Forward Dynamics

Classes
struct	spatial_dyn::ForwardDynamicsOptions

Functions
Eigen::VectorXd	spatial_dyn::ForwardDynamics (const ArticulatedBody &ab, Eigen::Ref< const Eigen::VectorXd > tau, const std::map< size_t, SpatialForced > &f_external, const ForwardDynamicsOptions &options)
Eigen::VectorXd	spatial_dyn::ForwardDynamicsAba (const ArticulatedBody &ab, Eigen::Ref< const Eigen::VectorXd > tau, const std::map< size_t, SpatialForced > &f_external, const ForwardDynamicsOptions &options)
const Eigen::LDLT< Eigen::MatrixXd > &	spatial_dyn::InertiaInverse (const ArticulatedBody &ab)
const Eigen::MatrixXd &	spatial_dyn::InertiaInverseAba (const ArticulatedBody &ab)

Detailed Description

C++ implementation of spatial_dyn forward dynamics algorithms.

See also

Python: py_forward_dynamics

Function Documentation

ForwardDynamics()

Eigen::VectorXd spatial_dyn::ForwardDynamics	(	const ArticulatedBody &	ab,
		Eigen::Ref< const Eigen::VectorXd >	tau,
		const std::map< size_t, SpatialForced > &	f_external = {},
		const ForwardDynamicsOptions &	options = {}
	)

Compute the forward dynamics by inverting the inverse dynamics.

Uses RNEA to compute the bias torques and inverts the inertia matrix computed via CRBA to output the joint accelerations in O(n^2) time.

Parameters

ab	ArticulatedBody.
tau	Applied joint torques.
f_external	Map of (index, force) pairs where the force is the sum of all external spatial forces (represented in the world frame) applied to the associated rigid body index.
options	ForwardDynamicsOptions.

Returns

Joint accelerations.

See also

Python: spatialdyn.forward_dynamics()

ForwardDynamicsAba()

Eigen::VectorXd spatial_dyn::ForwardDynamicsAba	(	const ArticulatedBody &	ab,
		Eigen::Ref< const Eigen::VectorXd >	tau,
		const std::map< size_t, SpatialForced > &	f_external = {},
		const ForwardDynamicsOptions &	options = {}
	)

Compute the forward dynamics with ABA.

Uses the Articulated Body Algorithm (ABA) to compute the forward dynamics in O(n) time.

Parameters

ab	ArticulatedBody.
tau	Applied joint torques.
f_external	Map of (index, force) pairs where the force is the sum of all external spatial forces (represented in the world frame) applied to the associated rigid body index.
options	ForwardDynamicsOptions.

Returns

Joint accelerations.

See also

Python: spatialdyn.forward_dynamics_aba()

InertiaInverse()

const Eigen::LDLT< Eigen::MatrixXd > & spatial_dyn::InertiaInverse

(

const ArticulatedBody &

ab

)

Compute the Cholesky decomposition of the joint space inertia matrix.

Uses CRBA to compute the inertia matrix in O(n^2) time, and finds the Cholesky decomposition in O(n^2) time. Results are cached such that subsequent calls with same q will return in O(1) time.

Parameters

ab	ArticulatedBody.

Returns

Reference to the cached Cholesky decomposition of the inertia matrix.

See also

Python: spatialdyn.inertia_inverse()

InertiaInverseAba()

const Eigen::MatrixXd & spatial_dyn::InertiaInverseAba

(

const ArticulatedBody &

ab

)

Compute the inverse of the joint space inertia matrix with ABA.

Uses ABA to compute the inverse inertia matrix in O(n^2) time. Results are cached such that subsequent calls with the same q will return in O(1) time.

Parameters

ab	ArticulatedBody.

Returns

Reference to the cached inverse inertia matrix.

See also

Python: spatialdyn.inertia_inverse_aba()