Another Programming Issue

VEX V5 General Discussion Technical Discussion
1

Hey guys, sorry to bother again. Right now I am stuck in the middle of a dilemma where I cannot figure out how to let my arm position function keep my arm at a certain height during certain segments of my auton.

Here are the two functions, and I am currently trying to get it so that when my arm is up, it stays at a set height of 700 ticks of the IME, and when I want my arm down, I can just set my height variable to 0.

void auton_3(){						//Undefined
	SensorValue(claw) = 0;							//Unfold
	wait1Msec(1000);
	a_drive('f');												//forward to pick up stars
	wait1Msec(1000);
	stop();
	SensorValue(claw) = 1;							//grab stars
	a_drive('b');												//drive back
	wait1Msec(800);
	stop();
	a_drive('>');												//turn left
	wait1Msec(1000);
	stop();
	a_drive('u');												//lift arm up
	wait1Msec(1500);
	stop();
	a_drive('f');												//drive forward
	wait1Msec(1500);
	stop();
	SensorValue(claw) = 0; 							//drop stars
	a_drive('<'); 											//turn right
	wait1Msec(400);
	stop();
	a_drive('d'); 											//arm down
	wait1Msec(1000);
	stop();
	a_drive('f');											 //drive forward
	wait1Msec(500);
	stop();
	SensorValue(claw) = 1; 							//grab cube
	a_drive('<');												//turn right
	wait1Msec(200);
	stop();
	a_drive('b');												//drive back
	wait1Msec(500);
	stop();
	a_drive('u');												//lift up
	wait1Msec(1500);
	stop();
	SensorValue(claw) = 0;							//release cube
}

	void arm_pos(int height){
			if(SensorValue[IME] = height{
				motor(lift1) = 0;
				motor(lift2) = 0;
				motor(lift3) = 0;
			}
			else if(SensorValue[IME] < height{
				motor(lift1) = 127;
				motor(lift2) = 127;
				motor(lift3) = 127;
			}
			else if(SensorValue[IME] > height{
					motor(lift1) = -127;
					motor(lift2) = -127;
					motor(lift3) = -127;
			}
	}

Note: In the beginning before auton, I have my IME set to read 0 before anything occurs so that down is 0 ticks, and up is a set value of 700ish ticks.

2

Sorry that the comments are so messed up, just let me know if you have any questions on what any part is supposed to do. @Cody @jpearman

If I could get help tonight, that would be best, my state tournament is in a couple of days, and I need this auton to work flawlessly.

3

Would one way to do this is by using multitasking, or are you not able to multitask during auton. If so, how would I implement this, and how would I carry the height values over to the other task from my current task. Would it be as simple as just giving a new value to the height function, or would I have to engineer a way to carry that variable over.

By the way, I figured out that I would be able to use a potentiometer in my arm_pos function and it would just replace the IME variable already in the statement.

4

Yes, it sounds like you want to create an arm control task using PID, or PD or P control. Search the web/forum for proportional motor control, or PID control - there are many examples.

5

I understand how the P loop works, however I am having difficulty on how to implement it into my auton.

6

Try this forum post:
[https://vexforum.com/t/simple-p-controller-for-arm-position/23699/1)