An efficient leg with series–parallel and biarticular compliant actuation: design optimization, modeling, and control of the eLeg

Abstract

We present the development, modeling, and control of a three-degree-of-freedom compliantly actuated leg called the eLeg, which employs both series- and parallel-elastic actuation as well as a bio-inspired biarticular tendon. The leg can be reconfigured to use three distinct actuation configurations, to directly compare with a state-of-the-art series-elastic actuation scheme. Critical actuation design parameters are derived through optimization. A rigorous modeling approach is presented using the concept of power flows, which are also used to demonstrate the ability to transfer mechanical power between ankle and knee joints using the biarticular tendon. The design principles and control strategies were verified both in simulation and experiment. Notably, the experimental data demonstrate significant improvements of 65–75% in electrical energy consumption compared with a state-of-the-art series-elastic actuator configuration.

Editorial: Soft Robotic Modeling and Control: Bringing Together Articulated Soft Robots and Soft-Bodied Robots

“…Roozing et al analyze a compliantly actuated 3DOF leg with bio-inspired tendons through simulation and evaluate it via an experiment. The energy consumption is reduced significantly compared with state-of-the art series-elastic actuator configurations.…”

Hybrid Parallel Compliance Allows Robots to Operate With Sensorimotor Delays and Low Control Frequencies

“…Series elastic actuation (SEA) can simplify control, improve robustness and interaction safety, and protect actuators from overloads ( Raibert et al, 1984 ; Robinson et al, 1999 ; Pratt and Krupp, 2004 ; Hutter et al, 2011 ; Calanca et al, 2015 ; Hutter et al, 2016 ; AhmadSharbafi et al, 2020 ). Designs with parallel mounted springs and actuators (parallel elastic actuation, PEA) can increase leg forces, improve locomotion energy efficiency, and reduce actuator loading ( Gunther et al, 2015 ; Niehues et al, 2015 ; Plooij et al, 2016 ; Yesilevskiy et al, 2016 ; Liu et al, 2018 ; Toxiri et al, 2018 ; Yesilevskiy et al, 2018 ; Roozing et al, 2019 ; Ambrose and Ames, 2020 ). Combined parallel and serial elastic designs have been proposed, leading to reduced peak torques and improved locomotion applicability ( Grimmer et al, 2012 ).…”

Singularity Loci, Bifurcated Evolution Routes, and Configuration Transitions of Reconfigurable Legged Mobile Lander From Adjusting, Landing, to Roving

“…Recent advances in the interdisciplinary fields of planetary exploration [1][2][3][4][5], reconfigurable mechanism [6][7][8][9][10], and autonomous robot [11][12][13][14][15] indicate that the multifunctional and robotic detection probe will become one of the development trends. To survive in the unknown even hostile extraterrestrial environment, the complex task requirements are rendered with the hopes of merging functions of adjusting and landing, and roving and operating into a versatile counterpart-the reconfigurable legged mobile lander (ReLML).…”