Dynamics APIs

Methods related to the Dynamics calculations are provided in this section. Note that some methods are for use in the serial systems (unconstrained), while others are specifically for use in the parallel (closed-loop) systems.

calc_M computes the joint space inertia matrix

calc_G computes the N by 1 gravity matrix

calc_InverseDynamics computes inverse dynamics using the Newton-Euler Algorithm

calc_ForwardDynamics computes forward dynamics with the Articulated Body Algorithm

calc_InverseDynamicsConstrained an inverse-dynamics operator that can be applied to fully-actuated constrained systems

calc_ForwardDynamicsConstrained computes forward dynamics with contact by constructing and solving the full lagrangian equation

calc_MInvTimesTau computes the effect of multiplying the inverse of the joint space inertia with the joint space torque vector

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calc_M

Computes the joint space inertia matrix by using the Composite Rigid Body Algorithm.

Specification:

input parameters:

const VectorNd &Q state vector of the internal joints

returns: MatrixNd M output inertia matrix

calc_G

Computes the N x 1 gravity matrix of the dynamics model by equating the velocity and acceleration to zero. This method is specifically for open_loop manipulators. For closed-loop systems use InverseDynamicsConstrained method.

Specification:

input parameters:

const VectorNd &Q state vector of the internal joints

returns: VectorNd G computed gravity vector for each joint

calc_InverseDynamics

Computes inverse dynamics with the Newton-Euler Algorithm (open-loop systems).

Specification:

input parameters:

const VectorNd &Q state vector of the internal joints

const VectorNd &QDot angular velocity vector of the internal joints

const VectorNd &QDDot angular acceleration vector of the internal joints

VectorNd &Tau actuations of the internal joints

returns: VectorNd &Tau computed torque for internal joints

calc_ForwardDynamics

Computes forward dynamics with the Articulated Body Algorithm (open-loop systems).

Specification:

input parameters:

const VectorNd &Q state vector of the internal joints

const VectorNd &QDot angular velocity vector of the internal joints

VectorNd &Tau actuations of the internal joints

const VectorNd &QDDot angular acceleration vector of the internal joints

returns: VectorNd &QDDot angular acceleration vector of the internal joints

calc_InverseDynamicsConstrained

An inverse-dynamics operator that can be applied to fully-actuated constrained systems.

Specification:

input parameters:

const VectorNd &Q state vector of the internal joints

const VectorNd &QDot angular velocity vector of the internal joints

const VectorNd &QDDotDesired N-element vector of desired generalized accelerations

ConstraintSet &CS model constraint set

const VectorNd &QDDotoutput N-element vector of generalized accelerations which satisfy the kinematic constraints

VectorNd &TauOutput N-element vector of generalized forces which satisfy the equations of motion for this constrained system

returns: VectorNd &TauOutput N-element vector of generalized forces which satisfy the equations of motion for this constrained system

calc_ForwardDynamicsConstrained

Computes forward dynamics with contact by constructing and solving the full lagrangian equation.

Specification:

input parameters:

const VectorNd &Q state vector of the internal joints

const VectorNd &QDot angular velocity vector of the internal joints

VectorNd &Tau actuations of the internal joints

ConstraintSet &CS model constraint set

const VectorNd &QDDotoutput N-element vector of generalized accelerations which satisfy the kinematic constraints

returns: const VectorNd &QDDotoutput N-element vector of generalized accelerations which satisfy the kinematic constraints

calc_MInvTimesTau

Computes the effect of multiplying the inverse of the joint space inertia matrix with a vector in linear time.

Specification:

input parameters:

const VectorNd &Q state vector of the internal joints

const VectorNd &Tau actuations of the internal joints

VectorNd &QDDot vector where the result will be stored

returns: VectorNd &QDDot` vector where the result will be stored