0HM310 - Automotive Human Factors Flashcards
What tasks does the driver perform in a multitask environment?
- Strategic tasks
- Tactical tasks
- Control tasks
The driving task is also defined by a series of component tasks
What are strategic tasks?
Focus on the purpose of the trip and the driver’s overall goals.
Many strategic tasks happen before the drivers gets into the car
* E.g. route planning, deciding when to go
What are tactical tasks?
Focus on the choice of maneuvers and immediate goals in getting to the destination.
They include speed selection, whether to pass another vehicle, and the choice of lanes.
What is PVAL
Primary Visual Attention Lobe
tracking control tasks has 2 dimensions:
Lateral tracking: the roadway curvature
* best performance measure is the time-to-line crossing (TLC)
* average amount of time before crossing the line given the current heading and distance from the
lane edge.
Longitudinal tracking: different channels
1. Flow of motion along the roadway
2. Location or distance of hazards
3. Traffic control devices
* Performance measure: Time-to-contact (2 s rule)
* distance divided by speed difference
Control tasks of driving
The lateral task of maintaining lane position can be thought of as a second-order control task.
* With preview (the roadway ahead).
* A predictor (the heading of the vehicle).
* constrained by the roadway curvature.
The longitudinal task is a first-order tracking task of speed keeping.
* The command input coming from internal goals (e.g., travel fast, but do not lose control; do not
get a ticket for speeding)
* or, external factors (behavior of other vehicles, hazards, traffic control signals in front)
What is automation
Automation refers to situations where a machine assumes a task that is otherwise performed by a human operator
Reasons for automation?
- Impossible or hazardous tasks (e.g., special needs population)
- Difficult or unpleasant tasks (e.g., vigilant monitoring)
- Extending human capabilities (e.g., memory aids)
- Cost reduction (e.g., automated phone menus
How to represent automation?
One way of representing automation is by the amount of human information processing it replaces (Parasuraman et al. 2000)
4 stages of automation:
- Information acquisition, selection and filtering
* Detection/monitoring (e.g., oil light) - Information integration (e.g., route planning)
- Action selection and choice (e.g., collision avoidance system)
- Control and action execution (e.g., cruise control)
Levels of car automation
5
Human Factors issues pt1
- Relation Driver/User – Vehicle:
* Trust (Reliability), Control, Convenience/Usability
* (“Do I still need to do something?”), Experience,
* Acceptance of behaviour - Relation Vehicle – Environment
* Trust (Reliability), Predictability of behaviour,
* Acceptance of behaviour - Societal level
* Technology acceptance - Reliability
* System may be at fault (i.e., actually unreliable)
* Automation may be inappropriate for certain situations (e.g., cruise control while driving downhill)
* User may incorrectly set up or use the system
* Poor understanding of automation by users
* automation induced surprises - Calibration of trust in automation
* Mistrust - not related to reliability
* Distrust – related to reliability
* Overtrust/ complacency – overreliance on automation
* Detection (vigilance)
* Situation awareness
* Skill loss
Human factor issues pt2
- Workload and situation awareness
- Loss of arousal (e.g., driving at night)
- Lack of appropriate training and certification
- Loss of human cooperation
- Driving satisfaction (book: job satisfaction)
What is workload underload?
Vigilance (=waakzaamheid) and Underarousal
Sustained attention in low-arousal environments can be just as fatiguing as high-workload situations
causes of vigilance decrement
- Time: long duration increases miss rate
- Event salience: subtle events show larger
miss rate - Signal rate: infrequent events are more
effortful to monitor - Arousal level: infrequent events are less
stimulating and arousal falls- Enhanced by sleep deprivation
Vigilance remediation
- Watches should not be too long
- Frequent breaks
- Enhance salience of signals (signal enhancement)
- Alter detection criteria by providing large rewards
- Increasing signal expectancy
* Deliberately include false signals - Increase level of arousal
* Coffee
* Concurrent non-interfering tasks (music, conversation)
* Prevent sleepiness
* Movements (chewing gum)
What is bad automation
- Automates easy tasks, but makes complicated tasks more difficult
- It negatively impacts human performance (skill loss)
- It fails in difficult situations, not easy ones
- It is not either/or between human and system (function allocation)
What is Human-centred automation?
- Automation to support and complement humans
- Shared roles and responsibilities
- Keeping the human informed
* Relevant and timely information
* Keep human up-to-date as to the automated actions - Keeping the human trained
* Train for system failure - Keeping the operator in the loop
* Some level of involvement (e.g. veto) will keep human involved and appraised - Selecting appropriate stages and levels of automation when automation is imperfect
* Imperfection at higher stages more likely to be harmful - Making automation flexible and adaptive
* Dynamic automation, tailored to task demands and operator load
What is situation awareness? & how to measure it
– Perception, comprehension & future projection of elements in environment
– SAGAT questionnaire (Endsley, 1998a), RT, time-to-learn a system …
What happens at night?
