Soft Landing and Disturbance Rejection for Pneumatic Drives with Partial Position Information*

Pneumatic drives are used in a wide range of industrial applications. Most of the pneumatic drive applications are simple point-to-point movements, where the motion characteristics is typically set up once by manual tuning. Changes in the operating conditions demand a new manual adjustment and thus additional costs. This work aims at developing a conrol strategy for pneumatic drives to save manual tuning effort and to minimuze the overall system costs. For this cheap position sensors that operate only near the end stops in combination with energy efficient switching valves are used to ensure a smooth movement of the drive and soft landing at the end stops. To pass through the region with no position information, a two-degrees-of-freedom control strategy is employed to account for model uncertainties and disturbances. Inside the position measurement region, compliance control ensures soft landing. The presented strategy is validated by a series of measurements on an experimental test bench.