#Guidance Navigation and Control

Channel - #Guidance Navigation and Control

12/4/2024 1:36:46 AM

Channel Videos

An Overview of Spacecraft Attitude Determination and Estimation

This webcast will provide a general overview of attitude determination estimation. First, a review of attitude kinematics, in particular quaternions, is shown. Then, a solution to the point-by-point batch least squares problem, known as Wahba’s problem, is given. The attitude covariance is then derived and its relationship to maximum likelihood is shown. Next, an attitude Kalman filter-based estimator using attitude and gyro measurements coupled with quaternion kinematics is derived. Examples from practical scenarios and real missions are shown.

John Crassidis

1/16/2013 7:00:00 PM

Applying GN&C Solutions to the Problem of Asteroid Interception for Planetary Defense

The impact consequences of Near Earth objects (NEO) require proactive measures to eliminate or reduce them when lead times are too short for effective deep space Deflection/destruction. To expand mitigation beyond deep space, ground-based pre-built interceptors launched minutes before atmospheric entry can respond to detection times from minutes to months. The disruption of a small NEO prior to atmospheric entry could potentially eliminate or reduce damage to the ground by dispersing its kinetic energy over a wider area. The Guidance and Control Subdivision at The Aerospace Corporation has applied interceptor techniques to engage an incoming NEO at high altitude minutes before atmospheric entry. Objective is to disrupt the object and deposit its kinetic energy at a higher altitude and disperse it over a wider footprint on the ground. Monte Carlo analysis duplicated statistical properties of real NEOs on NASA’s database. Interceptor requirements were linked with flight time and altitude of intercept. Preliminary results show that Exoatmospheric intercept altitudes are attainable even when detection and launch occur minutes before impact. Local, regional or national protection requirements determine the number of systems and response time. Terminal guidance and disruption and debris reentry analysis were identified key areas of future work.

Nahum Melamed

3/1/2019 8:00:00 PM

Autonomous Deep Space Navigation

Discipline: Guidance, Navigation, & Control Webcast Air Date: 09/30/2015 For over 40 years, nations have sent spacecraft to visit other natural bodies in the Solar System, with mission profiles including high speed flybys, rendezvous and orbit, and landings. For the vast majority of these missions, navigation is performed on the ground using standard radiometric tracking data and, when required, onboard optical data (images taken by the spacecraft camera of nearby target bodies). This combination has worked well and resulted in remarkably accurate navigation over the years. Despite its success, one inherent drawback in ground-based navigation are the delays caused by the round-trip light-time and the time needed to process the data once it gets to the ground. As a result, the latest and best navigation information is not used to execute the current event with a resulting net loss of fuel, science data, or both. To overcome this limitation, an onboard autonomous navigation system, called AutoNav, was developed. Since GPS is not available in deep space, the system uses passive optical data and is thus entirely self-contained. This not only eliminates the light-time delay but also circumvents the human-related delays for performing the navigation functions, thus reducing the turnaround time to minutes, or even seconds, for reacting to late-breaking navigation information. This capability can enable certain classes of missions and greatly enhance science return on others. In this webcast, the details of AutoNav are presented, with a discussion of the basics of passive optical data and descriptions of the functions performed by AutoNav. Past uses of AutoNav on the Deep Space 1, Stardust, and Deep Impact missions are also shown, along with some thoughts about future directions.

Neil Dennehy

10/16/2015 6:00:00 PM

Autonomous Spacecraft Navigation Using Above-the-Constellation GPS Signals

Discipline: Guidance, Navigation, and Control Webcast Air Date: 12/09/2015 For more than a decade, engineers at NASA Goddard have been working on multiple fronts to advance high-altitude GPS navigation. This application poses challenges, because receivers operating above the GPS constellation are subject to reduced signal strength and availability. In this webcast, I will give an overview of past and ongoing work in this area including the development of specialized GPS receivers and navigation software, on-orbit demonstrations and operations, including the record-setting Magnetospheric Multiscale mission, a GPS transmit antenna characterization effort, and a policy effort to define and protect the "GPS Space Service Volume".

