1. A Fixed Structure Gain Selection Strategy for High Impedance Series Elastic Actuator Behavior
- Author
-
Luis Sentis, Kenan Isik, and Gray C. Thomas
- Subjects
0209 industrial biotechnology ,Series (mathematics) ,Computer science ,Mechanical Engineering ,020208 electrical & electronic engineering ,Selection strategy ,Structure (category theory) ,Stiffness ,02 engineering and technology ,Transfer function ,Computer Science Applications ,High impedance ,020901 industrial engineering & automation ,Control and Systems Engineering ,Control theory ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,medicine.symptom ,Actuator ,Instrumentation ,Position control ,Information Systems - Abstract
Series elastic actuators (SEA) are widely used for impact protection and compliant behavior, but they typically fall short in tasks calling for accurate position control. In this paper, we propose a simple and effective heuristic for tuning series elastic actuator controllers to a high impedance position control behavior, which compares favorably with previous publications. Our approach considers two models, an ideal model and a nonideal model with time delays and filtering lag. The ideal model is used to design cascaded proportional-derivative (PD)-type outer impedance and inner force loops as a function of critically damped closed-loop poles for the force and impedance loops. The nonideal model provides an estimate of the phase margin of the position controller for each candidate controller design. A simple optimization algorithm finds the best high-impedance behavior for which the nonideal model meets a desired phase margin requirement. In this way, the approach automates the trade-off between force and impedance bandwidth. The effect of important system parameters on the impedance bandwidth is also analyzed and the proposed method verified with a physical actuator.
- Published
- 2018