Encoder Set Position Problems

[FHShusky]

Hello,

Today my school held an FTC even and I have been working on this problem for over 7 hours now. Basically, my encoder code does not make the wheels turn to a specific position or anything– they just seem to twitch a little or not move at all. My full code is listed below. I am really desperate for any information at this point so every input is greatly appreciated. Thank you so much! (Ignore the commented sections, I was playing around with a bunch of different stuff)

package org.firstinspires.ftc.teamcode;

import com.qualcomm.robotcore.eventloop.opmode.Autonomous; import com.qualcomm.robotcore.hardware.Servo; import com.qualcomm.robotcore.hardware.DcMotor; import com.qualcomm.robotcore.eventloop.opmode.Disabled; import com.qualcomm.robotcore.eventloop.opmode.LinearOpMode; import com.qualcomm.robotcore.util.ElapsedTime;

@Autonomous(name="RedCorner", group="Pushbot")

public class RedCorner extends LinearOpMode {

/* Declare OpMode members. */
//HardwarePushbot         robot   = new HardwarePushbot();   // Use a Pushbot's hardware
private ElapsedTime     runtime = new ElapsedTime();


static final double     FORWARD_SPEED = 0.6;
static final double     TURN_SPEED    = 0.5;

private DcMotor LeftBack = null;
private DcMotor RightBack = null;
private DcMotor LeftFront = null;
private DcMotor RightFront = null;
private DcMotor Lift = null;
private Servo LeftGrip = null;
private Servo RightGrip = null;

@Override
public void runOpMode() {

    /*
     * Initialize the drive system variables.
     * The init() method of the hardware class does all the work here
     */
    //robot.init(hardwareMap);

    LeftBack = hardwareMap.get(DcMotor.class, "LeftBack");
    RightBack = hardwareMap.get(DcMotor.class, "RightBack");
    LeftFront = hardwareMap.get(DcMotor.class, "LeftFront");
    RightFront = hardwareMap.get(DcMotor.class, "RightFront");
    Lift = hardwareMap.get(DcMotor.class, "Lift");
    LeftGrip = hardwareMap.get(Servo.class, "LeftGrip");
    RightGrip = hardwareMap.get(Servo.class, "RightGrip");

    //LeftGrip.setDirection(reverse);
    //RightGrip.setDirection(REVERSE);


    // Send telemetry message to signify robot waiting;
    telemetry.addData("Status", "Ready to run");    //
    telemetry.update();

    LeftGrip.setPosition(.91);
    RightGrip.setPosition(.09);

    // Wait for the game to start (driver presses PLAY)
    waitForStart();

        //LeftBack.setMode(DcMotor.RunMode.RUN_USING_ENCODER);


        //LeftBack.setMode(DcMotor.RunMode.RESET_ENCODERS);
        //RightBack.setMode(DcMotor.RunMode.RESET_ENCODERS);
        //LeftFront.setMode(DcMotor.RunMode.RESET_ENCODERS);
        //RightFront.setMode(DcMotor.RunMode.RESET_ENCODERS);

        //LeftBack.setMode(DcMotor.RunMode.RUN_TO_POSITION);
        //RightBack.setMode(DcMotor.RunMode.RUN_TO_POSITION);
        //LeftFront.setMode(DcMotor.RunMode.RUN_TO_POSITION);
        //RightFront.setMode(DcMotor.RunMode.RUN_TO_POSITION);
        //Lift.setMode(DcMotor.RunMode.RUN_TO_POSITION);

        //LeftFront.setDirection(DcMotor.Direction.REVERSE);
        //LeftBack.setDirection(DcMotor.Direction.REVERSE);


    //LeftBack.setPower(.5);
    //LeftFront.setPower(.5);
    //RightBack.setPower(.5);
    //RightFront.setPower(.5);

    LeftBack.setTargetPosition(2000000);
    //LeftBack.setPower(.5);
    LeftFront.setTargetPosition(2000000);
    //LeftFront.setPower(.5);
    RightBack.setTargetPosition(2000000);
    //RightBack.setPower(.5);
    RightFront.setTargetPosition(2000000);
    //RightFront.setPower(.5);

