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View Full Version : Solar Powered Coke Fetching Robot - Advice Please



phear_me
12-27-2011, 10:55 AM
Hey guys,

I am considering a (rather ambitious for me) project that, as you might have guessed from the title, will ultimately produce a robot that can, from the same starting point, fetch a coke from the fridge and bring it back to said starting point at the push of a button. I think I've got a good basic sense of what needs to be done and the tools available to get it to the fridge and open the door and I think I can even work out how to program it to go to autonomously go to the same sunny spot and recharge (though I know nothing about solar panels). How on earth I'm going to get it to recognize and grab a coke is beyond me. The easy thing is to always have the coke in the same place so it's an automated program with no variables - but I'd like to see if there's a way to get it to recognize and grab a coke from, say, anywhere on the bottom shelf. Let me be clear: All of this is way beyond my current skill level (hence the challenge of producing a robot that can get it done) and so I really need to get some community input on the matter. This is going to, for me, represent a dramatic uphill climb on the learning curve so I could really use some help planning the parts and materials for the project. I don't "know" how to do any of this off the top of my head, but I figure we'll take it one mini-project at a time.

I'm giving myself 2 years to get this done and I don't think cost will be prohibitive.

Anyone willing to help me avoid early mistakes via their experience is more than welcome to chime in.

Thanks.

Jorge P
12-27-2011, 01:34 PM
I'm no pro or advanced propeller user, But I think if you make a line on the floor from your start point to the fridge and have the drink in the exact same spot each time, a line follower might work. It would need to be strong enough to open the fridge and have a far enough reach to grab the can. Maybe one of those grippers us short people use to grab items higher than our reach, I don't recall exactly what they are actually called. I just know of them as grippers.

If you get this done you will have several football enthusiasts using one to grab some cold beer while theyre glued to the super bowl on TV.

Mike G
12-27-2011, 05:03 PM
How about putting wheels on a refrigerator and have the refrigerator come to you. I guess the refrigerator is outside - solar?

Publison
12-27-2011, 05:11 PM
Here's one our buddy Steve made:

http://forums.parallax.com/showthread.php?122809-Beverage-Delivery-System&highlight=Butlerbot

http://www.norrislabs.com/Projects/ButlerBot/index.html


(http://forums.parallax.com/showthread.php?122809-Beverage-Delivery-System&highlight=Butlerbot)

phear_me
12-27-2011, 08:50 PM
I'm no pro or advanced propeller user, But I think if you make a line on the floor from your start point to the fridge and have the drink in the exact same spot each time, a line follower might work. It would need to be strong enough to open the fridge and have a far enough reach to grab the can. Maybe one of those grippers us short people use to grab items higher than our reach, I don't recall exactly what they are actually called. I just know of them as grippers.

If you get this done you will have several football enthusiasts using one to grab some cold beer while theyre glued to the super bowl on TV.

Yeah, the line following approach is one that I thought of. Or, since it will always go from point A to point B I might be able to just write the code based on timing with enough flexibility to get out of the way of small objects that are in its way. Perhaps something with a GPS? Still, the line following robot is probably the easiest - especially given how much code is out there.

The arm gripper is definitely the approach I'm thinking - but I'm not sure how much torque it will need and so it's making me hesitate on choosing a board, engines, power supply etc because I'm not sure if my ambitions go beyond the microcontroller realm. The real pain is going to be some sort of visual recognition software to get it to recognize, locate, and properly grip a can of soda (and, perhaps, distinguish a diet coke from a 7up, but that might be asking a bit much).

phear_me
12-27-2011, 08:50 PM
How about putting wheels on a refrigerator and have the refrigerator come to you. I guess the refrigerator is outside - solar?

Unhelpful FTW.

phear_me
12-27-2011, 08:58 PM
Here's one our buddy Steve made:

http://forums.parallax.com/showthread.php?122809-Beverage-Delivery-System&highlight=Butlerbot

http://www.norrislabs.com/Projects/ButlerBot/index.html


(http://forums.parallax.com/showthread.php?122809-Beverage-Delivery-System&highlight=Butlerbot)

Very Cool. I think, from a programming perspective, my project is more ambitious because I'm going to attempt to get the robot to interface with a stnadard refrigerator. But from an engineering/polished perspective (using the trash can is genius) the Butler Bot is more difficult.

