Iterative learning control applied to a gantry robot and conveyor system

Synchronization is routinely required to coordinate the actions of the various sub-systems involved in process applications. This is commonly achieved through direct mechanical coupling, involving gears, drive belts and cams. Apart from the additional cost incurred, these components are subject to wear, constrain the layout of the plant and may have limited accuracy. It is shown in this paper that a mechanical linkage between two sub-systems may be replaced by instead implementing a control scheme comprising an iterative learning controller together with a supervisory control loop. To illustrate the approach, two types of iterative learning controller are first implemented on a gantry robot test facility to confirm the high levels of tracking accuracy that may be achieved. The supervisory control loop is then added to synchronize the ‘pick and place’ action of the robot with a conveyor system moving at constant velocity. Experimental results are provided to confirm both the accurate tracking performance produced by the iterative learning controller, and the high level of synchronization achieved by the overall scheme.