Patent Publication Number: US-2023147892-A1

Title: Controller and control method

Description:
BACKGROUND OF THE INVENTION 
     The present disclosure relates to a controller and a control method for controlling behavior of a straddle-type vehicle. 
     As a conventional technique related to a straddle-type vehicle, a technique of assisting with driving by a rider is available. 
     For example, a system is disclosed in JP-A-2009-116882. Based on information detected by a sensor that detects an obstacle present in a travel direction or substantially in the travel direction, the system warns a rider of the straddle-type vehicle that the straddle-type vehicle inappropriately approaches the obstacle. 
     SUMMARY OF THE INVENTION 
     By the way, in order to assist with driving by the rider, it is considered that a controller performs behavior control operation to automatically decelerate or automatically accelerate the straddle-type vehicle. The controller acquires trigger information during travel of the straddle-type vehicle, and according to the trigger information, initiates a control mode in which the behavior control operation is performed. Here, in the straddle-type vehicle, a center of gravity of the rider himself/herself is significantly shifted during turning travel. In addition, during the turning travel, due to generation of a cornering force, a tire possibly slips even with a slight change in a state amount that relates to a speed. Accordingly, in the case where the straddle-type vehicle turns while the automatic deceleration or the automatic acceleration, which causes the above change, occurs, it may be difficult for the rider to handle a thus-generated change in the behavior of the straddle-type vehicle. 
     The present invention has been made with the above-described problem as the background and therefore obtains a controller and a control method capable of appropriately assisting with driving by a rider. 
     Solution to Problem 
     A controller according to the present invention is a controller controlling behavior of a straddle-type vehicle, and includes: an acquisition section that acquires trigger information during travel of the straddle-type vehicle; and an execution section that initiates a control mode according to the trigger information, in the control mode, behavior control operation to make the straddle-type vehicle automatically decelerate or automatically accelerate being performed. The acquisition section further acquires lateral acceleration information of the traveling straddle-type vehicle. In the control mode, the execution section changes the behavior control operation according to the lateral acceleration information, which is acquired by the acquisition section. 
     A control method according to the present invention is a control method for controlling behavior of a straddle-type vehicle, and includes: an acquisition step in which an acquisition section of a controller acquires trigger information during travel of the straddle-type vehicle; and an execution step in which an execution section of the controller initiates a control mode according to the trigger information, in the control mode, behavior control operation to make the straddle-type vehicle automatically decelerate or automatically accelerate being performed. In the acquisition step, the acquisition section further acquires lateral acceleration information of the traveling straddle-type vehicle. In the execution step, in the control mode, the execution section changes the behavior control operation according to the lateral acceleration information, which is acquired by the acquisition section. 
     Advantageous Effects of Invention 
     In the controller and the control method according to the present invention, the acquisition section acquires the lateral acceleration information of the traveling straddle-type vehicle, and in the control mode in which the behavior control operation to make the straddle-type vehicle automatically decelerate or automatically accelerate is performed, the execution section changes the behavior control operation according to the lateral acceleration information. The lateral acceleration information is information that is closely related to a cornering force generated to the straddle-type vehicle during turning travel. Accordingly, with such control, it is possible to make the straddle-type vehicle automatically decelerate or automatically accelerate while a tendency of a change in a grip characteristic of a tire generated to the straddle-type vehicle during the turning travel is considered, and it is thus possible to appropriately assist with driving by the rider. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a view illustrating an exemplary configuration of a straddle-type vehicle to which a behavior control system according to an embodiment of the present invention is mounted. 
         FIG.  2    is a diagram illustrating an exemplary configuration of the behavior control system according to the embodiment of the present invention. 
         FIG.  3    is a chart illustrating an exemplary processing flow that is executed by a controller in the behavior control system according to the embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     A description will hereinafter be made on a controller and a control method according to the present invention with reference to the drawings. 
     A description will hereinafter be made on a case where a straddle-type vehicle is a two-wheeled motor vehicle. However, the straddle-type vehicle may be another straddle-type vehicle such as a three-wheeled motor vehicle or a bicycle. The straddle-type vehicle means a vehicle that a rider straddles. 
