# Programming a reverse double 4 bar lift

Hello,
I recently decided to take the role of programmer on my team and I need some help with programming a reverse double 4 bar lift. I have searched Google and YouTube far and wide, but still can find any help. I just have no clue where to start on programming because the reverse double 4 bar is a little complex. Any help would be greatly appreciated!
Thanks,
James

@SVTHS James
There are numerous ways to program a DR4B. It depends on what you want it to do, and how you have built it. A few questions to consider before someone can really help you:

• Are the top and bottom section mechanically linked, or independent?
• Do you have any sensors?
-Do you want to use a joystick or a button to control the lift?
-Is this for autonomous or driver control?
-do you want to move the lift manually, or just press one button and have the lift go to that height?

-A button would control up and a different button would control down.
-Both autonomous and driver control.
-Manually lift it.

The basic idea is just to set the two motors opposite to each other (one could be “reversed”) at the same speed. One way will go up, the other will go down. Try it out with the joystick first, using one button to make it go up by setting both motors from it, one positive and one negative, and using another button to make it go down.

Once you’ve got that, if you want to know how far it goes for autonomous stuff, commonly a potentiometer is useful. Measure the angle you’ve rotated one of the angled pieces from a vertical piece. Once you know this angle, it’s some trigonometry and addition to know what height it reaches. You might code things in different ways at that point, such as recording an array of angles that go with different heights of stacks. Even better are two potentiometers to make sure it stays even.

If you only have a specific spot, like a lowest point, you could use a limit switch or similar to tell you when you’ve reached the bottom.