Self-Driving Car Engineer Nanodegree Program

In this project, a PID controller is implemented to control a self-driving car on a simulated track.

I follow the tuning procedure on Wiki:

• First increase Kp to let the car have a steady oscillation around the desired trajectory.
• Increase Kd until the oscillation goes away.
• Slightly increase the Ki to bring the system to desired trajectory(with cte around 0). This would introduce some overshot but give the system a quicker response.

I tuned the controller manually. Initially I first use [0.1,0,0] (Kp,Ki,Kd) and slightly increase Kp to 0.13 to have a steady oscilation, then I increased the Kd term to 2.6 to stop the oscilation. I tried to increase Ki to have a quicker response but it introduce more oscilation. Therefore I set it to 0.

• The proportional gain Kp would steer the car towards the center line. But this would always overshoot.
• The integral portion would eliminate a possible bias on the controlled system. Normally it would lead to a quicker response but alse introduce a little bit oscillations.
• The differential portion helps to smooth the oscillation introduced by the Kp. But if it is too large the car would start to chatter.

• 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.