In Fall of 2013-2014 school year, I took on the roles of Lead Project Manager and Captain for NYU’s Team Atlas. Team Atlas serves as a unique opportunity for both graduates and undergraduates of different engineering backgrounds to come together in a year long project to apply what they’ve learned in class in order to construct a large lunar robot. The robot must be able to mine and deposit regolith (a fine powdery soil commonly found on the moon) semi-autonomously and teams from all across the country travel to NASA Kennedy Space Center each year to compete in the competition. It’s a lot of fun and the competition is a blast.Above: This is a brief “midnight indoor test” we did demonstrating general mobility and basic teleop of the robot.
Our robot was unique in that our final design was extremely light at ~26 kilograms and also was notable because our primary digging mechanism was through our wheels. We ensured a light final weight by using carbon fiber parts and emphasized risky but emerging new technologies like 3D printing while other teams did not. In fact, all of our wheels were entirely 3D printed by our uniquely gifted mechanical engineering team. Since a single wheel was bigger than the working space used by our 3D printer, the wheels were designed to be printed in 6 smaller pieces, then interlocked together like a puzzle in order to make one large wheel of the correct size. The wheels drive normally in one direction, and when driven in reverse will scoop up lunar soil which then slides through a hole in the tread through the inside of the wheel, and then out through a special slot near the axle down into a centralized collection bin.
My primary duty was to make sure the project remained on schedule and that things get built, however on a large scale year long multi-disciplinary project such as this, you find that you end up wearing as many hats as the team requires each day in the lab. As an electrical and computer engineering major, I made significant contributions to both the computer and electrical design of the robot. This included primary oversight of the electrical design on the robot, as well as spending quite a bit of time with our computer science team helping to implement an effective communications protocol and making sure the robot was safe and under control.
For computer hardware, we used an Arduino Mega as the primary robot CPU. The Arduino communicated via a special WiFi chip with a laptop running a custom LabVIEW virtual instrument panel located in a NASA hauler 50 feet away. We chose to use these programs based on ease of use and a large existing support base they already had on the internet. We operated the robot with a wired Xbox 360 controller which allowed us to both drive and control the Pully mechanism, as well as both actuators which controlled the lifting of the robot’s collection bucket.
We wrote Labview programs to give us live feedback on how far the actuators were extended, as well as power consumption and battery life indicators. Behind the scenes, the labview program was receiving and parsing messages from the robot, and packaging and sending out commands to be received. Everything was timed via a heartbeat system and watchdog timer, letting both the robot and the control panel know that communications had been lost if either party did not hear an acknowledgment after half a second or so. If the robot lost communication with the control panel, it would shut down it’s motors and enter a fail safe mode, attempting to reconnect with the LabVIEW host control panel. Likewise, the labview panel would attempt to reconnect with the robot automatically if the watchdog ever fired.
Each wheel had a current sensor allowing us to tell if a wheel was stalled or stuck in the sand. All of this data was captured in real time and saved in log files for later inspection.
A large portion of the robot was 3D printed, which was an early design choice based on our lack of access to a full machine shop (which was under construction). This saved us quite a bit of weight in the final design, but forced us to get creative when we wanted to build a larger structure (such as our wheels) using the limited printable space which the Makerbot could allow. To overcome this problem, we split the wheel design up into 6 smaller pieces, and designed them fit together like a puzzle. Because our robot used it’s wheels to dig while driving, you can imagine the complexity of this final cad design. I’m quite proud of the mechanical team for the work they put in on those wheels and what I felt was a great highlight on our robot and really innovative design choice. The rest of the robot used carbon fiber tubes held together with custom 3D printed locking corner pieces which also served to hide all of the electrical wiring from dust in the Arena.
NYU Robot Source Code | (Arduino)
by Nicholas Reid and Eason Smith
Command and Control VI | (LabVIEW)
by Eason Smith