Added the kinect

I finally soldered and installed the kinect to the front of the robot. 

The kinect boasts an impressive array of sensors including an depth camera, RGB camera and microphones. My intention is to use the kinect for SLAM and maybe teleoperation. The microphone would be able to listen to commands such as "move forward". Technically it can also be used for a bunch of fancy stuff like gesture recognition, since its original purpose was to be a gaming console that tracks player's movements.

Naturally I've had to elevate the LIDAR so that the kinect isn't blocking the laser. This is not ideal because now the lidar can't detect objects that are below a height of 25 cm. So its going to have a hard time detecting the small stuff I might have on my floor. This limitation makes it worthwhile for me to learn computer vision and use the kinect camera for object detection.

Adding URDF

So now that I have a whole bunch of sensors on the robot it's time to talk about transforms. 

Transforms are the relationships between different frames of reference on the robot. For example the center of the robot could be 5 cm off the ground, but the laser scanner is 10 cm off the ground. 

So your transform would be ( 0 0 5) to indicate that it is 5 cm up in the z direction (the convention is x y z).

However as you can imagine it gets messy trying to keep track of all of the transforms as the robot grows in complexity. What can end up happening is that you have transforms tucked away in different files, and its not obvious where to find them if you need to change one. 

Enter URDF!

URDF stands for Unified Robot Description Format and it is used to create a visual model of the robot as well as describe the relationships between links. Essentially it is an XML file with some dimensions and other values. The great thing about it is that you can use macros to make it really efficient to specify the details and have one central spot to edit the robot characteristics.

Recently I created my own URDF file to describe my robot. What I need to do next is to connect it with a robot state publisher that will publish the transforms for me.