A new geometric representation for humanoid rehabilitation robot simulation

A humanoid rehabilitation robot, composed of a fixed base, two arms and a waist, is designed to realize the rehabilitation training both on upper and lower extremities, which is described by a forked tree structure with two branches. Conventionally, kinematics and dynamics are analyzed separately in different coordinate frames in order to generate efficient kinematics formulae. It is, however, inconvenient to do simulation at the design stage and to control the robot in the case that inverse dynamics is needed in control schemes, which is worsen with the ever-growing complexity of robot systems. To write kinematics and dynamics in the formal way, a new geometric representation for two consecutive link is proposed, whose features are that a frame is assigned to each link and that the origin is located at the intersection point of two consecutive axles or at the intersection point of the boundary surface of the preceding link and the succeeding axle. With the new geometric representation, the humanoid rehabilitation robot is simulated to select the appropriate combination of harmonic gearboxes and motors in each joint and to do the strength analysis for key components.