Rotate in negative degrees

[Shadowstep]

Hay I have a program I'm writing and I am using some kind of loop and in that loop an If statement.
so my has a head on a motor so it has to constantly look left and right. What I do is I say rotate 15 degrees and so it looks left but then how do I get it to rotate back in the direction it came from?


thanx

[Aswin]

Hi,

You use the tachometer from the motor to do this. You can set a target, rotate to the target, then set another target (your starting position) and then rotate back. You'll find the exact commands explained in this tutorial.

[Shadowstep]

I don't really get the meaning of this. a tacho meter checks how fast it goes not? and 720 tacho = 720 rounds? or 720 degrees?

thanx

[skoehler]

I don't really get the meaning of this. a tacho meter checks how fast it goes not? and 720 tacho = 720 rounds? or 720 degrees?

No. The Tachometer is a counter in this case. It counts, how far the motors have rotated. Movement in the one direction is positive, in the other direction it is negative. A tachocount of 720 means, that the motor has rotated 720 degrees.

[Shadowstep]

Ok thanx a lot I will look in to that tonight and let's pray it works now :p

[roger]

Hi Shadowstep,
I understand why you were confused. Lego calls the sensor in the motor a tachometer, but your are correct that definition of a tachometer is an instrument that measures speed of rotation. It might better be called an odometer (in English), because it measures distance, not speed. But we are stuck with the Lego term. BTW, does anyone know what Lego called it in Danish?
Roger

[bullestock]

Hi Shadowstep,
I understand why you were confused. Lego calls the sensor in the motor a tachometer, but your are correct that definition of a tachometer is an instrument that measures speed of rotation. It might better be called an odometer (in English), because it measures distance, not speed. But we are stuck with the Lego term. BTW, does anyone know what Lego called it in Danish?
Roger

AFAIK, it does not have a Danish name. LEGO does not sell a Danish version of the NXT.