CarND-PID-Control-Project

Self-Driving Car Engineer Nanodegree Program

Reflection

Describe the effect each of the P, I, D components had in your implementation.
The P component is the proportional part of the controller. It's the difference between target value and sensor reading. In our case it gets computed by the simulator and is called cte or cross track error. The higher it gets the higher the result of the controller. It pulls the car towards the target point and gets smaller the closer it gets.
The D component is the derivative part of the P component. It's the difference of the current error and the previous error divided by the time passed between measurements. It prevents overshooting and therefore an oscillation of the car but slows down the response of the controller.
The I component is the integral part of the controller. It's basically the sum of all error values sent from the simulator. It can increase the response time but too high gain values can cause oscillation and a instable controller.
Describe how the final hyper-parameters were chosen.
I first implemented a twiddle algorithm to automatically tune the parameters. After several runs which never lead to satisfying results, I removed it and started with manual tuning.
In hindsight was not the implementation faulty but the high latency between simulator and web socket. To tune manually I used following flowchart:

This might not be the fastest and most accurate way of tuning a PID controller but it gave me a feeling and understanding of the individual constants Kp, Kd and Ki.
My final values are (0.15, 0.0005, 1.8) for Kp, Kd and Ki respectively. Those parameters were tuned with the v1.45 simulator on lowest graphics quality and a screen resolution of 960x720.

Dependencies

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

Basic Build Instructions

Clone this repo.
Make a build directory: mkdir build && cd build
Compile: cmake .. && make
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./

SiRi13/CarND-PID-Control-Project