Monday, January 05, 2015

My QuickBot test with IR sensors

By following the Coursera course, Control of Mobile Robots[1] by Dr. Magnus Egerstedt, I've built my first QuickBot in which the BeagleBone Black is the core.

The course had been closed in several months ago, but I didn't get enough leisure time (and proper mood... maybe...) to complete the robot until these weeks. The following photos show the QuickBot:
Front view of my QuickBot
Top view; the BBB is on the left side

The mess of wires between the chassis
What I have done so far is to test the sensors and motors with the help of the testing code qb_test written by Mike Kroutikov. Because I've used the Sharp GP2Y0A41SK0F IR sensors which are different from the ones assigned in the course, I am not sure whether the output is identical to that given in the comment of the test code. Therefore, after some tests, I decided to modify the test code for the IR sensors to show the detected distances in centimetres[3].

I searched and found some conversion formulas for Arduino[2]:


The trend of the output seemed right, but the absolute values were far from accurate. I might have to do some tests to find my own formula.

What I failed in the test was the communication between the host PC (running pysimiam) and the QuickBot's BBB (running quickbot_bbb). I have Wi-Fi adaptor connected to the BBB and it worked perfectly for accessing the internet, but I just couldn't connect the BBB wirelessly from my PC. I decided to postpone this part.

My next plans are:
  • To write some code to drive the motors with the IR readings as the reference;
  • to change the battery packs to the Li-Poly one.

[1] Without signing up the course, you may not be able to view the content. Here is the play list on YouTube: . It has only the video course, however.


[3] My modified code is here: