Simulators and Test Tracks Flashcards
How many variables of interest are in experiments at minimum?
2
What do researchers want to discover from conducting experiments?
How ___ affects the outcome:
- predictor variable
- varying levels of the predictor variable
What is the predictor?
The independent variable
What is the outcome?
The dependent variable
What is an example of a predictor in a driver reaction time study?
Level of uncertainty to lead vehicle brake lights:
- hill
- curve
- straight, flat road
What is an example of an outcome in a driver reaction time study?
driver reaction time
What are control variables?
Factors that could affect the dependent measure, but for various reasons their level is held constant
What are some examples of control variables?
- testing only male drivers
- testing during dry, daylight conditions only
What is an intervening variable?
Variable that intervenes between the independent and dependent variable
What is an example of an intervening variable?
In a brake reaction time study, driver expectancy intervenes between the independent variable and the dependent variable.
Describe confounding variables.
- Not manipulated or controlled in the study
- Less of a factor in the experimental studies but can still play a role
What are some examples of confounding variables?
- weather
- time of day
- trip length
Describe moderating variables.
These variables attenuate the effects of the independent variable on the dependent variable by exerting influence or moderating behavior
What are some examples of moderating variables?
- sleep hygiene
- personality characteristics
- vehicle make/model
How are control variables, intervening variables, confounding variables, and moderating variables related to independent and dependent variables?
What is the strength of controlled experiments?
Causation
What are some pros of controlled experiments?
- can determine causation
- easy to study the effect of predictor(s) on driving outcomes while controlling for several confounding variables
- Can clearly determine whether certain predictors cause specific driver behavior outcomes
- Can determine if specific technology (e.g. infotainment systems) affects driving behavior
How do infotainment systems affect driving behavior?
- eyes-off-road time
- red light reaction times
- lead vehicle brake light reaction times
What is one limitation of controlled experiements?
- Unsure whether they will translate into real world
- the driving environment is already constrained in many ways
Describe fixed-base driving simulators.
- Driver and vehicle are stationary
- Scene moves on the display in front of driver
- Driver provides steering, accelerator, and braking input using controls and this will impact visual scene
- Scene can be 360 degrees or 30 degrees in front of participant
- Some controls are keyboard/joystick or steering wheel/foot pedals
- Visual scene can range from cartoonish to fairly realistic
What are pros of fixed-base driving simulators?
- Simulators are excellent for testing driver response to a specific situation
- especially a dangerous situation
- Simulators are also excellent part-task trainers
What is a famous example of a Motion-Based Simulator?
the National Advanced Driving Simulator located at the University of Iowa
Describe motion-based driving simulators.
Visual scene moves but there are additional cues of actual motion.
This includes:
- pitch
- proprioceptive stimulation when we drive around a curve
- vibrations of the roadway
Describe the National Advanced Driving Similator.
- Movable 24’ diameter dome
- Full size vehicle test buck
- 360 degree visual scene
- 15 computer synchronized projectors
- Various roadways, traffic conditions, weather, and lighting
What makes the National Advanced Driving Simulator unique?
It is the world’s highest fidelity simulator (meaning a high degree of exactness in reproduction)
What can the National Advanced Driving Simulator measure?
- Driver behavior
- Eye movements
- Speed
- Lane-keeping
What are some cons of the National Advanced Driving Simulator?
Very expensive:
- to purchase equipment
- to maintain and keep running
How can a driver’s sense of speed in driving simulators be assessed?
By obscuring the speedometer and:
- Asking drivers to accelerate to certain speed and hold that speed.
- Actual speed would be recorded.
- Asking drivers to accelerate until experimenter told them to hold the speed. Once holding speed steady, experimenter would ask driver how fast the vehicle was traveling.
How does simulated speed compare to real speed in driving simulators?
Simulated speed appears lower than real speed by 10-20 km/hr
Are estimated on-road speed and in-simulator speed related?
Shinar & Ronen (2007) found a strong linear relationship
Can driving simulators yield valid results?
Yes, generally
Describe brake-steering reaction time studies.
- Participants encountered an unexpected vehicle that entered their path as they approached an intersection
- Advanced, motion-based simulator
How did in-simulator average steering reaction times compare to on-road?
