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Quick-connect fastener actuated by simple motion of hexagonal wrench. Enables assembly of truss by heavily gloved technician or by robot. Originally designed for use by Astronaut or robot assembling a truss in outer space, fastener also adapts to various connection applications requiring quick assembly or disassembly.
Vector-algebra method developed for extracting Denavit-Hartenberg parameters for any assembled robot arm. Method for extracting relative joint geometry of robot arms useful to researchers who need data for existing robot arms for either validation of mathematical models or for studies involving actual control of these devices. Method, does not require robot arm to be disassembled, also useful in recalibration of misalined or bent robot arm and becomes useful industrial procedure. Merit of method is errors not propagated.
Space Technology Mission Directorate, Game Changing Development Program: Precision Assembled Space Structure (PASS) annual review slides. PASS is an autonomous robotic assembly project with an emphasis on high-precision, high-performance large assembled structures.
A unique facility, the Automated Structures Research Laboratory, is being used to investigate robotic assembly of truss structures. A special-purpose end-effector is used to assemble structural elements into an eight meter diameter structure. To expand the capabilities of the facility to include construction of structures with curved surfaces from straight structural elements of different lengths, a new end-effector has been designed and fabricated. This end-effector contains an integrated microprocessor to monitor actuator operations through sensor feedback. This paper provides an overview of the automated assembly tasks required by this end-effector and a description of the new end-effector's hardware and control software.
The Automated Structures Assembly Laboratory is a unique facility at NASA Langley Research Center used to investigate the robotic assembly of truss structures. Two special-purpose end-effectors have been used to assemble 102 truss members and 12 panels into an 8-meter diameter structure. One end-effector is dedicated to truss member insertion, while a second end-effector is used to install panels. Until recently, the robot motions required to construct the structure were developed iteratively using the facility hardware. Recent work at Langley has resulted in a compact machine vision system capable of providing position information relative to targets on the structure. Use of the vision system to guide the robot from an approach point 10 to 18 inches from the structure, offsetting model inaccuracies, permits robot motion based on calculated points as a first step toward use of preplanned paths from an automated path planner. This paper presents recent work at Langley highlighting the application of the machine vision system during truss member insertion.
Robotic assembly operations such as mating and fastening of parts are more successful if the robot manipulator compliance can be controlled so that various coordinates are free to comply with external constraints. This paper presents the design of a hybrid controller to provide active compliance to a six-degree-of-freedom robot built at NASA/GSFC using force and position feedback. Simulation results of a 2 degree-of-freedom model is presented and discussed.
To meet the needs of future deep space exploration, NASA is interested in large-scale hardware systems in the agency’s thrust areas of solar power, communications, habitats and science interests. Scalable in-space assembly of physical systems is critical to massless exploration and in-space reliance goals. The ARMADAS project demonstrates the autonomous assembly of digital materials and structures. This provides automation technologies with potential for meeting long duration and deep space infrastructure needs, such as construction and maintenance of long duration spaceport, surface infrastructure, and habitat scale systems. Project demonstrations to date include a system that can fit into a small satellite-sized payload, which automatically assembles into primary structures, such as a small habitat module or array/antenna, using onboard robotic assemblers.
This paper presents the design and development of a transport and placement robot that demonstrates autonomous assembly of structural building blocks. The robots are intended to serve as a critical component of automated structural assembly and maintenance systems. The Scaling Omni-directional Lattice Locomoting Explorer (SOLL-E) uses a 5-DoF bipedal inchworm locomotion architecture with locking foot and cargo grippers. The locomotion system employs large magnet gap diameter BLDC motors with moderate timing belt gearing for primary joints, and DC planetary gearmotors for turning. Foot and cargo grippers are identical, with servo-actuated locking mechanisms. Three modular controller boards are used to control these actuators in real-time, with command and telemetry data transferred between the server and each controller board via WiFi. Functionality and performance were evaluated in a ground demonstration.
