Design of detailed specifications for human performance modeling, using MIDAS, of flight crew and controller behavior in an en route sector with CAT. These specifications were only partially coded into MIDAS due to effort required to design and implement the messaging and networking process necessary for the RFS-MIDAS linkage.
Linkage of the RFS and MIDAS simulations, with the MIDAS flight crews and controller providing micro-level representations of the corresponding RFS flight crews and controller, implemented on a suite of computer processors using the HLA interface standards and RTI software.
Demonstration of the RFS-MIDAS linkage by simulating the RFS controller of the non-subject sector and the RFS-wrapped MIDAS controller of the subject sector interacting with each other and with the RFS-wrapped MIDAS flight crew of a single, sensor-equipped aircraft being handed off into and transiting the subject sector, encountering turbulence events and issuing associated PIREPs, and being handed off out of the sector. One PIREP was issued when the aircraft experienced a moderate turbulence event that began with the aircraft already in the turbulent region, thus without the lookahead benefit of the sensor. Another PIREP was issued by the pilot based on a sensor alert about an area of severe turbulence ahead. CAT avoidance maneuvers were not simulated in this test. The single-aircraft test demonstration highlighted the need, in order to fully simulate the sector traffic, for refinement of the RFS and MIDAS agent models and the networking interface procedures for improved runtime performance, resolution of synchronization issues, and completion of the human performance modeling of the flight crew and controller procedures.
Observations
We make the following observations based on our experiences setting up and executing the dynamic RFS-MIDAS linkage for the CAT sensor scenario:
General
1. The above objectives were met by marrying two modeling systems that were designed and implemented for different purposes and using different modeling and programming paradigms. Some of the challenges encountered in doing so included, for example, networking three software systems (the RFS and MIDAS simulations and the RTI middleware) running on two hardware platforms, passing messages among the three that are understandable to each, and synchronizing the timing between two independently running simulations.
2. A critical requirement for an effective linking of two or more simulation systems into a single dynamic system is that they all be continually synchronized in simulated time – i.e., that one does not get ahead of or fall behind the others with respect to the timing of interactions between them. A workaround algorithm was instituted to approximately meet this requirement for the single-aircraft case simulated with the RFS-MIDAS system, but a more general, permanent solution is needed. Such a solution may involve a sort of “super executive” that maintains a master clock and controls the advance of time in both (or, more generally, all) of the models running together dynamically.
Computing Requirements
3. The RFS model of this scenario, running alone (i.e., without the MIDAS link) in asynchronous mode with selective resynchronization, completes about 35-60 update cycles per second on a Pentium IV with 261 megabytes of random access memory (261 MB of RAM). Consequently, a simulation of a single aircraft transiting the sector and encountering CAT runs in 12 seconds of real time; a 12-aircraft simulation, which covers approximately one hour of simulated time in the sector, runs in two to three minutes real time; and a 40-aircraft simulation, covering about two hours of simulated time and including CAT encounters, runs in about 10.5 minutes.
4. With RFS and MIDAS linked and running together, simulation of a single aircraft requires about 35 seconds of real time and 19 MB of RAM for the 15 minutes of simulated time to transit the subject sector. This is about three times longer than the single-aircraft case with RFS running without MIDAS. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：DEVELOPMENT OF FAST-TIME SIMULATION TECHNIQUES(37)
