PID Control Project

Control is how we use the steering, throttle, and brakes to move a car where we want it to go. When we turn through an intersection we use our intuition and experience to determine how hard to steer, when to accelerate, and whether to step on the brakes. Control algorithms are often called "controllers" and one of the most common and fundamental controllers is the PID Controller.

In this project I created a PID controller to handle the self-driving car's three actuators: steering, throttle, and brake. This controller corrects the car's driving when it makes mistakes - like overshooting turns.

Reflection Questions

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

P component stands for proportional. Using the P component, the car's steering change will always be proportional to the car's distance from the center of the lane (denoted cte).

I stands for integral. The I component helps offset the bias in the CTE that can be caused by steering drift when the car turns.

D stands for differential. Sometimes the P component overshoots the cte (center of the line), so to offset this issue we use the differential component.

Student describes the effect of the P, I, D component of the PID algorithm in their implementation. Is it what you expected?

Describe how the final hyperparameters were chosen

I started by tuning my hyperparameters manually to get myself started. I wanted to start moving in the right direction before I let Twiddle handle the rest of the parameter optimization. After the car was able to get around the track I switched to Twiddle for my optimization. I let it drive for a long time to best tune the parameters to the optimal values.

Student discusses how they chose the final hyperparameters (P, I, D coefficients). This could be have been done through manual tuning, twiddle, SGD, or something else, or a combination!

Basic Build Instructions

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

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.