CarND-Controls-PID

Self-Driving Car Engineer Nanodegree Program

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Dependencies

• cmake >= 3.5
• All OSes: click here for installation instructions
• make >= 4.1(mac, linux), 3.81(Windows)
  • 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

Basic Build Instructions

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

Tips for setting up your environment can be found here

Editor Settings

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)

Code Style

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

Project Instructions and Rubric

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.

Hints!

• 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.

Call for IDE Profiles Pull Requests

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./

How to write a README

A well written README file can enhance your project and portfolio. Develop your abilities to create professional README files by completing this free course.

My way

As I'm writing this, my PID controller is driving my car around the track. Actually, there are two PID controllers. The first and mandatory PID is steering the vehicle, while the other is controlling the throttle.

The output of a PID controller is derived from three terms. The proportional term is calculated by multiplying the current error with a scalar number. For some applications, having just a P controller is sufficient. However such a controller will not eliminate the entire error and might swing and be unstable in some +applications.

The second "I" term of the PID, integrates the error over time and creates an output that is proportional to this integral. By doing so, the I term is capable of eliminating any residual error of a P controller. However it will create overshooting by its nature and can also cause unstable swinging.

The third "D" term is calculated by multiplying the derivative/gradient of the error with a scalar value. This part of the PID controller can prevent overshooting and swinging.

After looking for a basic set of hyperparameters Kp, Ki and Kd by hand, I decided to let the computer fine-tune the parameters on its own. For one of the parameters at a time, it will try increasing and decreasing by a little bit. The results are three values for the mean squared error (gained for original parameter value, increased and decreased parameter). These three values define a parabola, where the minimum is taken for the new value of the parameter.

So, when I say, that my PID is driving the car around the track right now, it is not only driving, but actually getting better at it at the same time...