Performance Measurements for a 1:6 Scale Model of the DOE Reference Model 2 (RM2) Cross-Flow Hydrokinetic Turbine.
Abstract not provided.
Wosnik, Martin↗
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A Nonlinear Dynamic Inversion Predictor-Based Model Reference Adaptive Controller for a Generic Transport Model
Presented here is a Predictor-Based Model Reference Adaptive Control (PMRAC) architecture for a generic transport aircraft. At its core, this architecture features a three-axis, non-linear, dynamic-inversion controller. Command inputs for this baseline controller are provided by pilot roll-rate, pitch-rate, and sideslip commands. This paper will first thoroughly present the baseline controller followed by a description of the PMRAC adaptive augmentation to this control system. Results are presented via a full-scale, nonlinear simulation of NASA s Generic Transport Model (GTM).
Campbell, Stefan F.↗
Improved reference models for middle atmosphere ozone
Improvements are provided for the ozone reference model which is to be incorporated in the COSPAR International Reference Atmosphere (CIRA). The ozone reference model will provide considerable information on the global ozone distribution, including ozone vertical structure as a function of month and latitude from approximately 25 to 90 km, combining data from five recent satellite experiments (Nimbus 7 LIMS, Nimbus 7 SBUV, AE-2 SAGE, Solar Mesosphere Explorer (SME) UVS, and SME IR). The improved models are described and use reprocessed AE-2 SAGE data (sunset) and extend the use of SAGE data from 1981 to the period 1981-1983. Comparisons are shown between the ozone reference model and various nonsatellite measurements at different levels in the middle atmosphere.
Keating, G. M.↗
Direct model reference adaptive control with application to flexible robots
A modification to a direct command generator tracker-based model reference adaptive control (MRAC) system is suggested in this paper. This modification incorporates a feedforward into the reference model's output as well as the plant's output. Its purpose is to eliminate the bounded model following error present in steady state when previous MRAC systems were used. The algorithm was evaluated using the dynamics for a single-link flexible-joint arm. The results of these simulations show a response with zero steady state model following error. These results encourage further use of MRAC for various types of nonlinear plants.
Steinvorth, Rodrigo↗
Model reference adaptive control for systems with time varying model commands
Model reference adaptive control is applied to linear time invariant systems for the case of arbitrary time varying model commands. Asymptotic stability is guaranteed, provided that the output stabilized transfer matrix is strictly positive real. Only output measurements are needed. Neither perfect model following nor explicit parameter identification is required. Simulations show the scheme to be capable of guaranteeing stability when the model inputs are time varying.
Abida, L.↗
Model reference control of the NASA SCOLE problem
Model reference controllers have been developed and applied to the linearized Spacecraft Control Laboratory Experiment (SCOLE) roll beam mode equation. When a large- but finite-dimensional approximation to the partial differential equation is used, the resulting control will be finite-dimensional, but possibly not adequately representative for the actual distributed-parameter system. To date the theory for such model reference controllers has been developed; here it is applied to a 16th-order finite-dimensional representation of the flexible and rigid body modes of the SCOLE. Results of the analysis and some preliminary simulation studies are presented.
Kaufman, Howard↗
Extensions to the CIRA reference models for middle atmosphere ozone
The recent ozone reference models generated for the new COSPAR CIRA include ozone vertical structure from 25 to 90 km as a function of month and latitude based on five satellite experiments. The new model provided here extends the ozone vertical structure climatology from 20 mb (about 25 km) to 70 mb (about 18 km) based on three years of recently reprocessed AEM-2 SAGE I (sunset) data. In addition, model refinements are made at altitudes above 25 km based on the reprocessed data. Comparisons are made between the ozone reference models and nonsatellite data sets. The model extensions to lower altitudes are in excellent agreement with in situ measurements both at mid latitudes and in the tropics. Annual mean models of ozone are also provided as a function of latitude from 100 mb (about 16 km) to 0.003 mb (about 90 km).
