Hey, my team’s robot seems to have more friction on the right side than the left. It slants sideways when going at high speeds in driving and autonomous which makes testing out PID difficult. We don’t know how to fix this. I’ve attached pictures, the first two are for the left side, the last two for the right side.
What is holding the outer rail to the rest of the robot besides the one obviously visible standoff? You want at least three points of connection to make that solid. Otherwise, you’ll be chasing little problems forever.
11 Likes
It seems like your drive doesnt have enough sturdy connection points to the outer bar
It looks like there is not enough space between the chain and wheels. I think the chain is actually rubbing on the omni wheel. Also your rail is bent near the omni wheel since the omni is wider than the non-omni wheel. I would widen the space between the drive plates by 1/4", add a spacer between the wheel and sprocket.
Once you have that straightened out, put your robot up on blocks so the wheels are off the ground. Set the drive to full speed with code or the joystick. Use the dashboard for the motor to monitor current draw on each side of the robot. If one side is drawing more current, then that side still has more friction.
9 Likes
Thank you for posting detailed pictures of your drive, this helps a lot with finding the problem.
The obvious problem here is that your outer drive rail channel appears to be bent quite noticeably. That could just be from the way the pictures were taken, but may not. If that c-channel is bent, you should replace that for a straight one. Additionally, you need to have multiple attachment points for your outer drive channel- right now, it appears that the only ones are 2 standoffs. While standoffs are great for maintaining attachments in your drive in places where you don’t have room for a full brace, they shouldn’t be the only thing holding your drive together. It appears that the 5-wide is a perfect place to attach your channels to, you should do that with at least 2 screws. You can also attach your outer brace to the angle piece- while that will not provide as much support as a c-channel, it will still help a lot.
You will also probably want to put another brace on the bottom, it will help some with stability.
Also, make sure that you have bearings on all sides, and that they are aligned with the holes in the c-channel. You should also not have any metal-on-metal contact, make sure that you have plastic spacers or washers between shaft collars and metal.
That should fix most of the big problems. Additionally, putting more motors on your drive ( it appears you only have 2) will go a long way to making the effects of friction less noticeable, as you have more motor power to fight against friction.
Also, +1 to all of these.
If you want to go down the rabbit hole of proper build quality and construction, here are some good resources to start you off with:
Designing a Quality Drive
Designing Another Quality Drive
Hope these help!
6 Likes
Axles are not structural components.
2 Likes
It looks like your wheel is rubbing on the c channel
1 Like