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View Full Version : First Year with Java, Help Requested


Sotha
10-02-2011, 18:52
This is our first year using Java, our team does not have any programming mentors so I have pretty much been hung out to dry. I've been banging my head against the wall because I can not get this code to work.

Here is our code: (Some things are commented out due to me trying to debug.

/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2008. All Rights Reserved. */
/* Open Source Software - may be modified and shared by FRC teams. The code */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project. */
/*----------------------------------------------------------------------------*/

package edu.wpi.first.wpilibj.templates;


import edu.wpi.first.wpilibj.Compressor;
import edu.wpi.first.wpilibj.SimpleRobot;
import edu.wpi.first.wpilibj.Jaguar;
import edu.wpi.first.wpilibj.Joystick;
import edu.wpi.first.wpilibj.RobotDrive;
import edu.wpi.first.wpilibj.Timer;
import edu.wpi.first.wpilibj.Watchdog;



/**
* The VM is configured to automatically run this class, and to call the
* functions corresponding to each mode, as described in the SimpleRobot
* documentation. If you change the name of this class or the package after
* creating this project, you must also update the manifest file in the resource
* directory.
*/
public class Team2501Robot extends SimpleRobot {
RobotDrive drive = new RobotDrive(1, 2, 3, 4);

/* Jaguar frontLeft = new Jaguar(1); // Front Left Motor
Jaguar frontRight = new Jaguar(2); // Front Right Motor
Jaguar backLeft = new Jaguar(3); // Back Left Mottr
Jaguar backRight = new Jaguar(4); // Back Right Motor
Jaguar armLower = new Jaguar(5); // Motor for Arm
Jaguar armUpper = new Jaguar(6); // Upper Motor for Arm
Compressor c = new Compressor(6,7);
*/


Joystick leftStick = new Joystick(1); // Drive Stick
Joystick rightStick = new Joystick(2); // Arm stick
double magnitude = leftStick.getMagnitude(); // Magnitude
double direction = leftStick.getDirectionDegrees(); // Direction
double rotation = leftStick.getX(); // Rotation
double rmagnitude = rightStick.getY();


public void autonomous() {
for (int i = 0; i < 14; i++){ // Autonomius Mode
// c.start();
drive.drive(0.5, 0.0); // Drive forward at half speed
Timer.delay(2.0); // Wait two seconds


}
drive.drive(0.0, 0.0); // Stop
}

public void operatorControl() {
getWatchdog().setEnabled(true);
while (isOperatorControl() && isEnabled()){ //loop during telop
// c.start();
drive.mecanumDrive_Polar(leftStick.getDirectionDeg rees(),leftStick.getMagnitude(), rightStick.getY());
if(rmagnitude > 0.0)
{
/*armLower.set(rmagnitude);
armUpper.set(-rmagnitude);*/
}
else if (rmagnitude < 0.0)
{
/*armLower.set(-rmagnitude);
armUpper.set(rmagnitude);*/

}

else if(leftStick.getRawButton(4)){ // For Strafe Left
/*frontLeft.set(0.5);
backRight.set(0.5);
frontRight.set(-0.5);
backLeft.set(-0.5); */
}

else if(leftStick.getRawButton(5)){ // For Strafe Right
/* frontLeft.set(-0.5);
backRight.set(-0.5);
frontRight.set(0.5);
backLeft.set(0.5); */
}

}
Timer.delay(0.005);
// c.stop();

}
}

mwtidd
10-02-2011, 19:09
If its your first year with Java. Maybe start by using arcadeDrive, and then once you get that running, upgrade to mecanum

also your polar code is wrong
first param is magnitude, second direction, third rotation
also you could try cartesian

having your jags and drive mapped to the same ports may cause problems later

Aaron V
10-02-2011, 20:43
I agree with lineskier on all points; it would be simpler to start with arcade drive, then upgrade to mecanum later. On the other hand I can imagine your team wants this to work soon, so here's my interpretation.

First of all, you don't need the while loop. It doesn't hurt, but the system already calls the operatorControl method in a loop - getting rid of it cleans things up.

Secondly, I strongly recommend you use Cartesian drive. It's just much simpler, and I find it's more intuitive to drive (it's a lot like an FPS). Even if you don't plan on directly mapping controls in this way, it's way easier to conceptualize - x and y directions and rotation (just put 0 for the gyro until you understand it).

The other thing is that for simplicity reasons, you should only use the drive method to control the drive system. None of this manual Jaguar control for the drive system - it could conflict with the drive method. (Don't worry about the arm control, that should be fine.)

