Power Tool Cart

If necessity is the mother of invention, then laziness is it's dad. Take my latest project for example. At work, I have to push around an overloaded tool cart. It is the home to my main toolbox, hand and power tools, test equipment and the trusty vise. The thing is incredibly handy, I can load it up with tools, parts, etc, and go anywhere in the plant - a true "one stop shop." However, the need for convince has taken a toll on my back. No, I really mean it; this thing is heavy.

http://imageshack.com/a/img903/5144/BB2Edk.jpg

There must be a better way.

Observe, the RoboCart:

http://imageshack.com/a/img540/1180/SJWGa9.jpg

Ok, it doesn't look that glorious right now, but it is getting pretty cool looking.

The thing is a power wheelchair chassis and drive setup, with a cart strapped to its back.
I will be able to walk behind or stand on this thing and pilot my way around at work, toolbox and all, with just the use of a joystick. But wait, it gets better! With safe operation being such a concern around heavy machinery and people, the thing will have automatic collision avoidance!
Six Sharp IR sensors will scan pretty close to 360 degrees, when analog signal crosses a threshold value, two digital pins will open two relays that in turn open the X and Y pot wipers in the wheelchair joystick. Emergency stop buttons will open a main power contact.

Look at what I have so far:

http://imageshack.com/a/img537/2887/sYOCTV.jpg

http://imageshack.com/a/img911/1425/8vOp0t.jpg

http://imageshack.com/a/img903/3996/YArqAS.jpg

http://imageshack.com/a/img673/1130/HYh9Yk.jpg.

http://imageshack.com/a/img661/5444/Gffi6B.jpg

http://imageshack.com/a/img661/4163/Rlg32o.jpg

As you see, It has mostly been mechanical engineering so far, but as with all good cradle to grave projects, sparks are yet to come and magic blue smoke is just about to be released. And I plan on updating you along the way. I have some klunky code to run it now, but plan on revising and sharing what I end up with if anybody is curious.

Here are some pics of the sensors. I am making housings, so they can be smashed, crashed and kicked in the line of duty. Each housing has an led, so i can identify what sensor is past threshold value, a faulty sensor, or pretend that I can observe the scan times.

http://imageshack.com/a/img661/5844/WbVELN.jpg

http://imageshack.com/a/img913/492/HKR1K4.jpg

http://imageshack.com/a/img673/7774/MuvwhJ.jpg

http://imageshack.com/a/img540/149/6KObTn.jpg

http://imageshack.com/a/img661/5614/51TIhL.jpg

And some obligatory messy wiring shots.

http://imageshack.com/a/img911/157/61vd7J.jpg

http://imageshack.com/a/img673/6408/DFpf4v.jpg

http://imageshack.com/a/img537/8739/9iJ39U.jpg

Keep in mind this is very much incomplete. Much more crafting, wiring, programming, testing and general mayhem to come!

Sounds like a fun project. What do the H & S people at the plant think about it?

Weedpharma

I will be able to walk behind or stand on this thing and pilot my way around at work, toolbox and all, with just the use of a joystick.

I know that something homemade like that would never be allowed where i work. Also the cart with the tool chest in the first photo looks like it maybe significantly top heavy. Better let plant management know about your project.

Best roll around toolbox I ever had was bought from a retiring old timer, it was a 6 wheeler with 2 larger fixed wheels in the center and 4 smaller casters at the corners. The wheels were spaced up so when it was balanced the end casters were about 1/2 " off the floor. It was very easy to move and maneuver.
Something like that would be fairly easy to automate. Using a separate motor for each center wheel, it could be differentially steered like a BobCat, even spun around in place.

I've been thinking about something like this, but to carry tools and parts while at a "pick-a-part" yard. Those yards are large, with dirt and gravel as a surface - and numerous bits of car part "junkage" strewn around. The last time I went, I took one of those collapsible wire "shopping carts" - it worked ok, but at times it was a pain - especially as more parts were added and it gained weight. At the end of the time I was there, it was a bear to move.

Instead, my plan is to use an electric mobility chair base with knobby tires as the main platform. I'm not sure what I am going to do for control - it would be nice if it could work in an autonomous "follow" mode (maybe following an ultrasonic signaler I could wear) - but this idea of a joystick with collision detection/avoidance might be the better ticket overall.

I look forward to seeing the completion of your project!

Hmm - I just noticed in your pics that you're using a mobility chair as part of your "base" as well - you'll have no problem moving stuff around with that! Just realize that interfacing to the proprietary and safety-minded controls is easier said than done. In many cases, it's easier just to use a different motor controller - like a Vantec or similar.

Heh - you should make the undercarriage "frame" out of steel (with the casters attached) - then load the 24v battery pack at the front - then you could stand on the platform in the back and drive it around with your tools!

Thank you for the advice CrOsh. I have been struggling a little interfacing the powerchair's controller. But I really want to try my hardest to use it, because it is free. I figure as long as opening up the speed pot doesn't fault out the drives, ( I have used this method with some cheap perm. magnet drives on machines) I should be OK.

I was thinking about drive wheels in the center, with casters on all four corners, but I wanted to keep the wheelchair frame together, because all it needed was stretched 9" to be a perfect fit as is.

And for counterbalancing when the driver stands on the platform, well when this thing has my tool box bolted to it's top it will be just fine.

Question: If I continue to struggle with interfacing this thing with the powerchair drive system, what manufacturer's products would you use. This system is rated (OL spec) 30A @ 24vdc. The two traction motors are regenerating (when braking). A similar system has got to cost a pretty penny, even without the braking regeneration.

Keep on rocking!
And thanks for your ideas! By the way, is there a better website or forum for this topic? Somewhere garage engineers go to talk about ideas like this??

Thanks!

If I continue to struggle with interfacing this thing with the powerchair drive system, what manufacturer's products would you use.

I'd make a clamp on drive wheel powered by a rechargeable drill.

Hi,
Great concept and execution, I'm going shopping this morning and I'd love to have one of those follow me around the supermarket.

Might come back a dollar down but a shopping trolley up. (Got to use coin to unlock trolleys where I live)

Use 4 motors, one on each swivelling wheel, to give maneuverability.
(Could use Spirit, Opportunity, Curiosity type wheel system.)
Make a clip on set of larger wheels and axle to put on it and hang of the tow bar on the car to get to super market and backhome
Hmm possibilities.
My workplace is not big enough for one like your idea, jobs come to my bench 99% of the time.

Hope you have a spot to put an Arduino emblem.

Tom........ :slight_smile: