Title: Legged robot design and Van der Pol oscillator based control approach

Authors: Riadh Zaier; Omer Eldirdiry

Addresses: Mechanical and Industrial Engineering Department, College of Engineering, Sultan Qaboos University, Muscat 123, Sultanate of Oman ' Mechanical and Industrial Engineering Department, College of Engineering, Sultan Qaboos University, Muscat 123, Sultanate of Oman

Abstract: It is widely accepted within the field of animal locomotion that the gait is generated by a central pattern generator (CPG), which is usually modelled as a nonlinear oscillator. This paper proposes a mechanical design of a bio-inspired legged robot with a passive toe joint, and proposes a control method based on the key characteristics of the CPG generating the rolling motion of the gait. The overall control system is set as a Van der Pol oscillator, and the controller is then deduced accordingly. The legged robot is modelled as an inverted pendulum with a few control parameters that can be tuned to modulate the rolling motion and make it adaptive along with the stride. The locomotion controller is structured so that the overall closed loop system exhibits a stable limit cycle. Finally, the validation of the simulation platform and the implementation results of the designed robot is reported.

Keywords: biomechanical legs; Van der Pol oscillator; CPG; central pattern generator; limit cycle; nonlinear controller.

DOI: 10.1504/IJMIC.2021.123375

International Journal of Modelling, Identification and Control, 2021 Vol.38 No.3/4, pp.282 - 290

Received: 03 Aug 2020
Accepted: 06 Feb 2021
Published online: 13 Jun 2022 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article