Browse Topic: Flight guidance systems
This paper presents enhancements to the supervisory controller developed for the National Research Council Canada's Bell 412 autonomous helicopter. Building on a Discrete Event System Specification (DEVS)-based framework, the updated Supervisor introduces two new operational modes-Knobs Mode and Sticks Mode-and a structured approach for managing transitions between them and the existing modes. Drawing inspiration from NASA's Flight Guidance System philosophy, the proposed design emphasizes consistency, scalability, and flexibility in handling multiple autonomy modes. Implementation results demonstrate the effectiveness of the updated architecture in supporting future expansion of autonomous mission operations in complex and dynamic environments.
Northrop Grumman Woodland Hills, CA 224-200-7539
This document recommends criteria and requirements for a flight management system (FMS) for transport aircraft. The FMS shall provide the functions of lateral navigation, vertical navigation, and performance management and may include time of arrival control. The FMS design shall take human factors considerations into account to produce a fault tolerant system.
The objective of the joint National Research Council of Canada (NRC) and The Boeing Company Technology Development Program (TDP) entitled 'Canadian Vertical Lift Autonomy Demonstration' (CVLAD) is to evaluate automated and supervised autonomous flight systems on NRC Bell 412 Advanced Systems Research Aircraft (ASRA) and Royal Canadian Air Force Boeing CH-147F Chinook demonstrators. Boeing technologies such as Degraded Visual Environment Pilotage System and Advanced Vehicle Management System form the foundation of an autonomy solution that aims to satisfy Royal Canadian Air Force, US Army, and other Armed Service branch end-use objectives for force multiplication, tactical advantage, pilot assistance, reduced crew operations, and enhanced fleet productivity. The Boeing Company engaged NRC under a Cooperative Research Agreement since 2016 as part of a number of strategies to upgrade Medium-Heavy Lift H-47 Chinook capabilities prior to long-term aircraft replacement in the 2030 to 2060 timeframe. A recent achievement of the CVLAD TDP by its Boeing Phantom Works, Boeing Chinook Program, Aurora Flight Sciences, and NRC Flight Research Laboratory team was the development of Automated Flight Guidance methods addressing system safety and performance. Design and evaluation activities occurred in Boeing Software-/Hardware in-loop facilities as well as on the NRC Bell 412 ASRA. The CVLAD team is using a blend of traditional Systems Engineering 'V-Shaped' Life Cycle Model, System of Systems, and Model-Based processes to develop a cyber-physical system that aims to meet end-user concept of operations and requirements. Significant benefits of virtual development tools such as component-vehicle digital twins and surrogate inflight simulation facilities are achieved as they promote effective collaboration, efficient design, and relevant verification/validation methodologies. Business models can be made more robust by phasing the introduction of technology where effective automation provides users with near-term benefits, while providing a foundation for safe, reliable, and trusted autonomous capabilities for long-term production.
Successful human intervention will be central to any emerging autonomous aerial transport platform, such as personal aerial vehicles (PAV), for the safe conduct of flight. This paper proposes a concept to compensate a partial failure of the autonomous flight guidance by handing over control of the aircraft to a passenger and analyzes the associated human factors. First, a novel waypoint guidance law is designed that generates the desired roll commands for navigation to a designated safe landing spot. Second, two novel guidance display concepts are developed, one for the primary flight display (PFD), and another for the helmet mounted display (HMD), which indicate the desired roll commanded by the guidance law. Third, the guidance law and display concepts are integrated into a high-fidelity, wide field-of-view flight simulation environment and a static mock-up of a conventional helicopter cockpit. Humanin-the-loop experiments were performed with test subjects to analyze the effectiveness of the guidance law and display concepts, and to evaluate piloting performance by non-professional pilots. Various mission task elements were analyzed in these experiments and, in order to intensify workload, a disturbance was included together with a guidance law for commanded roll of PAV. Navigation performance, test subjects' ratings and workload are measured by a combination of objective and subjective analyses. Results indicate that all test subjects were able to reach a close vicinity of the landing spot. Furthermore, the HMD concept shows a lower workload with equal or better navigation performance when compared to the PFD concept.
There is emerging demand for multi-ship sensor-based 3D world modeling (3DWM) for autonomy/cognitive decision aiding avionics applications. In these systems, multiple ships collect and transmit perception sensor data that is fused into a common 3DWM, which is then used by other platforms for flight guidance in that environment. This paper illustrates key design considerations for these systems by exploring the fundamental scenario of leader-follower. This paper will detail the design trade space for the leader-follower scenario, focusing on 3DWM database representation/processing and data transmission. To demonstrate the feasibility of a baseline design approach on modern computing hardware, results will be presented from an experimental evaluation of a proof-of-concept system.