Dr. Luke Winternitz

12/9/2015 7:00:00 PM

Electric Propulsion Microthrusters for Spacecraft Precision Pointing and Attitude Control

Abstract: This talk will focus on the different applications for precision microthrusters on spacecraft position and attitude control, including the flight experience of ST7 and some recent results of performance studies looking large-scale observatories. Precision microthrusters have been operated successfully in flight, providing drag-free and precision control for spacecraft that can be used for future applications such as gravity wave and exoplanet observatories. The Space Technology 7 Disturbance Reduction System (ST7-DRS) technology demonstration payload included eight Busek Colloid Micro-Newton Thrusters (CMNTs) as part of the Laser Interferometer Space Antenna (LISA) Pathfinder mission that launched in December of 2015, which also included European cold gas microthrusters. The CMNTs provided full attitude and precision drag-free control of the spacecraft with 10 nm/√Hz stability along the most sensitive axis during commissioning, nominal, and extended mission phases through April of 2017. Performance requirements (≤0.1 µN/√Hz) were met and models were validated based on on-orbit measurements of test mass motion and actuation during the 60-day nominal and 30-day extended missions. In 2018, the European Space Agency (ESA) selected LISA to be the agency’s next “large-class” mission, currently in Phase A, with a launch scheduled for 2034 and a 12.5-year duration. NASA is considering a significant contribution of hardware to the ESA-led mission, potentially including colloid microthrusters. In preparation, NASA is developing five technologies to TRL 5 and 6, including the colloid microthrusters, to be ready for infusion into LISA. The Habitable Exoplanet (HabEx) observatory mission concept also might require precision microthrusters for attitude control, replacing reaction wheels with worse pointing performance. In this case, using colloid microthrusters have been shown to meet the tight pointing requirements necessary to image Earth-like exoplanets around nearby stars. Future Earth-orbiting gravity-measurement missions, similar to GRACE, are also considering atmospheric drag-free operation to improve resolution.

Dr. John Ziemer

2/1/2021 7:00:00 PM

Fundamentals of Adaptive Control

Prerequisites: • Basic knowledge of concepts of linear vs. nonlinear systems and their stability. • Conversant with the concepts of uncertainty, model based design (i.e. performance specification within state-space system context), robust optimal control. The field of adaptive control is as diverse as the potential applications. There are a myriad of methodologies but only some are appropriate for application to flight control. This short lecture will touch on history of adaptive control in flight, present on overview of methods that have been employed in flight over the past 10 years with illustrative examples, and discuss advantages and limitations of the methodologies. Furthermore, a recent flight test example will be presented briefly. In conclusion, current open problems and future directions will be discussed.

Irene Gregory

11/28/2012 7:00:00 PM

Fundamentals of Aircraft Engine Control

The fundamental control problem for turbomachinery based aircraft engines is to provide the right amount of fuel needed for the engine to produce a desired power (or thrust), based on the pilot's power request through a throttle (or a power lever), and maintain the engine power at the desired level in the presence of air flow disturbance and changes in flight conditions. In-flight engine thrust measurements are not possible. So some other measurable parameters which are good indicators of thrust, such as engine shaft rotational speed (N) or engine pressure ratio (EPR) are regulated by the engine control. An aircraft engine is designed to operate in a wide operating envelope in terms of altitude and speed variations. To a control engineer, these challenges are represented on a fuel flow (Wf) versus engine shaft speed (N) graph, or a fuel ratio unit (Wf/P3, where P3 is the compressor exit static pressure) versus speed graph. The control design challenge is then to be able to transition from one operating point to another while staying within the safe operational limits represented by the max. and min. fuel flow limits as well as the structural limits of the various engine components. The max. flow limit prevents the engine from over-temperature while the min. flow limit prevents the engine from flame-out. Other operational safety limits that are important are surge/stall avoidance and maximum shaft rotational speed. This lecture will cover the basic principles behind modeling the engine system for control design and how the various safety and operational limits are implemented in the engine control to provide safe and reliable operation over the flight envelope.

