Control of a micro positioning system using sensor fusion

The precision of micro assembly requires special tools in order to fulfill the high demands in accuracy and control of the assembly process. Our precise gripper tool with 2 DOF, the micro positioning system (MPS), enables micro assembly with standard industrial robots by compensating for vibrations and inaccuracies of the handling device. The developed control system combines data of three diverse sensors using signal level fusion with synchronized and dead time compensated sensor data to perform the corrective movement. The designed control system of the MPS consists of two closed-loop and one open-loop regulator. The sensor data is synchronized to the control sample rate with a linear first order extrapolation before fixing the data with a Kalman filter. The realized control system reduces vibrations to less than 30%, the position accuracy without disturbances is better than 2 microns according to experimental results. A comparison to a prior approach without sensor fusion shows the simplification of the control design reaching similar or even better results.