8-DoF Biped Robot with Compliant Links

This paper proposes a new design of a 8-degrees of freedom (DoF) biped robot with compliant shanks and its optimum walking trajectory generation. The shanks of a biped are replaced by compliant links made of Aluminium sheets. Compliant links are modeled using finite element method (FEM). Continuous gait trajectory is generated for walking in a straight path on a horizontal plane by defining the hip and swing foot ankle trajectories with respect to the stance-leg ankle joint. The dynamic equations of motion of the bipeds are derived using Euler-Lagrangian method to calculate the work done in a single step for both rigid and compliant bipeds. For balancing the biped dynamically during walking, zero-moment point (ZMP) method is used. Varying gait parameters (step length and hip height), various gait trajectories are simulated. Genetic algorithm (GA) is used to find the optimal walking trajectory based on lower work done and higher stability. Experiments were carried out in which a biped robot with compliant links was made to follow the simulated optimal trajectories.