Research: Aerospace and Maritime
Autonomous Underwater Vehicles

Advances in sensing and computational capabilities have enabled autonomous vehicles to become vital assets across multiple disciplines. These improved capabilities have led to increased interest in autonomous marine craft. As the technologies of these vehicles mature, there is a desire to improve the performance of their motion control systems so that these vehicles can better achieve their mission objectives. Path planning, station keeping, and path following are critical control objectives of marine craft that enable autonomous docking, surveying, etc. Improving the performance of these control objectives for marine craft directly correspond to improved range, endurance, accuracy, and robustness in different environmental conditions. NCR research efforts focus on various nonlinear control methods to achieve trajectory tracking, path following application in the presence of unknown currents. Efforts also focus on how to achieve these objectives in an optimal manner despite uncertainties and nonlinearities associated with the vehicle and the environment, including unknown obstacles.

Results for RISE-based tracking control in a swimming pool

Autonomous Surface Vehicle

Control of marine craft, such as commercial and government ships or autonomous surface vessels (ASV), remains an important research topic because of the many organizations that use waterways, e.g., shipping across oceans, mapping rivers, or protecting borders. In many of these scenarios, the model used for control of the marine craft may be uncertain. Rigid body and hydrodynamic parameters, i.e., added mass, centripetal-Coriolis effects, and drag, may be difficult to calculate. NCR research efforts focus on the development of control methods that are capable of compensating for model uncertainties through robust and adaptive control methods.

Autonomous Air Vehicles

Research efforts in this area are focused on agile flight domains where nonlinear dynamics are prevalent. In additional to such flight regimes, efforts focus on uncertain flight characteristics. In particular, the control influence matrix depends on the flight conditions. Efforts have focused on adaptive approaches to compensate for the uncertain nonlinear state-dependent dynamics.

Small Satellites

Due in part to the costs associated with launching large, heavy payloads into space, the space industry is moving toward smaller satellites and the technology to support them. Some proposed uses of these small satellites (small-sats) include astrophysics research, surveillance, and autonomous servicing, all of which require precision attitude motion. However, due to their smaller sizes, the attitude motion of these small-sats is more susceptible to external disturbances than their larger counterparts. Furthermore, the smaller sizes of these new small-sats limit the mass, power and size budgets allocated to their attitude control systems (ACS). These contradictory requirements necessitate novel solutions for the ACS. For small-sats, the desired torques are typically generated by a cluster of single gimbal control moment gyroscopes (CMGs) due to their low mass and low power consumption properties. Unfortunately, the torque producing capacity of CMGs can deteriorate over time due to changes in the dynamics such as bearing degradation and increased friction in the gimbals. Nonlinear adaptive attitude controllers are developed in this research to compensate for time-varying uncertain satellite inertia, nonlinear disturbances, and uncertain CMG gimbal friction and electromechanical CMG disturbances. A uniformly ultimately bounded (UUB) stability result is proven via Lyapunov analysis for the case in which static and dynamic friction effects and nonlinear electromechanical disturbances are included in the CMG dynamic model.

Hypersonic Vehicles

Hypersonic flight remains a challenging and rewarding field of aerospace technology research. Using scramjet engines and flying beyond Mach 5 pose a number of unique challenges not encountered by traditional aircraft. Such challenges include highly nonlinear aerothermoelastic effects. During hypersonic flight, speeds are high enough that there is a significant heating due to the compressed atmosphere. As the temperature of the aircraft's structure changes so too do the flight characteristics. NCR is investigating these nonlinear aerodynamic, thermal, and elastic effects and their interactions with structural and flight dynamics. By using nonlinear control methodologies developed in our lab, we have been able to show pitch-rate tracking stability in the presence of unknown and time-varying aerothermoelastic effects. Using Lyapunov-based stability analysis and simulation verification, our nonlinear controllers are able to robustly adapt to the continuously changing environment encountered during hypersonic flight.

Image-Based Guidance Navigation and Control

Image-based feedback can provide aerospace vehicle with extended mission capabilities. For example, imaging sensors are used for search and rescue, moving-target tracking, immediate bomb damage assessment, and identification and localization of interesting ground structures. Often air vehicles may need to operate in adverse environments, such as complex urban terrains where GPS may not be available. The speed of an aeronautical vehicle and the unstructured nature of the viewed scene present challenges for image-based navigation. NCR research efforts address such challenges by developing methods to keep feature in the camera field-of-view (FOV) and providing robustness when they do leave the FOV through observers and image geometry.

Limit Cycle Oscillations

In modern fighter aircraft, limit cycle oscillations (LCO) manifest as an anti-symmetric, non-divergent periodic twisting and bending motion of the wings. LCO can affect the pilot's ability to perform tasks such as reading gauges and the heads up display (HUD). Typical solutions involve avoiding certain flight conditions and delaying the release of ordnance. The objective of this project is to develop a control strategy that augments current flight controllers to suppress LCO behavior while remaining robust to modeling uncertainties and exogenous disturbances.

Biomimetic Approaches to Flight Control and Inertial Stabilization

Natural systems have evolved very robust solutions to highly complex problems. Large numbers of simple low fidelity sensors are typical, rather than sophisticated highly optimized single sensors. Sensor fusion, deriving measurements from multiple sensor modalities is common, for example, using both visual and inertial sensing simultaneously to measure body angular rate. The goal of this research is to learn from nature robust solutions to feedback control problems that might not have normally been considered following the traditional paradigm of engineering design. Current activities are focusing on insects to understand how inertial measurement occurs for flight stabilization. Gyroscopic sense organs called halteres are being simulated to understand how insects reconstruct 3 orthogonal components of the inertial rate vector using very simple fields of strain sensors. 6DOF flight simulations are also being constructed to reveal how extremely dynamic flight maneuvers and complex navigation solutions result from fusion of visual, inertial, and olfactory feedback.


Ongoing Projects
AFOSR: Center of Excellence in Assured Autonomy in Contested Environments
AFOSR: A Switched Systems Approach for Navigation and Control with Intermittent Feedback
NSF: Adaptive dynamic programming for uncertain nonlinear systems through coupling of nonlinear analysis and data-based learning
AFRL: Privileged Sensing Framework
ONR: Mine Counter Measure Path Planning and Optimal Control in Uncertain and Dynamic Maritime Environments

Completed Projects
Prioria: Observer Methods for Image Based Autonomous Navigation
Florida High Corridor Matching Funds

ONR: Adaptive Dynamic Programming for Autonomous Underwater Vehicles
AFOSR: Research Institute for Autonomous Precision Guided Systems
DARPA: Symbiosis of Micro-Robots for Advanced In-Space Operations
Innovative Automation Technologies Inc: Micro Air Vehicle Tether Recovery Apparatus (MAVTRAP): Image-based MAV Capture and Tensegrity System
AFRL: Vision-Based Guidance and Control Algorithms Research
UCF: Image-Based Motion Estimation and Tracking for Collaborative Space Assets
AFRL: Simultaneous Localization and Mapping
UF: Conceptual Design Study for a Remote Sensing Nanosatellite Mission
Prioria: Structure, Motion, and Geolocation Estimation for Autonomous Vehicles
AFOSR: Active Vision for Control of Agile Autonomous Flight
Florida High Corridor Matching Funds

Related NCR Aerospace and Maritime Systems Publications