Servo motors primarily rely on pulses for positioning. Essentially, a servo motor receives one pulse and rotates by the angle corresponding to that pulse, thus achieving displacement. Because the servo motor itself has the function of generating pulses, it generates a corresponding number of pulses for each angle rotation. This forms a feedback loop, or closed loop, between the pulses sent to and received by the servo motor. In this way, the system knows how many pulses were sent to and received by the servo motor, allowing for very precise control of the motor's rotation and achieving accurate positioning down to 0.001mm.
DC servo motors specifically refer to brushed DC servo motors—these motors are low-cost, simple in structure, have high starting torque, a wide speed range, and are easy to control. They require maintenance, but maintenance is convenient (replacing carbon brushes). They generate electromagnetic interference and are subject to environmental requirements. Therefore, they are suitable for cost-sensitive general industrial and civilian applications.
DC servo motors also include brushless DC servo motors—these motors are small in size, lightweight, powerful, responsive, fast, high-speed, low inertia, smooth rotation, and stable torque, although their power output is limited. They are easily made intelligent, and their electronic commutation is flexible, allowing for either square wave or sine wave commutation. These motors are maintenance-free, eliminating carbon brush wear, and are highly efficient. They operate at low temperatures with low noise, minimal electromagnetic radiation, and have a long lifespan, making them suitable for various environments.