Controling Position and Velocity of trolley

[MacMosher]

To avoid the problems you are speaking with the PWM in changing directions would I not be able to add an H-Bridge with a slight delay and be able to control the direction that way (which could also be used to control stopping a little better)? That question really isn't for the situation I am in right now but I will be looking at it for a later date when I propose a more appropriate method of control.

As for your questions:

1) CET- Cable Extension Transducer (aka String Potentiometer, Yo-Yo pot.)
2) The appropriate stops will be pre-defined distance of cable extension on the pot. So say I wanted to stop it at 2" and based on tests of how long it takes to slow down have the system shut off the motor at 4" (if the object was approaching the zero of the device).

The Trolley on the track is of a large mass with large friction, and I don't think it will go much farther then an inch after motor drive is turned off.

3) I think I should use the Real-time based software. One because I have access to it, and it will only make system reactions much faster (i.e. to stops).

Many Thanks,

Mac

[Jochen]

HI Mac,

here are some little comments.

Jochen

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@MacMosher wrote:
To avoid the problems you are speaking with the PWM in changing directions would I not be able to add an H-Bridge with a slight delay and be able to control the direction that way (which could also be used to control stopping a little better)? That question really isn't for the situation I am in right now but I will be looking at it for a later date when I propose a more appropriate method of control.
[JK:] An H-bridge allows you to use the motor as an active brake which would be required for a system with low friciton.

As for your questions:

1) CET- Cable Extension Transducer (aka String Potentiometer, Yo-Yo pot.)
2) The appropriate stops will be pre-defined distance of cable extension on the pot. So say I wanted to stop it at 2" and based on tests of how long it takes to slow down have the system shut off the motor at 4" (if the object was approaching the zero of the device).

The Trolley on the track is of a large mass with large friction, and I don't think it will go much farther then an inch after motor drive is turned off.

3) I think I should use the Real-time based software. One because I have access to it, and it will only make system reactions much faster (i.e. to stops).
[JK:] Well, actually a real-time system doesn't make the reactions faster, but it makes them deterministic. That means that if your real-time control application takes e. g. 1 ms to react on a stop, this timing will be stable in all following iterations. On a non-deterministic (e. g. Windows based) system, there will be significant jitter and possibly outliers in the higher millisecond range.

Please note, that LabVIEW RealTime needs some special hardware requirements. If you plan to use a desktop PC please read this document for further information.


Many Thanks,

Mac

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[MacMosher]

Where I am not using a control loop I probably wont see any difference with real time LV then I am assuming.

As for powering the motor I have now moved away from PWM for certain. The trolley being driven is used at a station for the calibration of acuostic transducers and recievers, as such can not deal with the iterferance produced by the PWM while doing calibration while trolley is in motion.

As such I am now going to be using the method I suggested earlier with the DC signal control of a linear voltage regulator.