The Nomad is an outdoor roving robot built on the robot chassis kit from Servo City of the same name. It was initially built as an extension of the review I wrote of the chassis for Servo Magazine (which was published in the March 2015 issue). Check out that article for my experience building the chassis and my initial impressions. Here I will discuss more about the technology on board and plans for Nomad.
In its current state, at the time of this writing, Nomad is powered by a 12V sealed lead acid battery (SLA) which is tucked away in the center box along with the RoboClaw dual channel 15A motor controller and the RC receiver. The RC receiver was used to control Nomad while I was putting it through its paces for the review. Nomad is outfitted with six ultra sonic range finders (SR-04) for object detection and collision avoidance which are fed into an Arduino Uno through a custom shield built from a Seeed Studio Proto-Shield. It is also sporting a Samsung Galaxy S3 smartphone and a GoPro camera. The GoPro was originally mounted to capture footage for the demo video and the plan was to figure out how to capture the video output and use it for computer vision. However, this is proving to be a challenge. In order to capture the video I would have to configure the phone to log on to the GoPro’s wireless network and capture the stream from there. This will chew up a lot of the phone’s cycles and is probably more complicated than it needs to be. I have another plan.
I recently got a Raspberry Pi with the camera module and an Arduberry expansion board. By deploying the Pi as the vision processor I will be able to compartmentalize functionality. The Arduberry board will replace the Arduino Uno but still allow me to use the custom shield. In this way the Arduino will act as brain stem, communicating between the higher functioning systems, the motor controller, and the basic sensors. Meanwhile the Pi can focus its resources on capturing video and performing the analysis needed for effective robot vision. The Galaxy will leverage its ARM processor, superior memory, and on-board sensors to act as the primary processor. In addition, the Galaxy can be subscribed to a mobile data plan which will allow it to pull information from the Internet and post its progress on-line.
To help protect all of the electronics I will be building a shell to cover the robot. The power system will get an overhaul as well. The SLA will be replaced with a number of LiPo batteries and on-board chargers. An array of solar cells will be added to accommodate charging in the field and logic will be built in to manage power requirements and charge time.
What the whole package will allow me to do is build a pretty good roving robot with the intention of entering Magellan competitions. Magellan competitions are robotics challenges where autonomous robots must navigate between preset way-points for time. Often times the robot may be required to perform tasks or make contact with objects at the way-points without moving or damaging them. They also have to be able to deal with whatever terrain the course has to offer. All of these factors make for specific, real world challenges and a lot of fun.