Self-Driving Car Engineer Nanodegree Program

• 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

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

Below i am going to briefly describe some of the steps i took in this project.

I started of by coding the various template functions in PID.cpp. This was relatively straightforward and I essentially replicated the code/formula from the project lessons.

Thereafter, i had to call the Init, UpdateError and TotalError for the steering value. After a lot of manual tuning I settled for the following values.

Kp = 0.15 Ki = 0.001 Kd = 2.75

As comments in the code, I still have other combinations that worked as well.

With the above values for steering PID, the car will not leave the track at all.

After this, I took notice of the fact that there was a comment in the code which said that another PID could be used.

I decided to use another PID for the throttle value. I was successful to some extent or so i believe. I decided to cap my speed at 45 MPh.

Again after some manual tuning i settled for the following values for the throttle PID.

Kp = 0.2 Ki = 0.01 Kd = 1.0

The issue with the throttle PID, is in the first quarter of lap 1, the car accelerates to a very high speed of almost 75 Mph. Thereafter, the car can go around any number of laps and the speed will be fixed at around 45 Mph.

I tried to fix this by tracking the speed. Whenever the speed is more than 46 Mph, I cap the throttle value at 0.1 However, I got mixed results with this. This is something that I will need to work on later.

For the submission i commented out the above mentioned code snippet to avoid wild oscillations. Though the second PID seems to work, i need to perfect it to avoid instability. Things were more stable with just one PID for the steering value.