Automotive DIL simulators range in size, complexity, capability and cost. They can be broadly classified into three basic categories:
These are primarily consumer-class simulators that are powered by gaming PCs or consoles, with relatively basic driver controls (typically a simplified steering wheel, gear selector and pedals). There are some larger, commercial systems used for amusement parks, trade shows and other events, which may feature mock-up vehicle cabins, motion systems and audio systems.
Entertainment-class graphics can be state-of-the-art in terms of quality and photo-realism. As such, it’s not unusual to see these DIL simulators being used by amateur and professional drivers who wish to practice driving on specific race tracks. However, this class of DIL simulator generally lacks the vehicle physics and environment modelling fidelity for engineering or product development work.
Human Factors DIL
These DIL simulators are designed to replicate the driving environment of a vehicle more closely and more comprehensively. They may include real or replica cabins, for instance, with fully functioning dashboards and interfaces. Outside the immediate participant surroundings, one may find large scale motion and vision hardware, similar in appearance to an aircraft simulator.
Human Factors DIL simulators are typically used for human behavioural studies rather than vehicle behavior studies, hence the name. For example, automotive manufacturers might use a Human Factors DIL simulator to study driver distraction or scenarios like low-speed city driving where accurate dynamic representation of the vehicle is not crucial.
Although some Human Factors DIL simulators feature some level of motion cueing, this is not generally a priority, aside from including some baseline movement. Likewise, the graphics technologies tend to prioritise the flexibility to modify and adapt scenarios over photo-realism or ultra-low latency.
Despite these limitations, the potential for road safety research alone can justify enormous investments in Human Factors DIL simulator installations. Some high-profile installations can take up entire rooms, and capital costs can spill into the hundreds of millions of dollars. One example is the $49 million (USD) spent to construct NHTSA’s National Advanced Driving Simulator project.
Human factors DIL simulators can play an important role for automotive manufacturers. In some cases, experiments can be conducted with Software-in-the-Loop (SIL) models or real hardware, such as engine control units, in place via Hardware-in-the-Loop (HIL). However, the limited dynamic performance of human factors DIL simulators (often compounded by the sheer scale of the hardware involved) means that they aren’t generally suitable for subjective evaluations of vehicle performance.
Engineering-class driving simulators deliver compelling driver immersion via high performance motion and vision systems, as well as comprehensive tool suites. These DIL simulators typically have medium-size form factors, and are directed towards satisfying the needs of professional drivers, vehicle evaluators and engineers.
As such, greater emphasis is placed on factors such as motion cueing, tyre and surface modelling and supplemental cueing such as steering wheel feedback. The simulators themselves are designed as lightweight machines with medium scale form factors to maximise their dynamic capabilities. In some cases, real vehicle cabin components are included to create a more immersive experience rather than for ergonomic reasons. They are also frequently connected in real-time to sophisticated vehicle sub-system models via SIL or HIL test benches.
There is often a significant overlap in capabilities; an Engineering DIL simulator can often be used as a Human Factors DIL simulator, although the opposite does not necessarily hold true. It’s also worth noting that the dynamic capabilities of an Engineering DIL simulator can often be crucial even when vehicle dynamics is not the primary focus of the experiment. For instance, a realistic sense of motion can be useful in experiments where the participant needs to experience vehicle nuances such as drivetrain development; cruise control (ACC) calibration; or handover to autonomous driving functions. Likewise, realistic haptic, vestibular and acoustic sensory cues will help to create the required immersion for other types of studies, such as NVH development.