Design and wrench-feasible workspace analysis of a cable-driven hybrid joint

Abstract

This article proposes a cable-driven hybrid joint (CDHJ), focuses on the effects of external wrench payload and structural parameters on the wrench-feasible workspace for the preliminary design of the mechanism, and further discusses the wrench exertion capability of the mechanism under a certain configuration. This CDHJ has central rigid support with a revolute pair and a central compression spring support. Due to the unilateral property of cables and the flexible compression spring, the kinematic model cannot define the workspace directly; it should be combined with the statics for possible solution, including the spring lateral buckling model based on the elliptic integral solution. Moreover, a global tension index which is to evaluate the wrench-closure property of the global workspace, combined with an index which is to assess the size of the workspace, is proposed to better compare the effects of different external wrench payloads and different structural parameters on the workspace. Simulations were performed and demonstrated the correctness and feasibility of the inverse kinematics and workspace analysis of the joint. Hence, the proposed mechanism has potential use in robotics especially in wheelchair-mounted robotic manipulator joint.

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“…Cable robots represent arguably the most lightweight configuration for a manipulative system, which is particularly valuable for UAVs [243]. Dr. Zhaokun Zhang has designed a cable-driven parallel robot with three sets of cables and a central spring rod that can achieve higher speeds, more precise control, lighter weight, and lower energy consumption than delta parallel robots [244][245][246][247][248][249], as shown in Figure 16. The innovation of the design is the use of retractable spring rods to keep the cable taut rather than relying solely on gravity, allowing for rapid robot movement.…”

Research on mechanical optimization methods of cable-driven lower limb rehabilitation robot

“…Due to the evaluation of the CDPR's performances cannot be performed using the performance indexes for parallel robots with rigid links, an improved wrench exertion capability index was proposed to evaluate the maximum tension force that cable can exert along a direction of interest. The improved wrench exertion capability formulation can be used to analyze any cable parallel robots [30,31]. A kinematic optimization of the limb rehabilitation robot driven by pneumatic muscles was given by maximizing the mean value of the local transmission index subject to the lower and upper bounds of design variables based on the genetic algorithm [32].…”