[ { "id": "authors:bz7xr-pp971", "collection": "authors", "collection_id": "bz7xr-pp971", "cite_using_url": "https://authors.library.caltech.edu/records/bz7xr-pp971", "type": "conference_item", "title": "CaRT: Certified Safety and Robust Tracking in Learning-Based Motion Planning for Multi-Agent Systems", "book_title": "2023 62nd IEEE Conference on Decision and Control (CDC)", "author": [ { "family_name": "Tsukamoto", "given_name": "Hiroyasu", "orcid": "0000-0002-6337-2667", "clpid": "Tsukamoto-Hiroyasu" }, { "family_name": "Rivi\u00e8re", "given_name": "Benjamin", "orcid": "0000-0003-4189-4090", "clpid": "Rivi\u00e8re-Benjamin" }, { "family_name": "Choi", "given_name": "Changrak", "orcid": "0000-0001-8869-6839", "clpid": "Choi-Changrak" }, { "family_name": "Rahmani", "given_name": "Amir", "clpid": "Rahmani-Amir" }, { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" } ], "abstract": "
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The key innovation of our analytical method, CaRT, lies in establishing a new hierarchical, distributed architecture to guarantee the safety and robustness of a given learning-based motion planning policy. First, in a nominal setting, the analytical form of our CaRT safety filter formally ensures safe maneuvers of nonlinear multi-agent systems, optimally with minimal deviation from the learning-based policy. Second, in off-nominal settings, the analytical form of our CaRT robust filter optimally tracks the certified safe trajectory, generated by the previous layer in the hierarchy, the CaRT safety filter. We show using contraction theory that CaRT guarantees safety and the exponential boundedness of the trajectory tracking error, even under the presence of deterministic and stochastic disturbance. Also, the hierarchical nature of CaRT enables enhancing its robustness for safety just by its superior tracking to the certified safe trajectory, thereby making it suitable for off-nominal scenarios with large disturbances. This is a major distinction from conventional safety function-driven approaches, where the robustness originates from the stability of a safe set, which could pull the system over-conservatively to the interior of the safe set. Our log-barrier formulation in CaRT allows for its distributed implementation in multi-agent settings. We demonstrate the effectiveness of CaRT in several examples of nonlinear motion planning and control problems, including optimal, multi-spacecraft reconfiguration.
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", "doi": "10.1109/cdc49753.2023.10383600", "isbn": "979-8-3503-0124-3", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "2023-12", "pages": "2910-2917" }, { "id": "authors:1d9qf-h5522", "collection": "authors", "collection_id": "1d9qf-h5522", "cite_using_url": "https://authors.library.caltech.edu/records/1d9qf-h5522", "type": "conference_item", "title": "Online Self-Supervised Thermal Water Segmentation for Aerial Vehicles", "book_title": "2023 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)", "author": [ { "family_name": "Lee", "given_name": "Connor", "orcid": "0000-0002-5008-4092", "clpid": "Lee-Connor" }, { "family_name": "Gustafsson Frennert", "given_name": "Jonathan", "clpid": "Gustafsson-Frennert-Jonathan" }, { "family_name": "Gan", "given_name": "Lu", "orcid": "0000-0003-0911-8032", "clpid": "Gan-Lu" }, { "family_name": "Anderson", "given_name": "Matthew", "clpid": "Anderson-Matthew" }, { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" } ], "abstract": "
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We present a new method to adapt an RGB-trained water segmentation network to target-domain aerial thermal imagery using online self-supervision by leveraging texture and motion cues as supervisory signals. This new thermal capability enables current autonomous aerial robots operating in near-shore environments to perform tasks such as visual navigation, bathymetry, and flow tracking at night. Our method overcomes the problem of scarce and difficult-to-obtain near-shore thermal data that prevents the application of conventional supervised and unsupervised methods. In this work, we curate the first aerial thermal near-shore dataset, show that our approach outperforms fully-supervised segmentation models trained on limited target-domain thermal data, and demonstrate real-time capabilities onboard an Nvidia Jetson embedded computing platform. Code and datasets used in this work will be available at: https://github.com/connorlee77/uav-thermal-water-segmentation.
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", "doi": "10.1109/iros55552.2023.10342016", "isbn": "978-1-6654-9190-7", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "2023-10" }, { "id": "authors:8c9ap-wjc47", "collection": "authors", "collection_id": "8c9ap-wjc47", "cite_using_url": "https://authors.library.caltech.edu/records/8c9ap-wjc47", "type": "conference_item", "title": "SPAMMM - Solar Powered Array for Melting Materials on the Moon", "book_title": "2023 Regional Student Conferences", "author": [ { "family_name": "Singh", "given_name": "Parul R.", "clpid": "Singh-Parul-R" }, { "family_name": "Ng", "given_name": "Nathan", "clpid": "Ng-Nathan" }, { "family_name": "Patel", "given_name": "Avi", "clpid": "Patel-Avi" }, { "family_name": "Garrido", "given_name": "Camilo", "clpid": "Garrido-Camilo" }, { "family_name": "Carey", "given_name": "Hazel", "clpid": "Carey-Hazel" }, { "family_name": "Daghlian", "given_name": "Saren", "clpid": "Daghlian-Saren" }, { "family_name": "Ray", "given_name": "Rasool I.", "clpid": "Ray-Rasool-I" }, { "family_name": "Pulungan", "given_name": "Kemal", "clpid": "Pulungan-Kemal" }, { "family_name": "Polidoro", "given_name": "Sophie", "clpid": "Polidoro-Sophie" }, { "family_name": "Zheng", "given_name": "Catherine", "clpid": "Zheng-Catherine" }, { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" } ], "abstract": "
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To establish a long-term human presence on the Moon, NASA will rely on the in-situ resource utilization, or ISRU, of native ores in its lunar metal production pipeline. Therefore, developing a practical, sustainable, and affordable method to extract useful metals from these native ores is essential for all future lunar manufacturing and construction efforts. This paper presents the Solar Powered Apparatus for Melting Materials on the Moon, or SPAMMM, as a metal extraction solution to be implemented on the Moon’s South Pole, one of the targeted Artemis landing sites. SPAMMM consists of a central “power tower” that contains gas injection valves, a depressurization valve, a distillation chamber, a precipitate chamber, and a furnace that separates metals from their initial ores via concentrated solar radiation from a foldable parabolic mirror. In order to leverage the uniquely shallow angle of incident light at the South Pole, this parabolic mirror is rotated about the furnace to track the weeks-long daylight. To maximize efficiency, the radius of the mirror’s path has been designed to be the mirror’s focal length. The paper is divided into the following sections: (1) Problem Statement, where the need for ISRU in the lunar metal production pipeline is explained; (2) Project Description, where the requirements, concept of operations, and design overview are detailed; (3) Ore Extraction, which discusses the power tower design and chemical processes behind extracting metal from specific lunar ores; (4) Rotating Parabolic Concentrator, which details the design, optical specifications, and thermal capabilities of the rotating parabolic mirror; (5) Verification Testing Program, which outlines the system and subsystem testing plan that will bring SPAMMM to a Technology Readiness Level of 5 and details any additional consideration for SPAMMM’s lunar implementation. If awarded funding through the 2023 NASA BIG Idea Challenge, future work will involve developing, designing, and validating every subsystem of SPAMMM in the relevant environment.

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", "doi": "10.2514/6.2023-71914", "isbn": "978-1-62410-719-1", "publisher": "AIAA", "place_of_publication": "Reston, VA", "publication_date": "2023-01" }, { "id": "authors:f9r48-68t37", "collection": "authors", "collection_id": "f9r48-68t37", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191007-132043345", "type": "conference_item", "title": "DGNSS-Vision Integration for Robust and Accurate Relative\n Spacecraft Navigation", "author": [ { "family_name": "Capuano", "given_name": "V.", "orcid": "0000-0002-6886-5719", "clpid": "Capuano-V" }, { "family_name": "Harvard", "given_name": "A.", "clpid": "Harvard-A" }, { "family_name": "Lin", "given_name": "Y.", "clpid": "Lin-Yvette" }, { "family_name": "Chung", "given_name": "S. J.", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" } ], "abstract": "Relative spacecraft navigation based on Global Navigation Satellite System (GNSS) has been already successfully performed in low earth orbit (LEO). Very high accuracy, of the order of the millimeter, has been achieved in postprocessing using carrier phase differential GNSS (CDGNSS) and recovering the integer number of wavelength (Ambiguity)\nbetween the GNSS transmitters and the receiver. However the performance achievable on-board, in real time,\nabove LEO and the GNSS constellation would be significantly lower due to limited computational resources, weaker\nsignals, and worse geometric dilution of precision (GDOP). At the same time, monocular vision provides lower accuracy\nthan CDGNSS when there is significant spacecraft separation, and it becomes even lower for larger baselines and wider field of views (FOVs). In order to increase the robustness, continuity, and accuracy of a real-time on-board\nGNSS-based relative navigation solution in a GNSS degraded environment such as Geosynchronous and High Earth\nOrbits, we propose a novel navigation architecture based on a tight fusion of carrier phase GNSS observations and\nmonocular vision-based measurements, which enables fast autonomous relative pose estimation of cooperative spacecraft\nalso in case of high GDOP and low GNSS visibility, where the GNSS signals are degraded, weak, or cannot be\ntracked continuously.\nIn this paper we describe the architecture and implementation of a multi-sensor navigation solution and validate the\nproposed method in simulation. We use a dataset of images synthetically generated according to a chaser/target relative\nmotion in Geostationary Earth Orbit (GEO) and realistic carrier phase and code-based GNSS observations simulated\nat the receiver position in the same orbits. We demonstrate that our fusion solution provides higher accuracy, higher\nrobustness, and faster ambiguity resolution in case of degraded GNSS signal conditions, even when using high FOV\ncameras.", "publisher": "Caltech Library", "publication_date": "2019-09" }, { "id": "authors:nn5qr-hqx07", "collection": "authors", "collection_id": "nn5qr-hqx07", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190722-095828499", "type": "conference_item", "title": "Distributed multi-target relative pose estimation for cooperative spacecraft swarm", "author": [ { "family_name": "Matsuka", "given_name": "Kai", "orcid": "0000-0003-2116-9756", "clpid": "Matsuka-Kai" }, { "family_name": "Lupu", "given_name": "Elena Sorina", "orcid": "0000-0002-3968-2630", "clpid": "Lupu-E-S" }, { "family_name": "Nakka", "given_name": "Yashwanth Kumar", "orcid": "0000-0001-7897-3644", "clpid": "Nakka-Yashwanth-K" }, { "family_name": "Foust", "given_name": "Rebecca", "orcid": "0000-0003-1470-1716", "clpid": "Foust-Rebecca" }, { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" }, { "family_name": "Had\u00e6gh", "given_name": "Fred", "clpid": "Hadaegh-F-Y" } ], "abstract": "Multi-agent relative state estimation is critical in enabling full swarm autonomy. However, relative pose estimation of hundreds to thousands of cooperative agents is challenging due to limited sensing, limited communication, and scalability. We present a distributed algorithm for cooperative multi-agent localization with both limited relative sensing and communication. Each agent locally exchanges the relative measurements and jointly estimates the relative poses of its local neighbors. Because the algorithm only estimates the local neighbors, the number of states does not grow with the total number of agents given the same local sensing and communication graphs, making the algorithm suitable for swarm application. The proposed algorithm