Proto Wall-E on Tri-Track

Let's Make Robots Projects Showcase
1

I’m in the planning phase of a new project, a Wall-E prototype based on the Tri-Track.
It looks very simple to get the broad outline right, pretty much just a square-ish box mounted on the chassis, then a pair of rudimentary arms, and a head/neck assembly. I figure 2DOF for each arm, plus a microservo for each ‘gripper’. The arms would be mostly for bling, not strong enough to do more than lift an empty paper cup. (Or garbage lid?..)

As for parts, here’s my starting point:

assembled Tri Track, the old 7v motor one, from an older project. (Low miles!)
shoulder-lift servos, either two quarter-scale ones (if I want to try for strength) or tw0 645 (or lower, down to 311)
shoulder-rotate servos, two 422 or 311 servos
gripper servo, two micro servos, provide no meaningful grip

(I think I just talked myself out of the larger servos!)

a ‘head’ from a recycled traxster, on a Base Rotate (w 422 servo) used as a neck
BotBoard II with Basic Atom
3 Sharp IR Rangers, 2 MaxSonar units, miscellaneous lasers and LEDs
digital compass and 2-axis accelerometer
expanded PVC panels (.25 in) for construction of body box
Sabretooth motor controller (2x5)

I have six of the super mini micro servos, I may try to fabricate a move-able brow of plastics or thin aluminum sheet. That may be too much work to start, so I’ll delay that decision.
The square body will provide plenty of room for batteries and other stuff. It most certainly will NOT be a functional compactor. In fact, I’ll be avoiding the industrial yellow look in favor of ‘prototype black’. I’ll need some special ideas for lights, it shouldn’t look too user-friendly.

I have the majority of the pieces on hand, so the cost of this project will be zero, or very close to it. Build time should be a week or two. Programming (adapting existing code) maybe another week. With luck, I will be partying with Will-E on New Years’ Eve.
Pictures will follow (mug shots, paparazzi, etc.)

2

Sounds good!

My youngest son gave me a Wall-E last year or so. No motion! Does make some noise…

Why not SRF08 ultrasonic rangefinders? or maybe the 04?

Compass and accelerometer could be useful, why not get a Razor 9DOF? What are your plans for these? I’d throw in a GPS, but mind you, compass and GPS may not work properly indoors, either you can’t see the sky, or there is too much metal (rebar) in the vicinity.

Alan KM6VV

3

Sounds like a whole lotta a fun! :smiley:

4

LOL
I’d love to have oodles of new sensors etc. but one of the main priorities for this project is to re-use components from prior builds. I even have the batteries from previous builds ready for recharging. Somehow, using ‘used’ parts to build a Wall-E has a certain justice to it, don’t you think?
The MaxSonar units are the E4, the most focused beam. The IR units are 60" and 30" range, so between sonar and IR, obstacles should be detected.
I’m not sure the compass will be useful, but the accelerometer will do duty as a 2 axis tilt meter.
The Rover program available here will be the starting point for modification. The arms will have short ‘expression’ routines.
This bot will have no real purpose other than to explore and be cute. Oh, and NOT cost any money!

5

OK, I get it. But remember what Johny (5) says:

“NO DISASSEMBLE”.

I see the justice!

Alan KM6VV

6

(sigh)
Ya HAD to do that, right?
In the interest of “No, not DISASSEMBLE!!!” I figure I have to get some new hardware.
A new Tri Track, ARC controller, Sabertooth motor controller seems to be in my future…
This gives me plenty of time to work on the boxy body, and I can use the existing chassis for MEASUREMENT PURPOSES ONLY!
I have a pile of sensors and such, so I won’t be cannibalizing for THAT. But this does up the ante, now I’ll have to do enough new stuff to justify the added expense.
So much for “not costing any money”. But he deserves the best, doesn’t he?
(Don’t we all?)

7

Yeah, you’ll thank me later!

