Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “PID”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS2024

Derivation of Equations of Motion and Model-based Control for 3D Rigid Body Approximation of LUVOIR

The Large UV/Optical/IR Surveyor (LUVOIR) is a conceptual space observatory under development by NASA Goddard Space Flight Center for the Astronomy and Astrophysics Decadal Survey. As with similar space telescopes, e.g., James Webb, this spacecraft will have ultra-stringent pointing stability requirements, i.e., on the order of miliarcseconds. Thus, the design of the LUVOIR attitude control system (ACS) may benefit from a model-based approach. In this document, we present an approximate model of the LUVOIR composed of two 3D rigid bodies connected by a 1-DOF rotary joint. From this model, we derive the nonlinear equations of motion, following the approach of Eric T. Stoneking [1], and linearize them about an arbitrary reference orientation. Using the subsequent state space representation, it is straightforward to compute a set of control gains (e.g., via the ”lqr” or ”place” commands in MATLAB). We conclude this memo with a comparison of our LQR approach with the existing PID slew controller designed by a former NASA intern.

William Bentz↗
NASA NTRSDate not supplied

Controls Modeling Approach for Deployment of a Large Thin Structure for Solar Sails

One of the principal challenges with solar sails is to safely deploy the large sail structures while simultaneously maintaining attitude control. This challenge includes changing moments and products of inertia along with large sail shape uncertainties as it transitions from stowed to the fully deployed shape at the end of the deployment. With these changes, the control system must manage any potential momentum buildup and keep the pointing within mission requirements. The attitude determination and control system team for Solar Cruiser, a 1600 square meter solar sail project out of Marshall Space Flight Center, approached this problem by modeling the nominal moments and products of inertia for different stages of deployment from 10% to 100% in 10% increments. At each step, the inertias were used to generate tuned PID gains, which were used as part of a nominal deployment analysis to prevent unintentional slewing and tumbling. The team created and analyzed off nominal cases, where the moments of inertia and products were changed to induce uncertainties for the control system to manage during deployment. These cases helped verify that the control system can handle off-nominal deployments as well as any uncertainties occurring during deployment of the space sail system. This paper will show this method can be successfully used for modeling solar sail deployments as part of the attitude control system.

Solar Sails↗
NASA NTRSDate not supplied

Controls Modeling Approach for Deployment of a Large Thin Structures for Solar Sails

One of the principal challenges with solar sails is to safely deploy the large sail structures while simultaneously maintaining attitude control. This challenge includes changing moments and products of inertia along with large sail shape uncertainties as it transitions from stowed to the fully deployed shape at the end of the deployment. With these changes, the control system must manage any potential momentum buildup and keep the pointing within mission requirements. The attitude determination and control system team for Solar Cruiser, a 1600 square meter solar sail project out of Marshall Space Flight Center, approached this problem by modeling the nominal moments and products of inertia for different stages of deployment from 10% to 100% in 10% increments. At each step, the inertias were used to generate tuned PID gains, which were used as part of a nominal deployment analysis to prevent unintentional slewing and tumbling. The team created and analyzed off nominal cases, where the moments of inertia and products were changed to induce uncertainties for the control system to manage during deployment. These cases helped verify that the control system can handle off-nominal deployments as well as any uncertainties occurring during deployment of the space sail system. This paper will show this method can be successfully used for modeling solar sail deployments as part of the attitude control system.

Solar Sails↗
DOE OSTI2016

Method and apparatus for controlling LCL converters using asymmetric voltage cancellation techniques

A method and apparatus for LCL resonant converter control utilizing Asymmetric Voltage Cancellation is described. The methods to determine the optimal trajectory of the control variables are discussed. Practical implementations of sensing load parameters are included. Simple PI, PID and fuzzy logic controllers are included with AVC for achieving good transient response characteristics with output current regulation.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2016