is applied to spacecraft swarm localization and verified in simulation and experiments. Experiments are conducted on Caltech's robotic spacecraft simulators, the Multi-Spacecraft Testbed for Autonomy Research (M-STAR), where each spacecraft uses vision-based relative measurements.", "publisher": "Caltech Library", "publication_date": "2019-07-22" }, { "id": "authors:63tkr-nrs81", "collection": "authors", "collection_id": "63tkr-nrs81", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190109-131619062", "type": "conference_item", "title": "Controllability and Design of Unmanned Multirotor Aircraft Robust to Rotor Failure", "book_title": "AIAA Scitech 2019 Forum", "author": [ { "family_name": "Kim", "given_name": "Kyunam", "orcid": "0000-0002-7803-1582", "clpid": "Kim-Kyunam" }, { "family_name": "Rahili", "given_name": "Salar", "clpid": "Rahili-S" }, { "family_name": "Shi", "given_name": "Xichen", "clpid": "Shi-Xichen" }, { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" }, { "family_name": "Gharib", "given_name": "Morteza", "orcid": "0000-0003-0754-4193", "clpid": "Gharib-M" } ], "abstract": "A new design method for multi-rotor aircraft with distributed electric propulsion is presented\nto ensure a property of robustness against rotor failure from the control perspective. Based on the concept of null controllability, a quality measure is derived to evaluate and quantify the performance of a given design with the consideration of rotor failure. An optimization\nproblem whose cost function is based on the quality measure is formulated and its optimal solution identifies a set of optimal design parameters that maximizes an aircraft's ability to control its attitude and hence its position. The effectiveness of the proposed design procedure\nis validated through the results of experimentation with the Autonomous Flying Ambulance model being developed at Caltech's Center for Autonomous Systems and Technologies.", "doi": "10.2514/6.2019-1787", "isbn": "978-1-62410-578-4", "publication_date": "2019-01", "pages": "1-13" }, { "id": "authors:11yzk-3pj65", "collection": "authors", "collection_id": "11yzk-3pj65", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190109-132309708", "type": "conference_item", "title": "Robust Features Extraction for On-board Monocular-based Spacecraft Pose Acquisition", "book_title": "AIAA Scitech 2019 Forum", "author": [ { "family_name": "Capuano", "given_name": "Vincenzo", "orcid": "0000-0002-6886-5719", "clpid": "Capuano-V" }, { "family_name": "Alimo", "given_name": "Shahrouz Ryan", "clpid": "Alimo-S-R" }, { "family_name": "Ho", "given_name": "Andrew Q.", "clpid": "Ho-Andrew-Q" }, { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" } ], "abstract": "This paper presents the design, implementation, and validation of a robust feature extraction architecture for real-time on-board monocular vision-based pose initialization of a target spacecraft in application to on-orbit servicing and formation flying. The proposed computer vision algorithm is designed to detect the most significant features of an uncooperative target spacecraft in a sequence of two-dimensional input images that are collected on board the chaser spacecraft. A novel approach based on the fusion of multiple and parallel processing streams is proposed to filter a minimum number of extracted true point features, even in case of unfavourable illumination conditions and in presence of Earth in the background. These are then combined into relevant polyline structures that characterize the true geometrical shape of the target spacecraft.", "doi": "10.2514/6.2019-2005", "isbn": "978-1-62410-578-4", "publication_date": "2019-01", "pages": "Art. No.-2019-2005" }, { "id": "authors:rcrtq-ztb53", "collection": "authors", "collection_id": "rcrtq-ztb53", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190109-132944040", "type": "conference_item", "title": "Solving Optimal Control with Nonlinear Dynamics Using Sequential Convex Programming", "book_title": "AIAA Scitech 2019 Forum", "author": [ { "family_name": "Foust", "given_name": "Rebecca", "orcid": "0000-0003-1470-1716", "clpid": "Foust-Rebecca" }, { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" }, { "family_name": "Hadaegh", "given_name": "Fred Y.", "clpid": "Hadaegh-F-Y" } ], "abstract": "Sequential convex programming (SCP) is a useful tool in obtaining real-time solutions to direct optimal control, but it is unable to adequately model nonlinear dynamics due to the linearization and discretization required. As nonlinear