Towards On-Line Trajectory Computation

This paper proposes a new way of trajectory generation for industrial manipulators. A real-time algorithm for the interpolation of synchronized and time-optimal manipulator trajectories with arbitrary input values is presented. The method has been developed and implemented for multi-sensor systems, where sensor events can abruptly change desired target positions and trajectory constraints from one control cycle to another (i.e. maximum velocities, accelerations, and jerks). This work mainly presents a simple on-line second-order-trajectory generator and gives an outlook to a third-order-trajectory generator. Both algorithms generate time-optimal position progressions and require computational three steps: A. determination of the degree of freedom that requires the longest execution time, B. synchronization of all degrees of freedom by adapting maximum velocities and accelerations, C. calculation of new output values (position, velocity, and acceleration). Experimental results as well as a description of how to integrate this approach into manipulation control architectures are presented