Research Projects
Current Projects
Cable-Actuated Bio-inspired Lightweight Elastic Solar Sail (CABLESSail)
The goal of this NASA-sponsored project is to design and validate the Cable-Actuated Bio-inspired Lightweight Elastic Solar Sail (CABLESSail) concept for the attitude control of large, next-generation solar sails. The CABLESSail concept operates using lightweight cable-driven actuation to achieve controllable elastic solar sail deformations that induce an imbalance in solar radiation pressure and generate large, scalable control torques on the solar sail in all three axes.
Students: Keegan Bunker, Soojeong Lee, Ping-Yen Shen, Michael States,, Ryan Levendusky, Michael Dallalah
Previous Students: Nathan Raab, Niko Sexton, Austin Bodin, Chris Thacker
Funding: NASA Early Career Faculty Award
Publications:
S. Lee and R. J. Caverly "Robust Cable-Actuated Shape Control of a Flexible Solar Sail Boom for the CABLESSail Concept" AAS Guidance, Navigation and Control Conference, Breckenridge, CO, February 2-7, 2024, to appear.
K. R. Bunker and R. J. Caverly "Modular Dynamic Modeling and Simulation of a Cable-Actuated Flexible Solar Sail," AIAA/AAS Space Flight Mechanics Meeting, AIAA SciTech Forum, Orlando, FL, January 8-12, 2024, AIAA 2024-2436. [pdf]
R. J. Caverly, K. Bunker, N. Raab, V. L. Nguyen, G. Saner, Z. Chen, T. Douvier, R. J. Lyman, O. Sorby, B. Sorge, E. Teshale and B. Toriseva "Solar Sail Attitude Control Using Shape Modulation: The Cable-Actuated Bio-inspired Lightweight Elastic Solar Sail (CABLESSail) Concept," International Symposium on Space Sailing, New York, NY, June 5-9, 2023. [pdf]
Dissipativity-Based Control of Deployable Flexible Space Structures
The goal of this NASA-sponsored project is to develop the foundational theory for the control of large flexible space structues with on-the-fly system identification of uncertain or changing dynamics through the utilization of data-driven learning and robust control theory, specifically dissipativity theory.
Student: Logan Anderson
Funding: NASA Space Technology Graduate Research Opportunity (NSTGRO)
Image Credit: NASA
On-the-Fly Flight Test Maneuver Optimization and Nonlinear Modeling of Hypersonic Systems
The goal of this AFOSR-sponsored project is to develop a unified testing and evaluation approach for hypersonic flight systems that involves optimizing both the design of flight test maneuvers and the extraction of reliable control-oriented models.
Students: Sze Kwan (Jason) Cheah, Erik Lehner
Collaborators: Prof. Maziar Hemati, Dennis Van Dommelen, Dr. Diganta Bhattacharjee, Amir Enayati
Funding: Air Force Office of Scientific Research, UMII-MnDRIVE Graduate Assistantship.
Publications:
S. K. Cheah, B. Bhattacharjee, M. S. Hemati and R. J. Caverly "Control Synthesis for a Hypersonic Vehicle with Harmonic Excitation Inputs and Input-Output-Sampled Nonlinearities," AIAA Guidance, Navigation, and Control Conference, AIAA SciTech Forum, Orlando, FL, January 8-12, 2024, AIAA 2024-1589. [pdf]
S. K. Cheah*, D. Bhattacharjee*, M. S. Hemati and R. J. Caverly "Robust Local Stabilization of Nonlinear Systems with Controller-Dependent Norm Bounds: A Convex Optimization Approach with Input-Output Sampling," IEEE Control Systems Letters, Vol. 7, pp. 931-936, 2023. [pdf]
Optimal and Robust Control of Hard Disk Drives
This project focuses on applying optimal and robust control theory to the analysis and design of hard disk drives. Our goal is to improve the disturbance rejection performance of hard disk drives and ensure robustness to drive-to-drive manufacturing uncertainty.