Keating, G. M.↗
Modeling Reference Cell Performance Using Measured and Modeled Spectral Data
The performance of several silicon-based reference cells is examined under clear skies on a horizontal and two-axis tracking surface during the winter of 2022. The ratio of the calculated reference cell output to the measured reference cell output is examined. For each reference cell, when using the measured spectral data, the ratio of the estimated to measured output varies by less than +/-0.6% at the P95 level. The analysis was also done using modeled spectral values obtained from the Bird spectrl2 model. The ratio between the estimated reference cell output using the modeled spectral values to the measured reference cell output varies by +/-1.1% at the P95 level.
angle of incidence↗
An Update to the SWiFT V27 Reference Model
A revised Sandia V27 reference model is provided for use with the wind turbine analysis code, FAST, incorporating refined parameters based on blade geometry measurements and performance data collected during the 2017 wake steering campaign at the Scaled Wind Farm Technology (SWiFT) site. The chord, twist, and airfoil section shapes were measured at five span locations on the blades of wind turbine WTGb1. The V27 AeroDyn file was updated with values equal to the measured chord and twist. The measured airfoil shapes deviated over the aft half of the chord compared to the original blade model NACA profiles. Differences in trailing edge camber were converted to an equivalent trailing edge flap effect calculated with thin airfoil theory. These mod- ified airfoil polars were updated in the V27 FAST model. The tip-speed-ratio and root bending moment were measured experimentally in the wake steering campaign at SWiFT on wind turbine WTGa1. The torque constant and collective pitch of the model were tuned so that the model output tip-speed-ratio and thrust, root bending moment matched the experiment across all wind speeds in region 2 operation with minimum error.
17 WIND ENERGY↗
A Reference Model for Virtual Machine Launching Overhead
Cloud bursting is one of the key research topics in the cloud computing communities. A well designed cloud bursting module enables private clouds to automatically launch virtual machines (VMs) to public clouds when more resources are needed. One of the main challenges in developing a cloud bursting module is to decide when and where to launch a VM so that all resources are most effectively and efficiently utilized and the system performance is optimized. However, based on system operational data obtained from FermiCloud, a private cloud developed by the Fermi National Accelerator Laboratory for scientific workflows, the VM launching overhead is not a constant. It varies with physical resource utilization, such as CPU and I/O device utilizations, at the time when a VM is launched. Hence, to make judicious decisions as to when and where a VM should be launched, a VM launching overhead reference model is needed. In this paper, we first develop a VM launching overhead reference model based on operational data we have obtained on FermiCloud. Second, we apply the developed reference model on FermiCloud and compare calculated VM launching overhead values based on the model with measured overhead values on FermiCloud. Our empirical results on FermiCloud indicate that the developed reference model is accurate. We believe, with the guidance of the developed reference model, efficient resource allocation algorithms can be developed for cloud bursting process to minimize the operational cost and resource waste.
Wu, Hao↗
Provision for Guaranteed Inertial Response in Diesel-Wind Systems via Model Reference Control
Frequency performance has been a crucial issue for islanded microgrids. On one hand, most distributed energy resources (DER) are converter-interfaced and do not inherently respond to frequency variations. On the other hand, current inertia emulation approach cannot provide guaranteed response. In this paper, a model reference control based inertia emulation strategy is proposed for the diesel-wind systems. Desired inertia can be precisely emulated through the proposed strategy. A typical frequency response model with parametric inertia is set to be the reference model. A measurement at a specific location delivers the information about the disturbance acting on the diesel-wind system to the reference model. The objective is for the speed of the diesel generator to track the reference so that the desired inertial response is realized. In addition, polytopic parameter uncertainty will be considered. The control strategy is configured in different ways according to different operating points. The parameters of the reference model are scheduled to ensure adequate frequency response under a pre-defined worst case. The controller is implemented in a nonlinear three-phase diesel-wind system fed microgrid using the Simulink software platform. Lastly, the results show exact synthetic inertia is emulated and adequate frequency response is achieved.
