Inverse kinematic for an 8 degrees of freedom biped robot based on cubic polynomial trajectory generation

Humanoid walking trajectory is a complicated task due to a large number of degrees of freedom (DOFs) and varies in mechanical structure during walking. This paper first introduces a newly designed mechanism, an 8 DOF biped robot, which designed in SolidWorks. Then it presents a human like walking trajectories for the feet and the hips in order to achieve smooth and continuous walking trajectory. For reaching this goal, we applied cubic and Hermit spline polynomial interpolation of initial conditions for the robot position, velocity and acceleration. We specify the bipedal walking sequences and define some important issues in order to obtain a continuous swing leg trajectory. Finally, an inverse kinematic is implemented to convert the trajectories into joints rotation. Geometric approach for inverse kinematic is applied and expressed in terms of joins angles, and the walking gait is generated based on the joints angles. The effects of the trajectory are illustrated by simulation results.