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2-D Path Road Help

Howdy Everyone,


I am currently working on a wheelchair simulator platform project that requires me to show a 2-D path road of the wheel chair path. I am currently using a Wireless Data Aquistion System "WLS-9163" with NI-9215 module. I am currently using two incremental encoders that produces position and velocity information. Any ideas on how to start or is there a VI that does similar task?


Any help would be really appreciated.



Mechanical Engineer
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Message 1 of 12

Have you looked at this thread which discusses WLS-9163 configuration?


And this one which discusses connecting to the WLS-9163?


They both discuss using NI DAQmx products.  You can also do a search on the NI-9215 module.


I doubt that you will find a ready-made solution (vi) for your application.

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1. Take a look in the DAQmx examples. There you can find out how to use the counters for incremental encoders. Make some VI's that reads the position (increments from the encoders).

2. Plot the position (I think there are 2 encoders used for position and velocity simultaneous and not 1 for position loop and 1 for velocity loop) on a XY graph where X is one direction and Y the other one - in 2D coordinates).


That should be all. It must be pretty simple.



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To learn more about LabVIEW, I suggest you try looking at some of these tutorials.

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I think my question was not clear. I already have the encoder position and velocity which took me a lot of time to figure out since the wireless system does not have a built-in counter. Repharsing my question: I need to show the road map of the wheel chair "object" from a sky view or bird view. Please find a picture attached explaining.



Mechanical Engineer
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Message 5 of 12

It sounds like all you need to do is feed your position data into an XY Graph. The data input is two numbers in a cluster in a 1D array. Is it true that you already have your position data order sequentially from one point to the next?



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Hello Eric,


I did not understand your question. It seems simple if it only depends on position but how about when turning left or right?

remember that I am using two encoders.




Mechanical Engineer
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Message 7 of 12

I guess a few of us weren't clear on how far you've gotten with the encoders and what your setup is like. Do you have one encoder on each wheel of the wheelchair? Is it this encoder data you are trying to convert to XY position?



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Message 8 of 12

The wheel chair platform has two rollers and there is an encoder attached to each. So far, I have each encoder position and velocity which can be converted to get the velocity and position for each wheel of the wheelchair by conversion ratio. I hope that helped in explaining.

Mechanical Engineer
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Message 9 of 12

OK, so you're question is how to take individual position data from each roller and convert it to an overall position for the wheelchair. I think it will depend on the diameter of your rollers and the spacing between them. Figuring out the math to make this work is part of the fun of this project. As you try to figure this out, you'll be able to experimentally verify just by moving the wheelchair along a known path. That might be the best place to start. Move the wheelchair along a known path with a 90 degree turn at some point and record the data.


I would be surprised if you find an entire solution to this problem here, but someone might have already done it and be able to post a link. However, this is a good place to ask questions about how to store, access, and plot your data. You can write it to a file as you acquire it and process it later... or you can write it to memory for post processing... or you can process it on the fly as it is being recorded.


First it seems like you need to define the mathematical relationships between the combined roller positions and overall wheelchair position.



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