Online collision avoidance for industrial robots with six degrees of freedom

An online collision avoidance strategy is presented for two industrial robots sharing a common workspace. The algorithm can be computed very fast to provide secure trajectories within the cycle time of industrial robot controllers. Substitution of the complex kinematics of any industrial robot with six degrees of freedom by the more convenient kinematics of the reduced actual robot (RAR) and computation of a virtual hinderance robot (VHR), which describes the most dangerous joint angle position of the RAR with regard to another RAR in the workcell leads to a degree of danger in each component of the RAR´s cylindrical frame and results in the evaluation of a secure trajectory. An online decision is made between each component of the preplanned trajectory and the corresponding component of the secure trajectory. The collision-free trajectory is transformed back to the 6D-workspace of the industrial robot. The efficiency of the authors´ strategy is illustrated in an example with two PUMA 562 robots