     A configuration, operation, and the like, which will be described below, merely constitute one example. The controller and the control method according to the present invention are not limited to a case with such a configuration, such operation, and the like. In the drawings, the same or similar members or portions will be denoted by the same reference sign or will not be denoted by the reference sign. In addition, a detailed structure will appropriately be illustrated in a simplified manner or will not be illustrated. Furthermore, an overlapping description will appropriately be simplified or will not be made. 
     In the present invention, a term “vehicle body speed” is defined as a concept that includes a speed in the case where the straddle-type vehicle travels forward (that is, a speed as a positive value) and a speed in the case where the straddle-type vehicle travels backward (that is, a speed as a negative value). That is, such expression “an absolute value of the vehicle body speed is increased” means at least one of an increase in the speed in the case where the straddle-type vehicle travels forward and a reduction in the speed in the case where the straddle-type vehicle travels backward. In addition, an expression “the absolute value of the vehicle body speed is reduced” means at least one of the reduction in the speed in the case where the straddle-type vehicle travels forward and the increase in the speed in the case where the straddle-type vehicle travels backward. 
     In the present invention, a term “a differential value of the vehicle body speed” is defined as a concept that includes acceleration in the case where the vehicle body speed of the straddle-type vehicle is increased (that is, acceleration as a positive value) and acceleration in the case where the vehicle body speed of the straddle-type vehicle is reduced (that is, acceleration as a negative value). That is, an expression “an absolute value of the differential value of the vehicle body speed is increased” means at least one of an increase in the acceleration in the case where the vehicle body speed of the straddle-type vehicle is increased and a reduction in the acceleration in the case where the vehicle body speed of the straddle-type vehicle is reduced. In addition, an expression “the absolute value of the differential value of the vehicle body speed is reduced” means at least one of the reduction in the acceleration in the case where the vehicle body speed of the straddle-type vehicle is increased and the increase in the acceleration in the case where the vehicle body speed of the straddle-type vehicle is reduced. 
     In the present invention, a term “a second-order differential value of the vehicle body speed” is defined as a concept that includes jerk in the case where the differential value of the vehicle body speed of the straddle-type vehicle is increased (that is, jerk as a positive value) and jerk in the case where the differential value of the vehicle body speed of the straddle-type vehicle is reduced (that is, jerk as a negative value). That is, an expression “an absolute value of the second-order differential value of the vehicle body speed is increased” means at least one of an increase in the jerk in the case where the differential value of the vehicle body speed of the straddle-type vehicle is increased and a reduction in the jerk in the case where the differential value of the vehicle body speed of the straddle-type vehicle is reduced. In addition, an expression “the absolute value of the second-order differential value of the vehicle body speed is reduced” means at least one of the reduction in the jerk in the case where the differential value of the vehicle body speed of the straddle-type vehicle is increased and the increase in the jerk in the case where the differential value of the vehicle body speed of the straddle-type vehicle is reduced. 
     &lt;Configuration of Behavior Control System&gt; 
     A description will be made on a configuration of a behavior control system according to an embodiment of the present invention. 
       FIG.  1    is a view illustrating an exemplary configuration of the straddle-type vehicle to which he behavior control system according to the embodiment of the present invention is mounted.  FIG.  2    is a diagram illustrating an exemplary configuration of the behavior control system according to the embodiment of the present invention. 
     As illustrated in  FIG.  1   , a behavior control system  10  is mounted to a straddle-type vehicle  100 . The straddle-type vehicle  100  includes: a trunk  1 ; a handlebar  2  that is held by the trunk  1  in a freely turnable manner; a front wheel  3  that is held by the trunk  1  in a freely turnable manner with the handlebar  2 ; and a rear wheel  4  that is held by the trunk  1  in a freely rotatable manner. 
     For example, the behavior control system  10  includes: a drive mechanism  11  for generating a propelling force, which corresponds to at least an operation amount of a drive operation section  11   a  by the rider, to the rear wheel  4 ; a front-wheel brake mechanism  12  that brakes the front wheel  3  with a braking force that corresponds to at least an operation amount of a front-wheel brake operation section  12   a  by the rider; and a rear-wheel brake mechanism  13  that brakes the rear wheel  4  with a braking force that corresponds to at least an operation amount of a rear-wheel brake operation section  13   a  by the rider. 
