned in the left direction or in the right direction, the leaning posture control device can make a driving torque of one of the left inclined wheel and the right inclined wheel at the outer side of turning larger than a driving torque of the wheel at the inner side of turning. 
     (Sixth Configuration) 
     A sixth configuration is a configuration of the left-right-inclined-wheel-equipped leaning vehicle including the leaning posture control device having one of the first through fourth configurations. In the left-right-inclined-wheel-equipped leaning vehicle having the sixth configuration, the left inclined wheel and the right inclined wheel are rear wheels, and the other inclined wheel is a front wheel. In this case, the leaning posture control device can make a braking torque of one of the left inclined wheel and the right inclined wheel at an outer side of turning smaller than a braking torque of one of the left inclined wheel and the right inclined wheel at an inner side of turning in a case where the lean body frame is leaned in the left direction or in the right direction and side-slip occurs in the other inclined wheel while the vehicle is turning. In addition, the leaning posture control device can also make the braking torque of the one of the left inclined wheel and the right inclined wheel at the outer side of turning larger than the braking torque of the one of the left inclined wheel and the right inclined wheel at the inner side of turning in a case where the lean body frame is leaned in the left direction or in the right direction and side-slip occurs in the left inclined wheel and the right inclined wheel while the vehicle is turning. 
     In a case where the left inclined wheel and the right inclined wheel are rear wheels and the other inclined wheel is a front wheel, the leaning posture control device may take the following configuration. In a case where the other inclined wheel slips sideways while the vehicle is turning with the lean body frame leaned in the left direction or in the right direction, the leaning posture control device can make a driving torque of one of the left inclined wheel and the right inclined wheel at the outer side of turning larger than a driving torque of the wheel at the inner side of turning. In addition, in a case where the left inclined wheel and the right inclined wheel slip sideways while the vehicle is turning with the lean body frame leaned in the left direction or in the right direction, the leaning posture control device can make a driving torque of one of the left inclined wheel and the right inclined wheel at the outer side of turning smaller than a driving torque of the wheel at the inner side of turning. 
     Advantageous Effects of Invention 
     According to the present teaching, a leaning posture of a left-right-inclined-wheel-equipped leaning vehicle can be controlled by a means different from a lean actuator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a straddled vehicle. 
         FIG. 2  is a front view of the straddled vehicle when a body frame is in an upright position. 
         FIG. 3  is an enlarged view of a portion of  FIG. 2 . 
         FIG. 4  is a plan view illustrating a configuration of the vehicle illustrated in  FIG. 2  when viewed from above. 
         FIG. 5  is a view illustrating a vehicle front portion in a state where front wheels are steered. 
         FIG. 6  is a front view of the vehicle in a state where the body frame is leaned. 
         FIG. 7  is a front view of the vehicle in a state where the front wheels are steered and the body frame is leaned. 
         FIG. 8  is a functional block diagram illustrating a lean detecting section. 
         FIG. 9A  is a schematic illustration of an acceleration generated at a barycenter of the vehicle. 
         FIG. 9B  is a schematic illustration of an angular velocity generated in the vehicle. 
         FIG. 10  is a side view of a left buffer of the vehicle illustrated in  FIG. 1 . 
         FIG. 11  is a block diagram illustrating a brake system included in the vehicle. 
         FIG. 12  is a functional block diagram of a configuration according to a first embodiment. 
         FIG. 13  is a control flowchart of reducing a yaw moment deviation amount. 
         FIG. 14  is a graph showing a relationship among a slip ratio, a braking force, and a lateral force. 
         FIG. 15  shows illustrations for describing an example of motion of a vehicle in an embodiment. 
         FIG. 16  shows illustrations for describing an example of motion of the vehicle in the embodiment. 
         FIG. 17  shows illustrations for describing an example of motion of the vehicle in the embodiment. 
         FIG. 18  is an illustration for describing values in calculating a target yaw moment deviation amount. 
     
    
    
     DETAILED DESCRIPTION 
     In this specification, a “yaw angle” refers to a rotation angle of a body frame around an axis in the top-bottom direction (vertical direction) of a vehicle. A “yaw angular velocity” refers to a rate of change in the “yaw angle.” A “roll angle” refers to a rotation angle of the body frame around an axis in the front-rear direction (longitudinal direction) of the vehicle. A “roll angular velocity” refers to a rate of change in the “roll angle.” A lean angle of the body frame in the left direction of the vehicle or in the right direction of the vehicle can be expressed using the roll angle. A “pitch angle” refers to a rotation angle of the body frame around the axis in the left-right direction of the vehicle. A “pitch angular velocity” refers to a rate of change in the “pitch angle.” 
     First, with reference to  FIG. 15 , a left-right-inclined-wheel-equipped leaning vehicle according to an embodiment of the present teaching will be briefly described. The left-right-wheel-equipped leaning vehicle includes a lean body frame  15 , and also includes a left inclined wheel  3   a , a right inclined wheel  3   b , and another inclined wheel  5  supported on the lean body frame  15 . The lean body frame  15  leans leftward when the left-right-wheel-equipped leaning vehicle turns leftward in the left-right direction of the vehicle, and leans rightward when the left-right-wheel-equipped leaning vehicle turns rightward in the left-right direction of the vehicle. The left inclined wheel  3   a  and the right inclined wheel  3   b  are arranged in the left-right direction of the vehicle. The other inclined wheel  5  is disposed ahead of or behind the left inclined wheel  3   a  and the right inclined wheel  3   b  in the front-rear direction of the vehicle. The left inclined wheel  3   a , the right inclined wheel  3   b , and the other inclined wheel  5  lean leftward when the left-right-wheel-equipped leaning vehicle turns leftward in the left-right direction of the vehicle, and lean rightward when the left-right-wheel-equipped leaning vehicle turns rightward in the left-right direction of the vehicle. 
     The left-right-inclined-wheel-equipped leaning vehicle includes a leaning posture control device  200  for controlling a leaning posture of the left-right-inclined-wheel-equipped leaning vehicle. The leaning posture control device  200  controls a torque of at least one of the left inclined wheel  3   a  or the right inclined wheel  3   b  arranged in the left-right direction of the vehicle so as to suppress a change in a lean of the lean body frame  15  in the left direction while the lean body frame  15  is leaned in the left direction or a change in a lean of the lean body frame  15  in the right direction while the lean body frame  15  is leaned in the right direction, based on physical quantities concerning side-slip of the left inclined wheel  3   a , the right inclined wheel  3   b , and the other inclined wheel  5  disposed ahead of or behind the left inclined wheel  3   a  and the right inclined wheel  3   b.    
     For example, as illustrated in  FIG. 15 , in a case where the left inclined wheel  3   a  and the right inclined wheel  3   b  slip sideways while the vehicle is turning with the lean body frame  15  leaned in the left direction or in the right direction, the leaning posture control device  200  makes a braking torque of one of the left inclined wheel  3   a  and the right inclined wheel  3   b  at the outer side of turning smaller than a braking torque of the wheel at the inner side of turning. Alternatively, in this case, the leaning posture control device  200  may make the driving torque of the one of the left inclined wheel  3   a  and the right inclined wheel  3   b  at the outer side of turning larger than the driving torque of the wheel at the inner side of turning. 
     In the example illustrated in  FIG. 15 , the side-slip of the left inclined wheel  3   a  and the right inclined wheel  3   b  increases the radius of turning so that a centrifugal force decreases. Accordingly, a force of leaning the lean body frame  15  to the inner side of turning, that is, rightward, is generated. On the other hand, the leaning posture control device  200  makes longitudinal forces of the left inclined wheel  3   a  and the right inclined wheel  3   b  different from each other so that a force of leaning the lean body frame  15  to the outer side of turning, that is, leftward, is generated. Consequently, a change in a lean of the lean body frame  15  in the left direction or in the right direction is suppressed. 
     Alternatively, as illustrated in  FIG. 16 , in a case where the other inclined wheel  5  slips sideways while the vehicle is turning with the lean body frame  15  leaned in the left direction or in the right direction, the leaning posture control device  200  makes the braking torque of the one of the left inclined wheel  3   a  and the right inclined wheel  3   b  at the outer side of turning larger than the braking torque of the wheel at the inner side of turning. Alternatively, in this case, the leaning posture control device  200  may make the driving torque of the one of the left inclined wheel  3   a  and the right inclined wheel  3   b  at the outer side of turning smaller than the driving torque of the wheel at the inner side of turning. 
     In the example illustrated in  FIG. 16 , the side-slip of the other inclined wheel  5  reduces the radius of turning so that a centrifugal force increases. Accordingly, a force of leaning the lean body frame  15  to the outer side of turning, that is, leftward, is generated. On the other hand, the leaning posture control device  200  makes longitudinal forces of the left inclined wheel  3   a  and the right inclined wheel  3   b  different from each other so that a force of leaning the lean body frame  15  to the inner side of turning, that is, rightward, is generated. Consequently, a change in a lean of the lean body frame  15  in the left direction or in the right direction is suppressed. 
     An embodiment of the present teaching will be further described. In the following description, the left-right-inclined-wheel-equipped leaning vehicle will be referred to as a vehicle or a leaning vehicle. The leaning posture control device will be referred to as a posture control device. The lean body frame will be referred to as a body frame. 
     (First Configuration) 
     A posture control device with a first configuration of an embodiment of the present teaching is 
     a posture control device for controlling a posture of a straddled vehicle that turns with a lean, the straddled vehicle including a front wheel and a rear wheel one of which includes left and right wheels, and the posture control device includes: 
     a target yaw moment deviation amount calculating section that calculates a target yaw moment deviation amount based on a side-slip acceleration of each wheel, a length from the vehicle center to a front wheel shaft, a length from the vehicle center to a rear wheel shaft, and a load on each wheel; 
     a determination section that determines whether the target yaw moment deviation amount calculated by the target yaw moment deviation amount calculating section is less than or equal to a threshold or not; and 
     a torque control section that controls a torque in each wheel based on a longitudinal force of each wheel and a lateral force of each wheel in such a manner that the target yaw moment deviation amount is less than or equal to the threshold, if the determination section determines that the target yaw moment deviation amount is not less than or equal to the threshold. 
     In a case where the front wheels include left and right wheels, “each wheel” in the first configuration refers to the front left wheel, the front right wheel, and a rear wheel. In this case, the front left wheel is an example of a left inclined wheel, the front right wheel is an example of a right inclined wheel, and the rear wheel is an example of another inclined wheel. In a case where the rear wheel includes left and right wheels, “each wheel” refers to the front wheel, the rear left wheel, and the rear right wheel. In this case, the rear left wheel is an example of the left inclined wheel, the rear right wheel is an example of the right inclined wheel, and the front wheel is an example of the other inclined wheel. The torque control section controls at least one of a braking force or a driving force of each wheel, as a torque of each wheel. 
     In the first configuration, the “longitudinal force” may be calculated by conversion from a brake fluid pressure. The “lateral force” may be calculated by conversion from a vehicle body roll angle (θ). During anti-lock control, a longitudinal force may be calculated by conversion from a brake fluid pressure when a slip ratio is changed, and the slip ratio. During anti-lock control, a lateral force may be calculated by conversion from a vehicle body roll angle and a slip ratio. 
     (Second Configuration) 
     In the first configuration, the posture control device may include: 
     a longitudinal force calculating section and a lateral force calculating section that calculate a longitudinal force estimated value in each wheel and a lateral force estimated value in each wheel, respectively, in a case where a braking force or a driving force in each wheel is changed if the determination section determines that the target yaw moment deviation amount is not less than or equal to the threshold; 
     a yaw moment change rate calculating section that calculates a yaw moment change rate around a vehicle center axis, based on the longitudinal force estimated value in each wheel and the lateral force estimated value in each wheel respectively calculated by the longitudinal force calculating section and the lateral force calculating section, a wheel base, and a tread width; 
     a deviation determination section that determines whether each of the target yaw moment deviation amount calculated by the target yaw moment deviation amount calculating section and the yaw moment change rate calculated by the yaw moment change rate calculating section is less than or equal to a predetermined value or not; and 
     a torque calculating section that calculates a torque (a braking force or a driving force) of each wheel that can obtain the yaw moment change rate if the deviation determination section determines that the deviation is less than or equal to the predetermined value. In this case, the torque control section may control a torque of each wheel based on the torque of each wheel calculated by the torque calculating section (second configuration). The longitudinal force calculating section and the lateral force calculating section can use, for example, a brake fluid pressure as a braking force in each wheel. As the torque in each wheel, the torque control section can use at least one of a driving force or a braking force, for example. 
     The foregoing configuration can control a driving force and/or a braking force of each wheel in such a manner that a yaw moment deviation amount is less than or equal to a predetermined value. For example, torque control is performed on each wheel by using geometrical arrangement of the front left and right wheels and the rear wheel (or the front wheel and the rear left and right wheels) so that the posture of the vehicle can be controlled. For example, a posture of a vehicle whose front left and right wheels are traveling on road surfaces having different friction coefficients (including straight-ahead traveling and curve traveling) can be controlled. In addition, a posture of the vehicle that is turning with a lean during actuation of an ABS (in a state with a small lateral force) can be controlled. 
     (Third Configuration) 
     In the second configuration, 
     if the deviation determination section determines that the deviation is not less than or equal to the predetermined value, processes of the longitudinal force calculating section, the lateral force calculating section, the yaw moment change rate calculating section, and the deviation determination section may be repeated. Accordingly, an optimum solution search loop may be executed (Third Configuration). 
     (Fourth Configuration) 
     In the second or third configuration, 
     the longitudinal force calculating section may calculate the longitudinal force estimated value by conversion from a changed brake fluid pressure or a changed engine torque. The lateral force calculating section may calculate the lateral force estimated value by conversion from a vehicle body roll angle (θ) (fourth configuration). 
     (Fifth Configuration) 
     In any one of the second through fourth configurations, 
     the longitudinal force calculating section may calculate the longitudinal force estimated value by conversion from a brake fluid pressure and a slip ratio in changing the slip ratio during anti-lock control. The lateral force calculating section may calculate the lateral force estimated value by conversion from a vehicle body roll angle and the slip ratio during anti-lock control. An anti-lock operation of each of the front wheel and the rear wheel may be corrected using the longitudinal force estimated value and the lateral force estimated value (Fifth Configuration). 
     (Sixth Configuration) 
     In any one of the first through fifth configurations, the posture control device may further include 
     a suppression section that suppresses a vehicle body roll behavior, that is, a tilt motion, occurring when the torque control section controls a torque in each wheel (sixth configuration). The suppression section may issue instructions to a tilt mechanism to suppress a tilt motion. 
     (Seventh Configuration) 
     In any one of the second through sixth configurations, 
     the torque calculating section may include a brake fluid pressure calculating section that calculates a brake fluid pressure in each wheel that can obtain the yaw moment change rate. The torque control section may include a brake fluid pressure control section that controls a brake fluid pressure in a fluid pressure controlling unit, based on the brake fluid pressure calculated by the brake fluid pressure calculating section (seventh configuration). 
     (Eighth Configuration) 
     In any one of the second through seventh configurations, 
     the torque calculating section may include a driving force calculating section that calculates a driving force in each wheel that can obtain the yaw moment change rate. The torque control section may include a driving force controlling section that controls a driving force based on the driving force calculated by the driving force calculating section. 
     The posture control device may further include: 
     a lean angle calculating section that calculates a lean angle (roll angle) of the vehicle based on a roll rate; 
     a vehicle speed detecting section that calculates a vehicle body speed of the vehicle in a traveling direction based on a longitudinal acceleration, a front wheel speed Vf, and a rear wheel speed Vr; and 
     a side-slip acceleration calculating section that calculates a front wheel side-slip acceleration and a rear wheel side-slip acceleration based on a yaw rate, a lean angle of the vehicle body, a lateral acceleration, and the vehicle body speed calculated by the vehicle speed detecting section. 
     A target yaw moment deviation amount may be obtained by the expression below. In the expression, the upper equation represents a case where a target yaw moment deviation amount is obtained using a static value, and the lower equation represents a case where a target yaw moment deviation amount is obtained using a dynamic value. 
     
