This article presents simulation and experimental results of an alternative scheme for reducing the consumption of compressed air in pneumatic positioning systems with external loads. The circuit adds a fast-switching on/off valve interconnecting the cylinder chambers on a typical system configuration comprising a symmetrical cylinder and a 5/3 directional proportional valve. The proportional valve is operated using a proportional–integral controller with dead zone compensation, and the auxiliary fast-switching on/off valve is controlled using a pulse-width modulation technique associated with another proportional–integral controller. An algorithm based on the pressure difference and the control signal for decision-making regarding compressed air saving is proposed. The results presented in this article show that the proposed scheme reduced the compressed air consumption by 47%–54%. The simulation results show that the presented approach can also be applied to circuits using asymmetrical cylinders with or without external loads.
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