Non-rail mobile rack which is used as a cargo storage in logistics center can improve the storage capacities. Furthermore, It has an advantage to apply in traditional logistic center without change any renovation such as installing rail.
However when it is operated by a separated drive actuators which is mounted on the left and the right wheels, a precise position control for the wheels would be necessary even if unbalanced cargo weight on the non-rail mobile rack would be effected to the control.
Therefore, in this study, there is necessary to internal synchronize control for position tracking between left and right wheels on the non-rail mobile rack. Also an external synchronize control for same straight movements between mobiles would be necessary.
For developing the internal and the external synchronize control algorithm, we suggest a synchronize control algorithm based on the repetitive control theory. Specially, an internal synchronize control algorithm with repetitive control theory use the robust servo control method due to parameter variations. In this case, we can set up the gains for robust servo control system by considering the cargo variations on the mobile rack. Also, for constructing the external synchronize control algorithm, we use a double repetitive control system to perform synchronize control between each mobile rack.
Finally, the efficiency of proposed control algorithm will be verified by simulation and experimental results. And the proposed algorithm would be applied to industrial area easily.