3pi pololu robot 3rd experiment

This time we decided to check the precision we can obtain measuring distances with the Pololu 3pi.
There is a function called encoders_get_counts_m1 in the AVR Library available on 3pi stuff. The function returns the counts of motor 1, and declares that the value of the distance from the start point is near 3 mm/count. So, we coded 3pi to follow a (straight) line, stopping after what should be 10 cm forward and wait for button B pressure, and so on, until the end of the line.
We measured each stop with a rule, and got the values (in centimeters):
7.8 - 8.5 - 8.5 - 7.9 - 7.9 - 9.2 - 7.6 - 7.5.
The bigger difference is 9.2 - 7.5 = 1.7 cm. This points to a possible error of aprox. 18.4% on the measurement. But it is not conclusive yet. We must check if there are no external influences, as the pressure of the button, that can be changing the results.

3pi pololu robot 2nd experiment

Next (see before 3pi pololu robot 1st experiment) we decided to make 3pi follow a given path from point A to point B.
We inserted an array of directions into the C code. Each time 3pi find a diversion it consumes a direction from the array and applies it.



This research activity is part of Grupo de Tecnologia e Desenvolvimento de Sistemas Computacionais.

3pi pololu robot 1st experiment

The 3pi pololu mobile robot is a low price device that allows a lot of experiments.

Me and my friend Fabio decided to investigate the possibilities.

This is the result of our first try. (we are programming the bot trough my netbook + ubuntu 9.10) using the usb cable that comes with it.

Language is C.

Following a random path.



This research activity is part of Grupo de Tecnologia e Desenvolvimento de Sistemas Computacionais.