Quadruped Robot Foot-end Trajectory Generation Algorithm

Abstract

In the movement of a quadruped robot, gait is an important feature, and the planning and control of gait cannot be separated from the planning of foot-end trajectory. A bionic impact-free foot-end trajectory for a quadruped robot is proposed in this study by combining the foot-end workspace and joint space. First, the trajectory of the foot-end of the swing phase is planned in three sections: back swing, stride, and forward swing. The back and forward swings adopt quintic polynomial curves, and the stride adopts a cycloid curve. Then, the planned foot-end trajectory is interpolated in equal-time intervals, and the obtained interpolated values are converted to joint interpolation by inverse kinematics. Finally, the angular velocity and angular acceleration at the joint interpolation are estimated by the difference quotient estimation method, and the joint space trajectory is planned using a quintic polynomial. The simulation experiments show the smooth curves of the foot trajectory and joint trajectory obtained by the algorithm planning, and the initial and final velocity and acceleration are zero. Meanwhile, the velocity and acceleration changes of the trajectory are continuous without sudden changes. After interpolation, the foot-end trajectory is restored completely while reducing the calculation.