27 Nov 2013 shimniok   » (Journeyer)

Robot, take out the trash!

Requirements | Design 1 | Design 2 | Chassis ]

I hate wheeling the trash to the curb on trash day and sometimes I forget. Screw that noise, man. A robot wouldn't mind, wouldn't forget and wouldn't care if it's freezing outside. I'm building Take Out The Trash Robot. TOTT Bot, for short. So there.

A few of the many Actobotics parts I'm evaluating
ServoCity was kind enough to send me a giant box of cool Actobotics parts to evaluate. Seriously. I'm like a kid on Christmas opening the coolest new lego-lincoln-erector-tinker-riviton-toy ever designed!

What the Isaac Asimov is Actobotics, you ask? Lots of cool parts. Precise parts. With drill holes in compatible locations. So, it's easier to prototype. Between the ball bearings, precision shafts and tubing, lightweight aluminum channel, gears, sprockets, chains, belts, and pulleys, not to mention ServoCity motors and giant servos I'm seriously giggling with glee here.

As it turns turns out, I've been wanting to build a trash robot for a few years now. After wondering "what am I going to do with all these parts?" for awhile, I decided the trash robot is the perfect project to see what the Actobotics platform can do for us robot-builders. It's going to take several weeks to build and I'm capturing it all here. Hope you'll tune in while I prototype, build, figure, calculate, screw up, fix, and all that joy. On to the problem statement...

The Problem

When you start any engineering project the goal is solving a problem. So sometimes it helps to actually know what the problem is. Oh, sure, you can run off half-cocked and build something really cool that has nothing to do with your problem. Have fun with that. You'll probably get on Hack-a-Day or something. Me, I like to get a good detailed picture of what, exactly, I'm facing. Crazy, right?

Problem: This. To curb.
I have rolling trash cans (pictured above) that need to get down the inclined driveway to the curb every Tuesday before 7:00AM, or by the same time on Wednesday if Monday was a national holiday. Getting up's easy. Figuring how how to grab this thing with a robot claw ...? Wait, how heavy is it?

Almost 50 lbs. Pretty typical.
When full the cans typically weigh around to 20-25kg (45-55lbs). That's a lot for a robot. No wimpy little robot is going to lift or pull these things around. And sometimes the cans are even heavier.

Size? About 0.41m wide by 0.93m tall (look at me, ma, I'm using SI units). The handle is floppy and is hinged at a height of 0.84m. The cans have 0.15m diameter wheels with a track width of only 0.36m.

Tippy much? Uh yeah. Their center of gravity is always high but varies. If I had a nickle for every time these stupid things fell over, spewing trash all over, while I'm dragging them to the curb in my jammies...  Well, that's some fun stuff right there.

Floppy handle hinges at a height of 33"

Angle finder shows about 6 degrees, steeper elsewhere
The driveway is inclined 6-8 degrees and the shortest distance from garage to curb is approximately 9m but the path isn't a straight shot. That's because normally my lifted, rusty, trail-prepped, rock-battered 1986 Jeep Grand Wagoneer is prettying up the driveway on the left. I don't know where I was when Google took this StreetView picture, odd... The robot will have to go around the big ugly truck. Without showing fear. The truck can smell fear.

My humble abode. Note trash cans and missing Jeep.
My wife's car is in the garage on the right when the trash needs to be taken out. To the left of the driveway are rocks. The trash cans are typically located where you see them in the picture. Eventually I'll relocate them inside the garage.

When the trash is picked up the trash collector lifts up the can and dumps it into the truck, then runs the cans back up to the garage where you see the cans pictured above. (It's a neat little value-add)

I should mention, too, that I only want to build one robot to carry cans one at a time, not some trash carrying swarm.

Alright, so that's the problem in a nutshell. Ok, sure, there's more details to gather, but good enough for now until I consider some possible designs for this trash robot.

Oh man, this is going to be great! No more trash carrying! Yes! I invite you to join in, follow along, subscribe, share, all that stuff.

Next Time: Evaluating Candidate Designs

Syndicated 2013-11-27 17:00:00 (Updated 2014-02-19 01:00:29) from Michael Shimniok

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