Self-folding gravity compensation mechanism for a supplementary folding robot arm: Design, analysis and implementation

Abstract

This paper presents a self-folding gravity compensation mechanism (SF-GCM) for supplementary folding robot arms to assist the worker. The foldable mechanism of SF-GCM consists of multiple links, torsional springs, pulleys, and cables to counter the moment due to the arm's weight and payload. The SF-GCM mechanism can fold and unfold according to the arm length and remotely provide a significant gravity compensation force. The design parameters of the robot arm are formulated, and a model of the equivalent stiffness model is proposed and analyzed. Analyzing the model was helpful to calculate the approximate stiffness values for designing the customized self-folding gravity compensation mechanism for foldable robots. A prototype of the SF-GCM mechanism was developed and its performance was evaluated experimentally for the payloads of 0.1 kg and 0.5 kg. It turns out that SF-GCM could compensate for the end-effector payload during arm extension and contraction.