NASA Jet Propulsion Laboratory’s Mars rovers have a special place in my heart. I loved seeing pictures of Sojourner nuzzling up to rocks, and I still wonder whether it managed to drive around the Pathfinder lander after contact was lost. Spirit going silent was heartbreaking, and Opportunity continues to inspire so far beyond its expected lifetime, even as a dust storm threatens to starve it to death. And I particularly remember thinking how insane it was that Curiosity was going to drop onto the surface from a hovering robotic sky crane (!), and then being entirely overwhelmed to watch it happen flawlessly from the media room at JPL.
I’m not the only person who thinks that JPL’s rovers are incredible, and other rover fans have been pestering the roboticists at JPL for a cute little rover that can be built at home. JPL has been working on this for a little bit, and they’ve just announced the end product of their Open Source Rover project, and it’s “space robots for everyone!”
The Open Source Rover (OSR) was designed at JPL by a very small team: just two student interns and a JPL project lead, plus a bunch of help from experienced JPL robotics engineers. The goal was to make something accessible and affordable, since a previous education outreach rover that JPL had come up with (called ROV-E) was super popular but also cost over US $30,000. The goal with OSR was to decrease the cost an order of magnitude, while keeping it useful and compelling and easy to build, all in just 10 weeks.
They were successful, of course, coming up with a design that could be built completely from commercial off-the-shelf parts by anyone with $2.5k to spare. OSR’s drive system is modeled after the Curiosity rover, with six independently steerable wheels mounted on an obstacle-conquering rocker-bogie suspension. The face-mounted laser drill has been replaced with a programmable screen, in a necessary but rather disappointing compromise towards safety, and while there’s no built-in autonomy, JPL is doing its best to encourage community collaboration towards additional features in both hardware and software.
JPL estimates that it’ll take something like 200 person-hours to build an OSR, and while machine tools would be helpful, all you really need is a drill, dremel, soldering iron, a few other simple tools, basic familiarity with Linux and Python, and maybe a friend or two who knows something about safety if you’ve never done something like this before. The documentation (all on GitHub) looks to be pretty comprehensive, and there’s even a forum where the JPL folks are answering questions. We even managed to get one of them to answer our questions—we spoke with Mik Cox, who leads the Internet of Things team at NASA JPL and was the project lead for the Open Source Rover, over email.
IEEE Spectrum: What made you decide to develop the Open Source Rover? Where did this project come from, and what do the people involved do at JPL?
Mik Cox: The Open Source Rover was loosely based on a JPL educational outreach rover called ROV-E (Remotely operated vehicle for education) which went to museums, schools, and events to get people excited about robotics and space exploration. People regularly asked “can you give us the design so we can build our own”, but ROV-E was a little complicated and expensive to put together. We wanted to release a new rover which could be built for less than $2,500 by a team of high school students; this new rover is the Open Source Rover.
We hope that by releasing the plans for this rover we inspire the next generation of engineers, roboticists, and scientists to get involved by building their own mini Mars rover! I was the project manager on the Open Source Rover, but my regular role at JPL is as a data scientist and team lead for Internet of Things. I led two summer students for 10 weeks who designed, built, and documented the rover. One of them (Eric Junkins) was hired at JPL full-time and now helps our Prototype Robotics group. The other (Olivia Lofaro) is still in school and is now interning at Google X.
Can you describe how you developed the rover’s design? What were your priorities, and how different was the final design from what you first conceptualized?
The hard requirements for the rover were very few:
- Rocker-bogie suspension system similar to that on all Mars rovers
- 6-wheel drive and corner steering similar to that on all Mars rovers
- Composed of entirely consumer off-the-shelf parts or 3D-printed components
- Total cost of less than $2,500
- Expandability so others can add additional hardware and software (cameras, sensors, robotic arms, anything!)
- Personable, “cute” appearance
Our very first iteration was based on PVC pipe and 3D-printed joints. We scrapped that design after engineers expressed concerns about the robustness of a robot built with those materials. A secondary design moved to aluminum U-channels with common mounting holes, but the geometry of the “legs” was inefficient for climbing. The third and final iteration lowered the body substantially and optimized the “leg” geometry for climbing, allowing the rover to conquer much more aggressive obstacles. All three of these iterations took place in about 6 weeks.
Relative to some other robotics projects targeted at high school students, this one looks a bit intimidating. How would you introduce it to students with no robotics experience in a way that would give them confidence that it’s something they can do?
Our project was always intended for high school and up, and we’ve created our very detailed instruction set with this in mind. The instructions detail every step of building the robot, and not only how to put the robot together, but also why we made the engineering decisions we did. Every skill that’s necessary for building this rover (soldering, basic machining, electronics debugging, etc) is listed and we provide some links for tutorials around the Internet that we found helpful for learning these skills. In addition, we’ve tested our documentation by building the robot with multiple high school teams who had no previous robotics experience. All of the teams that have undertaken this project have been able to successfully build this rover. This rover is meant to help teach a number of the critical aspects of robotics: mechanical engineering, CAD/fabrication, electrical engineering, and software development. This combination may look intimidating, but many existing robotics projects may not give as much experience across all of these areas.
What are you hoping people will do with the rover once it’s built? What kinds of upgrades might be cool?
We hope that people expand on the rover’s capabilities and contribute those additions back to the community! We’d love to see improvements that bring down the cost of the rover while maintaining the same suspension system and drive capabilities of the Mars rovers. In addition, we’re hoping that people build on the rover’s capabilities by adding things like cameras, accelerometers, sensors and science packages, robotic arms, solar panels, new ways to control the rover, and anything else they can think of!
After building the rover, how would you recommend students continue in robotics, if (say) they want to work at JPL?
The best step you can make is to get involved and keep on getting practice by building neat things! We are excited about the number of robotics teams and groups that are popping up all over the world and we’re thrilled that the field of robotics is becoming so much easier to enter. JPL also has many internship opportunities, especially in the summer. We’re always looking for the next generation of explorers and builders.[ JPL ]