📖 Documentation

API Documentation: docs.allen-liu.net/modern-robotics-cpp
Source Code: github.com/nu-jliu/modern-robotics-cpp
Textbook: modernrobotics.org

🛠️ Requirements

Component	Minimum Version	Tested Version
OS	Ubuntu 22.04+	Ubuntu 22.04.5 LTS
CMake	3.16+	3.22.1
Compiler	GCC 9+ or Clang 10+	GCC 11.4.0
Armadillo	9.900+	10.8.2

🚀 Features

This library provides a complete implementation of fundamental robotics algorithms organized by textbook chapters:

Core Modules

🔄 Rigid-Body Motions (Chapter 3)
- Rotation matrices and homogeneous transformations
- Screw theory and exponential coordinates
- Adjoint representations
🎯 Forward Kinematics (Chapter 4)
- Product of exponentials formula
- Open-chain manipulator kinematics
- Body and space frame representations
⚡ Velocity Kinematics & Statics (Chapter 5)
- Jacobian computation and analysis
- Velocity relationships and singularities
- Static force analysis
📈 Inverse Kinematics (Chapter 6)
- Newton-Raphson iterative algorithms
- Numerical inverse kinematics solutions
🔧 Dynamics of Open Chains (Chapter 8)
- Forward and inverse dynamics
- Mass matrix computation
- Coriolis and gravitational effects
📊 Trajectory Generation (Chapter 9)
- Point-to-point trajectory planning
- Cubic and quintic polynomial time scaling
- Joint space, screw motion, and Cartesian trajectories
🎮 Robot Control (Chapter 11)
- Computed torque control implementation
- PID feedback control with feedforward
- Control simulation and trajectory tracking
🔧 Utilities
- Mathematical constants and tolerance settings
- Vector normalization and near-zero checking
- Common robotics utility functions

📦 Installation

Prerequisites

Install required dependencies on Ubuntu:

# Install build tools and dependencies
sudo apt update
sudo apt install build-essential cmake git
sudo apt install libarmadillo-dev

Build from Source

# Clone the repository
git clone https://github.com/nu-jliu/modern-robotics-cpp.git
cd modern-robotics-cpp
 
# Configure and build
mkdir build && cd build
cmake -DCMAKE_BUILD_TYPE=Release -DBUILD_TESTS=ON -DBUILD_DOCS=ON ..
make -j$(nproc)
 
# Install system-wide (optional)
sudo make install

Build Options

-DBUILD_TESTS=ON - Build unit tests
-DBUILD_DOCS=ON - Generate API documentation
-DCMAKE_BUILD_TYPE=Release - Optimized release build

💡 Quick Start

Basic Usage Examples

Rigid Body Motions

#include <iostream>
#include <modern_robotics/all.hpp>
 
int main() {
    // Create a rotation matrix
    arma::mat33 R = {{1, 0, 0},
                     {0, 0, -1},
                     {0, 1, 0}};
    
    // Convert to axis-angle representation
    arma::vec3 omg;
    double theta;
    mr::AxisAng3(R, omg, theta);
    
    std::cout << "Rotation axis: " << omg.t();
    std::cout << "Rotation angle: " << theta << " rad" << std::endl;
    
    return 0;
}

Trajectory Generation

#include <modern_robotics/trajectory_generation.hpp>
 
// Generate a joint space trajectory
arma::vec thetastart = {0, 0, 0};
arma::vec thetaend = {1.57, 0.5, -0.3};
double Tf = 3.0;  // 3 seconds
size_t N = 100;   // 100 points
 
auto trajectory = mr::JointTrajectory(thetastart, thetaend, Tf, N, 
                                     mr::Method::Quintic);

Robot Control

#include <modern_robotics/robot_control.hpp>
 
// Compute control torques using PID + feedforward
arma::vec tau = mr::ComputeTorque(thetalist, dthetalist, eint, g, 
                                 Mlist, Glist, Slist,
                                 thetalistd, dthetalistd, ddthetalistd,
                                 kp, ki, kd);