So my real issue comes down to - how do I get the thing to grab a coke from the fridge?

Spiral_72
12-28-2011, 03:43 AM
Just a couple thoughts, my opinion and is intended to help you with ideas:
The line follower would probably be the easiest to implement, maybe UV or IR or similar "Invisible" paint?

GPS may not be an option as a sole fridge finding sensor, resolutions is fairly poor, it'll probably put you in the kitchen, but not find the fridge, besides if this is inside a structure (your house) GPS reception would be hindered.

A prox sensor on the end of your gripper may find a can.... or any other metallic object so it may only be good for confirmation.

an RFID tag sticky tapped to the Coke carton might be a good idea..... either that or beside the loose row of cans on the fridge,

You'll either need a heavy base with powerful motors and wheels with a lot of traction OR some method of bracing the bot against the cabinet beside the fridge / bottom of the fridge and a powerful shoulder to open the door.

Maybe a 3" PVC or similar tube you load the cans into might simplify things, then an extended rod into the PVC with a suction cup?

Just having fun here. I suspect any micro could handle the task at hand.... Basic Stamp or Prop.

Mike G
12-28-2011, 04:03 AM
Unhelpful FTW.


I guess a mobile refrigerator is a dumb idea :(

Jorge P
12-28-2011, 05:43 AM
I guess a mobile refrigerator is a dumb idea :(

I don't think it's dumb, it would actually be doable since most home refrigerators already have wheels on the back of them to move in and out of place easier. Then you can market it to all the college students who want to have a keg-fridge with a tap. lol. Not only can they be couch potatoes, they can also have a beer and food an the push of a button. A new Fast Food! I suppose then you would want to program it to cook up some grub to.

I've had a similar Idea to create a cleaning robot that can cleanup my messes, vacuum, mop, and do some dusting, I've already chosen a name for it "H.A.I.R" ( Housekeeping Assistant Interactive Robot ).

phear_me
12-28-2011, 06:14 AM
I guess a mobile refrigerator is a dumb idea :(

My sincerest apologies if you were being serious. I thought you were trolling. Maybe I need to open my mind up a bit more to some of the creative possibilities that are out there.

doggiedoc
12-28-2011, 10:52 AM
My sincerest apologies if you were being serious. I thought you were trolling. Maybe I need to open my mind up a bit more to some of the creative possibilities that are out there.You'll find a lot of creative people here. Mobilizing the refrigerator itself is thinking outside of the box for sure!


Paul

Mike G
12-28-2011, 03:13 PM
Put aside the software and hardware challenges for a moment and think about the physics of your project. How much force does it take to open a refrigerator door? Will the fridge open the door for the robot or will the robot open the door? If the robot is to open the door, how long is the lever (arm)? How many joints? What are the forces involved on each joint? How large should the platform be to disperse the forces required to open the door?

A coke weighs about 14oz. If the coke is are one end of a 1ft lever that's 12in*14oz*sin(90) = 168 oz.in of torque felt at the other end of the lever. That is if the lever is perpendicular (90) to the force of gravity.

phear_me
12-30-2011, 01:22 AM
Put aside the software and hardware challenges for a moment and think about the physics of your project. How much force does it take to open a refrigerator door? Will the fridge open the door for the robot or will the robot open the door? If the robot is to open the door, how long is the lever (arm)? How many joints? What are the forces involved on each joint? How large should the platform be to disperse the forces required to open the door?

A coke weighs about 14oz. If the coke is are one end of a 1ft lever that's 12in*14oz*sin(90) = 168 oz.in of torque felt at the other end of the lever. That is if the lever is perpendicular (90) to the force of gravity.

Working on it.

kwinn
12-30-2011, 01:44 AM
Opening the fridge door does not require much force once the magnetic seal is broken. That can be accomplished by a small mechanical spreader (2 L shaped brackets that act like a vise in reverse) on one of the arms. For locating the fridge and the can inside it some form of visual recognition will probably be required, although locator beacons, bar codes, or other markings could be used.

Mike G
12-30-2011, 02:05 AM
Opening the fridge door does not require much force once the magnetic seal is broken. That can be accomplished by a small mechanical spreader (2 L shaped brackets that act like a vise in reverse) on one of the arms.


