Design and Nonlinear Control of a 2-DOF Flexible Parallel Humanoid Arm Joint Robot

Received May 11, 2017; Accepted Jul 10, 2017

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1. Introduction

Live working is a better option for executing related tasks of the electric system. In consideration of the fact that traditional live working is mainly accomplished by the labour, it is dangerous and easy to cause personal casualty accidents. In order to avoid the accident in the artificial live working, it has urgent realistic meaning and important research value that the robot replaces the labour to execute live working. The traditional live working robot [1] has some drawbacks such as low ratio of load to mass and high insulation cost mainly due to the serial mechanism of the robot arm with embedded electrical driving parts, respectively. It is suggested to develop a self-insulated robot arm without embedded electric parts. Inspired by human arm’s anatomical structure, the robot arm with cable-driven joints in parallel arrangement has already been studied [2]. According to the study, wrist/shoulder joint is the key module of the humanoid robot arm. Aiming at self-insulated requirement, the wrist/shoulder joint in [2] is simplified and redesigned as shown in Figure 1. The wrist/shoulder joint mechanism is in parallel arrangement with flexible spine and driven by three motors via three cables mimicking human muscles. Because of the existence of flexible parts in the mechanism which will cause vibration during motion control, it is necessary to study the problem of dynamics and vibration control for the wrist/shoulder joint. Figure 2 shows the developed robot prototype for the experimental study of the flexible wrist/shoulder joint mechanism in this paper.

[figure omitted; refer to PDF]

[figure omitted; refer to PDF]

Due to large workspace, high quality of load ratio, and small inertia, the cable-driven robot technology which stems from the crane system has become a research hot spot in the field of the robot [3, 4]. The cable-driven parallel robots include the cable-driven planar robots and the cable-driven space robots. However, the cable-driven...