Articulating chassis???

Anybody thought about an articulating chassis? By that I mean one that bends in the middle so It goes over the bump without leaving the ground?
Any thoughts?
Bruce

it might be a good idea as long as the bumpers dont move… also it just seems like it might be more work then its worth

I’d like to see a sketch of what you have in mind.

Yeah, we though about it for a little while until we realized that the bumpers can’t articulate. In my opinion, it would be pretty difficult and complicated to implement. But if you find a way to do it, I’m sure it would be pretty cool.

It can be done, but would it redefine where the bumper zone on your robot is located? If the back end, for example, drops below the front end (the front end is on top of the bump while the back end is on the ramp), the bumpers, while still between 10" and 16" above where the front wheels contact the top of the bump, are now possibly more than 16" above where the back wheels contact the ramp.

Thoughts?

From page 4, section 8 The Robot:

FRAME PERIMETER – the polygon defined by the outer-most set of exterior vertices on the ROBOT (without the BUMPERS attached) that are within the BUMPER ZONE. To determine the FRAME PERIMETER, wrap a piece of string around the ROBOT at the level of the BUMPER ZONE - the string
describes this polygon.

And <R11>

The FRAME
PERIMETER must be comprised of fixed, non-articulated structural elements of the ROBOT. The FRAME PERIMETER must remain a fixed, unchanging polygon throughout the MATCH.

So a fully articulating chassis is not allowed - it would change the polygon that defines your FRAME PERIMETER whenever it bends.

You could have a suspension system with your wheels to accomplish the same thing, however.

we threw this idea around a bit, and we so far see the most problem with the bumpers:
if the robot articulates in any way, even if it has a fixed frame to hold the bumpers, it would change the height of the bumpers and if they leave the bumper zone, that’s illegal.

you could perhaps design a system to hold the bumpers at the correct height at all times, but I’m thinking that’s overkill considering that most “normal” robots should be fine just driving into bump slowly to get over it…

Nope, nobody thought about that before. Except these folks:

What about keeping the frame fixed but putting the wheels on some sort of gimble to keep in contact with the floor/hump?? Take a look the spirit and opportunity robots and see how that suspension floats over the terrain…

BC

That could be a good question for the GDC. The problem comes with the definition of the bumper zone, from page 3 in section 8 The Robot:

the volume contained between two virtual horizontal planes, ten inches above the floor and sixteen inches above the floor.

and <R07>A:

BUMPERS must provide complete protection of the entire FRAME PERIMETER of the ROBOT (i.e. BUMPERS must wrap entirely around the ROBOT). The BUMPERS must be located entirely within the BUMPER ZONE when the ROBOT is standing normally on a flat floor, and must remain there (i.e. the BUMPERS must not be articulated or designed to move outside of the BUMPER ZONE).

So, for example, if you have a 6 wheel robot with front and back wheels fixed, but a passive suspension on the middle wheel, you might me fine - when you’re starting up the incline (or finishing coming down) the suspension would push the middle wheel down to maintain contact - at the top, it would let the middle wheel ride up to give better stability/contact - but the key is that, at all times on level ground the bumper remains within the bumper zone. That’s pretty easy to prove with a passive suspension, and may be allowed

What if the suspension is active?In that case, you may have an issue, as the suspension could push out, increasing the height of the bumpers outside of the bumper zone.

What if the suspension is on all wheels? Then you might also have a problem, as any adjustment could cause your bumpers to leave the bumper zone.

I would recommend asking the GDC about the legality of suspension on wheels and how that comes into affect with regards to traveling over the bump and the bumper zone before getting too far in your design process.

suspension would not change whether the bumpers are in the bumper zone or not, because any adjustments are likely going to be small, and when they are absorbing shock, the drive plane remains the same. although, i’d ask the GDC, just to be sure

Hi,

We are from team 3089.

We are currently debating whether the following mechanical structure of the chassis and bumper is legal. The chassis is divided to two parts that are joined together allowing it to change its geometrical shape (as shown in the pictures) when going over the bumps (articulating chassis). Above the lower chassis, is a chassis of a larger perimeter that has a solid structure and will consist of the bumpers. As stated in rule <R11> the chassis itself does not change it’s shape and when the robot moves on the flat surface it is parallel to the ground.
But when the robot will go over the Bumps, the chassis changes it’s angle compared to the ground and the robot.
Regarding rule <R07> A, the upper chassis is designed so that the bumper will not go out of the bumper zone, and won’t move or deform while on flat ground.

Thanks, every comment is useful!