Human-in-the-Loop is defined as a model that requires human interaction. HITL is associated with Virtual Modeling & Simulation (M&S) in the Live, Virtual, and Constructive

Live, virtual, and constructive

Live, Virtual, and Constructive Simulation is a broadly used taxonomy for classifying Models and Simulation . However, categorizing a simulation as a live, virtual, or constructive environment is problematic since there is no clear division between these categories...

 taxonomy

Taxonomy

Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...

. HITL models may conform to Human factors

Human factors

Human factors science or human factors technologies is a multidisciplinary field incorporating contributions from psychology, engineering, industrial design, statistics, operations research and anthropometry...

 requirements as is the case of a Mockup

Mockup

In manufacturing and design, a mockup, or mock-up, is a scale or full-size model of a design or device, used for teaching, demonstration, design evaluation, promotion, and other purposes...

. In this type of simulation a human is always part of the simulation and consequently influences the outcome in such a way that is difficult if not impossible to reproduce exactly. HITL also readily allows for the identification of problems and requirements that may not be easily identified by other means of simulation.

HITL is often referred to as interactive simulation which is a special kind of physical simulation in which physical simulations include human operators, such as in a Flight simulator

Flight simulator

A flight simulator is a device that artificially re-creates aircraft flight and various aspects of the flight environment. This includes the equations that govern how aircraft fly, how they react to applications of their controls and other aircraft systems, and how they react to the external...

 or a driving simulator

Driving simulator

Driving simulators are used for entertainment as well as in training of driver's education courses taught in educational institutions and private businesses...

.

Benefits

Human-in-the-Loop lends itself the ability for the user to change the outcome of an event or process. HITL is extremely effective for the purposes of training because it allows the trainee to immerse themselves in the event or process. The immersion effectively contributes to a positive transfer of skills acquired to the real world. This can be demonstrated by trainees utilizing flight simulators in preparation to become pilots.

HITL also allows for the acquisition of knowledge in regards to how a new process may impact a particular event. Utilizing HITL allows participants to interact with realistic models and attempt to perform as they would in an actual scenario. HITL simulations bring to the surface issues that would not otherwise be apparent until after a new process has been deployed. A real world example of HITL simulation as an evaluation tool is the Federal Aviation Administration’s (FAA) use of HITL simulation to allow air traffic controllers to test new automation procedures by allowing controllers to direct the activities of simulated air traffic while monitoring the impact the newly implemented procedures.

With almost any process there always remains the human element which can only be reproduced using HITL simulation. Although much of can be done to automate systems humans typically still need to take the information provided by a system to determine the next course of action based on their judgment and experience. Intelligent systems can only go so far in certain circumstances to automate a process, only real humans in the simulation can accurately judge the final design. Table top simulation may be useful in the very early stages of project development for the purpose of collecting data to set broad parameters, but the important decisions require human-in-the-loop simulation.

Human-in-the-Loop Simulation within Virtual Simulation Taxonomy

Virtual simulations inject Human-in-the-Loop in a central role by exercising motor control

Motor control

Motor control are information processing related activities carried out by the central nervous system that organize the musculoskeletal system to create coordinated movements and skilled actions...

 skills (i.e., flying an airplane), decision making

Decision making

Decision making can be regarded as the mental processes resulting in the selection of a course of action among several alternative scenarios. Every decision making process produces a final choice. The output can be an action or an opinion of choice.- Overview :Human performance in decision terms...

 skills (i.e., committing fire control resources to action), or communication skills (i.e., as members of a C4I team).

Examples of Human-in-the-Loop Simulators

• Flight Simulators
• Driving Simulators
• Marine Simulators
• Select Computer & Video Games

Misconceptions

Although human-in-the-loop simulation can include a computer simulation in the form of a synthetic environment, computer simulation is not always a form of human-in-the-loop simulation, often this type of simulation is considered human-out-of-the loop simulation. In this particular case a computer model’s behavior is modified according to a set of initial parameters. The results of the model differ from a true human-in-the-loop simulation because the results can easily be replicated time and time again by simply providing identical parameters.