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Prof. Dr. M. Reza Emami
Institute for Aerospace Studies, University of Toronto, Toronto, Canada

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Research Keywords & Expertise

0 Concurrent Engineering
0 Mechatronics
0 Planetary rovers
0 spacecraft formation flying
0 Space systems engineering

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Space manipulators
Mechatronics
Concurrent Engineering
Asteroid engineering

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Journal article
Published: 16 April 2021 in Acta Astronautica
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This paper presents a new image-based control scheme for spacecraft rendezvous and synchronization with an uncooperative tumbling target, which is capable of autonomously adjusting the camera focal length, in order to extend the working range of visual servoing and guarantee that the target remains within the camera field-of-view. Unlike conventional visual servoing, the new scheme is based on a system model that is invariant to changes in camera-intrinsic parameters. An active zooming strategy is proposed which ensures that the target remains in the image plane with a proper size during the visual servoing. By utilizing the image features as feedback information, a finite-time controller is designed, which is robust to the unknown target’s motion as well as the external perturbations, with the ability to estimate and adapt to the upper bound of the uncertainties. The closed-loop system stability is proved using the Lyapunov theory. Simulation scenarios are studied for two different onboard cameras, namely, a fixed-focal-length camera and a zooming camera. In addition, a comparative study with a conventional sliding-mode controller is performed to evaluate the convergence and accuracy of the proposed control scheme.

ACS Style

Xiangtian Zhao; M. Reza Emami; Shijie Zhang. Robust image-based control for spacecraft uncooperative rendezvous and synchronization using a zooming camera. Acta Astronautica 2021, 184, 128 -141.

AMA Style

Xiangtian Zhao, M. Reza Emami, Shijie Zhang. Robust image-based control for spacecraft uncooperative rendezvous and synchronization using a zooming camera. Acta Astronautica. 2021; 184 ():128-141.

Chicago/Turabian Style

Xiangtian Zhao; M. Reza Emami; Shijie Zhang. 2021. "Robust image-based control for spacecraft uncooperative rendezvous and synchronization using a zooming camera." Acta Astronautica 184, no. : 128-141.

Journal article
Published: 13 January 2021 in Advances in Space Research
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This paper presents the mission design for a CubeSat-based active debris removal approach intended for transferring sizable debris objects from low-Earth orbit to a deorbit altitude of 100 km. The mission consists of a mothership spacecraft that carries and deploys several debris-removing nanosatellites, called Deorbiter CubeSats. Each Deorbiter is designed based on the utilization of an eight-unit CubeSat form factor and commercially-available components with significant flight heritage. The mothership spacecraft delivers Deorbiter CubeSats to the vicinity of a predetermined target debris, through performing a long-range rendezvous maneuver. Through a formation flying maneuver, the mothership then performs in-situ measurements of debris shape and orbital state. Upon release from the mothership, each Deorbiter CubeSat proceeds to performing a rendezvous and attachment maneuver with a debris object. Once attached to the debris, the CubeSat performs a detumbling maneuver, by which the residual angular momentum of the CubeSat-debris system is dumped using Deorbiter’s onboard reaction wheels. After stabilizing the attitude motion of the combined Deorbiter-debris system, the CubeSat proceeds to performing a deorbiting maneuver, i.e., reducing system’s altitude so much so that the bodies disintegrate and burn up due to atmospheric drag, typically at around 100 km above the Earth surface. The attitude and orbital maneuvers that are planned for the mission are described, both for the mothership and Deorbiter CubeSat. The performance of each spacecraft during their operations is investigated, using the actual performance specifications of the onboard components. The viability of the proposed debris removal approach is discussed in light of the results.

ACS Style

Houman Hakima; M. Reza Emami. Deorbiter CubeSat mission design. Advances in Space Research 2021, 67, 2151 -2171.

AMA Style

Houman Hakima, M. Reza Emami. Deorbiter CubeSat mission design. Advances in Space Research. 2021; 67 (7):2151-2171.

Chicago/Turabian Style

Houman Hakima; M. Reza Emami. 2021. "Deorbiter CubeSat mission design." Advances in Space Research 67, no. 7: 2151-2171.

Article
Published: 14 December 2020 in Journal of Intelligent & Robotic Systems
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This paper proposes an adaptive tracking control scheme for multi-spacecraft formation with inter-collision avoidance, obstacle dodging, and connectivity preservation. The proposed scheme is distributed, i.e., each spacecraft only needs to communicate with its neighbours. Both connectivity preservation and distributed networking are critical features for small spacecraft formation with limited computation and communication capacities. New artificial potential functions are defined to preserve the connectivity of neighbour spacecraft while avoiding their inter-collision as well as collision with obstacles. An adaptive sliding-mode controller is designed for reaching and maintaining the predetermined formation configuration while satisfying the safety assurance requirements, including inter-collision avoidance, obstacle dodging, and connectivity preservation. The stability of the controller is proven through the Lyapunov analysis, in the presence of gravitational, solar radiation pressure, and atmosphere drag perturbations and dynamic uncertainties. The performance of the control scheme is demonstrated through several comparative simulation studies.

ACS Style

Zhongyuan Chen; M. Reza Emami; Wanchun Chen. Connectivity Preservation and Obstacle Avoidance in Small Multi-Spacecraft Formation with Distributed Adaptive Tracking Control. Journal of Intelligent & Robotic Systems 2020, 101, 1 -23.

AMA Style

Zhongyuan Chen, M. Reza Emami, Wanchun Chen. Connectivity Preservation and Obstacle Avoidance in Small Multi-Spacecraft Formation with Distributed Adaptive Tracking Control. Journal of Intelligent & Robotic Systems. 2020; 101 (1):1-23.

Chicago/Turabian Style

Zhongyuan Chen; M. Reza Emami; Wanchun Chen. 2020. "Connectivity Preservation and Obstacle Avoidance in Small Multi-Spacecraft Formation with Distributed Adaptive Tracking Control." Journal of Intelligent & Robotic Systems 101, no. 1: 1-23.

Journal article
Published: 20 October 2020 in Acta Astronautica
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This paper investigates the problem of concurrent rendezvous and attitude synchronization with a tumbling space debris. A novel formulation of the system dynamics model is first presented, based on image features and their rates, for the 6-degree-of-freedom relative pose tracking, which does not require an accurate estimation of the relative motions. Two image-based visual servoing schemes are then developed, which integrate visual navigation into the control law by defining state errors directly in the two-dimensional image space. The first scheme, i.e., observer-based controller, estimates the image rates without any need for relative velocity measurements. The second scheme, i.e., adaptive controller, updates the control gains by estimating the uncertainty terms in real time, hence eliminates the need for assigning their upper bounds a priori. The stability analysis of both controllers guarantees that the state errors remain uniformly ultimately bounded and exponentially converge to an arbitrarily small compact set containing the equilibrium point during the rendezvous and attitude synchronization mission. Numerical simulations and a comparative study with PD-like, image-based visual servoing are presented to validate the effectiveness and advantages of the proposed control schemes.

ACS Style

Xiangtian Zhao; M. Reza Emami; Shijie Zhang. Image-based control for rendezvous and synchronization with a tumbling space debris. Acta Astronautica 2020, 179, 56 -68.

AMA Style

Xiangtian Zhao, M. Reza Emami, Shijie Zhang. Image-based control for rendezvous and synchronization with a tumbling space debris. Acta Astronautica. 2020; 179 ():56-68.

Chicago/Turabian Style

Xiangtian Zhao; M. Reza Emami; Shijie Zhang. 2020. "Image-based control for rendezvous and synchronization with a tumbling space debris." Acta Astronautica 179, no. : 56-68.

Journal article
Published: 14 August 2020 in IEEE Transactions on Aerospace and Electronic Systems
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The paper discusses dynamic requirements for designing ground manipulator platforms that can be utilized to verify the performance of controllers developed for space manipulators. Dimensional analysis is used to formalize the dynamic equivalence conditions and control scaling laws between a given space manipulator and the ground manipulator to be designed, such that the space manipulator and the designed ground manipulator are dynamically equivalent. Given that, unlike its space counterpart, the ground manipulator may not have the complete six degrees of freedom for its base and it must function under the gravity effects, as well as manufacturing imprecisions in building the ground manipulator, the sensitivity of dynamic equivalence conditions to the above factors is analyzed. Further, an error compensation scheme based on the feedback linearization technique is developed to make the closed-loop ground manipulator have similar joint movements to those of the space manipulator under its controller. As a result, ground-based verification experiments can be performed for the controllers that will operate on the space manipulator. The design of a ground manipulator with the error compensation scheme for a specific space manipulator is illustrated through simulations, and it is shown how the performance of a PID controller for the space manipulator can be verified using the designed ground manipulator.

ACS Style

Lijun Zong; M. Reza Emami. Control Verifications of Space Manipulators Using Ground Platforms. IEEE Transactions on Aerospace and Electronic Systems 2020, 57, 341 -354.

AMA Style

Lijun Zong, M. Reza Emami. Control Verifications of Space Manipulators Using Ground Platforms. IEEE Transactions on Aerospace and Electronic Systems. 2020; 57 (1):341-354.

Chicago/Turabian Style

Lijun Zong; M. Reza Emami. 2020. "Control Verifications of Space Manipulators Using Ground Platforms." IEEE Transactions on Aerospace and Electronic Systems 57, no. 1: 341-354.

Original article
Published: 16 July 2020 in The Journal of the Astronautical Sciences
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This paper presents the mission concept and engineering design of a debris-removing nanosatellite called Deorbiter CubeSat, within the framework of NASA’s Pre-Phase A studies. The spacecraft is designed based on the utilization of an eight-unit form factor, and is intended for the removal of predetermined sizable debris objects from the low Earth orbit. A number of attitude and orbit determination sensors and control actuators are included on the CubeSat, which are employed during the rendezvous, attachment, and deorbiting operations. Upon attaching to a debris, the CubeSat stabilizes the rotational motion of the debris, and then proceeds to reducing the debris orbit size, in order to re-enter Earth’s atmosphere and burn up due to the high atmospheric density. The engineering design of Deorbiter CubeSat is outlined, and the selected components are detailed. The selected components are commercially available and have long space heritage. System’s mass budget is analyzed, and preliminary component costs are estimated. Three scenarios for the Deorbiter CubeSat mission operations are considered, and the spacecraft power budget and components duty cycles are investigated for each scenario. In light of the results, the feasibility of each scenario for the Deorbiter CubeSat mission is discussed.

ACS Style

Houman Hakima; M. Reza Emami. Deorbiter CubeSat System Engineering. The Journal of the Astronautical Sciences 2020, 67, 1600 -1635.

AMA Style

Houman Hakima, M. Reza Emami. Deorbiter CubeSat System Engineering. The Journal of the Astronautical Sciences. 2020; 67 (4):1600-1635.

Chicago/Turabian Style

Houman Hakima; M. Reza Emami. 2020. "Deorbiter CubeSat System Engineering." The Journal of the Astronautical Sciences 67, no. 4: 1600-1635.

Journal article
Published: 04 March 2020 in Aerospace Science and Technology
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This paper proposes a control method for space manipulators, involving concurrent operation of an optimal and a coordinated controller. The optimal controller moves center of mass of the base spacecraft to a desired position along an optimal rendezvous trajectory for minimizing the energy. The optimal control problem is solved through Calculus of Variations, using saturation functions to represent the physical limitations in thrust forces. The coordinated controller drives the arm end-effector to a desired pose (for rendezvousing with the target), as well as making the base attitude follow a desired profile. It also generates augmented reactive moments on the base spacecraft to ensure controlling its attitude when the base actuators reach their limits. Simulations of a realistic space manipulator model demonstrate the performance of the proposed concurrent control method.

ACS Style

Lijun Zong; M. Reza Emami. Concurrent base-arm control of space manipulators with optimal rendezvous trajectory. Aerospace Science and Technology 2020, 100, 105822 .

AMA Style

Lijun Zong, M. Reza Emami. Concurrent base-arm control of space manipulators with optimal rendezvous trajectory. Aerospace Science and Technology. 2020; 100 ():105822.

Chicago/Turabian Style

Lijun Zong; M. Reza Emami. 2020. "Concurrent base-arm control of space manipulators with optimal rendezvous trajectory." Aerospace Science and Technology 100, no. : 105822.

Research article
Published: 21 December 2019 in International Journal of Satellite Communications and Networking
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Communication systems are adopting all‐software architectures, because of their scalability, extensibility, flexibility, and cost‐effectiveness. This paper introduces a concurrent approach to the development and verification of baseband systems for satellite ground operations based on the behaviour‐driven development methodology. The open‐source GNU Radio development kit is used for developing the software‐defined radio baseband signal processing, as well as simulating the satellite and realistic channel impairments. The system performance at the end shows deviations of less than 1 dB with respect to the ideal performance and the Green Book standards specified by the Consultative Committee for Space Data Systems.

ACS Style

Moses B. Mwakyanjala; Cristóbal Nieto-Peroy; M. Reza Emami; Jaap Van De Beek. Concurrent development and verification of an all‐software baseband for satellite ground operations. International Journal of Satellite Communications and Networking 2019, 38, 209 -227.

AMA Style

Moses B. Mwakyanjala, Cristóbal Nieto-Peroy, M. Reza Emami, Jaap Van De Beek. Concurrent development and verification of an all‐software baseband for satellite ground operations. International Journal of Satellite Communications and Networking. 2019; 38 (2):209-227.

Chicago/Turabian Style

Moses B. Mwakyanjala; Cristóbal Nieto-Peroy; M. Reza Emami; Jaap Van De Beek. 2019. "Concurrent development and verification of an all‐software baseband for satellite ground operations." International Journal of Satellite Communications and Networking 38, no. 2: 209-227.

Journal article
Published: 06 December 2019 in Aerospace Science and Technology
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This paper details a concurrent attitude and orbit control method for a debris-removing nanosatellite, called deobriter CubeSat, during the rendezvous and synchronization maneuver with an uncontrollable tumbling debris object. The CubeSat is designed based on the utilization of an eight-unit form factor and commercially-available components with substantial space heritage, and is intended for the removal of sizable debris objects in low-Earth orbit. In particular, a low-thrust propulsion system is used for orbit control, as well as three reaction wheels allowing for a three-axis attitude control. Since the thruster can only produce force in one direction in the body frame, the spacecraft is considered to be underactuated. The controller employs the reaction wheels and the thruster to simultaneously rendezvous and synchronize the attitude of the CubeSat with the tumbling debris object, allowing for a concurrent attitude and position tracking. Detailed derivation of the concurrent controller is discussed, the effects of high-order derivatives are analyzed, and the stability of the system is proved. Simulation scenarios are created for two different thruster operation modes, namely, unsaturated thrust force and continuously-saturated thrust force, in order to verify the performance of the controller, as well as its robustness against gravity gradient disturbance torque and gravitational perturbation force.

ACS Style

Houman Hakima; M. Reza Emami. Concurrent attitude and orbit control for Deorbiter CubeSats. Aerospace Science and Technology 2019, 97, 105616 .

AMA Style

Houman Hakima, M. Reza Emami. Concurrent attitude and orbit control for Deorbiter CubeSats. Aerospace Science and Technology. 2019; 97 ():105616.

Chicago/Turabian Style

Houman Hakima; M. Reza Emami. 2019. "Concurrent attitude and orbit control for Deorbiter CubeSats." Aerospace Science and Technology 97, no. : 105616.

Journal article
Published: 02 October 2019 in Robotica
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SUMMARYThis paper studies the gait characteristics of a quadruped rover that mimics domestic cats, and attempts to optimize these characteristics. The kinematics and dynamics formulation of the rover’s three-dimensional model is developed, and its gait, pose and corresponding control parameters are computed to minimize torque or maximize speed, using a genetic algorithm. The optimization model consists of a set of equality and inequality constraints that ensure the feasibility and stability of the gaits, while considering the entire gait spectrum that feline species exhibit. The optimal gaits for minimizing the torque closely resemble lateral sequence gaiting, with a trotting behaviour as speed increases. A running gait is obtained at the maximum speed. The optimization results appear to conform to the biological observations of feline species, suggesting the tendency of conserving energy in biological gaiting.

ACS Style

Lukas Zhornyak; M. Reza Emami. Gait Optimization for Quadruped Rovers. Robotica 2019, 38, 1263 -1287.

AMA Style

Lukas Zhornyak, M. Reza Emami. Gait Optimization for Quadruped Rovers. Robotica. 2019; 38 (7):1263-1287.

Chicago/Turabian Style

Lukas Zhornyak; M. Reza Emami. 2019. "Gait Optimization for Quadruped Rovers." Robotica 38, no. 7: 1263-1287.

Journal article
Published: 09 August 2019 in IEEE Transactions on Aerospace and Electronic Systems
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This paper presents a new dynamic formulation as well as control scheme for space manipulators in order to drive the end-effector along a desired trajectory while minimizing the base disturbances caused by the arm movements. Through the new dynamic formulation, the end-effector is viewed as a Virtual Base, and the end-effector variables are also considered as generalized coordinates. As a result, joint controllers can be designed without having to solve for the inverse kinematics problem and computing the derivative of the generalized Jacobian matrix. Consequently, the joint control torque can be obtained analytically through the Lagrange multipliers method. Further, the joint control torque is also obtained through a quadratic programming problem in order to take into account the joint torque constraints. Several case studies are simulated to demonstrate the new control scheme and compare its performance with that of other controllers.

ACS Style

Lijun Zong; M. Reza Emami; Jianjun Luo. Reactionless Control of Free-Floating Space Manipulators. IEEE Transactions on Aerospace and Electronic Systems 2019, 56, 1490 -1503.

AMA Style

Lijun Zong, M. Reza Emami, Jianjun Luo. Reactionless Control of Free-Floating Space Manipulators. IEEE Transactions on Aerospace and Electronic Systems. 2019; 56 (2):1490-1503.

Chicago/Turabian Style

Lijun Zong; M. Reza Emami; Jianjun Luo. 2019. "Reactionless Control of Free-Floating Space Manipulators." IEEE Transactions on Aerospace and Electronic Systems 56, no. 2: 1490-1503.

Journal article
Published: 01 August 2019 in Applied Sciences
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The current success rate of CubeSat missions, particularly for first-time developers, may discourage non-profit organizations to start new projects. CubeSat development teams may not be able to dedicate the resources that are necessary to maintain Quality Assurance as it is performed for the reliable conventional satellite projects. This paper discusses the structured life-cycle of a CubeSat project, using as a reference the authors’ recent experience of developing and operating a 2U CubeSat, called qbee50-LTU-OC, as part of the QB50 mission. This paper also provides a critique of some of the current poor practices and methodologies while carrying out CubeSat projects.

ACS Style

Cristóbal Nieto-Peroy; M. Reza Emami. CubeSat Mission: From Design to Operation. Applied Sciences 2019, 9, 3110 .

AMA Style

Cristóbal Nieto-Peroy, M. Reza Emami. CubeSat Mission: From Design to Operation. Applied Sciences. 2019; 9 (15):3110.

Chicago/Turabian Style

Cristóbal Nieto-Peroy; M. Reza Emami. 2019. "CubeSat Mission: From Design to Operation." Applied Sciences 9, no. 15: 3110.

Article
Published: 10 May 2019 in The Journal of the Astronautical Sciences
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This article discusses a convex-optimization-based planning method for a geostationary satellite to determine station keeping and momentum unloading maneuvers concurrently. The proposed optimization algorithm incorporates a dual-rate prediction model to address the time scaling difference between the coupled slow orbital and fast attitude dynamics. The use of combined prediction model in the optimization problem facilitates to include state constraints accounting for the desired orbital and momentum unloading requirements. Maneuver plans are determined by solving a convex optimization problem in a receding horizon control form. The main objective of the proposed algorithm is to minimize fuel consumption while managing the stored momentum, in order to maintain a satellite in a tight station keeping window and nadir pointing attitude configuration. Numerical simulations are performed to validate the proposed optimization algorithm in terms of fuel consumption and constraint enforcement.

ACS Style

Sumeet Satpute; M. Reza Emami. Concurrent Station Keeping and Momentum Management of Geostationary Satellites. The Journal of the Astronautical Sciences 2019, 66, 341 -360.

AMA Style

Sumeet Satpute, M. Reza Emami. Concurrent Station Keeping and Momentum Management of Geostationary Satellites. The Journal of the Astronautical Sciences. 2019; 66 (3):341-360.

Chicago/Turabian Style

Sumeet Satpute; M. Reza Emami. 2019. "Concurrent Station Keeping and Momentum Management of Geostationary Satellites." The Journal of the Astronautical Sciences 66, no. 3: 341-360.

Article
Published: 25 April 2019 in International Journal of Technology and Design Education
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Cornerstone design courses have become a major part of engineering curricula, where students with different personality types and learning styles work together to design, develop, build, and demonstrate the functionality of a prototype within the duration of a term. This study analyzes student and team performance against gender, personality types, and learning styles in a second-year engineering design course. Further, the correlations between several assessment mechanisms are studied, and the effects of three different instructional design approaches on students’ performance are explored. Data have been collected on student performance and psychometrics, including marks, gender, personality type, and learning style from 2001 to 2018. To identify students’ personality types and learning styles, Myers–Briggs Type Indicators (MBTI) and Neil Fleming’s Learning VARK tests were administered. To evaluate students’ performance in the course, a number of assessment mechanisms have been defined. Several statistical methods are used to analyze data, and to determine correlation between datasets. Over nearly two decades of marks, gender, MBTI, and VARK data for 2637 students are presented for an engineering design course. The results demonstrated that there was no significant difference in performance across most assessments based on gender or gender distribution on a team. A better performance was observed from VK bimodal and quadmodal learning styles in most assessment mechanisms. Further, certain MBTI groups, namely, judging types outperformed their peers in engineering design assessments, with interesting interplay between MBTI dimensions for specific assessments and team dynamics. Traditional assessment mechanisms, such as engineering notebook and design proposals, are shown to be good predictors of student success. Lastly, scaffolded design activities and front-loading of lecture content were shown to be beneficial for student learning. There is negligible performance difference between female and male students in the engineering design course. Students whose preferred learning styles align with the assessment themes showed better performance in the course. The outcomes of this paper can be readily applied by instructors for design of assessment mechanisms, course materials, team formation, and instructional design.

ACS Style

M. Reza Emami; Michael C. F. Bazzocchi; Houman Hakima. Engineering design pedagogy: a performance analysis. International Journal of Technology and Design Education 2019, 30, 553 -585.

AMA Style

M. Reza Emami, Michael C. F. Bazzocchi, Houman Hakima. Engineering design pedagogy: a performance analysis. International Journal of Technology and Design Education. 2019; 30 (3):553-585.

Chicago/Turabian Style

M. Reza Emami; Michael C. F. Bazzocchi; Houman Hakima. 2019. "Engineering design pedagogy: a performance analysis." International Journal of Technology and Design Education 30, no. 3: 553-585.

Journal article
Published: 01 April 2019 in Advances in Space Research
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The ascent prediction of high-altitude zero-pressure stratospheric balloons is an important aspect of targeted test flight. Prediction of the balloon ascent rate is the prerequisite for many of the flights as it helps in planning ballasting and valving manoeuvres. In this paper, a standard analytical model, a fuzzy model and a statistical regression model are developed and compared to predict the zero-pressure balloon ascent. The flight data is extracted from the Esrange balloon service system for zero-pressure balloons with different payload capability, and several potential explanatory variables are computed for every sampled climbed segment. For the fuzzy modelling approach, a fuzzy c-mean clustering algorithm is used for system identification and prediction. For the regression approach, a Gaussian process regression is used, and principal component analysis is applied for finding the significant inputs. The result shows that the data driven approaches are more efficient than the standard analytical model.

ACS Style

Kanika Garg; M. Reza Emami. Balloon ascent prediction: Comparative study of analytical, fuzzy and regression models. Advances in Space Research 2019, 64, 252 -270.

AMA Style

Kanika Garg, M. Reza Emami. Balloon ascent prediction: Comparative study of analytical, fuzzy and regression models. Advances in Space Research. 2019; 64 (1):252-270.

Chicago/Turabian Style

Kanika Garg; M. Reza Emami. 2019. "Balloon ascent prediction: Comparative study of analytical, fuzzy and regression models." Advances in Space Research 64, no. 1: 252-270.

Article
Published: 01 March 2019 in The Journal of the Astronautical Sciences
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The control of a spacecraft equipped with a six-degree-of-freedom robot manipulator is studied in this paper. The objective is to rendezvous and synchronize with a satellite to facilitate inspection, servicing or de-orbiting. The space manipulator dynamics model with global parameterization on the configuration manifold is derived and used for designing asymptotically-stable control laws, so that they are valid globally in the configuration manifold. The control system consists of a sliding-mode rendezvous controller as well as a geometric attitude synchronization and a model-based servo control for the robot manipulator. The gains of the sliding-mode controller dictate a user-defined upper-bound on the thrust force. The attitude synchronization controller, concurrently with the rendezvous controller, is capable of micro-orbiting the space manipulator around spinning or tumbling satellites. It is observed through the simulations that the controller consumes limited amount of propellant, and it is feasible to use it for either a re-fueling (larger mass) or a de-orbiting (smaller mass) space manipulator.

ACS Style

Vijay Muralidharan; M. Reza Emami. Rendezvous and Attitude Synchronization of a Space Manipulator. The Journal of the Astronautical Sciences 2019, 66, 100 -120.

AMA Style

Vijay Muralidharan, M. Reza Emami. Rendezvous and Attitude Synchronization of a Space Manipulator. The Journal of the Astronautical Sciences. 2019; 66 (1):100-120.

Chicago/Turabian Style

Vijay Muralidharan; M. Reza Emami. 2019. "Rendezvous and Attitude Synchronization of a Space Manipulator." The Journal of the Astronautical Sciences 66, no. 1: 100-120.

Journal article
Published: 19 October 2018 in Acta Astronautica
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This paper details the development of a planning algorithm for multiple co-located geostationary satellites to perform station keeping and momentum unloading maneuvers concurrently. The objective is to minimize the overall fuel consumption while guaranteeing a safe separation distance between the satellites within a specific geostationary slot, as well as managing their stored angular momentum to maintain their nadir pointing orientation. The algorithm adopts the leader-follower architecture to define relative orbital elements of the satellites equipped with four gimbaled on-off electric thrusters, and solves a convex optimization problem with inequality constraints, including momentum unloading requirements, to determine the optimal maneuvers. The proposed algorithm is verified, in terms of fuel consumption, constraints enforcement and satellites performance, using numerical simulations that take into account dominant perturbations in the geostationary environment.

ACS Style

Sumeet Satpute; M. Reza Emami. Concurrent co-location maneuver planning for geostationary satellites. Acta Astronautica 2018, 163, 211 -224.

AMA Style

Sumeet Satpute, M. Reza Emami. Concurrent co-location maneuver planning for geostationary satellites. Acta Astronautica. 2018; 163 ():211-224.

