STONE SOUP SIMULATOR
INTRODUCTION
A key goal of the Aviation Operations Branch (AFO) at NASA Ames is
to investigate the effect of new automation and communication interfaces on Air
Traffic Control (ATC) and commercial flight deck personnel. This human-machine
systems research is sponsored through NASA and FAA research initiatives
including Aviation Safety and Automation (AS/A), Terminal Area Productivity
(TAP), and High Speed Research (HSR). One aspect of this research is the
investigation of advanced prototypes and concepts, which requires flexible and
rapidly reconfigurable simulation capabilities.
A part-task simulator that provides this functionality has been developed
within the FLT branch. This system provides separate flight and ATC simulator
stations, party line vocal and datalink communications, and audio/video
monitoring and recording capabilities. Over the last two years, and at various
stages of development, it has been used to investigate human factors research
issues involving: communication modality; message
content and length; message formatting ; and the graphical versus textual
presentation of information.
Facilities
The Part-Task simulation laboratory is located at the Flight Human Factors
Branch at the NASA Ames Research Center in Moffett Field, CA. It consists of
individual, reconfigurable rooms for flight deck, ATC, and experiment
monitoring activities. The flight deck and ATC rooms are both sound-proofed
and measure 8' x 8' each. The experiment monitoring activity occupies a 10'
x 12' area and is partially enclosed. This room also serves as a video review
area for post-experiment analysis.
Each room is equipped with wall and subfloor interconnects for computer
networking, radio voice communications, and audio/video monitoring and
recording. These interconnects allow the system to be customized to meet the
specific requirements of each study. Figure 1. illustrates the physical layout
of the laboratory along with the location of major facilities for an upcoming
experiment.
Figure 1. Physical Layout of Part-Task Laboratory.
System Architecture
Three Silicon Graphics XZ4000 Indigo workstations provide the computing power
for the part-task laboratory. Each is configured with 64Mbs of RAM and a 1Gb.
disk. These systems communicate via their own local ethernet subnet that can
be isolated from the building network during simulations. Off-line development
is provided by two similarly configured Indigo2 XL workstations. Figure 1.
shows the current configuration of the lab with two of the workstations
assigned to the flight deck and the third assigned to the ATC task.
All part-task software is developed in C, with FORTRAN used only when
necessary to support already developed routines. The software architecture
uses a communicating process, client/server methodology, which is supported
using UNIX sockets. This architecture allows the processes to be distributed
among the computers so that graphical and computational loads can be equalized
for each system.
Flight Interface
Flight simulation capabilities are provided by an FLT rehost of the
Crew-Vehicle Simulation Research Facility's (CVSRF) Advanced Concepts Flight
Simulator (ACFS) software to the Indigo workstation.
This system provides a full glass cockpit interface consisting of primary
flight instruments along with secondary synoptic displays as illustrated in
Figure 2. The 747-400-style flight instruments include a primary flight (PFD)
and weather-enhanced navigation display. The paged synoptic display provides
access to various aircraft systems and a prototype datalink interface. The
standardized architecture of the secondary display software allows new
synoptics to be developed and integrated with a reduced amount of effort.
Figure 2. Primary and Secondary Flight Displays.
The flight simulator includes realistic aerodynamics and autoflight controls
through a software based Mode Control Panel (MCP) and Flight Management System
(FMS)/Control Display Unit (CDU). The FMS interface provides capabilities
similar to a Boeing 757-class aircraft. The MCP resides on the main flight
deck monitor (figure 2.), and the CDU is displayed on right side of the
alternate monitor as illustrated in figure 3. The "soft" nature of the CDU and
MCP interfaces have allowed many innovative automation concepts to be pursued
that would be difficult to implement in a traditional full-mission simulator.
Aircraft performance and flight handling characteristics of the simulator are
representative of a Boeing 757-class aircraft. While takeoff and landing
capabilities exist, these phases are typically excluded from part-task
scenarios. No "out the window" views are currently provided.
Figure 3. Secondary Task and CDU Displays.
Pilots interact with this system via mouse input and/or a BG-systems 3 degree
of freedom joystick with integral button/lever box. This box allows the
control of flaps and speedbrakes and also permits the use of alternative
joysticks via an external interface. Direct manipulation of the flight
interface will soon be available with the integration of Elotouch Systems'
touch screen displays.
ATC
Monitoring and control of the aircraft through the airspace environment is
accomplished through an ATC control/display simulator. This system is an
enhancement of software originally developed by ARGO Systems for the CVSRF. It
offers functionality beyond standard ATC displays including multiple resolution
and repositioning capabilities. A secondary window is provided as a datalink
message interface (see figure 4.).
