This page is devoted to the development of my final project, a Quadruped Crawler. I will try my best to show the process of developing the robot.

My goal is to make a walking robot that will run on a battery and receive instructions via a radiolink from a computer.

At first I was afraid that I would have problems with the robot falling on one leg once it lifts it up to move it because of the non-uniform weight distribution, I thought of three different solutions which I will list here in the order of preference:

1. Have the robot shift its weight by tilting to one side before lifting up any one leg so that its weight does not rest on it. This way I can have the robot only use 4 legs.
2. Have the robot actuate its battery (actually move the heavy battery) so that it doesn´t fall when lifting one of the four legs.
3. Make the robot have 6 legs (not elegant and an overkill)

1st step: Motor control

Developing a motor controller board that can handle multiple servos and has an easy serial protocol. I developed this board about two weeks ago as a project in this class, here is the website: project 8.

• Video (WMV ~2.5Mb)

2nd step: Mechanical parts

Developing a base and all necessary mechanical parts. At first I built a base that assumed six legs and I used the lasercutter to make the parts out of acrylic.

• Base
  
• Upper leg
  
• Lower leg

Later, once I realized that I would be able to hav the robot only use four legs I built a smaller base out of alumnium using the waterjet cutter.

• Base

3nd step: Gait algorithms

As it turned out, I was able to lean the robot to the left and right when it takes steps such that I only need four legs and is able to shift its weight enough so it doesn´t fall when attempting to lift up a leg.

• A video of basic maneuvers while developing gait

Here is the version that uses the big acrylic base and is teathered both for power and communication.

• A video of some gait tests

4th step: Radio control

Now it is time to remove the teather off the robot and try to establish a radio link to the PC so that commands can be sent to it from a remote location.

The easiest way to accomplish this would be to buy a Bluetooth chip that has been designed to replace an RS-232 link but those go for about $50-100 bucks and are not very much in the spirit of our class.

We decided to use a Universal ISM band FSK transeiver from Integration and chose a carrier frequency of 433MHz.

• Datasheet for the IA4421-DS module
• Eagle board layout for the radio
• SPI comm link to the radio module (not working right now)

5th step: Sensing

I wanted my robot to be able to sense obstructions in its way so I used my ultrasonic range finder (a project from a previous week) to accomplish this.

• Project website

6th step: Integration

My robot is now ready !! Check out the video (Ástþór, thanks for the beats!)

• Video (~10Mb)