Dr. Sanjay Garg

11/16/2011 7:00:00 PM

Fundamentals of Aircraft Flight Control

Discipline: Guidance, Navigation, and Control Webcast Air Date: 10/17/2012 Prerequisites: Understands Elementary Laplace Transforms (solutions to differential equations) Understands the root locus classical method. (the starting point of this class) This is a linear methods design class This 50 minute "short course" will hit the major control design issues and what to beware of in the "design process". In a linear design world the actuator rates and limits are ignored, along with time delays, and this can bring down an otherwise "good design method". This class will hopefully show you ways to design a robust control design method with some of the "real world" issues involved. The control method will be the Linear Quadratic Tracker design technique, applied to the X-38 vehicle with matlab scripts included. The scripts will be provided for self-study purposes in the appendix. Not covered: Software and hardware System redundancy Verification and validation testing Digital control design

John Burken

10/17/2012 6:00:00 PM

Fundamentals of Deep Space Mission Design

Guidance, Navigation and Control Webcast Series

Dennis Byrnes

3/21/2012 6:00:00 PM

Fundamentals of Image Processing for Terrain Relative Navigation (TRN)

Discipline: Guidance, Navigation and Control (SLaMS Webcast Series) Presented via Webcast on April 23, 2014 Current robotic planetary landers do not identify landmarks for navigation or detect landing hazards for safe landing. Typically they just measure altitude and velocity and land in a relatively large landing ellipse that is free from hazards. Since the best science is usually located near terrain relief that exposes material from of different ages, this “blind” landing approach limits science return. For example, the Mars Science Laboratory Curiosity rover landed in with a landing ellipse tens of kilometers wide in a flat region of Gale crater. Curiosity is currently driving to Mount Sharp, which is the primary science destination. There are two complimentary technologies being developed to enable access to more extreme terrain during landing: Terrain Relative Navigation (TRN) for accurate position estimation and Hazard Detection for avoiding small, unknown hazards. During TRN the lander automatically recognizes landmarks and computes a map relative position, which can be used in two different ways. First, if there is enough fuel, the lander is guided to a pin-point landing (within 100m of the target). If the vehicle is limited on fuel, then the landing ellipse is populated with safe landing sites and the lander is guided to the safest reachable site. This multi-point safe landing strategy enables selection of landing ellipses with large distributed hazards. Both applications improve science return by placing the lander closer to terrain relief. This presentation will describe the image processing building blocks for development of a TRN system for planetary landing including: image warping, feature selection and image correlation. It will then describe the Lander Vision System (LVS) that integrates these components into a real-time image-based terrain relative navigation system and show results from a recent field test of the LVS. The presentation will conclude by showing how the same image processing techniques can be applied to lidar data to enable TRN under any lighting conditions.

Andrew Johnson

7/3/2014 6:00:00 PM

Fundamentals of Kalman Filtering and Estimation

Kalman Filtering and Least Squares Estimation have been at the heart of the GNC system design within the US Space Program since it's inception. Yet, there is a great deal of mystique surrounding the subject because it requires a modicum of familiarity with linear analysis, nonlinear analysis, optimization, and statistics. This goal of this seminar is to present a gentle introduction to Kalman Filtering and estimation to those who aren't familiar with the topic, or who have viewed it with fear and trepidation. Beginning with linear systems, the basic concepts will be introduced, and several examples will serve to flesh out the concepts. There will be an emphasis on practical implications and implementations of these concepts, with an eye toward helping develop intuition and demystifying the field.

Chris D'Souza

3/20/2013 6:00:00 PM

Fundamentals of Launch Vehicle Flight Control System Design

This presentation is intended to be an introductory overview of launch vehicle guidance, navigation and control for ascent. We will look at the big picture of how these three disciplines are interconnected in a launch vehicle design, and we will look at the flow of the design process. We will see how GN&C design relies on and influences many project stakeholders. Then we will look at each of the three disciplines, individually. Some key issues and design implementations will be pointed out in each of the three disciplines. Recent experiences from Ares I design will be used to illustrate some of the concepts.

