Reset motor and precision movement with the NXT tookit

[Bramgozer]

Hello,
I am having trouble with controlling the motor with the NXT toolkit...
The idea is that the motor gets the command to turn to a specific position, not for a selected amount of degrees..
The motor is attached to a disk divided in 6 compartments. The input comes from the Hitechnic color sensor, and depending on the color the disk should turn to a specific compartment.. But I cant seem to get the reset motor block working, maybe I am interpreting they way it operates wrong..
also, when on fairly high speeds, the motor isn’t very accurate.. since its a servo with feedback, shouldn’t it be able to correct its position if it goes too far?

[Bramgozer]

Here is a screenshot of my current test setup.


Please ignore the mess, I was trying something new.
The light sensor was added in a attempt to stop the wheel from moving at a certain light intensity.



Message Edited by Bramgozer on 05-22-2008 08:33 AM

[nossr]

Bramgozer - I cannot help you, but can you tell me where to get the color sensor VI?  The HiTechnic VIs do not compile-to-brick for me, being password protected. 

The reference to "FTC demonstration competition" did not lead to anything.

You mentioned in a previous thread that you asked HiTechnic whether they support the color sensor in LabView -- any reply from them?

- nossr

[Bramgozer]

Yes they sent me an email with the beta blocks for their sensors in labview, please sent me a PM and I'll forward the mail to you 🙂

[nossr]

Bramgozer - Thanks for the reply.  I don't know what a PM is but you can forward the email you mentioned to roger.noss@sbcglobal.net

- nossr

[DJDDA]

also, when on fairly high speeds, the motor isn’t very accurate.. since its a servo with feedback, shouldn’t it be able to correct its position if it goes too far?

Are you talking about the issue mentioned here?

(Edit for tags.)

Message Edited by DJDDA on 06-11-2008 02:01 PM

[Bramgozer]

sort of... but that didnt every really come to a clear solution.. it just seems odd to me that a high-tech motor like the NXT servo would need that much external control to gain a reasonable amount of precision..

[DJDDA]

Unfortunately, it would seem that your "clear solution" is not available at this time. The current conclusion, as I understand it, is that the NXT servos cannot be controlled with precision except as part of a program which is stored and executed from within the brick itself. That this conclusion is unpalatable does not invalidate it.

[iaqchan]

Sorry by my english ...

in fast movements when you turn off the motor they pass the position, I have one projet with the same problem and I correct this including one control in power motor, when the position is near the stop position I down the power level motor, but never "0" with 5 or 10 they stop correctly, if you wish can put more steps and down first to 25 and after to 10 with comparators or but one linear control to power=|endposition-position+1| * 10 and one comparator and if power > 75 then power = 75.

I hope that work.

Now, one deal, can you send the VI to hitechnic color sensor and other VI that you have to hitechnic ?