Sajjadi-Kia S.,SySense, Inc. |
Jabbari F.,University of California at Irvine
Proceedings of the 2010 American Control Conference, ACC 2010 | Year: 2010
This note considers adding a measure of scheduling to the popular Anti-windup design for linear systems with saturating actuators. The main idea is to develop a scheduling scheme in which the anti-windup gains used depend on how much the actuator command exceeds the saturation bound. We present preliminary results for static Anti-windup gains, along with the convex synthesis LMIs, for the case of having two levels of saturation: moderate and severe. Benefits of the proposed design method over the traditional single gain Anti-Windup compensation are demonstrated using a well-known example. © 2010 AACC.
Chen R.H.,Northrop Grumman |
Speyer J.L.,SySense, Inc. |
Speyer J.L.,University of California at Los Angeles |
Lianos D.,U.S. Army
Journal of Guidance, Control, and Dynamics | Year: 2010
In the linear-quadratic pursuit-evasion game, the pursuer (interceptor) wishes to minimize the terminal miss, whereas the evader (target) wishes to maximize it. Therefore, the optimal strategy of the interceptor is derived against the anticipated worst possible strategy of the target. If the interceptor has a lag, the current approach is to include this lag directly in the system dynamics, which are known to both players. In this problem formulation, the optimal cost could easily go to infinity, which means that the target will win the game. This is expected, because the target has knowledge about interceptor's lag. To ensure the existence of an interceptor strategy, the weighting on the terminal miss has to be chosen small enough so that the optimal cost will remain finite. However, this manipulation prevents the target from maximizing the terminal miss and effectively constrains the target strategy. Therefore, the interceptor strategy is derived against the worst-case target strategy that is not really the worst case. In this paper, it is shown that this interceptor strategy performs poorly in realistic situations where the target tries to maximize the terminal miss. Instead, two new interceptor strategies are derived against target strategies that are determined without knowledge about the interceptor's lag. These two optimal interceptor strategies improve the game-theoretic guidance law for homing missiles by correctly taking into account the autopilot lag. © 2010 by Robert H. Chen.
Jin H.,Xiamen University |
Chang M.W.,SySense, Inc. |
Safonov M.G.,University of Southern California
Asian Journal of Control | Year: 2014
Given a feedback control system with an unknown plant, the problem of choosing a stabilizing controller is considered. Working within the framework of unfalsified adaptive control, we consider a finite-dimensional linear time invariant system as a special case of the standard adaptive configuration. A fading memory cost function is presented in which the influence of older data is reduced exponentially. With this cost function, the location of the poles can be detected with only input-output data. Compared with existing results, the cost function can detect changes affecting stability sooner and be used in adaptive switching control to improve the performance of controller switching. © 2013 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society.
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 99.50K | Year: 2011
SySense, Inc. proposes to adapt fault detection methodologies developed for the Data Acquisition and Error Budget Analysis Tools (DAEBAT) SBIR effort to the integrity management of Unmanned Air Vehicle Systems (UAVS). In Phase I, a set of integrity monitors will be developed to detect measurement faults in individual sensors and when redundant data is available, parity checks will be performed to detect faults between sources. A trade study will be conducted to develop the architecture of a model-based fault detection and isolation filter for a specific UAVS application such as Sense and Avoid. In a Phase II effort, the sensor monitors developed in Phase I will be implemented as Simulink real-time nodes capable of running on flight hardware. In addition, the model-based fault detection filter studied in Phase I will be developed, integrated, and validated through simulation BENEFIT: This software has applications to many safety critical processes such as those in the automotive, aerospace, and automation industries. Integrity monitors could be installed in automobile stability control systems to monitor for defective sensors. Future applications of an automated highway would require such safety features to ensure passenger safety. The applications within the aerospace industry are large and include engine monitoring, navigation systems assurance, and health monitoring for formation flight clusters.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.85K | Year: 2011
This proposal is for the development a fault detection and isolation (FDI) algorithm for a formation of satellites but processed at a ground station. The algorithm will be capable of operating when measurement data is available on an intermittent basis. An FDI algorithm for faults in the three translational and rotational modes of 4 satellites flying in formation in a highly elliptical orbit will be designed during the Phase 1 effort. The satellites will carry a limited suite of instruments, just sufficient to determine faults in the three translational and rotational modes and include a GPS receiver. Communication with a ground station will only be available near perigee. The measurement data is not stored and transmitted in bursts, so these communication blackouts represent a break in the time history of measurements. The proposed development will mitigate these breaks so that fault detection and isolation can be performed faster than in a simple, cyclical restart implementation. Furthermore, their elliptical orbit will carry the satellites beyond the GPS constellation. The proposed development will account for the loss of GPS coverage as well investigate ways of extending the useful of GPS (when signals are weak) for fault detection and isolation.
