x-y velocity

I have a small x-y gantry/bridge with an encoder on x leg and one on the y leg. A deposit nozzle is mounted on the bridge and is moved manually (by hand). I do not care where it is moved to, but I do need to know the velocity (i.e. speed) at which it is moving. Whether moving slow or fast, I need to deposit a consistent amount of material in a uniform bead. Does anyone know of a device or method that translates the x-y movement into a single (vectorized) analog output? The analog output will drive the depositor, from rest (zero) to some maximum (fastest hand motion).

Bruce.

Bruce,
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Bruce,

There are many ways to solve this problem, the hard part is choosing which one fits the job. For that, your cursory description of the task is inadequate.

You don't mention anything about what, if any, control system is present that receives the encoder signals. Also absent is any mention of the encoder resolutions or expected pulse rates. Given the nature of the velocity feedback, a small PLC, single board computer, or even a bread-boarded PIC processor with digital inputs and an analog output are all workable. The math to convert the pulse train intervals into x and y velocities, and thus a motion vector, are relatively simple.

From your description, the velocity scalar is all that's needed, but a direction angle is basically a freebie. What's your budget? One off or multiple units? What's the maintenance support environment? Any bells and whistles desired?

Brian.

You can do this with a one-shot and a filter. The one-shot will output a fixed width pulse for every encoder count and the average of those pulses over time is proportional to frequency. Which in your case is velocity. With one for each axis, you can do the trig and scale for your depositor. You would want high res encoders to filter without too much lag.

Regards
cww