101. Pneumatic Variable Series Elastic Actuator
- Author
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Molei Wu, Xiangrong Shen, and Hao Zheng
- Subjects
0209 industrial biotechnology ,Engineering ,Plant ,02 engineering and technology ,Computer Science::Robotics ,03 medical and health sciences ,020901 industrial engineering & automation ,0302 clinical medicine ,Motor controller ,Control theory ,medicine ,Instrumentation ,Equilibrium point ,Pneumatic actuator ,business.industry ,Pressure control ,Mechanical Engineering ,Motor control ,Stiffness ,Control engineering ,Research Papers ,Computer Science Applications ,Control and Systems Engineering ,medicine.symptom ,business ,Actuator ,030217 neurology & neurosurgery ,Information Systems - Abstract
Inspired by human motor control theory, stiffness control is highly effective in manipulation and human-interactive tasks. The implementation of stiffness control in robotic systems, however, has largely been limited to closed-loop control, and suffers from multiple issues such as limited frequency range, potential instability, and lack of contribution to energy efficiency. Variable-stiffness actuator represents a better solution, but the current designs are complex, heavy, and bulky. The approach in this paper seeks to address these issues by using pneumatic actuator as a variable series elastic actuator (VSEA), leveraging the compressibility of the working fluid. In this work, a pneumatic actuator is modeled as an elastic element with controllable stiffness and equilibrium point, both of which are functions of air masses in the two chambers. As such, for the implementation of stiffness control in a robotic system, the desired stiffness/equilibrium point can be converted to the desired chamber air masses, and a predictive pressure control approach is developed to control the timing of valve switching to obtain the desired air mass while minimizing control action. Experimental results showed that the new approach in this paper requires less expensive hardware (on–off valve instead of proportional valve), causes less control action in implementation, and provides good control performance by leveraging the inherent dynamics of the actuator.
- Published
- 2016