Represents a chain or tree of robot elements (rigid bodies and joints). More...

#include <robot_model.hpp>

Public Types
using	ActuatorType = robot_model::ActuatorType

using	BracketType = robot_model::BracketType

using	LinkType = robot_model::LinkType

Public Member Functions
	RobotModel ()
	Creates a robot model object with no bodies and an identity base frame. More...

std::unique_ptr< RobotModel >	createSubtree (size_t element_index)
	Create a RobotModel object that is a subtree of this robot model, beginning at a given element. The created subtree is linked to the original RobotModel, and so kinematics and IK operations are not safe if the original model and subtree are accessed from different threads. However, the lifetimes can be treated as independent (the original RobotModel can be disposed of while the subtree is still in use). More...

	~RobotModel () noexcept
	Destructor cleans up robot model object, including all managed elements. More...

void	setBaseFrame (const Eigen::Matrix4d &base_frame)
	Set the transform from a world coordinate system to the input of the root element in this robot model object. Defaults to an identity 4x4 matrix. More...

Eigen::Matrix4d	getBaseFrame () const
	Returns the transform from the world coordinate system to the root kinematic body, as set by the setBaseFrame function. More...

size_t	getFrameCount (FrameType frame_type) const
	Return the number of frames in the forward kinematics. More...

size_t	getFrameCount (HebiFrameType frame_type) const
	Return the number of frames in the forward kinematics. More...

size_t	getDoFCount () const
	Returns the number of settable degrees of freedom in the kinematic tree. (This is equal to the number of actuators added). More...

std::string	getMeshPath (size_t mesh_frame_index) const
	Returns the path to the mesh used in the "ith" mesh frame. More...

bool	addRigidBody (const Eigen::Matrix4d &com, const Eigen::VectorXd &inertia, double mass, const Eigen::Matrix4d &output)
	Adds a rigid body with the specified properties to the robot model. More...

bool	addJoint (JointType joint_type)
	Adds a degree of freedom about the specified axis. More...

bool	addJoint (HebiJointType joint_type)
	Adds a degree of freedom about the specified axis. More...

bool	addActuator (robot_model::ActuatorType actuator_type)
	Add an element to the robot model with the kinematics/dynamics of an X5 actuator. More...

bool	addLink (robot_model::LinkType link_type, double extension, double twist, LinkInputType input_type=LinkInputType::RightAngle, LinkOutputType output_type=LinkOutputType::RightAngle)
	Add an element to the robot model with the kinematics/dynamics of a link between two actuators. More...

bool	addBracket (robot_model::BracketType bracket_type)
	Add an element to the robot model with the kinematics/dynamics of a bracket between two actuators. More...

bool	addEndEffector (EndEffectorType end_effector_type)
	Add an end effector element to the robot model. More...

bool	addEndEffector (double x, double y, double z)
	Add an end effector element to the robot model. More...

bool	addEndEffector (const Eigen::Matrix4d &com, const Eigen::VectorXd &inertia, double mass, const Eigen::Matrix4d &output)
	Adds a "custom" type end effector with the specified properties to the robot model. More...

void	getForwardKinematics (FrameType, const Eigen::VectorXd &positions, Matrix4dVector &frames) const
	Generates the forward kinematics for the given robot model. More...

void	getForwardKinematics (HebiFrameType frame_type, const Eigen::VectorXd &positions, Matrix4dVector &frames) const
	Generates the forward kinematics for the given robot model. More...

void	getFK (FrameType, const Eigen::VectorXd &positions, Matrix4dVector &frames) const
	Generates the forward kinematics for the given robot model. More...

void	getFK (HebiFrameType frame_type, const Eigen::VectorXd &positions, Matrix4dVector &frames) const
	Generates the forward kinematics for the given robot model. More...

void	getEndEffector (const Eigen::VectorXd &positions, Eigen::Matrix4d &transform) const
	Generates the forward kinematics to the end effector (leaf node) frame(s). More...

template<typename... Args>
IKResult	solveInverseKinematics (const Eigen::VectorXd &initial_positions, Eigen::VectorXd &result, const Args &... args) const
	Solves for an inverse kinematics solution given a set of objectives. More...

template<typename... Args>
IKResult	solveIK (const Eigen::VectorXd &initial_positions, Eigen::VectorXd &result, const Args &... objectives) const
	Solves for an inverse kinematics solution given a set of objectives. More...

void	getJacobians (FrameType, const Eigen::VectorXd &positions, MatrixXdVector &jacobians) const
	Generates the Jacobian for each frame in the given kinematic tree. More...

void	getJacobians (HebiFrameType frame_type, const Eigen::VectorXd &positions, MatrixXdVector &jacobians) const
	Generates the Jacobian for each frame in the given kinematic tree. More...

void	getJ (FrameType, const Eigen::VectorXd &positions, MatrixXdVector &jacobians) const
	Generates the Jacobian for each frame in the given kinematic tree. More...

void	getJ (HebiFrameType frame_type, const Eigen::VectorXd &positions, MatrixXdVector &jacobians) const
	Generates the Jacobian for each frame in the given kinematic tree. More...

void	getJacobianEndEffector (const Eigen::VectorXd &positions, Eigen::MatrixXd &jacobian) const
	Generates the Jacobian for the end effector (leaf node) frames(s). More...

void	getJEndEffector (const Eigen::VectorXd &positions, Eigen::MatrixXd &jacobian) const
	Generates the Jacobian for the end effector (leaf node) frames(s). More...

void	getMasses (Eigen::VectorXd &masses) const
	Returns the mass of each rigid body (or combination of rigid bodies) in the robot model. More...

void	getMetadata (std::vector< MetadataBase > &metadata) const
	Returns the metadata of each component of the robot model. More...

void	getGravCompEfforts (const Eigen::VectorXd &angles, const Eigen::Vector3d &gravity, Eigen::VectorXd &comp_torque) const

Static Public Member Functions
static std::unique_ptr< RobotModel >	loadHRDF (const std::string &file)
	Creates a robot model object from the content of the HRDF file. More...

static std::unique_ptr< RobotModel >	loadHRDFString (const std::string &string)
	Creates a robot model object from the content of the HRDF description in the string. More...

Detailed Description

Represents a chain or tree of robot elements (rigid bodies and joints).

(Currently, only chains of elements are fully supported)

Member Typedef Documentation

◆ ActuatorType

using hebi::robot_model::RobotModel::ActuatorType = robot_model::ActuatorType

◆ BracketType

using hebi::robot_model::RobotModel::BracketType = robot_model::BracketType

◆ LinkType

using hebi::robot_model::RobotModel::LinkType = robot_model::LinkType

Constructor & Destructor Documentation

◆ RobotModel()

hebi::robot_model::RobotModel::RobotModel ( )

Creates a robot model object with no bodies and an identity base frame.

◆ ~RobotModel()

hebi::robot_model::RobotModel::~RobotModel ( )

noexcept

Destructor cleans up robot model object, including all managed elements.

Member Function Documentation

◆ loadHRDF()

std::unique_ptr< RobotModel > hebi::robot_model::RobotModel::loadHRDF ( const std::string & file )

static

Creates a robot model object from the content of the HRDF file.

◆ loadHRDFString()

std::unique_ptr< RobotModel > hebi::robot_model::RobotModel::loadHRDFString ( const std::string & string )

static

Creates a robot model object from the content of the HRDF description in the string.

◆ createSubtree()

std::unique_ptr< RobotModel > hebi::robot_model::RobotModel::createSubtree ( size_t element_index )

Create a RobotModel object that is a subtree of this robot model, beginning at a given element. The created subtree is linked to the original RobotModel, and so kinematics and IK operations are not safe if the original model and subtree are accessed from different threads. However, the lifetimes can be treated as independent (the original RobotModel can be disposed of while the subtree is still in use).

Parameters

element_index The index of the RobotMOdelElement, using a depth-first tree traversal, of the element that becomes the root of the new robot model object

Returns: A unique_ptr-wrapped RobotModel object is returned, represending a substree starting at the given index, or an empty unique_ptr if the element index is invalid for this robot model.

◆ setBaseFrame()

void hebi::robot_model::RobotModel::setBaseFrame ( const Eigen::Matrix4d & base_frame )

Set the transform from a world coordinate system to the input of the root element in this robot model object. Defaults to an identity 4x4 matrix.

The world coordinate system is used for all position, vector, and transformation matrix parameters in the member functions.

Parameters

base_frame The 4x4 homogeneous transform from the world frame to the root kinematic body frame.

◆ getBaseFrame()

Eigen::Matrix4d hebi::robot_model::RobotModel::getBaseFrame ( ) const

Returns the transform from the world coordinate system to the root kinematic body, as set by the setBaseFrame function.

◆ getFrameCount() [1/2]

size_t hebi::robot_model::RobotModel::getFrameCount ( FrameType frame_type ) const

Return the number of frames in the forward kinematics.

Note that this depends on the type of frame requested – for center of mass frames, there is one per added body; for output frames, there is one per output per body.

Parameters

frame_type Which type of frame to consider – see HebiFrameType enum.

◆ getFrameCount() [2/2]

size_t hebi::robot_model::RobotModel::getFrameCount ( HebiFrameType frame_type ) const

inline

Return the number of frames in the forward kinematics.

Deprecated:: Replaced by getFrameCount(FrameType) accepting C++ enum

◆ getDoFCount()

size_t hebi::robot_model::RobotModel::getDoFCount ( ) const

Returns the number of settable degrees of freedom in the kinematic tree. (This is equal to the number of actuators added).

◆ getMeshPath()

std::string hebi::robot_model::RobotModel::getMeshPath ( size_t mesh_frame_index ) const

Returns the path to the mesh used in the "ith" mesh frame.

Note that this may be an empty string for frames without a custom mesh, even if those frames have a mesh transform. For built-in elements with known meshes (e.g., a bracket or an R-series actuator), this currently returns an empty string, but this behavior may change in the future and should not be relied upon.

◆ addRigidBody()

bool hebi::robot_model::RobotModel::addRigidBody	(	const Eigen::Matrix4d &	com,
		const Eigen::VectorXd &	inertia,
		double	mass,
		const Eigen::Matrix4d &	output
	)

Adds a rigid body with the specified properties to the robot model.

Parameters

com	4x4 matrix of the homogeneous transform to the center of mass location, relative to the input frame of the element. Note that this frame is also the frame the inertia tensor is given in.
inertia	The 6 element representation (Ixx, Iyy, Izz, Ixy, Ixz, Iyz) of the inertia tensor, in the frame given by the COM.
output	4x4 matrix of the homogeneous transform to the output frame, relative to the input frame of the element.
mass	The mass of this element.

◆ addJoint() [1/2]

bool hebi::robot_model::RobotModel::addJoint ( JointType joint_type )

Adds a degree of freedom about the specified axis.

This does not represent an element with size or mass, but only a connection between two other elements about a particular axis.

Parameters

joint_type The axis of rotation or translation about which this joint allows motion.

◆ addJoint() [2/2]

bool hebi::robot_model::RobotModel::addJoint ( HebiJointType joint_type )

inline

Adds a degree of freedom about the specified axis.

Deprecated:: Replaced by addJoint(JointType) accepting C++ enum

◆ addActuator()

bool hebi::robot_model::RobotModel::addActuator ( robot_model::ActuatorType actuator_type )

Add an element to the robot model with the kinematics/dynamics of an X5 actuator.

Parameters

actuator_type The type of actuator to add.

◆ addLink()

bool hebi::robot_model::RobotModel::addLink	(	robot_model::LinkType	link_type,
		double	extension,
		double	twist,
		LinkInputType	input_type = `LinkInputType::RightAngle`,
		LinkOutputType	output_type = `LinkOutputType::RightAngle`
	)

Add an element to the robot model with the kinematics/dynamics of a link between two actuators.

Parameters

link_type	The type of link between the actuators, e.g. a tube link between two X5 or X8 actuators.
extension	The center-to-center distance between the actuator rotational axes.
twist	The rotation (in radians) between the actuator axes of rotation. Note that a 0 radian rotation will result in a z-axis offset between the two actuators, and a pi radian rotation will result in the actuator interfaces to this tube being in the same plane, but the rotational axes being anti-parallel.
input_type	The style of input adapter on the link.
output_type	The style of input adapter on the link.

◆ addBracket()

bool hebi::robot_model::RobotModel::addBracket ( robot_model::BracketType bracket_type )

Add an element to the robot model with the kinematics/dynamics of a bracket between two actuators.

Parameters

bracket_type The type of bracket to add.

◆ addEndEffector() [1/3]

bool hebi::robot_model::RobotModel::addEndEffector ( EndEffectorType end_effector_type )

Add an end effector element to the robot model.

For a "custom" type end effector, indentity transforms and zero mass and inertia parameters are used.

Parameters

end_effector_type The type of end_effector to add.

◆ addEndEffector() [2/3]

bool hebi::robot_model::RobotModel::addEndEffector	(	double	x,
		double	y,
		double	z
	)

Add an end effector element to the robot model.

For a "custom" type end effector, indentity transforms and zero mass and inertia parameters are used.

Parameters

frame The frame of the output of the end effector

◆ addEndEffector() [3/3]

bool hebi::robot_model::RobotModel::addEndEffector	(	const Eigen::Matrix4d &	com,
		const Eigen::VectorXd &	inertia,
		double	mass,
		const Eigen::Matrix4d &	output
	)

Adds a "custom" type end effector with the specified properties to the robot model.

Parameters

com	4x4 matrix of the homogeneous transform to the center of mass location, relative to the input frame of the element. Note that this frame is also the frame the inertia tensor is given in.
inertia	The 6 element representation (Ixx, Iyy, Izz, Ixy, Ixz, Iyz) of the inertia tensor, in the frame given by the COM.
output	4x4 matrix of the homogeneous transform to the output frame, relative to the input frame of the element.
mass	The mass of this element.

◆ getForwardKinematics() [1/2]

void hebi::robot_model::RobotModel::getForwardKinematics	(	FrameType	frame_type,
		const Eigen::VectorXd &	positions,
		Matrix4dVector &	frames
	)		const

Generates the forward kinematics for the given robot model.

See getFK for details.

◆ getForwardKinematics() [2/2]

void hebi::robot_model::RobotModel::getForwardKinematics	(	HebiFrameType	frame_type,
		const Eigen::VectorXd &	positions,
		Matrix4dVector &	frames
	)		const

inline

Generates the forward kinematics for the given robot model.

Deprecated:: Replaced by getForwardKinematics accepting C++ enum

◆ getFK() [1/2]

void hebi::robot_model::RobotModel::getFK	(	FrameType	frame_type,
		const Eigen::VectorXd &	positions,
		Matrix4dVector &	frames
	)		const

Generates the forward kinematics for the given robot model.

The order of the returned frames is in a depth-first tree. As an example, assume a body A has one output, to which body B is connected to. Body B has two outputs; actuator C is attached to the first output and actuator E is attached to the second output. Body D is attached to the only output of actuator C:

(BASE) A - B(1) - C - D (2) | E

For center of mass frames, the returned frames would be A-B-C-D-E.

For output frames, the returned frames would be A-B(1)-C-D-B(2)-E.

Parameters

frame_type	Which type of frame to consider – see FrameType enum.
positions	A vector of joint positions/angles (in SI units of meters or radians) equal in length to the number of DoFs of the kinematic tree.
frames	An array of 4x4 transforms; this is resized as necessary in the function and filled in with the 4x4 homogeneous transform of each frame. Note that the number of frames depends on the frame type.

◆ getFK() [2/2]

void hebi::robot_model::RobotModel::getFK	(	HebiFrameType	frame_type,
		const Eigen::VectorXd &	positions,
		Matrix4dVector &	frames
	)		const

inline

Generates the forward kinematics for the given robot model.

Deprecated:: Replaced by getFK accepting C++ enum

◆ getEndEffector()

void hebi::robot_model::RobotModel::getEndEffector	(	const Eigen::VectorXd &	positions,
		Eigen::Matrix4d &	transform
	)		const

Generates the forward kinematics to the end effector (leaf node) frame(s).

Note – for center of mass frames, this is one per leaf node; for output frames, this is one per output per leaf node, in depth first order.

This overload is for kinematic chains that only have a single leaf node frame.

(Currently, kinematic trees are not fully supported – only kinematic chains – and so there are not other overloads for this function).

Parameters

positions	A vector of joint positions/angles (in SI units of meters or radians) equal in length to the number of DoFs of the kinematic tree.
transform	A 4x4 transform that is resized as necessary in the function and filled in with the homogeneous transform to the end effector frame.

◆ solveInverseKinematics()

template<typename... Args>

IKResult hebi::robot_model::RobotModel::solveInverseKinematics	(	const Eigen::VectorXd &	initial_positions,
		Eigen::VectorXd &	result,
		const Args &...	args
	)		const

inline

Solves for an inverse kinematics solution given a set of objectives.

See solveIK for details.

◆ solveIK()

template<typename... Args>

IKResult hebi::robot_model::RobotModel::solveIK	(	const Eigen::VectorXd &	initial_positions,
		Eigen::VectorXd &	result,
		const Args &...	objectives
	)		const

inline

Solves for an inverse kinematics solution given a set of objectives.

Parameters

initial_positions	The seed positions/angles (in SI units of meters or radians) to start the IK search from; equal in length to the number of DoFs of the kinematic tree.
result	A vector equal in length to the number of DoFs of the kinematic tree; this will be filled in with the IK solution (in SI units of meters or radians), and resized as necessary.
objectives	A variable number of objectives used to define the IK search (e.g., target end effector positions, etc). Each argument must have a base class of Objective.

◆ getJacobians() [1/2]

void hebi::robot_model::RobotModel::getJacobians	(	FrameType	frame_type,
		const Eigen::VectorXd &	positions,
		MatrixXdVector &	jacobians
	)		const

Generates the Jacobian for each frame in the given kinematic tree.

See getJ for details.

◆ getJacobians() [2/2]

void hebi::robot_model::RobotModel::getJacobians	(	HebiFrameType	frame_type,
		const Eigen::VectorXd &	positions,
		MatrixXdVector &	jacobians
	)		const

inline

Generates the Jacobian for each frame in the given kinematic tree.

Deprecated:: Replaced by getJacobians accepting C++ enum

◆ getJ() [1/2]

void hebi::robot_model::RobotModel::getJ	(	FrameType	frame_type,
		const Eigen::VectorXd &	positions,
		MatrixXdVector &	jacobians
	)		const

Generates the Jacobian for each frame in the given kinematic tree.

Parameters

frame_type	Which type of frame to consider – see FrameType enum.
positions	A vector of joint positions/angles (in SI units of meters or radians) equal in length to the number of DoFs of the kinematic tree.
jacobians	A vector (length equal to the number of frames) of matrices; each matrix is a (6 x number of dofs) jacobian matrix for the corresponding frame of reference on the robot. This vector is resized as necessary inside this function.

◆ getJ() [2/2]

void hebi::robot_model::RobotModel::getJ	(	HebiFrameType	frame_type,
		const Eigen::VectorXd &	positions,
		MatrixXdVector &	jacobians
	)		const

inline

Generates the Jacobian for each frame in the given kinematic tree.

Deprecated:: Replaced by getJ accepting C++ enum

◆ getJacobianEndEffector()

void hebi::robot_model::RobotModel::getJacobianEndEffector	(	const Eigen::VectorXd &	positions,
		Eigen::MatrixXd &	jacobian
	)		const

Generates the Jacobian for the end effector (leaf node) frames(s).

See getJEndEffector for details.

◆ getJEndEffector()

void hebi::robot_model::RobotModel::getJEndEffector	(	const Eigen::VectorXd &	positions,
		Eigen::MatrixXd &	jacobian
	)		const

Generates the Jacobian for the end effector (leaf node) frames(s).

Note – for center of mass frames, this is one per leaf node; for output frames, this is one per output per leaf node, in depth first order.

This overload is for kinematic chains that only have a single leaf node frame.

(Currently, kinematic trees are not fully supported – only kinematic chains – and so there are not other overloads for this function).

Parameters

positions	A vector of joint positions/angles (in SI units of meters or radians) equal in length to the number of DoFs of the kinematic tree.
jacobian	A (6 x number of dofs) jacobian matrix for the corresponding end effector frame of reference on the robot. This vector is resized as necessary inside this function.

◆ getMasses()

void hebi::robot_model::RobotModel::getMasses ( Eigen::VectorXd & masses ) const

Returns the mass of each rigid body (or combination of rigid bodies) in the robot model.

Parameters

masses A vector which is filled with the masses in the robot model. This vector is resized as necessary inside this function (it is set to have length equal to the number of com frames).

◆ getMetadata()

void hebi::robot_model::RobotModel::getMetadata ( std::vector< MetadataBase > & metadata ) const

Returns the metadata of each component of the robot model.

◆ getGravCompEfforts()

void hebi::robot_model::RobotModel::getGravCompEfforts	(	const Eigen::VectorXd &	angles,
		const Eigen::Vector3d &	gravity,
		Eigen::VectorXd &	comp_torque
	)		const

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

Public Types

Public Member Functions

Static Public Member Functions

Detailed Description

Member Typedef Documentation

◆ ActuatorType

◆ BracketType

◆ LinkType

Constructor & Destructor Documentation

◆ RobotModel()

◆ ~RobotModel()

Member Function Documentation

◆ loadHRDF()

◆ loadHRDFString()

◆ createSubtree()

◆ setBaseFrame()

◆ getBaseFrame()

◆ getFrameCount() [1/2]

◆ getFrameCount() [2/2]

◆ getDoFCount()

◆ getMeshPath()

◆ addRigidBody()

◆ addJoint() [1/2]

◆ addJoint() [2/2]

◆ addActuator()

◆ addLink()

◆ addBracket()

◆ addEndEffector() [1/3]

◆ addEndEffector() [2/3]

◆ addEndEffector() [3/3]

◆ getForwardKinematics() [1/2]

◆ getForwardKinematics() [2/2]

◆ getFK() [1/2]

◆ getFK() [2/2]

◆ getEndEffector()

◆ solveInverseKinematics()

◆ solveIK()

◆ getJacobians() [1/2]

◆ getJacobians() [2/2]

◆ getJ() [1/2]

◆ getJ() [2/2]

◆ getJacobianEndEffector()

◆ getJEndEffector()

◆ getMasses()

◆ getMetadata()

◆ getGravCompEfforts()