The Chassis Project.

[Cory]

I am one of those people that will never be convinced that plywood is an acceptable building material for any teams that have an alternative. Plywood is not a very sturdy base to be mouting big, heavy objects on, such as arms, which would be moving back and forth, while flexing the plywood. If you have metal, use it! It is really not that hard to work with and offers a much stronger and more secure surface for mounting stuff.

My list:

Weight: using 10/10 from 80/20 last year we made a frame that weighed less than 25 lbs. It was a simple 30"x36" with a "top deck" that was 4" taller than the bottom on it. With all motors, electronics, and battery mounted, we had a working robot that weighed less than 80 lbs. You hear about these teams that are bending massive pieces of aluminum extrusion. If you look deeper, you will see that these are teams who have tons of speed, but perhaps not so much power. They will ram into an opponent at top speed to try and dislodge them, causing bends to occur. We built a robot that had the power to move other robots just by pushing them, no ramming involved, which meant that 10/10 worked very well for us, and kept weight low (In fact, too low).

I would have to say that a four wheel drive chassis is definitely the easiest to construct for the benefits you gain. However, if you are geared for high speed, and you arent using the terrible wheels FIRST supplies, you may have trouble turning. In this case, I also like the 6 wheel design with the middle set of wheels a tad bit lower than the other 4, giving the robot a pivot to turn about. If omni wheels, or the really slick wheelchair wheels are used in this situation, turning becomes even easier.

For plenty of attachment points, just make a basic rectangular chassis. If a team wasnt going to have many attachments, you could just build onto the bottom. If you wanted to add many/larger mechanisms, you could place the motors, wiring, battery, and other random stuff in the very bottom to get a nice low center of gravity, and then make a second level of the frame on top where the mechanism is added.

for ease of use 80/20 and Bosch extrusion are tops. All you have to do is cut it to length, get the fittings, slide a nut in the groove, put a fitting over it, and screw it all in. After cutting and finishing the pieces for our frame, we put it together in less than 3 hours, and could have done it even faster had we been more familiar with 80/20. The only problem is that the connectors and such for extrusion start to be VERY expensive when you buy a lot. You can make your own, but that requires machining abilities.

Stylin'... Cant help ya there, our team has never made anything that could remotely be called styling in recent years

Oh, and the whole rookies getting a premade chassis thing... they arent getting a premade chassis, they are getting two pieces that can be used to form a chassis... M is not trying to give all rookie teams a prebuilt frame. The point is to get some sort of guide that a rookie team, or any team for that matter, can refer to if they arent sure how to go about making a well built, reliable base for their robot. This guide is essentially the same as any white paper that has been written. How many people have been inspired by such white papers as the Technokat's series of papers on their successive transmissions, and go on to create a smaller, better, lighter version? Noone calls those papers a stem of creativity, so how is this any different? Some of the greatest ideas we ever get come from seeing something else that someone has done and improving on it.

Just because older teams didnt have the luxury of getting some of the "reduced assembly" stuff from FIRST doesnt mean that noone else should get it. What anyone who says this is saying is essentially "If I cant have xxxxxxx, then noone else can have it either", and is extremely unprofessional. Its not like teams are getting a crate with a prebuilt transmission and frame in it. They still have to figure out how to assemble all this stuff and make it work with their robot.

Is the creation of a guide to chassis building going to lessen creativity? No. Teams will do whatever they please with it, and I guarentee we will not see 900 cookie cutter robots out on the fields in March. How many teams did you all see last year that used he included frame members and had robots that looked the same? Few, if any. These things FIRST are providing are options to facilitate the building of a working robot, not required parts.

Sorry that was so long,

Cory