Brakes

[Joe_Widen]

You are most definately correct. They work very nicely, well once we switched from 5:1 to 10:1. The only way to get us to move is by hitting us really hard.

[amos229]

All i can say is surface area and 60 tread.

[ahecht]

Originally Posted by Joe_Widen

You are most definately correct. They work very nicely, well once we switched from 5:1 to 10:1. The only way to get us to move is by hitting us really hard.

The only problem with that is that you are going to lose 30%-40% of your power due to the massive inefficiency of the worm and worm gear (and a more efficient worm gear would be backdrivable).

[ScoutingNerd175]

Well, it's nice to know that some people do actually have breaks. I believe we had one last year, although I knew a lot less about the robot last year (I don't think I could have answered my own scouting sheet!) but we don't have them this year because of weight. (we came in a bit over when we first weighed in).

But people give me the weirdest looks when I ask them if they have breaks while pit scouting. So thanks for proving that it's not that odd of a question!

[PEKMAN]

Team 293 is using brakes based off of 25's design:
A servo sticks a pin into a milled out gear in the gearbox.

For the ammount that they weigh, the benefit is huge. If the brakes are on, the wheels don't turn.

The only problem is that before we got the settings just right, we snapped several servo horns.

[Bob22341]

Originally Posted by pakrat

Does your robot have brakes? If so, how well do they work? How did you design them and how did you implement them?

Our robot had brakes...
They worked really well...

Actually our robot was able to push other robots around, so we just drove into other robots and pushed them backwards.

[pakrat]

does anyone have any pictures of the BMS brakes?? They sound very useful. I know that my team wouldnt really benefit that much because we dont have the room for more servos, plus we have a holonomic drive, but it would be nice to see what some people think is impossible for a FIRST robot.

[George A.]

It's not our robot but I think it was team 486 The Positronic Panthers (forgive me if the team/number is incorrect) has a nice bumper/brake system. They would be a "Crash Shell" around their robot that once another robot pushed into it the pushers force would be nutralized.

I know there's a video out there that shows it, and it was really nice, but since the rule changes happened this year, those bumper/brakes weren't allowed.

[nuggetsyl]

Originally Posted by pakrat

does anyone have any pictures of the BMS brakes?? They sound very useful. I know that my team wouldnt really benefit that much because we dont have the room for more servos, plus we have a holonomic drive, but it would be nice to see what some people think is impossible for a FIRST robot.

If we get into the book you will have the cad of it. but since we are not going to know any time soon see our pits at nationals.
shaun

[UlTiMaTeP]

179 Does . They use a piston with waffle tread on the bottom

[Jay TenBrink]

We have used dynamic braking for the past 3 years. There is a potentiometer mounted on each of the two final drive output shafts of our 4 wheel drive skid steer. When another robot pushes against ours the wheels begin to turn. When this movement is detected, the controller applies power to those wheels in the opposite direction to oppose the movement. The more needed, the more is applied. This gives us enough braking to lock the wheels. If another robot has the power and traction to move us with our wheels skidding, then they will win the pushing match.

In 2002 we had pneumatically applied brakes that worked great. There were two flat pads about the size of a playing card covered with rubber belting. The back of the robot and the movable goal we were latched on to was lifted off the carpet when these were applied. Nobody was able to move us that year.

Jay

[UlTiMaTeP]

Now with the presence of, off the shelf 2 and 3 speed tranny's and 4 and 6 cim's on a drive train, it is pretty hard to not be pushed around.

[Aren_Hill]

on thurday in atlanta we (1625) put grippy tires on the back and a "foot" that rotated down in the front lifting up our omniwheels making us practically unpushable but a few team found this out and moved us by ramming Our major weakness before nationals was getting pushed while shooting and made our accuracy terrible so when we added the foot thats what made us the #1 seed so basically sticky stuff rules

[Pavan Dave]

I liked 1625's breaking meathod because it was simple and effective... One of our teammates suggested something similar but it got vetoed and than his hopes jumped when he saw a robot seeded #1 all because of something he had thought of.

I wanted that on our robot after i saw its effectiveness because our robot's best defencive was its Agility.

Pavan

[Matt Krass]

Originally Posted by Joe_Widen

Nope, good guess though.

Hint, its built in to the drive.

Is it like our software brake?
The code monitors the encoders and whenever the joysticks fall within a deadband, it goes to hell and high water, and current limits to maintain those specific counts, so if we get pushed, it fights as hard as it can.

Mark McLeod can illuminate more on the subject.