Rotating stand

[flybynight420]

I require a rotating stand for a project I wish to do... much like these... http://www.cokerexpo.co.uk/rotating-display-stand.htm ... Which are used in shops

However as you can see they have some preset rotation speeds which have nothing like the accuracy that I will require. I need to control the speed of rotation down to the second e.g. 9 rotations in one minute.

I wondered if you're program might be able to help with this. I'm not an engineer so I might need a bit of help with it, but can one get a component for rotation, and control it with such accuracy?

(Another aside is that it should be silent or close to silent)

Thank you for any help with this

[NullARC]

I'm a novice with Flowstone. However in reading the documentation, I have seen it stated that since the timing is running through the computers software, there can be issues when very precise timing is needed.

You would be better off with a stand alone microcontroller running onboard code that can precisely time the movements that you require.

[DSP]

Whilst NullARC is correct the PC timing isn't perfect, it is plenty fast enough to do what you want (9 rpm).

The key is to have some for of feedback mechanism so that you know where you are. One solution would be to use a stepper motor. Phidgets make a stepper motor controller that would do the job with FlowStone.

Failing that you would need some for of encoder to give you the feedback. again Phidgets make an encoder board that reads the fast data pulses outside of the PC and just send the result back for any error corrections.

[NullARC]

Like I said, a novice... lol

Can you give me an example of an operation that would be too fast for Flowstone to properly time?
Just so that I have an idea what sort of processes would give Flowstone problems.

Thanks!

[DSP]

ok, imagine a motor rotating at 3000rpm and an Opto sensor that is triggered once per revolution. This would send out 50 pulses per second that could be read by FlowStone to calculate the speed of the motor. The issue would be if you used a simple DAQ device with a digital input that the distance between the pulses would be very critical and if the PC had a lot of graphical activity the time read between pulses would not be accurate.

So the solution is to use an external encoder board or counter to count the pulses and read the result at a lower acquisition rate say once a second. So at 3000 rpm you would see a count of 50 in one second, and thus the error would be 1/50th.