Leg Thrust Control for Stabilization of Dynamic Gaits in a Quadruped Robot

Abstract

Several parameters must be regulated to control and stabilize running robots: for example, the regulation of the leg touchdown angles and the hip torques has been successfully used in the past to control quadruped machines. However, the regulation of leg thrust can also be an effective technique for controlling the characteristics of the gait (apex height, forward speed, attitude rate) and it can play an important role in gait stabilization. This paper presents the mechanical systems, the models and control strategies employed to regulate leg thrust on the KOLT quadruped robot. Two thrust control methods are proposed and tested experimentally. The closed loop method regulates thrust through the control of the hip liftoff speed, a conceptually simple control strategy that has the property of stabilizing pronk gaits without the need of central feedback. An open loop control method to regulate the energy added in each hop is also presented. Both experiments with the KOLT robot and simulations show the efficacy of the proposed approaches.

The authors would like to thank Paul Csonka and Surya P. N. Singh for their assistance in this work. The authors also acknowledge the support of the National Science Foundation, Grant No. IIS-0208664 and the Secretaria de Estado de Universidades of the Spanish Ministry of Education and Science.