     For example, the drive mechanism  11  may have an engine as a drive source or may have another mechanism such as a motor as the drive source. For example, the drive operation section  11   a  may be a throttle grip that is provided to the handlebar  2  of the straddle-type vehicle  100  or may be an accelerator pedal that is provided to the trunk  1  of the straddle-type vehicle  100 . In addition, the drive mechanism  11  may generate the propelling force, which corresponds to at least the operation amount of the drive operation section  11   a  by the rider, to the front wheel  3 . 
     For example, the drive mechanism  11  is configured to be able to automatically generate the propelling force and increase or reduce the propelling force in a state where an operation of the drive operation section  11   a  by the rider is absent. The drive mechanism  11  may be configured to be able to automatically increase or reduce the propelling force in a state where the rider operates the drive operation section  11   a  and the operation amount thereof is maintained to be constant. That is, the drive mechanism  11  is configured to be able to make the straddle-type vehicle  100  automatically accelerate or automatically decelerate. 
     The front-wheel brake mechanism  12  and the rear-wheel brake mechanism  13  may be independent from each other. Alternatively, both of the front-wheel brake mechanism  12  and the rear-wheel brake mechanism  13  may generate the braking forces according to the operation amount of one of the front-wheel brake operation section  12   a  and the rear-wheel brake operation section  13   a  by the rider. Each of the front-wheel brake operation section  12   a  and the rear-wheel brake operation section  13   a  may be a brake lever that is provided to the handlebar  2  of the straddle-type vehicle  100  or may be a brake pedal that is provided to the trunk  1  of the straddle-type vehicle  100 , for example. Only one of the front-wheel brake mechanism  12  and the rear-wheel brake mechanism  13  may be provided to the straddle-type vehicle  100 . 
     For example, at least one of the front-wheel brake mechanism  12  and the rear-wheel brake mechanism  13  is configured to be able to automatically generate the braking force and to increase or reduce the braking force in a state where the operation of the front-wheel brake operation section  12   a  and the rear-wheel brake operation section  13   a  by the rider is absent. At least one of the front-wheel brake mechanism  12  and the rear-wheel brake mechanism  13  may be configured to be able to automatically increase or reduce a total braking force generated to the straddle-type vehicle  100  in a state where the rider operates at least one of the front-wheel brake operation section  12   a  and the rear-wheel brake operation section  13   a  and the operation amount is maintained to be constant. That is, at least one of the front-wheel brake mechanism  12  and the rear-wheel brake mechanism  13  is configured to be able to make the straddle-type vehicle  100  automatically decelerate or automatically accelerate. 
     As illustrated in  FIG.  1    and  FIG.  2   , the behavior control system  10  includes a front-wheel rotational frequency sensor  41 , a rear-wheel rotational frequency sensor  42 , an inertial measurement unit (IMU)  43 , an environment information collector  44 , and an input device  45 , for example. The front-wheel rotational frequency sensor  41 , the rear-wheel rotational frequency sensor  42 , the IMU  43 , the environment information collector  44 , and the input device  45  can communicate with a controller (ECU)  60 . The controller  60  may be provided as one unit or may be divided into multiple units. In addition, the controller  60  may partially or entirely be constructed of a microcomputer, a microprocessor unit, or the like, may be constructed of a member in which firmware or the like can be updated, or may be a program module or the like that is executed by a command from a CPU or the like, for example. 
     The front-wheel rotational frequency sensor  41  detects rotational frequency information of the front wheel  3 , and outputs a detection result. The front-wheel rotational frequency sensor  41  may detect, as the rotational frequency information of the front wheel  3 , a rotational frequency itself or may detect another physical quantity that can substantially be converted into the rotational frequency. The rear-wheel rotational frequency sensor  42  detects rotational frequency information of the rear wheel  4 , and outputs a detection result. The rear-wheel rotational frequency sensor  42  may detect, as the rotational frequency information of the rear wheel  4 , a rotational frequency itself or may detect another physical quantity that can substantially be converted into the rotational frequency. 
     The IMU  43  includes a three-axis gyroscope sensor and a three-directional acceleration sensor, for example. The IMU  43  is provided to the trunk  1 , for example. The IMU  43  at least detects information on lateral acceleration that is generated to the straddle-type vehicle  100 , and outputs a detection result. The lateral acceleration is defined as acceleration in a direction that is orthogonal to a vertical axis or a road surface perpendicular axis passing through a center of gravity of the straddle-type vehicle  100  and that is orthogonal to a longitudinal direction or an advancing direction of the straddle-type vehicle  100  or as acceleration in a direction that is orthogonal to a parallel axis with a vehicle height direction passing through the center of gravity of the straddle-type vehicle  100  and that is orthogonal to the longitudinal direction or the advancing direction of the straddle-type vehicle  100 . Alternatively, the lateral acceleration may be defined as the acceleration in the direction that is orthogonal to the vertical axis or the road surface perpendicular axis and that is orthogonal to the longitudinal direction or the advancing direction of the straddle-type vehicle  100 , and a positional relationship of the acceleration with the center of gravity of the straddle-type vehicle  100  passes through a known point. Further alternatively, the lateral acceleration may be defined as the acceleration in the direction that is orthogonal to the parallel axis with the vehicle height direction and that is orthogonal to the longitudinal direction or the advancing direction of the straddle-type vehicle  100 , and the positional relationship of the acceleration with the center of gravity of the straddle-type vehicle  100  passes through a known point. The IMU  43  may detect the lateral acceleration itself as the lateral acceleration information or may detect another physical quantity that can substantially be converted into the lateral acceleration. For example, the IMU  43  may detect, as the lateral acceleration information, another acceleration or a rotational angular velocity from which the lateral acceleration can be derived. That is, any IMU can be adopted as the IMU  43  as long as the IMU can acquire the lateral acceleration information that is defined as information from which the lateral acceleration generated to the straddle-type vehicle  100  can be derived. In addition, the IMU  43  may not be provided in the case where a system other than the behavior control system  10  can acquire the lateral acceleration information. 
     The environment information collector  44  collects environment information around the straddle-type vehicle  100 , and outputs a result. For example, the environment information collector  44  collects positional relationship information of a target with the straddle-type vehicle  100 . The target (for example, another vehicle, an object that becomes an obstacle, a person or an animal that becomes the obstacle, a road facility, a road surface defect, or the like) is located in front of, behind, or on a side of the straddle-type vehicle  100 , for example. For example, the positional relationship information includes relative distance information, relative speed information, relative acceleration information, and the like. For example, the environment information collector  44  is a distance measurement sensor (for example, a Lidar, a radar, an ultrasonic sensor, or the like), a camera, or the like that is attached to the straddle-type vehicle  100  in a state of facing the front, the rear, or the side thereof. The environment information collector  44  may be a wireless communicator that receives information from the other vehicle or the road facility wirelessly. For example, the wireless communicator receives the positional relationship information of the target that is located in front of, behind, or on the side of the straddle-type vehicle  100 , travel state information of the other vehicle that is located in front of, behind, or on the side of the straddle-type vehicle  100 , traffic sign information of a road where the straddle-type vehicle  100  travels, traffic condition information of the road where the straddle-type vehicle  100  travels, and the like. 
     The input device  45  accepts an operation to validate or set a travel mode that is desired by the rider. For example, the input device  45  accepts, as the travel mode, an operation to validate or set adaptive cruise control as one type of cruise control, an operation to validate or set emergency operation for avoidance of a collision, an operation to validate or set haptic motion for warning the rider, or the like. As the input device  45 , a lever, a button, a touchscreen, or the like is used, for example. The input device  45  is provided to the handlebar  2 , for example. 
     The cruise control is the travel mode that makes the straddle-type vehicle  100  automatically decelerate or automatically accelerate such that the vehicle body speed of the straddle-type vehicle  100  approximates a speed reference value. Auto-cruise control is the travel mode that makes the straddle-type vehicle  100  automatically decelerate or automatically accelerate such that the vehicle body speed of the straddle-type vehicle  100  is maintained to be lower than the speed reference value by the cruise control and that a distance from the straddle-type vehicle  100  to a preceding vehicle approximates a distance reference value. The speed reference value and the distance reference value can appropriately be set by the rider. The vehicle body speed of the straddle-type vehicle  100  may be acquired on the basis of the rotational frequencies of the front wheel  3  and the rear wheel  4  or may be acquired on the basis of the detection result by the other sensor. That is, any sensor can be adopted as long as a sensor for detecting the vehicle body speed can acquire vehicle body speed information that is defined as information from which the vehicle body speed generated to the straddle-type vehicle  100  can be derived. In addition, such a sensor may not be provided in the case where the system other than the behavior control system  10  can acquire the vehicle body speed information. 
