Let's Make Robots!

Beer Fetching robot, current state

This is the third or so generation of this robot.

The previous versions were all tracked, and the first few used a balsa wood frame. Many reasons for failure, mainly related to the two large 6v 12AH SLA batteries mounted in it (duh!).

Now i am using an old Asus wireless router with a USB port that runs linux as the main stressed component, and will be using it to its full capacity for wireless control and to interface with whatever USB dongles i can cram in once i get a 5v regulator so i ran run it from the 6v sla's

Current version has problems on carpet due to wheel size/lack of torque and the front+rear skids needed for stability.

The drive is via surplus Hitec servos (HS5475HB, come without PCB or pot) from Pololu which i then  fitted with HS311PCB's+pots - No axles, the wheels are mounted directly to the servo horns. Not the best solution (Lots of flex in there!) , so i will be looking into using a pololu motor controller and some cheap cordless drill motors for propulsion. Easier than adding axles and drive systems for both wheels, although that would let me do some reduction gearing.

 The arm was originally made from balsa wood as well, i have since changed to polymorph/shapelock plastic, using the axles from the tamiya track set as rigid struts for each lenth of arm.

 Current servo's in use are -

HS311 for wrist rotation and claw movement

Hs5475HB servos, modified with HS311 pot and PCB, two mentioned before modified for full rotation to drive wheels, one left standard for the closest joint to the wrist.

Next joint down from that is Hobbytech YM2763, which i beleive is rated at ~13kg/cm

The base is made up of a bair of GWS S04BBM servos, mounted together. One pans, while the other tilts.

 Too much typing, time for pictures:

Current state of things - First 8 pictures were taken with a phone, last 5 were taken with a camera at high res.


 Pictures of the post balsa-wood tracked state - Aligning tracks is much easier with drillable wood than the plastic.


 Until something breaks (most likely the servos powering the wheels) i will be concentrating on software, most likely python to control the servos, allowing playback and position capturing rather than manual positioning.

Yes i know the batteries are overkill. But you know what? The thing MOVES, and the battery charger i bought with them is still in its box, after over 6 months!



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I think on monster house some show that was on discovery or tlc they added a vacuum tube like you se eat the bank to bring someone at their chair watching TV a beer which was pretty cool but sucked since you'd have to wait to drink it. Talk about someone who needs drug treatment when they can't get off their butts to get their own beer.

It's not about getting off your arse to get a beer, it's about the challenge involved in programming the robot to even find the fridge, let alone open the door and find a beer amonst all the other stuff, pick it up without dropping it, close the fridge door again (without dropping the beer) then find you and hand you the beer (without dropping the beer :-)

Apparently training dogs is easier until they puncture the can and discover they like beer. After that you need to lock your fridge because your dog is an alcholic. 

For all the hassel involved, at least the robot won't drink your beer on you.

vinegar in beer cans
Can you get a relative picture, so we can compare the size to something? Like have a bottle next to it or something

Polymorph is great stuff.

There is one drawback -- it ages very poorly and gets very fragile over time.  I had a claw built from polymorph, that weakened so much it just crumbled and snapped.

I'm sure it was the effects of light and oxidation, a coating of paint would help a lot. 


I've never heard of this problem before. How long did it take to happen? Was it in sunlight a lot?