Originally Published MEM Spring 2004
MOTION CCONTROL
Key Specification Questions to be Answered|
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Medical electronic system designers cannot afford to take manufacturers' component performance specifications at face value. A host of circumstances might make ultimate application conditions very different from conditions under which the specified motion components were tested. Some important questions that should be asked of critical specifications follow.
Specification: Accuracy, Repeatability, Flatness, and Straightness
- Is the specification for the entire stage system or for the subcomponents?
- Is the specification for a multiaxis stack or for an individual axis?
- Does the specification cover performance over the entire travel or performance level per some unit of measurement?
- Where is the point of measurement?
- What type of mounting surface is required to repeat metrology test results?
- Does the performance measurement include a load?
- What statistical methods were used to generate the performance specification?
- Were the tests performed on each axis individually or as a stack?
- What were the velocity, dwell times, and duty cycles of the moves during the test?
- What was the increment between data points?
- What were the environmental conditions during the test?
Specification: Resolution
- Is this specification measured or calculated?
Specification: Acceleration
- Was the stage unloaded during the acceleration test?
- What was the following error during the test?
- How much heat will the motor generate at the specified acceleration?
- What is the duty cycle at the advertised acceleration?
Specification: Direct Load, Axial Load, Moment Load
- What is the service life rating of the stage at stated loads?
- Is the load capacity a system load rating or the rating of subcomponents?
- Is the moment load rating static or dynamic?
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