Mechanism and Control of Continuous-State Coupled Elastic Actuation
Author(s)Huang, Tzu-Hao; Huang, Han-Pang; Kuan, Jiun-Yih
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Focusing on the physical interaction between people and machines within safety constraints in versatile situations, this paper proposes a new, efficient, coupled elastic actuation (CEA) to provide future human-machine systems with an intrinsically programmable stiffness capacity to shape the output force corresponding to the deviation between human motions and the set positions of the system. As a possible CEA system, a prototype of a two degrees of freedom (2-DOF) continuous-state coupled elastic actuator (CCEA) is designed to provide a compromise between performance and safety. Using a pair of antagonistic four-bar linkages, the inherent stiffness of the system can be adjusted dynamically. In addition, the optimal control in a simple various stiffness model is used to illustrate how to find the optimal stiffness and force trajectories. Using the optimal control results, the shortest distance control is proposed to control the stiffness and force trajectory of the CCEA. Compared to state-of-the-art variable stiffness actuators, the CCEA system is unique in that it can achieve near-zero mechanical stiffness efficiently and the shortest distance control provides an easy way to control various stiffness mechanisms. Finally, a CCEA exoskeleton is built for elbow rehabilitation. Simulations and experiments are conducted to show the desired properties of the proposed CCEA system and the performance of the shortest distance control.
DepartmentMassachusetts Institute of Technology. Department of Mechanical Engineering
Journal of Intelligent & Robotic Systems
Huang, Tzu-Hao, Han-Pang Huang, and Jiun-Yih Kuan. “Mechanism and Control of Continuous-State Coupled Elastic Actuation.” J Intell Robot Syst 74, no. 3–4 (September 22, 2013): 571–587.
Author's final manuscript