DEVELOPMENT AND TESTING OF FAULT-DIAGNOSIS ALGORITHMS FOR REACTOR PLANT SYSTEMS

Argonne National Laboratory is further developing fault diagnosis algorithms for use by the operator of a nuclear plant to aid in improved monitoring of overall plant condition and performance. The objective is better management of plant upsets through more timely, informed decisions on control actions with the ultimate goal of improved plant safety, production, and cost management. Integration of these algorithms with visual aids for operators is taking place through a collaboration under the concept of an operator advisory system. This is a software entity whose purpose is to manage and distill the enormous amount of information an operator must process to understand the plant state, particularly in off-normal situations, and how the state trajectory will unfold in time. The fault diagnosis algorithms were exhaustively tested using computer simulations of twenty different faults introduced into the chemical and volume control system (CVCS) of a pressurized water reactor (PWR). The algorithms are unique in that each new application to a facility requires providing only the piping and instrumentation diagram (PID) and no other plant-specific information; a subject-matter expert is not needed to install and maintain each instance of an application. The testing approach followed accepted procedures for verifying and validating software. It was shown that the code satisfies its functional requirement which is to accept sensor information, identify process variable trends based on this sensor information, and then to return an accurate diagnosis based on chains of rules related to these trends. The validation and verification exercise made use of GPASS, a one-dimensional systems code, for simulating CVCS operation. Plant components were failed and the code generated the resulting plant response. Parametric studies with respect to the severity of the fault, the richness of the plant sensor set, and the accuracy of sensors were performed as part of the validation exercise. The background and overview of the software will be presented to give an overview of the approach. Following, the verification and validation effort using the GPASS code for simulation of plant transients including a sensitivity study on important parameters will be presented

Fault Diagnosis Algorithm↗
DOE OSTI2016

Definition of a Robust Supervisory Control Scheme for Sodium-Cooled Fast Reactors

In this work, an innovative control approach for metal-fueled Sodium-cooled Fast Reactors is proposed. With respect to the classical approach adopted for base-load Nuclear Power Plants, an alternative control strategy for operating the reactor at different power levels by respecting the system physical constraints is presented. In order to achieve a higher operational flexibility along with ensuring that the implemented control loops do not influence the system inherent passive safety features, a dedicated supervisory control scheme for the dynamic definition of the corresponding set-points to be supplied to the PID controllers is designed. In particular, the traditional approach based on the adoption of tabulated lookup tables for the set-point definition is found not to be robust enough when failures of the implemented SISO (Single Input Single Output) actuators occur. Therefore, a feedback algorithm based on the Reference Governor approach, which allows for the optimization of reference signals according to the system operating conditions, is proposed.

Sodium-cooled Fast Reactors, Supervisory control s↗
DOE OSTI2016

The Detector Design of the Jefferson Lab EIC

The Electron-Ion Collider (EIC) is envisioned as the next-generation U.S. facility to study quarks and gluons in strongly interacting matter. The broad physics program of the EIC aims to precisely image gluons in nucleons and nuclei and to reveal the origin of the nucleon spin by colliding polarized electrons with polarized protons, polarized light ions, and heavy nuclei at high luminosity. The Jefferson Lab EIC (JLEIC) design is based on a figure-8 shaped ring-ring collider. The luminosity, exceeding 1033cm -2 s -1 in a broad range of the center-of-mass energy and maximum luminosity above 1034cm -2 s -1 , is achieved by high-rate collisions of short small-emittance low-charge bunches made possible by high-energy electron cooling of the ion beam and synchrotron radiation damping of the electron beam. The polarization of light ion species (p, d, 3He) can be easily preserved and manipulated due to the unique figure-8 shape of the collider rings. The focus of this presentation is put on the JLEIC primary detector that has been designed to support the full physics program of the EIC and to provide essentially full acceptance to all fragments produced in collisions. The detector has been fully integrated with the accelerator and extended to the forward electron and hadron regions to achieve exceptional small-angle acceptance and resolution as well as high-precision electron polarimetry and low-Q 2 tagging. The Central Detector design allows for excellent tracking up to small angles and excellent hadron PID resulting and offers a great performance, in particular for semi-inclusive and exclusive measurements. The combination of high luminosity, highly polarized lepton and ion beams, and a full acceptance, multi-purpose detector fully integrated with the accelerator will allow JLEIC a unique opportunity to make breakthroughs in the investigation of the strong interaction.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Searching for Short-Range Correlations in $^{40}AR$

