Variable Stiffness Linear Actuator with Twin Drive Magnetic Lead Screws

Abstract

Magnetic lead screw (MLS) is non-contact feed screw mechanism and possesses elastic characteristic based on magnetic attraction force. An actuator combined with MLS and rotational motor is expected to be used as actuators for robots to support human activities. In this paper, we proposed variable stiffness linear actuator with twin drive magnetic lead screws (TDMLS). It consists of two parallel arranged MLSs and controls the stiffness by adjusting the phase difference between the two rotation angles. We clarify the thrust force characteristics of proposed TDMLS using by 3D-FEM and achieved variable stiffness in the MLS. In addition, it was observed to decrease in maximum thrust force under the stiffness control. However, by using active control of the phase difference, it prevented the reduction of the maximum thrust force.