Student: Erik Lehner
Previous Student: Manash Chakraborty
Funding: Seagate Technologies and the Center for Micromagnetics and Information Technologies (MINT).
Publications:
R. J. Caverly, M. Chakraborty, B. Huang and R. Sosseh "Robust Mixed H2-Hinf Control Synthesis for Dual-Stage Hard Disk Drives Using Convex Optimization," IFAC World Congress, Yokohama, Japan, July 9-14, 2023. Appears in IFAC-PapersOnline, Vol. 56, No. 2, pp. 10620-10625. [pdf]
M. Chakraborty and R. J. Caverly "Disturbance Modeling and Prediction of Closed-Loop Micro-Actuator Stroke Usage in Dual-Stage Hard Disk Drive," ASME Letters in Dynamic Systems and Control, Vol. 2, No. 4, p. 041003, 2022. [pdf]
Image Credit: Eric Gaba
Atmoshperic Adaptation for the Control of Mars Entry Vehicles
This project focuses on identifying variations in atmospheric density in real time during a Martian entry, with the goal of using this estimate to adapt the control of the entry vehicle to minimize deviation from a nominal guidance trajectory.
Student: Robert Halverson
Collaborator: Prof. Maziar Hemati
Previous Student: Ryleigh McGiveron
Funding: DoD SMART Scholarship
Publications:
R. D. Halverson, R. McGiveron, M. S. Hemati and R. J. Caverly "Towards Predictive Control with Atmospheric Adaptation for Martian Entry Systems" AAS Guidance, Navigation and Control Conference, Breckenridge, CO, February 2-7, 2024, to appear.
Predictive Control of a Dual-Spin Satellite with Magnetic Actuation
This project focuses on using attitude control of a CubeSat in a dual-spin-stabilized configuration using magnetic actuation, which requires only one reaction wheel and three magnetic torque rods. Predictive control is used to maintain the satellite within a specified pointing cone, while meeting actuator limits and minimizing control effort.
Student: Robert Halverson
Collaborator: Prof. Demoz Gebre-Egziabher
Funding: DoD SMART Scholarship
Publications:
R. D. Halverson, D. Gebre-Egziabher and R. J. Caverly "Attitude Control of Dual-Spin Satellites in Low-Earth Orbit via Predictive Control and Magnetic Actuation," AIAA/AAS Space Flight Mechanics Meeting, AIAA SciTech Forum, Orlando, FL, January 8-12, 2024, AIAA 2024-2278. [pdf]
Hypersonic Configurable Unit Ballistic Experiment (HyCUBE)
This AFOSR-sponsored project is centered around the design and analysis of HyCUBE: Hypersonic Configurable Unit Ballistic Experiment. HyCUBE is a CubeSat-like spacecraft that will perform a controlled de-orbit and re-enter Earth's atmosphere at hypersonic speed, collecting valuable aerothermodynamic data along the way. The ARDC Lab is responsible for designing the control algorithm for the vehicle's de-orbit using drag modulation and assessing dynamic stability during the atmospheric re-entry.
Collaborators: Prof. Demoz Gebre-Egziabher, Prof. Ellen Longmire, Dr. Ioannis Nompelis, Prof. Marien Simeni
Previous Student: Alex Hayes
Funding: Air Force Office of Scientific Research, UMII-MnDRIVE Graduate Assistantship.