It’s really nice to be able to compare versions of 'bots. I seem to make enough versions of brackets and other parts that I end up making a couple versions! Even 'tho I’ve designed the parts with CAD, and they usually come out as expected, there’s usually room for improvement, or another approach.

Alan KM6VV

8

Yeah, I often buy 2 of something, just to have a spare/duplicate. Hey, like the military says, why buy one when you can have two for twice the price? Hence the rather large pile of miscellaneous sensors and parts available for experimentation.
So, the purchase will wait until January, but it IS in the works. I have enough to keep me busy until then.
I’ve already made design changes to the box body - may not be as straightforward as it seems! And now is the best time to plan on including ‘bling’, like tons of LEDs, unnecessary lasers, multi-channel telemetry, etc. Trying to retrofit some of these things can be sheer hell, depending on the installation. It is best to design the stuff right into it from the beginning.
Another thing to consider: the new motors that drive the Tri-Track are 12v, while the older ones were 7.4v. That means batteries at 12v, 9v, and 7.4 (or 6) v. I could get that down to 2 voltages, I suppose.
And since I just happen to have several 434 wireless data links… and several gas sensors… we’ll see.

9

I try to design as much as I can beforehand, but that’s not always possible. To Wit: I’m switching to a 4 bar link jaw (gripper) for my Table Top 'bot, I originally had a simple pair of jaws actuated by a single servo horn and linkages. It worked as intended, but until I had tried out the jaws (in competition), I really wasn’t ready to attempt the 4 bar linkage and the pair of spur gears driving them. More parts, but it should be worth it for the improved action!

Alan KM6VV

10

I love four-bar links! With a little ingenuity you can do marvelous things with them. I am convinced the next ‘great’ hobbyist-level breakthru will be plastic multi-fingered grippers, made with several linkages chain-linked together to provide a compliant, but secure, grip. And only plastic will be light, strong, and cheap enough to be practical. Good luck with the gripper!
I found that I have eight of the super micro servos, so… perhaps eyelids (1), eyebrows (2), ears (2), and maybe another feature can be animated, at a low cost in weight or battery power. I’m hoping painted styrofoam will look good enough, so I won’t stress these el cheapo no-name servos. And I am envisaging lots of tiny hinges and stiff musicwire links crammed into a limited space, so this will be a challenge to assemble.
The movie Wall-E has arms that telescope to get longer. This I’ll have to pass on. A semi-functional gripper (open/close with 2 more micro servos) at the end, made from styrofoam, is all I’m going to do. Two servos (normal) at the shoulder do lift/twist, and that’s all for the arms.
That comes to 11 servos, 7 of them micro. Add 2 more for pan/tilt, totaling 13 servos. None of them move any real load.
I have about a dozen lasers to select from, in red and green. I have more LEDs than I care to think about, in plenty of sizes and colors. I have a 3.3v switching regulator, nice 'n small, with plenty of spare output pins (from Futurlec). I have an SD card reader (also Futurlec) for insane storage of data (up to 2G). Add in a pair of IR motion detectors (Sparkfun). Some 434 and 834 transceivers for taking the serial line wireless (comm to PC). One Sinewinder light. And enough NiMh batteries to keep myself happy.
I am a wealthy man!
So the head is going to require a lot of work if it is going to be in scale with the rest of the robot. I can start on the head right now. And I’m still thinking about possibilities for using that boxy body for … a houseplant? A shoe? A houseplant in a shoe? Nahhhh…

11

I don’t know about using Styrofoam, but there is some expanded ABS (?) stuff that is light weight, and would probably do the job for you.

Should be fun to see!

