rajatsharma01 / carnd-pid-control-project

CarND-Controls-PID

Self-Driving Car Engineer Nanodegree Program

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Reflections

• Describe the effect each of the P, I, D components had in your implementation.

Proportional component (PID) tries to steer car towards lane center to minimize its error which is directly proportional to distance from lane center (Cross Track Error). Only using Proportional component can make car overshoot once it reaches the lane center. Because of cars momentum, it keeps oscillating around lane center and often jumps over the track boundary on curved lane.

Differential component (PID) helps avoid overshooting. While P component is trying to steer towards the lane center to minimize CTE, D component decelerates this rapid change by adding back steering in reverse direction which is proportional to rate of change in CTE. Net effect is the car arrives at lane center smoothly with lesser overshooting.

Integral component (PID) tries to address a constant systematic bias such as steering drift due to tyre rotation errors which constantly tries to pull away car from lane center. I component handles it by accounting for CTE over long period of time and steering against it which is proportional to sum of cross track errors (hence Integral).

In this project, I have assumed no drift errors in simulator, hence kept I component to be 0. Below video first runs the pid binary with D component set to 0.0 which oviously works terrible and car eventually falls off the track pretty quick. Later on, I have added back D component and car successfully completes the track.

• Describe how the final hyperparameters were chosen.

Nothing fancy here. I started with parameter values form Sebastian class and tunned them further with multiple trials, I finalized following choice of parameters:

Kp = 0.12, Ki = 0.0, Kd = 3.0

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./

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