RigidBodyDynamics

RigidBodyDynamics implements various rigid body dynamics and kinematics algorithms.

Design features

Some of the key design features of this package are:

• pure Julia implementation, enabling seamless support for e.g. automatic differentiation using ForwardDiff.jl and symbolic dynamics using SymPy.jl.

• easy creation and modification of general rigid body mechanisms (including basic URDF parsing).

• extensive checks that verify that coordinate systems match before computation, with the goal of making reference frame mistakes impossible

• flexible caching of intermediate results to prevent doing double work

• fairly small codebase and few dependencies

• singularity-free rotation parameterizations

Functionality

Current functionality of RigidBodyDynamics includes:

• kinematics/transforming points and free vectors from one coordinate system to another

• transforming wrenches, momenta (spatial force vectors) and twists and their derivatives (spatial motion vectors) from one coordinate system to another

• relative twists/spatial accelerations between bodies

• kinetic/potential energy

• center of mass

• geometric/basic/spatial Jacobians

• momentum

• momentum matrix

• momentum rate bias (= momentum matrix time derivative multiplied by joint velocity vector)

• mass matrix (composite rigid body algorithm)

• inverse dynamics (recursive Newton-Euler)

• dynamics

• simulation, either using an off-the-shelf ODE integrator or using an included custom Munthe-Kaas integrator that properly handles second-order ODEs defined on a manifold.

There is currently partial support for closed-loop systems (parallel mechanisms); more features will be added soon in this area. Contact is not yet supported.

Installation

Installing Julia

Download links and more detailed instructions are available on the Julia website.

Installing RigidBodyDynamics

To install the latest tagged release of RigidBodyDynamics, simply run

Pkg.add("RigidBodyDynamics") 

To check out the master branch and work on the bleeding edge, additionally run

Pkg.checkout("RigidBodyDynamics")

RigidBodyDynamics currently only supports version 0.5 of Julia.

About

This library was inspired by IHMCRoboticsToolkit and by Drake.

Most of the nomenclature used and algorithms implemented by this package stem from the following resources:

• Murray, Richard M., et al. A mathematical introduction to robotic manipulation. CRC press, 1994.

• Featherstone, Roy. Rigid body dynamics algorithms. Springer, 2008.

• Duindam, Vincent. Port-based modeling and control for efficient bipedal walking robots. Diss. University of Twente, 2006.

Related packages

• RigidBodyTreeInspector.jl - 3D visualization of RigidBodyDynamics.jl Mechanisms using Director.

Contents

• Quick start guide
• Spatial vector algebra
• Index
• Types
• The @framecheck macro
• Functions
• Joints
• Index
• The Joint type
• Functions
• JointTypes
• Rigid bodies
• Index
• The RigidBody type
• Functions
• Mechanisms
• Index
• The Mechanism type
• Creating and modifying Mechanisms
• Basic functionality
• MechanismState
• Index
• The MechanismState type
• Functions
• Algorithms
• Index
• The DynamicsResult type
• Functions
• Simulation
• Index
• Basic simulation
• Lower level ODE integration interface
• Benchmarks

Citing this library

@misc{rigidbodydynamicsjl,
 author = "Twan Koolen and contributors",
 title = "RigidBodyDynamics.jl",
 year = 2016,
 url = "https://github.com/tkoolen/RigidBodyDynamics.jl"
}