Waiting

As of now I am just waiting and unable to make any progress until more supplies come in. Its pretty lame having to put a halt on the project for now, but come April I should be back in action. I'm still continuing to work on some more technical aspects such as gait sequences and inverse kinematics, but until I can get the robot assembled I can only virtually simulate how the programming may work. 


That's about it for now. 

Servos!

So I didn't make too much progress last week, but Wednesday, the servos came in the mail!

I got them hooked up and was able to get them to interface correctly with the arduino. The servos communicate at full duplex but the arduino is only capable of half duplex via UART, therefore a tri-state buffer was required. The servos are also require 7-12V so I needed a way to power them separately from the arduino. An arduino can be powered at a this voltage as well, but it will be easier down the line to have it running on 3.3 or 5V.

 

 I didn't do much more than get the servos to move last week, but hey... its better than nothing.

More modeling...

I'm still working on the model in Inventor and even though it may not look like it, I accomplished quite a bit over the weekend.  Before I go on, I'll show you the anatomy of a leg with some labels in case you don't really know the terms. Take a look at this picture of a leg used commonly on quadropods and hexapods sold by Trossen Robotics. You can see how each leg is split into a coxa, femur, and tibia. And how each joint in each leg has it's own servo to control its position.

Now onto the update:

Here's what I've got at this point. I now have attached the femurs as well as the tibia servos, which actually required a small amount of math (a couple torque calculations) to get the proportions correct. So as you can see, at this point I still need to design a tibia and possibly a foot to stick on the end of it. I've intentionally designed the legs so that they will hopefully be able to fold up and into the body while still leaving plenty of room for all of the electronics to live. 

I think I am going to hold off on finishing the legs this week and instead get a bit of the programming started. The servos won't be delivered for a little while (opted for some slow shipping from South Korea...) but the parts required to interface them with the arduino should be here tomorrow and I hope to at least be able to get all of the required libraries in order so that I can get the servos moving right when they arrive. I also need to plan out where I will put all of the electronics, and measure a few components so I can get an accurate representation of them into the 3D model.

Making some progress with the 3D model

I had to get a schedule together to register for classes this morning which was a nightmare... but I was able to get some more work done in inventor last night. I was even impressed with how nice it is starting to look.

Eight of the servos are now in place and both the top and bottom halves of the body are done. I even tossed all of the bolts in there to make it look a bit cooler.

Beginnings of a 3D Model

The robot will have four evenly spaced legs with 3 directions of freedom each (12 servos), it will use an Arduino Mega 1280 for brains, and will be powered by a small LiPo battery.

The design is based off of both commercial quadrupod robot designs as well as video games and science fiction. I'm not entirely sure what I want it to look like yet, but I am aiming for a much more mechanical look rather than an organic one. 

I am using Autodesk Inventor 2012 to model the robot and I started working on it last night. 
You can see my progress below...

So far I have only finished a preliminary model of the top half of the robot's body.

I highlighted one of the pieces with my mouse and that is why it is white. The top of the body actually consists of 4 identical pieces to make up the whole thing. I had to split it into 4 so that it will fit within the output area of my 3D printer... (glad I thought of that before trying to print). 

I will have to design some extra pieces to attach the 4 parts, and the Arduino will most likely not be placed where it is currently. ... Looks like I have my work cut out for me tonight. Hopefully I can have the first iteration of the entire body finished by Monday.

Introduction

So I'm a student at Drexel and I've been on co-op since September. Working can be dull, but at least I have plenty of free time and no homework to worry about. I wanted to use this extra time to work on some sort of geeky project but I couldn't really think of what to do...

I avoided anything related to robotics at first because I knew that I didn't have the resources or cash to create anything that wasn't thrown together with cheap hobby servos and popsicle sticks. I also felt that no matter what sort of robot I built, it would serve no practical purpose other than educating myself while working on it.

I never really got around to deciding upon a project and co-op was ending soon... I felt like a bum for wasting all that time. Then I found Makibox, the cheapest 3D printer I've ever seen. I almost bought a RepRap, then, a Printrbot, and finally as the price dropped more with the announcement of the Makibox I just couldn't say no. (I think I was the 6th person to back the project) Sure it is small, but Ive got faith in Jon Buford and can't wait for it to arrive in the mail. The funding just ended yesterday and reached over 200% of the goal and almost $100,000. 


After throwing down the cash for a small 3D printer, I ran into a predicament... what was I going to print?! I've had plenty of experience modeling and can really design and make anything that will fit into the printer's output area. Then I went back to thinking about robots again. Did some research. Left it alone. Did some more research. Thought some more. Left it alone. 

Then weeks later after getting frustrated with myself. It was a Friday at 3am, and I I bought 12 AX-12+ servos from Dynamixel. These things are priced around $45 but I was able to get them used for much cheaper.

I had decided to build a quadruped robot...      That's where this blog really starts.

Hello!

Hello!  - I decided to create this blog after recently starting a new robotics project in my free time. I originally only really wanted to keep a log of my progress, but I figured writing a few sentences after making some progress and tossing in a few pictures wouldn't be too hard...