Energy efficient optimal control of pneumatic actuator systems.
Pneumatic actuators, compared to their counterparts, have distinct advantages, for example, cleanness in the environment, rapid point-to-point positioning, high load-carrying capacity-to-size ratio, mechanical simplicity, low cost and ease of maintenance. However, the energy efficiency of pneumatic actuator systems is low. So, improvement of energy efficiency is of foremost importance. The objective of the paper is to investigate the possibility of improving servo-pneumatic system energy efficiency through re-designing velocity profiles. The work described in the paper was initially motivated by some new findings from simulation studies. When the target position is fixed, the compressed air consumption can be different if the movement of pneumatic piston follows different velocity profiles or travels in different trajectories. Three particular shaped profiles have been studied. These are trapezoidal, parabolic and sinusoidal shaped profiles. Simulation results show that the system with sinusoidal profiles uses the least compressed air, and the one with parabolic profiles uses the most compressed air. The outcomes of simulation studies indicate that the energy efficiency of pneumatic systems can be improved when the velocity profiles are properly designed. Following the simulation studies, a theoretical analysis based on optimal control theory is carried out.
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