Base class encoding the 6DOF hydrodynamic model of a marine vehicle. More...

#include <SystemDynamicsBase.h>

Inheritance diagram for SystemDynamicsBase:

Public Member Functions
	SystemDynamicsBase (const bool is_3dof)
	Constructs the dynamics base and sets the DOF flag. More...

virtual	~SystemDynamicsBase ()=default
	Virtual destructor. More...

const Matrix6d &	get_m () const
	Returns the total mass matrix M = Mrb + Ma. More...

const Matrix6d &	get_mrb () const
	Returns the rigid-body mass matrix Mrb. More...

const Matrix6d &	get_ma_matrix () const
	Returns the added-mass matrix Ma. More...

const Matrix6d &	get_dl_matrix () const
	Returns the linear damping matrix Dl. More...

const Matrix6d &	get_dnl_matrix () const
	Returns the quadratic damping matrix Dnl. More...

const Vector3d &	get_rgb_vec () const
	Returns the centre of gravity in the body frame. More...

const Vector3d &	get_rbb_vec () const
	Returns the centre of buoyancy in the body frame. More...

const Vector3d &	get_fgn () const
	Returns the gravitational force vector in the world frame. More...

const Vector3d &	get_fbn () const
	Returns the buoyancy force vector in the world frame. More...

double	get_mass_value () const
	Returns the vehicle mass in kg. More...

double	get_weight () const
	Returns the vehicle weight in N. More...

double	get_buoyancy_value () const
	Returns the net buoyancy force in N. More...

Matrix6d	get_d (const Vector6d &velocity) const
	Evaluates the total damping matrix D(v) = Dl + Dnl*diag(\|v\|) More...

Matrix6d	get_crb (const Vector6d &velocity) const
	Evaluates the rigid-body Coriolis matrix Crb(v) More...

Matrix6d	get_ca (const Vector6d &velocity) const
	Evaluates the added-mass Coriolis matrix Ca(v) More...

Matrix6d	get_c (const Vector6d &velocity) const
	Evaluates the total Coriolis matrix C(v) = Crb(v) + Ca(v) More...

Vector6d	get_g (const Quaterniond &q) const
	Evaluates the 6DOF gravitational and buoyancy restoring vector G(q) More...

Vector6d	get_g (const Vector3d &rpy) const
	Evaluates the 6DOF gravitational and buoyancy restoring vector G(rpy) More...

virtual Vector6d	get_inverse_dynamics (const Vector6d &velocity, const Vector6d &acceleration, const Quaterniond &orientation) const
	Computes the inertial + Coriolis + damping force Ma + C(v)v + D(v)*v. More...

void	set_mass (double m)
	Sets vehicle mass and recomputes weight, buoyancy, and the rigid-body mass matrix. More...

void	set_buoyancy (double factor)
	Sets the buoyancy force as a scale factor relative to vehicle weight. More...

void	set_i (const std::array< double, 6 > &I)
	Sets the rigid-body inertia tensor. More...

void	set_ma (const std::array< double, 6 > &m)
	Sets the diagonal added-mass coefficients. More...

void	set_dl (const std::array< double, 6 > &d)
	Sets the diagonal linear damping coefficients. More...

void	set_dnl (const std::array< double, 6 > &d)
	Sets the diagonal quadratic (nonlinear) damping coefficients. More...

void	set_rbb (const std::array< double, 3 > &rbb)
	Sets the centre-of-buoyancy position in the body frame. More...

void	set_rgb (const std::array< double, 3 > &rgb)
	Sets the centre-of-gravity position in the body frame. More...

Public Attributes
const bool	is_system_3dof_
	True if the vehicle is constrained to the XY-Yaw plane (3DOF surface vehicle) More...

Detailed Description

Base class encoding the 6DOF hydrodynamic model of a marine vehicle.

Stores mass, inertia, damping, and buoyancy parameters and provides methods to evaluate the Coriolis matrix C(v), damping matrix D(v), restoring vector G(q), and the inertial + Coriolis + damping expression M*a + C(v)*v + D(v)*v. G(q) is computed separately and applied by BuoyancyController. Subclasses may override get_inverse_dynamics() to zero out irrelevant DOFs.

Invariant: M_ = Mrb_ + Ma_ must hold after every mutation. All setters that modify Mrb_ or Ma_ call update_mass() to re-establish this.