     The emergency operation for the avoidance of the collision is the travel mode that makes the straddle-type vehicle  100  automatically decelerate or automatically accelerate emergently in the case where a collision possibility of the straddle-type vehicle  100  with the target, which is located in front of, behind, or on the side of the straddle-type vehicle  100 , is high. The collision possibility can be acquired on the basis of at least one of the relative distance information, the relative speed information, and the relative acceleration information of the straddle-type vehicle  100  to the target. In addition, a determination reference value of the collision possibility can appropriately be set by the rider. Furthermore, the automatic deceleration or the automatic acceleration may not be deceleration or acceleration with which the collision can reliably be prevented, and suffices as long as the avoidance of the collision by the rider can be assisted thereby. 
     The haptic motion to inform the rider with the warning is a travel mode that makes the straddle-type vehicle  100  automatically decelerate or automatically accelerate instantaneously. Examples of the warning are: a warning that informs the rider that the emergency operation is performed to avoid the collision; the warning that urges the rider to perform a setting operation of the travel mode; a warning that informs the rider of existence of the other vehicle in a particular travel state; a warning that urges the rider to pay attention to the traffic sign on the road where the straddle-type vehicle  100  travels; a warning that informs the rider of existence of a particular traffic condition (for example, traffic jam, a disabled vehicle, roadwork, or the like) ; and a warning that informs the rider of a particular state of the straddle-type vehicle  100 . The automatic deceleration or the automatic acceleration may occur only once or may be repeated for plural times. 
     The controller  60  outputs a control command to at least one of the drive mechanism  11 , the front-wheel brake mechanism  12 , and the rear-wheel brake mechanism  13  so as to control behavior of the straddle-type vehicle  100 . The controller  60  includes an acquisition section  61  and an execution section  62 . 
     During travel of the straddle-type vehicle  100 , the acquisition section  61  acquires the information that is output from the front-wheel rotational frequency sensor  41 , the rear-wheel rotational frequency sensor  42 , the IMU  43 , the environment information collector  44 , and the input device  45 , and based on those types of the information, determines whether it is necessary to make the straddle-type vehicle  100  automatically decelerate or automatically accelerate. In the case where it is necessary, the acquisition section  61  outputs, as trigger information, information thereon to the execution section  62 . The acquisition section  61  determines such a necessity per validated travel mode. The trigger information is defined as information that serves as a trigger to initiate a control mode in which behavior control operation to make the straddle-type vehicle  100  automatically decelerate or automatically accelerate is performed. 
     When receiving the trigger information, the execution section  62  initiates the control mode, in which the behavior control operation to make the straddle-type vehicle  100  automatically decelerate or automatically accelerate is performed. When making the straddle-type vehicle  100  automatically decelerate or increasing or reducing the deceleration, the execution section  62  may control the braking force of the straddle-type vehicle  100  (that is, at least one of the front-wheel brake mechanism  12  and the rear-wheel brake mechanism  13 ), or may control the propelling force of the straddle-type vehicle  100  (that is, the drive mechanism  11 ). In addition, when making the straddle-type vehicle  100  automatically accelerate or increasing or reducing the acceleration thereof, the execution section  62  may control the propelling force of the straddle-type vehicle  100  (that is, the drive mechanism  11 ), or may control the braking force of the straddle-type vehicle  100  (that is, at least one of the front-wheel brake mechanism  12  and the rear-wheel brake mechanism  13 ). 
     Here, in the control mode, the execution section  62  changes the behavior control operation according to the lateral acceleration information, which is acquired by the acquisition section  61 . 
