CONTROL DEVICE AND CONTROL METHOD FOR MOTORCYCLIST ASSISTANCE SYSTEM

The invention obtains a controller and a control method capable of improving assistance performance for a rider.In a controller for a rider-assistance system, a speed control execution section executes first speed control operation to adjust a positional relationship between an own vehicle and another vehicle in a disabled state of a group travel mode, executes first automatic control operation to automatically stop the own vehicle or automatically make the own vehicle become a crawl during execution of the first speed control operation, executes second speed control operation to adjust the positional relationship between the own vehicle and another motorcycle in an enabled state of the group travel mode, executes second automatic control operation to automatically stop the own vehicle or automatically make the own vehicle become the crawl during execution of the second speed control operation, and changes behavior of the own vehicle between the first automatic control operation and the second automatic control operation.