摘要:

ABSTRACTDifferent techniques have been proposed for combining GPS and inertial sensor information, and recent published findings seem to indicate that primary‐means integrity availability is achievable with standard 2 nmi/h (95 percent) inertial sensor performance. This paper investigates and quantifies the different inertial effects that contribute to enhanced integrity of the integrated GPS/inertial system, such as coasting or Schuler feedback. A Kalman filter‐based integration scheme that preserves the integrity information in an optimal fashion is presented and used to quantify integrity performance. This paper also proposes an approximate model, incorporating the main inertial effects contributing to integrity, that can be used to calculate the achievable horizontal protection level (HPL) at any geographical location and time. This model is used to estimate the availability of fault detection for an integrated GPS/inertial system. In addition, the paper compares the availability of fault detection for the GPS/inertial system with that for other augmentations to provide trade‐off inform

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1996.tb01920.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACTThe requirements for a feasibility demonstration program are presented. Navigation sensor error versus total system error selection is discussed. The Automatic Landing System (ALS) is described, with its objective to demonstrate augmented differential GPS with kinematic carrier‐phase tracking (KCPT) technology, and its ability to meet Category (CAT) IIIb autoland requirements for navigation sensor error (NSE) and integrity. Key features of the ALS are presented and discussed. Significant system strengths include the KCPT fast ambiguity resolution method, carrier‐phase tracking accuracies, and the integrity monitoring and probabilities of missed detection made possible by these accuracies. The flight test description and results of the series of 100 precision completed approaches and landings are presented. Analysis of the approaches from the final approach fix through touchdown is inclu

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1996.tb01921.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACTThe concept of using a pseudolite in the reverse mode where the pseudolite is positioned with respect to receivers deployed at known points is presented. Two types of double‐difference positioning approaches for eliminating clock and other code and carrier‐phase biases are described and analyzed—pseudolite positioning with satellite reference (PPSR) and pseudolite positioning with pseudolite reference (PPPR). Results are given for an initial test conducted in a land vehicle at Holloman AFB, New Mexico. The test range consisted of a 600 m course surrounded by six receivers deployed in a noncoplanar configuration at distances ranging from 100 to 1,500 m from the vehicle. The pseudolite position was calculated using both integer and floating‐point carrier‐phase ambiguities, and the resulting trajectory was analyzed to assess the differential positioning performance of this inverted G

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1996.tb01922.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACTOperating heavy equipment can be a difficult and very tedious task. Control of an agricultural tractor requires the continuous attention of the driver, and farmers often work long hours during critical times of planting and harvesting. Loaders and other ground vehicles are frequently used in situations that are unpleasant or even hazardous for a human operator.This paper explores the use of carrier‐phase DGPS as the sole position and attitude sensor in closed‐loop control of farm and construction vehicles. A land vehicle optimal control system was designed and simulated using realistic plant, sensor, and disturbance models. To validate this simulation, a GPS‐equipped electric golf cart was driven to high accuracy under automatic steering control. Golf cart experimental data were examined in post‐processing to determine the feasibility of on‐line system identification

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1996.tb01923.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACTCarrier‐phase GPS techniques are capable of measuring positions with subcentimeter accuracy. With several antennae, carrier‐phase GPS can be used to determine attitude. This paper presents a motion‐based algorithm for resolving the integer ambiguities that is suitable for conditions of poor satellite visibility. In particular, this algorithm can use baselines with fewer than three common satellites visible. This algorithm was used very successfully in practice as the attitude sensor for an autonomous model helicopter and air

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1996.tb01924.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACTThe stereographic projection is currently used for the representation of airborne targets on a situation display. A radar reports positions of targets within its range, in polar coordinates with respect to the radar site. In an area scanned by many radars, targets need to be represented in a single (stereographic) plane, and this is done via mathematical transformation from the local frame of reference to the common plane.The stereographic projection is conformal (that is, angle‐preserving). Two additional conformal projections are considered by the authors for use in air traffic control, and it is demonstrated that (1) the mathematics needed to accomplish their transformation to the common plane is simpler than it is for the stereographic projection, and consequently the computation load is lighter (this may be critical during heavy traffic); (2) there is no loss in precision; and (3) in the case of Lambert conformal conical projection, there is the additional advantage of being able to use an ellipsoidal instead of a spherical eart

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1996.tb01925.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY