Dynamic Stabilization of NAO Humanoid Robot Based on Whole-Body Control with Simulated Annealing

The prime challenge in a humanoid robot is its stability on two feet due to the presence of an underactuated system. In this paper, the complete dynamics of the humanoid robot has been described in essence of torque calculation at the end effectors. Presence of various restraints in humanoid robot motion makes the task of stabilization an even humongous one. Therefore, to neutralize these constraints, whole-body control (WBC) has been proposed to consider the free-floating base and to ensure the stability of the humanoid robot. Dynamic modeling of the humanoid robot is performed based on the Langrage-Euler formalism to obtain the maximum torque at the joints. This approach is utilized to formulate the torque equation and solve the problem of stabilization. WBC deals with the limitation of attainment of well nimble dynamics behavior operated at high speeds. The simulated annealing approach is preferred to tune WBC to get efficient stabilization and eliminate the earlier limitation. In addition, the zero-moment point (ZMP) criterion is taken care of as it affects the stability of the humanoid robot aggressively. Simulations on V-REP are carried out to understand the torque behavior at each joint. To validate the simulation results, the experiments are carried out on the NAO humanoid robot in real experimental conditions. The experimental and simulation results are compared through torque versus time graphs, and they both show good agreement with deviation under 4% between them. The proposed technique is then compared with various previously implemented techniques which confirm the robustness and efficiency of the proposed methodology.