Obstacle Avoidance of a Moving Sound Following Robot using Active Virtual Impedance

Abstract

An active virtual impedance algorithm is newly proposed to track a sound source and to avoid obstacles while a mobile robot is following the sound source. The tracking velocity of a mobile robot to the sound source is determined by virtual repulsive and attraction forces to avoid obstacles and to follow the sound source, respectively. Active virtual impedance is defined as a function of distances and relative velocities to the sound source and obstacles from the mobile robot, which is used to generate the tracking velocity of the mobile robot. Conventional virtual impedance methods have fixed coefficients for the relative distances and velocities. However, in this research the coefficients are dynamically adjusted to elaborate the obstacle avoidance performance in multiple obstacle environments. The relative distances and velocities are obtained using a microphone array consisting of three microphones in a row. The geometrical relationships of the microphones are utilized to estimate the relative position and orientation of the sound source against the mobile robot which carries the microphone array. Effectiveness of the proposed algorithm has been demonstrated by real experiments.

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

“…The active virtual impedance algorithm has been applied to dynamic obstacle avoidance for single and multiple obstacles [22]. Figure 13 shows the experimental environment of dynamic obstacle avoidance.…”

“…A new active virtual impedance algorithm is proposed to overcome the disadvantages of the conventional virtual impedance method [22] that generates attractive and repulsive forces proportional to the distance and relative velocities against the target and obstacle. Because the collision possibility increases abruptly when the obstacle approaches the mobile robot with a high relative velocity, a new nonlinear active virtual impedance has been proposed to incorporate the situations as follows ( 21 Figure 6 shows a K and a D as a function of the distance and relative velocity against the obstacle, which are in Equation (21).…”

“…In this study, the virtual impedance method has been adopted and elaborated to improve the obstacle avoidance performance [18]. The relationship between the uncertain environment and the mobile robot has been modeled as an impedance formed by the damper and spring, which generates a potential vector for the mobile robot [19][20][21][22]. The conventional virtual impedance algorithm may confront with a local minimum during navigation by the obstacles with fixed coefficients of the impedance.…”