A rotary actuator is a device that converts energy into rotational motion. It is commonly used in various applications, such as robotics, industrial machinery, and automotive systems. Rotary actuators can be powered by different energy sources, including electric, hydraulic, or pneumatic systems, allowing for precise control of movement. These actuators are essential for tasks that require turning or positioning components, such as valves, gears, and robotic arms. They come in various designs, including servo motors, stepper motors, and pneumatic cylinders, each suited for specific applications based on factors like speed, torque, and control precision.