Choosing Specifications for a Machine

Choosing the proper specifications for a machine is a prerequisite for tuning. Unless you have a clear understanding of the type of performance needed to push the machine into production, the tuning process will cause more problems and headaches than it solves. Take time to layout ALL the requirements of the machine—nothing is too trivial to consider.

Determine what is the most important criteria. The machine was likely designed and developed with a certain performance in mind. Include ALL peformance criteria in the specification. Do not concern yourself with whether or not the criteria sounds scientific. (i.e. If the motion needs to visably look smooth, put it in the specification. If it can't have any noise, put it in the specification.) At the end of the development phase, the machine's performance should match the performance previously set in the specification. This will ensure that the machine meets its performance goals and that it is ready for production.
Test the machine with realistic motion. Do not simply tune the machine to make short linear motion, when it will make long, s-curve motions in the real world. Unless you test the machine with realistic motion, there is no way to determine if it is ready for production.
Determine some specific, quantitative criteria for identifying unacceptable motion. It's better to be able to tell when a motion is unacceptable than to try and figure out the exact point where acceptable motion becomes unacceptable.
DO NOT pick criteria based on what is the most popular technique of the day. It is important to focus on the things that will get the machine into production. Just because it worked for Machine A doesn't mean it will work for Machine B.

After you have constructed a detailed servo perfomance specification, you are now ready to start tuning your system.