program solvers are not yet functioning\nin real-time, a tool is needed to bridge the gap between satisfying the nonlinear dynamics and completing execution fast enough to be useful. This paper presents a real-time control algorithm, sequential convex programming with nonlinear dynamics correction (SCPn), which ameliorates the performance of SCP under nonlinear dynamics. Simulations are presented to validate the efficacy of the method.", "doi": "10.2514/6.2019-0652", "isbn": "978-1-62410-578-4", "publication_date": "2019-01", "pages": "1-15" }, { "id": "authors:97hth-tde87", "collection": "authors", "collection_id": "97hth-tde87", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181010-123842437", "type": "conference_item", "title": "Ultra-Soft Electromagnetic Docking with Applications to In-Orbit Assembly", "author": [ { "family_name": "Foust", "given_name": "Rebecca C.", "orcid": "0000-0003-1470-1716", "clpid": "Foust-Rebecca" }, { "family_name": "Lupu", "given_name": "Elena Sorina", "orcid": "0000-0002-3968-2630", "clpid": "Lupu-E-S" }, { "family_name": "Nakka", "given_name": "Yashwanth Kumar", "orcid": "0000-0001-7897-3644", "clpid": "Nakka-Yashwanth-K" }, { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" }, { "family_name": "Hadaegh", "given_name": "Fred Y.", "clpid": "Hadaegh-F-Y" } ], "abstract": "Docking small satellites in space is a high-risk operation due to the uncertainty in relative position and orientation and the lack of mature docking technologies. This is particularly true for missions that involve multiple docking and undocking procedures like swarm-based construction and reconfiguration. In this paper, an electromagnetic docking system is proposed to mitigate these risks through robust, ultra-soft, propellant-free docking. Designed with reconfigurable self-assembly in mind, the gripping mechanism is androgynous, able to dock at a variety of relative orientations, and tolerant of small misalignments. The mechanical and control design of the system is presented and tested in both simulation and on a fleet of 6 degree-of-freedom (DOF) spacecraft simulators. The spacecraft simulators oat on the precision flat floor facility in the Caltech Aerospace Robotics and Control lab, the largest of its kind at any university. The performance of the electromagnetic docking system on-board the simulators is then compared against a propulsive docking system.", "publisher": "International Astronautical Federation", "publication_date": "2018-10" }, { "id": "authors:2v2h8-jda31", "collection": "authors", "collection_id": "2v2h8-jda31", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181010-123200583", "type": "conference_item", "title": "Autonomous Small Body Mapping and Spacecraft Navigation Via Real-Time SPC-SLAM", "author": [ { "family_name": "Baldini", "given_name": "Francesca", "clpid": "Baldini-F" }, { "family_name": "Harvard", "given_name": "Alexei", "clpid": "Harvard-A" }, { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" }, { "family_name": "Nesnas", "given_name": "Issa", "clpid": "Nesnas-I-A-D" }, { "family_name": "Bhaskaran", "given_name": "Shyamkumar", "clpid": "Bhaskaran-S" } ], "abstract": "Current methods for pose and shape estimation of small bodies, such as comets and asteroids, rely on extensive ground support and significant use of radiometric measurements using the Deep Space Network. The Stereo-Photoclinometry (SPC) technique is currently used to provide detailed topological information about a small body as well as its absolute orientation and position. While this technique has produced very accurate estimates, the core algorithm cannot be run in real-time and requires a team of scientists on the ground who must communicate with the spacecraft in order to oversee SPC operations. Autonomous onboard navigation addresses these limitations by eliminating the need for human oversight. In this paper, we present an optimization-based estimation algorithm for navigation that allows the spacecraft to autonomously approach and maneuver around an unknown small body by mapping its geometric shape, estimating its orientation, and simultaneously determining the trajectory of the center of mass of the small body. We show the effectiveness of the proposed algorithm using simulated data from a previous flight mission to Comet 67P.", "publisher": "International Astronautical Federation", "publication_date": "2018-10" }, { "id": "authors:y2mvv-yyq90", "collection": "authors", "collection_id": "y2mvv-yyq90", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181010-125059291", "type": "conference_item", "title": "Monocular-Based