CMake Integration

find_package(modern_robotics REQUIRED)
 
add_executable(your_robot_app src/main.cpp)
target_link_libraries(your_robot_app PUBLIC modern_robotics::modern_robotics)

Testing Your Installation

# Run all tests
cd build && ctest
 
# Run specific module tests
./build/tests/test_rigid_body_motions
./build/tests/test_forward_kinematics

🏗️ Project Structure

modern-robotics-cpp/
├── include/modern_robotics/              # Public headers
│   ├── all.hpp                          # Convenience header (includes everything)
│   ├── rigid_body_motions.hpp           # Chapter 3: Rotations & transformations
│   ├── forward_kinematics.hpp           # Chapter 4: Forward kinematics
│   ├── velocity_kinematics_and_statics.hpp # Chapter 5: Jacobians & velocity
│   ├── inverse_kinematics.hpp           # Chapter 6: Inverse kinematics
│   ├── dynamics_of_open_chains.hpp      # Chapter 8: Dynamics algorithms
│   ├── trajectory_generation.hpp        # Chapter 9: Motion planning
│   ├── robot_control.hpp                # Chapter 11: Control algorithms
│   └── utils.hpp                        # Mathematical utilities
├── src/                                 # Implementation files (.cpp)
├── tests/                               # Unit tests (Catch2 framework)
│   ├── test_rigid_body_motions.cpp
│   ├── test_forward_kinematics.cpp
│   ├── test_velocity_kinematics_and_statics.cpp
│   ├── test_inverse_kinematics.cpp
│   ├── test_dynamics_of_open_chains.cpp
│   ├── test_trajectory_generation.cpp
│   ├── test_robot_control.cpp
│   └── test_utils.cpp
├── build/                               # Build directory (generated)
├── CMakeLists.txt                       # CMake configuration
├── Doxyfile.in                         # Doxygen documentation config
├── CLAUDE.md                           # Claude Code development guide
└── LICENSE                             # MIT License

🧪 Development

Running Tests

cd build
ctest --verbose              # Run all tests with output
ctest -R rigid_body         # Run specific test group
 
# Run individual test executables
./tests/test_rigid_body_motions
./tests/test_forward_kinematics
./tests/test_velocity_kinematics_and_statics
./tests/test_inverse_kinematics
./tests/test_dynamics_of_open_chains
./tests/test_trajectory_generation
./tests/test_robot_control
./tests/test_utils

Generating Documentation

cd build
make doc                    # Generates docs in build/docs/html/
# Open documentation: firefox build/docs/html/index.html

Code Architecture & Design

This library follows modern C++ best practices and robotics conventions:

Type System

Armadillo matrices: arma::mat33, arma::mat44, arma::mat66 for fixed-size matrices
Armadillo vectors: arma::vec3, arma::vec6, arma::vec for dynamic vectors
Const correctness: Functions return const values to prevent accidental modification
Namespace: All functionality contained within mr namespace

Parameter Conventions

Parameter names match textbook notation exactly (e.g., Slist, Blist, thetalist)
Slist: Screw axes in space frame (6×n matrix as vector of 6-vectors)
Blist: Screw axes in body frame (6×n matrix as vector of 6-vectors)
Mlist: Link frames relative to previous frame (vector of 4×4 matrices)
Glist: Spatial inertia matrices (vector of 6×6 matrices)

Mathematical Constants

Global tolerance: mr::tolerance = 1e-6
Utility functions for near-zero checking and vector normalization

Testing Framework

Catch2 framework for comprehensive unit testing
Floating-point comparisons use Catch::Matchers::WithinAbs(expected, TOLERANCE)
Each module has corresponding test file with mathematical validation

📄 License

This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

📚 References

Lynch, K. M., & Park, F. C. (2017). Modern Robotics: Mechanics, Planning, and Control. Cambridge University Press.
Official textbook website: modernrobotics.org

👨‍💻 Author

Jingkun Liu

GitHub: @nu-jliu
Portfolio: allen-liu.net