Alright. I’ve seen some people ask how to make drivetrains, how to organize electronics, etc, so I think the CD community as a whole should help them out.
First off:
Building a Non-Kitbot chassis:
To build a very robust, non-kitbot chassis, you want the outside of the frame to be the largest part of your robot, then you want to make sure that there are plenty of supports and good fasteners. 675 uses 3/8ths inch Grade 8 bolts with a shoulder on them, and a washer on each side of the bolt. Gloria Machina, 675’s bot, is layed out like this.
http://www.lotechdesigns.com/host/images/8628GloriaChassis.jpg
The thin black lines are vertically-mounted peices of quarter-inch thick, 3 inch tall aluminium.
The maroon rectangles are the wheels.
The dark blue strips are the same type of aluminium, but bolted on top of our gearboxes to support the chassis and gearboxes.
The thick black strips are some other sort of material, and hold the stump of our arm, along with our ramp bracket and battery.
Not to scale.
Building a good Drivetrain:
First off, unless you want insane traction and a hard time turning with tank drive, steer clear of the KOP wheels. They’re very grippy and to lose traction, teams have had to cover them in plastic or zipties.
There are several different kinds of drivetrains you can do. You can do a direct-drive system with all wheels powered by their own motor (4 or 6 wheels works best for this), a chain-drive system with all wheels powered with their own motor/gearbox (again, 4-6 wheels), chain-drive for each side (2 motors generally, 4/6 wheels total), or some other interesting systems (like a 6-CIM drive system, or a 12-wheel system, not recommended for rookie or less experienced teams).
There are also several different types of wheels. Traction, Omniwheel, and Mecanum are the three most well known. Traction wheels have a grippy tread that gives, as the name implies, traction. The design on the tread can be all sorts of things, from a crisscross pattern, to a pseudo-car-tire design, to the kind of stuff that comes on IFI Traction wheels.
IFI Traction V2 wheels:
Not the two different types of tread. The kind on the left is called “Roughtop”, and the type on the right is called “wedge”.
Omnidrive wheels are cool. They are normal wheels in the sense that they are round and give you traction, but only forward and backwards. A common design for omniwheel useage is traction wheels in the center of a 6-wheel chassis, and omniwheels at the corners. This improves turning speed greatly over an all-traction wheel chassis.
AndyMark Omnidrive Wheels, 6in Diameter:
http://www.lotechdesigns.com/host/images/2026yhst-33833170891817_1942_2834515.jpg
Mecanum wheels are probably the coolest, however. The wheel design is similar to Omnidrive, however different in such a manner that the robot using them can move in any direction and rotate easily, allowing it to slide around much like a hockey puck. There is a special way of mounting them, however, and that is so that the 4 wheels form an X when looked at from the top down.
Mecanum Wheel, 8in diameter:
http://www.lotechdesigns.com/host/images/8556yhst-33833170891817_1937_1422730.jpg
Notice the staggered rollers.
Alright, well, that’s about all I can post about, as that’s about all I know how to do. If anybody who has experience with Pneumatics or Electronics would like to speak up, please do.
Thanks to AndyMark.biz and InnovationFIRST.com for the pictures, and making good prodoucts.
EDIT:
And to anybody who’s interested, I hope to find pictures or acquire pictures of our robot’s chassis and drivetrain. I know that a simple MSPaint diagram of a bot isn’t as helpful as one might make it out to be, but hey, it’s a start.
I also might make more diagrams later.
