Larger is easier
For building the mechanics and the frame and fitting it all in: bigger is easier. But building bigger also means bigger motors, bigger treads, bigger batteries and more expensive components.
Wow, definitely cute! I like
Wow, definitely cute! I like it.
Expense? Hah! This is
Expense? Hah! This is only a “problem” if you don’t have money coming out of your ears like me.
But seriously I am pretty broke right now so that does present a problem. Also, I’m 22 and just barely employed, and saving money is supposedly a good idea. Or so they tell me. Also I don’t have magic ears that spout money.
So yes, you have a good point. I think my justification comes from the fact that I’d like to have a project that I can work on for a long long time and continue to add on to. For example, I’d like to start basic with an ultrasonic rangefinder and a simple panning (not tilting) head. However, over the course of a few months I’d like to add IR edge detectors like yours, more degrees of freedom for the head, arms, more complex programming … perhaps even speech if it’s possible. My dream is to make a robot that impersonates emotions. Just like you made Edward seem “curious” by giving him the ability to look up, I’d like my robot to be able to do that as well as execute other emotive expressions.
Perhaps you had similar intentions with this project? I may be completely off base in my assumptions. If I start a robot with the intention of modifying its function and design down the road, will I encounter major problems? For example, if I make his head only pan to begin with, will it be unreasonable to assume that I can later add the ability to tilt?
Complexity
Well off course you can add the tilting later. Edwards neck is just two pieces off PVC directly screwed on the servo mount. I cut out a bit of the neck to mount the tilting servo.
There are a few downsides to add more degrees of freedom. The tilting servo in Edwards head cannot turn all the way down because the down movement is limited by the neck. Adding more servos means the movement limits of one servo will become dependent on the positions of the other servos. So apart from the mechanical complexity you have to program those limits to prevent overloading the servos…
A robot that can move its sensors in various directions also adds to the complexity of the obstacle detection. The program Edward runs in the video just check a threshhold on the sonic sensor and then jumps to a subroutine to determine whether to turn left or right. It doesn’t check whether the object is detected looking slightly left or slightly right or up or down, but it should. So more degrees of freedom and more sensors also makes the programming harder.
Anyway: I’m 37 with a son of 1,5 years and twins on the way. I have a reasonable budget, but very very little time and even less time in a couple of months. Like you I dream of building a bot with many functions and lots of cool movements and expressions, but if i ever want to finish something I have to keep it simple. So I spend a few weeks experimenting in the evenings with electronics on a breadboard: testing sensors, motors, speed and chips. Then I decide what ideas to steal for a bot and finally building it. My advice is to start simple and add complexity later; just like you said. If your budget is tight: start off the Frits! way with the paint sticks and doublesided tape, so you can easilly try things out and reuse the parts.
If you’re look for really long term projects: check this guy out! http://bakercraft.net/dan/r2d2/r2d2_index.htm
Fantastic casing, can you
Fantastic casing, can you say a bit more about the construction? Are the various panels of ex-PVC glued together, or bolted somehow? Is it easily cut/drilled?
construction
Most of the panels are screwed together. I found these tiny screws (2mm diameter, 10mm length). I drill a tiny hole in the PVC (1mm) and screw.
The base, the front and the back plates are glued. I posted some drawings of those somewhere in the replies in this topic.
You can cut the PVC with a sharp knife, but most of the time I cut the plates with a saw and finish off with a dremel.
Ah, I was actually going toAh, I was actually going to ask about this. Sawing and Dremeling was what I was going t do to cut the PVC, so I’m glad to hear it worked for you.
For my next robot I ordered some 3mm PVC, just to make a chassis. This will be a basic wall-avoider. The one after that, though, will be my Edward/Wall-E - like robot. Would you recommend getting 6mm PVC for that? I’m guessing 3mm wouldn’t cut it for that.
Any chance you could post some close-up pics of how you drilled the holes and screwed the panels together? Was it fairly easy to do? In other words … could I figure it out for myself, or did it take you some trial an error?
PVC
It was mostly trial and error. I chose the 5MM PVC because it was more than sturdy enough for edwards size and because the smallest screws i could find were 1cm long. 3mm will probably be enough for a small bot, but if you use thicker plates you’ be able to screw in the side of the board. My 2mm diameter screws are too wide to fit in the side of 3mm PVC; at least with my unsteady hands.
If you got your PVC at solarbotics (http://www.solarbotics.com/construction_materials/) I’d recommend getting some 6mm board as well. Just to make the baseplate.
I started out with the idea to make a frame of 5mm PVC and then make the covers out of 2mm board. I ended up using mostly 5mm plates because of the option to put screws in the sides.
Anyway: I bought a toy voice recorder that i’ll be trying to fit inside edward. I allready put a “wwwwall-eeeeee” sample on it and it runs on 5V so that shoudn’t be a problem. I’ll take some pictures when I take edward apart.
PVC
Thanks for your response, mint.
Yeah, I got the PVC from SolarBotics. I think I should have ordered 6mm, even for my smaller bot. I’ll still make it work for the smaller one since I’ve already purchased it, but yeah I think the 6mm would be much better for my Wall-E bot.
A voice recorder?! That’s awesome. I really want to do that as well. Voice-activated would be even cooler. 
Here’s a random idea I had for my bot’s code: make him able to recognize something that’s both moving (alive) and short. In other words, babies, kids, pets, etc. Then, have his “mood” change and use the cute sound effect that Wall-E makes in the movies when he’s interacting with the cockroach or whatever else. Think it’s possible? Could end up being more work than it’s worth, but my family would get a kick out of it if the bot made cute sounds and looked “entertained” by their babies. My cousins and extended family have about 5 babies right now. It’s crazy. Plenty of test subjects.
The voice recorder is pretty
The voice recorder is pretty funny. It can hold 1 sample of max 6 seconds and costs 3 euros. I took it apart immediately and found that it runs on 3 button-cells (5V) and the play button just pulls on of the chips pins low. Very easy to hook up to a picaxe board.
I think 3mm boards will do fine for a smaller bot.
I’m thinking about some kind of object recognision program, but with these sensors and the limited processing powers of the picaxe (positive integer math only and just 4KB program memory) I think it will be hard. moving “targets” like pets and babies will even be harder.
As for the babies. My son is 17 months old now and he allready messed up Edward once. I took out the batteries and he was so disappointed that Edward didn;t move anymore that he hit him on the head, breaking the gears of the top servo. If you don’t like to do repairs; keep the robots away from the destructive powers of babies!
Oh no! I guess I’ll either
Oh no! I guess I’ll either have to baby-proof him or just keep a really close eye on kids. I know I should keep them away entirely, but I just can’t resist seeing a kid’s face light up when she interacts with a little robot. 
Wow, 3 Euro? Not bad. Where did you pick that up? Is it essentially one of those things they put into talking birthday cards, or is it more sophisticated than that?
voice recorder
I found the voicerecorder in a tiny shop that sells housekeeping items and a few toys in my neighbourhood. It is a keychain thingy with a LED-light and two other buttons for record and play.
Sound quality is not very good, but OK. I haven’t checked if its a piezo or a regular speaker. I’ll post pictures of it when i get the chance
Pieces used in circuit board
What other componets did you use on the circuit board, besides the 28 picaxe. Were trying to build a similiar one and were not quite sure what componets to use on the circuit board. Could you also post the programming you used, please, were not very good programmers.
Thanks
Components
Well. The board is basically bits and pieces from the picaxe manuals. Check the examples, they are pretty clear. Besides the 28X it has a L293D motor driver IC and two 256kbit (32KB) eeprom ICs and a 5V regulator. I’m sorry I dont have any design to show you, because it was done sort of on the fly.
I’ll add the code to the page. It is the 1.1 code which is a bit old. The current code isn’t working well and I’m rewriting lots of things. It’ll at e least give you an idea of what I’m doing.
WOW
WOW!!! This is my favorite robot. Nice job! I love the complete design look.
Who said a robot looks like
Who said a robot looks like it’s creator?
Dimensions and Circuit Pictures
I was curious to what were the dimensions of the box of his body? It seems large but its hard to tell. Could you put another view of the circuit board? I want to see how you arranged some of the objects on the board, considering it being a custom board. This is a awesome robot! Nice work!
The box is 10.5cm wide, 9cm
The box is 10.5cm wide, 9cm deep and 7cm high (not counting the mounting stuff for the wheels) The circuit board is 8 x 5 cm which is 2cm longer than the picaxe 28X start board and just as wide.
I may post some more pictures of the board later. it’s a bit of a job to take it out of Edward with all the messy wiring. I can add the same picture that I posted earlier with some notes addded.
After 3 hours 
of sleep and a quick breakfast, I’m off to work.
Excellent basic, simple, sturdy design
I always respect home engineering. Custom making your own processor board was really impressive. Looks like it could handla indoor and outdoor situations. Do you have enough I/O for add ons? I am just learning parallax and have to get creative with external electronics to save I/O. The LCD in front looks very professional.