Coding Like Curiosity – Part 2: Building a Robot

Final form for CurioDuino

In the last post I talked about learning to code in Arduino. This time I would like to talk about hardware. The pieces of hardware that I will be using have already been listed in the previous segment, but I will list them again here.

1. Arduino Uno R3

2. Pololu Zumo Shield with Robot and Reflectance Array

3. Three Sharp Digital Distance Sensors 5cm

4. Adafruit Bluefruit EZ Link Shield with Stacking Headers

Note: The Adafruit EZ Link Shield is only being used for communication currently because the board does not work well for reprogramming across bluetooth yet. (But, Adafruit is still working on it!)

EDIT (4/19/14): Adafruit has fixed their EZ-link!

For reference, here’s a pdf of the Uno board with all of the pins that are in use.

CurioDuino Pin-out

Let’s put CurioDuino together.

The first step is to purchase the ZumoBot chassis and assemble it, along with the Zumo Sensor Array from Pololu. If you read the above pdf carefully, you would notice that is necessary to cut traces between the four inside sensors of the array. Pololu shows how to accomplish this near the bottom of this page: http://www.pololu.com/docs/0J57/2.c

The next step is to get three of the 5cm obstacle sensors listed above. These  will be put into place by soldering using 3 of the 3-pin female adapters into the front expansion of the ZumoShield. The pins that are used for these are listed in the pdf above. There may some confusion with this step. It is truly up to the builder to decide how these sensors will be attached. As long as the data pin is connected to the correct pin shown above, all the code will work correctly. I used a combination of right-angle pins and wire to attach these sensors to the front of CurioDuino.

Once these are in place, slide the the Adafruit Bluefruit EZ Link shield with stacking headers into the pins of the ZumoShield.  Lastly, place the the Arduino Uno on top of the EZ Link. At this point, you have a fully assembled CurioDuino. All that is left is to upload the code to the Uno. Before doing this, ensure that the switch on the front of the EZ-link shield is set to “soft serial”.

All of the code is now available: http://github.com/davidskeck

There are three repositories (which all begin with CurioDuino) which contain everything, including the GUI. Before running the GUI, ensure that the constant titled PORT_NUMBER is set to the appropriate port for your project. Note that this project does not require bluetooth, but most cable solutions will limit the function of CurioDuino.

The next entry will focus on the software itself and the Real-Time operating system that it runs in.

Thank you for reading!

Truly Curious: Examining the Mars Science Laboratory Software Development Process

Lego Curiosity Set 

Another project update is currently being drafted, but I wanted to post a quick update with a paper I wrote recently. It details the software development process for the Mars Science Laboratory. I find it truly fascinating, and I hope you do too.

Here’s the link: MSL Software PDF

Coding like Curiosity: Introduction

Mars Rover Curiosity, Right Side View (Photo credit: Wikipedia)

Real-time operating systems have fascinated me since before I even knew what they were. The first real-time application that really made me stop and think was the Curiosity’s (or Mars Science Laboratory’s) software platform. One set of applications are responsible for controlling everything the rover can accomplish. This huge amount of responsibility is handled by a strictly scheduled operating system called a real-time operating system (RTOS). To learn more about how to create critical software for these types of systems, I have decided to adopt some of the software architectural principles, as described by Ben Cichy [0], in a much (MUCH) smaller rover project of my own.

I am going to create a software platform for an Arduino powered robot that will run on an RTOS and be separated into independent modules just like the Curiosity flight software. It will communicate with my laptop wirelessly to provide log details and accept basic commands. The robot itself will be almost entirely autonomous, utilizing an infrared sensor array to detect platform edges and another pair of infrared detectors to avoid obstacles. I’ll be using the Arduino Uno and only have about 32KB for the entire software, including the RTOS libraries. As such, I plan to use the nilRTOS libraries, which were derived from the ChibiOS and are extremely small and lightweight [1].

This blog will be updated as the project progresses. I hope to have it all completed by May 2014. I’ll update with a parts list in the next segment in case any one would like to try a project of their own.

       0. Cichy, B. (2010). The Evolution of the Mars Science Laboratory Flight Software. 2010 Workshop on Spacecraft Flight Software. Lecture conducted from California Institute of Technology. Pasadena, CA

       1.  https://code.google.com/p/rtoslibs/