Are the ramps the 'Swerve defeater'

FIRST General Forum
53

I will continue to link this thread wherever relevant to the ends of the Earth.

3 Likes
54

The bumpers can also be 4.5" for another 1/2" of clearance.

2 Likes
55

To be clear, the ramp in that picture is at the 11deg situation, correct? Not the balanced situation?

1 Like
56

has anyone tested swerve on a ramp yet? currious if there are some early results

1 Like
57

I feel like it’s worth backing up to ask what the skeptics think would be the issue with a swerve drive climbing the ramp. In particular, what disadvantages do you imagine it could have compared to a WCD, for instance? At a minimum, you can lock the wheels to point the same direction and get the same effect as a WCD with four traction wheels engaged with the floor. The breakover angle is worse with no wheels near the center of the frame, but in normal operation that shouldn’t come into play. With the greater ground clearance that swerve typically allows, the approach and departure angles should actually be better than basically any other standard drivetrain.

Exactly what situation is someone imagining in which a swerve is less suited to navigate the charge station than a comparable alternative drivetrain?

4 Likes
58

The diagram is only correct if the robot enters the ramp while it’s already down. If it’s not down yet, the grey line is at a 30+ degree angle, not 11.

59

The real question is how swerve would be affected by the broken cubes.

60

Our swerve driving up a static charge station (35 degrees ramp)

9 Likes
61

Yes, 11 deg

1 Like
62

I am not sure what tread is best for polycarbonate, but our team plans to do some prototyping on this very topic.

63

We tested MKi4’s going up 15 degrees on top of lexan today.

64

well, once you start to move up the ramp, it will almost immediately tip towards you, so I think this drawing is still representative. Only difficult part would be when you have teammates on the platform already, and then some momentum might be necessary. However from tests that some teams have completed, it looks like it won’t be much of a problem at all

65

Here’s the Ri3D Redux testing with MK4i swerve both with and without bumpers on the charging station: Charging Station Swerve Drive Testing and Construction Ri3D Redux 2023 - YouTube

5 Likes
66

2010 Robonauts reveal vibes

1 Like
67

interesting that they had so much trouble, it seemed like the bumpers didn’t affect it at all either, it was all the frame height. I wonder why this results was so different from 3075’s test. Possible that RI3D redux’s model has too much of a lip (on the lead-in ramp), which would explain why it caught weirdly in one of their runs. From looking at the field drawings, there should be almost no lip whatsoever

2 Likes
68

We were fortunate enough to have a team ramp (plywood) ready day 1. We found that the surface REALLY needs to be polycarbonate to work properly, otherwise the aluminum frame or bumpers will catch on the surface and push the ramp up rather than down.

Swerve is OK - balancing, on the other hand, is going to be a challenge!

(we have MK4i’s with falcons in low ground clearance config, FWIW)

1 Like
69

they also seem to have a lot of friction in their setup. It doesn’t return to flat by itself. someone has to push it back down.

1 Like
70

We used the AndyMark mecanums in 2016 and had no problem with the ramp. Not that I would use us and Bomb Squad in the same sentence. :slight_smile:

71

At first I said simply no and I still think so but there is definitely a desgin challenge to using sweve with the charging station.

72

also the robot wasn’t weighted down. you should get more traction that way.