Drone Following #6: Buying the right sensor

I'm having a hard time choosing which sensor to buy for the Drone following project. It's just as much as a mathematical question as it is a computational one. Let me put it to you this way, an Accelerometer is associated with acceleration, and a Gyrometer is associated with velocity. If you understand the calculus relationships there, you can interpolate "the next integral up" (velocity from acceleration, position from velocity, etc.), but it comes with a fair amount of error.

What we need from this project is a way to detect a change in rotation from the person, as well as a change on the two dimensional plane. This could be done by mapping the person's theoretical position, but again, even with the velocity and acceleration information, it can get kind of scary. Thankfully, the angular velocity of the person rotating can easily be extracted with a gyrometer, but that leaves the more difficult question... what about movement?

An important thing to consider is also how you plan to implement the system. You could do it with a position-tracking system, or you could "take things down a notch" and think in terms of velocity. I chose the latter, after thinking back to my teleoperation node for the Pioneer. Everything you see the joystick doing is actually "telling" the robot to change it's velocity in one direction (with some scaling). That being said, I think the same could be done for this project. ROS communicates messages quick enough that, as long as things didn't get dicey, the Drone could follow the person's velocity, or at least I think.

This kind of ambiguity doesn't leave me in a good place to buy some equipment. Thankfully, since the consummation of my project and my Electronics course's project has finally occurred, I can lean on the department to buy a nice sensor (that they will own for other student projects hereafter) at no risk or expense to me. Therefore we went with a complex 9 DOF stick from sparkfun. After all, you can just ignore the aspects you don't need until you get to that point. And who knows, maybe if this goes well, this chip could be the kind of thing we'd want for the head tracking, and then maybe just a simple one-axis gyro on the back.

I imagine it'll be a little bit before it gets here, so I'll spend more quality time with my Drone. It'd be a blast to get it configured with ROS!