Programming or Building Problem

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Just wondering if anyone has any suggestions? Our robot will not lift the arm portion we have rubber bands on the inside the arm. Our programmer has tried everything torque, speed, and velocity.

Well one of your motors drives a 1:1 where as the other is geared for torque which may be keeping you from lifting. The other problem could be your code; the motors wouldn’t really lift if they run the opposite direction than they are supposed to be turning. Also, put more rubberbands on the outside, loop them onto each other so there is more tension per band but put more bands and in more locations. Check your code and fix the torque issues first though.

Edit: The reason the motors without a ratio aren’t helping is because they add considerable weight but very little relative torque. Your lift would be a monster if all 4 motors were geared like the bottom 2, but since they aren’t the top is adding more weight than torque and is spinning faster than the bottom, hurting the overall system.


I really appreciate this. Unfortunately since this design is fairly new we didn’t have all the parts we needed. The plan was to gear the top like the bottom but our parts shipment hasn’t come yet.

In that case, I would highly suggest detaching the top two motors. Our lift only has two motors and functions fine. If they can’t be fixed relatively quick, I would get rid of them as they are only hurting your bot.

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Do you think if we jacked it up a little bit from the bottom that it would start? It works just fine without the 2 motors and claw if we detach them. We are trying to figure out a lighter claw design.

Lmao use more rubber bands. Our lift has 2-4 rubberbands on 6 different points on the lift and I believe each is double or triple looped on itself.

Can you manipulate the lift manually (using care) with the power off (ideally with all 4 motors removed)? Does it take a lot of effort?

As the other poster has mentioned, many teams have had success building 2 motor lifts. 4 motors seems overkill.

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I understand what both of you are saying when we first attached the claw it instantly would not lift so we thought adding the two motors would be the best option. It lifts beautifully without the claw and top two motors. Any claw suggestions though?

try reversing the motors in code if the life kinda twitches then they are working against each other

Our programmer is confused on the coding part could you send a example? We are new to robotics.

If you are in vexcode then go in the config and slide it to reverse. If you post your code we can help

Here is our program.

This is vexcode right?

VEX coding system is what im using

Im the programmer for the team

At the top right there is an icon that looks like a V5 port
Click it and you should get a menu with all of your motors and configs
Select the motors for the lift and drag the slider across to reverse it.

We did get everything to work. The only thing that we need help with now is the getting a cord long enough to reach the claw. We were thinking of making a custom cord. Does anyone know or have any suggestions on how to make them?

Literally the easiest way is to follow the directions on the back of the wiring tool Vex provides. When making the wire, one tip would be to keep it as straight as possible before putting the heads on as problems arise when the wire bends and one wire gets pulled a little too far back into the case and doesn’t connect to the head. Also, cut more wire than needed as something small can force you to create an entirely new wire. The easiest way to know how much wire you need is take some tape and string. Tape one end of it to the motor, and run it like you would the wire, tapping it to different parts to keep it there. After you run it to the brain, keep some extra, cut it, and then use that to get your wire length.

Friction, friction friction. Seeing your lift really does scream friction to me. If you have high strength on everything then you should take precautions to lubricate the axles to ensure that everything moves correctly. Looking at your code you seem to have a random open bracket that does absolutely nothing (It’s above the task sleep). Please make sure to check the brackets and ensure they are where they are supposed to be. In addition, do not make the task sleep for 100 miliseconds, you will make your driver suffer with extremely bad latency. I would suggest a maximum time of only 10 miliseconds for sleeping. Anything higher than that you are destroying the driver’s capabilities.


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