       
         
           
             
               
                 
                   
                     
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                   [ 
                   
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     where r (=dΨ/dt) is a yaw rate on a tire ground plane, Vf is a side-slip speed (integral value of a side-slip acceleration) of a front wheel speed, and Vr is a side-slip speed of a rear wheel speed, and ΔI is a yaw moment of inertia (inertia). 
     As one embodiment of the present teaching, the longitudinal force calculating section may estimate a longitudinal force based on a detection value of a throttle sensor and a detection value (brake pressure) of a brake modulator. Suppose θ is a roll angle, θ″ is a roll angle acceleration, h is a distance between a barycenter point and an intersection point, Ay is a ground position lateral acceleration, and Ftotal is a lateral force, the lateral force calculating section may calculate a lateral force Ftotal using the following equation:
 
 F total= m·Ay+m·h ·θ″/cos θ
 
     The ground position lateral acceleration Ay is calculated based on a lateral acceleration, a roll angle acceleration, a yaw angle acceleration, a roll angle, and a barycenter point of the vehicle. 
     As one embodiment of the present teaching, the brake fluid pressure control section may perform control concerning opening and closing operations of a retention valve and a pressure reducing valve, and control concerning a driving stop operation of a pump. With this configuration, a brake fluid pressure in each wheel can be controlled so that a braking force of each wheel is changed and, thereby, a posture of the vehicle can be controlled. 
     As one embodiment of the present teaching, in a case where the torque control section controls a driving force of each wheel, a wheel-in motor is disposed in at least front wheels (the front right wheel and the front left wheel), and the torque control section may control the wheel-in motor. 
     As one embodiment of the present teaching, 
     the straddled vehicle further includes: 
     a roll rate sensor that detects a roll rate of the vehicle; 
     a yaw rate sensor that detects a yaw rate of the vehicle; 
     a lateral acceleration sensor that detects a lateral acceleration of the vehicle; 
     a longitudinal acceleration sensor that detects a longitudinal acceleration of the vehicle; 
     a front wheel speed sensor that detects a front wheel speed of the vehicle; and 
     a rear wheel speed sensor that detects a rear wheel speed of the vehicle. 
     In a case where the front wheels include left and right wheels, the straddled vehicle may include a front right wheel speed sensor that detects a front right wheel speed and a front left wheel speed sensor that detects a front left wheel speed. 
     As one embodiment of the present teaching, 
     the posture control device may further include a storage section that stores: 
     a roll rate detected by a roll rate sensor that detects a roll rate of the vehicle; 
     a yaw rate detected by a yaw rate sensor that detects a yaw rate of the vehicle; 
     a lateral acceleration detected by a lateral acceleration sensor that detects a lateral acceleration of the vehicle; 
     the longitudinal acceleration detected by the longitudinal acceleration sensor that detects a longitudinal acceleration of the vehicle; 
     a front wheel speed detected by a front wheel speed sensor that detects a front wheel speed of the vehicle; and 
     a rear wheel speed detected by a rear wheel speed sensor that detects a rear wheel speed of the vehicle. 
     In the case where the front wheels include left and right wheels, for example, the front wheel speed may be a front right wheel speed detected by the front right wheel speed sensor that detects a front right wheel speed and a front left wheel speed detected by the front left wheel speed sensor that detects a front left wheel speed. 
     As one embodiment of the present teaching, 
     the posture control device may further include a storage section that stores: 
     a roll rate of the vehicle; 
     a yaw rate of the vehicle; 
     a lateral acceleration of the vehicle; 
     a longitudinal acceleration of the vehicle; 
     a front wheel speed of the vehicle; and 
     a rear wheel speed of the vehicle. 
     In the case where the front wheels include left and right wheels, the front wheel speed may be, for example, a front right wheel speed and a front left wheel speed. 
     (Ninth Configuration) 
     A straddled vehicle with a ninth configuration is 
     a straddled vehicle including at least one front wheel and at least one rear wheel, one of which includes left and right wheels, wherein the straddled vehicle turns with a lean, and the posture control device with any one of the first through eighth configurations is mounted on the straddled vehicle. 
     The straddled vehicle with the ninth configuration includes a tilt mechanism section that may include a suppression mechanism that suppresses a tilt motion. 
     The straddled vehicle may further include: 
     a body frame; 
     a right front wheel and a left front wheel arranged in a left-right direction when the vehicle whose body frame is in an upright position is seen from the front; 
     a center rear wheel disposed behind the right front wheel and the left front wheel in a front-rear direction of the body frame and disposed between the right front wheel and the left front wheel when the vehicle whose body frame is in the upright position is seen from the front; 
     a right buffer device that supports the right front wheel on a lower portion of the right buffer device and buffers displacement of the right front wheel relative to an upper portion of the right buffer device in a top-bottom direction of the body frame; 
     a left buffer device that supports the left front wheel on a lower portion of the left buffer device and buffers displacement of the left front wheel relative to an upper portion of the left buffer device in a top-bottom direction of the body frame; and 
     a linkage mechanism that is disposed above the right front wheel and the left front wheel in a top-bottom direction of the body frame in the upright position, and that rotatably supports an upper portion of the right buffer device and an upper portion of the left buffer device, at least a portion of the linkage mechanism being supported by the body frame to be rotatable about a rotation axis extending forward in the front-rear direction of the body frame and upward in the top-bottom direction of the body frame. 
     Another teaching provides a straddled vehicle including at least one front wheel and at least one rear wheel one of which includes left and right wheels, and configured to turn with a lean, wherein the posture control device described above is mounted on the straddled vehicle. 
     In the teaching, the tilt mechanism section of the vehicle includes a suppression mechanism that suppresses a tilt motion. Examples of the suppression mechanism include a damper that can be electronically controlled, wherein the damper can suppress a tilt motion by reducing a rotational speed of the linkage mechanism. The tilt motion is suppressed in accordance with instructions from the suppression section of the posture control device. 
     With this configuration, braking and driving forces of each wheel for controlling a posture of the vehicle are incorporated with a tilt motion so that the change rate of a vehicle behavior with changes in braking and driving forces can be reduced, and in addition, the effect of suppressing a vehicle behavior can be enhanced. 
     Embodiments of the present teaching will be described hereinafter with reference to the drawings. 
     In the drawings, arrow F represents the forward direction of the vehicle. Arrow B represents the rearward direction of the vehicle. Arrow U represents the upward direction of the vehicle. Arrow D represents the downward direction of the vehicle. Arrow R represents the rightward direction of the vehicle. Arrow L represents the leftward direction of the vehicle. 
     The vehicle turns with a body frame being leaned in the left direction of the vehicle or in the right direction of the vehicle relative to the vertical direction. Thus, in addition to the directions relative to the vehicle, directions relative to the body frame are defined. In the accompanying drawings, arrow FF represents the forward direction of the body frame. Arrow FB represents the rearward direction of the body frame. Arrow FU represents the upward direction of the body frame. Arrow FD represents the downward direction of the body frame. Arrow FR represents the rightward direction of the body frame. Arrow FL represents the leftward direction of the body frame. 
     The “top-bottom direction of the body frame” herein refers to the top-bottom direction relative to the body frame when seen from a rider driving the vehicle. The “left-right direction of the body frame” herein refers to the left-right direction relative to the body frame when seen from the rider driving the vehicle. The “front-rear direction of the body frame” herein refers to the front-rear direction relative to the body frame when seen from the rider driving the vehicle. 
     In a left-right-wheel-equipped leaning vehicle to which this embodiment is applied, when the top-bottom direction of the body frame coincides with the vertical direction, the body frame is in an upright position. At this time, the top-bottom direction, the left-right direction, and the front-rear direction of the vehicle respectively coincide with the top-bottom direction, the left-right direction, and the front-rear direction of the body frame. The vertical direction is the same as a gravity direction. 
     When the left-right-wheel-equipped leaning vehicle to which this embodiment is applied travels with the body frame leaned in the left direction of the vehicle or in the right direction of the vehicle relative to the vertical direction during turning. At this time, the top-bottom direction of the vehicle does not coincide with the top-bottom direction of the body frame. Even when the body frame leans in the left direction or in the right direction relative to the vertical direction, the front-rear direction of the vehicle coincides with the front-rear direction of the body frame. 
     &lt;Vehicle Body Structure&gt; 
       FIG. 1  is a schematic side view of a straddled vehicle according to this embodiment when seen from the left in the left-right direction of a body frame. It is assumed that in a vehicle  1  illustrated in  FIG. 1 , front wheels are steering wheels and a rear wheel is a non-steering wheel. The straddled vehicle according to this embodiment is an example of a left-right-wheel-equipped leaning vehicle. 
     As illustrated in  FIG. 1 , the vehicle  1  includes, for example, a pair of left and right front wheels  3  ( 3   a  and  3   b ), a rear wheel  5 , a steering mechanism  7 , a linkage mechanism  9 , a power unit  11 , a seat  13 , and a body frame  15 , for example. For convenience of illustration,  FIG. 1  illustrates only the left front wheel  3   a  and does not illustrate the right front wheel  3   b . In  FIG. 1 , a portion of the body frame  15  hidden by the vehicle body is indicated by broken lines. 
     The body frame  15  includes a head pipe  21 , a down frame  22 , an under frame  23 , and a rear frame  24 . The body frame  15  supports, for example, the power unit  11  and the seat  13 . 
     The power unit  11  includes a driving source such as an engine or an electric motor and a transmission device, for example. The power unit  11  supports the rear wheel  5 . A driving force of the driving source is transferred to the rear wheel  5  through the transmission device. The power unit  11  is swingably supported by the body frame  15 , and the rear wheel  5  is configured to be displaced upward or downward of the body frame  15 . 
     The head pipe  21  is disposed in a front portion of the vehicle  1 , and rotatably supports a steering shaft  31  of the steering mechanism  7  (see  FIG. 2  described later). The head pipe  21  is disposed in such a manner that an upper portion of the head pipe  21  is located behind a lower portion of the head pipe  21  when the body frame  15  is seen in the left-right direction of the vehicle  1 . A rotation axis of the head pipe  21  is inclined relative to the top-bottom direction of the body frame  15  and extends upward and rearward of the body frame  15 . 
     The steering mechanism  7  and the linkage mechanism  9  are disposed around the head pipe  21 . The head pipe  21  supports the linkage mechanism  9 , and more specifically, rotatably supports at least a portion of the linkage mechanism  9 . 
     The down frame  22  is connected to the head pipe  21 . The down frame  22  is disposed behind the head pipe  21 , and extends along the top-bottom direction of the vehicle  1 . The under frame  23  is connected to a lower portion of the down frame  22 . 
     The under frame  23  extends rearward from the lower portion of the down frame  22 . At the rear of the under frame  23 , the rear frame  24  extends rearward and upward. The rear frame  24  supports, for example, the seat  13 , the power unit  11 , and a tail lamp. 
     The body frame  15  is covered with a body cover  17 . The body cover  17  includes a front cover  26 , a pair of left and right front fenders  27  ( 27   a  and  27   b ), a leg shield  28 , a center cover  29 , and a rear fender  30 . The body cover  17  covers at least a portion of body parts mounted on the vehicle  1 , such as the pair of left and right front wheels  3 , the body frame  15 , and the linkage mechanism  9 . 
     The front cover  26  is located ahead of the seat  13 , and covers at least portions of the steering mechanism  7  and the linkage mechanism  9 . The leg shield  28  is configured to cover at least a portion of the legs of a rider from the front, and is disposed behind the pair of left and right front wheels  3  and ahead of the seat  13 . The center cover  29  is disposed to cover at least a portion of the periphery of the rear frame  24 . 
     At least a portion of the front fenders  27  is disposed below the front cover  26  and above the front wheels  3 . At least a portion of the rear fender  30  is disposed above the rear wheel  5 . 
     In the upright position of the vehicle  1 , at least portions of the front wheels  3  ( 3   a  and  3   b ) are disposed below the head pipe  21  and below the front cover  26 . At least a portion of the rear wheel  5  is disposed below the center cover  29  or the seat  13  and below the rear fender  30 . 
     The front wheels  3  are provided with front wheel vehicle speed sensors  41 , and the rear wheel  5  is provided with a rear wheel vehicle speed sensor  42 . Based on a detection result obtained by these sensors ( 41  and  42 ), a vehicle speed of the vehicle  1  is estimated by computation. The vehicle  1  includes, at an arbitrary position, a lean detecting section  50  that detects a lean state of the vehicle  1 , and detects a lean state of the vehicle  1  based on the estimated vehicle speed and other parameters. The lean detecting section  50  is constituted by a predetermined sensor group and a computation device. This will be described in detail later. 
     In addition, the vehicle  1  includes, inside the vehicle  1 , a torque control section  100  that controls a braking torque transferred from the front wheels  3  ( 3   a  and  3   b ) corresponding to the steering wheels to the road surface. The torque control section  100  is constituted by, for example, an electronic control unit, and is disposed under the seat  13 , for example. 
     &lt;Steering Mechanism&gt; 
       FIG. 2  is a front view of a front portion of the vehicle  1  in which the body frame  15  is in the upright position, seen from the front.  FIG. 3  is an enlarged view of a portion of  FIG. 2 .  FIG. 4  is a plan view of the vehicle  1  illustrated in  FIG. 2  when seen from above. For convenience of the drawings,  FIGS. 2 and 4  do not show the body cover  17 . 
     As illustrated in  FIGS. 2 and 4 , the steering mechanism  7  includes a steering force transfer mechanism  71  and buffers  73  ( 73   a  and  73   b ). 
     The left front wheel  3   a  is disposed at the left of the down frame  22 , and is supported by the left buffer  73   a . The left front fender  27   a  is disposed above the left front wheel  3   a . Similarly, the right front wheel  3   b  is disposed at the right of the down frame  22 , and is supported by the right buffer  73   b . The right front fender  27   b  is disposed above the right front wheel  3   b.    
     The buffers  73  ( 73   a  and  73   b ) are so-called telescopic buffers. The left buffer  73   a  is provided in order to attenuate vibrations caused by a load on the left front wheel  3   a  supported by the left buffer  73   a  from the road surface. Similarly, the right buffer  73   b  is provided in order to attenuate vibrations caused by a load on the right front wheel  3   b  supported by the right buffer  73   b  from the road surface. 
     When the vehicle  1  is seen from the front with the body frame  15  being in the upright position, the steering force transfer mechanism  71  is disposed above the front wheels  3  ( 3   a  and  3   b ). The steering force transfer mechanism  71  includes a steering member for inputting a steering force of the rider. The steering member includes a steering shaft  31  and a handlebar  32  coupled to an upper portion of the steering shaft  31 . A portion of the steering shaft  31  is rotatably supported by the head pipe  21 , and rotates in cooperation with an operation of the handlebar  32  by the rider. The rotation axis of the steering shaft  31  extends rearward and upward of the body frame  15 . 
     The steering force transfer mechanism  71  includes steering members including the steering shaft  31  and the handlebar  32 , a tie rod  33 , and brackets  34  ( 34   a  and  34   b ). The steering force transfer mechanism  71  transfers a steering force with which the rider operates the handlebar  32 , to the brackets  34  ( 34   a  and  34   b ). 
     &lt;Linkage Mechanism&gt; 
     The vehicle  1  according to this embodiment includes the linkage mechanism  9  of a parallel four-bar linkage (also called parallelogram linkage) type. 
     The linkage mechanism  9  is disposed below the handlebar  32  when the vehicle  1  with the body frame  15  being in the upright position is seen from the front, and is supported by the head pipe  21 . The linkage mechanism  9  includes cross members  35  ( 35   a ,  35   b ,  35   c , and  35   d ). 
     The upper cross member  35   a  is disposed ahead of the head pipe  21  and extends in the vehicle width direction. An intermediate portion of the upper cross member  35   a  is supported on the head pipe  21  by a support part  36   a . The support part  36   a  is a boss part provided on the head pipe  21 . The upper cross member  35   a  is rotatable about an intermediate upper axis extending in the front-rear direction of the body frame  15 , with respect to the head pipe  21 . 
     The left end of the upper cross member  35   a  is supported on the left cross member  35   b  by a support part  36   b . The support part  36   b  is a boss part provided on the left cross member  35   b . The right end of the upper cross member  35   a  is supported on the right cross member  35   c  by a support part  36   c . The support part  36   c  is a boss part provided on the right cross member  35   c.    
     The upper cross member  35   a  is rotatable about a left upper axis extending in the front-rear direction of the body frame  15 , with respect to the left cross member  35   b . The upper cross member  35   a  is rotatable about a right upper axis extending in the front-rear direction of the body frame  15 , with respect to the right cross member  35   c . The intermediate upper axis, the left upper axis, and the right upper axis are substantially parallel. The intermediate upper axis, the left upper axis, and the right upper axis extend forward in the front-rear direction of the body frame  15  and upward in the top-bottom direction of the body frame  15 . 
     An intermediate portion of the lower cross member  35   d  is supported on the head pipe  21  by a support part  36   d . The support part  36   d  is a boss part provided on the head pipe  21 . The lower cross member  35   d  is rotatable about an intermediate lower axis extending in the front-rear direction of the body frame  15 , with respect to the head pipe  21 . When the vehicle with the body frame  15  in the upright position is seen from the front, the lower cross member  35   d  is disposed below the upper cross member  35   a  in the top-bottom direction of the body frame  15 . The lower cross member  35   d  has substantially the same length in the vehicle width direction as that of the upper cross member  35   a , and is disposed substantially in parallel with the upper cross member  35   a.    
