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Optimal elastic coupling in form of one mechanical spring to improve energy efficiency of walking bipedal robots

Bauer, Fabian 1; Römer, Ulrich ORCID iD icon 1; Fidlin, Alexander 1; Seemann, Wolfgang 1
1 Institut für Technische Mechanik (ITM), Karlsruher Institut für Technologie (KIT)


This paper presents a method to optimize the energy efficiency of walking bipedal robots by more than 80% in a speed range from 0.3 to 2.3 m/s using elastic couplings – mechanical springs with movement speed independent parameters. The considered planar robot consists of a trunk, two two-segmented legs, two actuators in the hip joints, two actuators in the knee joints and an elastic coupling between the shanks. It is modeled as underactuated system to make use of its natural dynamics and feedback controlled via input-output linearization. A numerical optimization of the joint angle trajectories as well as the elastic couplings is performed to minimize the average energy expenditure over the whole speed range. The elastic couplings increase the swing leg motion’s natural frequency thus making smaller steps more efficient which reduce the impact loss at the touchdown of the swing leg. The process of energy turnover is investigated in detail for the robot with and without elastic coupling between the shanks. Furthermore, the influences of the elastic couplings’ topology and of joint friction are analyzed. It is shown that the optimization of the robot’s motion and elastic coupling towards energy efficiency leads to a slightly slower convergence rate of the controller, yet no loss of stability but a lower sensitivity with respect to disturbances. ... mehr

Postprint §
DOI: 10.5445/IR/1000062327
Veröffentlicht am 18.05.2018
DOI: 10.1007/s11044-016-9509-8
Zitationen: 3
Zitationen: 4
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Technische Mechanik (ITM)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2016
Sprache Englisch
Identifikator ISSN: 1384-5640, 1573-272X
KITopen-ID: 1000062327
Erschienen in Multibody system dynamics
Verlag Springer
Band 38
Heft 3
Seiten 227–262
Schlagwörter bipedal robot, dynamic walking, nonlinear feedback control, optimization, energy efficiency, elastic coupling
Nachgewiesen in Web of Science
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