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Subject: 
Re: Power Function control with RCX and BrickOS
Newsgroups: 
lugnet.general, lugnet.technic, lugnet.trains, lugnet.robotics
Date: 
Sat, 26 Jan 2008 21:43:19 GMT
Viewed: 
19419 times
  
In lugnet.general, Beat Felber wrote:
   Thank you very much for that fine piece of software Bob!

After reading your post I immediately run in my LEGO room to grab an RCX and the IR tower to test your software. Well, I had to find out that I had not enough batteries at home and thus had to get some overpriced ones at the next gas station :-)

Download of the firmware as well as the program worked fine. The program runs without problems and the Bulldozer reacts immediately. Great!

I have a few issues though where I’d like to ask you for some hints:
  1. The rotation sensor sets zero at the position it was during start of the program. By stepwise moving the axle in one direction, the PF motor runs first at max. speed and then gets slower and slower. So PWM works fine. But how can I change the program in a way that from zero position the speed increases when turning the axle of the rotation sensor? Currently it decreases stepwise from max. speed which makes it somewhat difficult to control the Bulldozer (or whatever model using the PF motors).

  2. Furthermore I found out that turning the rotation sensor in one direction, the motor runs in for example forward direction. I thought by turning the connector plate on the sensor interface of the RCX would change direction of revolution of the motor when the sensor is turned in the same direction as before. Of course, I tried all four possible orientations of the connector, but the motor still turns always in the same direction when turning the axle of the rotation sensor forward? Is this the correct behaviour?

  3. Finally, does it happen to you too, that the rotation sensors loose calibration very fast? Just after playing around for a few cycles (forward, backwards, forward...) The zero position is not at the same place any more.
If you could give me some hints on how to overcome these issues, this would be much appreciated. You will have to know that I am everything else than a Mindstorms professional :-)

Thanks again for your work

Beat

PS. My intention is to build a proper remote control with two mechanical joysticks, each coupled to two rotation sensors to be able to control all four functions of the Bulldozer at the same time.

Well this was just a quickly hacked out example program to show how to use the library function that i wrote. i realized at the time that the PWM started out at fastest and went to slowest but i had run out of steam and never really got back into it to fix it. i’ll probably spend some more time this week and make the changes you suggested.

i will have to play around to see if i notice the calibration issues you mentioned. one suggestion is to build a ratcheting mechanism like in the 8288 using the bionicle teeth and the rubber part that has 2 axle holes.

bob



Message is in Reply To:
  Re: Power Function control with RCX and BrickOS
 
Thank you very much for that fine piece of software Bob! After reading your post I immediately run in my LEGO room to grab an RCX and the IR tower to test your software. Well, I had to find out that I had not enough batteries at home and thus had to (...) (17 years ago, 26-Jan-08, to lugnet.general, lugnet.technic, lugnet.trains, lugnet.robotics, FTX)

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