Design of Adjustable Gravity-Balancing Mechanisms Based on Torque Matching

• Main Authors: Zong-WeiYang, 楊宗偉
• Other Authors: Chao-Chieh Lan
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/98221249462756204189

碩士 === 國立成功大學 === 機械工程學系 === 103 === Compensating the payload weight of a robotic manipulator requires a mechanism that can generate a nonlinear torque curve. Existing gravity-balancing mechanisms (GBMs) rely on linear springs with various principles to generate the required torque profile. To be used as an exoskeleton for supporting a human limb with strength deficiency, a GBM needs to be compact and provide friendly motion. This paper presents the design of a novel GBM that is suitable for shoulder exoskeleton. The idea is to employ two linear springs to synthesize the required nonlinear torque curve. The springs are concentrated on the base joint to avoid possible interference with human motion. An optimization formulation is given to maximize the weight compensation capability. The effects of various parameters on the achievable weight are discussed. The linear springs are specifically designed to generate large stiffness in a limited space. The effects of various parameters on the achievable size are discussed. Low-volume compliant springs are specifically designed to serve as the linear springs so that large stiffness can be generated in a limited space. Through preloading the springs, the GBM can easily adjust its torque curve to match different weights. An illustrative prototype is given with experiment verifications to demonstrate the claimed merits of the proposed GBM.