Continuous Sliding Mode Control of a Pneumatic Actuator

Sliding mode control has been promoted as a means to overcome the nonlinearities associated with pneumatic positioning systems. Previously published performance results have been disappointing with reported accuracies of only ±5 mm and poor tracking of the sliding surface. New experimental results demonstrate that a properly designed continuous sliding mode controller (CSLM) is capable of accuracies of better than ±0.2 mm. Further, the CSLM controller is able to maintain performance when the load mass is varied by upwards of a factor of 10. Direct comparison to a conventional pro-portional differential pressure controller provides evidence that CSLM is indeed more robust than comparable controllers for this application.