     The left end of the lower cross member  35   d  is supported on the left cross member  35   b  by a support part  36   e . The support part  36   e  is a boss part provided on the left cross member  35   b . The right end of the lower cross member  35   d  is supported on the right cross member  35   c  by a support part  36   f  The support part  36   f  is a boss part provided on the right cross member  35   c . The lower cross member  35   d  is rotatable about a left lower axis extending in the front-rear direction of the body frame  15 , with respect to the left cross member  35   b . Similarly, the lower cross member  35   d  is rotatable about a right lower axis extending in the front-rear direction of the body frame  15 , with respect to the right cross member  35   c . The intermediate lower axis, the left lower axis, and the right lower axis are substantially parallel. The intermediate lower axis, the left lower axis, and the right lower axis extend forward and upward of the body frame  15 . 
     At least a portion of the linkage mechanism  9  is rotatable about an intermediate axis extending in the front-rear direction of the vehicle  1 . At least a portion of the linkage mechanism  9  is rotatable about an intermediate axis (rotation axis) extending forward and upward of the body frame  15 . The intermediate axis (rotation axis) inclines relative to the horizontal direction, and extends forward and upward relative to the horizontal direction. 
     The left cross member  35   b  is disposed at the left of the head pipe  21 . The left cross member  35   b  is disposed above the left front wheel  3   a  and the left buffer  73   a . The left buffer  73   a  is disposed to be rotatable about a left center axis Y 1  with respect to the left cross member  35   b . The left center axis Y 1  is substantially in parallel with the rotation axis of the head pipe  21 . 
     The right cross member  35   c  is located at the right of the head pipe  21 . The right cross member  35   c  is disposed above the right front wheel  3   b  and the right buffer  73   b . The right buffer  73   b  is disposed to be rotatable about a right center axis Y 2  with respect to the right cross member  35   c . The right center axis Y 2  is substantially in parallel with the rotation axis of the head pipe  21 . 
     In this manner, the cross members  35  ( 35   a ,  35   b ,  35   c , and  35   d ) are supported in such a manner that the upper cross member  35   a  and the lower cross member  35   d  are kept substantially in parallel with each other and the left cross member  35   b  and the right cross member  35   c  are kept substantially in parallel with each other. 
     &lt;Steering Operation&gt; 
       FIG. 5  is a view for describing a steering operation of the vehicle  1 .  FIG. 5  illustrates a configuration of the vehicle  1  in a steered state when seen from the front.  FIG. 5  corresponds to a view of the vehicle  1  in which the body frame  15  is in the upright position and the pair of left and right front wheels  3  are steered is seen from above the body frame  15 . 
     As illustrated in  FIG. 5 , when the handlebar  32  is turned, the steering mechanism  7  operates, and a steering operation is performed. 
     For example, when the steering shaft  31  rotates in the direction indicated by arrow T 1  in  FIG. 5 , for example, the tie rod  33  moves left-rearward. With the left-rearward movement of the tie rod  33 , the brackets  34  ( 34   a  and  34   b ) rotate in the direction indicated by arrow T 1 . With this rotation, the left front wheel  3   a  rotates about the left center axis Y 1  (see  FIGS. 2 and 3 ), and the right front wheel  3   b  rotates about the right center axis Y 2  (see  FIGS. 2 and 3 ). 
     &lt;Lean Motion&gt; 
       FIG. 6  is a view for describing a lean motion of the vehicle  1 .  FIG. 6  corresponds to a view in which the vehicle  1  whose body frame  15  is leaned to the left of the vehicle  1  is seen from the front of the vehicle  1 . 
     The linkage mechanism  9  forms substantially a rectangle when the vehicle  1  whose body frame  15  is in the upright position is seen from the front, and forms a substantially parallelogram when the vehicle  1  whose body frame  15  is leaned in the left direction of the vehicle  1  is seen from the front. Deformation of the linkage mechanism  9  is in conjunction with a lean of the body frame  15  in the left direction or in the right direction. An operation of the linkage mechanism  9  refers to a change of the shape of the linkage mechanism  9  caused when the cross members  35  ( 35   a ,  35   b ,  35   c , and  35   d ) of the linkage mechanism  9  for performing a lean motion rotate relative to each other using their support points as axes. 
     For example, the cross members  35  ( 35   a ,  35   b ,  35   c , and  35   d ), which are arranged substantially in a rectangle in a front view in the case where the vehicle  1  is in the upright position, is deformed into substantially a parallelogram in a state where the vehicle  1  leans. In conjunction with a lean of the body frame  15 , the left front wheel  3   a  and the right front wheel  3   b  also lean in the left direction of the vehicle  1  or in the right direction of the vehicle  1 . 
     For example, when the rider leans the vehicle  1  to the left, the head pipe  21  leans to the left relative to the vertical direction. When the head pipe  21  leans, the upper cross member  35   a  rotates about the support part  36   a  with respect to the head pipe  21 , and the lower cross member  35   d  rotates about the support part  36   d  with respect to the head pipe  21 . Then, the upper cross member  35   a  moves to the left of the lower cross member  35   d , and the left cross member  35   b  and the right cross member  35   c  lean relative to the vertical direction while being kept substantially in parallel with the head pipe  21 . At this time, the left cross member  35   b  and the right cross member  35   c  rotate with respect to the upper cross member  35   a  and the lower cross member  35   d . That is, when the vehicle  1  is leaned, the left cross member  35   b  and the right cross member  35   c  lean, and the left wheel  3   a  supported by the left cross member  35   b  and the right wheel  3   b  supported by the right cross member  35   c  lean relative to the vertical direction while being kept substantially in parallel with the head pipe  21 . 
     Even when the vehicle  1  leans, the tie rod  33  is kept substantially in parallel with the upper cross member  35   a  and the lower cross member  35   d.    
     In the manner described above, the linkage mechanism  9  that causes the left wheel  3   a  and the right wheel  3   b  to lean by performing the lean motion is disposed above the left wheel  3   a  and the right wheel  3   b . That is, the rotation axes of cross members  35  ( 35   a ,  35   b ,  35   c , and  35   d ) constituting the linkage mechanism  9  are disposed above the left wheel  3   a  and the right wheel  3   b.    
     &lt;Steering Operation+Lean Motion&gt; 
       FIG. 7  is a front view of the vehicle  1  in a state where the left wheel  3   a  and the right wheel  3   b  are steered and the body frame  15  is leaned in the left direction or in the right direction.  FIG. 7  illustrates a state where the left wheel  3   a  and the right wheel  3   b  are steered leftward to cause the body frame  15  to lean leftward.  FIG. 7  is a view of the vehicle  1  in which the pair of left and right front wheels  3  ( 3   a  and  3   b ) are steered with the body frame  15  leaned leftward in the vehicle  1 , seen from the front of the vehicle  1 . In an operation illustrated in  FIG. 7 , orientations of the front wheels  3  ( 3   a  and  3   b ) are changed by a steering operation, and the front wheels  3  ( 3   a  and  3   b ) lean together with the body frame  15  by the lean motion. In this state, the cross members  35  ( 35   a ,  35   b ,  35   c , and  35   d ) of the linkage mechanism  9  are formed in a parallelogram, and the tie rod  33  moves in a steering direction (leftward in  FIG. 7 ) and rearward. 
     &lt;Lean Detection&gt; 
       FIG. 8  is a functional block diagram illustrating a configuration of the lean detecting section  50 . In this embodiment, the lean detecting section  50  includes a vehicle speed detecting section  51 , a gyro sensor  53 , and a roll angle detecting section  54 . The vehicle speed detecting section  51  and the roll angle detecting section  54  can be implemented by, for example, an arithmetic processing device. The lean detecting section  50  is not limited to the configuration illustrated in  FIG. 8  as long as a lean state of the vehicle  1  can be detected. 
     When the rider steers the handlebar  32  of the vehicle  1  while turning around a curve (e.g., in the state illustrated in  FIG. 5 ), a yaw rate of the vehicle  1  changes. When the rider leans the vehicle  1  to the center of curve (e.g., in the state illustrated in  FIG. 6 ), a roll rate of the vehicle  1  changes. The gyro sensor  53  detects angular velocities in two axis directions of yaw and roll of the vehicle  1 . That is, the gyro sensor  53  detects the yaw rate and the roll rate of the vehicle  1 . 
     The front wheel vehicle speed sensors  41  detect a rotation speed of the front wheels  3 . The rear wheel vehicle speed sensor  42  detects a rotation speed of the rear wheel  5 . The vehicle  1  according to this embodiment includes the pair of front wheels  3  ( 3   a  and  3   b ). 
     The vehicle speed detecting section  51  detects the vehicle speed of the vehicle  1  based on detection values input from the front wheel vehicle speed sensor  41  and the rear wheel vehicle speed sensor  42 . The roll angle detecting section  54  receives a roll rate of the vehicle  1  from the gyro sensor  53 . Based on these input values, the roll angle detecting section  54  detects a roll angle (lean state) of the vehicle  1 . An example of a method for detecting a roll angle of the vehicle  1  will be described with reference to  FIGS. 9A and 9B . 
       FIG. 9A  schematically illustrates an acceleration generated at a barycenter  10  of the vehicle  1 .  FIG. 9B  schematically illustrates an angular velocity generated in the vehicle  1 , and shows that a vehicle body fixed axis (axis Y 1 ) passes through the barycenter  10  for convenience of description. Such a method for detecting a roll angle of the vehicle  1  is a detection method in an ideal state where the vehicle  1  is turning at a speed V in a lean-with state with a pitching and a tire thickness of the vehicle  1  ignored. The lean-with state refers to a state in which the vehicle body fixed axis (axis Y 1 ) and the upper body of the rider are on the same line. 
     With reference to  FIG. 9A , a relationship between a roll angle θ while the vehicle  1  is turning and the vehicle body speed V, a differentiation of a Euler&#39;s yaw angle  4 ′, and a gravitational acceleration g is expressed as follows: where (dΨ/dt) is a yaw rate (yaw angular velocity) as a time differential of a yaw angle.
 