- Rod vision
- loss of colour
- loss of contrast sensitivity
- Loss of spatial acuity
Visibility Issues - Signage
- Minimize visual clutter from unnecessary signs.
- Locate signs consistently.
- Visibility issues can become amplified by deficiencies in the eyesight of the viewer.
Human visual system
- Visual acuity and visual search are important for reading. Human performance mostly depends on the optics and retina of the human eye
- Spatial vision & Contrast sensitivity explains reasons for glare and night vision.
- Depth perception explains mechanisms underlying estimates of distance
Optics of the eye
- Light enters the Cornea
* strong refraction (48D) - Balance intensity/focus regulated by iris
* pupil diameter
* emotional state - Image is focused by Lens
* Accomodation - ciliary muscles change the shape of the lens - Photosensitive layer is called the Retina
The retina exists out of….?
120 Million rods
* High sensitivity (night vision)
* Rods: no colour
* Parafovea/Periphery
* Scotopic (night vision)
* very sensitive for blue/green light
* blue LEDS are blinding the rods at dusk/night !!!
* insensitive to red light
* red print will look black at dusk !!!
6 Million Cones
* Lower sensitivity (daylight vision)
* L, M and S cones: Colour vision
* Fovea
* Photopic (daylight vision)
Visual search - Saccadic eye movements
Saccadic eye movements
* Fast, jerky eye movements (up to 900 deg/s!)
* Very stereotypic velocity profile
* Brings fovea to region of interest
serial search
parallel search
Limitation of eyes
Fovea: High acuity in small (5 deg) region
* Displays that require high acuity draw attention away from Primary Visual Attention Lobe
(PVAL)
Eye movements to scan large areas with high acuity
* Search time increases with # items (serial search)
* Colour/Shape can make items pop out (parallel search)
michelson contrast (contrast sensitivity)
C = Lmax-Lmin/Lmax+Lmin
Spatial acuity is crucial for reading print
- 3 cycles/degree
- stroke width > 1/6 degree visual angle
- Maximise lightness contrast
- Avoid isoluminant colours
* black on red (red looks black at low light levels) - Avoid negative contrast
- Avoid unusual shapes, orientations etc.
Depth Cues
- Occlusion (interposition)
- Retinal Size
- Perspective
- Familiarity
- Height in picture
- Blur
- Brightness
- Colour
- Shadow
- Motion parallax
- Stereo vision (disparity)
Limitations of judging depth
- Robust; monocular and binocular
- Binocular vision not very effective beyond 5m
It is natural for the brain to combine multiple cues - Displays using multiple cues are easier to
* Detect
* Discriminate
Accommodation
* Cannot see sharp both at nearby and far distances
* Very important for display design!
* Age > 50 : eye no longer accommodates
* Bifocal or multifocal glasses
Motion on the retina can be due to:
- Object motion
- Self-motion (Eye, Head, Body)
What is optic flow
Self-motion evokes different whole-field retinal motion
patterns
* Translation (left/right)
* Expansion (forward)
* Compression (backward)
This is called optic flow
Limitations of motion detectors/optic flow and velocity perception
Motion detectors in the visual system detect motion
* Motion After Effect (MAE) when motion stops
Optic flow is the motion pattern on the retina due to self-motion
* used to extract heading information
* Used for distinguishing self-motion from object motion
Velocity perception
* Is detected directly (not derived from distance estimates)
* People adapt to high speeds
* Underestimation of velocity due to adaptation
* MAE makes it worse: for example, when leaving high-way!
What is haptics
Haptics literally determines the “feel” of the car.
Haptics is also useful for displaying information
* Haptic displays (e.g. vibrating car seat, force-feedback accelerator pedal
what is Anthropometry?
the scientific study of the measurements and proportions of the human body.
Seating: range of body postures, adequate eye position (visibility)
Reachability: controls
Designing for the “mean” is not appropriate
* provide flexible options for seating adjustment, etc
What is haptic perception?
Haptic perception is to sense an object’s properties trough touch, proprioception and
kinesthesis
* They are all part of the somatosensory system
Haptics can detect many features of objects like shape, texture, hardness, mass, weight,
temperature, etc.
Design issues:
* Touchscreens do not provide haptic feedback of keypresses
* In virtual reality it is extremely hard to provide realistic haptic feedback
* Tactile feedback can help discriminate controls
* Tactile feedback can off-load visually demanding tasks