In this paper, we discuss the issue of safety in robot-assisted fracture reduction. We define the hazards of robot-assisted fracture reduction and design safety control methods. Although a large reduction force is required to reduce femoral neck fractures, an unexpectedly large force produced by a robot may cause injury to the patient. We have designed two mechanical failsafe units and a software force limiter; this along with velocity control can guarantee a safe operation in reduction force. In addition, to reduce the movement of bone fragments as much as possible, we devised spatially constrained control methods for fracture-reduction robots. The fracture-reduction system was evaluated using simulated fracture reductions.

This paper proposes a prototype of a safe and reliable wheelchair robot with a human-robot interaction. Since the wheelchair is made for mobility aids for the handicapped, the wheelchair robot must guarantee the safety and reliability while considering the user's intention. A single color CCD camera is mounted to input user's command given by human-friendly gestures, and an array of ultrasonic sensors is used for sensing external environment configurations. We use face and hand directional gestures as the input gestures. By combining the sensory environment information with the user's command given by gestures, the planner of the wheelchair robot selects an optimal motion. We present an implemented prototype of the wheelchair robot, MR. HURI, and show experimentally that it is useful for the disabled and the elderly people.