θ=arctan( V ·( dΨ/dt )/ g )  (1)
 
     With reference to  FIG. 9B , a relationship between a roll angle θ while the vehicle  1  is turning and a yaw rate ω detected by the gyro sensor  53  fixed to the vehicle  1 , and a differentiation of a Euler&#39;s yaw angle Ψ is expressed as follows: where in  FIG. 9B , ω represents an angular velocity generated around the axis in the top-bottom direction fixed to the vehicle body, and the length of the arrow represents the degree of the angular velocity, and (dΨ/dt) is an angular velocity generated around the vertical axis.
 
θ=arccos(ω/( dΨ/dt ))  (2)
 
     From Equations (1) and (2), the following relationship is derived.
 
θ=arcsin( V·ω/g )  (3)
 
     &lt;Braking Operation&gt; 
       FIG. 10  is a side view illustrating an example configuration of the left buffer  73   a  when seen from the right side of the vehicle  1  illustrated in  FIG. 1 . The same holds for the right buffer, and thus, description will not be repeated. 
     As illustrated in  FIG. 10 , the left buffer  73   a  includes a left rear telescopic element  80   a , a left front telescopic element  81   a , a left cross member support part  82   a , and the left bracket  34   a . The left rear telescopic element  80   a  has an extension and contraction configuration that extends and contracts along the left center axis Y 1  under the presence of an elastic member (not shown) such as a spring and a buffer member (not shown) such as oil disposed therein. The left rear telescopic element  80   a  has a damper function of absorbing vibrations and shocks caused by a load exerted on the left front wheel  3   a  from the road surface. 
     The left front telescopic element  81   a  is disposed at the same side as the left rear telescopic element  80   a  with respect to the left front wheel  3   a  in the rotation axis of the left wheel shaft  83   a . The left rear telescopic element  80   a  and the left front telescopic element  81   a  are arranged in the front-rear direction of the vehicle at the right of the left front wheel  3   a  in the state where the vehicle  1  is in the upright position. The left front telescopic element  81   a  is disposed ahead of the left rear telescopic element  80   a . In a manner similar to the left rear telescopic element  80   a , the left front telescopic element  81   a  has an extension and contraction structure that extends and contracts along the left center axis Y 1 . The extension and contraction direction of the left rear telescopic element  80   a  and the extension and contraction direction of the left front telescopic element  81   a  are parallel when seen in the rotation axis direction of the left front wheel  3   a.    
     An upper portion of the left rear telescopic element  80   a  and an upper portion of the left front telescopic element  81   a  are coupled to each other by the left bracket  34   a . The lower end of the left front telescopic element  81   a  is coupled and fixed to a portion near the lower end of the left rear telescopic element  80   a . The left front wheel  3   a  is supported on the left bracket  34   a  by the two telescopic elements of the left rear telescopic element  80   a  and the left front telescopic element  81   a  arranged in parallel in the front-rear direction of the vehicle  1 . Thus, an outer element  84   a  located on a side of a lower portion of the left buffer  73   a  does not rotate about an axis parallel to the extension and contraction direction of the telescopic elements, relative to an inner element  85   a  disposed on a side of an upper portion of the left buffer  73   a.    
     The left bracket  34   a  is located below the front cover  26  when the vehicle  1  whose body frame  15  is in the upright position is seen from above. 
     The left front wheel  3   a  includes a left front brake  91   a  that generates a braking force of the left front wheel  3   a . The left front brake  91   a  includes a left brake disc  92   a  and a left caliper  93   a . The left brake disc  92   a  has a ring shape around the left wheel shaft  83   a . The left brake disc  92   a  is fixed to the left front wheel  3   a . The left caliper  93   a  is fixed to a lower portion of the left rear telescopic element  80   a  of the left buffer  73   a . An end of a left brake pipe  94   a  is connected to the left caliper  93   a , and the left caliper  93   a  receives a fluid pressure through the left brake pipe  94   a . The left caliper  93   a  causes brake pads to move by the received fluid pressure. The brake pads contact the right side surface and the left side surface of the left brake disc  92   a . The left caliper  93   a  brakes rotation of the left brake disc  92   a  by sandwiching the left brake disc  92   a  between the brake pads. 
       FIG. 11  is a block diagram illustrating a configuration of a brake system  120  included in the vehicle  1 . The brake system  120  includes the left front brake  91   a  and a right front brake  91   b . As previously described with reference to  FIG. 10 , the left front brake  91   a  is provided to the left front wheel  3   a  and generates a braking force of the left front wheel  3   a . The right front brake  91   b  is provided to the right front wheel  3   b  and generates a braking force of the right front wheel  3   b . The left front brake  91   a  corresponds to a “left brake section” and the right front brake  91   b  corresponds to a “right brake section.” The brake system  120  includes a brake actuation device  123 . 
     The brake system  120  includes an input member  121  configured to be operable by the rider driving the vehicle  1 . The input member  121  is in a lever shape, for example. The input member  121  corresponds to a “brake operating element.” 
     The brake system  120  includes a torque control section  100 . The torque control section  100  includes an electronic control unit  101  and a fluid pressure controlling unit  102  actuated by the electronic control unit  101 . 
     The brake actuation device  123  includes a front master cylinder  125 . When the input member  121  is operated by the rider, the front master cylinder  125  is actuated and generates a fluid pressure. The generated fluid pressure is transferred to the torque control section  100  through a front brake pipe  127 . The electronic control unit  101  included in the torque control section  100  controls the fluid pressure controlling unit  102  in order to generate a fluid pressure in accordance with the transferred fluid pressure, the rotation speed of each wheel, a lean state of the vehicle  1 , and so forth. 
     The fluid pressure generated by the fluid pressure controlling unit  102  is transferred to the left caliper  93   a  through a left brake pipe  94   a . Accordingly, the left front brake  91   a  is actuated. Similarly, the fluid pressure generated by the fluid pressure controlling unit  102  is transferred to a right caliper  93   b  through a right brake pipe  94   b . Accordingly, the right front brake  91   b  is actuated. The left brake pipe  94   a  corresponds to a “left pipe” and the right brake pipe  94   b  corresponds to a “right pipe.” 
     The vehicle  1  is configured such that the fluid pressure of brake fluid filling the left brake pipe  94   a  and the fluid pressure of brake fluid filling the right brake pipe  94   b  can be adjusted by the electronic control unit  101  independently of each other. 
     The brake system  120  may include a WC pressure sensor that detects a fluid pressure (fluid pressure of wheel cylinder: WC pressure) of each of the calipers  93   a ,  93   b , and  93   c  of the left front brake  91   a , the right front brake  91   b , and a rear brake  91   c . The electronic control unit  101  can acquire a fluid pressure, that is, a WC pressure, of each brake detected by the WC pressure sensor and can use the acquired pressure for a control process. 
     The fluid pressure controlling unit  102  may include a valve for controlling a flow of a fluid pressure based on operations of the input members  121  and  131 , and a pump for increasing the fluid pressure to be transferred. The fluid pressure controlling unit  102  can control the fluid pressure, that is, a braking torque, of each of the left front brake  91   a , the right front brake  91   b , and the rear brake  91   c  by operating the valve and the pump in accordance with a control signal from the electronic control unit  101 . That is, the fluid pressure controlling unit  102  has a configuration for controlling the fluid pressures of the left front brake  91   a , the right front brake  91   b , and the rear brake  91   c  independently of each other in accordance with control of the electronic control unit  101 . 
     For example, the fluid pressure controlling unit  102  may be configured to include a retention valve, a pump, and a pressure reducing valve, for example. The retention valve controls a flow rate of brake fluid in each of the input members  121  and  131 , the right front brake  91   b , and the left front brake  91   a . The pump increases the fluid pressure of each of the right front brake  91   b  and the left front brake  91   a . The pressure reducing valve reduces the fluid pressure of each of the right front brake  91   b  and the left front brake  91   a . The torque control section  100  controls distribution of the fluid pressure to the right front brake  91   b  and the left front brake  91   a  by controlling operations of the retention valve, the pump, the pressure reducing valve, and other members. A control method for the fluid pressure controlling unit  102  is not limited to a specific method. A method of electrically controlling the fluid pressure, a method combining a fluid pressure pipe and a mechanical valve, and any other method may be employed as a control method for the fluid pressure controlling unit  102 . 
     In the vehicle  1  according to this embodiment, the brake system  120  includes the rear brake  91   c  that generates a braking force of the rear wheel  5 . The brake system  120  includes another input member  131  different from the input member  121 . The brake system  120  includes a brake actuation device  133 . 
     The brake actuation device  133  includes a rear master cylinder  135 . When the input member  131  is operated by the rider, the rear master cylinder  135  is actuated and generates a fluid pressure. The generated fluid pressure is transferred to the torque control section  100  through a rear brake pipe  137 . In a manner similar to the case of operating the input member  121 , the electronic control unit  101  controls the fluid pressure controlling unit  102  in order to generate a fluid pressure in accordance with the transferred fluid pressure, the rotation speed of each wheel, a lean state of the vehicle  1 , and so forth. In the vehicle  1  according to this embodiment, the brake actuation device  133  actuates the right front brake  91   b , the left front brake  91   a , and the rear brake  91   c  by an operation of the input member  131 . That is, the fluid pressure generated by the fluid pressure controlling unit  102  is transferred to the left caliper  93   a  through the left brake pipe  94   a . Accordingly, the left front brake  91   a  is actuated. Similarly, the fluid pressure generated by the fluid pressure controlling unit  102  is transferred to the right caliper  93   b  through the right brake pipe  94   b . Accordingly, the right front brake  91   b  is actuated. Similarly, the fluid pressure generated by the fluid pressure controlling unit  102  is transferred to the rear caliper  93   c  through a rear brake pipe  94   c . Accordingly, the rear brake  91   c  is actuated. 
     In a case where the input member  131  is operated, only the rear brake  91   c  may be actuated. On the other hand, in a case where the input member  121  is operated, the rear brake  91   c  may be actuated in addition to the right front brake  91   b  and the left front brake  91   a.    
     &lt;Posture Control Device&gt; 
       FIG. 12  is a block diagram illustrated an example configuration of the posture control device  200 . The posture control device  200  includes a target yaw moment deviation amount calculating section  201 , a determination section  202 , a side-slip acceleration calculating section  203 , a longitudinal force calculating section  204 , a lateral force calculating section  205 , a yaw moment change rate calculating section  206 , a deviation determination section  207 , and a torque control section  100 .  FIG. 13  is a control flowchart of the posture control device  200 . 
     First Embodiment 
     In the example shown in  FIG. 13 , a target yaw moment deviation amount is calculated (step S 1 ). The target yaw moment deviation amount calculating section  201  calculates a target yaw moment deviation amount based on a side-slip acceleration of each wheel (a front wheel side-slip acceleration (dVf/dt), a rear wheel side-slip acceleration (dVr/dt)), a length if from the vehicle center to the front wheel shaft, a length lr from the vehicle center to the rear wheel shaft, a load of each wheel (a front wheel static load mf, a rear wheel static load mr). 
     The “length from the vehicle center to the front wheel shaft,” the “length form the vehicle center to the rear wheel shaft,” and the “load in each wheel” are static values or dynamic values. 
     A dynamic length lfd from the vehicle center to the front wheel shaft, a dynamic length lrd from the vehicle center to the rear wheel shaft, a dynamic front wheel load mfd, and a dynamic rear wheel load mrd can be obtained as follows: 
     Gx: front and rear accelerations [m/s 2 ] (represented as “+” in acceleration, and “−” in deceleration) 
     lf: static length [m] from the vehicle center to the front wheel shaft 
     lr: static length [m] from the vehicle center to the rear wheel shaft 
     mf: static front wheel load [kg] 
     mr: static rear wheel load [kg] 
     Δmf: front wheel load change rate (the rate of change in a dynamic load with respect to a static load) [kg] 
     Δmr: rear wheel load change rate (the rate of change in a dynamic load with respect to a static load) [kg] 
     m: vehicle total weight [kg] (=mf+mr=mfd+mrd) 
     hgc: static barycenter height [m] 
     θ: roll angle (obtained by the roll angle detecting section  54 ) 
     g: gravitational acceleration [m/s 2 ] 
     l: wheel base (=lf+lr=lfd+lrd) [m] 
     The amount of movement of loads of the front and rear wheels with front and rear acceleration and deceleration are as follows: It should be noted that in the case of front left and right wheels, mf is the sum of the two wheels, whereas in the case of rear left and right wheels, mr is the sum of the two wheels. 
     