Publications:
A. D. Hayes and R. J. Caverly "Tracking Error Recoverability Analysis for Drag-Modulated LEO Spacecraft Using Successive Convexification," AAS/AIAA Astrodynamics Specialist Conference, Big Sky, MT, August 13-17, 2023, AAS-23-345. [pdf]
A. D. Hayes and R. J. Caverly "Model Predictive Tracking of Spacecraft Deorbit Trajectories Using Drag Modulation," Acta Astronautica, Vol. 202, pp. 670-685, 2023. [pdf]
A. D. Hayes, R. J. Caverly, and D. Gebre-Egziabher "Atmospheric Density Estimation in Low-Earth Orbit for Drag-Modulated Spacecraft," AAS Guidance, Navigation and Control Conference, Breckenridge, CO, February 4-9, 2022. [pdf]
A. Hayes, I. Nompelis, R. J. Caverly, J. Mueller, and D. Gebre-Egziabher "Dynamic Stability Analysis of a Hypersonic Entry Vehicle with a Non-Linear Aerodynamic Model," Modeling and Simulation Technologies Conference, AIAA AVIATION, Reno, NV, June 15-19, 2020, p. 3201. [pdf]
Dynamic Modeling, Control, and Pose Estimation of Cable-Driven Parallel Robots
This project is concerned with cable-driven parallel robots (CDPRs), which are robotic systems where a payload/end-effector is driven by cables pulling on it (e.g., SkyCam, Arecibo Telescope). Our work focuses on three critical aspects of CDPR research:
Derivation of modular, low-order, high-fidelity dynamic models of flexible cable-driven robotic systems
Development of robust control methods for these systems.
Novel pose estimation techniques.
We are in the process of fabricating a small CDPR testbed that will be used to validate our proposed modeling, control, and pose estimation strategies. Stay tuned for developments on this testbed!
Current Students: Ryan Levendusky, Michael Dallalah, Michael States, Henry Mahnke.
Previous Students: Sze Kwan (Jason) Cheah, Vinh Nguyen, Alex Hayes, Tianxu Qin, Josh Mays, JP Heinzen, Tyler Douglas, Samir Patel, Neel Puri, Nathan Raab, Justin Dang, Jamie Lyman, Sam Prokott, Austin Bodin, Chris Thacker, Niko Sexton.
Funding: University of Minnesota, UMN Multicultural Summer Research Opportunities Program (MSROP), UMN Undergraduate Research Opportunities Program (UROP), UMII-MnDRIVE Graduate Assistantship.
Publications:
R. J. Caverly, S. K. Cheah, K. Bunker, S. Patel, N. Sexton and V. L. Nguyen "Online Self-Calibration of Cable-Driven Parallel Robots Using Covariance-Based Data Quality Assessment Metrics," ASME Journal of Mechanisms and Robotics, to appear. [pdf]
S. K. Cheah, A. Hayes and R. J. Caverly "Adaptive Passivity-Based Pose Tracking Control of Cable-Driven Parallel Robots for Multiple Attitude Parameterizations," IEEE Transactions on Control Systems Technology, Vol. 32, No. 1, pp. 202-213, 2024. [pdf]
R. J. Caverly, K. Bunker, S. Patel and V. L. Nguyen "Forward Kinematics and Online Self-Calibration of Cable-Driven Parallel Robots with Covariance-Based Data Quality Assessment," Sixth International Conference on Cable-Driven Parallel Robots, Nantes, France, June 25-28, 2023. Appears in Cable-Driven Parallel Robots: Proceedings of the 6th International Conference on Cable-Driven Parallel Robots, Mechanisms and Machine Series, Vol. 132, Cham, Switzerland, Springer International, pp. 369-380, 2023. [pdf]
N. Raab, A. Lamperski and R. J. Caverly "Trajectory Generation of a Cable-Driven Parallel Robot for Aerial Videography and Dynamic Workspace Optimization," CCToMM Mechanisms, Machines, and Mechatronics Symposium, Quebec City, Canada, June 19-20, 2023, P11. [pdf]
R. J. Lyman, S. K. Cheah and R. J. Caverly "Noncolocated mu-Tip Trajectory Tracking of Redundantly-Actuated Flexible Robotic Manipulators," American Control Conference, San Diego, CA, May 31 - June 2, 2023, pp. 4671-4676. [pdf]
