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<i>Technologies for Safe Workspace Control of Humanoid Robots:</i> 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. <i>Autonomous Control Systems for Humanoid Robotics:</i> 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). <i>Humanoid Robotic Health Management System:</i> 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. <i>Electromagnetic Motor Braking:</i> 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. <i>Highly Durable Connector Pin:</i> 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.

The R2 hand and forearm assembly represents the cutting edge of humanoid robotics technologies. The highly modular design provides significant improvements over prior humanoid robotic hands, especially in the areas of strength, speed, sensing, and ability to approximate human grasps. <i>Hand, Finger, and Wrist Assembly Design:</i> The robotic humanoid lower arm design (U.S. Patent No. 9,505,134) includes novel robotic finger (U.S. Patent No. 8,562,049), thumb (U.S. Patent No. 8,424,941), and wrist (U.S. Patent No. 8,498,741) assemblies. <i>Actuation & Control System:</i> A novel finger actuation system (U.S. Patent No. 8,467,903) comprised of an actuator, tendon, conduit, tension sensor (U.S. Patent No. 8,371,177), and terminator is perhaps the primary enabling technology for R2s compact, high performance robotic hand. The actuation system is packaged in the wrist (U.S. Patent No. 8,401,700) and reduces the number of actuators, providing significant space savings. Control systems include methods for tensioning (U.S. Patent Nos. 8,412,376, 8,618,762, & 8,056,423) and controlling torque (U.S. Patent No. 8,565,918) of the tendon-driven robotic fingers. The finger actuation control system (U.S. Patent No. 8,489,239) can operate using force- or position-based control laws. <i>Tactile System:</i> R2s 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), three of which are integrated into the fingers (at the proximal, medial, and distal phalanges) and two in the thumb (medial and distal phalanges). A calibration system (U.S. Patent No. 8,265,792) ensures the sensors maintain high accuracy throughout operation. <i>Autonomous Grasping:</i> A novel grasp assist device (U.S. Patent No. 9,878,452 & 9,067,319) enables reliable, autonomous interaction with a broad range of objects (e.g., tools). A particle filter-based contact state estimation device (U.S. Patent No. 8,280,837) performs object localization and characterization.

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.