Self-tuning control of a low-friction pneumatic actuator under the influence of gravity

Traditionally the positioning of pneumatic actuators has been limited to mo vement between preset stops or switches. The restricting factors preventing the use of pneumatic cylinders for accurate servo-control arise from highl y nonlinear dynamic properties such as air compressibility and friction eff ects, which combine to severely degrade time response and positional accura cy. Many real systems are influenced by external gravity forces, which comp ound the problem of position control. A self-tuning system incorporating an external force balancing term is proposed using a low-friction cylinder, T he low-friction cylinder is compared to conventional, sealed cylinders to d emonstrate the increased performanc.