Landing helicopters in Degraded Visual Environments (DVE) is one of the most challenging maneuvers pilots perform. The U.S. Army Combat Capabilities Development Command, Aviation & Missile Center, Aviation Development Directorate has been working to develop flight guidance and sensor systems to provide the pilot with guidance and pilot cueing to land a helicopter, hover, and take off in DVE. During flight testing of the Brown Out Symbology System (BOSS) on an EH-60L Black Hawk, pilots reported very high workload requiring full concentration on the displays during approaches to landing in brownout. In order to reduce pilot workload, an approach to provide the pilot with a collective tactile cue based on coupling of the output of the approach to landing algorithms to the EH-60L collective trim servo was developed and flight tested. Flight testing of the coupled collective system demonstrated a reduction in pilot workload and increase in the pilot's situational awareness during landing in brownout. To further reduce pilot workload, the pilot cyclic and pedals have been coupled with the guidance symbology to allow for fully coupled landings. Details of the system are provided along with the initial results of flight testing of the system at Felker Army Airfield, Ft. Eustis VA.
Landing helicopters in Degraded Visual Environments (DVE) is one of the most challenging maneuvers pilots perform. The US Army Aviation and Missile Research, Development and Engineering Center (AMRDEC) has been working to develop flight guidance and sensor systems to provide the pilot with guidance and pilot displays to land a helicopter, hover, and take off in DVE. During flight testing of the Brown Out Symbology System (BOSS) on an EH-60L, pilots reported very high workload requiring full concentration on the displays during approaches to landing in brownout. In order to reduce pilot workload, an approach to provide the pilot with a collective tactile cue based on coupling of the output of the symbology display algorithms to the EH-60L collective trim servo has been developed and flight tested. Details of the system are provided along with the results of flight testing conducted at the Yuma Proving Grounds comparing workload from approaches to landing in brownout with and without the collective coupling engaged.
DLR and ONERA have a long-term cooperation on the evaluation of technologies for "easy flying" helicopters. Active inceptors are one of these promising technologies. They are expected to improve flight safety, provide workload reductions, and demonstrate operational benefits. During the last year, flight tests at the DLR have effectively shown how tactile cueing with active inceptors can reduce pilot workload and improve mission effectiveness [1]. Among the developed functions were load limitation and flight guidance functions. At ONERA, since year 2000 several projects were carried out in the field of helicopter Flight Envelope Protection. The Vortex Ring State (VRS) regime exploration was one of the successful flight test programs during which this dangerous regime was deeply analyzed. DLR and ONERA are now sharing their experience through self funded projects and gathering their complementary activities in the area of flight envelope protection (FEP). In the framework of this Research Field a specific joint-team is in charge of the design and the evaluation of several FEP functions through active side-sticks. The VRS avoidance was selected as the first application to be evaluated.
Research on pilot assistance systems at Eurocopter has lead to the development of an automatic 4D flight path control as part of a prototype pilot assistance system aboard an EC145 demonstrator. The series 3-axis Automatic Flight Control System (AFCS) of the helicopter has, therefore, been upgraded to a 4-axis configuration with automatic control of the heave axis. Automatic flight path control has been achieved with a dedicated upper mode, which is available for cruise flight at airspeeds above 30kt. This mode receives guidance commands from a computer of the pilot assistance system that hosts the guidance algorithms and acts as interfacing module between the flight path planner of the assistance system and the AFCS. Flight paths are defined as sequences of basic trajectory elements from a library. A distance-based analytical formulation of these elements has been chosen, thus allowing a simple and efficient description of versatile 4-dimensional flight paths. Performance of both 4-axis operation and automatic flight path control were successfully demonstrated during simulator campaigns and flight tests.
This paper presents the design of an inner-loop state-space control system for an unmanned helicopter in forward flight. It is assumed that the outer loop of the flight control system forms the desired velocities and turn rate based on flight path parameters such as altitude error, speed error, and cross track error. These desired velocities and turn rate are in the heading frame which rotates about the down (z) axis so that the x axis follows the helicopter heading and the x-y plane remains tangent to the Earth's surface. The helicopter model that is used to design the inner-loop control law is represented in the body-fixed coordinate frame, so the heading frame commands are transformed into the body frame using the current aircraft Euler roll and pitch angles. This transformation adds feedback to the system and can reduce stability margin even to the point of instability. This paper quantifies the additional dynamics from the transformation of commands, and develops a method to adjust the inner-loop control gains to account for the additional feedback, thereby returning the closed-loop eigenvalues and eigenvectors to the values intended by the inner-loop design.
