Let's Make Robots!

Semi-loose thoughts from a total begginer

I'll be using this blog entry to kind of introduce myself, and gather/organize my thoughts and plan my way into making my first robot but also receive any advice that might be given to me.

(relevant) background:

informatics

path of interests (line of thinking) that led me here:

re-sparked interest in rc helicopters; cat manifested too much interest in the micro helicopter I bought; helicopter dangerous for cat; bought micro rc car for cat; cat still interested more in rc heli than rc car; fear of gravity plus (more importantly) the realization that some knowledge in electronics would be desirable to get into bigger (outdoors) rc helicopters  =implies=> I must learn electronics to advance in rc heli flying & must learn robotics to make a robot that "apeases"/entertains my cat.

current (ordered) stock:

- bunch of breadboards; connecting wires; set of resistors, capacitors, etc; (cheap :x) digital autoranging multimeter; 2 DC micro motors + wheels; 4 micro 9g servos; HC-SR04

I've ordered all of the above after perusing through several robot projects and over-the-knee-averaging what I might need and then searching ebay for the el cheapo parts. Most of those above come from China, so I expect I won't have some of those in less than 3 weeks from now.

As for the "brains" I'm planning to go the Arduino way (I'll buy it locally) since I've already have a few friends that delved into arduino before, and some that are planning to follow my footsets into robotics hobby now.

Robot planning:

Stage 1:

  Learn basic electronics;

  Learn basic arduino programming;

  Proper planning and building of basic 2-wheeled obstacle avoiding begginer's robot.

Stage 2:

  Assess the performance (according to own's expectations) and cat's interest in robot :p

  Try and model the the robot's behaviour according to cat's reactions (trying to guess beforehand, I'll have to to code something like: move robot semi-randomly -> stop it in lurking mode -> wait for cat to approach and investigate -> detect cat's proximity & activate some jiggling mechanism that will either startle the cat or entice it to paw the robot.

Stage 3:

  If by this stage I haven't burned out my components (and budget) and/or my neurons and patient and I feel I can progress in the hobby I would like to try a jab at making it (or a new robot) be controllable via home router. mount spy cam + wireless module and whatever necessary to check out what's happening at home while at work...

Stage 4:

  TBD... Time will tell...

 

LIMITATIONS:

- budget (student's budget :/ )

- space (small apartment), meaning I don't have a lot of space to work with large robots or more fancy materials that require big power tools and whatnot.

- time, alas I don't have all the time in the world and on top of that my time managing skills are sub-optimal; plus since I usually very skeptical-cautious I tend to do many things slowly.

ADVICE I ASK:

- any, which you might seem useful for a begginer like me.

- any major logic flaw/pit-I-might-be-stepping-into that you might notice on my plans (althought at the moment they are quite unspecific)

- CURRENTLY, what PLAGUES me more is "raw construction" materials, like for making the base for a 2-wheeled robot. I know there are several commercial available choices for that, but I would like to be able to make whatever I want according to my own specifications. So I want to know opinions on easy to find materials, easy to work (without need of fancy power tools) but still durable enough for robots that don't crumble apart at first run, and also non-toxic. (I thought about plywood, not sure about how durable it is)

- any tool, material or so that you might think I should have as a begginer.

 

Thanks for reading and I hope that in a few months (considering I might have to wait up to 3-weeks for the 1st batch of parts) I might be able to actually post a robot project of my own (for starters)!

 

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You got already some good advises but I still have one for you :-)

What's better for a cat than a mouse...no...not a living mouse...they tend to end up dead but a robot mouse like mine LMouseR.

Ok, maybe not the best choice to start with since it's very limited space available but if you scale it up a bit ;-) For the base/chassies you can use almost everything, just find the right and for you good looking part.

Looking forward to your creation...

Very nifty your mousebot :)

But yeah, it's a bit tiny for my begginers' blunder fingers, still I've saved it for future reference keeping in mind that I have a few pc mice shell just laying around :) I expect that my first project will look like a bundle of random stuff strapped together, I just hope that I can make it work at least :)

For basic chassis building materials, an old CD/DVD is pretty sturdy. You can just mount stuff to it with double-sided foam tape. Cheap, but it has worked for me before :D

I had actually considered using DVD/CD as support material (upon seeing a bot [perhaps yours] being built around a couple of disks). But was wondering and discussing with my friends on how easy it would be to drill the disks, and being told I wouldn't be able to do it at least not with some sort of manual drill. I do own a power drill, but I do think it's overkill since it's one of those models used mainly to drill holes into walls (and I actually never used it *cough* paranoia *cough*).

it would seem that drilling them is not much more than being safe (wear eye protection) and using a good bit. I have seen images of both 1mm and 3mm holes drilled through CDs. You should be fine, if you choose to use CDs for a base material.

Well I've been wanting to acquire some eye wear protection for a while now, now it seems I've gotten myself a valid reason :)

What type of motors? Are they small gear head motors out just small DC motors? If they are just motors, you may have to convert a pair of servos to continuous rotation, because, it is likely your motors are high rpm and low torque. All that means is that as they are they won't move your bout or your bout would be stupid fast. Re: building materials. Period, expanded pvc has been mentioned, foam board for a small two wheeler, you might be able to free form it, if it is light enough.

I went for a pair of these:

http://www.ebay.com/itm/2-pcs-Smart-Car-Robot-Plastic-Tire-Wheel-DC-Gear-Motor-For-Robot-/170821730348?pt=BI_Robotics&hash=item27c5c4c02c#ht_1958wt_1139

I went for them because I saw several at-least-looking-like-these being used on some projects over the web. I also read that some might be of dubious quality, but when I tried to go into torque vs. load vs. velocity to try and calculate the specs of the motor I would need.. well I got overwhelmed first because I went head on at too much physics at the same time, second my lack of hands-on to help me perceive what I would really need.

As for PVC foam seems like an option to try, if I can get my hands on some of it locally. I'll direct inquires to some artist friends and modelers as discover if there's a source nearby. thanks :)

looks fine. If it is too fast, you can always trade the wheels for smaller models. :)

Re: foam core. I believe it is indeed an art supply kind of item.

Chris the Carpenter ( CtC ) commented in another thread that expanded PVC has a brand name here in the states of Azek and it is found in hardware stores.

EDIT: finally had my hands in a couple of PVC exp. foam sheets and well 3mm is too bendy and the other option 5mm seems to be adequate, also it was only half a square meter so it's just as well so I bought that one.

After much discussion and local research I've found that there are actually a couple of shops within walking distance that sell acrylic and an assorment of different plastics.

Since I don't have quite a practical grasp on how flexible expanded PVC is... can you advise to which thickness should I aim for? They sell it from 1 mm up with 1mm increments, but each milimeter doubling also doubles the price of the square meter :s So I would want a board/sheet just thick enough to not bend with the weight of the stuff mounted atop the future robot... any ideas?