Computational Efficient Balance Control for a Lightweight Biped Robot with Sensor Based ZMP Estimation

This paper presents a computational efficient balance control algorithm developed for a lightweight biped. A LIP model of the robot is combined with the ZMP calculation to derive a joint space control action based on a PD controller. Furthermore, a method is implemented to estimate the ZMP directly from the center of pressure measured using the force sensors installed under the feet of the robot. This, allows a real time implementation of the controller without using the robot direct kinematics, reducing model inaccuracies and improving the controller reactivity. Simulation results and tests on the real robot prototype shows that the control system is able to compensate for external disturbances forces up to 10N reducing the oscillations of 60%.