Design of dynamically balanced gait for the biped robot while crossing the obstacle

Abstract

The primary objective of this research work is to generate a dynamically balanced gait for the 16-DOF biped robot while crossing an obstacle using the concept of the zero moment point (ZMP). Also, the authors discussed both the theoretical justification and its practical feasibility on real biped robot. Initially, the position and orientation of the biped robot were obtained with the help of forward kinematics while crossing the obstacle. Later on, various joint angles of the biped robot were calculated using the inverse kinematics approach. Further, the Lagrange-Euler formulation approach was employed for evaluating the dynamics of the biped robot. To generate the smooth gait of the biped robot, a cubic polynomial equation has been assigned for foot and wrist trajectories in the sagittal plane and hip trajectories in the horizontal plane. This integration allows the robot to cross the obstacles while maintaining dynamic balance, marking a significant advancement while crossing the obstacle with a height and width equal to 50 mm, which is 16.10% of the length of the robot’s leg. While crossing the obstacle, the gait of the biped robot has been considered in three stages, such as landing the foot on the obstacle, landing the foot on the ground away from the obstacle by one leg and crossing over the obstacle by another leg. A simulation study has been conducted on MATLAB to verify the dynamically balanced gait while crossing the obstacle. Finally, the generated gait angles are fed into the real 16-DOF biped robot developed by the Robotics Lab at MANIT Bhopal. It has been observed that the generated gait at three stages is more dynamically balanced while crossing the obstacle.