Pose Determination of Uncooperative Known and Unknown Space Objects", "author": [ { "family_name": "Capuano", "given_name": "Vincenzo", "orcid": "0000-0002-6886-5719", "clpid": "Capuano-V" }, { "family_name": "Kim", "given_name": "Kyunam", "orcid": "0000-0002-7803-1582", "clpid": "Kim-Kyunam" }, { "family_name": "Hu", "given_name": "Juliette", "clpid": "Hu-Juliette" }, { "family_name": "Harvard", "given_name": "Alexei", "clpid": "Harvard-A" }, { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" } ], "abstract": "In order to support spacecraft proximity operations, such as on-orbit servicing and spacecraft formation flying, several vision-based techniques exist to determine the relative pose of an uncooperative orbiting object with respect to the spacecraft. Depending on whether the object is known or unknown, a shape model of the orbiting target object may have to be constructed autonomously by making use of only optical measurements. In this paper, we investigate two vision-based approaches for pose estimation of uncooperative orbiting targets: one that is general and versatile such that it does not require a priori knowledge of any information of the target, and the other one that requires knowledge of the target's shape geometry. The former uses an estimation algorithm of translational and rotational dynamics to sequentially perform simultaneous pose determination and 3D shape reconstruction of the unknown target, while the latter relies on a known 3D model of the target's geometry to provide a point-by-point pose solution. The architecture and implementation of both methods are presented and their achievable performance is evaluated through numerical simulations. In addition, a computer vision processing strategy for feature detection and matching and the Structure from Motion (SfM) algorithm for on-board 3D reconstruction are also discussed and validated by using a dataset of images that are synthetically generated according to a chaser/target relative motion in Geosynchronous Orbit (GEO).", "publisher": "International Astronautical Federation", "publication_date": "2018-10" }, { "id": "authors:fe3er-haq75", "collection": "authors", "collection_id": "fe3er-haq75", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180706-160821260", "type": "conference_item", "title": "Distributed Control Of An Evolving Satellite Assembly During In-Orbit Construction", "author": [ { "family_name": "Foust", "given_name": "Rebecca C.", "orcid": "0000-0003-1470-1716", "clpid": "Foust-Rebecca" }, { "family_name": "Zhao", "given_name": "Michelle", "clpid": "Zhao-Michelle" }, { "family_name": "Oliver", "given_name": "Suzanne", "clpid": "Oliver-Suzanne" }, { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" }, { "family_name": "Hadaegh", "given_name": "Fred Y.", "clpid": "Hadaegh-F-Y" } ], "abstract": "This paper presents a method for controlling sets of docked satellites during in-orbit construction of a large-scale satellite assembly from a swarm of heterogeneous satellites. Such a system can be used to enable missions from sparse aperture telescopes to elaborate space stations. Once two or more agents from the swarm are docked, the resulting assembly is an over-actuated system so position and attitude controllers must determine which of the available actuators to use. Typically, control allocation for over-actuated systems is done using a simple linear program, but for this scheme the mass properties and number of control points changes. As a result, the linear program solved changes with each new agent that docks with the assembly so the agents must know how to alter the linear program for additional agents and remove control points whose plumes would interact with those agents. In most systems, this linear program is solved by a central computer, but for this system the actuators belong to distinct agents so to increase reliability, each agent solves the same linear program and executes its portion of the resulting control command. This paper sets up the general linear program that each agent in the assembly must solve and then establishes the rules for altering that program when new agents dock. Initial simulations allow the agents to dock as they come into proximity along their respective trajectories to their target locations. This can lead to instability and uncontrollability if the agents dock in certain configurations, so the control allocation rules are extended to prevent uncontrollable or unstable