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Motor Arm, Encoders, and Braking Help Please 
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Joined: Sun Nov 30, 2008 7:34 pm
Posts: 2
Post Motor Arm, Encoders, and Braking Help Please

We've been having problems programming the DC motors with the encoders. We have a DC motor at a 12:1 gear ratio rotating an 11 in. arm, and we were testing the strength of the motor. On our first test we used a 1 lb weight, because the motor should have been for sure able to handle that weight the way we geared it. Sometimes it worked exactly as it should have, rotating the weight up a little and then holding it there, but sometimes it would coast back down after rotating it up. Is there any reason that the program would work sometimes I ran it, but wouldn't work other times? Here it is:

void runMotor (int degrees)
nMotorEncoder[firstPivot] = 0;
while (nMotorEncoder[firstPivot] < degrees)
motor[firstPivot] = 100;

task main()
bFloatDuringInactiveMotorPWM = false;
runMotor (50);
motor[firstPivot] = 0;

Thank you for your help.

Sun Nov 30, 2008 8:12 pm

Joined: Sat Nov 29, 2008 4:21 am
Posts: 4
Post Re: Motor Arm, Encoders, and Braking Help Please
We also used a motor to power an arm and with only a 3:1 ratio. 50 clicks on the motor encoder is almost noting it seems to take a few thousand counts to a single rotation of the motor. We tested ours by programing the motor to respond to a joystick position. Simply set the motor power to equal the position of one of the axis on one of the sticks and you can test if your arm will hold in any position it can reach. ours does and it has another arm and motor on top of it.

Ian McBride
Benson Robotics Club

Mon Dec 01, 2008 5:56 pm
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