- Describe an early example and more recent examples of a live simulation.
- Describe an early example and more recent examples of a virtual simulation.
- Describe an early example and more recent examples of a constructive simulation.
angles of rotation
The three critical flight dynamics parameters about a vehicle’s center of mass are known as "roll," "pitch," and "yaw." For an aircraft, roll describes the orientation of the wings, pitch describes the orientation of the fuselage up or down, and yaw describes the orientation of the fuselage left or right.
A lens on a collimator, which is a device that narrows or focuses a beam of light from a source near one of its focal points into a parallel beam.
Modeling and simulation that involves simulated people operating simulated systems. This includes human or non-human systems using behavior models in a synthetic environment. Real people stimulate (make inputs to) such simulations but are not involved in determining the outcomes.
The distance of an object or point on which you are focusing through the lens from the film plane of a camera.
Modeling and simulation involving real people operating real systems in a real environment.
Application of a standard, rigorous, structured methodology to create and validate a physical, mathematical, or otherwise logical representation of a system, entity, phenomenon, or process.
A property that causes light to be reflected very efficiently back to the light source.
Networked simulations that represent activities at a high level of realism from simulations of theaters of war to factories and manufacturing processes. These environments may be created within a single computer or a vast distributed network connected by local and wide area networks and augmented by super-realistic special effects and accurate behavioral models. They allow visualization of and immersion into the environment being simulated.
Modeling and simulation involving real people operating simulated systems in a synthetic environment. Virtual simulations inject human-in-the-loop in a central role by exercising motor control skills (e.g., flying an airplane), decision skills (e.g., firing or not firing a weapon in a combat game), or communication skills (e.g., as members of a command staff or team in a combat game).
Check Your Understanding
Recalling Prior Knowledge
In the "Categories of Simulations" lesson we were given examples of live, virtual, and constructive simulations used for training. These examples are actually fairly recent examples when you consider the history of using simulation for training. There are examples that date back before the invention of the computer. In fact, one can assume prehistoric tribes used some form of live simulation to train for the big hunt by practicing their tactics and using their weapons on a stationary or moving piece of hide (real people, real weapons, real environment). To train in reading ocean swells and waves, the early Polynesians used a Mattang Naviation Trainer, or stick chart, to represent major ocean swell patterns and the way the islands disrupted these patterns (simulated systems in a synthetic environment). Military strategists throughout history used constructive simulation or board games with dice (e.g., Kriegspiel) and large battle area maps with game pieces (simulated people) to sharpen their skills and develop tactics. Although the boundaries between these categories are sometimes unclear, the same taxonomy for classifying modeling and simulation (M&S) can be applied to these early examples.
Many people have made a difference in M&S technology throughout history. For this lesson, we will only focus on the past century. Hank Okraski and the National Center for Simulation provided much of the material in this lesson.
Pre-Computer Modeling and Simulation for Training
The history of LVC simulation for training can be traced as far back as recorded history. If we just look at the last century, we can see examples that predate the advent of the computer. For example, training pilots to fly during the First World War was expensive and dangerous. Lessons in a real plane cost $50 per hour, which was a huge sum of money then. Several flight simulators were invented to help improve training, like the French half barrel with wings, which was used to train pilots to fly the Antoinette monoplane (see Figure below). Although the earlier Wright brothers designs used levers for pitch and roll control, the Antoinette used two wheels mounted left and right of the pilot, one for pitch and one for roll. In later aircraft designs, the roll wheel was replaced with a centrally mounted control column or "stick."
The Antoinette Trainer, 1909
In the United States, not even these simple trainer devices were available. A young pilot from Binghamton, New York decided there had to be a better way to train pilots. His name was Ed Link and his father was an inventor and producer of theatre organs. In 1929, Ed Link used leftover bellows and electromechanical devices from his father to put together his first flight simulator (Figure below).
Amelia Earhart in Link trainer (rare photo), 1929.
However, the only buyers for his flight simulator were amusement parks, where they became a novelty ride. Eventually the Army Air Corps saw the need to train experienced pilots to fly by instrument during poor weather or at night. Ed Link seized the opportunity by installing a compass and a turn and bank indicator in his flight simulator that operated similar to those in real aircraft. He also added a hood to the flight simulator, which forced the pilot to only look at his instruments. By the end of 1934, Link’s flight simulators went into full production at his small plant in Binghamton, New York.
