A interface for the the system dynamics of a legged robot. More...

#include <dynamic_model.h>

Inheritance diagram for towr::DynamicModel:

Public Types
using	AngVel = Eigen::Vector3d

using	BaseAcc = Eigen::Matrix< double, 6, 1 >

using	ComPos = Eigen::Vector3d

using	EE = uint

using	EELoad = EEPos

using	EEPos = std::vector< Eigen::Vector3d >

using	Jac = Eigen::SparseMatrix< double, Eigen::RowMajor >

using	Matrix3d = Eigen::Matrix3d

using	Ptr = std::shared_ptr< DynamicModel >

using	Vector3d = Eigen::Vector3d

Public Member Functions
double	g () const

virtual BaseAcc	GetDynamicViolation () const =0
	The violation of the system dynamics incurred by the current values. More...

int	GetEECount () const
	the number of endeffectors that this robot has. More...

virtual Jac	GetJacobianWrtBaseAng (const EulerConverter &base_angular, double t) const =0
	How the base orientation affects the dynamic violation. More...

virtual Jac	GetJacobianWrtBaseLin (const Jac &jac_base_lin_pos, const Jac &jac_base_lin_acc) const =0
	How the base position affects the dynamic violation. More...

virtual Jac	GetJacobianWrtEEPos (const Jac &ee_pos, EE ee) const =0
	How the endeffector positions affect the dynamic violation. More...

virtual Jac	GetJacobianWrtForce (const Jac &ee_force, EE ee) const =0
	How the endeffector forces affect the dynamic violation. More...

double	m () const

void	SetCurrent (const ComPos &com_W, const Vector3d com_acc_W, const Matrix3d &w_R_b, const AngVel &omega_W, const Vector3d &omega_dot_W, const EELoad &force_W, const EEPos &pos_W)
	Sets the current state and input of the system. More...

Protected Member Functions
	DynamicModel (double mass, int ee_count)
	Construct a dynamic object. Protected as this is abstract base class. More...

virtual	~DynamicModel ()=default

Protected Attributes
Vector3d	com_acc_
	x-y-z acceleration of the Center-of-Mass. More...

ComPos	com_pos_
	x-y-z position of the Center-of-Mass. More...

EELoad	ee_force_
	The endeffector force expressed in world frame. More...

EEPos	ee_pos_
	The x-y-z position of each endeffector. More...

AngVel	omega_
	angular velocity expressed in world frame. More...

Vector3d	omega_dot_
	angular acceleration expressed in world frame. More...

Matrix3d	w_R_b_
	rotation matrix from base (b) to world (w) frame. More...

Private Attributes
double	g_
	gravity acceleration [m/s^2] More...

double	m_
	mass of the robot More...

Detailed Description

A interface for the the system dynamics of a legged robot.

This class is responsible for verifying that the current acceleration of a system given a specific robot state and input forces ensure the system dynamics, so g = xdd(t) - f(x(t), f(t)).

This model is used in DynamicConstraint to ensure that the optimized motion trajectory complies to this.

Currently, only CentroidalModel is implemented, but this can be extended in the future to also incorporate full rigid body dynamics. This interface to the solver should remain the same.

Definition at line 58 of file dynamic_model.h.

Member Typedef Documentation

using towr::DynamicModel::AngVel = Eigen::Vector3d

Definition at line 64 of file dynamic_model.h.

using towr::DynamicModel::BaseAcc = Eigen::Matrix<double,6,1>

Definition at line 65 of file dynamic_model.h.

using towr::DynamicModel::ComPos = Eigen::Vector3d

Definition at line 63 of file dynamic_model.h.

using towr::DynamicModel::EE = uint

Definition at line 69 of file dynamic_model.h.

using towr::DynamicModel::EELoad = EEPos

Definition at line 68 of file dynamic_model.h.

using towr::DynamicModel::EEPos = std::vector<Eigen::Vector3d>

Definition at line 67 of file dynamic_model.h.

using towr::DynamicModel::Jac = Eigen::SparseMatrix<double, Eigen::RowMajor>

Definition at line 66 of file dynamic_model.h.

using towr::DynamicModel::Matrix3d = Eigen::Matrix3d

Definition at line 62 of file dynamic_model.h.

using towr::DynamicModel::Ptr = std::shared_ptr<DynamicModel>

Definition at line 60 of file dynamic_model.h.

using towr::DynamicModel::Vector3d = Eigen::Vector3d

Definition at line 61 of file dynamic_model.h.

Constructor & Destructor Documentation

towr::DynamicModel::DynamicModel	(	double	mass,
		int	ee_count
	)

protected

Construct a dynamic object. Protected as this is abstract base class.

Parameters

mass	The mass of the system.

