Midterm Cheat Sheet

Lec Week 1 - Introduction to Autonomous Vehicles (Types, Key concepts & components of AVs; safety frameworks, regulations, ethics) 1. [5pts] What is 'Connected AV' mean?  Relies on inputs from other vehicles, devices, or smart infrastructure (AV truck convoy) 2. [4pts] An autonomous mobile robot used to make room deliveries in a hotel is called what type of robot?  Service Robots – operating generally indoors 3. [4pts] What kind of autonomous mobile robot is this? (name and acronym)  Unmanned Surface Vehicle (USV) – water mobile robot on surface 4. [4pts] Adaptive speed control falls at what level in the SAE driving autonomy scale?  SAE Level 1 – provide steering OR brake/acceleration support 5. [4pts] A military drone takes off and flies independently to a target waypoint but requires a human to remotely target and release weapons. What level of autonomy is this drone?  Level 4 (High Autonomy) – pilot can monitor flight remotely 6. [4pts] The process of a robot determining/tracking its position is known as localization 7. [4pts] Which standard details how to demonstrate an autonomous vehicle can operate without human supervision?  Evaluation of Autonomous Products (ANSI/UL4600) – proves safety of autonomous road vehicles operating w/out human 8. [4pts] Which standard details how to design and evaluate AVs are safe against external hacking and tricking attacks?  Cybersecurity engineering (ISO/SAE 21434) – protect safety functions from compromise, attacks, unauthorized access, damage 9. [6pts] Briefly describe what ASIL is and what it describes  Automotive Safety Integrity Levels – way of describing the hazards w/vehicle functions & giving a level of the severity 10. [4pts] National standards/regulations govern the use of autonomous vehicles on public roadways (TRUE | FALSE).  False – NHTSA has issued guidelines but no formal regulations for AV 11. [7pts] I work at a large manufacturing facility with multiple buildings at different sites (fairly close together) on either side of a public road. I am planning to use AV drones to fly maintenance spare parts (under 10lbs) between buildings; the drone itself is 20 lbs. It is planned for the drones to be fully autonomous and line of sight monitoring is not possible. What needs to be done to be in compliance with federal regulations? 12. [10pts] An AV is coming up on a bicyclist on a one lane each direction road (as shown in figure); the bike is sharing the lane. What actions are available to the AV? Discuss in context of the ethical frameworks we discussed.  The vehicle should follow behind the cyclist at a safe distance until there is no oncoming traffic from the other lane. When it is safe, the vehicle can then cross the centerline to avoid hitting the cyclist and pass him. Lec Week 2-3 – Mobile Kinematics (3 DOF and 6 DOF space mobile robots; odometry and dead reckoning) 13. [6pts] How many controlled degrees of freedom does a differential robot have? And what are they?  2 DOF – x- and y-translation 14. [4pts] Is a differential robot non-holonomic, holonomic, or redundant?  Non-holonomic – the number of controllable DOF of the robot is smaller than the number of DOF of the robot 15. [20pts] A differential robot starts a move at base frame pose [ X=140", Y=300",  = -25  ]. The robot has 1.5" radius wheels and a 5" track width between wheels. The robot moves at  L = 6 radians/sec,  R = 8 radians/sec for 20 seconds. Assuming instantaneous acceleration and ideal driving conditions, what is the robot's pose in the base frame at the end of the 20 seconds? Show all work. x ( t ) = x 0 + ∫ t 0 t V ( t ) cos [ θ ( t ) ] = x 0 + r 2 ∫ t 0 t { ω R ( t ) + ω L ( t ) cos [ θ ( t ) ]} dt →x ( 20 ) = 140+ {1.5 ¿ 2 ∫ 0 20 [ 8 + 6cos ( − 25 ° ) ] dt = 341.6} ¿ y ( t ) = y 0 + ∫ t 0 t V ( t ) sin [ θ ( t ) ] = y 0 + r 2 ∫ t 0 t { ω R ( t ) + ω L ( t ) sin [ θ ( t ) ]} dt → y ( 20 ) = 300+ {1.5 ¿ 2 ∫ 0 20 [ 8 + 6sin ( − 25 ° ) ] dt = 222.0} ¿ θ ( t ) = θ 0 + ∫ t 0 t ω ( t ) dt = θ 0 + 1 L ∫ t 0 t [ ω R ( t ) − ω L ( t ) ] dt =− 25 ° + 1 5} int from {0} to {20} {left (8-6 right ) dt=-17°} ¿ 16. [10pts] Differential robot with base frame pose [ X=10", Y= -45",  = -0.2 radians]. The robot has 1" radius wheels and a 6" track width between wheels. The robot moves at  L = 6 radians/sec,  R = 8 radians/sec. Location of ICC in the base frame and radius of curvature?

