Archive for the ‘Cryospheric Research’ Category

Introducing Andy Hoffmaster and GROVER the rover

Post 1: Welcome to Engineering Boot Camp
Post 2: Introducing Andy Hoffmaster & GROVER the rover

Andrew Hoffmaster and GROVER, Assateague Island State Park, Md.

Andrew Hoffmaster and GROVER, Assateague State Park, Md.

Andrew (Andy) Hoffmaster is one of the dozens of interns working this summer in the Engineering Boot Camp at NASA’s Goddard Space Flight Center. He recently graduated from the Catholic University of America in Washington, D.C., with a degree in biomedical engineering

It’s Hoffmaster’s third year in Engineering Boot Camp. This year he has stepped up to a leadership role, supervising five different teams of interns who are working on a science robot called GROVER. In a time-honored NASA tradition, “GROVER” is a very impressive-sounding acronym: Goddard Remotely Operated Vehicle for Exploration and Research.

photo of grover rover on beach

GROVER on the beach.

GROVER, in a nutshell, is a solar-and-wind-powered, caterpillar-tracked rover that carries a ground-penetrating radar device. It is designed to roam alone for months at a time measuring the thickness of the Central Greenland Ice Sheet, which is about the size of Texas. “The problem with sending people is that they run out of food and fuel too fast,” explains “NASA Mike” Comberiati, who runs the internship.

Someday, GROVER will crawl across frigid Greenland at up to 3 mph, 10 hours per day, for 4 months. NASA Mike and his interns are working with NASA cryosphere researchers Lora Koenig and Hans-Peter Marshall on the project. (Koenig is based at Goddard; Marshall is at Boise State University in Idaho.

GROVER being unloaded.

GROVER being unloaded.

Hoffmaster and GROVER have spent a lot of time together, although in his first year  internship (2009), he didn’t work on GROVER at all. He designed and built the mechanical parts for a laser-scanning device on another robot, referred to as “the Mothership.” More on the Mothership in future posts, but you can take a quick look at her HERE.

GROVER 1 & 2
In his second internship season (2010), Hoffmaster started working on GROVER. He built the housing for the rover’s electronics. In January 2011, he accompanied Comberiati to McMurdo Station in Antarctica to help install and configure equipment to communicate with NOAA POES satellites.

Making tracks!

Making tracks!

GROVER 1 (shown in the video and images in this post) weighs about 700 pounds. Its solar panels and wind turbines — the spinning blades produce power when it’s cloudy — provide ample power. It has performed admirably in testing.

But GROVER 1 is too heavy and too big, and it takes too long and too much work to unload and assemble. This summer, the interns assigned to build a better GROVER.

GROVER 2.0 will be lighter and smaller. It will sport more efficient solar panels and a lower center of gravity to resist tip-overs in gusty Greenland winds. The rover will also gain software to allow it to operate without constant human monitoring, and to uplink data via the Iridium satellite network.

Also, GROVER 2 will be fabricated in three sections to enable rapid assembly by people wearing bulky cold-weather gloves. After all, standing around in the cold in Greenland can be a health hazard!

This, and more, will require the labor of five intern teams to design, build, and test the electrical components and systems (headed by Hoffmaster) and four mechanical teams (headed by senior intern Guillermo Diaz, a student at Tec de Monterrey in Mexico). It all has to happen in about 5 weeks’ time.

Last year’s crop of interns completed construction of GROVER 1, which today sits on the front lawn of Building 25 in Goddard’s wooded east Campus. The rover will serve this year as a test bed for some of GROVER 2’s new systems.

On the beach with GROVER
It was a chilly day, April 1, 2011. Hoffmaster and three other interns drove with NASA Mike down to Assateague State Park, with GROVER on a flatbed truck. While backing GROVER down the ramps onto the beach, they paused cautiously to check the rover’s orientation.

Then something weird happened, Hoffmaster says. One of the twin caterpillar tracks switched into full reverse and tipped GROVER off the ramps and onto the sand. Thankfully, the robot was unscathed except for a piece of bent metal.

The culprit: “anomalous cold bit.” To us non-specialists, that means that because of cold temperatures, the caterpillar track’s electronic controller sent an incorrect instruction. It’s just the sort of thing that can happen during the development of new technology, and the interns will work to solve it this summer.

On the beach, GROVER proved itself, with enough traction to drag Andy across the sand. Sand, it turns out, is close enough to snow (from GROVER’s point of view) to provide a decent simulation of the rover’s performance in Greenland. They tested it until 3:30 that afternoon and headed for home.

Andy says Engineering Boot Camp gave him valuable engineering insights and skills that he will be able to apply to his new job with Aretech in Dulles, Virginia, developing physical therapy equipment for rehabilitating stroke patients. He’ll work on a device called a “body weight support gait trainer.” It’s a harness on a motorized trolley track that supports patients safely as they re-learn how to walk after brain injury. “I took what I learned at Goddard and can apply it to human kinematics.”