2007-06-25
Possible replies in condensed format.
Other well motivated replies, not listed below, have also been given points. The open questions give room for interpretation and this I have tried to account for.
I decided to include the 30% weight factor for the project exclusively for those cases where it improves the individual result. In other words, the project grading will never decrease the individual grading.
Home Examination, May 2007
MMF320 - Active safety
1) Research and development of new safety systems always require background data regarding real world accidents. In crash-safety, a lot of research has been carried out to study crash events to learn more about e.g. vehicle deformation, occupant loading and injury outcome.
What type of research is needed to give a good background to develop active safety systems that aim at avoiding or mitigating accidents?
Describe shortly, methods and types of equipment that are commonly used in this research field. Which are the strengths and weaknesses of the methods and the various types of equipment?
Causes leading to the accident need to be understood in order define the needs and the desired functions of the active safety systems.(1p)
Examples of methods: (description 0,5p; strengts and limits 0,5 p)
- In depth investigation of contributing factors using interviews etc, e.g. DREAM (gives a full coverage of background information as perceived by the driver combined with various objective data)
- Instrumented vehicles, e.g. Field operational testing or instrumented roads, e.g. camera monitored intersections. (Real life, does however not allow provocation, no repeatability)
- Test track (rather controlled, allows some level of danger and is still done in a real vehicle with real dynamic response)
- Simulator set-ups (precise conditions, repeatability)
2) Give a short overview of different sensor types that collect information about the vehicle surrounding(excluding systems that rely on information exchange with surrounding information sources). What are the relative advantages and disadvantages of such frontal systems in terms of performance? Give examples of how several sensor types can be combined and what improvements these combinations offer.
E.g.
Cameras
Radars
Laser radars
Differences in lateral or longitudinal precision, sensitivity to undesired signals such as irrelevant radar reflexions. (3)
Sensor fusion e.g. radar and camera, taking the best from the two technologies. (2)
3) Some of these frontal sensor systems are part of automatic collision avoidance or collision mitigation systems. Describe two basic types of intervention that are available in collision avoidance.
Describe a few potential problems/dangers with automatic systems. Describe how some car manufacturers design their systems to minimise these potential problems.
E.g. braking and steering (2p, if including a brief system description)
E.g. too high reliance or adaption from the driver. False activation due to sensor system failure or incompleteness. Legal responsibility problems if the automatic intervention causes dangerous situations (1p)
Manufacturers may allow action only if the driver is attempting to react on the upcoming danger, or allowing the driver to override the system action. (2p)This is also a way to avoid legal responsibility issues and driver acceptance since it leaves the driver in control.
4) Give a quantified example of how a collision mitigation system can reduce the impact speed and injury risk.
E.g. the quantified example included in Yngve Håland’s lecture presentation or similar.
5) Give examples of how the crash protection can be improved in a vehicle using various types of pre crash sensor information. Discuss advantages and potential side effects of reversible crash safety systems.
E.g.:
- Safety system(e.g. Air bag) optimization regarding occupant size, seated posture.
- Crash severity and crash initiation prediction for safety system optimisation.
- Pre-crash deployment with less aggressive and more optimised function, or occupant posture re-configuration.
3p
E.g.
+ Reversible systems can be deployed based on less accurate pre crash information.
- False triggering can lead to driver distraction.
2p
6) Describe and discuss shortly how modern sensor and communication technologies can be used in a post-crash situation. What types of information can be obtained and transferred to the rescue service. Give examples of different types of communication technologies etc. Do you see problems for the individual car manufacturer to design and implement such systems? Are there any parallel developments that will help the implementation?
Alert rescue centre. Give position, number of occupants and crash severity. Also voice and internal camera information are possible. 2p
Mobile telephone (e.g. GSM or satellite phone) GPS navigation etc. 1p
The post crash alerting requires communication standards that may be problematic to establish. On the other hand, currently proposed systems can take advantage of recently established standards (GSM, GPS etc.). 2p
7) Give an overview of different available speed adaptation systems. Give examples of different levels/degrees of intervention and how effective they are. Discuss also the public acceptance and additional incentives such as economic incentives to improve the efficiency.
E.g. GPS based or transponder based information. 1p
Levels: 1p
•informative
•warning
•intervening
•overtaking
Drivers tend to adapt to the system and disregard warnings. Stronger intervention is possible but less acceptable by many drivers. The drivers attitude and subjective norm has a huge influence and may need to be addressed. 2p
Other incentives, e.g. automated economic penalties may have a more durable effect. 1p
8) Describe different system types that address driver drowsiness, directly detecting, warning or intervening, or else mitigating the collision risk. Discuss acceptance, possible dangers
Driver surveillance, e.g. camera based, using image processing. 1p
Vehicle motion surveillance (e.g. monitoring steering manoeuvre pattern). 1p
Lane departure warning etc. 1p
Acceptance is good in the warning phase but stronger intervention such as stopping the vehicle is harder to get accepted and may also be risky. 1p
Driver adaptation and misuse of the system is an obvious risk. 1p
9) Discuss distraction in the modern/future car. What are the risks and possibilities with new technologies in the vehicles? What methods/systems are used in vehicles today to decrease distraction? How important is distraction as a factor in accident causation?
What methods/equipments can be used to learn more about driver distraction?
New technology, sensor systems, communication systems etc. make large amounts of information available. There is an obvious risk of information overflow for the driver. 1p
Information must be carefully selected and displayed in a way that can be easily interpreted with minimal distraction. Head up displays, information selection and timing of the display. Alternativ human senses, e.g. haptic or voice. 1p
E.g. distraction may be involved in 80% of all crashes (NHTSA) 1p
FOT may provide real life examples of distraction. Test vehicles/test tracks or simulators can be used to test the driver capacity and to what degree various types of distractions are dangerous. 2p
10) Describe the principle function of ESP systems. What type of sensor information do they typically use? Give examples of how the ESP sensor information is used also to improve the crash safety.
Individual brake power inducing a turning torque that stabilises the vehicle. Under-steer and over-steer response. Engine power reduction2p
Lateral acceleration, steering angle, wheel speed, yaw angular motion etc. 1p
ESP alert is used to trigger safety systems (typically reversible systems) pre impact. An example is the Mercedes pre-safe system that e.g. triggers a belt “retensioner”. 2p
11) Do we know anything about the risks associated with driving and drinking alcohol. What types of systems are available to detect alcohol impaired drivers? What factors will influence the chances of a general implementation of such systems in vehicles?.
Breath analyser systems descriptions. Blood analysis, accurate but less applicable in vehicles. 2p
E.g. typically 35-40% alcohol involvement according to NHTSA 1p
Companies and governmental bodies that want to make sure that their employees are sober when driving are already demanding alco-lock systems for their vehicle fleets. Responsibility questions as well as public good will are driving forces. 2p
12) Give some examples of communication systems that supply the driver with information that can reduce the risk of accidents. Are there factors that slow down, or speed up, the implementation of such systems?
GPS-maps with continuously updated traffic information. V2V communication systems, e.g. using W-Lan. V-2-Infrastructure.Dynamic road signs. 2p
Information about traffic congestions or accidents can be propagated to other vehicles in the vicinity. Automatic detection of average speed, or slippery road conditions, on certain road sections can be propagated automatically and give a good indication of the traffic density. 2p
The need for communication standards may slow down the implementation. Certain de-facto standards have however already increased the speed ofimplementation. E.g. GSM. W-lan, GPRS. 1p