Flight evaluation of a computer aided low-altitude helicopter flight guidance system

The Flight Systems Development branch of the U.S. Army's Avionics Research and Development Activity (AVRADA) and NASA Ames Research Center developed for flight testing a Computer Aided Low-Altitude Helicopter Flight (CALAHF) guidance system. The system includes a trajectory-generation algorithm which uses dynamic programming and a helmet-mounted display (HMD) presentation of a pathway-in-the-sky, a phantom aircraft, and flight-path vector/predictor guidance symbology. The trajectory-generation algorithm uses knowledge of the global mission requirements, a digital terrain map, aircraft performance capabilities, and precision navigation information to determine a trajectory between mission waypoints that seeks valleys to minimize threat exposure. This system was developed and evaluated through extensive use of piloted simulation and has demonstrated a 'pilot centered' concept of automated and integrated navigation and terrain mission planning flight guidance. This system has shown a significant improvement in pilot situational awareness, and mission effectiveness as well as a decrease in training and proficiency time required for a near terrain, nighttime, adverse weather system

Space shuttle landing navigation using precision distance measuring equipment

Evaluation of precision distance measuring equipment for space shuttle landing navigatio

Design and Analysis of a Navigation System Using the Federated Filter

The purpose of this paper was to design and analyse a federated filter design, to be used for retrofit of an Embedded GPS/INS (EGI) navigation unit into an existing Kalman filter-based air navigation system. A design was selected and simulations were conducted in the Distributed Kalman Filter Simulation software (DKFSIM). As well, a centralized Kalman filter design was simulated under identical conditions for comparison purposes. The federated filter was shown to be a feasible design, with accuracy in position and velocity very close to centralized Kalman filter values. The federated filter design also showed some attractive fault detection and isolation features, superior to the centralized Kalman filter, due to the independent operation of the component Kalman filters. The federated filter was shown to be well worthy of continued study for implementation in air navigation systems, especially where distributed filters are required

A cost-effective adverse-weather precision guidance system

This SAND report documents the results of an LDRD project undertaken to study the accuracy of terrain-aided navigation coupled with highly accurate topographic maps. A revolutionary new mapping technology, interferometric synthetic aperture radar (IFSAR), has the ability to make terrain maps of extremely high accuracy and spatial resolution, more than an order of magnitude better than currently available DMA map products. Using a laser altimeter and the Sandia Labs Twin Otter Radar Testbed, fix accuracies of less than 3 meters CEP were obtained over urban and natural terrain regions

Investigation of advanced navigation and guidance system concepts for all-weather rotorcraft operations

Results are presented of a survey conducted of active helicopter operators to determine the extent to which they wish to operate in IMC conditions, the visibility limits under which they would operate, the revenue benefits to be gained, and the percent of aircraft cost they would pay for such increased capability. Candidate systems were examined for capability to meet the requirements of a mission model constructed to represent the modes of flight normally encountered in low visibility conditions. Recommendations are made for development of high resolution radar, simulation of the control display system for steep approaches, and for development of an obstacle sensing system for detecting wires. A cost feasibility analysis is included

Utilization of Expert Systems in the Work Place: Performing Project Software Cost Estimation on Training Systems

This research report investigates the use of an expert system to aid project engineers at the Naval Training Systems Center in making decisions concerning the requirements of the computer systems used in simulators. For a prototype system domain, the author chose an expert system that would generate a software development cost estimate. This system questions the user about the features and options required on the training system. The expert system then analyzes the information to generate a “lines of code” estimate. A selected model will combine various factors to generate s value answer for the user. The capabilities and features of current expert system development tools are reviewed as to what features would best address this problem domain. EXSYS, a rule-based expert system shell that runs on both Zenith and IBM PCs, was selected to develop the prototype because of its capability to meet the requirements of the software cost estimation domain. The COCOMO estimation model was selected to generate the user answers. The technique of using a rule-based system in combination with other management decision tools, such as spreadsheets, holds a potential of being an excellent approach for providing a tool for storing and utilizing estimation data and heuristics

Autonomous flight and remote site landing guidance research for helicopters

Automated low-altitude flight and landing in remote areas within a civilian environment are investigated, where initial cost, ongoing maintenance costs, and system productivity are important considerations. An approach has been taken which has: (1) utilized those technologies developed for military applications which are directly transferable to a civilian mission; (2) exploited and developed technology areas where new methods or concepts are required; and (3) undertaken research with the potential to lead to innovative methods or concepts required to achieve a manual and fully automatic remote area low-altitude and landing capability. The project has resulted in a definition of system operational concept that includes a sensor subsystem, a sensor fusion/feature extraction capability, and a guidance and control law concept. These subsystem concepts have been developed to sufficient depth to enable further exploration within the NASA simulation environment, and to support programs leading to the flight test

Preliminary Candidate Advanced Avionics System (PCAAS)

Specifications which define the system functional requirements, the subsystem and interface needs, and other requirements such as maintainability, modularity, and reliability are summarized. A design definition of all required avionics functions and a system risk analysis are presented

Efficient transfer of weather information to the pilot in flight

Efficient methods for providing weather information to the pilot in flight are summarized. Use of discrete communications channels in the aeronautical, VHF band or subcarriers in the VOR navigation band are considered the best possibilities. Data rates can be provided such that inputs to the ground based transmitters from 2400 band telephone lines are easily accommodated together with additional data. The crucial weather data considered for uplinking are identified as radar reflectivity patterns relating to precipitation, spherics data, hourly sequences, nowcasts, forecasts, cloud top heights with freezing and icing conditions, the critical weather map and satellite maps. NEXRAD, the ground based, Doppler weather radar which will produce an improved weather product also encourages use of an uplink to fully utilize its capability to improve air safety

Interference Mitigation in Radio Altimeter

Ever since its advent in the late 19th century, wireless technology has evolved substantially. Towards the end of 20th century, wireless system was being considered as a replacement for wired connections between digital avionic systems in an aircraft. Although it seemed to be a possible breakthrough in aviation, it came with its own set of challenges which included interference avoidance with aircraft electronics, dedicated reserved frequency band and many more. Hence, the existing wireless solutions could not be used directly and there is a need to develop specialized solutions. The primary objective of this research is to devise a technique to manage the interference, arising due to the Wireless Avionics Intra-Communication (WAIC) System, in the radio altimeter present in an aircraft. The altimeter along with the in-flight environment has been simulated in MATLAB. Its performance has been evaluated for the scenario when the interference due to WAIC system is introduced. Also, various techniques which utilize vacant bandwidth of the altimeter to aid the avionics intra-communication, thus managing the interference for the altimeter, have been analyzed