Definition at line 34 of file dynamic_model.cc.

virtual towr::DynamicModel::~DynamicModel ( )

protectedvirtualdefault

Member Function Documentation

double towr::DynamicModel::g ( ) const

inline

Returns: The gravity acceleration [m/s^2] (positive)

Definition at line 136 of file dynamic_model.h.

virtual BaseAcc towr::DynamicModel::GetDynamicViolation ( ) const

pure virtual

The violation of the system dynamics incurred by the current values.

Returns: The 6-dimension generalized force violation (angular + linear).

Implemented in towr::CentroidalModel.

int towr::DynamicModel::GetEECount ( ) const

inline

the number of endeffectors that this robot has.

Definition at line 146 of file dynamic_model.h.

virtual Jac towr::DynamicModel::GetJacobianWrtBaseAng	(	const EulerConverter &	base_angular,
		double	t
	)		const

pure virtual

How the base orientation affects the dynamic violation.

Parameters

base_angular	provides Euler angles Jacobians.
t	Time at which euler angles values are queried.

Returns: The 6xn Jacobian of dynamic violations with respect to variables defining the base angular spline (e.g. node values).

Implemented in towr::CentroidalModel.

virtual Jac towr::DynamicModel::GetJacobianWrtBaseLin	(	const Jac &	jac_base_lin_pos,
		const Jac &	jac_base_lin_acc
	)		const

pure virtual

How the base position affects the dynamic violation.

Parameters

jac_base_lin_pos	The 3xn Jacobian of the base linear position.
jac_base_lin_acc	The 3xn Jacobian of the base linear acceleration.

Returns: The 6xn Jacobian of dynamic violations with respect to variables defining the base linear spline (e.g. node values).

Implemented in towr::CentroidalModel.

virtual Jac towr::DynamicModel::GetJacobianWrtEEPos	(	const Jac &	ee_pos,
		EE	ee
	)		const

pure virtual

How the endeffector positions affect the dynamic violation.

Parameters

ee_force	The 3xn Jacobian of the foot position x,y,z.
ee	The endeffector for which the senstivity is required.

Returns: The 6xn Jacobian of dynamic violations with respect to variables defining the foot positions (e.g. node values).

Implemented in towr::CentroidalModel.

virtual Jac towr::DynamicModel::GetJacobianWrtForce	(	const Jac &	ee_force,
		EE	ee
	)		const

pure virtual

How the endeffector forces affect the dynamic violation.

Parameters

ee_force	The 3xn Jacobian of the foot force x,y,z.
ee	The endeffector for which the senstivity is required.

Returns: The 6xn Jacobian of dynamic violations with respect to variables defining the endeffector forces (e.g. node values).

Implemented in towr::CentroidalModel.

double towr::DynamicModel::m ( ) const

inline

Returns: The mass of the robot [kg].

Definition at line 141 of file dynamic_model.h.

void towr::DynamicModel::SetCurrent	(	const ComPos &	com_W,
		const Vector3d	com_acc_W,
		const Matrix3d &	w_R_b,
		const AngVel &	omega_W,
		const Vector3d &	omega_dot_W,
		const EELoad &	force_W,
		const EEPos &	pos_W
	)

Sets the current state and input of the system.

Parameters

com_W	Current Center-of-Mass (x,y,z) position in world frame.
com_acc_W	Current Center-of-Mass (x,y,z) acceleration in world.
w_R_b	Current rotation from base to world frame.
omega_W	Current angular velocity in world frame.
omega_dot_W	Current angular acceleration in world frame.
force_W	Force at each foot expressed in world frame.
pos_W	Position of each foot expressed in world frame

Definition at line 51 of file dynamic_model.cc.

Member Data Documentation

Vector3d towr::DynamicModel::com_acc_

protected

x-y-z acceleration of the Center-of-Mass.

Definition at line 150 of file dynamic_model.h.

ComPos towr::DynamicModel::com_pos_

protected

x-y-z position of the Center-of-Mass.

Definition at line 146 of file dynamic_model.h.

EELoad towr::DynamicModel::ee_force_

protected

The endeffector force expressed in world frame.

Definition at line 157 of file dynamic_model.h.

EEPos towr::DynamicModel::ee_pos_

protected

The x-y-z position of each endeffector.

Definition at line 156 of file dynamic_model.h.

double towr::DynamicModel::g_

private

gravity acceleration [m/s^2]

Definition at line 167 of file dynamic_model.h.

double towr::DynamicModel::m_

private

mass of the robot

Definition at line 168 of file dynamic_model.h.

AngVel towr::DynamicModel::omega_

protected

angular velocity expressed in world frame.

Definition at line 153 of file dynamic_model.h.

Vector3d towr::DynamicModel::omega_dot_

protected

angular acceleration expressed in world frame.

Definition at line 154 of file dynamic_model.h.

Matrix3d towr::DynamicModel::w_R_b_

protected

rotation matrix from base (b) to world (w) frame.

Definition at line 152 of file dynamic_model.h.

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

Public Types

Public Member Functions

Protected Member Functions

Protected Attributes

Private Attributes

Detailed Description

Member Typedef Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation