robotic-esp / pdt

Planner Developer Tools

Planner Developer Tools (PDT)

This repository contains tools developed at ESP that aim to facilitate scientifically sound path planning research.

We're working on better documentation, but for now here's our internal documentation.

Installation

Dependencies

First install the dependencies of the tools.

OMPL

First install the dependencies of OMPL:

sudo apt update
sudo apt upgrade
sudo apt install build-essential cmake
sudo apt install libboost-all-dev
sudo apt install libeigen3-dev
sudo apt install libode-dev # optional

Some of the PDT features require our OMPL fork. You could alternatively use the regular upstream version of OMPL but will not be able to use all the PDT features.

git clone [e-mail]:robotic-esp/ompl.git
cd ompl
git fetch
git checkout main_esp
mkdir build && cd build
cmake ..
make -j 4
sudo make install

You can use git branch to check which branch you have checked out, if you are not on the main_esp branch you will need to disable some features in PDT below.

Boost

Our tools depend on the thread and program_options components of Boost, which were installed as dependencies of OMPL above.

Pangolin

Follow the installation guide of the official repo, it's well documented.

You then need to install it. From within the Pangolin directory:

sudo cmake --install build

FFmpeg

FFmpeg is only needed if you want to record videos. The code should compile without it.

sudo apt install ffmpeg

LaTeX / LuaLaTeX

The automatic report generation relies on LuaLaTeX to dynamically allocate as much memory as needed. The infallible wisdom of the internet suggests that all major LaTeX distributions include LuaLaTeX, so I figured this is not too much of an additional dependency.

sudo apt install texlive-latex-base texlive-latex-extra texlive-luatex

If running which lualatex echoes a path, you should be good to go, otherwise install lualatex.

The reporting tool loads the whole result.csv into memory. This file can be quite large, depending on logFrequency, maxTime, and the number of planners. If your system runs out of memory, ensure you have swap turned on (see, e.g., here on how to do it), or rerun experiment with a lower logFrequency, a lower maxTime, or fewer planners.

ImageMagick

The report generation uses ImageMagick to convert PDFs to PNGs. It is likely installed on your machine by default but can be installed with

sudo apt install imagemagick

If you get an error during report compilation related to "operation not allowed by the security policy `PDF'", then see you need to change your GhostScript security policy.

Doxygen and Graphviz

Doxygen and Graphviz are only necessary if you want to generate documentation. The code will compile without it.

sudo apt install doxygen graphviz xdot

The program xdot is not strictly necessary, but is a useful lightweight viewer for .dot files.

Planner Developer Tools (PDT)

This project includes two header-only libraries (N. Lohmann's JSON and A. Fallah's CSV-parser) as submodules (which is why we need to clone recursively).

git clone --recursive [e-mail]:robotic-esp/pdt.git
cd pdt
mkdir build && cd build
cmake ..
make

If you are compiling against an upstream version of OMPL, you must add -DPDT_BASE_OMPL_ONLY=TRUE to the cmake call above.

If you have Doxygen installed, you can also build the documentation

make docs

Reproducible research with Planner Developer Tools (PDT)

Most sampling-based planning algorithms depend on random numbers and can be configured by parameters (e.g., the connection radius for RRT*). Planning contexts depend on parameters as well (e.g, the number and shape of obstacles, the positions of the start and goal states, and the collision detection resolution). The result of an experiment, i.e., of a comparison of the performance of planners in a planning context, depends on the random number seed and all parameters. To reproduce an experiment, the seed and all parameters must be identical.

This is why our tools set all parameters explicitly and keep track of which parameters were set. But because explicitly specifying all parameters by hand for every experiment is tedious, the tools are shipped with a set of default parameters (you can inspect them in pdt/parameters/defaults/). The intended way to change a parameter is through a configuration patch. Parameters that are specified in such a patch can extend and overwrite the defaults.

Regardless of whether a parameter was specified in the defaults or through a patch, all accessed parameters are exported at the end of an experiment. This allows to use the exported configuration as a patch for a new experiment, which ensures that the experiment is run with the same random seed and set of parameters and therefore makes it reproducible.

Note that it is unreasonable to expect the exact same results because they depend on many aspects we cannot control, e.g., the current memory layout of the underlying system.

Running Planner Developer Tools (PDT)

Testing the installation

You can test your installation by running two demos. The first one runs a quick benchmark:

cd /path/to/pdt/build
./bin/benchmark -c ../parameters/demo/benchmark_demo.json

The above command has created the build/benchmarks/<date-string>_<context-name> directory and placed a couple of files in it, including a report that summarizes the results of the benchmark.

To test the visualization, you can run:

./bin/visualization -c ../parameters/demo/visualization_demo.json

Feel free to play around by substitution different contexts/planners into these .json files. Available options can be taken from the default config files in pdt/parameters/defaults/. The recommended way to change a default parameter is to override it by placing a parameter with the same name in the configuration provided with the -c option.

Benchmark

The tools include an executable called benchmark. This executable should be invoked as benchmark -c path/to/benchmark.json, where path/to/benchmark.json points to a configuration patch. The configuration patch has to specify a family of "Experiment" parameters, such as the planners, the planning context, and the number of runs per planner. You can find an example of a suitable configuration patch at pdt/parameters/demos/benchmark_demo.json. Notice that you can specify two planners of the same type but different configurations by giving them different names.

All experiments get their own folders in benchmarks/. The naming convention for the folders is <date-string>_<context-name>. The corresponding folder contains various files when the experiment is finished. The most important are

• config.json: All accessed parameters for this experiment;
• results.csv: The raw data of the experiment;
• report.pdf: A summary of the results of the experiment.

Visualization

At ESP we design new planning algorithms. To facilitate this, it is often helpful to visualize process of planning and not just the result. The executable visualization does exactly this. It is again invoked with a configuration patch, which specifies which planner and which context is to be visualized. You can invoke it as visualization -c path/to/visualization.json.

Implementation detail: The maxTime parameter of all planning contexts is ignored and a planner is allowed to run indefinitely when visualized. The current implementation tries to buffer iterations ahead of the currently visualized iteration. It does not perform any checks on available memory, so keep your available memory in sight as your system might freeze.

The visualization is interactive. These are the five keys that are currently bound to some action:

• 'f': forward one iteration
• 'b': backward one iteration
• 'F': forward 10% of largest computed iteration
• 'B': backward 10% of largest computed iteration
• ' ': Toggle tracking

When tracking is on, the most recently computed iteration is visualized.

Troubleshooting

The compilation fails because some headers are not found

You have built and installed the ESP version of OMPL, but the compilation fails because it is missing headers? Make sure the correct OMPL is found (cmake will report the path of the OMPL it finds). Say you installed the ESP version of OMPL to /usr/local/, but also have ROS installed on your system and cmake prefers the ROS version. You can specify the path PDT looks for OMPL in the variable PDT_OMPL_DIR, e.g., by running cmake -DPDT_OMPL_DIR=/usr/local. If you don't define the variable, CMake will look in the standard places.

Executing a program complains about missing symbols

This can happen if the wrong version of OMPL is dynamically linked to your executable. I don't have an elegant solution to this problem. A quick and dirty hack is to wrap your executable, e.g., build/bin/benchmark into a script and modify LD_LIBRARY_PATH in that script:

#!/bin/bash
export LD_LIBRARY_PATH="/usr/local/lib/:${LD_LIBRARY_PATH}"
/path/to/pdt/build/bin/benchmark -c /path/to/pdt/parameters/demo/benchmark_demo.json

The benchmark report doesn't compile

Turn on the verbose compilation in the benchmark configuration .json file. If the error is related to LuaTeX, e.g., ! LaTeX Error: file 'luatex85.sty' not found., make sure LuaTeX is installed on your system. An easy way to install it in Ubuntu is sudo apt install texlive-luatex.

Miscellaneous

Formatting code

We format our code on a style based on Google's style guide. A good way to ensure that your contribution conforms to this style is to run clang-format on it before committing. You can format a specific file with

clang-format -i ./path/to/file

or you can use

git clang-format -f

to format all lines in all files that changed between the current working directory and the last commit. You can likely also configure your editor to run clang-format for you, e.g., whenever you save a C++ file.

Statically analysing code

Please consider using static analysis tools, such as clang-tidy, when working in PDT. On Ubuntu clang-tidy can be installed from the repos (sudo apt install clang-tidy). Good editors can be configured to automatically run clang-tidy and visualize its output directly in your code. We recommend this workflow, as it doesn't require you to remember to run clang-tidy.

Alternatively, you can also run clang-tidy from the terminal. You can use it out of the box on a single file, but this requires you to specify the included directories, linked libraries, and compiler flags on the command line. For example

clang-tidy test.cpp -- -Imy_project/include -DMY_DEFINES ...

You could run clang-tidy like this on all files in the project, but you would have to find the correct includes, libraries, and flags for each file.

A less cumbersome way to run clang-tidy on a whole project is to let your build system generate a compile commands database for you and run clang-tidy from the folder in which this file is generated. In our case, you can tell CMake to generate this database by adding -DCMAKE_EXPORT_COMPILE_COMMANDS=TRUE to your call to cmake. You can then run clang-tidy on all files in the project by invoking run-clang-tidy from the folder in which the database is generated (CMake calls this file compile_commands.json and it is typically generated in the build folder).

cd /path/to/pdt/build
cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=TRUE .. 
run-clang-tidy

The run-clang-tidy executable is included in the clang-tidy package installed with sudo apt install clang-tidy.

Old Notes

How to create maps from .pngs

To create a map from a .png follow these steps:

1. Open the .png in GIMP
2. Remove shadows if necessary Layer -> Transparency -> Threshold Alpha
3. Convert to B&W Colors -> Brightness/Contrast
4. Make the background white Layer -> Transparency -> Remove Alpha Channel
5. Thicken the obstacle if necessary e.g., via 1. Select -> By Color 2. Select -> Grow 3. Edit -> Fill
6. Convert to a binary image Image -> Mode -> Indexed -> Black & White Palette
7. Save as .bmp
8. Open .bmp in MATLAB
9. Export to a csv file csvwrite('filename.csv', bmpFileName)
10. Use the csvObstacle class (currently not implemented)

Create a regression class of a planner

This allows for testing different versions of the algorithm (e.g., BIT*) in the same executable.

cd ompl/geometric/planners/
cp -r bitstar bitstar_regression
cd bitstar_regression
mv BITstar.h BITstarRegression.h
mv src/BITstar.cpp src/BITstarRegression.cpp
sed -i.bak -e 's|_BITSTAR|_BITSTARREGRESSION|g' -e 's|/bitstar|/bitstar_regression|g' -e 's|BITstar|BITstarRegression|g' BITstarRegression.h
sed -i.bak -e 's|_BITSTAR|_BITSTARREGRESSION|g' -e 's|/bitstar|/bitstar_regression|g' -e 's|BITstar|BITstarRegression|g' src/BITstarRegression.cpp
cd datastructures
sed -i.bak -e 's|_BITSTAR|_BITSTARREGRESSION|g' -e 's|/bitstar|/bitstar_regression|g' -e 's|BITstar|BITstarRegression|g' *.h
cd src
sed -i.bak -e 's|_BITSTAR|_BITSTARREGRESSION|g' -e 's|/bitstar|/bitstar_regression|g' -e 's|BITstar|BITstarRegression|g' *.cpp