/CarND-PID-Control-Project

PID controller for car navigation

Primary LanguageC++

CarND-Controls-PID

Self-Driving Car Engineer Nanodegree Program

Discussion

A video of our car is available on YouTube.

We implemented two PID controllers, one for the steering, another for the throttle. The PID controller has a built-in Twiddle function for updating parameters after every one, if so desired. We made no other changes to the logic of the car, focusing instead on the peculiar behavior of PID controllers.

We found our values using the following process:

  1. Set throttle to a constant 0.3
  2. Run Twiddle on our steering PID controller until the delta values for each parameter are less then 1E-04.
  3. Hold the steering PID controller steady.
  4. Run Twiddle on our throttle PID controller until the delta values for each parameter are less than 1E-05.
  5. Repeat steps 2 through 4 decreasing the tolerance by a factor of 10 each time, until we end with 1E-08.

Whenever we were optimizing a controller we used a common error / loss function to optimize both: we wanted to minimize average square error, while maximizing the number of iterations we could run without crashing, and also maximizing speed. Since Twiddle seeks to minimize loss, our function was (error - n - max_speed), where n was the number of iterations, error was the average squared error for all n, and max_speed was the maximum speed we obtained.

Dependencies

Basic Build Instructions

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

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./