     As an example, in the control mode, when causing the generation of the automatic deceleration or the automatic acceleration, the execution section  62  changes the second-order differential value of the vehicle body speed, which is generated to the straddle-type vehicle  100 , according to the lateral acceleration information, which is acquired by the acquisition section  61 . The execution section  62  may execute control of the second-order differential value only at an initiation of the automatic deceleration or the automatic acceleration or, in addition thereto or instead thereof, may execute the control of the second-order differential value during the automatic deceleration or the automatic acceleration. For example, in the behavior control operation that causes the automatic deceleration, in the case where the lateral acceleration information is information indicating that the high lateral acceleration is generated to the straddle-type vehicle  100 , the execution section  62  reduces the absolute value of the second-order differential value to be smaller than that in the case where the lateral acceleration information is information indicating that the low lateral acceleration is generated to the straddle-type vehicle  100 . For example, in the behavior control operation that causes the automatic acceleration, in the case where the lateral acceleration information is information indicating that the high lateral acceleration is generated to the straddle-type vehicle  100 , the execution section  62  reduces the absolute value of the second-order differential value to be smaller than that in the case where the lateral acceleration information is information indicating that the low lateral acceleration is generated to the straddle-type vehicle  100 . A degree of a reduction in the absolute value of the second-order differential value may appropriately be set by the rider. 
     As an example, in the control mode, in the case where the lateral acceleration information, which is acquired by the acquisition section  61 , is information indicating that the lateral acceleration exceeding a reference value is generated to the straddle-type vehicle  100 , the execution section  62  cancels the behavior control operation. That is, the execution section  62  does not make the straddle-type vehicle  100  automatically decelerate or automatically accelerate. The execution section  62  may cancel the behavior control operation only at the initiation of the automatic deceleration or the automatic acceleration or, in addition thereto or instead thereof, may cancel the behavior control operation during the automatic deceleration or the automatic acceleration. Upon the cancellation, the execution section  62  may continue the control mode in a state where the straddle-type vehicle  100  does not automatically decelerate or automatically accelerate, may cancel the control mode itself, or may control the travel mode itself that requires the automatic deceleration or the automatic acceleration. After canceling the behavior control operation, the execution section  62  may keep canceling the behavior control operation until input of the trigger information is stopped (that is, the acquisition section  61  determines that the automatic deceleration or the automatic acceleration is unnecessary), or may resume the behavior control operation (that is, the automatic deceleration or the automatic acceleration) as long as the acquisition section  61  acquires the lateral acceleration information indicating that the lateral acceleration falling below the reference value is generated to the straddle-type vehicle  100  under a situation where the input of the trigger information continues (that is, the acquisition section  61  keeps determining that the automatic deceleration or the automatic acceleration is necessary). The reference value that is used for the determination on the cancellation of the behavior control operation and the reference value that is used for the determination on the resumption of the behavior control operation thereafter may be the same or may differ from each other. In addition, those reference values may appropriately be set by the rider. 
     In the control mode, the execution section  62  may further change the behavior control operation according to the vehicle body speed information, which is acquired by the acquisition section  61 . For example, only in the case where the vehicle body speed information is information indicating that the vehicle body speed exceeding a reference value is generated to the straddle-type vehicle  100 , the execution section  62  may change the behavior control operation according to the lateral acceleration information, which is acquired by the acquisition section  61 . In addition, for example, in the case where the vehicle body speed information is information indicating that the high vehicle body speed is generated to the straddle-type vehicle  100 , the execution section  62  may increase a change in the absolute value of the second-order differential value, which corresponds to the lateral acceleration information acquired by the acquisition section  61 , to be larger than that in the case where the vehicle body speed information is the information indicating that the low vehicle body speed is generated to the straddle-type vehicle  100 . 
     &lt;Operation of Behavior Control System&gt; 
     A description will be made on operation of the behavior control system according to the embodiment of the present invention. 
       FIG.  3    is a chart illustrating an exemplary processing flow that is executed by the controller in the behavior control system according to the embodiment of the present invention. 
     The controller  60  repeatedly executes the control flow illustrated in  FIG.  3    during the travel of the straddle-type vehicle  100 . 
     (Acquisition Step) 
     In step S 101 , the acquisition section  61  of the controller  60  determines whether it is necessary to make the straddle-type vehicle  100  automatically decelerate or automatically accelerate. In the case where it is necessary, the processing proceeds to step S 102 , and the acquisition section  61  outputs, as the trigger information, the information thereon to the execution section  62 . If it is not necessary, the processing flow returns to step S 101 . 