When I write semi-complex drive code, I like to set variables at the beginning as my drive values. So in this example, I'd set three variables as: xMagnitude, yMagnitude and rotation. Then I'd manipulate these values and after that call the drive method.

By setting variables I can start with a controller input, then adjust them as I see fit. It also makes the code way simpler.

One final thing that is probably a fundamental misconception is that you need to set values that you want to change (ie. rmagnitude) in the operatorControl method. Otherwise it sets the value to whatever the joystick was at when you start the robot and doesn't change. Values that won't change during the runtime can stay above the method (ie. RobotDrive) (There's a lot of complexities as to why, but that's not important now - let me know if you want more info later.)

So, unless I missed something, here is working code for you:

public void operatorControl() {
getWatchdog().setEnabled(true);

double xMagnitude = 0; // unless you have a spare axis for this.
double yMagnitude = leftStick.getY();
double rotation = leftStick.getX();
double rmagnitude = rightStick.getY();


if(rmagnitude > 0.0)
{
armLower.set(rmagnitude);
armUpper.set(-rmagnitude);
}
else if (rmagnitude < 0.0)
{
armLower.set(-rmagnitude);
armUpper.set(rmagnitude);

}

else if(leftStick.getRawButton(4)){ // For Strafe Left
xMagnitude = -0.5;
// If you want, you could set yMagnitude or rotation to zero here.
}

else if(leftStick.getRawButton(5)){ // For Strafe Right
xMagnitude = 0.5;
// If you want, you could set yMagnitude or rotation to zero here.
}

}
Timer.delay(0.005); // I don't know why this is here - you don't really
// need to slow anything down

drive.mecanumDrive_Cartesian(xMagnitude, yMagnitude, rotation, 0);




I did make a few assumptions and didn't explain everything, but I hope I communicated most of it to you. Let me know if you have questions.

EDIT: I just realized I didn't do anything about your compressor. Just start it in the autonomous or even the initializer (if you know what that is) and leave it. I don't see a reason to turn it off as the power of the robot should just turn it off.

ccresta1386
27-06-2014, 14:05
We are also in our first year and need help with programming. Our forward/backward and rotation works but strafing does not work.

drive = new RobotDrive(1, 3, 2, 4);
driverStick = new Joystick(1);
shooterStick = new Joystick(2);
robotHeadingGyro = new Gyro(1);


double rotation = driverStick.getZ()*-1 / 2; if (driverStick.getRawButton(3)){
rotation += .4;
}else if(driverStick.getRawButton(4)){
rotation += -.4;
}

drive.mecanumDrive_Cartesian(driverStick.getX(),
rotation,
driverStick.getY()*-1,
0);// we plan on putting a gyro in when the strafe works

notmattlythgoe
27-06-2014, 14:08
We are also in our first year and need help with programming. Our forward/backward and rotation works but strafing does not work.

drive = new RobotDrive(1, 3, 2, 4);
driverStick = new Joystick(1);
shooterStick = new Joystick(2);
robotHeadingGyro = new Gyro(1);


double rotation = driverStick.getZ()*-1 / 2; if (driverStick.getRawButton(3)){
rotation += .4;
}else if(driverStick.getRawButton(4)){
rotation += -.4;
}

drive.mecanumDrive_Cartesian(driverStick.getX(),
rotation,
driverStick.getY()*-1,
0);// we plan on putting a gyro in when the strafe works




Are you positive that your wheels are oriented correctly?

ccresta1386
27-06-2014, 14:11
Are you positive that your wheels are oriented correctly?

Yes because we recently switched from labview and strafing worked then but doesn't now.

notmattlythgoe
27-06-2014, 14:16
Yes because we recently switched from labview and strafing worked then but doesn't now.

It looks like you have your parameters out of order when you call the drive method. Try this:

drive.mecanumDrive_Cartesian(driverStick.getX(), driverStick.getY()*-1, rotation, 0);

ccresta1386
27-06-2014, 14:21
Also when we strafe right the wheels spin like:

^ ^
\ /

/ \
v v
and left:

\ /
v v

^ ^
/ \

notmattlythgoe
27-06-2014, 14:25
Also when we strafe right the wheels spin like:

^ ^
\ /

/ \
v v
and left:

\ /
v v

^ ^
/ \

How are your motors numbered?

Ours are always :
1 2
3 4

ccresta1386
27-06-2014, 14:53
How are your motors numbered?

Ours are always :
1 2
3 4

I believe
1 2
3 4
but i will check them at the meeting tonight.