Control and estimation strategies for pneumatic drives with partial position information

Flexibility in production demands for flexible components which automatically adjust to new operating conditions. Pneumatic drives are often used in various industrial applications, e.g., for point-to-point movements. The motion characteristics is typically set up by manual tuning. Therefore, changes in the production lines typically require costly manual readjustments. This can be avoided by using a robust, but expensive servo-control with pressure sensors and a full-stroke position sensor. In this paper, we propose a cost-efficient and flexible alternative by combining classical pressure sensors with cheap partial position sensors at the stroke ends to estimate the parameters of the mechanical system of the drive. This allows to readjust the motion characteristics in real time. Another costly issue is the limitation of the lifetime of the drive, when varying loads lead to large impacts at the stroke ends. To increase the lifetime, a novel non-overshooting trajectory planning algorithm is presented in this work. The overall control concept is implemented on two lab test benches and the experimental results prove its excellent performance and robustness with respect to changing operating conditions.