     (Execution Step) 
     When the trigger information is output in step S 102 , in step S 103 , the execution section  62  of the controller  60  initiates the control mode, in which the behavior control operation to make the straddle-type vehicle  100  automatically decelerate or automatically accelerate is performed. Here, in the control mode, the execution section  62  changes the behavior control operation according to the lateral acceleration information, which is acquired by the acquisition section  61 . When the execution section  62  terminates a series of the operation in the control mode, the processing flow returns to step S 101 . 
     &lt;Effects of Behavior Control System&gt; 
     A description will be made on effects of the behavior control system according to the embodiment of the present invention. 
     In the behavior control system  10 , the acquisition section  61  acquires the lateral acceleration information of the traveling straddle-type vehicle  100 , and in the control mode in which the behavior control operation to make the straddle-type vehicle  100  automatically decelerate or automatically accelerate is performed, the execution section  62  changes the behavior control operation according to the lateral acceleration information. The lateral acceleration information is information that is closely related to the cornering force generated to the straddle-type vehicle  100  during the turning travel. Accordingly, with such control, it is possible to make the straddle-type vehicle  100  automatically decelerate or automatically accelerate while a tendency of a change in a grip characteristic of the tire generated to the straddle-type vehicle  100  during the turning travel is considered, and it is thus possible to appropriately assist with driving by the rider. 
     Preferably, in the behavior control system  10 , when causing the generation of the automatic deceleration or the automatic acceleration, the execution section  62  changes the second-order differential value of the vehicle body speed, which is generated to the straddle-type vehicle  100 , according to the lateral acceleration information, which is acquired by the acquisition section  61 . In the case where a significant change in the acceleration, which is not expected by the rider, occurs due to the generation of the automatic deceleration or the automatic acceleration during the turning travel of the straddle-type vehicle  100 , it is especially difficult for the rider to handle the thus-generated change in the behavior of the straddle-type vehicle  100 . Therefore, with such control, driving by the rider is further appropriately assisted. 
     Preferably, in the behavior control system  10 , during the automatic deceleration or the automatic acceleration, the execution section  62  changes the second-order differential value of the vehicle body speed, which is generated to the straddle-type vehicle  100 , according to the lateral acceleration information, which is acquired by the acquisition section  61 . In the case where the significant change in the acceleration occurs at the time when the straddle-type vehicle  100  is shifted to the turning travel from the automatic deceleration or the automatic acceleration, it is especially difficult for the rider to handle the thus-generated change in the behavior of the straddle-type vehicle  100 . Therefore, with such control, driving by the rider is further appropriately assisted. 
     In particular, in the case where the behavior control operation is the operation that makes the straddle-type vehicle  100  automatically decelerate, and the lateral acceleration information is the information indicating that the high lateral acceleration is generated to the straddle-type vehicle  100 , the execution section  62  preferably reduces the absolute value of the second-order differential value of the vehicle body speed to be smaller than that in the case where the lateral acceleration information is the information indicating that the low lateral acceleration is generated to the straddle-type vehicle  100 . In the case where the lateral acceleration information is the information indicating that the high lateral acceleration is generated to the straddle-type vehicle  100 , it is possible to assume that a current situation is the situation where the large cornering force is generated to the straddle-type vehicle  100  during the turning travel. In the case where the significant change occurs to the acceleration at the initiation of the automatic deceleration or during the automatic deceleration in such a situation, the tire possibly slips. For this reason, with such control, the significant change in the acceleration is suppressed, and driving by the rider is further appropriately assisted by the automatic deceleration. 
     In particular, in the case where the behavior control operation is the operation that makes the straddle-type vehicle  100  automatically accelerate, and the lateral acceleration information is the information indicating that the high lateral acceleration is generated to the straddle-type vehicle  100 , the execution section  62  preferably reduces the absolute value of the second-order differential value of the vehicle body speed to be smaller than that in the case where the lateral acceleration information is the information indicating that the low lateral acceleration is generated to the straddle-type vehicle  100 . In the case where the lateral acceleration information is the information indicating that the high lateral acceleration is generated to the straddle-type vehicle  100 , it is possible to assume that a current situation is the situation where the large cornering force is generated to the straddle-type vehicle  100  during the turning travel. In the case where the significant change occurs to the acceleration at the initiation of the automatic acceleration or during the automatic acceleration in such a situation, the tire possibly slips. For this reason, with such control, the significant change in the acceleration is suppressed, and driving by the rider is further appropriately assisted by the automatic acceleration. 