S. Patel, V. L. Nguyen and R. J. Caverly "Forward Kinematics of Cable-Driven Parallel Robots with Pose Estimation Error Covariance Bounds," Mechanism and Machine Theory, Vol. 183, p. 105231, 2023. [pdf]
N. Puri and R. J. Caverly "Coupled Least-Squares Forward Kinematics and Extended Kalman Filtering for the Pose Estimation of a Cable-Driven Parallel Robot," International Journal of Mechanisms and Robotic Systems, Vol. 5, No. 3, pp. 270-289, 2023. [pdf]
N. Puri and R. J. Caverly "Pose Estimation of a Cable-Driven Parallel Robot Using Kalman Filtering and Forward Kinematics Error Covariance Bounds," USCToMM Symposium on Mechanical Systems and Robotics, Rapid City, SD, May 19-21, 2022. Appears in USCTOMM Symposium on Mechanical Systems and Robotics, Mechanisms and Machine Science Series, Vol. 118, Cham, Switzerland, Springer International, 2022, pp. 65-75. [pdf]
V. L. Nguyen and R. J. Caverly "Cable-Driven Parallel Robot Pose Estimation using Extended Kalman Filtering with Inertial Payload Measurements," IEEE Robotics and Automation Letters, Vol. 6, No. 2, pp. 3615-3622, 2021. Presented at IEEE International Conference on Robotics and Automation (ICRA), Xi'an, China, May 30 - June 5, 2021. [pdf]
V. L. Nguyen and R. J. Caverly "CDPR Forward Kinematics With Error Covariance Bounds For Unconstrained End-Effector Attitude Parameterizations," Fifth International Conference on Cable-Driven Parallel Robots, Virtual Conference, July 7-9, 2021. Appears in Cable-Driven Parallel Robots: Proceedings of the 5th International Conference on Cable-Driven Parallel Robots, Mechanisms and Machine Science Series, Vol. 104, Cham, Switzerland, Springer International, 2021, pp. 37-49. [pdf]
S.-K. Cheah and R. J. Caverly "Passivity-Based Pose Regulation and Jacobian-Based Force Distribution of a Cable-Driven Parallel Robot," American Control Conference, New Orleans, LA, May 26-28, 2021, pp. 123-128. [pdf]
A. Hayes and R. J. Caverly "Passivity-Based Control Allocation of a Redundantly-Actuated Parallel Robotic Manipulator with a Point-Mass Payload," American Control Conference, Denver, CO, July 1-3, 2020, pp. 2432-2437. [pdf]
A Low-Cost and Low-Risk Testbed for Control Design of Launch Vehicles and Landing Systems
This project focuses on designing and building a quadrotor-based testbed to test advanced launch vehicle controllers in a low-cost and low-risk environment. Dynamic modeling is used to validate the similitude of the proposed testbed to a full-scale launch vehicle.
Students: James Johnson
Previous Students: Liam Elke, Will Roslansky, Keegan Bunker, Ethan Kolby
Collaborator: Prof. Demoz Gebre-Egziabher
Funding: NASA Office of STEM Engagement Fellowship
Publications:
W. J. Elke*, J. Johnson, W. Roslansky, D. Gebre-Egziabher and R. J. Caverly "Design, Fabrication, and Flight of the Cost- and Risk-Reducing Quadcopter System for GNC Testing" AAS Guidance, Navigation and Control Conference, Breckenridge, CO, February 2-7, 2024, to appear.
W. J. Elke and R. J. Caverly "Dynamics, Guidance, and Control of a Conceptual Low-Cost Testbed for Validating Space Vehicle GNC Algorithms," AIAA Guidance, Navigation, and Control Conference, AIAA SciTech Forum, Orlando, FL, January 8-12, 2024, AIAA 2024-0778. [pdf]
W. J. Elke, J. Pei, R. J. Caverly and D. Gebre-Egziabher "A Low-Cost and Low-Risk Testbed for Control Design of Launch Vehicles and Landing Systems," IEEE Aerospace Conference, Virtual Event, March 6-13, 2021. [pdf]
Station Keeping of Satellites in an Areostationary Mars Orbit
This project uses model predictive control techniques to minimize the delta-v required to maintain a satellite in an Areostationary Mars Orbit at different longitudes. This work provides insight into the feasibility of maintaining Areostationary satellite constellations for communication on the Martian surface.
