Energy Saving in Pneumatic Servo Control Utilizing Interchamber Cross-Flow

This paper proposes a structure and control approach for the energy saving servo control of a pneumatic servo system. The energy saving approach is enabled by supplementing a standard four-way spool valve controlled pneumatic actuator with an additional two-way valve that enables flow between the cylinder chambers. The “crossflow” valve enables recirculation of pressurized air, and thus enables the extraction of stored energy that would otherwise be exhausted to the atmosphere. A control approach is formulated that supplements, to the extent possible, the mass flow required by a sliding mode controller with the recirculated mass flow provided by the crossflow valve. Following the control formulation, experimental results are presented that indicate energy savings of 25–52%, with essentially no compromise in tracking performance relative to the standard sliding mode control approach (i.e., relative to control via a standard four-way spool valve, without the supplemental flow provided by the crossflow valve).