Automotive Engineering Exam 2

Pressure Distribution on a vehicle

Figure 4.6 and 4.7

Automated Emergency Braking (AEB) systems are becoming more prevalent on new vehicles. One study by the Insurance Institute for Highway Safety (IIHS) found that the systems are not without flaw, however. What was the essence of their finding?

AEB works poorly at night

The Waymo article described the author's experiences in a Waymo taxi. How did the Waymo fares compare to those of other options for those routes? (Uber, Lyft, etc.)

About the same

What is active suspension mean in terms of damping?

Active Suspension damping is when the vehicle has hydraulic cylinders that move the suspension up and down in anticipation of bumps.

Radar adv/disadv

Adv: 1. Cheap 2. Robust 3. Short/Long range (30-250m) Reliable in weather Disadv: 1. Low resolution 2. No color

Ultrasonic adv/disadv

Adv: 1. Cost Effective 2. good @ short range Disadv: 1. Range is limited 2. Low resolution 3. No color

LiDAR adv/disadv

Adv: 1. High Resolution 2. High Speed 3. Long Range Disadv: 1. Very expensive (until now) 2. No color information 3. No established vehicle hardware (until now)

Camera adv/disadv

Advantages: 1. High Resolution 2. Color 3. Long Range Disadv: 1. Limited reliability in bad weather 2. No distance info without multiple cameras.

Contributors to drag

Forebody, Afterbody, Underbody, Skin friction, wheels and wheel wells, drip rails, window recesses, external mirrors, etc.

What are some of the types of hybrid powertrains that have been tried?

Gas-Electric, Diesel-Electric, Gas-Pneumatic, Gas-Hydraulic, Fuel Cell-Electric, and more...

According to the articles, which gender is MORE likely to trust self-driving vehicles?

Male

What is noise

Noise is the aural perception of vibration. 25-20,000 Hz. 25Hz~ lower threshold of human hearing.

What is passive suspension mean in terms of damping?

Passive suspension damping is in terms of regular shock absorbers where the damper reduces vertical acceleration from a disturbance.

What is ride?

Ride refers to tactile and visual perception of vibration. Or, classified by frequency: 0-25 Hz

When the Mercedes Drive Pilot system is engaged, the driver will be able to watch a movie, and Mercedes would be legally responsible for any crash. T or F

True

V2D

Vehicle to Device

V2I

Vehicle to Infrastructure

V2N

Vehicle to Network

V2P

Vehicle to Pedestrian

V2V Stands for

Vehicle-to-vehicle communication

Form Drag

i. Caused by pressure differential in front of/behind vehicle as viewed by the air stream. ii. Keys for reducing: continuous streamlines, avoiding flow separation.

Communication types for intervehicle communication

i. Dedicated Short Range Communication (DSRC) - wifi band, ~1000 ft ii. Cell frequencies (longer range)

Skin friction

i. Viscous drag in the boundary layer ii. Friction of the fluid (air) against the object's "skin" (auto body)

Sensor fusion

the goal of sensor fusion is that one coherent picture of what is going on around you can be made using a culmination of sensors

V2X

vehicle to everything

What does the SAE J6a standard recommend as a design limit for that same frequency?

~0.03g rms

According to ISO-2631-1978(E) standard, one might expect a human to tolerate 5 Hz of vertical vibration for one minute at what RMS acceleration levels (g's)?

~0.3g rms

Match the acronym to the correct description. You can use SAE J3016 (in "Reading" section on Moodle) or any other reference you choose. 1. LKA 2. AEB 3. ACC 4. ADAS 5. DDT

1. Lane Keeping Assistance 2. Automated Emergency Braking 3. Adaptive Cruise Control 4. Advanced Driver Assistance System 5. Dynamic Driving Task

Factors affecting Rx

1. Tire temperature (lower temp = higher Rx) 2. Tire inflation pressure/load 3. Tire material (High hysteresis bad for rolling resistance)

What are some examples of Ride Excitation Sources?

1. Tires 2. Engine 3. Wind 4. Imperfections in the road 5. Wheels 6. Open Windows

This journal article discusses driver behavior when resuming control from a highly automated vehicle. According to the abstract of this article, approximately how long does it take for a driver to regain situational awareness and resume vehicle control when the vehicle must transition from autonomous to manual operation?

15 seconds

Based on the ISO standard, to what frequency range of vertical vibration do humans seem most sensitive (most easily annoyed by)? How does this compare to humans' sensitivity to fore/aft vibrations?

