Christine M. Haissig

GASPER/AILS: an integrated DGPS/ADS-B airborne alerting system for closely spaced parallel approaches

This paper describes work performed by Honeywell and NASA Langley Research Center to research, develop, and flight-test the Closely Spaced Parallel Approach (CASPER)/Airborne Information for Lateral Spacing (AILS) technology. GASPER/AILS is an airborne alerting system, which provides separation assurance between aircraft during approaches to closely spaced parallel runways in instrument meteorological conditions (IMC). The result of this system solution is the preservation of visual-meteorological-condition (VMC) arrival rates during IMC-as well as enhanced safety. Flight tests of this system were conducted at Wallops Island, VA in the summer/fall of 1999 using NASAs 757 research aircraft and Honeywells Gulfstream GIV. This activity led to proof-of-concept demonstrations held at Minneapolis/St. Paul International Airport in November 1999.

Adaptive fuzzy temperature control for hydronic heating systems

This paper describes an innovative adaptive fuzzy control (AFC) algorithm for regulating the room temperature in a hydronic heating system. The hydronic heating system consists of a boiler that provides central heating water to a radiator or radiators in a home or apartment. Room temperature is regulated with a motor that drives a variable-position valve on each radiator that controls the flow of hot water through the radiator. The AFC automatically learns the steady-state radiator valve positions for five operating set points and uses this information in a fuzzy controller that commands the radiator valve position. Laboratory tests under typical operating conditions show that the AFC simultaneously improves the control quality while reducing the battery consumption when compared with a conventional proportional-integral (PI) feedback controller. For a 70-hour laboratory test with typical operating set points, the control quality increased 32% while the estimated battery consumption decreased 35%. The AFCs memory and processing requirements are suitable for embedded microprocessors, so it is a realistic replacement for a conventional PID algorithm.

An Adaptive Fuzzy Algorithm for Domestic Hot Water Temperature Control of a Combi-Boiler

This paper describes an innovative adaptive fuzzy control (AFC) algorithm for regulating the domestic hot water temperature of a combi-boiler or instantaneous hot water heater when using a domestic hot water flow rate sensor. The AFC automatically learns the feedforward relationship between the domestic hot water flow rate and the gas valve position and adapts to process changes such as variations in the inlet water temperature, controller set point, gas composition, and flow sensor miscalibration without requiring additional sensors or a system identifier. Laboratory tests under typical operating conditions show that the AFC reduces the set-point error between 18% and 70% and reduces control effort between 23% and 41% when compared with a conventional proportional-integral-derivative (PID) feedback controller with feed-forward compensation. The AFCs memory and processing requirements are comparable to those for a PID plus feedforward algorithm, so it is a realistic replacement for a conventional PID algorithm with feedforward compensation.

Tuning fuzzy feedback controllers using the circle criterion

This paper illustrates a method for tuning fuzzy feedback controllers using the circle criterion. The method can be used for design, tuning at commissioning, or online adaptation of systems consisting of a fuzzy feedback controller and a process that can be modeled as approximately linear or piecewise linear. The general tuning methodology is developed by extending the concepts of gain and phase margin from classical control. It is illustrated using a fuzzy proportional feedback controller with feedforward compensation. The paper shows that the key tuning parameter for stability is the ratio of the universe of discourse for the error input and the universe of discourse for the control output.

Using TCAS surveillance to enable legacy ADS-B transponder use for in-trail procedures

In-Trail Procedures (ITP) is an application of Automatic Dependent Surveillance-Broadcast (ADS-B) that allows aircraft to change flight levels in areas where current non-radar separation standards would prevent desirable altitude changes. The ITP avionics receive ADS-B Out position reports from aircraft at intermediate flight levels that could be blocking the desired climb or descent maneuver. The most recent standard for ADS-B broadcast is RTCA/DO-260B [1]. This is also known as Version 2. Equipage is mandated by 2020 in the US for the same aircraft that carry transponders. Equipage is mandated in Europe by 2015 for forward fit aircraft and by 2017 for retrofit aircraft. Standards have been developed for the ADS-B data accuracy requirements for ITP [2, 3]. The standards are straightforward to apply to aircraft equipped with transponders certified to DO-260B [1]. The standards are less straightforward to apply for aircraft equipped with transponders certified to the earlier standards of ADS-B, which are known as Version 0 or Version 1 [4, 5]. This paper shows that crosschecking ADS-B data with Traffic Alert and Collision Avoidance System (TCAS) data is an effective mitigation technique for uncertain ADS-B horizontal position accuracy and integrity for legacy Version 0 and Version 1 ADS-B transponders.