Very true but somewhat of a feat to position the reverse vise and swing open the door. What about an IR activated solenoid? The robot rolls up and asks the fringe to open the door.

Even better a sensor in the fridge that detects if a coke is present? The robot rolls up and asks the refrigerator, Hey man do you have a coke in there? A modulated IR response, "Yes, I have 3 cokes." The robot says, "Well open the door".

erco
12-30-2011, 02:19 AM
What's with the solar power?

kwinn
12-30-2011, 02:35 AM
......... What about an IR activated solenoid? The robot rolls up and asks the fringe to open the door.

Even better a sensor in the fridge that detects if a coke is present? The robot rolls up and asks the refrigerator, Hey man do you have a coke in there? A modulated IR response, "Yes, I have 3 cokes." The robot says, "Well open the door".

Both great ideas. Distributing the task to the fridge and robot simplifies it quite a bit. Fridge has a can waiting and holds it out to robot at a fixed location. Communication could be via IR although tones (as in R2D2) might be more impressive to the uninitiated. An IR led on the fridge could be used as a beacon for the robot to locate it.

If you want the robot to do it all take a look at these threads for image processing ideas.

http://forums.parallax.com/showthread.php?136496-Home-Brew-Camera-for-image-tracking.

http://forums.parallax.com/showthread.php?136086-What-s-the-best-way-to-do-this-interpolate&highlight=blackfin+camera

phear_me
12-30-2011, 08:12 AM
What's with the solar power?

Thought it would be neat if it automatically went to a pre-determined sunny spot to charge itself once it realized power was getting low and then returned when fully charged. Minimizes the work the end user has to do as the idea here is to create a project with an "ultimate man-bot" type theme as I think it makes it more fun, and gives me an excuse to learn more about solar power (diodes, etc).

phear_me
12-30-2011, 08:15 AM
Opening the fridge door does not require much force once the magnetic seal is broken. That can be accomplished by a small mechanical spreader (2 L shaped brackets that act like a vise in reverse) on one of the arms. For locating the fridge and the can inside it some form of visual recognition will probably be required, although locator beacons, bar codes, or other markings could be used.

The spreader could work - I hadn't thought of that - though it definitely changes the angle of approach.

I want to avoid having to tag or label the cokes. I want the robot to simple be able to go to the fridge, open the door, and grab a coke. I want it to "really" be able to do it without tape on the floor or labeling the coke etc. I wouldn't, however, be ooposed to the robot triggering a pre-installed servo to open the fridge. That doesn't feel like "cheating" to my (exceedingly arbitrary) view of the project. In fact, the idea about beeps and whistles could be an easy way to add a little flashiness to the project to spruce it up a bit.

Any clues on the hardware I might need for such a task?

= )

Mike G
12-30-2011, 02:24 PM
Any clues on the hardware I might need for such a task?


Parallax Eddie platform, MS Kinect, Laptop, Microsoft Robotic Studio (MSRS)

kwinn
12-31-2011, 07:37 AM
The spreader could work - I hadn't thought of that - though it definitely changes the angle of approach.

I want to avoid having to tag or label the cokes. I want the robot to simple be able to go to the fridge, open the door, and grab a coke. I want it to "really" be able to do it without tape on the floor or labeling the coke etc. I wouldn't, however, be ooposed to the robot triggering a pre-installed servo to open the fridge. That doesn't feel like "cheating" to my (exceedingly arbitrary) view of the project. In fact, the idea about beeps and whistles could be an easy way to add a little flashiness to the project to spruce it up a bit.

Any clues on the hardware I might need for such a task?

= )

You could have the robot command the fridge to open using telephone touch tones using either the tone encoder/decoder chips or micros although an IR solution is simpler (IR led and receiver). No reason you can't have sound as well though.

Locating untagged or unlabelled cans in the fridge would most likely require a vision system unless you stacked them on a rack that allowed the cans to roll forward to a specific location. The rack could also have a led for location sensing.

phear_me
01-01-2012, 01:39 AM
You could have the robot command the fridge to open using telephone touch tones using either the tone encoder/decoder chips or micros although an IR solution is simpler (IR led and receiver). No reason you can't have sound as well though.

Locating untagged or unlabelled cans in the fridge would most likely require a vision system unless you stacked them on a rack that allowed the cans to roll forward to a specific location. The rack could also have a led for location sensing.

Gonna go with the vision system.