Women Accepted for Volunteer Emergency Service (WAVES) Link class, 1943.
Computer Age Modeling and Simulation for Training
The first computers used in simulations were analog computers, or differential analyzers, as they were then known. The analog computer allowed the simulation of the response of a vehicle to aerodynamic forces, as opposed to empirical duplication of their effects like the early Link trainers. Some significant developments in radio navigation, radar, and designs for synthetic radar training occurred prior to World War II at the Telecommunications Research Establishment (TRE) in the United Kingdom. A flight simulator, the Type 19 used for training in aircraft interception (AI), provided crew training for a pilot and AI operator. Using a visual projection unit and a course recorder, the computer provided the simulation of the synthetic radar picture for the AI operator of the attacking aircraft, and the relative position of the enemy target. It has been estimated the use of the Type 19 trainer saved over $78 million in aviation fuel alone.
In 1941, Commander Luis de Florez of the U.S. Navy visited the United Kingdom and wrote his "Report on British Synthetic Training," which was highly influential in establishing the Special Devices Division of the Bureau of Aeronautics, the predecessor of the present day Naval Air Warfare Center Training Systems Division (NAWCTSD) in Orlando, Florida. During this time, under the leadership of Commander de Florez, the Navy decided to build a new electronic trainer for the PBM–3 aircraft. The device was completed in 1943 by Bell Telephone Laboratories and consisted of a replica of the PBM front fuselage and cockpit, complete with controls, instrumentation, and an electronic computing device to solve the flight equations that simulated the aerodynamic characteristics of the PBM–3 aircraft. Based on this experience with using analog computers for flight simulators, the Curtis-Wright Corporation designed and developed an instrument flight simulator for the AT–6 aircraft (Figure below).
Curtis-Wright AT–6 Analogue Aircraft Simulator, 1943.
Not all simulators were being developed for military applications. Ralph Baer, a German-born American, has been credited as "the father of video games" for his development of the Brown Box and Magnavox Odyssey, the first home video game console (Figure below). The Odyssey used a removable printed circuit board card that inserts into a slot similar to a cartridge slot that allowed you to play different games. The system was sold with translucent plastic overlays that gamers could put on their TV screen to simulate color graphics. It was also sold with dice, poker chips, and score sheets to help keep score. The Odyssey was also designed to support an add-on peripheral, the first ever commercial video "light gun," called the Shooting Gallery. Unfortunately, the Odyssey was hurt by poor marketing by Magnavox retail stores; many consumers believed the Odyssey would only work on Magnavox televisions. For that reason, Atari "Pong" games became more popular: Atari put an explanation on the box saying, “Works on any television set, black and white or color.”
Ralph Baer with 1951 Brown Box prototype video game.
Simulator displays were very limited using analog computing. To provide more realism, early flight simulator visual systems used a physical terrain model, normally called a "model board" (Figure below). The model board was illuminated to avoid shadows, and a camera was moved over the model terrain in accordance with the simulated aircraft’s movement. The resulting video was provided to the pilot using television screens in front of the replica cockpit to display the simulated outside world.
Camera Model Board System, 1959.
Unfortunately, the focal distance of these displays ended up being the distance of the television screen from the crew. For aircraft, objects in the real outside world visual scene are at a more distant focus, close to the horizon or effectively at infinity. With the advent of digital computers in the 1960s, not only did flight simulators become more reliable and easier to maintain, but they also allowed for the development of more realistic visual systems. In 1972, the Singer-Link company developed a distant focus display using a collimating lens that had a curved mirror and a beam splitter device. The focal distance seen by the user was set by the amount of vertical curvature of the mirror. The first image generation systems for simulation were produced by the General Electric Company for the space program. Special purpose computers were developed for displaying computer generated graphics in three dimensions; no camera model board was required. Two professors in the University of Utah's department of computer science, David Evans and Ivan Sutherland, were pioneers in computer graphics technology (Figure below). They formed a company and, in the 1970s, formed a partnership with Rediffusion Simulation, a United Kingdom-based flight simulator company. During the next three decades, they developed display systems with enough brightness to light up a simulator cockpit to daytime light levels.
Dave Evans and Ivan Sutherland with LDS1, 1969.