Constructor & Destructor Documentation

◆ SystemDynamicsBase()

SystemDynamicsBase::SystemDynamicsBase ( const bool is_3dof )

explicit

Constructs the dynamics base and sets the DOF flag.

Parameters

is_3dof [in] True for a surface vehicle constrained to XY-Yaw

◆ ~SystemDynamicsBase()

virtual SystemDynamicsBase::~SystemDynamicsBase ( )

virtualdefault

Virtual destructor.

Member Function Documentation

◆ get_buoyancy_value()

double SystemDynamicsBase::get_buoyancy_value ( ) const

inline

Returns the net buoyancy force in N.

◆ get_c()

Matrix6d SystemDynamicsBase::get_c ( const Vector6d & velocity ) const

Evaluates the total Coriolis matrix C(v) = Crb(v) + Ca(v)

Parameters

velocity [in] 6DOF body-frame velocity

Returns: 6x6 total Coriolis matrix

◆ get_ca()

Matrix6d SystemDynamicsBase::get_ca ( const Vector6d & velocity ) const

Evaluates the added-mass Coriolis matrix Ca(v)

Parameters

velocity [in] 6DOF body-frame velocity

Returns: 6x6 added-mass Coriolis matrix

◆ get_crb()

Matrix6d SystemDynamicsBase::get_crb ( const Vector6d & velocity ) const

Evaluates the rigid-body Coriolis matrix Crb(v)

Parameters

velocity [in] 6DOF body-frame velocity

Returns: 6x6 rigid-body Coriolis matrix

◆ get_d()

Matrix6d SystemDynamicsBase::get_d ( const Vector6d & velocity ) const

Evaluates the total damping matrix D(v) = Dl + Dnl*diag(|v|)

Parameters

velocity [in] 6DOF body-frame velocity

Returns: 6x6 velocity-dependent damping matrix

◆ get_dl_matrix()

const Matrix6d& SystemDynamicsBase::get_dl_matrix ( ) const

inline

Returns the linear damping matrix Dl.

◆ get_dnl_matrix()

const Matrix6d& SystemDynamicsBase::get_dnl_matrix ( ) const

inline

Returns the quadratic damping matrix Dnl.

◆ get_fbn()

const Vector3d& SystemDynamicsBase::get_fbn ( ) const

inline

Returns the buoyancy force vector in the world frame.

◆ get_fgn()

const Vector3d& SystemDynamicsBase::get_fgn ( ) const

inline

Returns the gravitational force vector in the world frame.

◆ get_g() [1/2]

Vector6d SystemDynamicsBase::get_g ( const Quaterniond & q ) const

Evaluates the 6DOF gravitational and buoyancy restoring vector G(q)

Parameters

q	[in] Vehicle orientation as a unit quaternion

Returns: 6-element restoring force/torque vector in N and Nm

◆ get_g() [2/2]

Vector6d SystemDynamicsBase::get_g ( const Vector3d & rpy ) const

Evaluates the 6DOF gravitational and buoyancy restoring vector G(rpy)

Parameters

rpy	[in] Vehicle orientation as roll-pitch-yaw in radians

Returns: 6-element restoring force/torque vector in N and Nm

◆ get_inverse_dynamics()

Vector6d SystemDynamicsBase::get_inverse_dynamics	(	const Vector6d &	velocity,
		const Vector6d &	acceleration,
		const Quaterniond &	orientation
	)		const

virtual

Computes the inertial + Coriolis + damping force M*a + C(v)*v + D(v)*v.

Does NOT include the gravitational/buoyancy restoring term G(q); that is handled separately by BuoyancyController. Subclasses may override this to zero out DOFs that are not actuated (e.g. Z, Roll, Pitch for a 3DOF vehicle).

Parameters

velocity	[in] 6DOF body-frame velocity
acceleration	[in] 6DOF body-frame acceleration
orientation	[in] Vehicle orientation as a unit quaternion (unused in base implementation)

Returns: 6-element force/torque vector in N and Nm

Reimplemented in AsvSystemDynamics.

◆ get_m()

const Matrix6d& SystemDynamicsBase::get_m ( ) const

inline

Returns the total mass matrix M = Mrb + Ma.

◆ get_ma_matrix()

const Matrix6d& SystemDynamicsBase::get_ma_matrix ( ) const

inline

Returns the added-mass matrix Ma.