docking scenarios. The logic used for this is based on the moment of inertia and the available actuation ability. Simulations in 6DOF perturbed satellite dynamics show the efficacy of this approach in preventing uncontrollable assemblies and bringing the assemblies together into the desired final configuration.", "publisher": "Caltech Library", "publication_date": "2018-07-06" }, { "id": "authors:3kd0e-b9j39", "collection": "authors", "collection_id": "3kd0e-b9j39", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161206-152153163", "type": "conference_item", "title": "Real-Time Optimal Control and Target Assignment for Autonomous In-Orbit Satellite Assembly from a Modular Heterogeneous Swarm", "author": [ { "family_name": "Foust", "given_name": "Rebecca", "orcid": "0000-0003-1470-1716", "clpid": "Foust-Rebecca" }, { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" }, { "family_name": "Hadaegh", "given_name": "Fred Y.", "clpid": "Hadaegh-F-Y" } ], "abstract": "This paper presents a decentralized optimal guidance and control scheme to combine a heterogeneous swarm of component satellites, rods and connectors, into a large satellite structure. By expanding prior work on a decentralized auction algorithm with model predictive control using sequential convex programming (MPC-SCP) to allow for the limited type heterogeneity and docking ability required for in-orbit assembly. The assignment is performed using a distributed auction with a variable number of targets and strict bonding rules to address the heterogeneity. MPC-SCP is used to generate the collision-free trajectories, with modifications to the constraints to allow docking.", "publisher": "American Astronomical Society AAS", "publication_date": "2016-02-18" }, { "id": "authors:p3ve6-c4j28", "collection": "authors", "collection_id": "p3ve6-c4j28", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170214-131856997", "type": "conference_item", "title": "Feedback-Based Inhomogeneous Markov Chain Approach To Probabilistic Swarm Guidance", "author": [ { "family_name": "Bandyopadhyay", "given_name": "Saptarshi", "clpid": "Bandyopadhyay-S" }, { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" }, { "family_name": "Hadaegh", "given_name": "Fred Y.", "clpid": "Hadaegh-F-Y" } ], "abstract": "This paper presents a novel and generic distributed swarm guidance algorithm using inhomogeneous\nMarkov chains that guarantees superior performance over existing homogeneous\nMarkov chain based algorithms, when the feedback of the current swarm distribution is available.\nThe probabilistic swarm guidance using inhomogeneous Markov chain (PSG\u2013IMC)\nalgorithm guarantees sharper and faster convergence to the desired formation or unknown\ntarget distribution, minimizes the number of transitions for achieving and maintaining the\nformation even if the swarm is damaged or agents are added/removed from the swarm, and\nensures that the agents settle down after the swarm's objective is achieved. This PSG\u2013IMC\nalgorithm relies on a novel technique for constructing Markov matrices for a given stationary\ndistribution. This technique incorporates the feedback of the current swarm distribution,\nminimizes the coefficient of ergodicity and the resulting Markov matrix satisfies motion constraints.\nThis approach is validated using Monte Carlo simulations of the PSG\u2013IMC algorithm\nfor pattern formation and goal searching applications", "publisher": "Caltech Library", "publication_date": "2015-06-08" }, { "id": "authors:ydqek-6sr82", "collection": "authors", "collection_id": "ydqek-6sr82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170214-120751873", "type": "conference_item", "title": "Swarms of Femtosats for Synthetic Aperture Applications", "author": [ { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" }, { "family_name": "Hadaegh", "given_name": "F. Y.", "clpid": "Hadaegh-F-Y" } ], "abstract": "The Silicon Wafer Integrated Femtosatellites (SWIFT) Swarm Project presents a new paradigm-shifting definition of spacecraft technology that can enable flight of swarms of fully capable femtosats. One of the most important applications of SWIFT is a distributed aperture array. \nNew swarm Golay array configurations are introduced and shown to dramatically increase the effective diameter derived from optical performance metrics. A system cost analysis based on this comparison justifies deploying a large number of spacecraft for sparse aperture applications.", "publisher": "Caltech Library", "publication_date": "2011-05-18" } ]