The next generation large aperture UV/Optical space telescope will need a diameter substantially larger than even that of JWST in order to address some of the most compelling unanswered scientific quests. These quests include understanding the earliest phases of the Universe and detecting life on exo-planets by studying spectra of their atmospheres. Such 8-16 meter telescopes face severe challenges in terms of cost and complexity and are unlikely to be affordable unless a new paradigm is adopted for their design and construction. The conventional approach is to use monolithic or preassembled segmented mirrors requiring complicated and risky deployments and relying on future heavy-lift vehicles, large fairings and complex geometry. The new paradigm is to launch component modules on relatively small vehicles and then perform in-orbit robotic assembly of those modules. The Optical Testbed and Integration on ISS eXperiment (OpTIIX) is designed to demonstrate, at low cost by leveraging the infrastructure provided by ISS, telescope assembly technologies and end-to-end optical system technologies. The use of ISS as a testbed permits the concentration of resources on reducing the technical risks associated with robotically integrating the components. These include laser metrology and wavefront sensing and control (WFS&C) systems, an imaging instrument, lightweight, low-cost deformable primary mirror segments and the secondary mirror. These elements are then aligned to a diffraction-limited optical system in space. The capability to assemble the optical system and remove and replace components via the existing ISS robotic systems like the Special Purpose Dexterous Manipulator (SPDM), or by the ISS flight crew, allows for future experimentation, as well as repair.
The Tall Lunar Tower project at the NASA Langley Research Center is focused on the design, modeling, fabrication, and testing of a supervised autonomously assembly engineering development unit for tall lunar towers. The lunar south pole environment poses many challenges for robotic assembly of the tall tower, particularly to computer vision camera systems due to a high-contrast lighting environment. This paper will present an Unreal Engine 5 video game engine Lunar South Pole Lighting Testbed to simulate realistic lunar lighting conditions for synthetic image generation. The fidelity of the simulation environment is investigated by comparing the accuracy of computer vision models trained using synthetic image data and trained from real image data collected in a lunar analog environment.
The Tall Lunar Tower project at the NASA Langley Research Center is focused on the design, modeling, fabrication, and testing of a supervised autonomously assembled engineering development unit for tall lunar towers. The lunar south pole environment poses many challenges for robotic assembly of the tall tower, particularly to computer vision camera systems due to a high-contrast lighting environment. This paper will present an Unreal Engine 5 video game engine Lunar South Pole Lighting Testbed to simulate realistic lunar lighting conditions for synthetic image generation. The fidelity of the simulation environment is investigated by comparing the accuracy of computer vision models trained using synthetic image data and trained from real image data collected in a lunar analog environment.
The Tall Lunar Tower project at the NASA Langley Research Center is focused on the design, modeling, fabrication, and testing of a supervised autonomously assembly engineering development unit for tall lunar towers. The lunar south pole environment poses many challenges for robotic assembly of the tall tower, particularly to computer vision camera systems due to a high-contrast lighting environment. This paper will present an Unreal Engine 5 video game engine Lunar South Pole Lighting Testbed to simulate realistic lunar lighting conditions for synthetic image generation. The fidelity of the simulation environment is investigated by comparing the accuracy of computer vision models trained using synthetic image data and trained from real image data collected in a lunar analog environment.
Several proposed space missions include precision reflectors that are larger in diameter than any current or proposed launch vehicle. Most of these reflectors will require a truss structure to accurately position the reflector panels and these reflectors will likely require assembly in orbit. A research program has been conducted at the NASA Langley Research Center to develop the technology required for the robotic assembly of truss structures. The focus of this research has been on hardware concepts, computer software control systems, and operator interfaces necessary to perform supervised autonomous assembly. A special facility was developed and four assembly and disassembly tests of a 102-strut tetrahedral truss have been conducted. The test procedures were developed around traditional 'pick-and-place' robotic techniques that rely on positioning repeatability for successful operation. The data from two of the four tests were evaluated and are presented in this report. All operations in the tests were controlled by predefined sequences stored in a command file, and the operator intervened only when the system paused because of the failure of an actuator command. The tests were successful in identifying potential pitfalls in a telerobotic system, many of which would not have been readily anticipated or incurred through simulation studies. Addressing the total integrated task, instead of bench testing the component parts, forced all aspects of the task to be evaluated. Although the test results indicate that additional developments should be pursued, no problems were encountered that would preclude automated assembly in space as a viable construction method.
Consideration is given to a possible robotic system for the construction of large space structures, which may be described as a multiple general purpose arm manipulator vehicle that can walk over the structure under construction to a given site for further work. A description is presented of the locomotion of such a vehicle, modeling its arms in terms of a currently available industrial manipulator. It is noted that for whatever maximum speed of operation is chosen, rapid changes in robot velocity create situations in which already-selected handholds are no longer practical. A step is added to the 'free gait' walking algorithm in order to solve this problem.
The topics are presented in viewgraph form and include: automated structural assembly robot vision; machine vision requirements; vision targets and hardware; reflective efficiency; target identification; pose estimation algorithms; triangle constraints; truss node with joint receptacle targets; end-effector mounted camera and light assembly; vision system results from optical bench tests; and future work.
This paper summarizes the background of the Pathfinder Project, In-Space Assembly, and Construction activity for fiscal year 1989. Work is presented on high strength mechanical truss joints and the definition of typical large components that might be required for assembly on-orbit and use on interplanetary space missions. Several mechanical joints were designed, and the most promising early design is presented in detail. The primary design drivers were the ability for robot assembly, the correction of up to a + or - 0.020 inch axial misalignment, and an axial load in the vicinity of + or - 100,000 lb. The most promising joint uses axisymmetric grooves to correct the misalignment and to transfer the load in a smooth path.
When assembling Superconducting Radio Frequency (SRF) Cavities, maintaining an environment devoid of particulates like dust and other small particles is essential. If a single spec of dust enters the cavity a significant degradation of performance can occur. To avoid a cavity failure Fermilab assembles the SRF cavities within a ISO-4 (Class 10) environment. This environment though is still susceptible to foreign contaminants when technicians enter and new components are added to the cleanroom. To reduce the risk even more Fermilab has introduced a cobot manipulator into the cleanroom environment to speed up the assembly time which will reduce the time that the technicians operate in the cleanroom. But, this still leaves the potential of contaminants to enter the cleanroom if new components need to be tested within the cleanroom. This project aims to lay the groundwork to develop a Digital Twin environment of the cleanroom to aid in manufacturing processes and testing. In its simplest form, a digital twin is a bidirectional link between a physical system and its digital counterpart or twin. NVIDIA Isaac Sim is used as the digital twin foundation for the digital representation of the cleanroom, specifically for the UR16e assembly area. A simulated UR16e was used to validate the performance of Isaac Sim as a testing environment by comparing the tool center points (TCP) positional data between the simulated and digital representation of the UR16e. Due to a new vision based robotic assembly process being introduced to the cleanroom a digital representation of the physical camera was tested and validated to ensure that it will produce close to the same outcome as the physical environment. The TCP comparison results showed a peak translational error of approximately 0.1mm and rotational errors of up to 8 between the simulated and digital UR16es. While the camera validation performed with high repeatability across multiple runs, it still requires minor tuning before it can accurately replicate a physical camera.
Presented are the research results from the research grant entitled: Active Control of Robot Manipulators, sponsored by the Goddard Space Flight Center (NASA) under grant number NAG-780. This report considers a class of robot manipulators based on the closed-kinematic chain mechanism (CKCM). This type of robot manipulators mainly consists of two platforms, one is stationary and the other moving, and they are coupled together through a number of in-parallel actuators. Using spatial geometry and homogeneous transformation, a closed-form solution is derived for the inverse kinematic problem of the six-degree-of-freedom manipulator, built to study robotic assembly in space. Iterative Newton Raphson method is employed to solve the forward kinematic problem. Finally, the equations of motion of the above manipulators are obtained by employing the Lagrangian method. Study of the manipulator dynamics is performed using computer simulation whose results show that the robot actuating forces are strongly dependent on the mass and centroid locations of the robot links.