◆ get_mass_value()

double SystemDynamicsBase::get_mass_value ( ) const

inline

Returns the vehicle mass in kg.

◆ get_mrb()

const Matrix6d& SystemDynamicsBase::get_mrb ( ) const

inline

Returns the rigid-body mass matrix Mrb.

◆ get_rbb_vec()

const Vector3d& SystemDynamicsBase::get_rbb_vec ( ) const

inline

Returns the centre of buoyancy in the body frame.

◆ get_rgb_vec()

const Vector3d& SystemDynamicsBase::get_rgb_vec ( ) const

inline

Returns the centre of gravity in the body frame.

◆ get_weight()

double SystemDynamicsBase::get_weight ( ) const

inline

Returns the vehicle weight in N.

◆ set_buoyancy()

void SystemDynamicsBase::set_buoyancy ( double factor )

Sets the buoyancy force as a scale factor relative to vehicle weight.

Parameters

factor [in] Buoyancy scale factor (1.0 = neutrally buoyant)

◆ set_dl()

void SystemDynamicsBase::set_dl ( const std::array< double, 6 > & d )

Sets the diagonal linear damping coefficients.

Parameters

d	[in] Array of 6 diagonal linear damping values [Dl_x, ..., Dl_r]

◆ set_dnl()

void SystemDynamicsBase::set_dnl ( const std::array< double, 6 > & d )

Sets the diagonal quadratic (nonlinear) damping coefficients.

Parameters

d	[in] Array of 6 diagonal quadratic damping values [Dnl_x, ..., Dnl_r]

◆ set_i()

void SystemDynamicsBase::set_i ( const std::array< double, 6 > & I )

Sets the rigid-body inertia tensor.

Parameters

I	[in] Array of 6 inertia components [Ixx, Iyy, Izz, Ixy, Ixz, Iyz]

◆ set_ma()

void SystemDynamicsBase::set_ma ( const std::array< double, 6 > & m )

Sets the diagonal added-mass coefficients.

Parameters

m	[in] Array of 6 diagonal added-mass values [Ma_x, Ma_y, Ma_z, Ma_p, Ma_q, Ma_r]

◆ set_mass()

void SystemDynamicsBase::set_mass ( double m )

Sets vehicle mass and recomputes weight, buoyancy, and the rigid-body mass matrix.

The existing buoyancy-to-weight ratio is preserved when mass changes.

Parameters

m	[in] Vehicle mass in kg

◆ set_rbb()

void SystemDynamicsBase::set_rbb ( const std::array< double, 3 > & rbb )

Sets the centre-of-buoyancy position in the body frame.

Parameters

rbb	[in] Array of 3 coordinates [x, y, z] in metres

◆ set_rgb()

void SystemDynamicsBase::set_rgb ( const std::array< double, 3 > & rgb )

Sets the centre-of-gravity position in the body frame.

Parameters

rgb	[in] Array of 3 coordinates [x, y, z] in metres

Member Data Documentation

◆ is_system_3dof_

const bool SystemDynamicsBase::is_system_3dof_

True if the vehicle is constrained to the XY-Yaw plane (3DOF surface vehicle)

The documentation for this class was generated from the following files:

include/dynamics/SystemDynamicsBase.h
src/dynamics/SystemDynamicsBase.cpp

Public Member Functions

Public Attributes

Detailed Description

Constructor & Destructor Documentation

◆ SystemDynamicsBase()

◆ ~SystemDynamicsBase()

Member Function Documentation

◆ get_buoyancy_value()

◆ get_c()

◆ get_ca()

◆ get_crb()

◆ get_d()

◆ get_dl_matrix()

◆ get_dnl_matrix()

◆ get_fbn()

◆ get_fgn()

◆ get_g() [1/2]

◆ get_g() [2/2]

◆ get_inverse_dynamics()

◆ get_m()

◆ get_ma_matrix()

◆ get_mass_value()

◆ get_mrb()

◆ get_rbb_vec()

◆ get_rgb_vec()

◆ get_weight()

◆ set_buoyancy()

◆ set_dl()

◆ set_dnl()

◆ set_i()

◆ set_ma()

◆ set_mass()

◆ set_rbb()

◆ set_rgb()

Member Data Documentation

◆ is_system_3dof_