I’d be interested in some quick comments on your team’s thoughts on including bumpers. While the extra weight can help make the bot a bit heftier, some on our team are concerned that they will decrease top speed significantly. Thoughts?
my team is useing the bumber for a number of reasons
1.extra weight
2.larger parimeter:less room to block the shot ball before it gets to five feet
3.protection to our robot
what about the disadvantage of a larger perameter? it would be harder to fit 3 robots onto the ramp
i am just curious if in the past you have ever included the weight of your robot in your drive calculations?
i am going to wait to decided about the bumpers till the rest of the bot design is nailed down
the ramp is 11’ wide…this gives every robot 44" of space.
if each robot is lined up long side - long side - long side and each has the 3" bumpers on each side…i think they’ll still fit.
of course, if you grow to the whole cube and become 60"…then it’s another problem.
To be considered for the “ramp” points your robot does not have to be on the platform itself but just completly off the floor and supported by the ramp and or platform.
Down side with the pool noodle thing is it can get ripped up real easily. But a backup spare bumper maybe help.
Generally speaking, a little extra weight won’t affect your top speed, which is influenced more by the power of your drive system and friction. These 'bots don’t go fast enough to influenced by air resistance. Where weight can really hurt is in acceleration and energy efficiency. A robot that weighs an extra 10-12 pounds will go just as fast, it will just accelerate slightly slower and use up more energy from the battery. Given all that, increasing the weight of your 'bot by 8-10% probably won’t have a noticeable real-world effect.
The bumpers will provide real protection to your wheels and chassis.
The bumpers will reduce your maximum approach angle. This Website on off-road vehicle terminology explains approach angle and several other terms that will come in handy to if you are building a ramp climber. Here are a few key items from this site:
Approach Angle: This is the angle at which an obstacle may be approached before the vehicle will touch it. The mounting of Nudge Bars or similar fittings can impair this angle. It is also known as the attack angle.
Departure Angle: This is the angle at which you can leave an obstacle. It can also be hindered by the fitting of bumpers, tow bars etc.
Ramp Angle: This is the most difficult angle to explain. It is the angle of an obstacle that will clear under the belly of the vehicle.
Roll Over Angle: This is self-explanatory and is the side angle that the vehicle will tilt over, before rolling.
I am normally opposed to bumpers, however after looking at the starting grid with all six robots reletively close and each wanting to get to a different place on the field as fast as possible during atonomous, I would expect A LOT of hard collisions in the middle of the field. Bumpers might be a good thing this year. I wouldn’t be too concerned about them decreasing top speed that much.
ERic
I remember reading the rules about the bumpers but does anyone know if the rules specifically state that we have to have bumpers on all 4 sides? We generally have cantilevered wheels so putting bumpers over those is difficult.
Using bumpers as bumpers is going to be a good think.
But… Ff = N X Uf
Bumpers increase that Normal force by 15 lbs…
Little more grip when pushing?
Little more force required to turn (tank style at least)?
Lots to think about…
No, the rules do not require bumpers on all four sides. In fact, if you watch the kick-off broadcast closely, during the game demonstration a few of the “sample robots” (the big red and blue boxes) only have bumpers on three sides.
-dave
Is it legal to run into other robots only if you have bumpers? I don’t quite understand that rule completely.
Read it again. Incidental contact is fine, AS LONG AS it occurs in the “bumper zone”. High speed ramming is taboo, as is contact that is not either incidental or inside the bumper zone. If you do not have a bumper, the bumper zone is still on your robot, and legal contact can only occur there. If you do not have a bumper, you can still run into other robots.
One of our engineers figures you need at least 4" of ground clearance to not high side your robot on the ramp. If this is true, than how can you have your bumpers 2.5" above the ground and still get up the ramp? Even if you have you bumpers at the highest allowable point at 3.5" (5" of bumper down from 8.5" max.).
I can also see allot of contact above the bumper zone and the 5 point penalty :ahh:
You might want to consider 6 wheels. Our base is 2" off the ground and we clear the top of the ramp by about 1/4". Just a thought.
~Kirk
how far apart do you have your wheels?
A ramp contacts an arc starting at the base of your front wheel, reaching some peak(dependent on the distance between your wheels and the angle of the ramp) and then going back down towards the rear wheel. 6 wheels, this works out just between the wheels which is why it removes a large portion of the raised chassis. The bumpers In theory I suppose could follow this arc staying between the 2 1/2" and the 8 1/2" marks. As for the front and the back of your robot, 2.5" is probably high enough but you should check it out with your own design. Hope that helps.
My preliminary cut at it says the 2.5 or even the 3.5 inch height to the bottom of the bumper limits the size and placement of the front wheel(s). It favors robots with small wheels. If we put bumpers on the front of the robot we expect to build, it will drag slightly going up the ramp.
We have 6" wheels mounted flush with the end of the frame front and back with the base running the long way. So we have 10" between wheels. Just something to think about.
Good luck
~Kirk