Students: Robert Halverson and Nathan Gall
Previous Student: Gabriel Lundin
Collaborator: Dr. Avishai Weiss
Funding: Mitsubishi Electric Research Laboratories, UMN Undergraduate Research Opportunities Program (UROP).
Publications:
R. D. Halverson, A. Weiss and R. J. Caverly "A Comparison of Linear Quadratic and Nonlinear Model Predictive Control Applied to Station Keeping of Satellites in Areostationary Mars Orbits," AIAA Guidance, Navigation, and Control Conference, AIAA SciTech Forum, National Harbor, MD, January 23-27, 2023, AIAA 2023-2000. [pdf]
R. D. Halverson, A Weiss and R. J. Caverly "Station Keeping of Satellites in Areostationary Mars Orbit using Model Predictive Control," AAS/AIAA Space Flight Mechanics Meeting, Virtual Event, February 1-4, 2021, AAS 21-358. [pdf]
Previous Projects
Real-Time Modeling and Simulation of Space Vehicles with Fuel Slosh
The objective of this project is to develop and validate an accurate and computationally-efficient method to simulate the effects of fuel slosh on spacecraft motion. The proposed modeling method will allow for rapid testing and evaluation of spacecraft maneuvers in the presence of fuel slosh, which is an area of research in need of development as space operations become more prevalent and complex in the coming decades. Modern numerical simulation techniques will be used to derive and develop a general simulation software that can accommodate a range of mission scenarios and vehicle configurations.
Students: Liam Elke and Ping-Yen Shen
Collaborator: Prof. Demoz Gebre-Egziabher
Funding: NASA Office of STEM Engagement Fellowship, Office of the Vice President for Research - University of Minnesota.
Publications:
W. J. Elke and R. J. Caverly "Recreation of an Apollo-Era Separation Anomaly using a Low-g Slosh Mechanical Analog" AAS Guidance, Navigation and Control Conference, Breckenridge, CO, February 2-7, 2024, to appear.
W. J. Elke, J. Pei, C. M. Roithmayr and R. J. Caverly "Framework for Analyzing the Complex Interactions Between Spacecraft Motion and Slosh Dynamics in Log-G Environments," International Astronautical Congress, Paris, France, September 18-22, 2022. [pdf]
Extension of Robust Control Techniques for UAS Adaptive Control Systems
The goal of this project is to extend robust control techniques to be able to leverage knowledge of stochastic parameter variation. This additional insight will provide improved performance without sacrifice to robust stability.
Student: Logan Anderson
Collaborator: Prof. Andrew Lamperski
Funding: Honeywell International
Publications:
R. J. Caverly and V. L. Bageshwar "State Feedback Synthesis for Robust Performance with Probabilistic Uncertainty," American Control Conference, Toronto, ON, Canada, July 10-12, 2024, to appear. [pdf]
Control of Autonomous Aerial Vehicles: A Data-Driven Approach to Bridge the Gap Between Theory and Practice
The goal of this seed grant is to derive and validate foundational theory for the control of autonomous aerial vehicles with quick, on-the-fly adaptation to failures.
Student: Logan Anderson
Collaborator: Prof. Andrew Lamperski
Funding: University of Minnesota Institute for Informatics - MnDRIVE
Publications:
L. Anderson, R. J. Caverly and A. Lamperski "Statistical Bounds on Identified QSR Dissipative Properties from Input-Output Data," American Control Conference, Toronto, ON, Canada, July 10-12, 2024, to appear. [pdf]
L. Anderson, R. J. Caverly and A. Lamperski "Gain-Scheduled QSR-Dissipative Systems: An Input-Output Approach," American Control Conference, San Diego, CA, May 31 - June 2, 2023, pp. 2417-2423. [pdf]
Conic-Sector-Based Aeroelastic Control
This project uses the conic sector theorem to design gain-scheduled feedback controllers for aeroelastic system, which feature challenging, nonlinear, uncertain dynamics. Our work focuses on using the conic sector theorem to guarantee robust closed-loop input-output stability, while ensuring optimality throughout the flight envelope using a gain-scheduled approach.
