Nanometer-Scale Positioning Control with Compensator Using Standard Type Linear Pneumatic Actuator

抄録

In equipment manufacturing processes, pneumatic systems are commonly used because of their relatively simple design, high power-to-weight ratio, clean power source, safety, zero heat generation, and easy maintenance. Pneumatic systems contain devices such as linear actuators that convert air pressure and create straight-line motion and are widely used in industrial automation, robotics, and machinery. However, these pneumatic actuators are susceptible to frictional forces and difficult to control owing to their inherent air pressure characteristics. They therefore lack the precision and accuracy of electric actuators. Precision motion systems have become increasingly popular in manufacturing equipment, and this industrial revolution has led to the reduction of pneumatic systems adopted in precision motion systems. Many special type pneumatic servo systems have, through years of research and engineering efforts, been designed to meet special requirements such as precision and speed. However, these involve high investment and engineering time to adopt. Hence, this paper presents a novel compensator-based control system that uses a standard type linear pneumatic actuator to achieve ultra-high precision positioning control. The ultra-high-precision control feature, endowed with the inherent benefits of pneumatic systems such as safety, provides an all-around approach for future industrial automation. The research methodology involves the design of a control system with a novel compensator algorithm to address friction interference in pneumatic actuators, which is the primary causation factor of poor positioning accuracy in pneumatic servo systems. Moreover, the compensator can be easily integrated into any main control system, allowing easy adoption in any industrial field. The experimental results prove that high accuracy in the steady-state position can be achieved by this proposed algorithm. A steady-state accuracy of ±1 nm was obtained. Compared to previous studies in which accuracies of approximately 5 nm were obtained, the compensator-based control system achieves a considerably higher accuracy than the previously reported accuracies, matching that of electric actuators. The final section of this paper will present potential directions for future work.