24 POWER TRANSMISSION AND DISTRIBUTION↗
Self-Protective Inverters Against Malicious Setpoints Using Analytical Reference Models
This paper presents the concept of self-protective inverters using reference models. In the proposed method, incoming setpoints from the utility operator or third-party aggregators are inspected using analytical reference models before engaging the setpoints to the inverter’s local controller. When a malicious setpoint passes the existing security layers, a smart inverter can examine the integrity of an incoming setpoint in real-time. The efficacy of the developed method has been tested using a laboratory setup, including a three-phase 3kVA SiC-MOSFET inverter and a 12kW NHR 9410 regenerative grid emulator. Furthermore, the results verify that the developed analytical models can provide device-level protection for grid-interactive inverters by inspecting and preventing harmful setpoints from getting engaged to the local controller.
42 ENGINEERING↗
Improved reference models for middle atmosphere ozone
This paper describes the improvements introduced into the original version of ozone reference model of Keating and Young (1985, 1987) which is to be incorporated in the next COSPAR International Reference Atmosphere (CIRA). The ozone reference model will provide information on the global ozone distribution (including the ozone vertical structure as a function of month and latitude from 25 to 90 km) combining data from five recent satellite experiments: the Nimbus 7 LIMS, Nimbus 7 SBUV, AE-2 Stratospheric Aerosol Gas Experiment (SAGE), Solar Mesosphere Explorer (SME) UV Spectrometer, and SME 1.27 Micron Airglow. The improved version of the reference model uses reprocessed AE-2 SAGE data (sunset) and extends the use of SAGE data from 1981 to the 1981-1983 time period. Comparisons are presented between the results of this ozone model and various nonsatellite measurements at different levels in the middle atmosphere.
Keating, G. M.↗
An Optimal Control Modification to Model-Reference Adaptive Control for Fast Adaptation
This paper presents a method that can achieve fast adaptation for a class of model-reference adaptive control. It is well-known that standard model-reference adaptive control exhibits high-gain control behaviors when a large adaptive gain is used to achieve fast adaptation in order to reduce tracking error rapidly. High gain control creates high-frequency oscillations that can excite unmodeled dynamics and can lead to instability. The fast adaptation approach is based on the minimization of the squares of the tracking error, which is formulated as an optimal control problem. The necessary condition of optimality is used to derive an adaptive law using the gradient method. This adaptive law is shown to result in uniform boundedness of the tracking error by means of the Lyapunov s direct method. Furthermore, this adaptive law allows a large adaptive gain to be used without causing undesired high-gain control effects. The method is shown to be more robust than standard model-reference adaptive control. Simulations demonstrate the effectiveness of the proposed method.
Nguyen, Nhan T.↗
Model reference control of distributed parameter systems: Application to the SCOLE problem
The model reference control of lumped linear systems and the model reference control of the distributed parameter system (DPS) are presented with their theory and Spacecraft Control Laboratory Experiment (SCOLE) applications.
Kaufman, H.↗
An implicit adaptation algorithm for a linear model reference control system
This paper presents a stable implicit adaptation algorithm for model reference control. The constraints for stability are found using Lyapunov's second method and do not depend on perfect model following between the system and the reference model. Methods are proposed for satisfying these constraints without estimating the parameters on which the constraints depend.
Mabius, L.↗
Performance Optimizing Adaptive Control with Time-Varying Reference Model Modification
This paper presents a new adaptive control approach that involves a performance optimization objective. The control synthesis involves the design of a performance optimizing adaptive controller from a subset of control inputs. The resulting effect of the performance optimizing adaptive controller is to modify the initial reference model into a time-varying reference model which satisfies the performance optimization requirement obtained from an optimal control problem. The time-varying reference model modification is accomplished by the real-time solutions of the time-varying Riccati and Sylvester equations coupled with the least-squares parameter estimation of the sensitivities of the performance metric. The effectiveness of the proposed method is demonstrated by an application of maneuver load alleviation control for a flexible aircraft.
Adaptive Control↗
Proposed reference models for atomic oxygen in the terrestrial atmosphere
A provisional Atomic Oxygen Reference model was derived from average monthly ozone profiles and the MSIS-86 reference model atmosphere. The concentrations are presented in tabular form for the altitude range 40 to 130 km.
Llewellyn, E. J.↗