Intelligent Surveillance and Management Functions for Airfield Applications Based on Low Cost Magnetic Field Detectors
Various systems have been developed for ground aircraft detection and surveillance. All these sensors have their own disadvantages.
- surface Movement Radar (SMR) systems are extremely expensive to purchase and operate (prohibitively so for many regional and smaller airports) and are subject to masking and distortion in the vicinity of airport buildings, terrain or plants;
- optical detection systems are severely degraded under adverse weather conditions, however these are precisely the conditions in which optimum surveillance is required for safety;
- airport Surface Detection Equipment (ASDE) suffers from significant problems with reflections and multi-path phenomena, and gaps in surveillance coverage;
- the newly-introduced multi-lateration systems will only work with transponder-equipped aircraft. They will not detect non co-operative vehicles or aircraft that are not equipped with such a transponder, or with a failed or malfunctioning transponder, precisely the conditions often found at regional and smaller airports. This is a potential safety hazard if they are used as the sole means of maintaining separation and control. The same applies to GPS based systems, that cannot provide the necessary reliability in terms of availability, continuity and integrity;
There was a strong demand for a new sensing technology, in particular for smaller/regional airports that need to respond to increasing demand for movement rates and commercial requirements, whilst wishing to maintain safe operation in low visibility, who cannot afford the multi-million Euro investment in a traditional Surface Movement Radar (SMR) or a fully integrated A-SMGCS.
The objective of this project was to determine whether recent advances in magnetic sensors could provide a better means of surface movement surveillance at airports, either as a cost-effective alternative to Surface Movement Radar for smaller airports or as an additional point sensor in multi-sensor Advanced Surface Movement Guidance and Control Systems (A-SMGCS) at major international airports. Therefore a new detector technology shall be developed and integrated into advanced surface movement guidance and control systems (ASMGCS). On this basis ISMAEL aims at improving existing installations of ASMGCS at large airports as well as enabling the installation of appropriate ASMGCS at small and medium airports in Europe.
ISMAEL had the following methodology:
- ISMAEL captured the requirements for an effective and usable system from a technical (e.g. functional, performance and safety), economic (e.g. equipment, installation and operational costs) and legal (e.g. liability, safety regulations) point of view. It is important to understand the demands for such a system and in particular the levels of performance and dependability required to support the functions that operational users require.
- ISMAEL developed appropriate hardware prototypes for magnetic field sensors and investigate the theoretical fundamentals of the physical phenomenon of magneto resistant materials. Special attention was given to model the excitation of the sensor signals due to vehicles passing the sensor and to suppress disturbing influences from environmental conditions or sources. This function can be assessed by e.g. the detection rate for all passing vehicles in the field trials. The determined parameters for the aspect of missed detection as well as false alarm were kept rather small. The later indicators will refer to the objective of safety, in order to deliver a reliable detector.
- ISMAEL developed and applied complex algorithms for the necessary data processing that are capable of detecting and identifying vehicles and providing important parameters about their motion, like velocity, direction, etc. This stage of the development embeds the sensor head into a complete detector module. Here the objective of determining the quality of speed and direction can be measured by the delivered accuracy, which will be indicated with appropriate stochastic parameters about the computed errors of these states.
- ISMAEL investigated the integration of the developed detector module into complete systems for airport applications by developing a solid concept for combining the detector with other information sources like radar and flight data etc. to explore the potential benefits of the new technology for enhancements of existing systems as well as for new systems.
- ISMAEL established how this new detector technology is able to satisfy the requirements, through practical experiments and trials in an airport environment, to assess where further work or investigation is required. This issue has to be derived from the input of experts on the topic of airport operation. The relevant objectives and indicators were defined in the assessment plan (D12).
