Robotic assembly and trajectory planning using discrete event modelling

A new approach to process modeling, task synthesis, motion control and trajectory planning for robotic assembly is presented. Assembly is modeled as a discrete event dynamic system using Petri nets, incorporating both discrete and continuous aspects of the process. A process monitor based on recognizing contact state transitions, is presented. A discrete event controller is developed. The controller issues velocity commands that direct the system toward the next desired contact state, while maintaining currently desired contacts and avoiding unwanted transitions. A novel means of trajectory planning which incorporates the system´s ability to both monitor and control the process is given. Experimental results demonstrate highly successful insertion along the desired trajectory and the ability to detect, recognize and recover from errors and unwanted situations