Onboard Guidance System Research Articles

Improving the performance of a stability monitoring system by adding wave encounter frequency estimation

Onboard guidance systems have emerged to improve the safety of fishing vessels providing the skipper with simplified stability information. In the last years, the authors have developed a stability monitoring system that automatically estimates the natural roll frequency of the vessel. Although the performance was acceptable, there were some specific situations where the influence of external excitations reduced the accuracy of the stability estimations. In this work, a methodology to automatically estimate the wave encounter frequency from ship motions is proposed. Then, this methodology is included in the stability monitoring system. Towing tank tests of a mid-sized stern trawler in different conditions have been used to analyse the improvements obtained with this approach.

Onboard guidance system design for reusable launch vehicles in the terminal area energy management phase

A terminal area energy management (TAEM) guidance system for an unpowered reusable launch vehicle (RLV) is proposed in this paper. The mathematical model representing the RLV gliding motion is provided, followed by a transformation of extracting the required dynamics for reference profile generation. Reference longitudinal profiles are conceived based on the capability of maximum dive and maximum glide that a RLV can perform. The trajectory is obtained by iterating the motion equations at each node of altitude, where the angle of attack and the flight-path angle are regarded as regulating variables. An onboard ground-track predictor is constructed to generate the current range-to-go and lateral commands online. Although the longitudinal profile generation requires pre-processing using the RLV aerodynamics, the ground-track prediction can be executed online. This makes the guidance scheme adaptable to abnormal conditions. Finally, the guidance law is designed to track the reference commands. Numerical simulations demonstrate that the proposed guidance scheme is capable of guiding the RLV to the desired touchdown conditions.

Guided underwater object

A guided underwater object (GUO) ( 100 ) comprises steering means, an on-board guidance system ( 200 ) for controlling the steering means, and a hydrophone unit or units ( 104 A, 104 B, 104 C, 104 D, 104 E, 104 F, 104 G, 104 H) arranged to pass signals induced therein by an acoustic guiding beam to the on-board guidance system to effect directional control of the self-propelled underwater object. The GUO is guided by a remote guidance system characterised by a plurality of transmitter arrays ( 402 A, 402 B, 402 C, 402 D; 412 A, 412 B, 412 C, 412 D; 422 P, 422 Q, 422 R) arranged to transmit a plurality of contiguous acoustic beams ( 302 A, 302 B, 302 C, 302 D) each having a different frequency or frequency chirp (or other acoustic signal coding) and enclosing a guidance corridor of lower sound level (‘null’) ( 304 ) extending approximately in the direction of propagation of the acoustic beams and defining a flight path of the object. The GUO requires no on-board search sensors, no communications link with the guidance system and is of low cost.

Evaluation of Onboard Taxi Guidance Support on Pilot Performance in Airport Surface Navigation

Advanced Surface Movement Guidance and Control Systems (A-SMGCS) comprise a range of new technologies for both the flight deck and ground air traffic control and is supposed to enable increased safety and a more efficient throughput at presently highly congested major airports. A flight deck A-SMGCS module is the onboard guidance system TARMAC-AS. This module consists of controller pilot data link communication (CPDLC) and an electronic moving map (EMM), which also serves as a cockpit display of traffic information (CDTI). TARMAC-AS is evaluated in an investigation involving 49 commercial pilots who performed a series of approach, landing and taxiing simulation trials under varied visibility, which were completed in a fixed-base cockpit simulator. Results support the notion that an EMM + CPDLC + CDTI improve the effectiveness of taxi navigation. A potential negative impact of observed increased head-down times to the compelling TARMAC display on unexpected outside scene obstacle detection was not substantiated.

High-Precision Navigation and Guidance Systems of Aerial Vehicles is the Use of Computer Vision Technologies

The report discusses conceptions and problems of construction of independent high precision navigation systems for aerial vehicles based on “computer vision” technologies: methods and technologies of reference images forming, on-board algorithms to combine both reference and current images for the localization of the ground scene objects and for the definition of their coordinates, algorithms of quasi-optimum (poliGaussian) estimation of phase coordinates of onboard guidance system.

Mixing four-dimensional equipped and unequipped aircraft in the terminal area

The problem of mixing four-dimensional (4-D) equipped aircraft (aircraft equipped with onboard guidance systems that can predict and control the touchdown time of an aircraft to an accuracy of a few seconds throughout the descent) with unequipped aircraft in the terminal area has been investigated via a real-time air traffic control simulation study. The objective of this study was to develop scheduling algorithms and operational procedures for various traffic mixes that ranged from 25 to 15% 4-D equipped aircraft. Results indicate substantial reduction in controller workload and an increase in orderliness when more than 25% of the aircraft are 4-D equipped. Moreover, this is accomplished without increasing the workload or adding delays for the unequipped aircraft.

Space guidance evolution - A personal narrative

Introduction T prospect of preparing a comprehensive history of space guidance and navigation was, initially, a delight to contemplate. But, as the unproductive weeks went by, the original euphoria was gradually replaced by a sense of pragmatism. I reasoned that the historical papers which had the greatest appeal were written by old timers telling of their personal experiences. Since I had lived through the entire space age, and had the good fortune of being involved in many of the nation's important aerospace programs, I decided to narrow the scope to encompass only that of which I had personal knowledge. (It is, however, a sobering thought that you might qualify as an ' 'old timer.) The story begins in the early 1950's when the MIT Instrumentation Laboratory (later to become the Charles Stark Draper Laboratory, Inc.) was chosen by the Air Force Western Development Division to provide a self-contained guidance system backup to Convair in San Diego for the new Atlas intercontinental ballistic missile. The work was contracted through the Ramo-Wooldridge Corporation, and the technical monitor for the MIT task was a young engineer named Jim Fletcher who later served as the NASA Administrator. The Atlas guidance system was to be a combination of an on-board autonomous system, and a ground-based tracking and command system. This was the beginning of a philosophic controversy, which, in some areas, remains unresolved. The self-contained system finally prevailed in ballistic missile applications for obvious reasons. In space exploration, a mixture of the two remains. The electronic digital computer industry was in its infancy then, so that an on-board guidance system could be mechanized only with analog components. Likewise, the design and analysis tools were highly primitive by today's standards. It is difficult to appreciate the development problems without considering the available computational aids.

Translunar Midcourse Guidance

Optical and midcourse guidance and navigation requirements for the lunar mission are outlined. Techniques for meeting these requirements using an on-board guidance system are briefly described. Investigation of phenomena capable of providing navigation measurements are summarized. Instrumentation for possible use in orbital and midcourse navigation sightings is gellerally described.