Vision-Guided Robot for Planetary Habitat Assembly

The NASA Engineering and Safety Center (NESC) was established in 2003 (after the Columbia accident) to provide an independent technical resource for the resolution of challenging technical problems (through the use of studies, analysis, tests, etc.) for NASA programs and projects. Since its inception, NESC has completed nearly 1000 technical assessments for NASA’s Human Exploration and Operation Mission Directorate (HEOMD), Science Mission Directorate (SMD), Space Technology Mission Directorate (STMD), and Aeronautics Research Mission Directorate (ARMD). Of the SMD related assessments, several were for the resolution of technical problems, analysis, or studies related to NASA’s astrophysics missions in various phases of the project from design to operation. Some of the recent examples of NESC technical support for NASA astrophysics missions have been for: Hubble Space Telescope (HST), Chandra X-ray Observatory (CXO), Fermi Gamma-ray Space Telescope, Kepler Space Telescope, Transiting Exoplanet Survey Satellite (TESS), James Webb Space Telescope (JWST), and Laser Interferometer Space Antenna (LISA). In this paper, we outline some of the technical challenges faced by these astrophysics missions and describe how NESC contributed to their resolution. The case studies cover a wide range of disciplines involving space telescopes, detectors, lasers, and attitude control systems. These efforts include innovative solutions for extending the life of the missions, technical resolution of challenging problems, strategies for risk mitigation, and failure investigations combined with lessons learned reports to advance discipline knowledge, enhance NASA capabilities, and avoid future problems.

Dynamics and control for in-space assembly robots with large translational and rotational maneuvers

The National Aeronautics and Space Administration (NASA) Centennial Challenges Program, part of the Space Technology Mission Directorate (STMD), addresses key technology needs of NASA and the nation, while facilitating new sources of innovation outside the traditional community. This is done by the direct engagement of the public at large, through the offering of Congressional authorized prize purses and associated challenges developed by NASA and the aerospace community and set up as a competition awarding the prize money for achieving the specified technology goal.

NASA’s newly minted Space Technology Mission Directorate (STMD) is supporting the fabrication of a sail of this design in preparation of a planned 2014 flight. This mission, dubbed Sunjammer, will further advance the potential of propellantless solar sails. The Sunjammer mission is being led by the private company L’Garde Inc. of Tustin, CA. Sunjammer is named after a short story written by Sir Arthur C. Clarke. This ambitious project aims to prove the efficacy of a versatile and scalable solar sail design.

Personnel from NASA's MSFC have been investigating the feasibility of an advanced propulsion system known as the Electric Sail (E-Sail) for future scientific exploration missions. This team initially won a NASA Space Technology Mission Directorate (STMD) Phase I NASA Innovative Advanced Concept (NIAC) award and then a two-year follow-on Phase II NIAC award in October 2015. This paper documents the findings from this three-year investigation. An Electric sail, a propellant-less propulsion system, uses solar wind ions to rapidly travel either to deep space or the inner solar system. Scientific spacecraft could reach Pluto in ~5 years, or the boundary of the solar system in ten to twelve years compared to the thirty-five plus years the Voyager spacecraft took. The team's recent focuses have been: 1) Developing a Particle in Cell (PIC) numeric engineering model from MSFC's experimental data on the interaction between simulated solar wind and a charged bare wire that can be applied to a variety of missions, 2) Determining what missions could benefit from this revolutionary propulsion system, 3) Conceptualizing spacecraft designs for various tasks: to reach the solar system's edge, to orbit the sun as Heliophysics sentinels, or to examine a multitude of asteroids.

Additive manufacturing (AM) has gained notoriety for offering advantages over traditional manufacturing methods, such as increased design complexity and flexibility. However, it has not found widespread use beyond rapid prototyping. One hindrance to the acceptance of AM processes in industry is the time and cost of fabrication per component. While metal AM by itself can be inexpensive, extra manufacturing steps in the form of subtractive manufacturing (SM) may need to be performed to reach final part tolerances, leading to hybrid additive-subtractive manufacturing (HASM) of a part, which increases time and cost. A potential area to reduce cost is through increasing the efficiency of the HASM process by conducting additive and subtractive manufacturing simultaneously. Usually, HASM is performed in a process where AM is completed in one machine or cell and transferred to another machine or cell for SM in a sequential assembly line process. This efficiency decreases part cost, but high aspect ratio parts or parts with internal geometry that require interleaved additive deposition and machining cannot be produced. One unexplored solution to simultaneous HASM that allows for interleaved operations is to operate the deposition head and machining spindle concurrently within the same machine envelope, known as concurrent HASM (CHASM). In this type of process, both AM and SM occur simultaneously on a batch of small parts or a single large part, maintaining a high efficiency without sacrificing the full range of complex geometries that AM allows for. A potential approach to the single-machine method could be to combine a robot and mill within the same envelope. A challenge to this approach, however, is control of both systems. Most machine controllers have limited external communication or, if a robot has been integrated, only offer movement of either the robot or mill at any given time. As a result, systems must pause either the AM or SM process to switch between them rather than working simultaneously. The present work investigates the positional accuracy of such a CHASM system comprised of a robotic arm and a 3-axis mill. Open-loop tests with limited communication between machines are performed on the system to verify positional error during concurrent robot-mill movements. Under certain conditions, it is demonstrated that position error can stay within 2 mm for the duration of a single layer; however, these tests show that, generally, the open-loop positioning performance of the system is inadequate for CHASM without part-specific hand-tuning of parameters. Based on these results, a set of requirements for successful robot-CNC CHASM is proposed for future integrations.

The development and design of a functionally-graded material (FGM) robotic arm for supporting and manipulating a <br> vision system is discussed in this paper. The aim is to understand if using FGMs effectively reduce mass compared to <br> single material parts. The evolution of ideas using topological optimisation (TO) and FGMs towards the design are <br> shown and reviewed. The final design uses TO, and as such needs to be manufactured using additive manufacture <br> (AM). Constraints have been put in place to ensure physical manufacturability is possible. The final design reduces <br> the mass compared to the original arm by 61.4%.

A computer vision and robotic system for an intelligent workstation

Robotic assembly of architectural structures has been an area of research for a few decades. Yet, current methods impose a large number of constraints on the geometry of those structures. In this paper we introduce a method for robotic assembly that enables the construction of double curved self-supporting structures. Latest research challenges have focused on the assembly of sophisticated brick structures and on sensor feedback systems for handling accuracy. We propose an alternative strategy to tackle tolerance handling in complex structures that rely on geometry. The intelligence of the system lies in two main aspects: a subdivision technique that incorporates the robot’s constraints as well as the structural equilibrium of the structure during each step of assembly, in order to omit the use of scaffolding; and a match between geometric information and the robot’s movements in a robot programming environment. As a proof of concept, we fabricated a portion of a full-scale double-curved structure. The structure was assembled without scaffolding by a portable KUKA KR10 on a randomly picked site. This project aims to demonstrate an easy and simple method for robotic assembly that enables the realization of digitally generated complex geometries as concrete complex structures.

Present trend in automating the batch production industries which manufactures a family of parts uses the flexible part feeder with the vision system to feed the part into the system. The vision system makes the system complex and costly which limits the use of flexible part feeders. To increase the use of the flexible part feeder low-cost flexible part feeders have to be used. To reduce the cost, replacement of the vision system and the robotic arm has to be done. Thus designing a flexible part feeder with an alternative to the vision system and robotic arm for a family of parts could serve as an initiative to reduce the cost of the currently used flexible part feeder. This article focuses on the development of a flexible part feeder without vision system and robotic arm. The approach involves finding the replacement of the vision system, designing the flexible part feeder for a family of parts in three steps, development of identification unit with the help of the replacement found and integrating the identification unit with the controller and controlling the orienting tools with the help of pneumatic actuator followed by testing of the setup for the functional requirement. The work throws light on the replacement of vision system with the capacitive proximity sensors and to replace the robotic arm with the help of orienting tools and thereby reducing the cost and complexity.

The robotic arm is one of the vital components of robot assembly. The purpose of the robotic arm is to transmit power and conduct the desired motion, i.e., translation or rotation. Robotic limbs are designed and constructed to execute certain tasks with a high degree of speed, accuracy, and efficiency. This research focuses on to enhancing the strength-to-weight ratio of robotic arm using certain techniques of additive manufacturing, i.e., topology optimization and lattice structure. Employing the finite element analysis, the impact of weight reduction optimization on structural parameters such as stress and deformation in the current design is assessed using ANSYS R18.1 for FE analysis and Creo parametric 7.0 design software for computer-aided design modeling. Observations reveal that the 0.5 and .4 scale lattice structure designs have deformation of 0.01453mm and 0.01453 mm respectively though the generic design has 0.01043 mm deformation. Notably, the 0.5 scale lattice of the robotic arm exhibits a 31.08% higher equivalent stress than the generic design with 29.3%. reduction in mass of the robotic arm. These findings highlight the efficacy of lattice structures for optimizing the robotic arm’s performance, contributing to advancements in power-efficient robot assembly processes.

This research investigates the robotic assembly of timber structures connected by wood–wood connections. As the digitization of the timber construction sector progresses, digital tools, such as industrial robotic arms and Computer Numerical Control machines, are becoming increasingly accessible. The new-found ease with which wood can be processed stimulates a renewed interest in traditional joinery, where pieces are simply interlocked instead of being connected by additional metallic parts. Previous research established a computational workflow for the robotic assembly of timber plate structures connected by wood–wood connections. This paper focuses on determining the physical conditions that allow inserting through-tenon joints with a robot. The main challenge lies in minimizing the clearance between the tenon and the mortise in order to keep the connections as tight as possible. An experimental protocol has, therefore, been developed to quantitatively assess the performance of the insertion according to different geometric parameters. Robotic insertion tests have been carried out on over 50 samples of 39 mm Laminated Veneer Lumber. Results showed the interest of tapering the joint with a 5 degrees angle, in addition to introducing an offset of 0.05 mm, to minimize friction forces during the insertion. This configuration was confirmed by successfully assembling a 2,50 m long box girder with the same parameters.

This paper describes a new approach for the visual pose estimation of an uncertain robotic manipulator using ANFIS (Artificial Neuro-Fuzzy Inference System) and two uncalibrated cameras. The main emphasis of this work is on the ability to estimate the positioning accuracy and repeatability of a low-cost robotic arm with unknown parameters under uncalibrated vision system. The vision system is composed of two cameras; installed on the top and on the lateral side of the robot, respectively. These two cameras need no calibration; thus, they can be installed in any position and orientation with just the condition that the end-effector of the robot must remain always visible. A red-colored feature point is fixed on the end of the third robotic arm link. In this study, captured image data via two fixed-cameras vision system are used as the sensor feedback for the position tracking of an uncertain robotic arm. LabVolt R5150 manipulator in our laboratory is used as case study. The visual estimation system is trained using ANFIS with subtractive clustering method in MATLAB. In MATLAB, the robot, feature point and cameras are simulated as physical behaviors. To get the required data for ANFIS, the manipulator was maneuvered within its workspace using forward kinematics and the feature point image coordinates were acquired with the two cameras. Simulation experiments show that the location of the robotic arm can be trained in ANFIS using two uncalibrated cameras; and problems for computational complexity and calibration requirement of multi-view geometry can be eliminated. Observing Mean Square Error (MSE), Root Mean Square Error (RMSE), Error Mean and Standard Deviation Errors, the performance of the proposed approach is efficient for using as visual feedback in uncertain robotic manipulator. Further, the proposed approach using ANFIS and uncalibrated vision system has better in flexibility, user-friendly manner and computational concepts over conventional techniques.

In multilevel or additive production, reduction of the total manufacturing duration is crucial. This may be achieved by harmonizing assembly and production time and by simultaneous collaboration with component manufacturers, thus incurring fewer delays. Here, a novel approach, the African buffalo-inspired part segregation algorithm, is proposed for optimal structural and functional assemblies in additive manufacturing. A mixed-integer nonlinear programming model is developed to assess the near-term optimum criteria area and dispersed materials in a computational manufacturing context. The number of support substances, total production period and total assembly costs are reduced in the time-reduction approach. A specific swarm intelligence-part-based segregation strategy is used to choose the appropriate number of element assemblages, and a part division strategy that complies with the criteria for transverse effect, dimensions and elevations is applied. The proposed approach is evaluated for structures with conventional and free-form borders using two real-size three-dimensional representations. The results indicate that this method may reduce overall production time compared to the time spent constructing one component, under all investigated circumstances.

Future robotic assembly systems will allow product designers to upload their assembled product models remotely such that they can be assembled autonomously. In this work we present the architecture for a Click and Assemble Robotic Assembly (CARA) system. This architecture takes an assembly file uploaded by the user through a web interface as the only input. It then performs all the necessary planning before executing the assembly. To the authors’ knowledge, this is the first time that all of the required components from previous advances in robotic assembly have been brought together, with all interconnecting challenges solved, into a complete working system for physical, real world assembly tasks. To demonstrate the implemented architecture capabilities, a real industrial product with tight tolerances was assembled from its CAD file only, illustrating the end to end robotic assembly premise in a real world setting.