Self-Driving Car Engineer Nanodegree Program

A PID controller implemented in C++ for the 4th assignment of the second term of Udacity's Self-Driving Car Engineer Nanodegree

P, I, and D coefficients were selected manually. The aim was to have the car run inside the allowed area of the simulator, as well as making the ride as smooth as possible. Trial and error was used to find what would be "good values", as well as the effect of P, I, and D. For the last part, the values of each coefficient were modified, and the effect was observed. Furthermore, simulations were run with each of the coefficients set to zero at a time.

Twiddle, or other "automated" methods for parameter tuning were not implemented.

P – Proportional Term controls the steering angle of the car in proportion to the cross track error (CTE). When it's used alone, it makes the car always overshoot. Higher values lead to sharper turns. Value selected: Kp: 0.1

D – Differential Term Temporal derivative of the CTE. Used together with P, helps reduce overshooting. Higher values lead to smoother turns. Value selected: Kd: 4.0 I – Integral Term Counters CTE caused by systematic bias. Higher values lead to sharper turns. In the simulations run, when the value was not very small, the car was moving on a heavily oscillating track, and would often exit the road. It's value could even be set to zero, and the car would still perform satisfactory in the case of the specific simulations. Value selected: Kp: 0.000001

• cmake >= 3.5
• All OSes: click here for installation instructions
• make >= 4.1
  • Linux: make is installed by default on most Linux distros
  • Mac: install Xcode command line tools to get make
  • Windows: Click here for installation instructions
• gcc/g++ >= 5.4
  • Linux: gcc / g++ is installed by default on most Linux distros
  • Mac: same deal as make - [install Xcode command line tools]((https://developer.apple.com/xcode/features/)
  • Windows: recommend using MinGW
• uWebSockets
  • Run either ./install-mac.sh or ./install-ubuntu.sh.
  • If you install from source, checkout to commit e94b6e1, i.e.

    git clone https://github.com/uWebSockets/uWebSockets 
    cd uWebSockets
    git checkout e94b6e1
    

    Some function signatures have changed in v0.14.x. See this PR for more details.
• Simulator. You can download these from the project intro page in the classroom.

There's an experimental patch for windows in this PR

1. Clone this repo.
2. Make a build directory: mkdir build && cd build
3. Compile: cmake .. && make
4. Run it: ./pid.

We've purposefully kept editor configuration files out of this repo in order to keep it as simple and environment agnostic as possible. However, we recommend using the following settings:

• indent using spaces
• set tab width to 2 spaces (keeps the matrices in source code aligned)

Please (do your best to) stick to Google's C++ style guide.

Note: regardless of the changes you make, your project must be buildable using cmake and make!

More information is only accessible by people who are already enrolled in Term 2 of CarND. If you are enrolled, see the project page for instructions and the project rubric.

• You don't have to follow this directory structure, but if you do, your work will span all of the .cpp files here. Keep an eye out for TODOs.

Help your fellow students!

We decided to create Makefiles with cmake to keep this project as platform agnostic as possible. Similarly, we omitted IDE profiles in order to we ensure that students don't feel pressured to use one IDE or another.

However! I'd love to help people get up and running with their IDEs of choice. If you've created a profile for an IDE that you think other students would appreciate, we'd love to have you add the requisite profile files and instructions to ide_profiles/. For example if you wanted to add a VS Code profile, you'd add:

• /ide_profiles/vscode/.vscode
• /ide_profiles/vscode/README.md

The README should explain what the profile does, how to take advantage of it, and how to install it.

Frankly, I've never been involved in a project with multiple IDE profiles before. I believe the best way to handle this would be to keep them out of the repo root to avoid clutter. My expectation is that most profiles will include instructions to copy files to a new location to get picked up by the IDE, but that's just a guess.

One last note here: regardless of the IDE used, every submitted project must still be compilable with cmake and make./