Basic Quadruped Platform!

I wanted to make a simple barebones platform that could have something like a raspberry pi connect to it and control it. This way it would be easier to update and have more complex abilities. With the Arduino only concerned with moving the servos with commands from a Raspberry pi. The Raspberry pi could run more complex programs, multiple programs, and has  more communications ability (with wifi and Bluetooth) that would make the robot not only way cooler but allow for easier debugging. This also allows you to have a lot more sensors and servos, since you can control a couple of Arduinos with one Raspberry pi.

MATERIALS!

Structure material (wood, 3D print material, aluminum...from soda cans?)
Microcontroller (I am using an Arduino UNO)
Servos( I am using 12)
Battery 
Mounting hardware

Tools

Zip ties
You might want to use jumpers or wire extensions  for the servos.
Hot glue gun
screwdriver
Razor/Dremel/saw (depending on what you want to use for the structure)

First choose what shape and size you want your robot to be. You want to leave enough room for the Arduino, Battery, and always leave room for pi. You also need to mount the legs to the body. I mounted them on the bottom to save all the room on top for the electronics. before cutting out the body mark where you want to put everything. Drill the holes for the Arduino and battery, and then cut out the body.
 

Ok now on to the shoulders. Here we need to make a 2 axis shoulder that will allow a wide range of motion. First attach the horizontal axis servo and vertical axis servo together like in the picture, then you will glue the horizontal servo arm to the bottom of the body. Be careful to get the servos lined up as best you can to make controlling it easier and to make it more stable.

Now on to the legs. The legs are going to three degrees of freedom, two at the shoulder, and one at the knee. Now you have to decide how long you want the legs to be. Once the length of each segment cut them out. First past the second segment of each segment to the respective servos, and the third segment on to the servo arm. Now attach the other end of the second segment to the shoulder.

Now do steps three and four for all of the legs. Make sure that you have the spacing for the legs set so they can move freely.

Time to mount the electronics to the body. we need to attach the Arduino, servo board, and battery. attach the mounting nuts to the holes in the body and to the Arduino. Attach the servo board to the Arduino, and hook up the servos to it.. Find a good spot for the battery and use double sided tape.


Now the raspberry pi can be added whenever its ready. One of the best things about this design is that the pi and Arduino can be programed from one connection.

This came out really nice, I would use bigger servos though, they are very fragile. I would use metal gear servos as well. I put hot glue on the bottom of the feet, but I am going to put buttons or force sensors on the feet to help with balance. I am planning to add a range finder and a pi noir camera to it the help it with being autonomous. I'm really happy with how it came out, and I would like to hear any suggestions on this.

I will be making another instructable for the raspberry pi portion of this project later on.