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Fang Gao
06-12-1997, 06:32 AM
We are looking for help from people who have used Labview to control
experiments and collect data involving human (or other!) motion. Labview
looks attractive, but we are unsure whether it can really handle our
current or future real-time control and acquisition needs.

Specifically, we are considering buying Labview to replace "in house"
software for data acquisition and real-time control of experiments running
off PCs (Intel Pentium processor). We collect up to 32 channels of analog
signals collecting up to 1,000 Hz. We currently give subjects on-line
feedback (via monitor) about the x-y coordinates of the center of pressure,
computed from 2 force plates (12 channels) and sometimes concurrent
feedback based on another analog source. Calculations involve multiplying
several channels to a calibration matrix or taking the integral or
derivative of several channels. Additionally, in the future we would like
to do real-time control of external devices like torque motors,
microprocessor, and relays based on several variables, again calculated
from multiple input analog signals (e.g., PID control).

Questions:

1. If you use Labview to display visual COP feedback from 1 or 2 force
plates, do you know the time delay (in ms) involved, especially that due to
calculations?

2. What kinds of real-time control of torque motors, etc have you used
Labview for? With how many simultaneous A/D channel acquisition? what kind
of on-line feedback? What if any limitations did you encounter, and with
what version of Labview?

3. Any comments, pro and con, would be very useful, as would suggestions
for alternatives (we've looked at Tempo and Amlab; Labview has the lowest
up-front cost, biggest company w/longest history, open architecture).

We would like to make a decision soon and will especially appreciate rapid
responses. As usual, we will post a summary.

Thanks,




Fang Gao
Programs in Physical Therapy
Northwestern University Medical School
645 N. Michigan Ave. Suite 1100
Chicago, IL 60611
Tel: (312) 908-6759
Fax: (312) 908-0741