Let's Make Robots!

Se.Gu.A.Ro. (Sensor Guided Autonomous Robot)

Walks around and turns when it finds an object too much close to it.
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Hexapod_Final.pde6.51 KB
Hexapod2_left_right.pde9.38 KB

Hi there!!

I am proud to show you my first creation!

This is a 2DOF hexapod entirely built by myself with a bit of external help for the pratical part.

It walks straight until an object get too close to it (perceived with the ping))) ultrasonic sensor).

The project started 7 months ago when I saw by chance a video on youtube about phoenix which captured me! I started getting informations from the internet about theory, pieces and prices of servos and other stuff, then I sketched some ideas I had to make it move.. The movement of the legs is semicircular when they have to go back to the front but the hardest part was the one where I had to put together all the 6 legs! I spent months (of non-continiuos work due to study) on this but finally I managed to write a piece of code that worked! Then the rotation gait has been the subject of study for my last 2 months but, even in this case I managed to make it working!

The pratical part, that is the building part had been hard too because of the precision required to make the holes for the servos perfectly.. But!.. As some of you had noticed reading the forum (thaks a lot), I had a "little" problem about the wheigh that I solved lightening the body (made of galvanized iron), changing 6 of the 12 servos and (this is the modify that allowed me to make it working continuosly for over 13 minutes without stumble) setting the leg's end more close to the body. Surely I explained this last part terribly but forgive me (I'm not english :D)! These images will explain better:

This is the leg before:

And this is the leg with the new setup that allowed it to stay alive for over 13 minutes:

now the force that the servo has to apply is less than before and so he get "power up"!! ^_^

 

 

Here there are the steps which led to the final result:

 

Body lightened:

Finished (for now). I want to keep adding features like optional remote control, other (maybe) degrees of freedom.. Added:

  • sensor
  • arduino and pad wit pins for servos
  • batteries
  • double switch to turn on arduino and servos concurrently

The double switch and the 9V battery:

The sensor and the mess of wires:

The homemade servo connections:

More pics with explanation :)

Top view (relative to the board oriented normally, with the board on the robot this is the bottom view):

Bottom view:

The final result:

[UPDATE]: 

  • reorganized code in functions to have a clearer and easier reading (code attached)
  • added sequence for left rotation (left or right rotation chosen randomly)

[UPDATE]:

  • added bakward walking. Waiting for ps2 controller connector to enter fun! Code will be available after controller implementation [Temporarily suspended]

[UPDATE]:

  • added a servo to pan the sensor in order to get rid of diffcult situations like corners or surfaces at first not detectable! (watch video to see it in action!!)

Side view:

Bottom view:

  • added a new optional walking gait which is less energy consuming because all the legs, apart one, are always flat on the floor.. So the weight  is distributed over five legs rather than three!

[UPDATE]:

  • Started coding to implement inverse kinematics!! Yeah you heard right! I'm on the way to implement IK expanding Seguaro's capabilities by adding the third DOF to each leg!!

Suggestions (specially about code) are welcome.

Thanks for watching =)

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@LordGG:

1) Thank you very much! :)

2) the metal used is galvanized iron painted with a silver high resistent spray paint (blak one used for servo brackets)

3) I bent it with a hand brake for 90° angles and with a bending machine the others

4) unfortunately I'm not french (I'm italian) so I can't tell you the name of the device used (even in italian I ignore the name! :D) but it can be described as a pneumatic pump that you use like a crick (in the way you use the lever). This device has on the top two circular cutters (like those ones): one is fixed to the body of the device, the other one is linked with an axle. the more you pump the more it get closer to the other with the effect of cutting a hole. (before you have to make a smaller hole in the metal sheet, in order to insert the axle) 

I hope you understand what I've written! Otherwise I'll try to explain better! ^_^

Well, it seems Italian and French people use the same figurative expression ;)

Anyway, that's crystal clear, thanks for your answer and the link ! Iron is a difficult material to work with but you manage to find the good tools :)

Thx again !

Oh! very good! You're welcome! Yes, without the right tools, iron  is not easy to handle! But the essentials, in my opinion, are a drill press (or simply a drill) , a hand brake (or similar), and an angle grinder (useful to model the shape)..

I'm pleased to have been useful! If you have other questions, feel free to ask! :)

... if you insist, here is one more question :) About the legs... so you used the angle grinder to cut from an "iron sheet" the shape you wanted, but then did you also used the hand brake to softly bend the legs ? Wasn't it too diffult to be precise enough with a tool such as an angle grinder ?

.. I designed the shape on the sheet, I cut it in an L shape without touching the lines, then I bent it (the angles are around 45°, I don't remember :D) and finally I drilled some hole to lighten it.. I had to be very precise (in fact the legs are not perfectly equals) but I managed to do, imho, a good job :) (a cnc would be the top...)

Thank you very much for this detailed answer :) And yes, you definitley did a great job !

.. thank you again! :)

all these information are aimed to build an hexapod or what else..?

... I will soon work on an hexapod. Actually, I'm new in building robots. I've already built two basic robots, without using microcontrollers, analogic only. It was a bit frustrating, but I wanted to start with the basics, print the pcb myself etc. I'm done with that (for the moment), it was not fun enough for the very beginner that I am, so I'm currently following the LMR Start Here tutorial !

Untill now, I've always used plexiglass because it's an easy material to work with. I thought metals and especially iron were unaccessible for non-professionnals but you show me I was wrong. That's why I was so curious about the way you worked ;)

And yes, after a few more tests and work, I really want to build an hexapod (probably using 3 servos for a first try), I love the way it moves !

Thx for inspiration and advices :)

and I hope you succeed in making your hexapod! :)))

do you have experience in programming? what programming language are you learning/have you learnt?

I'm a .NET (C#) developper, but I also worked a lot with Java, Php, Perl, C/C++, basic, ASM... (for the last one, it was a looong time ago, and I don't miss it ;)

I followed the Start Here Tutorial this w/e, and I had a lot of fun ! I'll spend the next weeks improving the robot (addings sensors, leds, writing my own algorithm from scratch), and then I should me able to go further with an Hexapod :)

Are you planning on making an other robot ?

Thx !