MIT's Crab-Inspired Robot HERMITS Can Dock with "Mechanical Shells" for a Variety of Tasks

A team of roboticists at MIT's Media Lab have detailed Project HERMITS, an effort to produce 3D-printable "mechanical shells" to give robotic systems modular "tangible user interfaces" they can pick up and discard at will — inspired by the hermit crab and its disposable shell.

"Project HERMITS explores a way to greatly advance the versatility of Robotic Tangible Interfaces," the team explains of its work. "Inspired by hermit crabs, we designed a modular system for table-top wheeled robots to dock to passive attachment modules, defined as 'mechanical shells.' Different types of mechanical shells can uniquely extend and convert the motion of robots with embedded mechanisms, so that, as a whole architecture, the system can offer a variety of interactive functionality by self-reconfiguration. We envision this novel interactive architecture to bring a rich application space including physical space organization, digital data physicalization, and entertainment and storytelling systems."

"The general approach in HERMITS expands how physical interfaces and computers in our daily life can adapt and reconfigure for user interactions with passive attachments. We are in the age where robotic systems are emerging in our living space (e.g. robotic vacuum cleaner, drones). The idea presented in HERMITS has greater implications beyond our prototype, where everyday robotic systems may gain a significant amount of functionality, expressivity, and interactivity by switching mechanical shells."

To prove the concept, the researchers set about creating a range of mechanical shells designed to give the TUI robots a range of interfaces: A joystick, a knob, a lift interface, a "rotation accumulation shell," a traffic light, car- and bus-inspired vehicle shells, a fan, a robotic gripper, a rotating arrow, a shell capable of vertical motion, a two-degrees-of-freedom (2DoF) rotational shell, a "Mad Hatter" shell with matching "Grown Up Alice" and "White Rabbit" shell, and the core self-propelled robot — itself a shell which sits over an off-the-shelf toio robot body - which docks with and discards the shells on demand.

Some of the shells are simple 3D printed, including 3D-printed optical paths or add-on optical fibres; others, like the gripper shell, included gears taken from LEGO sets to speed the prototyping. Each shell was also given markers for augmented reality tracking, allowing a central control system based on a Raspberry Pi single-board computer to identify each shell and its location on the test area.

The team has published its paper under open access terms as part of the UIST'20 conference, with full details available on the MIT website; it is also making the Python-based Swarm UI interaction platform, the docking modification for the toio robot, and 3D models of the shells available as open source.