Chicago/Turabian Style

Sumeet Satpute; M. Reza Emami. 2018. "Concurrent co-location maneuver planning for geostationary satellites." Acta Astronautica 163, no. : 211-224.

Journal article
Published: 11 September 2018 in Acta Astronautica
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In this work, an approach to designing near-optimal nonplanar transfer trajectories for asteroids is introduced, taking into account the uncertainty in asteroid parameters. The approach is demonstrated using a specific known Near-Earth Asteroid (NEA) as a model for the transfer scenario. The designed trajectory redirects the NEA from its current orbit about the Sun to a new orbit in the Earth-Moon system. The approach utilizes a low-thrust redirection method, namely the ion beam method, to execute the transfer; however, the work can be extrapolated to most low-thrust redirection methods. Asteroid parameters, such as absolute magnitude, albedo and density, are modelled, and a Monte Carlo analysis is employed to investigate the redirection maneuver in light of the expected variation in parameters. The trajectory transfer is modelled in three dimensions through the use of pseudo-equinoctial shaping, and is subsequently optimized. Due to the large design space created by the 21 decision variables, the optimization is parsed into two main steps; first, a global optimization that employs a genetic algorithm, followed by a local optimization that utilizes sequential quadratic programming to refine the result from the global optimization. Lastly, the results of the Monte Carlo analysis for the near-optimal trajectory transfer of the NEA are discussed.

ACS Style

Michael C.F. Bazzocchi; M. Reza Emami. Stochastic optimization of asteroid three-dimensional trajectory transfer. Acta Astronautica 2018, 152, 705 -718.

AMA Style

Michael C.F. Bazzocchi, M. Reza Emami. Stochastic optimization of asteroid three-dimensional trajectory transfer. Acta Astronautica. 2018; 152 ():705-718.

Chicago/Turabian Style

Michael C.F. Bazzocchi; M. Reza Emami. 2018. "Stochastic optimization of asteroid three-dimensional trajectory transfer." Acta Astronautica 152, no. : 705-718.

Journal article
Published: 01 August 2018 in Advances in Space Research
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ACS Style

Michael C.F. Bazzocchi; M. Reza Emami. Formation of multiple landers for asteroid detumbling. Advances in Space Research 2018, 62, 732 -744.

AMA Style

Michael C.F. Bazzocchi, M. Reza Emami. Formation of multiple landers for asteroid detumbling. Advances in Space Research. 2018; 62 (3):732-744.

Chicago/Turabian Style

Michael C.F. Bazzocchi; M. Reza Emami. 2018. "Formation of multiple landers for asteroid detumbling." Advances in Space Research 62, no. 3: 732-744.

Review article
Published: 01 June 2018 in Progress in Aerospace Sciences
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This paper presents a comprehensive review of the science and technology of accessing near-Earth asteroids (NEAs), or making them accessible, for obtaining both information and resources. The survey is divided into four major groups of NEA study, namely a) discovery (population estimation and detection), b) Exploration (identification and characterization), c) deflection and redirection, and d) mining (prospecting, excavation, processing, refining, storage.). Recent research and development advancements from both industry and academia are discussed in each group, and certain specific future directions are highlighted. Some concluding remarks are made at the end, including the need for creating new educational programs to train competent engineers and researchers for the taskforce in the new field of asteroid engineering in near future.

ACS Style

Niklas Anthony; M. Reza Emami. Asteroid engineering: The state-of-the-art of Near-Earth Asteroids science and technology. Progress in Aerospace Sciences 2018, 100, 1 -17.

AMA Style

Niklas Anthony, M. Reza Emami. Asteroid engineering: The state-of-the-art of Near-Earth Asteroids science and technology. Progress in Aerospace Sciences. 2018; 100 ():1-17.

Chicago/Turabian Style

Niklas Anthony; M. Reza Emami. 2018. "Asteroid engineering: The state-of-the-art of Near-Earth Asteroids science and technology." Progress in Aerospace Sciences 100, no. : 1-17.