The first steps

Starting up:
Participants: Johan & Jakob
Date: 30/9-2010
Duration: 3 Hours
Goal: Construct a segway and make it balance.


The Inner Ear
As the standard Lego kits does not contain a gyroscope sensor to monitor the robots tilt, we took the inspiration from the exercise sheet and used the light sensor to determine in which direction the robot is currently falling.
This brings all the usual trials and tribulations of using the light sensor, susceptibility to the environment, both external lightsources as well as the texture and color of the surface on which we tried to make the Failbot balance. 

Knowing which way is up
Similarly to the code handed out we start with an initial calibration, where we obtain the light sensor value representing the desired state, the robot in balance. When the robot tilts the light sensor moves closer or further away from the surface, and we can thusly use this value to compute which way we want the motors to turn.
Heavily inspired by the handout we used a similar PID scheme to avoid overshooting too much.




Standing Tall
After a bunch of failures of epic proportions, mostly the Failbot seemed to make an exhaustive search through the space of possible ways to fall, tilt and run off tables, we finally got the Failbot to keep balancing a few seconds, there was much rejoicing. One very pratical issue is that it has been very hard to set a prober initial state due to the fact that poorly constructed lego robots might not be very well balanced. The robot is programmed such that it cannot balance better than the initial state it is supplied with. An improvement could be using the gyroscope sensor that can be obtained, beyond being a better sensor for the task, it also gives the possibility of a decent calibration. If the robot is placed lying down, one could use this value to obtain a initial state ( perpendicular to this  state ) and balance with that in mind. If one used another light sensor on the opposite side of the robot, one might also be able to better balance.