An actuator system for extending and flexing a joint, including a multi-motor assembly for providing a rotational output, a rotary-to-linear mechanism for converting the rotational output from the multi-motor assembly into an extension and flexion of the joint, and a controller for operating the actuator...http://www.google.com.hk/patents/US20100039052?utm_source=gb-gplus-share專利 US20100039052 - ACTUATOR SYSTEM WITH A MULTI-MOTOR ASSEMBLY FOR EXTENDING AND FLEXING A JOINT