In the 1970s, Navy research engineer Al Marshal used a laser transmitter and receiver mounted on a rifle to simulate direct fire at a target on a retroreflective screen. When the light energy from the laser reflected back to the receiver, information would be encoded about whether or not one hit the target. He also put the receiver on a man-worn vest, creating the world’s first laser tag system and the predecessor to the modern day Multiple Integrated Laser Engagement System (MILES) (Figure below).
Navy Research Engineer Al Marshal with the first laser tag simulator.
In the 1980s, the Defense Advanced Research Projects Agency (DARPA) began developing a wide area multi-user simulation network called SIMNET. SIMNET was designed to allow several hundred trainers (e.g., tanks, shown in Figure below, and aircraft, shown in Figure below) to represent their location, movement, and health (damaged or not) in a shared simulated environment. The fidelity of SIMNET was such that it was used to train for mission scenarios and tactical rehearsals for operations performed in U.S. actions in Desert Storm in 1991. SIMNET is the predecessor of the current high level architecture (HLA) and run-time infrastructure (RTI) used for distributed real-time computer simulation systems.
Tank simulator (gunner’s position) and view of the synthetic environment.
Jet aircraft simulator and view of synthetic environment.
In the early 1990s, the Navy began developing a head mounted display (HMD) based system called Virtual Environment for Submarine Ship Handling and Piloting Training (VESUB) (below). This design took advantage of computer hardware and software advances to form a virtual reality (VR) training medium, often called a virtual environment (VE). A head tracking device provides user head movement data to an image generator, constantly providing a simulated 360 degree representation of the visual environment to the user, complete with accurate cultural features (e.g., navigation markers and landmarks) and varying environmental conditions (e.g., fog or rain). This advanced trainer provided inexpensive but detailed harbor and channel ship handling training for a submarine officer of the deck (OOD).
VESUB trainer, 1990s.
Recent Developments in Modeling and Simulation for Training
The Virtual Reality Education for Assisted Learning (VREAL) is an innovative educational program for the deaf and hard of hearing (Figure below). VR was chosen as the delivery medium to teach both living skills and academics. Research shows that humans can process visual information 60,000 times faster than textual information. Also, VR is highly interactive and provides more motivation to students.
A safe and effective transportation network in a city is vital to both the safety of the city’s commuters and its economic vitality. Public transit is an important part of the transportation system. Transportation modeling and simulation (see Figure below) allow city planners to train and make informed decisions regarding road expansions or public transit.
Transportation Management Simulation.
Oil spills from deep ocean oil wells can threaten our economy and the environment. Mathematical three-dimensional models have been developed to simulate rate and transport of oil spilled in the ocean (Figure below). These models are capable of simulating both surface spills as well as deep-water oil jets. They can be used as valuable training and planning tools for emergency managers.
Clarkson University Deep Oil Well Spill Model.
Damage to structures, whether caused by human action or by nature, needs to be analyzed. Structural engineers need to know from a scientific perspective what happened to the buildings during damaging events in order to prevent future failures. State-of-the-art animated visualizations from models can help provide training and answers to questions (Figure below).
Purdue University 9/11 Simulation.
Integrated medical simulation capabilities provide valuable training to combat medical and non-medical personnel and civilian first responders (Figure below).
Military and Civilian (First Responder) Human Patient Simulators.
Commercial aircraft simulators helped in development of entertainment simulations, giving audiences a chance to see and feel the thrill of the chillingly real and the utterly fantastic (Figure below).
The Wizarding World of Harry Potter 3-Axis Simulator.
- LVC modeling and simulation existed before the advent of the computer. Although simple or crude, simulation provided valuable and safe training short of learning on the job.
- With the advent of the digital computer, LVC modeling and simulation became more advanced, affordable, and realistic. This made use of simulations for training invaluable.
- Modeling and simulation can be used for high fidelity planning, analysis, training, and entertainment.
- What did the first aircraft simulators look like?
- What flight simulator was the first to use an analogue computer?
- Describe, at a high level, how a HMD works?
Further Reading / Supplemental Links
Points to Consider
Modeling and simulation has been used for training in many forms throughout history.
- What was the earliest and least complex form of simulation?
- What was the first attempt to provide a wide area multi-user simulation network?
- What is the most recent and very complex form of a simulation?