This document recommends criteria for Airborne Windshear Systems, including operational objectives, characteristics, and functional requirements. The recommendations in this document apply to transport aircraft, and describe the operational objectives of windshear alerting systems, situational displays, guidance systems, and avoidance/ detection systems.
This SAE Aerospace Recommended Practice (ARP) recommends criteria for the design and installation of Head-Up Display (HUD) systems. The recommendations are applicable to HUD systems for transport category aircraft, which display flight information (focused at infinity) in the forward field of view. The HUD total system requirement recommendations shall primarily lead to certifiable fail-passive CAT III characteristics and performance. This document forms a part of these recommendations. This document does not address devices for peripheral vision of displays worn by the pilot, nor the presentation of Enhanced Vision System (EVS) information.
This document recommends criteria and requirements for a Flight Management System (FMS) for transport aircraft. The FMS shall provide the functions of Lateral Navigation, Vertical Navigation, and Performance Management and may include Time of Arrival Control. The FMS design shall take Human Factors considerations into account to produce a fault tolerant system.
This paper addresses some EUROCOPTER state of the art advances in the field of efficient algorithms enabling to compute obstacle contour line (OCL) or safety line for a manually-flown rotorcraft flying with a low-level trajectory. Extensive simulation and flight tests were conducted to develop and test a complete set of algorithms for terrain-following or contour flight, and more particularly to improve means of computing a reference OCL for a terrain-following rotorcraft. All practical experimentation was performed using two actual LIDAR OWS (Obstacle Warning Systems) fitted on an “all weather helicopter” of type EC155. In addition, a wire detection algorithm was designed and simulation tested using real flight test data.
This paper describes the latest in a series of helicopter flight trials jointly conducted between the National Research Council of Canada and QinetiQ, Farnborough, UK in October/November 2005. The trial was funded by the UK MoD Day Night All Weather (DNAW) Helicopter Operations Research Programme and conducted under the auspices of The Technical Co-operation Programme (TTCP). The trial had three principal objectives: a) the use of advanced conformal symbology in a tactical context, b) the derivation of advanced symbology as an aid to Approach to Hover guidance and c) the usage of Terrain Following guidance optimised for the aircraft dynamics displayed using Display Night Vision Goggles (DNVGs). All assessments were completed in a simulated Degraded Visual Environment (DVE). This was achieved in day Visual Meteorological Conditions (VMC) using an optical attenuator to artificially degrade the Assessing Pilots (APs) vision of the outside world. The first objective builds on work reported at this Forum in 2005 on Pathway in Sky symbology displayed using DNVGs [1]. Trial SNOWGOOSE used similar guidance to enable the pilot to conduct tactically representative flying in the 300ft and 200ft AGL / 80 knots speed regime and to use the system interactively, for example, to identify and designate targets, avoid threats and identify potential confined area landing zones in DVE. The second objective demonstrates how conformal and standard symbology may be used to aid the pilot in controlling speed and attitude in the approach to hover phase. The study concludes that the combination of pathway symbology, a conventional pitch ladder display and a speed error tape provides good speed control cues. Finally, the work reports on the Flight Trials of the QinetiQ Helicopter Terrain Following (HTF) system which is a continuation the simulator based studies presented under the heading of Intelligent Flight Path Guidance (IFPG) at the same Forum in 2005 [2]. This study demonstrated the system in a number of configurations, both as a stand-alone free flight aid and used in conjunction with pre-planned pathway in sky guidance. Flights were conducted in realistic terrain and against synthetic terrain designed to exercise the dynamic range of the guidance algorithms. The study concludes that routes smoothed using the HTF algorithms are easier to fly, particularly when used in conjunction with a Quickened Flight Path Marker.
Intelligent Flight Path Guidance (IFPG) encompasses a range of technologies with the aim of enabling rotorcraft tactical, nap of the earth flight in any visual environment, in particular, in poor visibility and low light. Trajectory generation methods have been developed that allow continuous regeneration of a detailed spatial trajectory, taking account of the aircraft state and any variation in its performance limits – such as climb rate achievable within torque and rotorspeed constraints. The pilot is directed to follow the generated trajectory by means of a directed flight path marker, combined with additional supporting symbology. The symbology set is incrementally converging towards more advanced sets. Pilot workload and vehicle safety are further improved by means of Tactile Cueing functions, used to prevent and contain aircraft limit exceedances. As a result, the cues serve to prevent the possibility of Controlled Flight Into Terrain (CFIT). At each stage, the development concepts have been evaluated in ground-based, piloted simulation and the results have been used to direct the next stage of system evolution. The guidance and symbology concepts are intended to progress towards flight trials in 2005.
A two-week flight test effort was conducted in September 2003 at a remote location at Eglin Air Force Base in Florida. Dubbed “Acoustic Week”, the test was sponsored by the Chicken Little Program Office and the National Ground Intelligence Center. The test was designed to examine the effectiveness of data collection techniques for a variety of sensors, while simultaneously collecting signature data for a variety of aircraft. Eight aircraft were tested including two rotorcraft from the United States Army Lead The Fleet program, a Navy fixed wing unmanned air vehicle (UAV), a prototype rotary wing UAV, and four civil helicopters. Sensors included acoustic and seismic arrays, infra-red measurement devices, and a human sound jury. Essential vehicle position data were acquired by five different organizations using five different systems of varying accuracy and quality. The focus of this paper is the GPS tracking system used by an Army/NASA/Boeing test team to provide flight path guidance cues, as well as to acquire precise vehicle position data, for two of the test vehicles. The measurement technique used to obtain vehicle source noise hemispheres and the use of these noise hemispheres to predict ground noise footprints is discussed and the need for precise vehicle position data and precision flight tracks is investigated. A detailed description of GPS tracking systems, sources of analysis errors and data accuracy degradation, and the criticality of instrumentation installation on system performance are provided. Flight track results document the improvement in deviations from the desired flight track when guidance cues are provided by course and glide slope deviation indicators rather than the typical ground reference cues.
Electronics play an important role in unmanned aerial vehicles designated for intelligence, surveillance, and reconnaissance mission areas, as well as for combat. Roadmaps seem to be everywhere these days. Earlier this year, Dyke Weatherington, Deputy, Office of the Secretary of Defense, Unmanned Aerial Vehicle Planning Task Force, announced the release of the 2002 Unmanned Aerial Vehicle Roadmap. According to Weatherington, one of the specific purposes of the document, which looks out to 2027, is to identify “those near-term mission areas that can be impacted significantly by emerging UAV technology.” Another goal for the roadmap is its use as “a guide to our industry and allies, identifying the highest value areas for independent investment and areas for international cooperation,” said Weatherington. Ironically, it is international uncooperation that has made UAVs increasingly important for a wide range of armed forces mission scenarios-particularly ISR, or intelligence, surveillance, and reconnaissance-proving especially useful because they can be launched from secure positions to perform military tasks in a dangerous environment.
This paper discusses the development and simulation of control law features that enhance handling qualities in shipboard environments and in degraded visual conditions. The control law technologies developed in this paper are intended to improve mission effectiveness and safety while expanding the maritime operational envelope of tiltrotor aircraft. The major control law features discussed in this paper are (1) improved hover, speed, and altitude capture and hold junctions, (2) a Vortex Ring State (VRS) tactile cueing system, (3) automated flight path control during terminal area operations in degraded visual conditions, and (4) phase compensating rate limiter architectures that minimize input-to-output phase loss while limiting the rate of control inputs to allowable levels. The philosophy of the control laws discussed in this paper is to offer seamlessly integrated and failure benign augmented flight control modes using regime recognition. Velocity stabilization functions are automatically engaged or disengaged without button pushes. Piloted simulation of these control law features in the high fidelity Boeing V-22 simulation facility is discussed in this paper.
This paper discusses the development and simulation of control law features that enhance handling qualities in shipboard environments and in degraded visual conditions. The control law technologies developed in this paper are intended to improve mission effectiveness and safety while expanding the maritime operational envelope of tiltrotor aircraft. The major control law features discussed in this paper are (1) improved hover, speed, and altitude capture and hold functions, (2) a Vortex Ring State (VRS) tactile cueing system, (3) automated flight path control during terminal area operations in degraded visual conditions, and (4) phase compensating rate limiter architectures that minimize input-to-output phase loss while limiting the rate of control inputs to allowable levels. The philosophy of the control laws discussed in this paper is to offer seamlessly integrated and failure benign augmented flight control modes using regime recognition. Velocity stabilization functions are automatically engaged or disengaged without button pushes. Piloted simulation of these control law features in the high fidelity Boeing V-22 simulation facility is discussed in this paper.
