Vibration Regulation of Kinematically Constrained Cable-Driven Parallel Robots With Minimum Number of Actuators

Abstract

Cable-driven parallel robots (CDPRs) provide fast motions over considerably large workspaces, however, they suffer from undesired vibrations. Kinematically constrained CDPRs (KC-CDPRs) are CDPRs that are designed intentionally to have certain kinematic constraints, which help minimizing undesired modes of motion, enhancing stiffness, and hence establishing robustness to external disturbances. This article focuses on the vibration regulation of KC-CDPRs using minimal number of actuators. Considering a generic vibration model with six mode shapes, the effects of configuration of a set of four attachable actuators on energy dissipation of a KC-CDPR system are investigated. Accordingly, a measure is developed to quantify each configuration's capacity of vibration suppression in all six degrees of freedom (DoFs) all over the KC-CDPR workspace. In order to demonstrate the use of the proposed measure, five different actuator configurations are analyzed in detail. Moreover, an optimal proportional–derivative (PD) controller is designed to minimize the maximum settling time of the vibration signals. The proposed actuator configuration effectiveness measure, the provided comparative analysis of configurations, and the proposed optimal PD controller are evaluated and verified to be effective via an experimental KC-CDPR setup, for a planar warehousing case study of vibration regulation in all six DoFs using only four actuators. Comparison of the experimental results of the proposed controller with ${H}_{\infty }$ -based vibration controllers of CDPR demonstrates the superior characteristics of the proposed control technique.