NASA’s Langley Research Center is developing a robotic arm with lightweight joints that provide a wide range of motion. The envisioned design provides users with a long reach and numerous degrees of freedom. The arm, ideal for use in aquatic environments or for manipulation of light terrestrial loads, consists of articulating booms connected by antagonistic cable tension elements. The arm elements are structurally efficient and lightweight, and support compact packaging. The inherent mechanical advantage provided by the tendon articulation allows the use of small, efficient motor systems. The manipulator can be scaled over a large range from 10 m (load-bearing arm) to over 1000 m (submersible or float-supported arm). Current efforts are focusing on a 15-m prototype and a 300-m subsystem to test the unique robotic architecture. NASA is seeking partners to assist with the development of its concept system for specific applications.
The lightweight and hyper-dexterous nature of the NASA-developed robotic arm is enabled by its tendon-articulated joints. Manipulator joints are actuated by capstans or winches located along the boom. This configuration offers significant mechanical advantage and improved efficiency over existing arms that use weighty gearboxes and motors. The arm joints have very high structural efficiency and significantly reduce manipulator mass while achieving a high level of joint stiffness. To further reduce weight while maintaining strength, stiff truss structures replace tubular links or booms between joints.
NASA has developed an algorithm to scale the arm based on tip load, reach, and tip deflection inputs for any given application. The design can be extended by the addition of articulating joints and degrees of freedom for improved arm dexterity. A prototype model of the joint is being fabricated, and range-of-motion tests are forthcoming. Required motor and controller architecture, sensors, hardware, and software systems are under development.
The arm provides a long reach for remote inspection or manipulation in inhospitable environments. It requires minimal storage space when packaged and can be easily transported. The design can be tailored for applications of varying reach, dexterity, or environmental requirements, and it has the capability to actively change component geometry during operation (e.g., extending or relocating links and spreader arms, etc.). An updated drive system is capable of reducing motor torques by an order-of-magnitude compared to the first-generation system.
This technology has potential application on Earth and in space. The Earthbound applications include ship-to-harbor, harbor-to-ship, or ship-to-ship docking; retractable covers and awnings; camera booms for filming operations; oil spill containment on water; floating barrier deployment and maneuvering; and subsea cable inspection and placement. The space applications include long-reach grappling, manipulation, capture, and mining of asteroids; spacecraft berthing operations; satellite servicing and repair operations; astronaut positioning; and in-space assembly and construction.