In the coming decades, NASA plans to send human crews back to the moon, build a space station in lunar orbit, establish a permanent base on the lunar surface, and—hopefully—send astronauts to Mars.
What could possibly go wrong?
No, seriously, what could go wrong and how would we fix it? That is the question a group of researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have been asking over the past four years as a part of a research institute to develop resilient and autonomous deep space and extraterrestrial habitations.
The Resilient ExtraTerrestrial Habitats institute (RETHi) is led by Purdue University, in partnership with SEAS, the University of Connecticut and the University of Texas at San Antonio. Its goal is to “design and operate resilient deep space habitats that can adapt, absorb and rapidly recover from expected and unexpected disruptions.”
Justin Werfel, Senior Research Fellow in Robotics at SEAS, is leading the team tasked with developing technologies to let autonomous robots repair or replace damaged components in a habitat.
“What happens if a meteorite breaches the habitat between missions, and the crew isn’t there to fix it,” asked Werfel. “Or if it happens during a crewed time, the astronauts may have their hands full with other emergencies. Likewise in more routine situations; there are a lot of regular maintenance tasks that take up valuable astronaut time, from replacing filters to cleaning things. You’d really like the habitat to be able to handle as much as possible on its own, which means robots doing that work.”
Since the project began in 2019, Werfel and the team, which includes Robert Wood, the Harry Lewis and Marlyn McGrath Professor of Engineering and Applied Sciences at SEAS, have developed new robotic arms and grippers, new systems to improve human-robot collaboration and new ways to design robot-friendly equipment.
Multifunctional tools
One of the biggest challenges in designing robots for these so-called SmartHabs is the multifunctionality needed for deep space habitation. Most industrial robots, such as those used to build cars or stock warehouses, are highly specialized and perform only a few specific tasks. But deep space habitats won’t have room for dozens of specialized robots. Instead, one or a few multifunctional robots will need to be able to perform many different tasks, including emergency repairs.
One project toward that end has been to develop multi-mode grippers that can change their shape to grasp different types of objects in different ways.
“Human hands can adapt to many functions, including those that need high precision, require high forces, or those that may benefit from compliance,” said Wood. “This design attempts to capture analogous adaptable behavior to increase the range of tasks possible with a single gripper.”
In a paper published in IEEE, Werfel and the team, which includes collaborators from the Harvard Graduate School of Design (HGSD) and Pusan National University in South Korea, developed a gripper with fingers made of so-called scissor links, which can be reconfigured to change the number of joints in the finger.
This gripper has three modes. In the first, the fingers are short and don’t bend, allowing them to strongly and securely grasp objects. In the second mode, the fingers gain a joint to let the gripper perform in-hand manipulation, allowing it to move and rotate objects without letting go of them. The last mode adds two more joints, allowing the fingers to passively adapt to the shape of an object and distribute contact pressure, which is useful for grasping irregularly shaped or delicate objects.
This paper was co-authored by Junghan Kwon, of Pusan National University; SEAS graduate students David Bombara and Clark Teeple; Joonhaeng Lee and Chuck Hoberman of HGSD; and Wood.