       
         
           
             
               
                 
                   
                     
                       Δ 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       
                         m 
                         f 
                       
                     
                     = 
                     
                       
                         - 
                         
                           
                             G 
                             x 
                           
                           g 
                         
                       
                       · 
                       
                         
                           
                             
                               h 
                               gc 
                             
                             · 
                             cos 
                           
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           θ 
                         
                         l 
                       
                       · 
                       m 
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     
                       Δ 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       
                         m 
                         r 
                       
                     
                     = 
                     
                       
                         
                           G 
                           x 
                         
                         g 
                       
                       · 
                       
                         
                           
                             
                               h 
                               gc 
                             
                             · 
                             cos 
                           
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           θ 
                         
                         l 
                       
                       · 
                       m 
                     
                   
                 
               
               
                 
                   [ 
                   
                     Expression 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     2 
                   
                   ] 
                 
               
             
           
         
       
     
     Accordingly, dynamic front and rear wheel loads are as follows:
 
 mfd=mf+Δm   f  
 
 mrd=mr+Δm   r   [Expression 3]
 
     By using these expressions, dynamic distances from the vehicle center to the front and rear wheels can be obtained as: 
     
       
         
           
             
               
                 
                   
                     lfd 
                     = 
                     
                       
                         mrd 
                         m 
                       
                       · 
                       l 
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     lrd 
                     = 
                     
                       
                         mld 
                         m 
                       
                       · 
                       l 
                     
                   
                 
               
               
                 
                   [ 
                   
                     Expression 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     4 
                   
                   ] 
                 
               
             
           
         
       
     
     The side-slip acceleration calculating section  203  calculates a front wheel side-slip acceleration and a rear wheel side-slip acceleration based on a yaw rate, a lean angle (θ) of the vehicle body, a lateral acceleration, and a vehicle body speed calculated by the vehicle speed detecting section  51 . 
     The target yaw moment deviation amount calculating section  201  obtains a target yaw moment deviation amount using the expression below. In the expression, the upper equation represents a case where a target yaw moment deviation amount is obtained using a static value, and the lower equation represents a case where a target yaw moment deviation amount is obtained using a dynamic value. 
     
       
         
           
             
               
                 
                   
                     
                       Δ 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       I 
                       ⁢ 
                       
                         dr 
                         dt 
                       
                     
                     = 
                     
                       
                         
                           l 
                           f 
                         
                         × 
                         
                           
                             dV 
                             f 
                           
                           dt 
                         
                         × 
                         
                           m 
                           f 
                         
                       
                       - 
                       
                         
                           l 
                           r 
                         
                         × 
                         
                           
                             dV 
                             r 
                           
                           dt 
                         
                         × 
                         
                           m 
                           r 
                         
                       
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     
                       Δ 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       I 
                       ⁢ 
                       
                         dr 
                         dt 
                       
                     
                     = 
                     
                       
                         
                           l 
                           fd 
                         
                         × 
                         
                           
                             dV 
                             f 
                           
                           dt 
                         
                         × 
                         
                           m 
                           fd 
                         
                       
                       - 
                       
                         
                           l 
                           
                             r 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             d 
                           
                         
                         × 
                         
                           
                             dV 
                             r 
                           
                           dt 
                         
                         × 
                         
                           m 
                           
                             r 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             d 
                           
                         
                       
                     
                   
                 
               
               
                 
                   [ 
                   
                     Expression 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     5 
                   
                   ] 
                 
               
             
           
         
       
     
     where r (=dΨ/dt) is a yaw rate on a tire ground plane, Vf is a side-slip speed (integral value of a side-slip acceleration) of a front wheel speed, and Vr is a side-slip speed of a rear wheel speed, and ΔI is a yaw moment of inertia (inertia). 
     Next, it is determined whether the target yaw moment deviation amount is less than or equal to a threshold or not (step S 2 ). The determination section  202  determines whether the target yaw moment deviation amount calculated by the target yaw moment deviation amount calculating section  201  is less than or equal to the threshold or not. If the target yaw moment deviation amount is less than or equal to the threshold, a current torque is maintained, and the torque is not modified. 
     If the target yaw moment deviation amount is not less than or equal to the threshold, steps S 3  through S 5  of an optimum solution search loop are performed. This will be described in detail below. 
     In step S 3 , a longitudinal force estimated value and a lateral force estimated value of each wheel when a brake fluid pressure or a driving force is changed is calculated. 
     The longitudinal force calculating section  204  calculates a longitudinal force estimated value in each wheel when the brake fluid pressure (or the driving force) in each wheel is changed. The longitudinal force calculating section  204  uses a value converted from the changed brake fluid pressure as a longitudinal force estimated value, for example. In the case of changing an engine torque (driving force), the longitudinal force calculating section  204  uses a value converted from the changed engine torque as the longitudinal force estimated value, for example. 
     The lateral force calculating section  205  calculates a lateral force estimated value in each wheel when the brake fluid pressure (or the driving force) in each wheel is changed. The lateral force calculating section  205  uses a value converted from the vehicle body roll angle (θ) as the lateral force estimated value, for example. A value of the brake fluid pressure or the engine torque to be changed is a predetermined value at the first time of the loop, and is caused to approach an optimum through repetition of loops. 
     In step S 4 , a yaw moment change rate obtained when the brake fluid pressure (or the driving force) is changed is calculated. The yaw moment change rate calculating section  206  calculates a yaw moment change rate about the vehicle center axis, based on the longitudinal force estimated value in each wheel calculated by the longitudinal force calculating section  204 , the lateral force estimated value in each wheel calculated by the lateral force calculating section  205 , a wheel base, and a tread width. 
     In step S 5 , it is determined whether a deviation between the target yaw moment deviation amount and the yaw moment change rate is less than or equal to a predetermined value or not. The deviation determination section  207  determines whether the deviation between the target yaw moment deviation amount calculated by the target yaw moment deviation amount calculating section  201  and the yaw moment change rate calculated by the yaw moment change rate calculating section  206  is less than or equal to a predetermined value or not. 
     If the deviation determination section  207  determines that the deviation is not less than or equal to the predetermined value, an optimum solution search loop in which the processes of the longitudinal force calculating section  204 , the lateral force calculating section  205 , the yaw moment change rate calculating section  206 , and the deviation determination section  207  are repeated is executed. 
     In step S 6 , if the deviation between the target yaw moment deviation amount and the yaw moment change rate is less than or equal to the predetermined value, a brake fluid pressure (or a driving force) with which a yaw moment change rate can be obtained is used as a control rate. The torque control section  100  controls a torque (a braking force or a driving force) in each wheel, based on a longitudinal force of each wheel and a lateral force of each wheel with which the target yaw moment deviation amount is less than or equal to a threshold. The torque control section  100  controls the control elements so that a torque (a braking force or a driving force) is generated in accordance with these instructions. 
     If the deviation determination section  207  determines that the deviation is less than or equal to the predetermined value, a torque calculating section  208  calculates a torque (a braking force or a driving force) in each wheel that can obtain a yaw moment change rate. For example, the torque calculating section  208  may include a brake fluid pressure calculating section  2081  that calculates a brake fluid pressure in each wheel that can obtain a yaw moment change rate. The torque control section  100  may include a brake fluid pressure control section  1001  that controls a brake fluid pressure in the fluid pressure controlling unit  102 , based on the brake fluid pressure calculated by the brake fluid pressure calculating section  2081 . 
     The torque calculating section  208  may include a driving force calculating section  2082  that calculates a driving force in each wheel that can obtain a yaw moment change rate. The torque control section  100  may include a driving force controlling section  1002  that controls a driving force based on the driving force calculated by the driving force calculating section  2082 . 
     As the optimum solution search loop, the following loop process may be performed. 
     Imon: yaw moment estimated value 
     ΔImon: yaw moment change rate 
     Fx**: longitudinal force estimated value [N] (** represents each wheel, first * represents front [f] or rear [r], and next * represents left [l] or right [r]. e.g., Fxfl is a longitudinal force estimated value of the left front wheel, Fxfr is a longitudinal force estimated value of the right front wheel, Fxrl is a longitudinal force estimated value of the left rear wheel, and Fxrr is a longitudinal force estimated value of the right rear wheel.)
 
Fy**: lateral force estimated value [N] (** represents each wheel, first * represents front [f] or rear [r], and next * represents left [l] or right [r]. e.g., a Fyfl is a lateral force estimated value of the left front wheel, Fyfr is a lateral force estimated value of the right front wheel, Fyrl is a lateral force estimated value of the left rear wheel, and Fyrr is a lateral force estimated value of the right rear wheel.)
 
Itarget: target yaw moment deviation amount (also represented as ΔI·dr/dt)
 
df: tread width [m] of the front left and right wheels
 
dr: tread width [m] of the rear left and right wheels
 
     A yaw moment estimated value Imon at a loop start (first loop or start of repetition) can be calculated using a longitudinal force estimated value and a lateral force estimated value of each wheel as follows: 
     
       
         
           
             
               
                 
                   
                     I 
                     mon 
                   
                   = 
                   
                     
                       
                         l 
                         f 
                       
                       ⁡ 
                       
                         ( 
                         
                           
                             E 
                             yfl 
                           
                           + 
                           
                             F 
                             yfr 
                           
                         
                         ) 
                       
                     
                     - 
                     
                       
                         l 
                         r 
                       
                       ⁡ 
                       
                         ( 
                         
                           
                             F 
                             yrl 
                           
                           + 
                           
                             F 
                             yrr 
                           
                         
                         ) 
                       
                     
                     + 
                     
                       
                         
                           d 
                           f 
                         
                         2 
                       
                       ⁢ 
                       
                         ( 
                         
                           
                             F 
                             xfr 
                           
                           - 
                           
                             F 
                             xfl 
                           
                         
                         ) 
                       
                     
                     + 
                     
                       
                         
                           d 
                           r 
                         
                         2 
                       
                       ⁢ 
                       
                         ( 
                         
                           
                             F 
                             xrr 
                           
                           - 
                           
                             F 
                             xrl 
                           
                         
                         ) 
                       
                     
                   
                 
               
               
                 
                   [ 
                   
                     Expression 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     6 
                   
                   ] 
                 
               
             
           
         
       
     
