Motion control systems are the backbone of many applications in a wide array of industries. Their use provides greater precision, reliability, and efficiency.
Many of us work alongside motion control systems already. Others might encounter a motion control system in their workplace as the systems grow in scope and ability. Therefore, it is essential to understand each motion control component.
Open and Closed-Loop Motion Control Systems
First, motion control systems generally break down into two types: open-loop and closed-loop. Open-loop systems provide no feedback—processes run until completion, and the system can’t change the variation in its output. For example, open-loop traffic control systems operate on a time basis. Traffic lights always switch after a pre-determined time slot, no matter the traffic density.
On the other hand, closed-loop systems add feedback—the output affects the input quantity to maintain the desired output value. For example, closed-loop traffic control systems use time slots based on the density of traffic. Once a computer in the network measures a certain level of traffic density, the traffic light changes.
Each system has its advantages and disadvantages. Open-loop systems are typically more affordable, while closed-loop systems can achieve greater precision and complexity.
The Four Essential Components of Motion Control Systems
Learning about each motion control component is a crucial aspect of motion control training. There are four essential motion control components: motion controller, drive, motor, and feedback device.
Motion controllers are the brains of motion control systems. They generate and calculate the commands that guide a machine’s function. Additionally, they can adjust their commands to meet the required system outputs. You can choose motion controllers based on the number of axes, update time, D/A resolution, and the motion supported.
Drives convey the amount of current and voltage needed to the rest of the motion control system. Simply put, drives receive information from the motion controller and relay it to the motor. There are six types of drives: digital, analog, linear, switching, stepper, and servo drives. Each drive has a unique function and ability. For example, digital drives contain processing abilities, while analog drives don’t. Linear drives are used for low-power applications while switching drives are used for high power applications.
Motors are the muscle of motion control systems. They convert electrical energy into mechanical energy, producing the torque required to move to the target position. While there are many types of motors in motion control systems, they’re all either AC or DC motors. AC motors are more versatile than DC motors. They have an adjustable torque limit, controlled acceleration, and fewer power line disturbances. On the other hand, DC motors are more basic and simple to use. They are easy to install and have a high starting torque, but they can be more expensive in the long run for high power units.
Lastly, feedback devices offer feedback for motion controllers to make adjustments to provide the necessary output. It’s crucial to understand feedback devices are only included in closed-loop systems. Encoders are the most popular feedback device, providing information on position, velocity, and direction to the motion controller.