- ISMAEL provided a socio-economic evaluation of the impacts o
There were three key results from the project:
- Magnetic detector
- SDF software
- Test analysis software
The development of magnetic detectors aims to determine whether recent advances in magnetic sensing can provide improved surface movement surveillance at airports. The detection of targets moving on the airport surface is achieved by detecting their ferromagnetic parts such as vehicle motors or aircraft engines and gears, based on their interaction with the earth's magnetic field. This property can be used to detect and locate objects, either using a single point detector or an array of detectors. A system based on an array of detectors can provide reliable object velocity and direction information unaffected by weather conditions, shadowing or reflection effects. Also, the proposed system has the ability to classify detected targets into two main classes i.e. aircraft and cars. Detection ability of magnetic detectors is not influenced by weather, temperature and brightness. The system based on magnetic detectors is passive (non-co-operative), has low power consumption, no radiation and no influence to airport communication. Magnetic detectors have been tested in Thessaloniki airport and Frankfurt airport for runway incursion, tracking and gate management. Systems based on magnetic detectors may serve as 'gap filler' for areas where existing surveillance techniques are not effective, or as a low-cost alternative to radar or multi-lateration at smaller airports. The solution is also very appropriate for the prevention of runway incursions.
The SDF (sensor data fusing) software collects data about the state of magnetic detectors that are connected to the SDF server in real time and processes this data in order to extract observations (plots) and tracks. It provides information about the position and speed of targets, the date and time of detections and the size of the targets. The communication between SDF server and the network of magnetic sensors is based on an RS-485 protocol. The final results of the SDF software are encoded in Asterix Cat.10 format and are transmitted as UDP Ethernet packets. An optional visualization window is also available, showing detector states (inputs) as well as generated observations and tracks on the airport map. One of the benefits of the proposed approach is that it addresses a problem associated with the standard 2-D Constant Velocity (CV) motion model, i.e. that it allows each target to move freely within the ground plane
The project produced the following key technical recommendations:
- Investigate the trade-off between position accuracy and coverage. This issue is of major influence on the number of detectors needed for a certain application and the options for integrating them into AGL mountings;
- Improve the detector performance and reduce the detector size toward the target system-on-chip;
- Analyse possibilities for installing detectors into AGLs, cable ducts, or slots in the concrete on the taxiway surface, while maintaining favourable signal to noise ratio;
- Investigate the use of AGL power-lines for data communication;
- Integrate with cooperative system (multilateration, secondary radar) for mobile identification and/or perform some kind of classification of the mobiles detected based on magnetic signatures;
- Take opportunity of additional test site to compare ISMAEL to competing solutions;
- Perform extensive testing to prove robustness, reliability, integrity, MTBF (Mean Time Between Failure), and coverage of the detector for detecting vehicles not driving on the centreline; follow certification requirements for testing;
- Search for cooperation with a partner experienced in certification testing procedures. This is necessary because elaborate testing procedures are mandatory for any system that may deliver data to an A-SMGCS. Exact routines to be followed are still under development by EUROCONTROL and ICAO;
- In software programming follow the safety standards set out in ATM systems in ESARR6 and the ICAO Manual for A-SMGCS [RD 8, 9]. Extensive safety tests are required.
The project produced the following key policy recommendations:
- The objective to increase safety by developing an application to avoid inadvertent runway incursion as well as the application of a block-wise SMGCS are of major importance not only for smaller airports.
- Industry favours cooperation with dedicated SMEs or start-ups in a certain field of expertise since in general know-how is better protected and maintained there than at universities.
- Contacts in the industry have been established. Two manufacturers of airport surveillance tools and a sensor manufacturer entered are interested. Dedicated demonstrations of the ISMAEL system at Frankfurt airport are scheduled. Roadmaps for cooperation are being prepared.
- When further developing ISMAEL from a research demonstrator to an industry prototype and to a commercial product, the standards according to the Appendix of the ICAO Manual for A-SMGCS [RD 7] the following requirements have to be met.
- There are some issues to be solved like installation and maintenance costs, depending on the number of sensors to be installed on the field. The consortium is thinking that the sensor price could decrease in the next years.
- Established systems for vehicle detection (e.g. parking system) and guidance are direct commercial competitors to the developed ISMAEL system.
- Participating in FP7, and the SESAR call respectively, with two or three new projects.
Here are some industry responses:
'Sensors like the one developed in the ISMAEL project are needed to improve radar integrity in sensitive areas of the airfield.'
'We hope that magneto resistive sensors can support airports that will not be in a position to implement a full A-SMGCS.'
'A magneto resistive detector that has proven to work properly in the harsh environment of an airfield is already better than what we have seen so far.'