2/3 Our Robot is Rolling!

I’m super excited about the progress we made today!

Those of you who were at scrum know that the frame was re-welded to correct a measurement error (my bad!)

After dinner, Jane and Harry pounded through and finished the work they had started with Mr Battis and others: putting the drivetrain into the frame. Yay!

Now our robot is wearing its “wicked knobby” tires, has all four gearboxes and CIMs bolted on. It has the tie rods that June, Donald and others have been working on, and they work great, first time.
! It still needs steering motors and electronics to become a drivable robot, but Harry and I couldn’t wait to see how much clearance it has on the low obstacles. We pushed it by hand under the Low Bar – piece o’ cake, half inch to spare. We rolled it through the Moat – no problemo! We tried it on the Rock Wall and found the steering knuckles hit just before the rear tires bite in, so we marked the spot that needs trimming. (Somebody get that tomorrow? One kingpin needs moving forward 1/2″ so the tire does’t touch the front bumper – we also marked in blue.) The Rampart will be a laffer; our robot is so skinny it can drive right up the left side and jump off like the Dukes of Hazard!

But will it be too tippy? We wanted to find out, so we put it on its side. Good news: It rolls back onto its wheels emphatically because its current center of gravity is an inch below the lower frame rail, about even with where the lower edge of the bumpers will be. Even after the battery, ball-launcher and winch are installed on the upper deck, the dozer blade should be able to “self rescue” the robot if it gets tipped onto its side. (Getting turned all the way onto its roof will probably result in a “stuck real bad”, but that would be quite hard to do and might be fixable with a nudge from another robot if we arch up with the dozer blade.)

We threw it on the scale…it’s just under 45 lbs. Awesome! We want to keep the weight down for climbing.

In the next couple days, let’s weld up a second complete robot frame, build gearboxes, steering knuckles, etc. (Harry and Jane measured and cut a pile of identical frame parts, so a twin “R2” can be built soon – it might even turn out prettier!)

Freddy, Thayer and I contemplated motor selection for the climbing winch – one Mini CIM seems the only logical choice based on the rquirement for both speed and power. With the 4-motor drivetrain that takes our CIM count up to 5, out of the 6 total we are permitted to use. The various sub-assembly design teams (dozer, flywheel, climbing winch, catapult winch) need to have a planning session ASAP to figure out which application must have the last CIM, and which could also work with gearmotors or snowblower motors. To help that discussion, examine the “Gear-Motor” spreadsheet I put up in my shared Google folder “Wells 3566 2016 season ƒ”. [Consider that real engineers will approach this, not as a competitive argument over limited resources, but as a team weighing options together and deciding which compromise or innovations will generate the greatest good for the team’s goals.]

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