John Rakoczy

5/16/2012 6:00:00 PM

Fundamentals of Libration Point Mission Design

Discipline: Guidance, Navigation & Control Webcast Air Date: October 19, 2016 The vicinity near the Earth-Moon libration points has recently emerged as a potential location to support future crewed and robotic missions as part of a resilient and evolving space infrastructure. Beyond cislunar space, successful missions to the vicinity of the Sun-Earth/Moon libration points have also been accomplished and other Sun-planet and planet-moon options are being explored. Such mission scenarios offer unprecedented opportunities but involve complex and competing requirements. The mathematical foundations and dynamical structures in this multi-body environment are exploited for trajectory design in planning missions of this type and a new generation of strategies and analysis tools are evolving to enable the practical implementation of the complex new concepts. In particular, the existence of periodic orbits throughout a libration point region serves as a framework and the connections between various families allows movement throughout the region. This webcast will include a discussion of the astrodynamics basics to design such trajectories and some techniques to leverage the dynamical structures.

Dr. Kathleen Howell

11/4/2016 3:00:00 PM

Fundamentals of Libration Point Mission Design - Applications

Discipline: Guidance, Navigation & Control Webcast Air Date: January 18, 2017 With the fundamentals of libration point mission design essentially understood, application of these multi-body environment basics is being pursued through research and the incorporation of these techniques into the operational mission design process. The vicinity near and through libration points has been exploited by many missions both as the desired science location as well as gateways to attain unique science orbits. Such mission scenarios offer exceptional opportunities but involve complex and competing requirements. The libration point orbit mathematical foundations and dynamical structures are evolving to enable the real-world applications. For example, the construction of periodic orbits and their stable and unstable manifolds are routinely generated as initial conditions for final trajectory optimization in operational mission design tools. This webcast includes a discussion of the basics of libration point astrodynamics and the application of these mathematical constructs to design such trajectories.

David Folta

1/30/2017 7:00:00 PM

Fundamentals of Linear Stability

Webcast Live: 9/17/2014 2:00 PM EDT Typically the stability requirements for a control system are given in terms of gain margin and phase margin. These stability margins represent the tolerance of the control loop to perturbations in loop gain and phase delay. This webcast will review the stability analyses of linear continuous time invariant dynamical systems as commonly presented in a first-year college course covering Single Input Single Output (SISO) control systems. A more compact single stability margin will be introduced in this webcast that specifies the stability at all frequencies and in particular in the region between the gain and phase cross-over frequencies. The equivalence between this single stability margin metric and the more commonly used gain and phase margins will be established. The inverse relationship between this single stability margin and the Sensitivity Transfer Function for low frequency disturbance rejection is also highlighted in this webcast. Discipline: Guidance Navigation & Control

Ken Lebsock

10/2/2014 6:00:00 PM

Fundamentals of Piloted Spacecraft Handling Qualities

Discipline: Guidance, Navigation, and Control Handling qualities are those characteristics of a flight vehicle that govern the ease and precision with which a pilot can perform a flying task. NASA requirements for human-rated spacecraft include a capability for manual control of attitude and flight path, as well as satisfactory handling qualities during manual piloting. This seminar presents an introduction to handling qualities and covers highlights of some recent spacecraft handling qualities experiments conducted in the world's largest motion-travel flight simulator located at NASA Ames Research Center. The goal of these research studies was to initiate the development of a knowledge base to guide the design of flight control systems and cockpit displays for the next generation of piloted spacecraft. Six experiments were conducted over a time span of three years, covering a diverse set of piloting tasks: powered-descent lunar landing, docking with the International Space Station, and atmospheric entry of a capsule spacecraft. Four Apollo astronauts, 29 Space Shuttle astronauts, and five NASA test pilots participated in these experiments and provided evaluations of spacecraft handling qualities.

Dr. Karl Bilimoria

1/18/2012 7:00:00 PM

Fundamentals of Spacecraft Attitude Control

Spacecraft attitude control systems are onboard systems that autonomously orient a spacecraft relative to a target reference frame. Spacecraft operate in a regime of very little disturbance torque as compared to atmospheric vehicles, and we therefore have greater expectations for their accuracy and stability. An understanding of the disturbance environments in various flight regimes is critical to design choices. Means of attitude stabilization run the gamut from passive to active methods and from spin-stabilized to zero-momentum three-axis stabilized systems. Control methods derive from the same body of control theory as other modern systems, with control bandwidths often in a range of much less than 1 Hz to avoid control-structure interaction. Attitude dynamics are inherently nonlinear but only occasionally require nonlinear control techniques, as the typically slow rate of attitude change usually allows linear design techniques to work well. Related topics that will be briefly addressed include attitude estimation techniques, attitude ground systems, and jitter (attitude motion outside the control bandwidth).

Scott Starin

7/18/2012 6:00:00 PM

Fundamentals of Spacecraft Control-Structure Interaction

Discipline: Guidance, Navigation & Control Webcast Air Date: March 15, 2017 Flexibility and nonlinearities in a spacecraft or launch vehicle’s structure can interact with control loops, potentially impacting pointing performance or creating instabilities or limit cycles. These effects can cause mission degradation or even loss of vehicle. In order to successfully assess the interplay between controls and structures, a cross-discipline design and analysis process must be established and followed throughout the development phase of a program. This presentation provides an introduction to the fundamentals of control-structure interaction, providing an overview of the design process, some examples and rules of thumb, and references for further study. Topics addressed include structural model accuracy and validation, structural damping, model reduction, model uncertainty, and common control design and analysis techniques.

Dr. Davin Swanson

3/31/2017 6:00:00 PM

Fundamentals of Vision Based Navigation

This webcast will introduce participants to the fundamental ideas behind spacecraft optical navigation. We will begin by discussing camera projection and how pixel coordinates in an image may be related to line-of-sight directions. With this in mind, we will explore some common optical navigation measurement techniques including centroiding, star-limb measurements, and landmark tracking. These techniques have found widespread use in exploration missions to the Moon, other planets, comets, and asteroids. Beyond this, optical navigation methods may also be used for relative navigation in support of rendezvous, proximity operations, and docking (RPOD) activities. We will briefly discuss some techniques used for these applications, such as Natural Feature Image Recognition (NFIR) algorithms.

Dr. John Christian

2/26/2014 7:00:00 PM

Implementation Challenges for Multivariable Control: What You Did Not Learn in School

Discipline: Guidance, Navigation and Control Presented via Webcast on 6-18-2014 Multivariable control allows controller designs that can provide decoupled command tracking and robust performance in the presence of modeling uncertainties. Although the last three decades have seen extensive development of multivariable control theory and example applications to complex systems in software/hardware simulations, there are no “production” flying systems – aircraft or spacecraft, that use multivariable control. This is because of the tremendous challenges associated with implementation of such multivariable control designs. Unfortunately, the curriculum in schools does not provide sufficient time to be able to provide an exposure to the students in such implementation challenges. The objective of this presentation is to share the lessons learned by a practitioner of multivariable control in the process of applying some of the modern control theory to the Integrated Flight Propulsion Control (IFPC) design for an Advanced Short Take-Off Vertical Landing (STOVL) aircraft simulation. The presentation focuses on the challenges and barriers of using multivariable control designs in real flight systems, and presents tools and techniques for overcoming some of the barriers with illustrative examples from the STOVL IFPC design study. Discipline: Guidance Navigation & Control

Dr. Sanjay Garg

7/25/2014 6:00:00 PM

Moving Cross Town or Cross the Solar System, Putting the Pieces Together - Launch Vehicle Mission Flow and Model Based Systems Engineering (MBSE)

Are you curious about how we would assemble a complex exploration class mission architecture in space or what it takes just to get a lot pieces integrated onto a LV and flown in the first place? Join us for a webcast to hear Neil Dennehy describe and discuss the challenges of Rendezvous and Capture and Jessica Knizhnik describe on-going work to digitally capture sounding rocket mission flows using Model Based Systems Engineering.