v L = r ω L = ( 1 ) ( 6 ) = 6 ¿ s ; v R = r ω R = ( 1 ) ( 8 ) = 8 ¿ s ;ω = v R − v L L = 8 − 6 6 = 1 3 rad s R = L 2 v R + v L v R − v L = 6 2 8 + 6 8 − 6 = 21 ; ICC=[ matrix {x-Rsin(θ) ## y+Rcos(θ)} ]=[ matrix {10-21 sin (-0.2) ## -45+21 cos (-0.2 17. [10pts] Differential robot at base frame pose [ X=140", Y=300",  = -25  ]. Target (objective) is [ X=200", Y=400"] (any orientation). How would you move the robot to get there? (define wheel speeds and time for each move; can be more than one move) 18. [20pts] Ackermann drive mobile robot. A function cmdVel() ( vel, steering_angle = cmdVel() ) is available to get the current linear velocity and steering angle. There are also some global variables defined curX, curY, curYaw, lastUpdate, defining the current pose estimate and time odometry was last updated. Write a Python function that will update these 4 global variables each time called. import time def cmdVel (): # Sample function cmdVel() returning linear velocity and steering angle return 1.0, 0.2 # Global variables curX = 0.0 curY = 0.0 curYaw = 0.0 lastUpdate = time.time() def updateGlobalVariables (): # Function to update global variables based on current velocity and steering angle global curX, curY, curYaw, lastUpdate vel, steering_angle = cmdVel() # Get current linear velocity and steering angle from cmdVel() currentTime = time.time() # Time since the last update deltaTime = currentTime – lastUpdate # Update the pose estimate curX += vel*deltaTime*(0.5*math.cos(curYaw) + math.cos(curYaw + steering_angle))) curY += vel*deltaTime*(0.5*math.sin(curYaw) + math.sin(curYaw + steering_angle))) curYaw += vel/L*math.tan(steering_angle*deltaTime lastUpdate = currentTime # Update the last update time updateGlobalVariables() # Call updateGlobalVariables() when you want to update the pose 19. [6pts] Explain what dead reckoning is and why it not by itself useful for navigation  Dead reckoning uses wheel and heading sensors to update the position. It is the process of calculating the current position of a moving object by using a previously determined position, or fix, and by using estimations of speed and heading direction over elapsed time. It is not useful by itself for navigation because there are uncertainties associated with this process such as numerical integration errors, unequal wheel diameters, variation in the contact point of the wheel/unequal floor contact, and sensor errors. Lec Weeks 4,6,7 – Perception (Range Sensors [infrared, ultrasound, LIDAR, RADAR], Computer Vision) 20. [5pts] Give an example of a proprioceptive sensor on a mobile robot:  Proprioceptive sensors measure the internal state of the robot (movements, position, internal parameters). Examples include encoders, accelerometers, gyroscopes, IMUs, tilt/inclinometers, and compasses 21. [6pts] What impact might sensor bandwidth have on control of an AV?  The sensor bandwidth is the rate at which sensors can acquire and process data. It influences the control performance of the AV (contributes to responsiveness, accuracy, stability, and adaptability). They can impact response time, accuracy and precision, control stability, and object detection & tracking. 22. [6pts] Explain the difference between accuracy and precision in sensor readings.  Accuracy is how close a measurement is to the target value; precision is the repeatability/consistency of measurements. 23. [4pts] A gyroscope is used to measure linear velocities along X, Y, and Z axis ( TRUE | FALSE ) FALSE – measure orientation & angular vel 24. [4pts] What kind of sensor unit do I need to track both linear and angular velocities? Inertial Measurement Units (IMU’s) or INS or IRU 25. [4pts] Name the ROS2 message type you would use for a 2D laser scanner. (or for GPS position, LIDAR, odometry, etc.)