     For example, when a braking force of the front left wheel is changed, the longitudinal force estimated value and the lateral force estimated value are as follows: In the braking force change rate here, the rate at the first loop is an arbitrary value. 
     (Loop: S 1 ) 
     A longitudinal force change rate is Fxfl+ΔFxfl. 
     A lateral force change rate is Fyfl. In this example, suppose the tires are in a linear range, a lateral force does not change even with a change in a longitudinal force. On the other hand, in a tire non-linear range such as during ABS control, a lateral force may change with a change in a longitudinal force in accordance with μ-s characteristics. 
     A yaw moment change rate Almon in this case is as follows: 
     (Loop: S 2 ) 
     
       
         
           
             
               
                 
                   
                     
                       
                         I 
                         mon 
                       
                       + 
                       
                         Δ 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         
                           I 
                           mon 
                         
                       
                     
                     = 
                     
                       
                         
                           l 
                           f 
                         
                         ⁡ 
                         
                           ( 
                           
                             
                               E 
                               yfl 
                             
                             + 
                             
                               F 
                               yfr 
                             
                           
                           ) 
                         
                       
                       - 
                       
                         
                           l 
                           r 
                         
                         ⁡ 
                         
                           ( 
                           
                             
                               F 
                               yrl 
                             
                             + 
                             
                               F 
                               yrr 
                             
                           
                           ) 
                         
                       
                       + 
                       
                         
                           
                             d 
                             f 
                           
                           2 
                         
                         ⁢ 
                         
                           ( 
                           
                             
                               F 
                               xfr 
                             
                             - 
                             
                               ( 
                               
                                 
                                   F 
                                   xfl 
                                 
                                 + 
                                 
                                   Δ 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   
                                     F 
                                     xfl 
                                   
                                 
                               
                               ) 
                             
                           
                           ) 
                         
                       
                       + 
                       
                         
                           
                             d 
                             r 
                           
                           2 
                         
                         ⁢ 
                         
                           ( 
                           
                             
                               F 
                               xrr 
                             
                             - 
                             
                               F 
                               xrl 
                             
                           
                           ) 
                         
                       
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     
                       Δ 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       
                         I 
                         mon 
                       
                     
                     = 
                     
                       
                         - 
                         
                           
                             d 
                             r 
                           
                           2 
                         
                       
                       ⁢ 
                       
                         ( 
                         
                           Δ 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           
                             F 
                             xfl 
                           
                         
                         ) 
                       
                     
                   
                 
               
               
                 
                   [ 
                   
                     Expression 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     7 
                   
                   ] 
                 
               
             
           
         
       
     
     (Loop: S 3 ) 
     Thereafter, in S 3 , the yaw moment change rate Almon and the target yaw moment deviation amount Itarget are compared. As a result of comparison, if the deviation does not satisfy the condition that the deviation is less than or equal to the predetermined value, the process returns to loop: S 1 . 
     In returning to loop: S 1  (second time or later), a gradient of a deviation between Itarget and ΔImon is calculated. The deviation gradient is a difference between the current loop result (deviation between Itarget and ΔImon) and a previous loop result (in the first loop, a deviation gradient is not calculated). 
     The evaluation of the deviation gradient shows that the deviation is increasing, a change direction (increase or decrease) of a braking force of the front left wheel in the next loop is reversed from the direction in the current loop. On the other hand, the evaluation of the deviation gradient shows that the deviation is decreasing, the change direction of a braking force of the front left wheel is set at the same direction as the direction in the current loop. The degree of a braking force in the next loop is determined based on the value of deviation between Itarget and ΔImon in the current loop and the deviation gradient. Subsequent loops are repeated using the thus-obtained change rate of a braking force of the front left wheel. 
     The foregoing direction is directed to the example of a braking force change in the front left wheel, and a loop process is sequentially performed for the other wheels. For example, the loop process may be performed in the order of the front left wheel, the front right wheel, and the rear wheel. The loop process for each wheel may be performed multiple times, and may continue until the deviation between Itarget and ΔImon reaches the predetermined value or less. 
     In this embodiment, the following posture control can be performed. 
     (1) In turning, a vehicle behavior in turning can be controlled by reducing the absolute value of a longitudinal force in a wheel. For example, an inward-steering moment of the handlebar by front wheel braking is canceled by an outward-steering moment by a difference between braking forces in the front left and right wheels. That is, a steering moment against a steering moment due to the tire shape of the leaning vehicle is generated.
 
(2) In turning, a vehicle behavior in turning can be controlled by increasing the absolute value of a longitudinal force in a wheel. For example, in the absence of a braking operation, a yaw moment is reduced by front wheel braking at generation of a yaw moment by rear wheel side-slip.
 
     Second Embodiment 
     A second embodiment includes the configuration of the first embodiment and is directed to torque control in anti-lock control. 
     The longitudinal force calculating section  204  calculates a longitudinal force estimated value by conversion from a brake fluid pressure at a change in a slip ratio and the slip ratio during anti-lock control. The lateral force calculating section  205  calculates a lateral force estimated value by conversion from a vehicle body roll angle (θ) and a slip ratio during anti-lock control. An optimum solution search loop using the thus-obtained longitudinal force estimated value and lateral force estimated value is performed so that an anti-lock operation of each of the front wheels and the rear wheel can be corrected. 
     In this embodiment, the following posture control can be performed. 
     (1) In turning, a target slip during anti-lock control is changed so that a vehicle behavior in turning can be controlled. For example, while the vehicle body leans because of drift-out, lateral forces of the front wheels are restored and a steering yaw moment is created by changing the slip ratio during anti-lock control. On generation of a yaw moment at spinning, a lateral force of the rear wheel is restored and a yaw moment is reduced by changing the slip ratio during anti-lock control.
 
(2) In straight-ahead traveling (where the road surface μ is different between the left and right wheels), a target slip during anti-lock control is changed so that a vehicle behavior in straight-ahead traveling can be controlled. For example, against a vehicle body moment with a braking force difference among the wheels, braking forces in the wheels are adjusted so as to obtain an optimum vehicle body yaw state (traveling direction).
 
     Third Embodiment 
     A third embodiment includes the configuration of the first or second embodiment and is directed to control of suppression of a tilt motion. 
     The posture control device  200  further includes a suppression section (not shown) that suppresses a tilt motion occurring when the torque control section  100  controls a torque (a braking force or a driving force) in each wheel. The suppression section issues instructions to the tilt mechanism section of the vehicle  1  and suppresses a tilt motion. 
     The tilt mechanism section of the vehicle  1  includes a suppression mechanism for suppressing a tilt motion. Examples the suppression mechanism include a damper that can be electronically controlled, and the damper can suppress a tilt motion by reducing a rotational speed of a linkage mechanism. The tilt motion is suppressed in accordance with instructions from the suppression section of the posture control device  200 . 
     OTHER EMBODIMENTS 
     As another embodiment, the longitudinal force calculating section may estimate a longitudinal force based on a detection value of a throttle sensor and a detection value (brake pressure) of a brake modulator. The lateral force calculating section may calculate a lateral force Ftotal using the equation below, where θ is a roll angle, θ″ is a roll angle acceleration, h is a distance between a barycenter point and an intersection point, Ay is a ground position lateral acceleration, and Ftotal is a lateral force.
 
 F total= m·Δy+m·h ·θ″/cos θ
 
     The ground position lateral acceleration Ay may be calculated based on a lateral acceleration, a roll angle acceleration, a yaw angle acceleration, a roll angle, and a barycenter point of the vehicle. 
     As another embodiment, the brake fluid pressure control section may perform control concerning opening and closing operations of the retention valve and the pressure reducing valve, and control concerning a driving stop operation of the pump. With this configuration, a braking force of each wheel can be changed so that a posture of the vehicle can be controlled by controlling a brake fluid pressure in each wheel. 
     As another embodiment, in a case where the torque control section  100  controls a driving force in each wheel, a wheel-in motor is disposed in at least the front wheels (the front right wheel and the front left wheel), and the torque control section  100  may control the wheel-in motor. 
     As described in the embodiment described above, in a multi-wheel leaning vehicle in which one of the front wheel and the rear wheel includes left and right wheels, a braking torque or a driving torque of each of the front left and right wheels and the rear wheel is controlled, for example. The multi-wheel leaning vehicle travels with the front left and right wheels thereby being traveling on road surfaces having different friction coefficients (including straight-ahead traveling and curve traveling) in some cases. Control is also needed for the posture of the vehicle traveling on such road surfaces in some cases. 
     An anti-lock brake system (ABS) monitors a slip ratio of a vehicle and controls a brake fluid pressure when the slip ratio is before a saturation point of a braking force (in a state where a lateral force is low) (region (a) in  FIG. 14 ). When the ABS is actuated while the vehicle is turning with the body frame leaned in the left direction or in the right direction, the posture of the vehicle is controlled by the remaining lateral direction. As the lean of the body frame during turning of the vehicle increases, a lateral force necessary for posture control increases. Thus, in a case where the ABS is actuated while the vehicle is turning with a large lean (in a state where the lateral force is small), the posture of the vehicle needs to be controlled in some cases. For example, in region (b) in  FIG. 14 , a lateral force necessary for posture control is obtained. 
     In this embodiment, in consideration of the foregoing circumstances, in the leaning vehicle in which one of the front wheel and the rear wheel includes left and right wheels, a posture control device for controlling the posture of the vehicle in straight traveling or turning traveling is provided. 
       FIG. 17  is a view for describing an example motion of the left-right-wheel-equipped leaning vehicle in a case where a friction coefficient (μL) between the left inclined wheel and the road surface and a friction coefficient (μR) between the right inclined wheel and the road surface are different from each other during turning. In the example illustrated in  FIG. 17 , in the vehicle turning rightward, the friction coefficient (μL) between the left front wheel  3   a  and the road surface is larger than the friction coefficient (μR) between the right front wheel  3   b  and the road surface (μR&gt;μL). In this case, a braking force of the left front wheel  3   a  is larger than a braking force of the right front wheel  3   b . That is, a longitudinal force of the left front wheel  3   a  is different from a longitudinal force of the right front wheel  3   b . Accordingly, a leftward yaw moment (yaw rate) is generated in the body frame  15 . Thus, the turning radius increases, and a centrifugal force decreases. Consequently, a roll moment (roll rate) of leaning the body frame  15  rightward, that is, to the inner side of turning, is generated. In this case, the posture control device  200  reduces a braking force of the left front wheel  3   a . Accordingly, a difference between longitudinal forces of the left front wheel  3   a  and the right front wheel  3   b  can be reduced. As a result, the leftward yaw moment is reduced, and a roll moment of leaning the body frame  15  rightward is also reduced. In this manner, the process in which the posture control device  200  reduces a braking force of the left front wheel  3   a  can be achieved by calculating a brake fluid pressure of the left front wheel  3   a  based on target yaw moment deviation amount in the embodiment, for example. 
       FIG. 18  is a view for describing values in calculating a target yaw moment deviation amount in the embodiment. The inventor focused on a phenomenon that in a case where the left-right-wheel-equipped leaning vehicle turns with the left inclined wheel, the right inclined wheel, and the other inclined wheel sufficiently gripping a road surface, the yaw rate and the roll rate of the body frame are substantially uniquely defined relative to each other. By using this phenomenon, in this embodiment, the side-slip acceleration calculating section  203  calculates side-slip accelerations of the left front wheel  3   a  and the right front wheel  3   b  and a side-slip acceleration of the rear wheel  5 , using a yaw rate of the body frame  15  detected by the gyro sensor  53 , a lean angle (roll angle) of the body frame  15  detected by the lean detecting section  50 , and a lateral acceleration detected by the lateral acceleration sensor. The lateral acceleration is an acceleration in the left direction of the body frame or in the right direction of the body frame. 
     For example, the side-slip acceleration calculating section  203  calculates a side-slip acceleration occurring in each wheel, based on an input vehicle body speed V, a roll angle θ of the body frame  15 , a yaw rate, and a lateral acceleration. The side-slip acceleration is calculated by the expression below, as an example. In the expression, dVf/dt is a side-slip acceleration occurring in the front wheels (the left front wheel and the right front wheel in the example described above), dVr/dt is a side-slip acceleration occurring in the rear wheel  5 , and Ay is a detection value of the lateral acceleration sensor attached to the body frame. In addition, Iaf is a horizontal distance between an attachment position of the lateral acceleration sensor and a midpoint of a line connecting the centers of the left front wheel and the right front wheel, Iar is a horizontal distance between an attachment position of the lateral acceleration sensor and the center of the rear wheel, and w is a yaw rate detected by the gyro sensor  53 .
 