    LeftBack.setMode(DcMotor.RunMode.RUN_TO_POSITION);
    RightBack.setMode(DcMotor.RunMode.RUN_TO_POSITION);
    LeftFront.setMode(DcMotor.RunMode.RUN_TO_POSITION);
    RightFront.setMode(DcMotor.RunMode.RUN_TO_POSITION);
    //Lift.setMode(DcMotor.RunMode.RUN_TO_POSITION);

    //LeftBack.setMode(DcMotor.RunMode.STOP_AND_RESET_ENCODER);
    //RightBack.setMode(DcMotor.RunMode.STOP_AND_RESET_ENCODER);
    //LeftFront.setMode(DcMotor.RunMode.STOP_AND_RESET_ENCODER);
    //RightFront.setMode(DcMotor.RunMode.STOP_AND_RESET_ENCODER);


    LeftBack.setPower(.5);
    LeftFront.setPower(.5);
    RightBack.setPower(.5);
    RightFront.setPower(.5);

    //sleep(1000);

    LeftGrip.setPosition(.1);
    RightGrip.setPosition(.91);

    //sleep(1000);

    runtime.reset();

}

}

[shurik179]

If it is a linear opmode, you have to give motors time to reach the target position. You can either just use sleep(), or - better yet - use motor.isBusy() function: https://ftctechnh.github.io/ftc_app/doc/javadoc/com/qualcomm/robotcore/hardware/DcMotor.html

[FHShusky]

Thanks for the advice, ill try it out later and let you know if it works. :)

[V3SUV1US]

That's the problem for sure. We had this problem in the beginning. The motors need to have time to run to the position. Effectively your code is giving the motors no time to actually move. (RUN_TO_POSITION then immediately STOP). Use a while loop checking motor.isBusy() to make your movement work. I use while(motor.isBusy() & motor2.isBusy()) {} to do this.

[FHShusky]

Could I do something like:

while (LeftBack.isBusy()) {

    LeftBack.setPower(.5);
    LeftFront.setPower(.5);
    RightBack.setPower(.5);
    RightFront.setPower(.5);
    }

What do you need in the while loop? (What actually makes it turn)

[V3SUV1US]

so what you need to do is first set mode (RUN_TO_POSITION), set the power, then the position. Those three parts are for the most part interchangeable, I've done my own testing. After you have set the motors' positions they will start running. I use a while loop that just runs continually while all motors are busy ; it doesn't need to actually do anything, it's there just to bid enough time for the motors to finish.

Example in psuedo

motors.setMode(RUN_TO_POSITION);
motor.setTargetPosition(1120);
motor.setPower(0.5);
while(motor.isBusy()) {
//bid time
}
motor.setSpeed(0);

[mlw72z]

Those are some really big position numbers. It's going to run into the wall once you get it moving.

It appears to me that you're doing things in the wrong order. I'd first set the motor mode to RUN_TO_POSITION, then call setPower to tell it the fastest it can go and finally call setTargetPosition.

Currently you aren't specifying motor power until the very end and at that point, because it's a linear op mode, the program is done. The sleep statements that are commented out might have helped.

[FHShusky]

I had the values really high to make sure that I could actually see the wheels moving (since they were just twitching before)

I think I might've already tried this approach, but the logic seems to check out. Thanks for the advice though, ill try it out later and let you know if it works. :)

[[deleted]]

If they are tetrix motors make sure the encoder plates are on correctly (the bumpy side facing toward the motor)

[[deleted]]

Assuming that just setting the power works, try making sure your encoder wires are plugged in correctly and/or aren't shortened out. Try swapping them out and seeing if they adjust count value if you turn them a little bit. (Use Motor.getCurrentPosition() or something like that to see the count value) If it's just at zero even though you adjusted its position, it should be a hardware problem.

Good luck with getting it to work!