US Patent 7417388 Running machine with wheels

A running machine that can prevent overturning of a body in the case of occurrence of an abnormality is provided. The running machine substantially supports the body with coaxially arranged drive wheels, and can drive while maintaining the balance of the body. A control module of the machine comprises a stabilization controller that computes a first torque command for maintaining the balance of the body and a travel controller that computes a second torque command for driving the running machine. A sum of the first torque command and the second torque command is inputted into the motors. When an abnormal condition detector detects occurrence of an abnormal condition, a safe mode controller prohibits the travel controller from outputting the second torque command. This could enable all torque that the motors can output to be used to maintain the balance of the body when occurrence of an abnormal condition is detected. Therefore, even when occurrence of an abnormal condition is detected, the balance of the body can be maintained. Or even if the balance cannot be maintained, it is possible to extend duration before overturning. During the duration, by pulling out a safety wheel from the body, for instance, overturning of the body can be prevented.