Available airspace environments include Greater New York City and the San
Francisco Bay Area to Los Angeles flight corridor. All major airports and
NAVAIDs are defined with multiple ILS approaches provided at terminal airports.
Enhancements to these as well as the development of new environments are
provided as needed to support experiment requirements.
Figure 4. ATC Display.
Datalink
The Datalink communications system is an enhancement of full mission developed
code with advanced capabilities for modification and format manipulation. The
aircraft interface provides message accept, reject, and clear commands along
with autoload capabilities into the MCP and/or CDU. Message log and review
facilities are provided. A prototype interactive graphical datalink interface
that can display steering commands on the PFD has also been developed. The ATC
Datalink interface allows textual clearance and informational messages to be
sent and monitored. Messages can be developed in advance and issued using
keyboard commands or created on-the-fly as free text messages.
Secondary Task
The flight deck simulator provides the capability of measuring the difficulty
of automation and communication tasks (such as datalink communication or CDU
programming) by evaluating a pilot's performance at a concurrently performed
"secondary" task. High performance at the secondary task indicates spare
pilot attention capacity for the primary task. An earlier version of the
secondary task involved monitoring a gauge for an out of range level. The
data recorded for this discrete task included response time and error rates.
A continuous compensatory tracking task has been developed as the secondary
task for an upcoming experiment. This task requires a pilot to use a joystick
to maintain a cursor within a target area while a forcing function of random
sine wave inputs attempts to drive it out. That target area is illustrated as
the left side of figure 3. The deviation of the cursor from the center is
collected as the tracking error, (secondary measurement).
The secondary task is integrated into the flight simulator with respect to
UNIX process scheduling and data collection. This allows the secondary task
to be run or tested independent of the flight simulator. A software framework
for the secondary task has also been established, so that newly developed tasks
can easily be substituted for the current instance.
Audio Communications
Verbal communication between the pilot and ATC is provided via a partyline
communications interface. This system spans both rooms, supporting the
monitoring and stereo (pilot/ATC) audio recording of verbal interactions for
future review. Push To Talk (PTT) capability is provided to both the Pilot and
ATC specialists.
To support the reproducibility between experimental runs and among
controllers, the ATC specialist's voice commands can be digitized in advance
and saved to disk using the Audio Interchange File Format (AIFF). These
messages can be dispatched by the controller using keyboard commands at the
appropriate time during the simulation. The computer outputs the message into
the partyline as if it were spoken by the controller.
Data Collection
Data collected from the simulation is programmable and are written to disk as
time, variable name, and value triplets. Both discrete and continuous
variables are collected; examples include: FMC/CDU button presses, aircraft
state data, and secondary task performance. Data collection is integrated into
the process scheduler on a single computer, ensuring a consistent time
reference.
Audio/Video Monitoring and Recording
The ability to monitor the actions and progress of the simulation subject is
provided via the partyline audio and several color video inputs. A Super-VHS
camera can be statically positioned within the subject room to collect physical
movements and the overall flow of the experiment. Subject focus and exact
manipulation of the interface can be collected via the direct output of the
subject monitors (displays, changes, and mouse position). This capability is
provided by Silicon Graphics' Gallileo video output hardware.
Figure 5. Part-Task Video Schematic.
This video can be routed to twin Super-VHS Video Cassette Recorders. The
output from the audio communication system can be split and recorded to each of
four available audio tracks. Time and subject information can be added to the
tape via a programmable Evertz timecode generator. Figure 5 shows the video
schematic for an upcoming experiment.
FUTURE DIRECTIONS
Future development of the part-task lab will be driven largely by NASA flight
deck research requirements associated with the TAP and HSR research
initiatives. The goal is to continue to develop the base capabilities of the
simulator with specialization performed as needed to support specific studies.
Experiments planned for the near future include: an analysis of datalink
message manipulation and negotiation interfaces, an investigation of pilot
decision making using a new diagnostic interface, and a study of how pilot
decision methodology is effected by time and informational constraints.
Enhancements to the flight deck systems will include a second pilot station to
support crew interaction studies and the integration of additional aircraft
systems, including "soft" representations of essential flight controls such as
autothrottles, flaps, and speed brakes. Further development of the ATC
environment will include the rehost of a version of the Center TRACON Advisory
System (CTAS) and a pseudo-pilot station to provide
realistic background traffic and communications. Improvements to the
simulation infrastructure will include dedicated high-speed network
capabilities, the development of real-time data monitoring facilities, and the
incorporation of a low-cost, flexible cockpit mockup.
ADDITIONAL INFORMATION
Pisanich, G., Lee, E., Beck, L. (1994).
A Part-Task Simulator for
Automation and Communication Research AIAA Conference on
Flight Simulation Technologies, Scottsdale, AZ.
Point of Contact: Dr. Kevin Corker
or Greg Pisanich