The neutrino charged current (CC) cross section is critical for understanding neutrino oscillations as the flavor of a neutrino can only be determined by its CC interaction. As future generations of neutrino detectors will use argon as a target nucleus, it’s important to understand the influence that nuclear effects have on neutrino-nucleon cross sections. Short range correlations (SRCs) are an example of such an effect that are known to contribute non-trivially to the CC cross section. In MicroBooNE, a CC interaction with a correlated nucleon would lead to a 1 muon, 2 proton topology (CC2p). In order to study SRCs in MicroBooNE, It is crucial that the particle identification (PID) techniques used are efficient in identifying CC2p signals from background. Convolutional neural networks (CNN) have shown great promise in their ability to distinguish objects in an image from a noisy background. We present here our work towards the development of a CNN for CC2p event selection and identification.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

MPCPy: An Open-Source Software Platform for Model Predictive Control in Buildings

Within the last decade, needs for building control systems that reduce cost, energy, or peak demand, and that facilitate building-grid integration, district-energy system optimization, and occupant interaction, while maintaining thermal comfort and indoor air quality, have come about. Current PID and schedule-based control systems are not capable of fulfilling these needs, while Model Predictive Control (MPC) could. Despite the critical role MPC-enabled buildings can play in future energy infrastructures, widespread adoption of MPC within the building industry has yet to occur. To address barriers associated with system setup and configuration, this paper introduces an open-source software platform that emphasizes use of self-tuning adaptive models, usability by non-experts of MPC, and a flexible architecture that enables application across projects.

Blum, David↗
DOE OSTI2019

Designing and Testing a Simplified Thermal Comfort Sensor

The goal of this project was to design and test an inexpensive device to replace the need for air velocity and mean radiant temperature measurements in thermal comfort studies. The new device works by measuring heat flux across plates maintained at body temperature, mimicking the heat transfer between a person and their surroundings. Two designs were prototyped and tested. One uses thin-film heat flux sensors and one calculates heat flux from power input and surface area. Both designs consist of two plates, insulated on all but the front face, heated to 37 °C by PID controlled relays. One plate is covered in a low emissivity tape and the other in a high emissivity tape, allowing differentiation between convective and radiative heat flux. Preliminary results and literature suggest the device is feasible and responsive to environmental changes. More testing and alteration of design is necessary to fully quantify sensitivity and applicability.

Moring, Hannah↗
DOE OSTI2021

Design Study for Bio-Oil Production from Biomass Using a Dual Fluidized-Bed Reactor

