launch Motors help

VEX Robotics Competition Discussion VRC > Nothing But Net (15/16)
#1

My team is trying to program the motors for our launcher. its a rubber band slingshot-ish launcher. we have 2 motors giving it power. so our problem is:

  1. the motors only work on a joystick (should be a trigger)
  2. our launcher moves slow. (can we overclock it?)

any advice would be helpful. thanks!

#2

Check to make sure your programming is correct.

If you plan on competing, do NOT modify your motors, and I still wouldn’t suggest it anyways.

Check how much friction is in your system, and lower your torque if you can.

#3

Hey, okay firstly you should check your programming. If you need any help making the programming for your robot feel free to PM me or post a question on the forums.

Secondly, to improve speed you shouldn’t modify your motors in any way, unless your changing the gears to a high speed or turbo kit. You are going to want to reduce friction to speed up your slingshot and maybe even add extra motors.

#4

Im just wondering if its possible to** code the motors beyond 127**. We have two 393 motors on each side of a medium-large gear. There is the smallest gear on each motor. (it looks like this but with another small gear on the other side of the larger gear)

#5

You can code motors beyond 127, but it will just read that as 127 (So for example, motor=150 would set the motor to 127).

I think they made it like this because it would be annoying to get an error every two seconds and crash :smiley:

Changing to turbo and high speed would just change internal gear configuration, meaning you would set to 127 in the program to achieve each configuration’s maximum speed.

#6

Another way to increase speed would be to increase your gear ratio (from 1:5 to, say, 1:3), if you don’t need all of the torque your motors put out. As for the button control, I’m assuming you are using RobotC, as I have had similar issues in the past. You can use a ternary statement. Here is the RobotC documentation on how to use it: http://www.robotc.net/wikiarchive/Tertiary_operators
Basically, ternary statements are a way to abbreviate an if-else block. They can also be nested to abbreviate an if-else if-else block, but that is generally not very readable, at least to me.

#7

I would suggest having a higher gear ratio and not running the motors at full speed if all possible. We’ve been running ours at full speed and have been snapping the teeth on the internal gears like there’s no tomorrow. Mind you, our motors have gone through quite a lot.
Dependent on your strategy, see what gear ratio you need, and don’t overdo it, or you’ll be putting unneeded stress on your motors.
Let me know if you have any other questions.

#8

Arguably you could increase the speed of the motor using several nefarious tactics, but honestly don’t because, you might break your motor, and its not legal (at ALL).

Remember that 127 just represents the top speed that the motor can move. Your robot just interprets anything above 127 as 127. So coding 99999999999 will still only make the motor move at 127 speed! :eek:

If you change the gears to high speed gears ( presumably that’s not what you have at the moment ) then its just like putting extra external gears on the motors. Remember, it will reduce the torque! and whether that will be a problem for you will depend on the tension that you have the motors under.

In terms of Button Control…

Basically, ternary statements are a way to abbreviate an if-else block. They can also be nested to abbreviate an if-else if-else block, but that is generally not very readable, at least to me.

Ternary statements are not really needed, a simple if-else statement will do, something like this: (note: I don’t currently have a robot or a copy of robotc to text this with ):


while(true)
{
    if(vexRT[ButtonForGoingForward] == 1)
    {
         motor[motors] = 127;
    }
    else if(vexRT[ButtonForGoingBackwards] ==1)
    {
         motor[motors] = -127;
    }
    else
    {
          motor[motors] = 0;
    }
}

If you are using easyC then the fundamentals are the same, [this video is quite helpful

The gear ratio just refers to the ratio of turns two (or more) gears make. So a 1:1 gear ratio means that the if one gear makes a full rotation, anthother other gear does as well.](“https://www.youtube.com/watch?v=DQWJ1FUxK7g”)

#9