This paper discusses the development and simulation of control law features that enhance handling qualities in shipboard environments and in degraded visual conditions. The control law technologies developed in this paper are intended to improve mission effectiveness and safety while expanding the maritime operational envelope of tiltrotor aircraft. The major control law features discussed in this paper are (1) improved hover, speed, and altitude capture and hold functions, (2) a Vortex Ring State (VRS) tactile cueing system, (3) automated flight path control during terminal area operations in degraded visual conditions, and (4) phase compensating rate limiter architectures that minimize input-to-output phase loss while limiting the rate of control inputs to allowable levels. The philosophy of the control laws discussed in this paper is to offer seamlessly integrated and failure benign augmented flight control modes using regime recognition. Velocity stabilization functions are automatically engaged or disengaged without button pushes. Piloted simulation of these control law features in the high fidelity Boeing V-22 simulation facility is discussed in this paper.
Flight directors and autopilots have been successfully integrated into fixed and rotary wing aircraft for many years. Flight directors perform the basic task of translating flight guidance commands into a logical set of display symbology. The pilot responds to the display symbology and applies control system inputs to guide the aircraft along a desired flight path. A principal flight director design objective is to provide the pilot with precise flight path control and low workload, particularly when operating at night and/or in Instrument Meteorological Conditions (IMC). This paper discusses limitations of standard flight director symbology for the tiltrotor application and a design approach to supplement standard flight director symbology with nacelle control augmentation to accommodate the unique control characteristics of tiltrotor aircraft. An overview of the MV-22 tiltrotor flight director system is provided along with a description of three candidate types of nacelle control augmentation that were evaluated using man-in-the-loop simulation at the Boeing Flight Simulation Lab (FSL). This paper summarizes the results of an engineering trade study conducted to determine a nacelle control augmentation design approach for the MV-22 flight director system.
This document recommends criteria for Airborne Windshear Systems, including operational objectives, characteristics, and functional requirements. The recommendations of the document apply to transport aircraft, and describe the operational objectives of windshear alerting systems, situational displays, guidance systems, and avoidance/detection systems.
A piloted simulation experiment was conducted in the NASA Ames Research Center Vertical Motion Simulator to investigate the use of integrated cockpit displays in terminal area operations for Category A civil rotorcraft. Category A is the transport category of rotorcraft which are required to be able to recover from an engine failure and continue flying. The UH-60 Black Hawk model was used for the simulation with some modifications made to the power available to simulate a civil rotorcraft. Hovering backups were flown from a confined area, raised vertiport site to a takeoff decision point (TDP), followed by normal flyout. Pilots flew the task with the standard Black Hawk instrument set or with one of two integrated formats presented on a color panel-mounted display. Engine failures were randomly inserted between takeoff and the TDP region both slightly before, and slightly after, the TDP. For an engine failure occurring prior to the TDP, the pilot made a visual landback to the pad. For one occurring after the TDP, the pilot continued the flyout. Weather conditions were varied from calm, clear conditions to low visibility and ceilings with cross-winds and turbulence. Evaluations were conducted with six pilots. Objective and subjective data describing task performance and pilot workload were collected. The pilots were able to maintain more precise flight path control during the backup with the integrated display. This precise control placed the pilot in a better situation from which to handle an engine failure. Pilot recognition of the TDP location was also highly improved with an integrated display. Emergency landbacks, on runs using the integrated display during the backup portion, were all performed within the specified tolerances. Some of the land-backs using the standard instrument set, however, exceeded the adequate performance parameters. Cooper-Harper Handling Qualities Ratings (HQR) confirmed that pilot workload was reduced and pilots were able to fly more consistently within the desired performance parameters with the integrated display than with the standard instruments and visual cues.
The recovery of helicopters to small ships is a demanding task, particularly at night, in poor visibility or in adverse wind and high sea states. A significant number of technical problems need to be overcome to reduce current operational limitations. These include locating the ship, especially when operating under emission controlled conditions, establishing recovery profiles which minimise the helicopter handling and pilot workload problems at low airspeeds in beam and tail wind situations, and presenting information to the pilot to maintain a high sense of situation awareness. This paper reports on the research being carried out by the Defence Research Agency to reduce the limitations on large helicopters operating from small ships. The major elements of the work are the development of a Relative GPS/INS based guidance system, the generation of "adaptive" approach profiles, precision automatic helicopter flight path control throughout the speed range with flight director and map based display available as reversionary modes. The paper describes the status of the guidance, display and autopilot systems in use, and reports on the results of an interim ship trial carried out in early 1994.
This document recommends criteria and requirements for a Flight Management System (FMS) for transport aircraft.
This document recommends criteria for Airborne Windshear Systems, including operational objectives, characteristics, and functional requirements. The recommendations of this document apply to transport aircraft, and describe the operational objectives of windshear alerting systems, situational displays, guidance systems, and detection/avoidance systems.
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