An Active Virtual Impedance Control Algorithm for Collision Free Navigation of a Mobile a Robot

Abstract

An modified active virtual impedance control has been proposed for collision free navigation of a mobile robot to avoid front obstacles dynamically while a mobile robot is following a sound source. A mobile robot is controlled to follow a sound source with a velocity which is determined by virtual repulsive and attraction forces to avoid obstacles and to follow the sound source, respectively. To generate the virtual repulsive and attraction forces, a new modified virtual impedance is defined as a function of the distances and relative velocities to the sound source and obstacles from the mobile robot. In the conventional virtual impedance method, fixed coefficients have been used for the virtual impedance control. In this research, the coefficients are dynamically adjusted to elaborate the obstacle avoidance performance in various situations such as the multiple moving obstacles environment. A microphone array consisting of three microphones in a row has been attached on the mobile robot to detect the relative distance and velocity to the obstacles. The relative position and orientation of the sound source against the mobile robot has been estimated using the geometrical relationship of the microphones. As an application, the mobile robot can be used as a pet robot following the master with a sound source. The effectiveness of the proposed algorithm has been demonstrated through real experiments.