Tentor Flashcards

Question

The Society of Automotive Engineers proposes 6 mutually exclusive levels of automation. a. Explain Level 3 from the SAE level of automation, more specifically (1 point) i. Are both lateral and longitudinal control automated? ii. Is the driver supposed to monitor the system during Level 3 automation? iii. Who is responsible for potential fallbacks?

Answer 1

i. yes ii. yes iii. The driver

Answer 2

The ODD defined in which condition the system is supposed to provide automation. For level 4 the ODD is still limited, for level 5 the ODD is not limited.

Answer 3

a. The first figures shows how development and evaluation are part of a continuous process, where evaluation inform development, and development improves safety systems, thus creating new opportunities/needs for evaluation. The second figures shows how both development and evaluation happen in steps. From a system to a component level for design and from component to system level for evaluation. Although design happens before evaluation, different steps in design correspond to different steps in evaluation. b. A use case is a (visual) description of the intended use/application of a system. c. In a car following scenario a target vehicle moves at 30 m/s and brake harshly (-6 m/s2), the ego vehicle follows at an equal speed at a distance of 100 m, time to collision goes eventually below 1.5 and a FCW warning is activated.

Answer 4

a, b, c, d a. horizontal: 400 pixels and vertical: 300 pixels => true b. DistToObject = k * ImageWidthPixels/ObjPixWidth 4 = k * 300/100 => k = 4/3 x = (4/3) * 300 / 20 = 20m => true c. width: 4 = k * 400 / 200 => k = 2 => 2 = 2 * 400 / x => x = 400 height: 2 = (4/3) * 300 / x => x = 200 Size in camere frame = 400x200 pixels => true d. ``` 800 = (4/3) * 300 / x => x = 2 pixels 810 = (4/3) * 300 / x => x = 2.025 pixels ``` => true, cannot tell the difference

Answer 5

This question refers to the lecture: 160912 - Signals and CAN.pdf a. Speed requires 128 different values, which can be coded with 7 bits. b. Acceleration would require ~30/0.01 different values, thus 12 bits. As we still only need less than 3 bytes, yes, there is enough space in this field that can be up to 8 bytes long. ``` c. See slide 55. Any of the following error detection scheme would be a good answer if correctly explained. For explanations see (AN-1123.pdf) Error detection schemes: i. •CRC check ii. •Transmission bit verification iii. •Bit stuffing rules iv. •Fixed-form bit field checks v. •Mandatory message ACK ```

Answer 6

a. The field IDENTIFIER is a unique ID for each ECU on the CAN bus. The lower ID always wins: in other words the ECU with the lowest ID get to talk first in a possible conflict with other ECU. If more than one ECU starts transmission at the same time, they all listen to the CAN and as soon as an ECU notice that another ECU with a lower ID is transmitting, the ECU with a higher ID stops transmission. b. The DATA field is used to transmit data, signals in our case. More than one signal can find place in this field. DLC specifies the length of DATA. c. The CRC field is used to verify that no error occurred in transmission and it is calculated by all ECU listening to the CAN as new message are transmitted. When a message is transmitted with a different CRC than the one calculated on the fly by the ECU listening, an error must have occurred and the error is notified on the CAN bus. If no error is detected, there is a high chance that the frame is correct.

Answer 7

a, b, c, d

Answer 8

This question refers to Marco’s lecture: 130912 ‐ Sampling‐StatisticalProperties‐CAN. The CAN bus consist of two wires which link ECUs and sensors. The purpose of the CAN bus is to provide communication among ECUs and sensors. For instance the ECU with ACC function can use the CAN bus to communicate with the BCM and TCM. The CAN bus significantly reduce wiring. Possible status of the gear could be 1,2,3,4,5,R,N or DNRL. In the first case you would expect 3 bits (8 combinations) in the second 2 (4 combinations) may be enough. However, a discussion on potential combination to signal an error would be a merit.

Answer 9

This question refers to Marco’s lectures: 140915 - Frequency Domain and Digital Filtering and 140911- Synchronization and Statistical Properties. a) A car accelerates for then braking to a complete stop. Since the car travelled 30 mph and stopped in 2-3 s we can guess deceleration was about 5 m/s2 suggesting a relatively harsh braking manoeuvre. b) A periodic sine-wave noise is clearly visible, approx.. 1-2 Hz would be a reasonable guess. c) The diagram should clearly show that most of the spectrum is at low frequencies and a peak (almost a simple vertical line) is present at approx.. 1-2 Hz. d) This distribution should only present values between -5 and 35 mph. Bins around 15, 30 and 0 should be taller than the others as the car was travelling at these speed for a longer time.

