Saving Energy by Predictive Supply Air Shutoff for Pneumatic Drives

Pneumatic drives are a widespread drive technology with generally large energy saving potentials. Besides a proper sizing of the drive, an optimized operation can reduce energy intake of a pneumatic drive strongly. In this paper, we consider the optimal control of a pneumatic cylinder actuated by a switching valve. We present an offline computed feed-forward control solution and an online control strategy. The offline control strategy delivers the energy optimal control of the cylinder. To enhance the robustness and to reduce the necessary implementation effort, we then present a novel online control strategy, employing a model-based online prediction of the system behavior. The two control concepts are analyzed and compared in simulation and experiment, where our experimental results reveal a reduction of the compressed air intake by about one half compared to a standard switching control strategy.