Let's Make Robots!

Jeffrey The Quadruped

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lumi's picture

Awesome....more, more, more please ;-)

Could you try to explain how the mapping is working? Does it require a EPROM to save data or do you just store it in te memory?

What servos are you using? With my Chopstick Junior I got some broken after a while...yeah, that cheap 9g servos...



Botdev's picture

You don't need the write it in the eprom, it keeps a very small amount of data in realtime (does not keep a log), so the memory is enough. Although, you can use the same concept in a way where you log the data for more complex calculations.
It has a very low resolution of 10x2. Basically what it does it to create an array of distance values (from the IR sensor) as the head moves.
If you watch it as it moves forward, you will see a circular-like movement of the head, it scans 2 lines (one 90 degrees to the ground and one 45 degrees to the ground). I keep 10x samples for each line and store them in an array. After that it depends on how you process that array, for example Jeffrey uses the first line to avoid obstacles and the second line to avoid falling down of a table. 
For the first line I find the lowest value to locate the location of the "obstacle" and the highest value to find the correct place to move in order to avoid it. (the position of these values on the array corresponds to real physical positions since the scanning process is linear). I do the exact opposite for table edge avoidance. Of course, there are exceptions with extra actions, but this is basically how it works.
With the same method you can create a larger resolution array for more calculations, but of course the time lapse between the samples would increase.

Those servos do break. Jeffrey broke 2 servos till now. I plan to redesign its legs with a more solid structure. The correct way to avoid breaking servos is to build mechanical legs and control them via wires connected to the servo. That way you can take some of the tension off the servos.

Just seen your chopstick junior, its awesome :D 

lumi's picture

Wow, thanks for explaing that in such a detailed novel ;-) Now I can make myself an image about how it works.

Yep, Chopstick Junior was a lot of fun to build to show off and even doing a workshop in out hackerspace and let 50 insurance sellers build two of Chopstick Junior clones ;-) 

legwinskij's picture

Awesome ! I am currently working on quadruped but this one is great !

ChuckCrunch's picture

so can't wate for the rest  so hurry hurry hurry now now now  :P LOL  in the top video there is a sound like a piezo buzzer freaking out, live it sounds like some kind of bug

 groove job all round


Botdev's picture

Yeah, I purposely used a piezo buzzer to create a bug like sound. Love that sound. Also, adding sound to your robot makes it psychologically more comfortable to interact for humans. :)
I guess I will add a new project every day, too busy these days.

JerZ's picture

That is what is really striking about this bot. It has so much personality. Seems to be pissed off when things get in his way and the twitchy head thing I mentioned before. Like a grumpy mad-man! Perfect. LOL

Botdev's picture

I didn't even mention the angry/fearing behavior we have intended to reach, it's great to see that you got the exact same feeling that was aimed for. :D

JerZ's picture

I love how his head spins in circles then all of a sudden he's staring right at you. AWESOME!! Great job.

Botdev's picture

Thanks a lot ^_^