Optimization-Based Investigation of Bioinspired Variable Gearing of the Distributed Actuation Mechanism to Maximize Velocity and Force

Transmission between high speed and high force motions is a classic, but challenging problem for most engineering disciplines as well as robotics. This study optimizes the performances (i.e., both velocity and force) of the distributed actuation mechanism (DAM) based on the novel concept of continuously variable gearing, which is inspired by muscle movement. To quantify continuously variable gearing in the DAM, the structural gear ratio (defined as joint speed/motor speed) is mathematically derived in terms of the slider position and the joint angle. Then, for a DAM-based three-revolute joint manipulator, a multi-objective optimization problem is formulated to determine the maximum end-effector velocity according to varying payloads. An optimization framework consisting of the analysis and optimization modules is constructed to verify the proposed concept with a comparison of an equivalent joint actuation mechanism (JAM)-based three-revolute joint manipulator. The numerical results demonstrate that the bioinspired variable gearing of the DAM allows for a significant enhancement of end-effector velocity and force, depending on a given task.