4-8Hz vertical vs. 1-2Hz fore/aft. Vertical frequency sensitivity occurs at ~4x the frequency of fore/aft sensitivity.

Select all of the items below which are cited by Roger Lewis in the Washington Post as challenges to AV adoption. a. Uneven laws and insurance regulations from state to state. b. Americans like being in control c. Unmapped obstacles like potholes d. Traffic signals would have to change to accommodate AVs. e. Drivers (human or otherwise) must anticipate or guess the behavior of bikers, scooter riders, pedestrians on phones. f. It's challenging for AVs to share the roadways with unpredictable human drivers.

All except for d.

Which organization has been using the "Scout" autonomous delivery robots in trials in several areas of the country since 2019?

Amazon

NASA did some interesting work suggesting that human sensitivity as a function of frequency is dependent on the magnitude of the acceleration. What did they conclude about relatively low levels of vibration?

Discomfort is "rather independent of frequency" when the vibrations are at low amplitudes.

According to Tesla's website, how do they describe the ODD in which the "Autosteer" feature is designed to operate?

Clearly-marked lane

What does "hybrid" mean for an automobile

Has more than one source of power.

Which of the following manufacturers was the first to announce the release of a production vehicle capable of SAE Level 3 autonomy?

Honda

ITS

Intelligent Transportation System

Based on the description of the vehicle in the Waymo article, what is the SAE Level of the Waymo vehicle?

It is an SAE Level 4 vehicle. The vehicle takes care of the complete driving task, never requiring a human to take control -- but only in restricted operating areas. These vehicles are not available for sale to the public.

In the summary of the article, "Cities Are Not Ready For The Changes Self-Driving Cars Will Bring," what is the primary obstacle worried about by the author?

Jaywalking pedestrians

Standard Power Train

Look at Power point (Slide 17)

Parallel Hybrid

Look at Power point (Slide 18)

Parallel Hybrid: Common Shaft (Honda)

Look at Power point (Slide 19)

Powersplit Hybrid

Look at Power point (Slide 21)

Series Hybrid

Look at Power point (Slide 24)

"Through the Road" Hybrid

Look at Power point (Slide 25)

Automatic emergency braking

SAE Level 0

"Traffic-aware cruise control" which automatically adjusts the speed of your car to that of the surrounding traffic and maintains a safe distance between you and the car in front. The system requires you to constantly supervise this support feature.

SAE Level 1

Although the human in the driver's seat must continue to drive (be fully aware of the road situation), the driver support features provide lane centering steering and adaptive cruise control.

SAE Level 2

If you are caught in congested traffic, the car will automatically start and stop for you and steer to maintain your lane. If the system becomes confused, you will have to take over the driving tasks.

SAE Level 3

What is the SAE Level of the Mercedes Drive Pilot System?

SAE Level 3 systems will take care of the complete driving task, not requiring the driver to pay attention while the system is engaged. BUT the driver must be ready to retake control when the system determines that it can no longer do so (inclement weather, vehicle exiting its allowed operating environment, etc.).

A self-driving car that, under many conditions, will not require anything of the passengers, even if they are seated in the "driver's seat." The car will not require you to take over driving.

SAE Level 4

According to SAE J3016, an Automated Driving System (ADS) comprises the hardware and software collectively capable of performing the entire driving task on a sustained basis. This term is used to describe a driving automation system in which SAE level(s)?

SAE Levels 3,4, and 5

Directional Dependence

Sideforce can be significant. Less so on passenger cars but pronounced effects on trucks and tractor trailers. The separation region causes a pressure difference (i.e. form drag) which is why they're so easily blown over.

Ride is really hard to judge/standardize due to seating position of passengers. What does that exactly mean?

Since ride is a subjective perception, the seating position of each rider will have a different view of the ride. Also, imagine the difference in seating in a cargo van vs. a Miata (Mazda). Both will experience very different levels of ride.

Select ALL of the following which describe the operating environment in which Mercedes intends its Drive Pilot system to take care of driving tasks. a. Speeds below 40 mph b. On select highways c. On all highways d. Full autonomy in any driving environment e. Only on city streets <35 mph f. No stoplights or other traffic control systems present

a, b, and f

Mechanisms of Rolling Resistance

a. Energy loss due to sidewall deflection b. Energy loss due to tread element deflection c. Scrubbing in the contact patch d. Trie slip in longitudinal and lateral directions e. Road surface deflection/deformation f. Energy loss due to bumps g. Air drag on inside and outside of tire

Motivation for intervehicle communication

a. Road Safety b. Traffic Efficiency c. Energy Savings