Alan KM6VV

12

Aaarrrrgh!
You ever try to cut something -perfectly- square, using less then perfect tools?
I was trying to cut a Sintrex 12x12 into 4 perfect squares, or at least 4 identical right rectangles. It ain’t as easy as it looks! My measurement marks are accurate, but the power tool vibration (skillsaw) means I’m creeping off-line after an inch or two. I didn’t WANT to do this with a coping saw, but it looks like the best way to prevent wastage. My “shop”, a table in the garage, is also less than ideal for precision work.
But the box body WILL be made, and possibly hinged. A great place to store batteries, and plants.
OK, so it is behind schedule, aren’t we all? I blame the holidays. Still, it leaves me with time to complicate my life with additions and improvements to the bot-to-be.

13

I like the bandsaw.

Cut your parts a little over, and use a mill file to finish (or a CNC mill…)

With a good scribed line (use a metal scriber), you can cut rough with whatever you have, and finish up with file. when it gets close, you can put the file flat on a workbench, and slide the part along it. Observe where you’re still high, and adjust pressure on the part accordingly.

Alan KM6VV

14

Gee, Santa, I’d LOVE a new bandsaw!
I’d settle for a used bandsaw. As it is, I’ve got either a jigsaw or a hand coping saw. The coping saw is certainly precise enough, but I was hoping to get a clean enough cut from the jigsaw to glue the edges together. No deal.
Labor-intensive is the way to go. Just takes longer. The plastic glues well with that 2 part stuff used for PVC piping. Once the pieces are square and plumb, bracing the pieces and gluing is easy.
While the box body cures (10 minutes) I can measure the Tri-Track chassis for where the cutouts for the motors will be. And figure out how to connect it with a quick-disconnect feature, so it can be removed for maintenance or upgrading.
Now I just have to go do it.

15

Yeah, sometime 'ya just got to work the problem!

Measure twice, cut once!

I managed to break three 1/16 endmills tonight, not sure why at least on the last, but now I’m out of endmills long enough to mill the final outline of a bracket I need for my new jaws.

Oh well!

Alan KM6VV

16

Milling!!!
I feel so lo-tech… might as well go bang a few rocks together LOL
I have to do mostly hand tools, nothing more complex than a power drill. OK, a Dremel, but the point is still valid. (Hidden pun, for extra credit!)
A great many of my ‘measurements’ are ‘cut-to-fit’ types, ie. place components, lay wire between them (and a loop for strain relief), cut and wire it in. For chassis pieces, once the base is set, I ‘mount, mark, and cut’. This way no ‘chain errors’ build up. Also, I remember that it is easier to remove material than it is to add it back on.
So, while my progress is agonizingly slow sometimes, I don’t make many fundamental errors.
Not many.

OK, but not THAT many!
Now I have to go knap a flint so I can hunt dinner mammoth…

17

Even if it’s a one-off, planning (and drawing!) as much as you can beforehand can be a useful exercise. Think it out as far as you can in your mind! Plan all your cuts and drills.

Lay it all out, machine the most critical aspects first, try a few fits, then machine some more…

This way you will develop skills fast. CAD is your friend! You can often “assemble” parts in CAD, even if you don’t have Solid works.

Even if I don’t require an accurately drilled hole or edge, I like to see how accurate I can be. Then when I HAVE to be very accurate, it happens!

[class dismissed/]

But I’ll bet you already know all that!

Alan KM6VV

18

Quick update:

“Life” has again intruded on my precious robotics time. I am behind in everything.
This has also allowed me to modify and re-modify my plans. My panels for the box body are OK, and I’ve made provisions for ‘bling’ that will enhance the look, but do nothing for functionality. I may even include an older OoPic board just to handle the LEDs and micro-servos. The ‘arms’ will look a lot better but will still have no real ability to do anything more than look good (I hope!) and wave about at random.

I have decided that the body will have a hinged front just like the real Wall-E, with a servo for operation. A real seedling in a tiny cup (shoe?) would be the icing on this cake. I figure on room for about a 2 inch seedling. Of course, once it gets bigger it would need to be replaced, but seeds are cheap.

Now if I can just get these pesky real-world issues out of the way… and if I get my camera back from the borrower…