Position Control of Mobile Robots for Laser Material Processing

Laser Material Processing (LMP) has gained large attraction over the last years due to its high precision, accuracy and wide range of applications. The kinematic systems currently used in LMP are adapted from conventional manufacturing machines. These kinematic systems are usually built in accordance to the size of the structural element whereas mobile robots can be used to produce arbitrarily-sized structural elements. Thus, mobile robots are more flexible in many applications and so they are cheaper to build and have lower operating costs.This work investigates whether it is possible to build a controller for a four-mecanum-wheeled mobile robot so that it can be applied in laser material processing applications. A P, PI, PID and Lyapunov controllers are designed and tested on a real four-mecanum-wheeled mobile robot. All four controllers show reasonable trajectory tracking behavior, but none of the controllers reaches superior performance in comparison to the others, considering the different application test cases. Errors occur mainly due to external disturbances like uneven terrain. Finally, possibilities for improved tracking behavior are provided.