Motion Control for Speed, Precision and Repeatability
Motion is precise control of a motor, not just speed, but position also. It is often used for applications that require an extremely high level of repeatability or a very aggressive acceleration and/or deceleration. Machines like CNC mills and lathes, stamping machines and traverses on take up spools are but a few of the machines you will find motion control.
How Motion Control Works
Motion is achieved by combining a servo motor with a servo amplifier (drive) and a controller. Controllers can be built into an amplifier, be part of a PLC or be a stand-alone piece of equipment. The controller can be programmed to track the number of rotations, or partial rotations, that the motor has made and correlate that into a distance measurement.
Take for instance a rotating table. If the table has six equally spaced clamps around its circumference. One can program a motion system to stop a clamp at a conveyor, pick up a piece and rotate 60 degrees (1/6 of a turn) so the next clamp can pick its piece. As the table rotates at some other position, or maybe multiple other positions, some operation can be done to the piece. The acceleration, deceleration, speed, and wait time between movements are controlled by the controller. The amount of rotation is also more precise than using other methods such as proximity switches or limit switches, so the lining up of the part to other operations is constant and repeatable over years of operation.
This is just one example of motion, you can find other examples virtually everywhere from industrial machines, to medical devises, to robots, to the over the field cameras at sporting events.
- Stu, Control Specialist