Need Help Slowing Down Drive Motors

I am trying to slow down the motors in labview. I am using the default tank drive. I was given a screen shot of a Mecanum drive slowdown but didn’t work, Help please.

What specifically do you mean?

  1. Do you want to reduce the maximum speed that a drive motor can be driven, and scale the lower speeds down proportionally? In this case, a simple multiplier of the motor input values by a number between 0 and 1 will do.
  2. Do you want to reduce the motor speed at the low end but allow full speed at the high end? In this case, multiply the motor input value by its absolute value.
  3. Do you want to have two or more modes (slow and fast) that you can switch back and forth? In this case, you can use the first case, but make the multiplier dependent on another control.
  4. Something else??

The answer depends on why you want to slow the motors down:

  • because the joystick gain is too high at low levels making fine motion control difficult?

  • because the robot accelerates/decelerates too quickly, causing the load the robot is carrying to fall over?

  • because you want to limit top speed because the driver can’t control the robot properly at high speeds?

The more info you provide about what you are trying to do and why you are trying to do it, the more likely you will get useful answers.

EDIT: GeeTwo beat me to it, but didn’t mention voltage ramping (to limit acceleration). Also no mention of changing gearing, which is probably the correct solution (albeit more difficult).

If you simply want to reduce your motor speeds, take the value from your joystick, and either divide by a number, such as 2, or multiply by a decimal, such as .5, for half speed. There are various other ways to do this but for simplicity’s sake, this will do the trick.

the joystick is very sensitive just barely moving it make it go crazy fast. Can you attach a pic how to do this? (new to labview)

Here are a couple of examples:

or maybe try some different joystick response curves.

If it’s at all possible, you should change the gearing.

This sounds like you may be multiplying the joystick value, or perhaps you’re using a spike relay instead of a motor controller (Talon, Jaguar, Victor)?

Seeing your drive system code would probably help.