Mindboards

Hi, I am pretty new to NXT. I am working on a project were I am using Firgelli L12 100mm actuators to move a series of panels.

I'm running into some problems and I'm not sure if I am doing something wrong or if it is a glitch with NXT-G or the block for the actuators. I know some of you use them so any help would be great. I am getting frustrated.

I am setting up simple loops to have the actuator extend a certain distance upon the pressing of a touch sensor and then retract that same distance with another push of the touch sensor. I just set it up as a Wait Touch Sensor followed by the Block for the actuator, another Wait Touch Sensor and another Acuator Block. All of this is inside a infinite loop.

I noticed a couple small problems such as the MM measurement is off on the actuator (if i tell it to extend 60 mm it may extend 64 or 66, but it stays pretty consistent so I can allot for that) and I cannot turn off "Wait for Completion" or the actuators don't run correctly at all. (but I can live with that if i really have to)

The real problem that I am facing is when I am testing the actuators they seem to run the loop correctly a certain amount of times then randomly will only retract 6mm or so instead of the full 60mm.
It would move from these points: 0mm to 60mm, 0, 60, 0, 60, 54
Then after only retracting that small amount it would go back to extending 60mm and retracting 60mm but the original axis/pivot point for the actuator is way off by then. It just wants to rip my piece apart by that point because it is extending further then it should.

The loop is so simple that I can't figure out where it is going wrong. It seems to happen at random. Is this a glitch with the block or a drawback with NXT-G. I don't know how to program but would programming in RobotX or NXC fix this problem. Any advice would be great!

Thanks in advance.
Eric

Eric,

Sounds like it may be a glitch in NXT-G that you'll have to find a way to work around. One option would be to build a touch sensor into the panel so it knows when to stop.

Actually, it sounds like you're using more than one panel/actuator/touch-sensor, so that may not be an option.

Are you running three loops at the same time? That may be the cause of the overextension. The NXT is trying to do several things at once, so it does them all a little worse. (less accurate)

Another suggestion is to add lots of resets into the program. Reset the rotation sensor often (before starting the moves).

If you're still having issues, you may want to go ahead and post the program.

Steve