To evaluate the re-design and reconfiguration of a dual-fluidized bed (DFB) gasification system into a recirculating pyrolysis reactor, Computation Fluid Dynamic (CFD) simulations of the system were conducted. The Barracuda Virtual Reactor® computational particle fluid dynamic code was used to perform simulations of the pyrolysis process. Modeling of the chemical reaction kinetics for both gas phase and solid particle phase were included. The recirculating pyrolysis reactor shown in Fig. 1a is based on a bubbling-bed biomass pyrolyzer and a riser combustor to convert the remaining char. The operational differences in the re-configuration of the DFB gasification system into a recirculating pyrolysis system for the production of bio-oil are (1) replacement of a low-surface area inert bed material with a high-surface-area bed material that has acidic properties to provide catalytic activity for the production of bio-oil with reduced oxygen content, (2) lower temperature and residence time for bio-oil production from pyrolysis, (3) replacement of the fluidization gas in the bubbling bed pyrolyzer from steam to nitrogen, and (4) the reduction of pyrolyzer freeboard volume. The bed material used for catalytic pyrolysis is Sasol 300 (300-micron dia., bulk density 0.94 kg/l, and surface area 130 m2/g) and is a theta-alumina with mild acidity. This is in comparison with previous standard bed material Carbo HSP (430-micron dia., bulk density 2.01 kg/l, and surface area 0.03 m2/g) used for gasification. For bio-oil production, pyrolysis in the bubbling bed requires temperatures in the range of 550 C in comparison with gasification temperatures near 850 C. To attain this lower temperature requires management of the energy mass balances, with control of the bed material recirculation rate between bubbling bed pyrolyzer and riser combustor, the introduction of a nitrogen purge in the pyrolyzer, and adjusting the pressure balance between the two vessels. To extract bio-oil from the pyrolysis reactor with a snorkel, two different freeboard configurations were evaluated. In Fig. 1 b the existing high freeboard configuration is shown and in Fig. 1 c the reduced freeboard design is presented. The introduction of a nitrogen purge for the high free board configuration provided the highest bio-oil production from the CFD simulations. To decrease the bed-material circulation rate, primary and secondary air on the combustor side were reduced, and the pressure on the combustor was slightly increased. A portion of the biomass and bio-oil was observed to be transported to the combustor, leading to a smaller pyrolysis yield. The control of the pyrolyzer temperature is performed by controlling the circulation rate. Good fluidization of the bubbling bed and cascade PID control are required to keep the temperature from oscillating due to large time delay experienced when changing primary and secondary air. (a) (b) (c) Figure 1. (a) Dual Fluidized Bed pyrolysis system configuration, (b) mole fraction of nonpolar biooil in high freeboard configuration, and (c) mole fraction of nonpolar bio-oil in low freeboard configuration with nitrogen purge introduced in both configurations.

BASIC BIOLOGICAL SCIENCES,BIOMASS FUELS↗
DOE OSTI2021

Model based co-simulation platform for integrated building system control and design optimization

Both steady-state and dynamic simulations have been widely used by HVAC&R industry to support product/equipment development for decades. Steady-state simulation focuses on the system mass, energy and momentum balance of an equilibrium state. It is based on high-fidelity components models, and thus is suitable for system and component design optimization. Dynamic simulation studies the system transient response and is generally used for controls development and verification. It usually does not require rigorous component models of high accuracy because 1) the commonly used PID control is feedback control whose control performance evaluation doesn’t require high fidelity system/plant model; 2) high-fidelity dynamic model significantly increases the number of equations and variables and creates tremendous challenge for math solver. For supervisory control, transactive control or optimization of an integrated building system, the HVAC&R equipment is often one of the sub-components to be controlled. High-fidelity equipment models are required for accurately evaluating control strategies. In addition, building equipment manufacturers have developed a lot of high-fidelity steady-state equipment/component models per their expertise. Thus, a platform that can integrate OEM high-fidelity steady-state model with dynamic building simulation and/or electric power system & grid simulation to support the development and verification of supervisory control for integrated building systems is necessary. In this study, ORNL’s heat pump design tool (HPDM) is utilized to develop a co-simulation platform for supervisory control and optimization in integrated building systems. It is based on a model that integrates high-fidelity steady-state simulation equipment models with dynamic building simulation. A practical case of using the proposed co-simulation platform to develop and evaluate the supervisory control and optimization is presented and discussed.

Sun, Jian↗
DOE OSTI2021

Controlling AM spatter and conduction

An intelligent feed forward model to control additive manufacturing (AM) laser powder bed fusion process and reduce spattering whereby defects are eliminated by controlling the laser power and reducing spattering through a computer model. This application describes using a proportional integral derivative (PID) controller to create a power map that reduces spattering.

Khairallah, Saad A.↗
DOE OSTI2013

Forward Drift Chamber for the GlueX experiment

The GlueX experiment will search for exotic mesons produced by 9 GeV linearly polarized photon beam from the 12 GeV CEBAF machine. A hermetic solenoid-based detector system that includes tracking and calorimetry is in the final construction phase. The Forward Drift Chamber consists of 24 circular planar drift chambers of 1 m diameter. Additional cathode strip information is required to achieve efficient pattern recognition in forward direction, resulting in 12,000 readout channels in total. Description and results from the tests of the completed detector will be presented. Challenges related to the specific features of the detector will be discussed. A small modification of the standard geometry allowed us to study the possibility for PID by cluster counting and investigate some gas properties based on single electron detection.

