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Servo motor turn measuring 
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Rookie

Joined: Fri Oct 17, 2008 8:08 pm
Posts: 2
Post Servo motor turn measuring
Hi,

I have connected ultra sonic sensor to one of servo motors, and what I want to do is to spin sensor in 90 degrees and back as precise as possible, but the wire (between main board and sensor) because of friction with the main board makes an error in sensor rotation. Does any one know solution for that, maybe there is way to measure angle of servo motor?

Thank you!


Fri Oct 17, 2008 8:13 pm
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Joined: Sun Mar 02, 2008 9:41 am
Posts: 25
Post Re: Servo motor turn measuring
what exactly do you mean by "makes an error in sensor rotation"?

the servo motor provides 360 ticks per full rotation. so if you move the motor 90 ticks left or right you ll have turn 90 degrees.

To turn your whole robot 90 degrees more calculations are needed but the concept still holds.

somebody had made a post here with a function regarding rotation (about 6 months ago), it would help u to read this and understand the whole concept,, i think anyway.

thanks,
giannis


Mon Oct 20, 2008 4:55 am
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Joined: Wed Jan 24, 2007 10:42 am
Posts: 613
Post Re: Servo motor turn measuring
If this is an FTC question, you need to ask this in the FTC area of the forums or you will not receive proper support.

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Timothy Friez
ROBOTC Developer - SW Engineer
tfriez@robotc.net


Mon Oct 20, 2008 1:24 pm
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Joined: Sat Mar 01, 2008 12:52 pm
Posts: 1030
Post Re: Servo motor turn measuring
why do FTC members get proper support but no regular / general users?

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regards,
HaWe aka Ford
#define S sqrt(t+2*i*i)<2
#define F(a,b) for(a=0;a<b;++a)
float x,y,r,i,s,j,t,n;task main(){F(y,64){F(x,99){r=i=t=0;s=x/33-2;j=y/32-1;F(n,50&S){t=r*r-i*i;i=2*r*i+j;r=t+s;}if(S){PutPixel(x,y);}}}while(1)}


Mon Oct 20, 2008 2:31 pm
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Professor

Joined: Fri Sep 19, 2008 1:22 am
Posts: 200
Post Re: Servo motor turn measuring
Tim wasn't talking about good support v/s bad support. He as talking about getting different answers. For example, if he is using pure LEGO parts then his question requires an answer that assumes he is using the LEGO motors as servos. However, if he is using a Tetrix robot which has a real servo controller plugged into the NXT then his question requires an answer that assumes he is talking about actual servos instead of LEGO motors. It isn't about quality of service. It is about the context of the question.

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Jeff McBride
Benson Robotics Club


Mon Oct 20, 2008 3:35 pm
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Joined: Sat Mar 01, 2008 12:52 pm
Posts: 1030
Post Re: Servo motor turn measuring
thx, then I'm relieved... ;)

_________________
regards,
HaWe aka Ford
#define S sqrt(t+2*i*i)<2
#define F(a,b) for(a=0;a<b;++a)
float x,y,r,i,s,j,t,n;task main(){F(y,64){F(x,99){r=i=t=0;s=x/33-2;j=y/32-1;F(n,50&S){t=r*r-i*i;i=2*r*i+j;r=t+s;}if(S){PutPixel(x,y);}}}while(1)}


Mon Oct 20, 2008 5:13 pm
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