The controlled objects of a servo drive system are the displacement and speed of the machine tool's coordinate axes, and the actuators are servo motors or stepper motors ; the part that controls and amplifies the input command signals is called a servo amplifier (also known as a driver, servo unit, etc.), which is the core of the servo drive.
A servo system is essentially a follow-up system. The controlled variable is either displacement or its derivative with respect to time. To define a follow-up system, it's a system whose output reproduces the input signal as quickly and accurately as possible. Metrics for measuring this include overshoot and latency.
A servo system is an automatic control system that enables the output controlled variables, such as the position, orientation, and state of an object, to follow any changes in the input target (or given value). The main task of a servo system is to amplify, transform, and regulate power according to the requirements of control commands, making the torque, speed, and position control of the drive device highly flexible and convenient.
A servo system mainly consists of three parts: a controller, a power drive unit, a feedback unit, and a motor. The controller adjusts the control quantity according to the difference between the setpoint of the CNC system and the actual operating value detected by the feedback unit.
As the main circuit of the system, the power drive device, on the one hand, applies the electrical energy in the power grid to the motor according to the magnitude of the control quantity, and adjusts the magnitude of the motor torque; on the other hand, it converts the constant voltage and constant frequency power grid supply into the AC or DC power required by the motor according to the motor requirements; the motor then drives the mechanical operation according to the power supply.
What are some common servo systems?
Servo systems include three types: open-loop, semi-closed-loop, and closed-loop.
Open: Only drive signal, no feedback signal.
Semi-closed: There is a feedback signal, but no compensation is performed.
Closed: There is a feedback signal, and the feedback signal and the drive signal are compared and then compensation is performed.
The above refers to the position loop. Ultimately, in a mechanical system, accuracy is reflected in positional deviation. Therefore, the opening and closing loops and feedback of the entire machine are all related to the position loop.
Modern servo motors typically have built-in encoders that connect to the driver to detect the motor's speed. The driver then compares and adjusts the output. This feedback loop is the speed loop. Compensation is applied to the motor speed. Therefore, such a system is called a semi-closed loop.
