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Title: Parallel elastic elements improve energy efficiency on the STEPPR bipedal walking robot

This study describes how parallel elastic elements can be used to reduce energy consumption in the electric motor driven, fully-actuated, STEPPR bipedal walking robot without compromising or significantly limiting locomotive behaviors. A physically motivated approach is used to illustrate how selectively-engaging springs for hip adduction and ankle flexion predict benefits for three different flat ground walking gaits: human walking, human-like robot walking and crouched robot walking. Based on locomotion data, springs are designed and substantial reductions in power consumption are demonstrated using a bench dynamometer. These lessons are then applied to STEPPR (Sandia Transmission-Efficient Prototype Promoting Research), a fully actuated bipedal robot designed to explore the impact of tailored joint mechanisms on walking efficiency. Featuring high-torque brushless DC motors, efficient low-ratio transmissions, and high fidelity torque control, STEPPR provides the ability to incorporate novel joint-level mechanisms without dramatically altering high level control. Unique parallel elastic designs are incorporated into STEPPR, and walking data shows that hip adduction and ankle flexion springs significantly reduce the required actuator energy at those joints for several gaits. These results suggest that parallel joint springs offer a promising means of supporting quasi-static joint torques due to body mass during walking, relieving motors of the needmore » to support these torques and substantially improving locomotive energy efficiency.« less
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  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Open Source Robotics Foundation, Mountain View, CA (United States)
  3. Florida Institute for Human and Machine Cognition (IHMC), Pensacola, FL (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1083-4435; 649351
Grant/Contract Number:
Accepted Manuscript
Journal Name:
IEEE/ASME Transactions on Mechatronics
Additional Journal Information:
Journal Name: IEEE/ASME Transactions on Mechatronics; Journal ID: ISSN 1083-4435
Research Org:
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
Country of Publication:
United States
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; 42 ENGINEERING legged locomotion; springs; torque; hysteresis motors; robot kinematics; hip