 dVf/dt=−V ·ω·sec θ− g ·tan θ+ Ay ·sec θ+ Iaf·dω/dt ·sec θ
 
 dVr/dt=−V ·ω·sec θ− g ·tan θ+ Ay ·sec θ− Iar·dω/dt ·sec θ
 
     In the case of calculating a side-slip acceleration with detection of a roll rate, the calculation is performed based on the equation below, where wr is a detection value of the roll rate.
 
 dVf/dt=−V ·ω·sec θ− g ·tan θ+ Ay ·sec θ+ Iaf·dω/dt ·sec θ+ Iaf·wr ·ω·tan θ·sec θ
 
 dVr/dt=−V ·ω·sec θ− g ·tan θ+ Ay ·sec θ− Iar·dω/dt ·sec θ− Iar·wr ·ω·tan θ·sec θ
 
     Accordingly, a change in a yaw rate due to a decrease of gripping of the left inclined wheel, the right inclined wheel, and the other inclined wheel on the road surface is reflected on side-slip accelerations (dVr/dt) of the left front wheel  3   a  and the right front wheel  3   b  and a side-slip acceleration (dVf/dt) of the rear wheel  5  calculated by the side-slip acceleration calculating section  203  in this embodiment. Using the side-slip accelerations (dVr/dt) and (dVf/dt), a target yaw moment deviation amount is calculated. In this case, the target yaw moment deviation amount may also be regarded as a value indicating a change rate in a yaw moment due to side-slip of the left inclined wheel, the right inclined wheel, and the other inclined wheel. That is, the yaw moment deviation amount in this embodiment is an example of a physical quantity concerning side-slip of the left inclined wheel, the right inclined wheel, and the other inclined wheel. 
     In this embodiment, an operation in which the torque calculating section and the torque control section control torques of the left front wheel  3   a  and the right front wheel  3   b  so as to reduce the target yaw moment deviation amount is an example of an operation in which the leaning posture control device controls a torque of at least one of the right inclined wheel or the left inclined wheel so as to reduce a change in a lean of the body frame  15  in the left direction or in the right direction. 
     The physical quantity concerning side-slip of the left inclined wheel, the right inclined wheel, and the other inclined wheel is not limited to the above example. Side-slip of a wheel is a phenomenon in which the wheel is displaced in the left direction of the vehicle or in the right direction of the vehicle with respect to a road surface. When a force in the left direction of the vehicle or in the right direction of the vehicle is exerted on a wheel while the wheel does not completely grip the road surface, side-slip of the wheel occurs. The physical quantity concerning side-slip of the left inclined wheel, the right inclined wheel, and the other inclined wheel may be a value obtained by detecting a displacement, a speed, or an acceleration of the wheels that actually occurs, and an estimated value of such a displacement, a speed, or an acceleration. The physical quantity concerning side-slip is not limited to a specific value, and may be, for example, a displacement, a speed, an acceleration, an angular velocity, or an angular acceleration, or a value expressed using at least two of these parameters. A method for calculating a physical quantity concerning side-slip of the left inclined wheel, the right inclined wheel, and the other inclined wheel is not limited to the method of the embodiment. For example, a physical quantity concerning side-slip can be acquired by measuring movements of the left inclined wheel, the right inclined wheel, and the other inclined wheel on the road surface with a ground speed meter. In this case, the left-right-wheel-equipped leaning vehicle is configured to include a ground speed meter that directly measures a physical quantity concerning side-slip. 
     In this embodiment, a longitudinal force is the sum of forces exerted on the wheels in the forward direction of the vehicle or in the rearward direction of the vehicle. A lateral force is the sum of forces exerted on the wheels in the left direction of the vehicle or in the right direction of the vehicle. A lateral acceleration is an acceleration in the left direction of the vehicle or in the right direction of the vehicle. The case of simply referring to a lateral acceleration means an acceleration of the body frame in the left direction of the vehicle or in the right direction of the vehicle. 
     The leaning posture control device may control a torque of at least one of the left inclined wheel or the right inclined wheel based on a physical quantity concerning side-slip of the left inclined wheel, the right inclined wheel, and the other inclined wheel, irrespective of an operation of braking or driving the left inclined wheel, the right inclined wheel, or the other inclined wheel by a rider. Accordingly, irrespective of a rider&#39;s operation, posture control can be performed in accordance with side-slip of the left inclined wheel, the right inclined wheel, and the other inclined wheel. For example, while the rider does not perform an operation of braking or driving the left inclined wheel, the right inclined wheel, or the other inclined wheel, the leaning posture control device performs control of making a braking force or a driving force different between the left inclined wheel and the right inclined wheel. 
     Alternatively, with an input of an operation of braking or driving the left inclined wheel, the right inclined wheel, or the other inclined wheel by the rider, the leaning posture control device may control a torque of at least one of the left inclined wheel or the right inclined wheel based on a physical quantity concerning side-slip of the left inclined wheel, the right inclined wheel, and the other inclined wheel, in addition to the rider&#39;s operation. 
     The configuration with which the leaning posture control device controls a torque of at least one of the right inclined wheel or the left inclined wheel based on a physical quantity concerning side-slip of the right inclined wheel, the left inclined wheel, and the other inclined wheel so as to reduce a change in a lean of the lean body frame in the left direction or in the right direction while the lean body frame leans in the left direction or in the right direction is not limited to the configuration of the torque calculating section and the torque control section according to this embodiment. In the above example, the leaning posture control device calculates a braking force or a driving force of the right inclined wheel and a braking force or a driving force of the left inclined wheel that reduce a target yaw rate deviation amount calculated based on side-slip of the right inclined wheel, the left inclined wheel, and the other inclined wheel. 
     As another variation, the leaning posture control device may previously record corresponding data indicating control values corresponding to a plurality of combinations concerning side-slip of the right inclined wheel, the left inclined wheel, and the other inclined wheel. In this case, the leaning posture control device can determine control values corresponding to detected or estimated values concerning side-slip of the right inclined wheel, the left inclined wheel, and the other inclined wheel with reference to the corresponding data. The control value can be, for example, a value indicating a braking force or a driving force of at least one of the right inclined wheel or the left inclined wheel. The format of the corresponding data is not limited to a specific format, and may be formats such as map data and table data. Alternatively, instead of the corresponding data, the leaning posture control device may use a predetermined equation to determine a control value. For example, detected or estimated values concerning side-slip of the right inclined wheel, the left inclined wheel, and the other inclined wheel may be substituted into a predetermined equation to calculate a control value. 
     The embodiment is an example in which the left inclined wheel and the right inclined wheel are front wheels and the other inclined wheel is the rear wheel. The present teaching is also applicable to a left-right-wheel-equipped leaning vehicle in which a left inclined wheel and a right inclined wheel are rear wheels and another inclined wheel is a front wheel. Each of the front wheel and the rear wheel may be constituted by a pair of left and right inclined wheels. 
     The lean detecting section  50  is not limited to the configuration described above. The lean detecting section  50  may be configured to estimate a roll angle by using at least one of a six-axis acceleration or a six-axis speed detected in the vehicle. The lean detecting section  50  may be configured to measure a physical quantity concerning a roll angle of the body frame. The lean detecting section  50  may include a sensor for detecting relative rotation of the body frame and the linkage mechanism, such as a potentiometer. Alternatively, the lean detection section  50  may include a proximity sensor (distance sensor). In this case, the proximity sensor may measure a distance between the body frame and the road surface to estimate a roll angle based on the distance. The left-right-wheel-equipped leaning vehicle and the leaning posture control device for the leaning vehicle according to the present teaching do not necessarily include a lean detecting section. 
     The configuration of the linkage mechanism  9  is not limited to a parallelogram linkage. The linkage mechanism  9  may include a shock tower as an arm that rotates with respect to the body frame, for example. The linkage mechanism  9  may be configured to include a double wishbone frame structure. The linkage mechanism  9  may be configured to include a left arm and a right arm that are arranged in the left-right direction and rotatably attached to the body frame. In this case, the left arm supports the left steering wheel in such a manner that the left steering wheel is movable in the top-bottom direction relative to the body frame, and the right arm supports the right steering wheel in such a manner that the right steering wheel is movable in the top-bottom direction relative to the body frame. 
     The linkage mechanism  9  may include an actuator that applies, to the body frame, a force for rotating the arms. In this manner, a lean of the body frame in the left direction or in the right direction can be controlled by the actuator. In this case, control of the roll moment of the body frame by the leaning posture control device and control of the roll moment by the actuator of the linkage mechanism are combined. 
     The body frame is a member that receives stress on the leaning vehicle during traveling. Examples of the body frame include a monocoque (stressed-skin structure), a semi-monocoque, and a structure in which a vehicle part also serves as a member that receives stress. For example, a part such as an engine or an air cleaner may be a part of the body frame. 
     In the case of controlling driving forces of the left inclined wheel and the right inclined wheel, a driving source such as an electric motor or an engine for driving the left inclined wheel and the right inclined wheel may be provided in the left-right-wheel-equipped leaning vehicle, for example. In the case of the engine, torques of the left inclined wheel and the right inclined wheel can be detected or controlled using the amounts of air and fuel supplied to the engine, a load of the engine, the revolution speed of the engine, and so forth. In the case of the electric motor, torques of the left inclined wheel and the right inclined wheel can be detected or controlled using a current, a voltage, a command value, and so forth supplied to the electric motor. 
     A configuration for controlling braking forces of the left inclined wheel and the right inclined wheel may be the configuration for controlling a brake described above, and a configuration of supplying a braking force by regeneration or reverse driving of an electric motor connected to the left inclined wheel and the right inclined wheel, for example. 
     REFERENCE SIGNS LIST 
     
         
         
           
               100  torque control section 
               200  posture control section 
               201  target yaw moment deviation amount calculating section 
               202  determination section 
               203  side-slip acceleration calculating section 
               204  longitudinal force calculating section 
               205  lateral force calculating section 
               206  yaw moment change rate calculating section 
               207  deviation determination section 
               208  torque calculating section