Answer 10

This question refers to Marco’s lectures: 140915 ‐ Frequency Domain and Digital Filtering and 140911‐ Synchronization and Statistical Properties. a) m/s2, because a 5 g lateral acceleration is impossible for a normal car to experience in normal driving. b) A possible explanation could be the following. As the yaw rate and acceleration show these are small adjustments of the longitudinal trajectory. Probably the driver wants to align the car to some infrastructure as when parking close to the curb Assuming positive yaw rate value indicate turning left, there are two adjustments to the left followed by one to the right. The spiky signals probably result from hitting “something”. Going back to the parking example, these spikes may indicate that the car hit the curb. c) Yes the two signals are highly (and positively) correlated, in fact their behaviour over time is very similar, for instance when lateral acceleration increase so does yaw rate and when lateral acceleration decreases so does yaw rate. Yes it is reasonable because vehicle dynamics clearly require for lateral acceleration to depend on the vehicle rotation and specifically on the speed of such rotation which is what yaw rate measures. d) This distribution should only present values between ‐5 and 5 m/s2. Bins around 0 should be taller than the others as the car was travelling straight most of the time. Bins with positive values should be higher than bins with negative values. Below you can find a perfect solution which is not expected from the students. e) This spectrum should only present values between 0 and 5 Hz (10 Hz sample freq). Most of the spectrum should be below 2Hz and the spectrum should more or less monotonically decrease while moving toward the higher frequencies. It would be reasonable a relatively small component at 0 freq (indicating the constant value in the Fourier transform from the mean of the signal). Since the adjustments are almost periodic, one every 10 sec, a peack can be expected around 0.1 Hz. Below you can find a perfect solution which is not expected from the students.

Answer 11

Slide 35 in the lecture 150924 - Safety Indicators and Threat Assessment (Theory).pdf reports this same figure and indicate what each area means in terms of system operation. In the same lecture threat assessment and decision making are explained with reference to scientific articles. The pink area indicate where the collision can only be mitigated. In the area with the blue star the driver can still avoid the collision by either braking or steering. For the point e) both AEB and AES would be able to avoid the crash, however the AEB could only mitigate the crash in the conditions of point f (pink area).

Answer 12

a. What is task demand? Task demand is all the stuff that must be done to perform a task. To perform the task, you MUST do certain things. The task demands it. Task demand is imposed by the task and is independent of the performer. The example in the lecture notes concerns riding a bicycle. Riding demands that you: • Balance, • Pedal, • Visually scan, • Follow rules, ... b. Provide an example of driving when the task demand is relatively high. The task demand is high on a crowded road in an unfamiliar town with lots of jaywalking pedestrians on a rainy night. Provide an example of driving when the task demand is relatively low. The task demand is low on a wide freeway in full daylight, with no oncoming traffic, few others going your direction, no pedestrians, and no cops. c. What is cognitive workload? Cognitive workload is the level of effort at thinking that an individual must perform to meet task demands. More precisely, it is the subjective, individual experience of the expenditure of mental effort in response to task demand. e. Explain how cognitive workload differs from task demand. Cognitive workload is a function of both the task and the individual. The task imposes its task demand. The driver’s response to that demand - workload - is, in turn, a function of the driver’s traits and states. Traits are enduring qualities that can be modified only with practice over time. For example, skilled drivers have different traits than novice drivers. Workload varies as a function of experience. States are temporary fluctuations in psychophysiology. For example, a bad burrito can put you in a foul state. The first kiss from a new flame can put you in a blissful state. Workload varies as a function of state. In sum, the workload experienced by different people facing the same task demand varies from person to person. For the same person, it can change from place to place, time to time.

Answer 13

Please see the example on 45‐47 in the lecture 170928 ‐ Cooperative Systems.ppt

Answer 14

An LDM is a local database including information about the environment. Part of the information in the LDM is built dynamically as a vehicle travels, senses the environment, and communicates with other vehicles and the infrastructure. An LDM presents several layers where maps, other vehicles and road‐users, and other geographical information is stored. For a vehicle receiving a beacon from an ambulance, the LDM may help the application layer understand whether the ambulance will pass on the same road of the ego vehicle (and warn accordingly) or not. The LDM is part of the facility layer and supports the application layer.

Answer 15

This question refers to Marco’s lecture 160926 - Cooperative Systems.pdf a) A possible example is emergency vehicle notification; in this case, an emergency vehicle, such as an ambulance, would broadcast its position, heading, and speed to the vehicles around. These vehicles should then warn the driver if they would be likely to end up on the ambulance path. b) Dedicated short-range communication is a set of frequency reserved for cooperative applications, this is part of the physical layer enabling the 802.11p wireless data transmission. c) An LDM is a database including information about the environment and other vehicles connected in a cooperative environment. Each vehicle has a unique LDM which is continuously updated as new information becomes available from other vehicles or the infrastructure. Cooperative applications relay on the LDM for threat assessment and decision making.

Answer 16

During this lecture we looked into 7-8 different functions, any would work for this exercise. Issues about data security, ownership, and position estimation are discussed in the first lecture. Issues about errors in data transmission are addressed in the second lecture. For the emergency vehicle application. Error in transmission may make the application not useful if the message arrives corrupted (or never) to the cars that are supposed to let the emergency vehicle pass. Error in position may end up confusing drivers who do not need to pull over to let the emergency vehicle pass. Security is an issue because if somebody hacks the emergency vehicle signature, then that driver could “pretend” to be driving an emergency vehicle and demand the right of way. Ownership for this application is not an obvious hinder, nevertheless could be an issue: for instance, the driver of an ambulance could come late to the hospital and this delay could cause harm to the patient. If the delay would be caused by the driver forgetting to activate the application, depending on whether s/he owns the data or not, the data may be used in a legal trial or not.

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