Extended Capture Point and Optimization-based Control for Quadrupedal Robot Walking on Dynamic Rigid Surfaces⁎⁎Research by A. Iqbal and Y. Gu was supported in part by NSF under Grant no. CMMI-1934280. Corresponding author: Y. Gu

• Published in: IFAC-PapersOnLine Vol. 54; no. 20; pp. 72 - 77
• Main Authors: Iqbal, Amir, Gu, Yan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2021
• Subjects: Dynamic Modeling; Legged Locomotion; Motion Control Systems; Motion Planning; Quadratic Programming; Legged Locomotion; Motion Planning; Quadratic Programming; Motion Control Systems; Dynamic Modeling
• ISSN: 2405-8963
• DOI: 10.1016/j.ifacol.2021.11.155

Stabilizing legged robot locomotion on a dynamic rigid surface (DRS) (i.e., rigid surface that moves in the inertial frame) is a complex planning and control problem. The complexity arises due to the hybrid nonlinear walking dynamics subject to explicitly time-varying holonomic constraints caused by the surface movement. The first main contribution of this study is the extension of the capture point from walking on a static surface to locomotion on a DRS as well as the use of the resulting capture point for online motion planning. The second main contribution is a quadratic-programming (QP) based feedback controller design that explicitly considers the DRS movement. The stability and robustness of the proposed control approach are validated through simulations of a quadrupedal robot walking on a DRS with a rocking motion. The simulation results also demonstrate the improved walking performance compared with our previous approach based on offline planning and input-output linearizing control that does not explicitly guarantee the feasibility of ground contact constraints.