Servo System Components

A servo system essentially comprises an intelligent servo drive and a servo motor that operates with a PLC or CNC to perform complex, specialized moves in one or more directions. These complex and specialized moves, are collectively known as motion control.

A servo system mainly consists of:

1. Servo motor

A servo motor moves machinery in a single axis of motion. Electrical motors are driven by magnetic fields. Motors have a stationary field generated by the magnets of the motor and a rotating or movable field called stator winding or armature. They operate on the principles of synchronous motors. All rotary motors have some type of bearing that supports the rotor at each end.

2. Load

The load is the machinery and equipment that each motor drives. It is everything connected to the output shaft of a motor, including the shaft itself. A servo system delivers and converts motion to a load via one or more of the following mechanical techniques:

Direct drive

Motor connected to a rotating table.

Screw drive

Motor connected to a lead screw carrying a slide.

Rack and pinion

Motor connected to a cogwheel that moves a rack

Belt and pulleys

Motor connected to rollers that move conveyor belts or chains and sprockets

3. Feedback device

Every closed-loop servo system needs at least one device to return feedback information from each motor (or load) to servo drive. Depending on the feedback device, feedback is transmitted back to the servo drive in the form of digital signals or analog signals. Two types of feedback devices are supported:

Encoder - returns analog or digital signals

Resolver - returns analog signals

4. Servo amplifier (servo drives)

The servo drives comprise a three-phase power supply, and high-performance control unit all housed in a single enclosure. The several control loops are realized in the micro controller.