Pentchev, Lubomir↗
DOE OSTI2019

Development of a Semi-autonomous Miniature Rover for Inspection of Double Shell Tank Floors - 19575

Leaks in the primary liner of double-shell tank (DST) 241-AY-102 at Hanford have prompted the need for the development of inspection tools that are able to access confined spaces around and underneath the tanks. Last year, Florida International University (FIU) has continued to improve inspection tools that were developed in the previous years, to ensure that the resultant tools are able to overcome the challenges posed by the DSTs. Experimental testing conducted last year at the full-scale sectional mock-up of the DST's refractory slots revealed some shortcomings of the miniature rover, particularly in traversing over weld seams of different heights. The weld seams are the results of welded steel plate-joints for the DST. It was advised by the site engineers that the weld seams height could range from 6.35 mm - 9.525 mm (1/4 to 3/8 inches), and with 12.7 mm (1/2 inches) width. As the rover traverses over a weld seam, the gap between the rover's magnets and tank surface increases, causing the adhesive force to drop. The rover loses its surface contact if this adhesive force drops below its weight, jeopardizing the inspection tasks. In this paper, we present the numerical studies to calculate the minimum magnetic force required for the miniature rover to traverse over weld seams with different heights and the corresponding modifications to the rover design. Initial bench scale tests were conducted using a steel bar with 5 welds of varying heights. The testing validated the results from the simulation studies and established the rover's capability in traversing weld seams. Another challenge for the miniature rover is the use of a joystick or keypad for manual control. Utilizing these controls will likely be difficult for the operators due to the tight channels underneath the tank. Having a semi-autonomous navigational capability would alleviate the complexity of the inspection tasks and allow the operator to focus on the channel inspection. The goal is to implement lane-keeping capability, akin to that of a driverless car, for the inspection tool, so that it will maintain its relative position with respect to the wall of the channels. Am image processing pipeline has been developed using both the Robot Operating System (ROS) and OpenCV to process the image stream coming from the onboard camera, for the purpose of lane identification. Additionally, a PID controller has been implemented to navigate the miniature rover along the central location of the detected lane, while allowing the operator to control the tool's forward and backward motion. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Implementation of new PRODIAG algorithm and simulation-based acceptance test - 219

This paper presents the improvement of an automated-reasoning computer program for nuclear power plant diagnosis, namely PRODIAG. PRODIAG, first developed at the Argonne National Laboratory, uses confluence-based reasoning to perform fault diagnosis in engineering systems that can be described by the conservation laws for mass, energy, and momentum. Therefore, unlike other plant configuration-dependent rule-based diagnosis algorithms, the code is generally applicable to a wide variety of plant configurations by simply replacing the plant instrumentation diagram (PID) database. The need for improvement was raised when the original PRODIAG failed to provide the requisite degree of extensibility and maintainability for new applications. These shortcomings have been addressed through a new code architecture that uses an objected-oriented logic-programming language in place of the original Prolog language and uses an open-source automated reasoning engine in place of the original hardwired rule-evaluation sequence. This paper presents the architecture and implementation details of the code transition. Verification and validation studies were performed for the new PRODIAG, which involved re-running the distinct fault cases defined at the time the code was originally developed. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2023

Modelling Nuclear Thermal Propulsion Reactor Expander Cycle Startup Transients

As the interest in nuclear thermal propulsion grows, the need for high fidelity and comprehensive models of the system increases. An expander cycle model was developed using RELAP-7 for the thermal-hydraulic performance and Griffin to provide the power level using a point kinetics approximation, for a reference NTP system. The tank and pump are approximated using boundary conditions. Flow is split between the moderator cooling channels flow path and the regenerative cooling/reflector cooling channels flow path. The flow recombines before entering the turbine and the fuel cooling channels. The turbine pressure ratio is maintained at 1.44 using a PID controller. A startup transient was simulated and shows the capability of the model to run from low temperature and pressures to nominal conditions.

33 ADVANCED PROPULSION SYSTEMS↗