Agency: Department of Defense | Branch: Missile Defense Agency | Program: STTR | Phase: Phase II | Award Amount: 999.89K | Year: 2012
The proposed effort will further refine the adaptive model-based estimation and control guidance law developed during the Phase 1 effort to work in a two-tier algorithm with an agile, game-theoretic guidance law that is immune to the acceleration of the target. The two-tier approach is used to bring the intercept vehicle close to the target while conserving fuel but still obtains good minimal miss-distance performance. The first tier guidance uses a model-based estimation filter to anticipate where the ascending missile will be and rapidly detect staging. Using a model allows the interceptor to guide itself with some sense of fuel conservation. It also allows for an accurate time-to-go estimate. The terminal guidance law makes use of an estimation filter which blocks the target acceleration. This guidance is highly sensitive to target maneuvers, but makes no effort to conserve fuel. The criterion to switch between the two tiers will be investigated in this proposal.
Agency: Department of Defense | Branch: Defense Advanced Research Projects Agency | Program: SBIR | Phase: Phase I | Award Amount: 148.02K | Year: 2011
The objective of this proposal is to demonstrate a mobile application capable of determining the location of a remote target. When a photo is taken with a GPS-enabled camera, the GPS location of the actual camera is appended to the photo in a process known as Geo-Tagging. Remote Geo-Tagging (RGT) differs from this process in that RGT determines the coordinates of a target within the picture as opposed to the location from where the picture was taken, only using the embedded sensors within a smartphone. This allows a user to determine the GPS coordinates of a target without the need for single-purpose ranging equipment, referencing the target on a map, or needing to physically travel to the object with a GPS receiver. As conceived, the RGT application will be especially effective in homogenous environments, lacking in landmarks or other identifying features that can be referenced on a map. RGT has the potential to increase the accuracy of intelligence gathering and field reporting systems without the addition of major hardware, software, or other resources. In the commercial realm, RGT would enhance the social networking experience by making it easier to share the location of interesting objects, such as climbable rock faces.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 789.19K | Year: 2014
SySense, Inc. proposes to develop a framework for the design and implementation of fault detection and isolation (FDI) systems. The framework will include protocols which define how to work with an end customer so that an FDI system may be developed for a wide range of autonomous satellite, rocket, air, land, and underwater vehicle missions. The framework will define what kinds of data and information are needed a priori in order to design the FDI system, what kinds of mission requirements can be answered with the system, and how the system should be implemented in order to meet those requirements. The framework will also include the procedure to facilitate the efficient integration of our FDI methodology into both existing and planned systems. Clearly defining the FDI design process through this framework will make the technology more accessible to mission designers and lower the cost of implementation, providing more opportunities to apply this technology. The efficacy of the framework will be confirmed by designing and implementing collocated and non-collocated FDI systems for a representative satellite mission. The framework will also include introductory tutorial material designed for mission planners.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 124.99K | Year: 2013
This proposal is for the development of a dynamic fault detection filter for a formation of satellites operating in a highly nonlinear dynamic environment but processed at a ground station where measurement data may be available on an intermittent basis. A previous SBIR study demonstrates that nonlinearities have an adverse effect on a linear dynamic filter's ability to accurately declare faults. Thus, a fault detection filter capable of effectively accounting for nonlinear dynamics and measurement data interruptions is required. During the proposed Phase I effort, such filters will be designed for faults in the three translational modes of 4 satellites flying in formation near a highly elliptical orbit. The satellites will carry a limited suite of instruments, just sufficient to determine faults in the three translational modes and include a GPS receiver. Furthermore, communication with a ground station will only be available near perigee and the measurement data will be transmitted in bursts, which will introduce planned and unplanned communication blackouts that represent breaks in the time history of measurements. The proposed development will produce a fault detection and isolation algorithm that can mitigate these breaks and perform faster than a simple, cyclical restart implementation.
Agency: Department of Defense | Branch: Defense Advanced Research Projects Agency | Program: SBIR | Phase: Phase II | Award Amount: 368.28K | Year: 2012
The objective of this proposal is to develop a field tested, end-user referenced, production ready suite of applications for a smartphone device to perform Remote Geo-Tagging and sharing that information with an information network and other smart phones. Remote Geo-Tagging is the tagging of the target"s coordinates to images (of the same target) instead of simply tagging the location of the camera when the picture is taken. This allows a user to determine the GPS coordinates of a target without the need for single-purpose ranging equipment, referencing the target on a map, or needing to physically travel to the object with a GPS receiver. In Phase I, a proof-of-concept App was developed that used the GPS receiver, camera, and magnetometer embedded in the smartphone. In Phase II, the proof-of-concept code is rewritten into a production code and tested with military users during development. The final software suite will provide functionality to share target coordinates with a network and other smartphones.