Students: Logan Anderson, Jacob Brown
Funding: University of Minnesota, UMN Undergraduate Research Opportunities Program (UROP).
Publications:
J. J. Brown and R. J. Caverly "Gain-Scheduled-Conic-Sector-Based Robust Control of an Aeroelastic Airfoil," AIAA Guidance, Navigation, and Control Conference, AIAA SciTech Forum, Virtual Event, January 11-15 & 19-21, 2012, AIAA 2021-1562. [pdf]
Robust Trajectory Tracking Control of a Tower Crane
This project involves the dynamic modeling and passivity-based adaptive trajectory tracking control of a tower crane. We have developed a tower crane controller that can track payload trajectories in three dimensions and is robust to substantial model uncertainty and the nonlinearities associated with three-dimensional tower crane dynamics.
Students: Ping-Yen Shen and Julia Schatz
Funding: Study grant from Chung-Cheng Institute of Technology, National Defense University, Taiwan.
Publications:
J. Schatz and R. J. Caverly "Payload Trajectory Tracking of a 5-DOF Tower Crane with a Varying-Length Hoist Cable: A Passivity-Based Adaptive Control Approach," Mechatronics, Vol. 94, p. 103027, 2023. [pdf]
J. Schatz and R. J. Caverly "Passivity-Based Adaptive Control of a 5-DOF Tower Crane," IEEE Conference on Control Technology and Applications, San Diego, CA, August 8-11, 2021, pp. 1109-1114.
P.-Y. Shen, J. Schatz and R. J. Caverly "Passivity-Based Adaptive Trajectory Control of an Underactuated 3-DOF Overhead Crane," Control Engineering Practice, Vol. 112, p. 104805, 2021. [pdf]
P.-Y. Shen and R. J. Caverly "Noncolocated Passivity-Based Control of a 2DOF Tower Crane with a Flexible Hoist Cable," American Control Conference, Denver, CO, July 1-3, 2020, pp. 5046-5051. [pdf]
Optimal Synthesis of Strictly Negative Imaginary (SNI) Controllers
This project focuses on convex methods to optimally synthesize strictly negative imaginary (SNI) controllers. Negative imaginary (NI) stability theory can be used to design SNI feedback controllers that robustly stabilize systems with NI properties (e.g., beams, flexible robotic systems). Our work focused on developing optimal SNI controllers with respect to H2 and H-infinity metrics.
Student: Manash Chakraborty
Funding: University of Minnesota
Publications:
R. J. Caverly and M. Chakraborty "Optimal Synthesis of a Strictly Negative Imaginary Feedback Controller," IEEE Conference on Decision and Control, Nice, France, Dec. 11-13, pp. 7578-7583. [pdf]
Optimal Open-Loop Output Modification
This project involved the development of techniques that modify an open-loop system to give it prescribed open-loop properties. One example of this is parallel feedforward control, which modifies the output of the open-loop system to render it minimum phase or positive real. Other possible approaches involve optimally combining actuators and/or sensors to ensure desired open-loop system properties. We were able to show a benefit of using parallel feedforward control for noncolocated attitude control of a spacecraft's flexible appendage.
Student: Robert Halverson
Funding: UMN Undergraduate Research Opportunities Program (UROP)
Publications:
R. J. Caverly "Optimal Linear Combination of Sensors and Actuators to Enforce an Interior Conic Open-Loop System," International Journal of Robust and Nonlinear Control, Vol. 29, No. 17, pp. 6288-6310, 2019. [pdf]
R. D. Halverson and R. J. Caverly "Attitude Control of a Spacecraft Flexible Appendage using Parallel Feedforward Control," AIAA/AAS Space Flight Mechanics Meeting, AIAA SciTech Forum, Orlando, FL, Jan. 6-10, 2019, p. 716. [pdf]