Jon Holladay

10/21/2016 3:00:00 PM

NASA Space Situational Awareness (SSA) Overview

SSA is defined as "the requisite current and predictive knowledge of the space environment and the operational environment upon which space operations depend". SSA provides knowledge and understanding of threats posed to space systems by adversaries and the environment and is essential in developing and employing space asset protection measures. NASA is both a provider and consumer of SSA data. This talk will describe the Agency's role in SSA, with particular emphasis on the robotic conjunction assessment effort. SSA policy, procedures, interfaces, and goals will be discussed.

Lauri Kraft Newman

7/26/2012 6:00:00 PM

Robust Stability: From Disk Margins to Neural Network Analysis

Recorded June 24, 2020 This talk will provide a tutorial introduction to disk margins. These are robust stability measures that account for simultaneous gain and phase perturbations in a feedback system. This provides a generalization of classical (gain-only and phase-only) stability margins. The talk will motivate the use of disk margins and provide several examples including applications to multiple-input, multiple-output control systems. The talk will conclude with some recent extensions of this basic robustness analysis framework. It will be shown that typical robust control methods can be used to assess stability and robustness of feedback loops that use neural networks.

Dr. Peter Seiler

8/11/2020 6:00:00 PM

STS/ISS On-Orbit Flight Control: A Historical Perspective or Some Funny Things Happened While Assembling the Space Station

This aired on February 26th, 2020 The assembly of the International Space Station was a very complex flight control and integration challenge. This presentation discusses some of those challenges, along with some things that happened along the way that weren't expected.

Dr. Bob Hall

6/4/2020 6:00:00 PM

The Evolution of Guidance, Navigation, and Control in Mars Entry, Descent, and Landing

From Viking in the 70's to MSL/Curiosity in the present, Guidance, Navigation, and Control for Mars Entry, Descent, and Landing (EDL), has varied dramatically in form and function, as it had to adapt to different types of landing architectures in response to ever changing mission requirements. This presentation will describe the history of EDL GN&C as represented by its functional and performance requirements, and the architectures and implementations needed to satisfy them, starting with the unguided Viking legged-landers, continuing with the Mars Exploration Rover airbag-landers, and concluding with Curiosity's fully guided Entry and SkyCrane-lander.

Miguel San Martin

5/15/2013 6:00:00 PM

Time and Time Again: Basic Concepts

Aired November 15, 2017 "Time can be can be the most confusing aspect of astronomy." — Laurence G. Taft, Computational Spherical Astronomy Time is also confusing for those trying to use software from the various software sets in use at JPL if they are pre-SPICE/Monte. The time system in use can be: not known by the users, assumed to be understood, regarded as irrelevant, or use date dependent configurations that are not in sync. This talk was first given in January of 2012. However, time marches on and change comes with it. New people are in the section, people change jobs, leap seconds occur. This talk will go over: the various time systems in common use here, how they are used, and which one(s) to use if you have a choice in the matter.

Dr. William Taber

1/11/2018 7:00:00 PM

X-15 Flight 3-65-97 Accident Analysis: A Fresh Look at the Role of the MH-96 "Self-Adaptive" Flight Control System

Discipline: Guidance, Navigation and Control Presented via Webcast on May 28, 2014 Over its ten year lifespan and 199 flights, the X-15 program was remarkably successful in developing and operating the first manned hypersonic research platform. However, the program suffered a fatal accident in November 1967 when X-15-3, the only aircraft outfitted with advanced pilot displays, an adaptive flight control system, and an advanced reaction control system was lost after entering a spin at an altitude of 230,000 feet and a velocity near Mach 5. The pilot, USAF Maj. Michael J. Adams, was killed when the aircraft broke up at 62,000 feet near Cuddeback Lake, CA. In an effort to reduce risk to emerging aerospace vehicle concepts, a comprehensive analysis has been undertaken to fully understand the causes and evolution of the accident in light of fifty years of flight control and human factors experience. Attention is focused on both the technical as well as the programmatic and cultural factors that affected the outcome in this incredibly complex accident. New findings have emerged that change our understanding of the roles of the adaptive control system, the pilot, and ground control in the incident.

Jeb Orr

7/30/2014 6:00:00 PM

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