Modelling, estimation and control concepts for pneumatic systems

Pressurized gases are widely used as energy sources in various fields of applications. In the two parts of this work, two typical tasks for different industrial fields are investigated. The first task concerns the automotive industry, which is faced with the challenge to meet stricter exhaust emission standards and thus to reduce fuel consumption. To this end, a number of different concepts have been presented in the past. One, which is already in use for heavy duty vehicles, is the hydraulic hybrid drive. In this approach, a gas charged hydraulic accumulator is utilized as energy storage. This so-called hydropneumatic accumulator is a key element for the hybrid drive. For the control of hybrid drives, the actual amount of energy stored in the accumulator, also referred to as state of charge, is an indispensable information, but cannot be easily measured. Therefore, two tailored model based estimation strategies are developed. The second part deals with pneumatic linear drives, with pressurized air as the power source. The increasing demand for flexible and robust low-cost solutions, requires new approaches for the motion control task of pneumatic drives. To this end, highly flexible, but cost-efficient solutions for point-to-point motions of pneumatic cylinders, which are one of the most common applications in pneumatics are developed. The main challenges in this application are varying working conditions (e. g. supply pressure level, moving mass, friction) over the lifetime of the drive. The presented solution consists of a sensor and actuator concept, where the position is only measurable near the two stroke-ends of the cylinder. To ensure robust piston movements even without full-stroke position information, a tailored control and estimation concept is developed.