Redundancy Resolution and Disturbance Rejection via Torque Optimization in Hybrid Cable-Driven Robots

TL;DR

Compared to the existing approaches, this paper provides the first solution (TOAUJ-based method) for HCDRs that can solve the redundancy resolution problem as well as disturbance rejection and develops detailed algorithms targeting TOAJ and TOAUJ implementation.

Abstract

This paper presents redundancy resolution and disturbance rejection via torque optimization in Hybrid Cable-Driven Robots (HCDRs). To begin with, we initiate a redundant HCDR for nonlinear whole-body system modeling and model reduction. Based on the reduced dynamic model, two new methods are proposed to solve the redundancy resolution problem: joint-space torque optimization for actuated joints (TOAJ) and joint-space torque optimization for actuated and unactuated joints (TOAUJ), and they can be extended to other HCDRs. Compared to the existing approaches, this paper provides the first solution (TOAUJ-based method) for HCDRs that can solve the redundancy resolution problem as well as disturbance rejection. Additionally, this paper develops detailed algorithms targeting TOAJ and TOAUJ implementation. A simple yet effective controller is designed for generated data analysis and validation. Case studies are conducted to evaluate the performance of TOAJ and TOAUJ, and the results suggest the effectiveness of the aforementioned approaches.

Figures (8)

• Figure 1: The proposed redundant hybrid cable-driven robot (HCDR) consists of a mobile platform, two 1-DOF pendulums, and a 3-DOF robot arm. (a) Overall structure of HCDR. (b) Enlarge view of the pendulum. (c) Additional parameters assignment of the robot arm and moving platform.
• Figure 2: Cartesian positions and velocities of the end-effector.
• Figure 3: Trajectory responses of the HCDR by given the start point ${\mathbf{p}_{er(i - 1)}}=[0,0.334,0]^T {{~}\rm{m}}$ and the end point ${\mathbf{p}_{eri}}=[0.35,0.5,0.1]^T {{~}\rm{m}}$, where the yellow cube, blue lines, blue circles, and magenta dotted line represent the mobile platform (cables are not displayed here), links of the robot arm, joints of the robot arm, and trajectory of the end-effector, respectively. (a) TOAJ and (b) TOAUJ.
• Figure 4: Redundancy resolution of the actuated joints.
• Figure 5: Force/torque responses of the unactuated joints.