r,theta Gantry System

Sep 17, 2003 2 Replies

Hello All,



I am involved in a project that is looking to build a 2-D gantry system.



We have at our disposal two simple stepper motor based laboratory motion control stages. One is a linear stage and one is a rotory stage. To get the idea of what these things look like, you can see similar products at

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under their Motion Control line of products.



Our plan is to build a polar system, utilising the linear stage as the radius and then mount the rotory stage on top of this to control the angle. The goal is to position a platform under a stationary tool along user defined Cartesian X-Y path.



We are aware that it would be just easier to use two linear stages however we only have one linear stage and as many rotory stages we need.



Does this sound like a viable solution? Can anyone suggest an easier solution?



And finally does anyone know of any sources (Books, articles, papers etc.) that detail the control of such a system? Specifically we are looking for information on how the stepper motors should be moved if we want to move from point A to point B along a line? along a curve?



Sincerely, James McMillan



why not use an "X,theta" system?

your linear stage goes parallel to the X axis, and you get "Y" from R*theta, where R is the length of your boom.... Think of it like a crane mounted on railroad tracks...

The spatial resolution with the rho theta system will not be constant

- but if it meets your needs at max rho that's enough. If you are using some kind of microcomputer control perhaps a PIC card? then what you want is a cartesian polar converter routine - input x,y pair, get rho theta pairs back. This should not be hard to find as freeware.

Brian Whatcott Altus OK

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