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View Full Version : [FTC]: Deadbands (axis/motor power restrictions)


JohnFogarty
03-11-2010, 21:30
Hello fellow programmers!
I am currently working on finding a solution to a probable bug which in being a programmer for the last 2 years never occurred. The base joystick to motor control has a bug in it.

4wd

motor[motorD]=joystick.joy1_y1;
motor[motorE]=joystick.joy1_y2;
motor[motorF]=joystick.joy1_y2;
motor[motorG]=joystick.joy1_y1;


It preforms the funtion, but one wheel always continues to spin even when the joystick may only be giving a output of 1 or 2. How do you implement dead bands on your analog sticks to control the motor power output.

RCXRM
04-11-2010, 12:56
Here is the code we've used to create deadbands:

if((joystick.joy1_y1 < 5) && (joystick.joy1_y1 > -5)) joystick.joy1_y1 = 0;
motor[motorD]=joystick.joy1_y1;

NalaTI
04-11-2010, 13:40
I dont have it right here, but ours is something like:


// since joysticks return -127 to 127 values, and since motors react in a
// rance of -100 to 100, this function adds a midpoint deadband and
// adjusts the speed to be within the expected range.

int deadband(int invalue)
{
// if the value is between -27 and 27 then use
// that as the deadband and return 0

if (abs(invalue) < 27) return 0;


// if the value is negative, add 27 to bring the (-27 to -127) to (0 to -100)
if (invalue < 0) return invalue + 27;

// if the value is not > 27 then it already exited, so - 27 and return

return invalue - 27;

}

task main()
{
motor[motorA] = deadband(joystick.joy1_y1);
motor[motorB] = deadband(joystick.joy1_x1);
motor[motorC] = deadband(joystick.joy1_y2);
motor[motorD] = deadband(joystick.joy1_x2);

}

JohnFogarty
04-11-2010, 17:23
Here is the code we've used to create deadbands:

if((joystick.joy1_y1 < 5) && (joystick.joy1_y1 > -5)) joystick.joy1_y1 = 0;
motor[motorD]=joystick.joy1_y1;

haha that looks exactly like what I am trying today thanks:D
I'll just see what works best I may end up going with the other idea too but thank you for your help.
John Fogarty
GForce 3864

coollog
04-11-2010, 19:03
Another way to do it is

int threshold = 12;

motor[motorD] = (abs(joystick.joy1_y1) >= threshold) * joystick.joy1_y1;
...

This basically just zeroes any joystick value that is within a threshold of 0.