Motion Control Engineering is a broad brush discipline that covers all situations and conditions of mechanical motion that is controlled by a motor or some other prime mover.
Let’s consider only rotary motors for this discussion and only acknowledge that linear motors and other prime movers exist.
I believe that the best motion solution is the one that meets the specific application’s requirements and at the lowest cost. Using a motor technology that is more sophisticated than what the application needs adds cost. I’ve seen solutions proposed and sold that met the sales engineer’s sales goals, not the most cost effective solution for that specific application. For example: a motor that turns a fan blade does just that, it turns it. It might turn clockwise or counter clockwise. It might spin it at variable speeds, but it doesn’t need to stop in a certain position. So using a servo motor to turn a fan blade that can position a particular fan blade to the 12 o’clock position when it’s told to stop would be overkill and a very expensive solution. A reversible, multi-speed AC motor might be the best cost effective solution.
The purchase price of the best motor technology isn’t the only “cost factor” either. Consider the cost of the motor’s control and where and how the control is mounted:
- How are the motor, power and feedback cables connected to the controller?
- What are the costs for the enclosure, cables and connectors?
- How much physical space does the whole system occupy?
- Does the whole system consume more factory floor space than desired, resulting in fewer machines per square foot?
- Would an integrated motor system provide a lower “installed” cost than separate components?
- Would it result in a smaller factory floor foot print resulting in more equipment per square foot?
- How easy/difficult is it to get the system up and running?
So what are the criteria for choosing the best motion control solution?
The first test is price and performance, or what are the least expensive motor and control that meet the application’s requirement?
The least expensive to the most expensive motor technologies are:
- AC Motors with no control. (Line driven.)
- DC Motors and controls
- AC Motors and controls
- Brushless motors and controls
- Stepper motors and controls
- Servo motors and controls
- Direct drives and controls
To choose the best motion control solution we have to ask more questions and those will be asked…and answered in following postings to this blog.