Average steering reaction times:
- in-simulator: 1.64 seconds
- on-road: 1.67 seconds
How did in-simulator average braking reaction times compare to on-road?
Average brake reaction times:
- in-simulator: 2.2 seconds
- on-road: 2.3 seconds
Which four different driving simulators across the U.S. did Lee et al. (2013) compare?
- National Advanced Driving Simulator
- Fixed-based simulator with 3 degrees of movement and a 240-degree field of view
- Fixed-base simulator without any movement an similar FOV
- Mini-NADS that is fixed based with three small front screens for 132 degrees field of view
Describe the Lee et al. (2013) four simulator study.
Different participants drove in the same roadway conditions in each simulator and experienced similar traffic conditions and scenarios.
Describe the results of the Lee et al. (2013) four simulator study.
- Good relative fidelity for speed
- Similar perceptions of “overall feel and similarity to driving”
- Similar levels of simulator sickness for all four driving simulators (~10% of population)
What is the primary objective of simulator studies?
To predict the on-road performance from simulator data
What indicates that simulator data is a good measure for predicting on-road performance?
we continue to see mathematical, linear relationships between driving performance in-simulator and on-road
What are some pros of simulators?
- Less expensive to build “new roads” in simulators
- Different roadway geometries can be tested in simulators
- Crash scenarios can also be safely tested in driving simulators
What did Jamson, Lai, and Jamson (2010) test in driving simulators?
20 different speed abatement techniques
What are some examples of abatement techniques Jamson, Lai, and Jamson (2010) evaluated in driving simulators?
- peripheral hatchings of lane markers
- rumble strips
- vehicle-activated electronic speed signs
- speed limit signs
What are some limitations of driving simulators?
- Participants know that they can not get into a crash
- Simulator sickness (must be accounted for and controlled)
- Contrived situations (are not necessarily representative of what a driver would do in real-world environments)
- E.g. may not choose to text and drive when experimenter instructs them
Describe on-road experimental studies.
- Some manipulation of the situation is occurring
- Differences in driving performance are measured
What are three examples of on-road studies?
- Test track
- Public Roadways
- with in-vehicle experimenter providing instructions
- without in-vehicle experimenter
What are the conditions on public roadways?
- Set route
- Typically set times of day (to match traffic conditions)
- Typically clear, dry conditions
What is the objective on on-road studies?
Test new in-vehicle technologies to assess how drivers will interact with, use, and/or respond in a real-world driving environment
What are some techniques to systematically test in the real world (on-road studies)?
- GPS geofences
- Testing at similar times of day/day of week
- Cameras/sensors on vehicle
What is the purpose of geo-fences in on-road studies?
to present alerts to drivers at precise locations regardless of speed
What is the purpose of testing at similar times of day/day of week?
to keep traffic patterns similar
What is the purpose of instrumenting vehicles with cameras/sensors for on-road studies?
to detect other traffic so as to alert in similar traffic situations
What are some examples of variables that can be evaluated with on-road studies?
- infotainment systems
- communication devices
- roadway signs
- roadway furniture
- roadway geometries
Describe the pros of Augmented Reality/Virtual Reality.
- Can provide an interesting hybrid of driving-simulator and real-world environment in a controlled environment
- e.g. AR in a vehicle on a test track
- Present a wide variety of different traffic environments and scenarios as well as driver displays
- Can test driving performance with AR displays on a test track to assess driving performance prior to testing on public roadways
What are some limitations of Augmented Reality/Virtual Reality?
- Vehicle environments are difficult and complex.
- Much testing will need to be conducted to ensure safety.
What are some pros of on-road studies?
- Middle ground between complete experimental control and drivers who are navigating the world with their own pressures/goals.
- Some level of experimental controls to assess driving performance on actual roadways
- Participants are on real-roadways with real consequences so driving performance does not need to be further validated
- Important step prior to a field operational test to ensure that FOT participants will remain safe
- No simulator sickness
What are some limitations of on-road studies?
- Scenarios are contrived
- Participants are not under their personal normal, daily pressures
- e.g. May still not choose to text and drive when experimenter instructs them
- Because there are real consequences, there is also the danger of participants/experimenters getting hurt and/or injured
- IRB is important for these studies
- Conflict-like scenarios must be carefully choreographed to be as realistic to participant with no real danger present.
- Cannot actually have crash scenario but can be very realistic
