It's been a little while since I posted any updates. May and June were crazy busy and it was difficult to find time to work on Nomad and document the work. I know, another sad excuse. I will get better at this.
So, despite the schedule, there have been quite a few changes made on Nomad.
Nomad was stripped down to the frame and the Raspberry Pis removed along with their mounting plates. The Roboclaw, Arduino, sensor shield, and sensors were left in place for most of the rebuild, partially for sizing and placement concerns. Once this was done I was able to turn my attention to getting the Jetson board into the robot.
A new box was needed to house the Jetson development board. It was designed to follow the contours of the existing frame, including the ulttrasonic rangefinders, and extend out over the wheels. Extra space is needed to accomodate wiring and accessories such as the USB hub. The box was desinged to use 6-32 screws and square captured nuts to hold it all together. Once designed, it was cut out on the laser cutter at ATX Hackerspace.
Two exhaust fans were mounted towards the back to help manage heat and force air flow. The air flow is further aided by the fact the box is raised about an inch from the aluminum frame to allow enough space for the Arduino sensor shield and the sensor connectors. The Jetson board, itself, is raised another inch to help with this spacing and to allow room for cabling.
The box has several other components mounted to it for convenience. Next to one of the fans I've mounted the power switch and the power jack for when Nomad is on the bench. The power jack allows me to connect a 12vdc power supply to Nomad while I'm working on it so I don't need to run it off the batteries during development and testing of sensors, the camera, etc. In addition to the power related components I also brought some of the Jetson's ports outside the case. The WiFi antenas are mounted to the back of the box so these connectors needed to be moved. The HDMI port for the monitor has also been moved to the back of the box using an HDMI wall adapter from Home Depot.
The top plate of the box also has a couple extra features. The pan-tilt assembly for the camera is mounted toward the front of the top plate. Once the top plate is affixed to the box and secured, access to Nomad's internal workings is accomplished through a removable panel. This panel also has the mast supporting the Razor IMU from Sparkfun.
Since one of the purposes of Nomad is to promote interest in robotics and, frankly, to show off a little bit, the box is built with viewing ports. The sides and top panel have clear acrylic windows which allow people to see inside Nomad without having to open the box. The inside of the box is painted white and LED lighting has been added to illuminate the interior of the box. With that the public can view the workings of Nomad while still providing protection.
With the new box built and prepped it's time to start mounting all of the hardware. I'll cover that in the next post.