Motion Control IC

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Eric

1. What do these features/parameters do in a motion control IC? How does it work? - end of move flag - maximum error exceeded flag - S-curve profiling Wht is the function and the difference? - PID with feedforward - PID without feedforward Sorry about these dumb questions... Eric
 
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> 1. What do these features/parameters do in a motion control IC? How does it work? - end of move flag - maximum error exceeded flag - S-curve profiling Wht is the function and the difference? - PID with feedforward - PID without feedforward Sorry about these dumb questions... Eric Eric: Most of these chips allow you to command a simple move with destination, velocity, etc. The "end of move" flag allows you to look at a single move to tell you that this move is "done". Usually, this means just that the commanded move has reached the destination; sometimes it also means that the actual position is within some pre-set threshold of the destination (this is usually called "in position"). The "maximum error exceeded" flag is there to tell you that the position error -- the difference between commanded and actual position -- has exceeded some preset threshold, and the servo loop operation has been shut down. This check is intended to prevent runaway conditions if something goes very wrong (like loss of feedback). PID is a feedback algorithm -- its operation is dependent on errors between commanded and actual position. Feedforward provides command output based directly on the desired trajectory -- it can be thought of as your best guess of what effort the servo will require to execute the trajectory, keeping errors to a minimum. Curt Wilson Delta Tau Data Systems
 
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Eric, I have a 20 page booklet entitled "Servo Basics for the Layman". It answers most of the questions you posed. Send me your snail mail address and I'll send it at no charge. This offer is open to anyone else, too. If it weren't in hard copy only, I'd put it on the Control.com site. If too many people respond, give me a little time to get it copied and stapled together. Thomas B. Bullock, President Bull's Eye Marketing Incorporated Industrial Controls Consulting Division 104 S. Main Street, Suite 320 Fond du Lac, WI 54935 PH: 920: 929-6544 FX: 920: 929-9344 E-mail: [email protected]
 
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