Controller and control method for rider-assistance system

A control method for a rider-assistance system (1) of a motorcycle (100) including:

• a brake system (30) that applies a braking force to a wheel when a rider operates a brake operation section (110);
• and a drive system (40) that applies drive power to the wheel when the rider operates a drive operation section (120), the control method comprising:
• an acquisition step (S101) in which a controller (20) acquires positional relationship information between the motorcycle (100) and another vehicle (200) that travels in front of the motorcycle (100) during travel of the motorcycle (100);
• and
• an execution step (S102, S104, S106) in which the controller (20) executes first speed control operation to control a speed of the motorcycle (100) based on the positional relationship information acquired in the acquisition step (S101) while the rider operates the drive operation section (120), and further comprising:
• a determination step (S103) in which the controller (20) determines presence or absence of necessity to stop the motorcycle (100) or make the motorcycle (100) crawl during the travel of the motorcycle (100), wherein
• in the execution step (S102, S104, S106), in the case where the presence of the necessity is determined in the determination step (S103) during execution of the first speed control operation, the controller (20) executes second speed control operation to automatically generate deceleration to the motorcycle (100) and to stop the motorcycle (100) or make the motorcycle (100) crawl while the rider operates the drive operation section (120).