Motion Control Design Considerations

There are, of course, a number of things that might go wrong in the design and implementation stage. Here we will focus on four common, related mistakes that can easily be avoided in designing a machine to operate as intended.

First, it is not uncommon to see high performance components coupled to a load with ordinary gearboxes, belts or compliant couplings. Dont do this. When designing with high performance motion components it is important they be paired with rigid, high quality couplings and gearboxes. Direct drive systems are another option that can eliminate compliance issues altogether.

A second common error that can be a bit more difficult to diagnose is that of connecting the drive and motor with lower quality cables. Moderate to low quality cables are often the cause of intermittent noise issues that can have a great impact on overall system operation.

Improper cabling is often a result of inadequate budgeting, so plan for this expense up front, and wherever possible, use manufacturer recommended cables.

Third, mismatched motors and drives result in underperformance and overheating, so these items should be specified up front as a team. Where that is not possible or was missed, work after the fact to make certain the drive and motor are matched to provide optimized performance.

Finally, mismatched feedback devices will also result in the underperformance of a machine. Many different feedback options exist, and each offers unique advantages in terms of performance, ruggedness and cost.

Mismatching components is often the downfall of intended machine performance. It is akin to purchasing a 40-foot yacht and a 25 HP motor to make it go -- they each have their place depending on the purpose of the machine, but they were never intended to work as a team.

Being proactive- motion system design tips

Of course all of this is often easier said than done, particularly with ever-tight budget and engineering resources. But there is nothing like up-front planning to smooth the design and implementation process of a machine, and there are resources available to help.

Take as much time as necessary to define the machine structure and motion performance needs based on mass, force and motion profiles for each axis of motion. Budget accordingly.

Put life-costconsiderations ahead of up-front-costconsiderations. As an example, systems that employ direct drive brushless motors will have a higher up front cost than systems using gearboxes, drives or other mechanical components. But direct drive systems require significantly less maintenance over the life of the system. This maximizes machine uptime and minimizes maintenance costs.

Partner with a reputable supplier who offers a breadth of expertise, engineering resources and available product options to meet specific application needs. Dont be shoehorned into a solution that wont work as needed because it is all that the vendor has to offer. Utilize tools that manufacturers make available, such as software that can help solve motion system requirements and identify components that will meet those requirements, and applications engineers who can help fill in the blanks.

Consider the productivity and performance of various options. Conventional mechanical devices that create linear motion can keep up front costs down and are a good option for many machines, but they can also limit bigger-picture performance in systems that will use higher performance technologies in their other axes of motion. The key is selecting the optimum product for each axis based on an understanding of the total machine requirements. Then seek a working knowledge of new technology that will be part of the system, prior to the purchase and installation of each component.