A Novel Variable Impedance Compact Compliant Series Elastic Actuator: Analysis of Design, Dynamics, Materials and Manufacturing

This paper presents the analysis of electro-mechanical design, selection of materials and manufacturing techniques for physical construction, dynamics, control etc. of a novel variable impedance compact compliant series elastic actuator (SEA) for human-friendly robotics applications. The electro-mechanical design consists of a servomotor, a ball screw, a torsional spring connecting the servomotor and the ball screw via a pair of spur gear, and a set of translational springs connecting the ball screw nut to the output link. The translational springs have low stiffness and these are used to handle low force operations that reduce non-linear friction, output impedance, impact etc. The torsional spring is in the high speed range, has high effective stiffness and it enhances the system bandwidth for large force operations when the translational springs are fully compressed. Suitable materials and appropriate manufacturing techniques for the construction of the actuator are discussed. Kinematics and working principle of the actuator are analyzed. The actuator model is simulated on the physical implementation for dynamics and control for different conditions. Simulation results prove satisfactory performances of the design. Then, advantages of the design over its existing counterparts are discussed, and its potential applications and future extensions are mentioned.