Let's Make Robots!

MR Get-a-beer

Gets me beer from the fridge, and delivers it to my location, will also take empty cans to the bin.


- First of all, Appolgies for the crappy pictures, I will be updating them with better ones, more info, and maybe some video.



I decided to build a robot that could navigate around the house, know it's location, pickup items, (bottles, cans ect) and move them to another location. Although I still have some bugs to fix, it mostly works.


The chassis is and RC tank made by Heng-Long, about $75. A good platform to start with, and lots motors and gearboxes for future projects, (and an airsoft pellet gun, woohoo).

Many thanks go to the inventor of HOT GLUE !!



JUST ADDED - VIDEO, Sorry the start is so dark, dark hardwood floors make for crappy video.

Here's what Mr Get-a-beer does in the video.

1. Uses ping to get the distance from two perpendicular walls, and sets it X,Y cordinates for navigation purposes. (not in video)

2. Goes to a preset location, uses ping to search for the closest object, and moves close to that object.

3. Scans with ping again to find the center of that object, opens the claw, moves in and grabs it.

4. Rotate the object (can) out of view of the ping sensor.

5. Navigate to the trash can in the kitchen, stopping at preset waypoints, correcting the coordinates using distances from walls measured by the ping sensor. The compass is used to maintain the heading, and wheel encoders measure distance travelled. Once at a waypoint, it updates the X,Y coordinates using trig functions. These waypoints are all entered into the program code.

6. Drop the object (can) at the trash bin, and return to my office for further instructions.


The foam attached to the claw is to stop the ping from "seeing" the claw and giving useless distance information. 




Wheel encoders are home-built using QRD1114 emitter / detector pairs, and a few resitors and caps. They are mounted inside the gearbox and give very good accuracy down to 1mm of robot travel.


View of the gripper, uses twine and a pully type system to get a firm grip on things.




 Future Plans for the bot :

1.Speed it up a bit (easy done)

2. Add voice control. I already have the say-it module from Parallax, I just need to tweak it to work with the propellor, since it is designed mostly for the basic stamp2.

3. Add another microcontroller and motors to my beer fridge, so MR Get-a-beer can instruct the fridge to open using IR commands. (it's only  a mini fridge, sitting on the floor). Grab a beer from the fridge, and bring to wherever is needed.

4. A possible upgrade to a 5 DOF arm to replace the crude gripper. This might require moving everything to a bigger platform.



UPDATE - Added video.  Mr Get-a-beer  cannow actually get a beer out of my mini-fridge. Finally it does something usefull. I had to split the video into two parts to get it off my phone.


UPDATE 8/11/2012 - just added a video if Mr get-a-beer going to the docking station for a recharge. I also added a pic of the html page that I now use to give commands to the bot.  I can now dial-a-beer from my couch using my iphone or any web enabled device.

Used used gadget gangsters E- net module and a netgear wireless adapter, there is no pc invovolved, the webpages are served directly off the robot, and connections are made through my home wireless network, i'm now using a second propeller chip which shares infomation with the primary motion control propeller. 


html gui interface


Also added pics showing recharging dock, with coax cable, and simple tin foil used as the connection.

Pics of the e-net module,  netgeat wireless adapter and second propeller chip onthe beadboard all crammed on the back of the bot. ( Time for a bigger robot I think)


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Is there anyway I can post a video on LMR without putting it on You Tube or one of the other video hosts ?

On the video, I don't think so. As far as I know you have to post it on a video host.


I like this robot.

nice work

Very nice robot! It seems perfect for my challenge: http://letsmakerobots.com/node/27789, what do you think?

Thanks King Kong,  The encoders are extemely accurate, since they are mounted inside the gearbox, one click (ie black to white transition) is less than 0.2mm of forward travel.  The compass is pretty good too, about 1 deg accuracy.  It's not tilt compensated, so it won't work on un-even surfaces, like outdoors. You would be best to use a GPS for outdoors.  The trig function uses floating point math, so it is more than accurate. 


The beauty of using the propeller is that you can use objects written by someone else, (like trig functions), even if you don't fully understand how it works. - no need to re-invent the wheel !!. Having 8 processors is good too, one can be dedicated to watching the encoders while moving, I have one dedicated to updating headings from the compass, you can be a bit lazy on the programming too if you have plenty of processing power.   

I Like It ;-)  And A Plus For The Coors Light Can, I'm Drinking One Now!

I just added video of MR Get-a-beer,  grabbing a coldie from the fridge.  The fridge has a second processor (propeller), mounted at the back to control the door opening actuators, the robot controls the fridge using IR signals.  I'll add more pics and details of this if anybody is interested.


Now to complete my navigation program so it will take the beer to the couch !!

I'll also be modifying the beer-dispenser in the fridge to hold 10-12 cans.

that can place an online order for you meh. groove awesome stuff 

This is great! I am learning deep in the robotics and my idea for first useful robot was also one that gets beer cans from the fridge!

And I wanted it to learn how my house is by itself creating a map in its memory.

I thought about mapping the house, and letting the bot choose it's own path, but my head just starts spinning thinking about it !  It would take a lot of memory to store the info.

This bot simplty travels via preset waypoints, using trig functions, the compass and wheel encoders to update it;s X and Y cordicates in the house, the ping sensor corrects errors at certains waypoints, to eliminate the cumulative error encounted by dead reconing. This method works quite well, provided nothing is blocking its path. It can move from one end of the house, to the other, and stop within 5mm of the intended spot.