Artificial potentials with elliptical isopotential contours for obstacle avoidance

Previous use of artificial potentials has demonstrated the need for an obstacle avoidance potential that closely models the obstacle, yet does not generate local minima in the workspace of the manipulator. However, none of the artificial potential functions proposed to date satisfy this criterion. In this paper we present a new obstacle avoidance potential, based on modified ellipses, that prevents the formation of local minima when added to spherically symmetric attractive wells. A modified form of this elliptical potential provides safe approach towards objects. We have implemented our potentials in a simulation and the results exhibit an improvement over existing potential schemes. The simulation also employs an algorithm that eliminates collisions with obstacles by calculating the repulsive forces exerted on links, based on the shortest distance to an object.