Evaluation of dynamic isotropy and coupling acceleration capacity for a parallel manipulator with mixed DoFs

摘要

In dynamic performance evaluation, the indices are generally expected to possess homogeneous units and clear physical meaning. Therefore, dynamic performance evaluation for parallel manipulators with mixed degrees of freedom (DoFs) is challenging. To solve this problem, a method to evaluate the dynamic isotropy and acceleration capacity of parallel manipulators is proposed. The dynamic isotropy of the physical axes is evaluated by deriving the mapping from acceleration to the driving torques. Each acceleration combination is considered to occur with equal probability to cover the complex working condition in an unbiased manner. Under this precondition, the degree of dynamic isotropy is defined for parallel manipulators with mixed DoFs. By mapping the relationship between the driving torque and the acceleration, velocity, gravity, and external load, the kinetic equations can be represented by an inequality group. Through geometric transformation, the acceleration capacity is characterized by the area of the feasible acceleration region. Thereafter, the dynamic isotropy and acceleration capacity of the parallel manipulator are evaluated, and their relationship is further investigated. The proposed indices can be used for workspace identification or motion planning of parallel manipulators. (c) 2021 Elsevier Ltd. All rights reserved.