A Model-Based Biped Walking Controller Based on Divergent Component of Motion

Biped robots have high degrees of freedom and they are naturally unstable, hence design and develop a reliable walking controller is a complex subject which is one of the interesting topics in the robotic community. In this paper, we proposed a model-based walking controller which is able to negate the effect of external impacts not only by applying compensating torques but also by adjusting the landing location of swing leg. This controller is composed of two levels of control which takes into account the stable and unstable dynamics parts of center of mass (COM). In the proposed controller, the overall dynamics of a humanoid robot is approximated using an enhanced version of Linear Inverted Pendulum Plus Flywheel Model (ELIPPFM) and, according to this dynamics model, an optimal controller is designed to track the reference trajectories. Moreover, Divergent Component of Motion (DCM) is used to define when and where a robot should take a step to prevent falling. The proposed controller has been successfully tested by performing several simulations using MATLAB. The results showed that the proposed controller is capable of controlling the balance of a simulated robot in presence of severe disturbances.