Robo-Glove

NASA is currently developing the next generation space suit for future missions, including the optimization of space suit gloves. When non-assisted space suit gloves are coupled to a pressurized suit and operated in a vacuum, they tend to limit the range of motion of an astronaut's hand to as little as 20% of normal range. Many of NASA's future missions will be in challenging environments where an astronauts hand dexterity will be critical for the success of NASA missions. Innovators at JSC have improved the performance on the second-generation, robotically assisted SSRG, to reduce exertion and improve the hand strength and dexterity of an astronaut in situ. The SSRGs system detects user finger movements using string potentiometers and contact with objects using force-sensitive resistors (FSRs). FSRs are imbedded in the distal and medial phalanges, palmar side of the glove. To move a finger, an actuator pulls a tendon through a Bowden Cable system which transfers mechanical pulling force of an inner cable relative to a hollow outer cable, like the brakes on a bicycle, as seen in the Figure below. An improved controller commands the new, more powerful linear actuator to drive tendon operation while minding custom controller parameters inputted through a digital editor tool. The Space Suit RoboGlove is at TRL 6 (system/subsystem model or prototype demonstrated in a relevant environment) and it is now available for licensing. Please note that NASA does not manufacture products itself for commercial sale.

Visual Perception System: Key to enabling humanoid robotics to perform dexterous tasks, R2’s visual perception system (U.S. Patent No. 8,244,402) – comprised of machine vision cameras, processors, and novel algorithms – allows robots to find, track, and measure objects automatically in their field of view. Tendon Tension Sensor: Unique tendon tensions sensors (U.S. Patent Nos. 8,371,177 & 8,056,423) are embedded in R2’s palms to enable granular force control of the fingers via a redundant network of tendons. R2’s tendons are coupled to, and used to actuate, the robot’s finger joints. Thus, tendon tension measurements provided by the sensor allow for the external loads experienced by its robotic fingers to be derived. Tactile System: R2’s hands feature an innovative tactile system that grant the robot a sense of touch (e.g., measurement of external contact forces, shear force, and slippage of objects held in the hand) – an important requirement for robots designed to perform complex tasks in an automated fashion. The tactile system is enabled by novel six degree of freedom (DoF) force torque sensors (U.S. Patent No. 7,784,363), which are integrated into the fingers at each phalange (14 per hand). A calibration system (U.S. Patent No. 8,265,792) ensures the sensors maintain high accuracy throughout operation. Contact State Estimation: A contact state estimation sensor (U.S. Patent No. 8,280,837), based on the use of a particle filter, enables R2 to perceive the location, orientation, and shape of objects when in contact with the robot’s hands (i.e., tracks hand-object state). The contact state estimation system leverages a novel motion model, which characterizes the motion of a robotic hand as it moves relative to an object of interest. Series Elastic Actuator (SEA) Sensing: R2’s SEAs achieve fine torque sensing at each of its joints without sacrificing strength or payload capacity. The robot uses two 19-bit absolute angular position sensors, calibrated using a novel technique (U.S. Patent No. 8,250,901), to measure the deflection of each spring in real time.

Technologies for Safe Workspace Control of Humanoid Robots: Safety is critical in scenarios where humans (e.g., factory workers or astronauts) are working in proximity to, or interacting with, R2. Methods for applying workspace limitations in velocity-controlled robotic mechanisms (U.S. Patent No. 8,676,382) and force or impedance-controlled robots (U.S. Patent No. 8,483,877) help to ensure such safety. Autonomous Control Systems for Humanoid Robotics: A multiple priority operation space impedance control system (U.S. Patent No. 8,170,718) provides arm control, including programmable Cartesian stiffness. An interactive robot control architecture (U.S. Patent Nos. 8,364,314, and 8,260,460, and 8,706,299), including a simple GUI, provides an interactive development and work environment that integrates sensor data and feedback generated by R2. An additional system selects and controls appropriate manipulators to perform grasping operations (U.S. Patent No. 8,483,882). Humanoid Robotic Health Management System: A diagnostics, prognostics, and health management system for human robotics (U.S. Patent No. 8,369,992) operates at all hardware and software levels of the robotic system, enabling system-wide observability, controllability, maintainability, scalability, and extensibility. Electromagnetic Motor Braking: Electromagnetic fail-safe brakes (U.S. Patent No. 8,067,909) allow for selective, reliable braking of robotic motors (e.g., brushless DC motors) to ensure safe and effective operation. Highly Durable Connector Pin: To address the high failure rate of connectors in robotic systems with flexible members, a highly durable connector pin (U.S. Patent No. 8,033,876) was developed. The pin increases durability of connectors that are frequently flexed – a condition that causes deformation and compromises connectivity.

NASA, GM, and Oceaneering approached the development of R2 from a dual use environment for both space and terrestrial application. NASA needed an astronaut assistant able to function in space and GM was looking for a robot that could function in an industrial setting. With this in mind, R2 was made with many capabilities that offer an enormous advantage in industrial environments. For example, the robot has the ability to retool and vary its tasks. Rather than a product moving from station to station on a conveyor with dozens of specialized robots performing unique tasks, R2 can handle several assembly steps at a single station, thereby reducing manufacturing floor space requirements and the need for multiple robots for the same activities. The robot can also be used in scenarios where dangerous chemicals, biological, or even nuclear materials are part of the manufacturing process. R2 uses stereovision to locate human teammates or tools and a navigation system. The robot was also designed with special torsional springs and position feedback to control fine motor movements in the hands and arms. R2's hands and arms sense weight and pressure and stop when they come in contact with someone or something. These force sensing capabilities make R2 safe to work side-by-side with people on an assembly line, assisting them in ergonomically challenging tasks or working independently. This NASA Technology is available for your company to license and develop into a commercial product. NASA does not manufacture products for commercial sale.

R2 uses brushless DC motors, harmonic drive gear reductions, and electromagnetic failsafe brakes as the building blocks for the powerful, torque-dense actuators in its human-scale, 5 DoF upper arms. Moreover, the use of series elastic actuators and novel tension sensing & control systems represent some of the most innovative technologies present in the humanoid robotic arms of R2. Series Elastic Actuators (SEAs): R2’s SEAs achieve fine torque sensing at each of its joints without sacrificing strength or payload capacity. Such capabilities are enabled through the development of several advanced technologies. Specifically, novel planar torsion springs (U.S. Patent No. 8,176,809) are integrated into each rotary series elastic actuator (U.S. Patent No. 8,291,788), while two absolute angular position sensors, calibrated using a novel technique (U.S. Patent No 8,250,901), measure the deflection of each spring. Force and Impedance Control Systems (U.S. Patent No. 8,525,460): These systems use position sensor signals for sending position data to an embedded processor that determines the positional orientation of the load relative to a motor shaft and its related torque on a string. A FPGA-based controller (U.S. Patent No. 8,442,684) provides a high-speed (10 KHz) control loop for the electric motor and gear reduction assembly present in R2 joints. Tension Sensing & Control of Tendon-Based Robotic Manipulators: NASA has also developed technologies to provide tension sensing & control of humanoid robotic arms. First, a tendon tension sensor (U.S. Patent No. 8,371,177) measures strain on tendons (strings) employed in robotic arms. A novel calibration system (U.S. Patent No. 8,412,378) calibrates the tendon tension sensors. Finally, joint space impedance control systems (U.S. Patent Nos. 8,170,718 & 8,060,250) provide closed-loop control of joint torques or joint impedances without inducing dynamic coupling between joints, as well as programmable Cartesian arm stiffness.