Coding problem with motor speed

#1

Hi guys! I’m new to vex this year and I’m unfamiliar to VEXcode. I know some of the basics but not exactly what everything does. Currently, I’m using this code to tile my cube tray:
cubeTilt.spin(vex::directionType::fwd, 0.5, vex::velocityUnits::pct);

however, it keeps accelerating as I continue to hold the button, so I’ve had to dial it down to 0.5 percent to manage it. Does anyone know a way to make the motors just spin at a constant velocity?

#2

we’d have to see the rest of your code. This indicates it always spins at .5%.

#3

This is inside the user control section:

if(cubeTiltFwd) {
cubeTilt.spin(vex::directionType::fwd, 0.5, vex::velocityUnits::pct);
}
else if(cubeTiltRev) {
cubeTilt.spin(vex::directionType::rev, 0.5, vex::velocityUnits::pct);
}
//if neither pressed, then stop
else {
cubeTilt.stop(brakeType(brake));
}

cubeTiltFwd + cubeTileRev are declared as: const auto

#4

Forgive me if I’m wrong, but isn’t .5% very very small? like not moving small.

#5

yes, and it starts out not moving at all, but then keeps speeding up as long as the button is pressed

#6

can you show us your cubeTiltfwd and rev.

#7

const auto cubeTiltFwd = Controller1.ButtonR1.pressing();
const auto cubeTiltRev = Controller1.ButtonR2.pressing();

#8

Change ‘const auto’ to ‘bool’. It definitely sounds like that is the problem and I’m not too sure how ‘const auto’ would work.

#9

Or just type out Controller.ButtonR1.pressing() i don’t see the point in the const auto thing. i see no problems with the rest of your statements.

1 Like
#10

that kind of worked… It seems better but i still feel like its accelerating

#11

you can always use rpm instead of pct. This should* keep the motor at that set rpm. your code is practically identical to the code for my intakes so I’m not sure whats wrong here.

#12

its possible that the load it has to push is changing as it tilts further up (lever advantage)

#13

yes this is possible which is why rpm could be better for same speed control.

#14

I know what the problem is
the velocity makes it increace by .5
if u have this code it should work just fine:
Drivetrain.drive(fwd, (Controller1.Axis3.value() + Controller1.Axis3.value())/2, velocityUnits::pct);

Drivetrain.drive(reverse, (Controller1.Axis1.value() - Controller1.Axis1.value())/2, velocityUnits::pct);

#15

The problem was a broken motor encoder. The motor couldn’t tell how fast it was going and automatically went from whatever speed we told it to 100%. Fixed by replacing the motor. Thanks, all!