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We can't get speed control for the Tetrix DC motors.
http://www.robotc.net/forums/viewtopic.php?f=52&t=1020
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Author:  aybose [ Tue Dec 09, 2008 7:35 pm ]
Post subject:  We can't get speed control for the Tetrix DC motors.

We do not have any change in the speed in the Tetrix standard DC 12V motors although we seem to be editing it. Here is our code. When we plugged in the Lego NXT motors, we did get speed variablity.

#pragma config(Hubs, S1, HTMotor, HTServo, none, none)
#pragma config(Motor, mtr_S1_C1_1, motorD, tmotorNormal, PIDControl)
#pragma config(Motor, mtr_S1_C1_2, motorE, tmotorNormal, PIDControl)
//*!!Code automatically generated by 'ROBOTC' configuration wizard !!*//

#include "JoystickDriver.c"

task main()
{
while (true)
{
getJoystickSettings(joystick);

motor[motorD] = 100;

}
}

Just something as simple as this, without any joystick input, does not change at all when it is run. When we do add in the joysticks, there is no speed variabilty as well.
Thanks!

-Francis Parker WARLORDS

Author:  Jeff McBride [ Tue Dec 09, 2008 9:43 pm ]
Post subject:  Re: We can't get speed control for the Tetrix DC motors.

Do you have the shaft encoders installed? If not, turn off PID control. What is probably happening is:

- You are asking for a particular speed
- The controller applies power to the motor
- There is no data coming from the shaft encoder which it interprets as the motor being stopped
- The controller applies more power to the motor to try to get it moving
- Round and round until (more or less) full power is being applied.

Author:  aybose [ Tue Dec 09, 2008 10:47 pm ]
Post subject:  Re: We can't get speed control for the Tetrix DC motors.

How do we install shaft encoders and what exactly are they?

-Francis Parker WARLORDS

Author:  Jeff McBride [ Wed Dec 10, 2008 12:08 am ]
Post subject:  Re: We can't get speed control for the Tetrix DC motors.

They look like the attached picture. Your kit should have come with two of them and with instructions for assembling them.

Attachment:
ShaftEncoder.JPG
ShaftEncoder.JPG [ 22.35 KiB | Viewed 4906 times ]


Note: BE VERY CAREFUL. Even with the FTC Team 20% discount they cost about $64 each.

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