A Stable Walking Strategy of Quadruped Robot Based on Foot Trajectory Planning

For a quadruped robot to implement steady moving on horizontal planes, avoiding the impact against the ground, a foot trajectory planning method underling low contact impact was presented. At first, kinematic model of the quadruped robot though D-H algorithm have been established. Then, the foot trajectories, which are continuous not only in displacements and velocities but also in accelerations, was scheduled based on the walking gait. Lastly, the steering and straight line movements of the robot were simulated, simulation experiments show that the quadruped robot motion stably on horizontal planes without impact and sliding.

I. Introduction

As an integral part of the mobile robot, legged robot is gradually becoming the hotspot. With its discontinuous support motion and good performance in capacity, mobility and versatility, quadruped robot, such as BigDog [1] and HyQ [2] has great potential for applications in a complex environment. According to the nature of the stability, the gait of quadruped robots are classified into static gaits and dynamical gaits. Static gaits focuses on stability, whereas dynamical gaits focuses on fast and efficient [3]. Recently, a large number of control method, such as floating-base inverse dynamics control and predictive force control introduced in [4], have been proposed to control quadruped robots walking over non-perceived obstacles and rocky terrain. For steady moving on horizontal planes, the idea of planning smooth trajectories for robot motion has been proposed by several researchers [5]–[7]. The trajectory of quadruped robot like Cubic Trajectory, Cubic mixed with the linear Trajectory, Sinusoidal Trajectory and quintic polynomial Trajectory has been widely used. In this paper, quintic polynomial mixed with the linear interpolation algorithm based on static gaits were presented to make the robot do steering and straight line motion.