This paper presents the development of a compact, modular rotary series elastic actuator (SEA) design that can be customized to meet the requirements of a wide range of applications. The concept incorporates flat brushless motors and planetary gearheads instead of expensive harmonic drives and a flat torsional spring design to create a lightweight, low-volume, easily reconfigurable, and relatively high-performance modular SEA for use in active impedance controlled devices. The key innovations include a Hall effect sensor for direct spring displacement measurements that mitigate the negative impact of backlash on SEA control performance. Both torque and impedance controllers are developed and evaluated using a 1-degree-of-freedom (DoF) prototype of the proposed actuator package. The results demonstrate the performance of a stable first-order impedance controller tested over a range of target impedances. Finally, the flexibility of the modular SEA is demonstrated by configuring it for use in five different actuator specifications designed for use in the uBot-7 mobile manipulator requiring spring stiffnesses from 3 N · m/deg to 11.25 N · m/deg and peak torque outputs from 12 N · m to 45 N · m.
A Compact, Modular Series Elastic Actuator
Manuscript received June 12, 2015; final manuscript received March 6, 2016; published online April 1, 2016. Assoc. Editor: Jun Ueda.
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Cummings, J. P., Ruiken, D., Wilkinson, E. L., Lanighan, M. W., Grupen, R. A., and Sup, F. C., IV (April 1, 2016). "A Compact, Modular Series Elastic Actuator." ASME. J. Mechanisms Robotics. August 2016; 8(4): 041016. https://doi.org/10.1115/1.4032975
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