Ellipse-based leg-trajectory generation for galloping quadruped robots

Abstract

Controlling the motions of the front and rear legs and regulating the compliance of the legs are important for stable gallop. In this paper, a new method called ellipse-based trajectory generation method (ETGM) to generate foot trajectories for galloping quadrupeds is proposed. Unlike many previous works which attempted controlling foot trajectory, which need a sophisticated algorithm to avoid forcing the feet out of the workspace and thus making galloping unstable, a new trajectory generation method is based on an elliptic trajectory with constant radii but with changes in its center position. The rotational speed of the elliptic trajectory or the orbit trajectory is determined by the desired height of galloping and the running speed. It is assumed that each leg of a galloping quadruped robot has passive ankle joints with passive springs, thus acting as a spring loaded inverted pendulum (SLIP). To check the performance and effectiveness of the proposed method, a series of computer simulations of a 2-D quadruped robot galloping in the sagittal plane were performed. The simulation results show that the proposed method is simple to implement and very effective in generating stable gallop.

Optimization of Motion Planning and Control for Automatic Machines, Robots and Multibody Systems

“…The foot trajectory should not only meet the requirement of minimizing the contact force between the ground and the foot, but also ensure that the contact velocity of the foot is zero. Up to now, a variety of foot trajectory planning methods have been proposed, such as compound cycloid trajectory [34], modified compound cycloid trajectory [35,36], quintic polynomial curve trajectory [37], sine function trajectory [38], a combination trajectory of cubic polynomial and straight line trajectories [17] and elliptical trajectory [39]. However, the disturbance of the robot trunk is not considered in the above methods.…”

The Complex Dynamic Locomotive Control and Experimental Research of a Quadruped-Robot Based on the Robot Trunk

“…The foot trajectory should not only meet the requirement of minimizing the contact force between the ground and the foot, but also ensure that the contact velocity of the foot is zero. Up to now, a variety of foot trajectory planning methods have been proposed, such as compound cycloid trajectory [34], modified compound cycloid trajectory [35,36], quintic polynomial curve trajectory [37], sine function trajectory [38], a combination trajectory of cubic polynomial and straight line trajectories [17] and elliptical trajectory [39]. However, the disturbance of the robot trunk is not considered in the above methods.…”

Design for Several Hydraulic Parameters of a Quadruped Robot

“…The defect has been verified in experiments with physical robot. Kyeong Yong Kim and Jong Hyeon Park propose a new ellipse-based trajectory generation method for galloping quadruped robot [14]. The center of gravity of a quadruped robot will fluctuate greatly along forward and vertical directions while it runs using ellipse foot trajectory.…”