/CarND-MPC-Project-master-master

Primary LanguageC++

CarND-Controls-MPC

Self-Driving Car Engineer Nanodegree Program

Intro

This repository contains my solution to the Udacity SDCND MPC Project. The vedio is attached in this folder named MPC.mp4(I made this video by my iphone since if I use the software on my Mac, the simulator will be influnced and the result will not be oK). You can check that. See picture below.

This solution, as the lessons suggest, makes use of the IPOPT and CPPAD libraries to calculate an optimal trajectory and its associated actuation commands in order to minimize error with a third-degree polynomial fit to the given waypoints. The optimization considers only a short duration's worth of waypoints, and produces a trajectory for that duration based upon a model of the vehicle's kinematics and a cost function based mostly on the vehicle's cross-track error (roughly the distance from the track waypoints) and orientation angle error, with other cost factors included to improve performance.

Rubric Points

##The Model**: Student describes their model in detail. This includes the state, actuators and update equations.

  • x: The x position of the vehicle.
  • y: The y position of the vehicle.
  • psi: The orientation of the vehicle.
  • v: The current velocity.
  • cte: The Cross-Track-Error
  • epsi: The orientation error

The update equation is following:

fg[1 + x_start + t] = x1 - (x0 + v0 * CppAD::cos(psi0) * dt); fg[1 + y_start + t] = y1 - (y0 + v0 * CppAD::sin(psi0) * dt); fg[1 + psi_start + t] = psi1 - (psi0 + v0 * delta0 / Lf * dt); fg[1 + v_start + t] = v1 - (v0 + a0 * dt); fg[1 + cte_start + t] = cte1 - ((f0 - y0) + (v0 * CppAD::sin(epsi0) * dt)); fg[1 + epsi_start + t] = epsi1 - ((psi0 - psides0) + v0 * delta0 / Lf * dt);

##Timestep Length and Elapsed Duration (N & dt)**: Student discusses the reasoning behind the chosen N (timestep length) and dt (elapsed duration between timesteps) values. Additionally the student details the previous values tried.

After several tryout, finally I changed the values to N=10 and dt=0.1 instead of initial value N=25 and dt=0.05.

  • Smaller dt is better because it gives finer resolution.

  • Because we use the 100ms latency, so I chose the larger value to deal with the latency.

  • Smaller value than N=10 is not enough to calculate the trajectory.

  • Polynomial Fitting and MPC Preprocessing: A polynomial is fitted to waypoints. If the student preprocesses waypoints, the vehicle state, and/or actuators prior to the MPC procedure it is described.

The waypoints are preprocessed by transforming them to the vehicle's perspective.

double x = (ptsx[i] - px) * cos(psi) + (ptsy[i] - py) * sin(psi);
double y = -(ptsx[i] - px) * sin(psi) + (ptsy[i] - py) * cos(psi);

##Model Predictive Control with Latency**: The student implements Model Predictive Control that handles a 100 millisecond latency. Student provides details on how they deal with latency.

When dealing with the latency,I chose dt=0.1 .And, I also incorporated the latency into the model.

double x = v * cos(delta) * latency;
double y = v * sin(delta) * latency;
psi = v / Lf * delta * latency;
cte = cte + v * sin(epsi) * latency;
epsi = epsi + v / Lf * delta * latency;
v = v + a * latency;

##some Update: Since I update the latency model, so the cost function parameter should be tuned.

After a long time, so I make the vehicle can run on the simulator again.

Dependencies

Basic Build Instructions

  1. Clone this repo.
  2. Make a build directory: mkdir build && cd build
  3. Compile: cmake .. && make
  4. Run it: ./mpc.

Tips

  1. It's recommended to test the MPC on basic examples to see if your implementation behaves as desired. One possible example is the vehicle starting offset of a straight line (reference). If the MPC implementation is correct, after some number of timesteps (not too many) it should find and track the reference line.
  2. The lake_track_waypoints.csv file has the waypoints of the lake track. You could use this to fit polynomials and points and see of how well your model tracks curve. NOTE: This file might be not completely in sync with the simulator so your solution should NOT depend on it.
  3. For visualization this C++ matplotlib wrapper could be helpful.)
  4. Tips for setting up your environment are available here
  5. VM Latency: Some students have reported differences in behavior using VM's ostensibly a result of latency. Please let us know if issues arise as a result of a VM environment.

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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