 Delete file "xyz.py" in directory "~/ws/src/pkg1/pkg1": rm ~/ws/src/pkg1/pkg1/xyz.py  Delete directory "tmp" in your home directory and any of the folders and files in it: rm -r ~/tmp  Copy all the files in the directory "~/ws/src/pkg1/" to the directory "~/repo/pkg1": cp -r ~/ws/src/pkg1/* ~repo/pkg1/  In the workspace src directory "~/ws/src", make a directory "pkg2" with a "models" directory under it:mkdir -p ~ws/src/pkg2/models 47. [5pts] Give the Linux terminal command(s) to view all uncommitted files in a git repo: git status -u 48. [5pts] You checkout, edit and save a file in a git repo project. What needs to be done to commit it to the project repo?  Add changes to staging area: git add modified_file.txt or git add . (adds all changes); Commit the changes: git commit -m “message”; Push changes: git push 49. [8pts] You are creating a git repo for a new project in Linux. Give the git commands needed to initialize it.  Navigate to directory: cd /path; Initialize git repository: git init; Create README file: nano README.md; Add & commit README file: git add README.md, git commit -m “Initial commit with README” 50. [5pts] What is the purpose of the SSH key we created and added to your Linux and GitHub site?  Provides a secure & authenticated communication channel between local machine and the GitHub server. Steps: Generate SSH key pair; Add public key to GitHub; Use SSH for Git operations 51. [7pts] You want to download a public ROS2 examples package ( https://github.com/ros2/examples.git ) to a local ROS2 workspace directory ("~/ws/src/examples"). Provide the Linux command(s) to accomplish this.  git clone https://github.com/ros2/examples.git ~/ws/src/examples; Clones the ROS2 examples repository and places in workspace 52. [5pts] From the command prompt in a Linux terminal, provide the command to:  View all active ROS 2 topics: ros2 topic list  View all active ROS 2 nodes: ros2 node list  View all active ROS 2 services: ros2 service list  View the structure of message type "sensor_msgs/LaserScan": ros2 interface show sensor_msgs/msg/LaserScan  Subscribe to topic "/lab02/ControllerInfo": ros2 topic echo /lab02/ControllerInfo  Launch package "labX" with launch file "world1.launch.py": ros2 launch labX world1.launch.py 53. [7pts] In ROS2, how do topics, services, and actions differ?  Topics are suitable for broadcasting data to multiple nodes asynchronously; Services are used for synchronous one-to-one communication with a request & reply; Actions are employed for more complex, asynchronous one-to-one communication with goals, feedback, and results 54. [5pts] In ROS2, what are Parameters?  Mechanism for storing & retrieving configuration data at runtime. Provide a way to dynamically configure & tune behavior of noes in a ROS2 system. Offer a centralized & standardized way to manage configuration settings. 55. [5pts] What is a ROS bag?  A file format in ROS used to store & replay ROS message data. Way to record data generated by ROS nodes during the runtime a robotic system. 56. [5pts] What is a ROS message type?  Structured data type used for communication between different nodes. 57. [5pts] What is the purpose of a launch file in a ROS2 package?  Used to specify & launch multiple ROS nodes & associated parameters with a single command. Node configuration, Node grouping, Parameterization, Namespace management, Remapping, Conditionals & loops, Composability, Launch description language (LDL) 58. [5pts] What is the purpose of setup.py in a Python ROS2 package?  Enabling the build, installation, & distribution of the ROS package. Key purposes are: package metadata, dependencies specification, package installation, package entry points, test configuration, and distribution. 59. [5pts] What is a ROS 2 Package?  Encapsulates & organizes the code, configuration, & resources related to a specific piece of functionality or component within a system. Used to structure & modularize code in a way that facilitates the development, deployment, & reuse of robotic software. 60. [5pts] What does an SDF file define?  Defines the structure & properties of elements in a robot/simulation environment. Provides a way to describe various aspects of the systems, including models, sensors, actuators, physics, & environment enabling interoperability across frameworks. 61. You are writing the code for a Python node file, which contains a class Navigator(Node). Write the Python code to:  [6pts] In the __init__ function, initiate a new class property "targetOrientation" to 0.0 (only write the line of code to accomplish this, not the function)  [7pts] In the __init__ function, register a subscription for topic name "MyTopics/cmd_vel" of type Twist, which will callback a function defined elsewhere in your class called "velocityCallback", and a queue length of 15 (only write the line of code to accomplish this, not the __init__ function or callback function)  [10pts] Define a callback function "stringCallback" for a topic with message type string. The function should extract the string data from the message and print it to the terminal. # Initiating a new class property “targetOrientation” in the __init__ function self.targetOrientation = 0.0 # Registering subscription for topic “MyTopics/cmd_vel” of type Twist w/callback function “velocityCallback” & a queue length of 15 self.create_subcription(Twist, ‘ MyTopics/cmd_vel’ , self.velocityCallback, 15) # Defining the callback function “stringCallback” for a topic with message type string def stringCallback (self, msg): # Extracting string data from the message & printing it to the terminal string_data = msg.data print( f”Received string message {string_data}” )

62. [5pts] What build system is used in ROS 2? And what build type is used for Python-only packages?  The default build system in ROS 2 is colcon (a build tool for development & building of software packages in ROS 2). For Python-only packages in ROS 2, the build type is the “ament_python” build type (specifically designed for building ROS 2 packages that consist entirely of Python code.