A Novel Pneumatic Stepper Actuator Using Constant Air Pressure

Abstract

The application of constant air pressure to control a stepper actuator is introduced in this study. This actuator consists of a piston that reciprocates inside a cylinder. At the end of each stroke, the piston strikes the end of the cylinder and changes the position of the inlet and outlet valves. Each impact at the end of the cylinder causes the cylinder to move one step forward. By semi-closing the outlet valves at one end, the magnitude of the impulsive force acting on each end of the cylinder can be adjusted once before driving the actuator, and their status is not changed during the actuation. The impact force is adjusted to be greater than the friction force, causing the actuator to move in one direction. A fluid–structure interaction analysis was performed using the finite element method to evaluate the feasibility of the proposed design and to conduct an initial evaluation of the required parameters. The impulsive force can be adjusted by inputting constant air pressure. For this purpose, the experiment was conducted in two different modes. In the first case, the actuator was placed horizontally without an angle, and the finest resolution of movement was 1 µm. In the second experiment, the actuator was placed on slopes with angles of 1.5 and 2.5 degrees. The displacement of the actuator per pulse was 2 and 3 µm, respectively. According to the mentioned specifications, this stepper actuator can be used in different applications, such as X–Y positioning stages in metrology, electrical discharge machines, and miniaturized robots.