The motion of material handling
Material handling is a great example of an application needing independently controlled axes, point-to-point motion, and controlled acceleration.
What are the main challenges when it comes to implementing motion in a materialhandling process?
Speed —- Typically the material needs to move as quickly as possible.
Accuracy —- Some applications have very tight accuracy requirements and sometimes the parts being moved are very small or delicate.
Flexibility —- If the process changes (say, if different sizes of products are being handled on the same machine) then the control system must be flexible enough to provide quick changeover.
Value added —- Here, products are not just moving from one place to another; there are being processed along the way.
Where can motion technology make the biggest difference in material handling?
Motion technology allows designers to not only simplify a mechanical system, but also make it more flexible. Because a MH system can sometimes have severe time constraints, speed is at a premium.
Safety —-Sometimes the product being moved is a hazardous material; other times are there areas of movement where an operator may reach in or walk through and get hurt.
Algorithms such as "S-curve" acceleration greatly reduce the amount of force not only on the material being moved, but also the mechanics of the system itself. These algorithms usually can be changed on-the-fly. This can be helpful when moving bowls of soup, for example. Empty bowls can tolerate faster accelerations than full bowls, and the time savings can be significant.
Advanced system controllers also allow some processes to be accomplished during the MH phase of an application. While monitoring the position of a move, discrete I/O can be manipulated while the motion is occurring. Sometimes motions are complex and interdependent. These can involve linear and circular movements between several axis, or master-slave arrangements in which one servo axis follows the motion of another device as is the case on a gantry.
Some controllers also let users compensate for system errors. Features such as registration or backlash compensation for lost mechanical motion can net big gains. Same is true for controllers that can monitor torque or tension and then compensate the end motion to stay within applications limits.
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