     Preferably, in the behavior control system  10 , in the case where the lateral acceleration information, which is acquired by the acquisition section  61 , is the information indicating that the lateral acceleration exceeding the reference value is generated to the straddle-type vehicle  100 , the execution section  62  cancels the behavior control operation. With such control, under a situation where the tire is likely to slip, the travel of the straddle-type vehicle  100  that automatically decelerates or automatically accelerates is suppressed. As a result, driving by the rider is further appropriately assisted. 
     In particular, during the cancellation of the behavior control operation, in the case where the lateral acceleration information, which is acquired by the acquisition section  61 , is the information indicating that the lateral acceleration falling below the reference value is generated to the straddle-type vehicle  100 , the execution section  62  preferably performs the behavior control operation. With such control, unnecessary restriction of the automatic deceleration or the automatic acceleration is suppressed. As a result, driving by the rider is further appropriately assisted. 
     Preferably, in the behavior control system  10 , the acquisition section  61  acquires the information on the vehicle body speed generated to the traveling straddle-type vehicle  100 , and the execution section  62  further changes the behavior control operation according to the vehicle body speed information. With such control, the straddle-type vehicle  100  can automatically decelerate or automatically accelerate while an impact of the slip of the tire is considered. As a result, driving by the rider is further appropriately assisted. 
     The present invention is not limited to the embodiment that has been described. For example, only a part of the embodiment may be implemented, or parts of the embodiment may be combined. In addition, an order of the steps may be switched, for example. 
     For example, when the execution section  62  causes the automatic deceleration or the automatic acceleration, in addition to or instead of changing the second-order differential value of the vehicle body speed, which is generated to the straddle-type vehicle  100 , according to the lateral acceleration information, which is acquired by the acquisition section  61 , at least one of the vehicle body speed and the differential value may be changed according to the lateral acceleration information, which is acquired by the acquisition section  61 . The execution section  62  may execute such control only at the initiation of the automatic deceleration or the automatic acceleration or, in addition thereto or instead thereof, may execute the control during the automatic deceleration or the automatic acceleration. For example, in the behavior control operation that causes the automatic deceleration, in the case where the lateral acceleration information is the information indicating that the high lateral acceleration is generated to the straddle-type vehicle  100 , the execution section  62  reduces the absolute value of the vehicle body speed or the absolute value of the differential value of the vehicle body speed to be smaller than that in the case where the lateral acceleration information is the information indicating that the low lateral acceleration is generated to the straddle-type vehicle  100 . In addition, for example, in the behavior control operation that causes the automatic acceleration, in the case where the lateral acceleration information is the information indicating that the high lateral acceleration is generated to the straddle-type vehicle  100 , the execution section  62  reduces the absolute value of the vehicle body speed or the absolute value of the differential value of the vehicle body speed to be smaller than that in the case where the lateral acceleration information is the information indicating that the low lateral acceleration is generated to the straddle-type vehicle  100 . The degree of the reduction in the absolute value may appropriately be set by the rider. Furthermore, in the case where the vehicle body speed information is the information indicating that the high vehicle body speed is generated to the straddle-type vehicle  100 , the execution section  62  may increase the change in the absolute value to be larger than that in the case where the vehicle body speed information is the information indicating that the low vehicle body speed is generated to the straddle-type vehicle  100 . 
     REFERENCE SIGNS LIST 
       1 : Trunk 
       2 : Handlebar 
       3 : Front wheel
   4 : Rear wheel
   10 : Behavior control system
   11 : Drive mechanism
   11   a : Drive operation section
   12 : Front-wheel brake mechanism
   12   a : Front-wheel brake operation section
   13 : Rear-wheel brake mechanism
   13   a : Rear-wheel brake operation section
   41 : Front-wheel rotational frequency sensor
   42 : Rear-wheel rotational frequency sensor
   43 : Inertial measurement unit
   44 : Environment information collector
   45 : Input device
 
       60 : Controller 
       61 : Acquisition section
   62 : Execution section
   100 : Straddle-type vehicle