Hexapod - mach7ne

Lynxmotion Legged Robots
1

Hi, I would like to introduce my self. My name is Maciej, and I am writing to You from Poland. Anyway, I was born in 1981 :slight_smile: and I remember that shock, this “wow” feeling when I first watched Star Wars. I was like "this is the best story ever, R2D2, C3P0, this robots, this whole story… I remember at this time I had a friend that was lying to me that he had a robot in his basement, i was so curious to see it but he never showed it to me, I guess he had some sort of exuberant imagination. Anyways after all these years, this little spark lightened in my mind, make a robot.
I dont really remember how or why I found a video on YT demostrating this walking 6 legged robot.

So with some very little knowledge about electronics and some strong basic knowledge in programming I started my journey. As my body parts i chose a model designed by some guy from google i guess, here is the model if u like to check it:sketchup.google.com/3dwarehouse/details?mid=f415dda626738f4f58650ec7480a8da0&ct=mdrm
I dont know why i chose it, maybe because I like wood.

Another why I am posting this here is that I was reading through this forum a while, and I just feel that people here are extreamly nice and helpful its just amazing.

And another why, maybe someone will feel interested in some testing and developing the code from some guy from google, I have no interest in advertising google so…
the code is open, u can use android device, and use its features. Logic is ran by and Arduino Mega ADK board + an Android device. I will try to add a ssc-32 to this system.
At this time I have no idea how to mix it all together but…I like problem solving :slight_smile:

So greets to all of you robot junkies here, and thx for all that info and support.

I will post my progress on programming, electronincs and build parts, if You are interested stay tuned.

here is also my blog, i am posting my progress there, You can check some photos too:
makerobot.wordpress.com

2

I like wood parts… :wink:
I want to see more… and more… !!

3

thx for checking it out :slight_smile:

just realized I started 666 topic in this forum category, fear me :slight_smile:

4

Hi and welcome.

Nice looking parts and I too would like to see more.

Kurt

5

Welcome! Looking forward to seeing how your first project all comes together.

6

thx, its really nice to hear from U. I am printing out the source code to study how it works, I think I got obsessed :slight_smile:
The thing is really interesting with the arduino adk + smartphone for the logic.

7

Hello all, got a little update, I have gathered all servos(dont ask me how I did this…), and since my favourite colour is BLACK i added accents of it:
I have upgraded it with the braided cable 4mm diameter, and ended with heat shrink tubes 5mm diameter.
Here are some photos:

8

Got a little update. Of course I have painted servo horns in black, screwed everything together and here is a resault.

Hope U like it, next the electronics and code part.

9

Looks Great!
Kurt

10

Looks very good.

So how does it move with all that wood?

Alan KM6VV

11

Nah, it’s far away from walking, but everyday i’m making little steps to make this servos move. Since it is my first attempt on making robot, I still need to learn bunch of things,
and in case of hexapod and electronics its good to know what U are doing :slight_smile:. Since my budget is close to null, i cant’ buy ssc-32, so i chose to make a shield for arduino mega, and control all 18 servos from arduino.
Thanks to Kurte’s posts i know it can be done :slight_smile:. Now i need to figure out how to make connections from arduino mega to breadboard to control servos.

12

For a project with, as you indicate, “almost no budget” I’m sure I can speak for all here and say your approach is very professional - from the servo cable wrapping to the precision cut parts. Really hope to see it walking. Be careful about the weight.

13

It can be done. I have used my mega shield to control the servos for a hexapod. However I am not sure I could say that it was 100% jitter free. It was based on using a modified version of the Arduino Servo library, which I call ServoEx. It does the timed moves like the SSC-32.

The issue with Jitters, is that the Servo library relies on timer interrupts and having the interrupt handler setting the different IO lines high and low, for doing the pulses. The problem is that the timings will always be slightly variable as the interrupt latency will vary slightly just by which instructions are being executed. Then you add on top of this other interrupts, such as interrupts to handle the USARTS (putting something into a queue or pulling the next character out) and these interrupts will be more spewed. The worst is with things that disable interrupts, like SoftwareSerial disables interrupts for the entire time while a single character is being output… But again you can make it pretty good. Note: the Servo library (and as such ServoEx) can handle 18 (or more) servos on a Arduino Mega, but not on an Arduino that is based on an Atmega328 (like the Botboarduino, UNO, …), which can only handle 12…

I know your budget is almost 0, but you might try wiring up a board like the ServoShield (renbotics.com/servoshield.php)
Which you can get from(seeedstudio.com/depot/renbot … p-498.html). They are setup to do 16 servos, I hacked one up to do 18. I believe the underlying stuff is discussed up on their wiki page…

Kurt

14

At one time you could buy a PIC chip for the SSC-32, and wire your own servo board.

Alan KM6VV

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Still can, I think… jameco.com/1/1/2584-kae-t0v1 … -chip.html
But these are $29 each and handle 16 servos… Plus add a $16 mega prototype board, plus all IO pins plus Power buss, plus…
This would cost more than the SSC-32…

Maybe there are others.

Kurt

16

Earlier I believe you asked me what shield to try things out with first before starting making my own shields…

Servo-shields.jpg
Servo-shields.jpg800×428 35.6 KB

The bottom part of the picture show the shield on the Due, along with test equipment (my new 16 channel LA from Saleae )

Above in green is a prototype board, that I hand wired up for servos, which I originally used on my brat, before we had working prototypes of the Botboarduino.

The above in Red, is the earlier Renbotics servo shield, that I modified to handle 18 servos. I also had to update their library code to handle this, plus fix a few bugs along the way…

Kurt

17

Thx, as You can see i am not rushing with the project, so there is some time to play around with details.
Now it’s wight without electronics, batteries is around 1,7kg = 3,7lbs.

Thank You for the info. Since i want to learn more on microcontrollers and programming, i will try my luck with shield for the mega(first on breadboard) and implement the servo library to move servos, even with jitters. I like to know how things work, so its OK for me to see how the uC operates to control 18 servos.
And in three or four months time i will gather some cash for the SSC-32, no pressure with that.
I need to do some testing, so for now i’ll use a breadboard to send signals from arduino.
Thx again for info…

18

Hello again. Been a little busy lately, but i finally managed to wire electronics and started to test my robot.
Here is a little demo:

Now i have to learn more on IK and how to improve the code responsible for walking, so i may have a lot of questions :slight_smile:
The fun part has started :slight_smile:

19

It’s alive! Very nice to see it walking.

20

Got a quick question here.
I have a 6VDC NiMh pack to power servos ->hobbyking.com/hobbyking/store/__25030__Turnigy_LSD_6_0V_2300mAh_Ni_MH_Flat_Receiver_Pack.html
Today i fully charged them and they give like 7.25V, is it safe to power the HS-645mg servos with that voltage?
I am asking because i have seen a little smoke, but didnt check where it came from, in second i have disconnected them. :slight_smile: