pic: 1736 Robot Casserole's U~Slide Drive



We’re developing a unique slide drive for Recycle Rush. We’ve taken a typical H-drive and moved the strafing wheel to be inline with the front of the robot to reduce issues while driving over the scoring platform.

This wheel is on a coil spring suspension to improve strafing - something that was learned after initial testing. Our code will use a gyro in the loop to prevent unwanted robot rotation while strafing.

Here’s a video of the drivetrain in action.
http://youtu.be/kM0eVQPa9JU
At 1:20, we begin using the gyro to correct the robot’s rotation.

What are the green inserts on the rpborio and where did you get them?

It looks like something similar to Wildstang’s Cable magic. My guess, whatever it is, custom designed or found on the internet, it looks to be a 3D printed part.

http://wildstang.org/blog/?p=472

Yep, Wildstang’s Cable Magic. Thanks 111 :cool:

Great to see it in use!

Please check our blog tomorrow. I will be posting up the CAD files for the small/short version for the analog and relay ports.

It looked very similar I just couldn’t tell if it was the same or not.

What were some of the pros and cons of the chassis, not referring to recycle rush, but as a sort of H drive chassis how did it do? I’m exploring different designs for an H drive chassis and noticed yours and though it would be a quick and easy solution to an H drive

Do you have CAD or pictures of how you accomplished your spring suspension? I was designing an H-drive this summer, and I couldn’t find any pictures of such a suspension.

Looks like you’re asymmetrically powering only the upper left (in the picture) and the lower right wheel. How’s that working out? I’ve never used omniwheels before - do you have to power all the wheels (like a WCD) or not?

There are two other belt runs obscured by the flanges on the chassis, all four wheels are powered.

You don’t have to power every wheel on a drivetrain, but you’re wasting tractive force by not doing so. It’s a very good idea to do so, particularly when the field isn’t flat.

Nope, they’re powering all of them. The frame hides the near-side belt on both sides.

Omnis being all/not all powered depends on the exact type of drive. If they’re in tank configuration, they don’t all need power. But if you’re doing something funny–say, omni-directional movement–you’ll need 'em all powered (in general). And, in general, you want all your wheels that are on the ground powered (unless you specifically don’t).

I see it now. Thanks!

+1. I’m thinking about doing something with omniwheels right now in the preseason, and it’ll be great to see some examples of spring suspension.

What is the vertical travel at the wheel axle? Would it let you go onto the scoring platform at an angle without banging things up too badly?

We’re doing a similar project, but we’re mounting our strafe wheel pneumatically, so we can lift it when we don’t need to strafe or when we need to go over an obstruction. Pics to follow.

Travel was only around an 1/8 or so after we dialed in our downforce. Since the wheel was offset towards one end, we still had control of the robot even if the straffe wheel was holding the other two off the ground. I don’t think our drivetrain held us back really even when we were forced to go back to open loop due to gyro issues.

I like the pneumatic approach better than adjustable spring. We’d lose a lot of pushing power if we used the spring approach in a year with defense as it took more downforce on the straffe wheel than was originally expected for good straffing performance.

I also like how the Robowranglers did their double center wheel in 2014. I we do h-drive again, I’d strongly consider this approach.

Pros:

  1. Easy way to add h-drive to kit.
  2. U approach straffed well even with a heavy load of totes on the straffe wheel side on robot.
  3. Clearance to cross bump easily
  4. Ajustable spring for allowed us to dial in quickly during a regional.

Cons:

  1. Reduced pushing capability due to spring approach to load center wheel in games of defense.
  2. Limited travel of center wheel due to using kit plates for 5th wheel
  3. Heavy
  4. Needed gyro to help compensate for tendacy to turn during straffing.