Task-level adaptation using a discrete event controller for robotic assembly

A task-level adaptive controller is presented for the discrete event control of robotic assembly tasks. Using a Petri net model of the assembly task, velocity constraints are derived from which desired velocity commands are obtained. Due to modeling errors and uncertainties, the velocity commands may result in a suboptimal, unwanted contacts between the workpiece and the environment. Simple vector addition is used to adapt the velocity commands so as to avoid the unwanted contacts. Gram-Schmidt orthogonalization is used to ensure that the adaptation does not violate any geometric constraints. An example is given with experimental results, demonstrating the viability and success of the adaptation method