Chassis Class Reference

Quadruped Chassis. More...

#include <Chassis.hpp>

Public Member Functions
	Chassis (Eigen::Matrix6d &G, Eigen::Isometry3d &Ms, std::array< Eigen::Isometry3d, 4 > &M01)
	Chassis Constructor.
bool	ik (const Eigen::Isometry3d &Ts0, const std::array< Eigen::Isometry3d, 4 > &T4, std::array< Eigen::Vector3d, 4 > &pf, Eigen::Matrix< double, 6, 12 > *Jinv)
	Inverse Kinematics.
bool	ivk (const Eigen::Vector6d &Vb, const Eigen::Matrix< double, 6, 12 > &Jinv, std::array< Eigen::Vector3d, 4 > &vf)
	Inverse Velocity Kinematics.
bool	id (std::array< Eigen::Vector3d, 4 > &ff)
	Inverse Dynamics.
bool	nvp (const Eigen::Vector6d &F, const std::array< std::shared_ptr< Leg >, 4 > &legs, double &K)
	Margin of Static Stability.
void	run ()

Public Attributes
Eigen::Isometry3d	Ts0
	Tf chassis in home frame [SE(3)].
Eigen::Vector6d	Vb
	Chassis twist [rad/s; m/s].
Eigen::Vector6d	dVb
	Chassis spatial acceleration [rad/s^2; m/s^2].
Eigen::Vector6d	Fb
	Chassis wrench [N*m; m].
double	K
	Lowest normalized virtual power.
int	iRolloverLeg
	Index of leg with lowest bordering K (next leg to step).
std::array< Eigen::Isometry3d, 4 >	T4
	Tf legs in the space frame [SE(3)].
std::array< std::shared_ptr< Leg >, 4 >	legs
	Array of Leg shared pointers.
Eigen::Hyperplane< double, 3 >	footPlane
	Foot Plane.

Private Attributes
const Eigen::Matrix6d	G
	Spatial inertia matrix [kg*m^2; m].
const Eigen::Isometry3d	Ms
	Tf chassis home in the space frame [SE(3)].
const std::array< Eigen::Isometry3d, 4 >	M01
	Tf legs in the chassis body frame [SE(3)].
Eigen::Matrix< double, 6, 12 >	Jinv
	6x12 Inverse Jacobian
const Eigen::Vector3d	g {0, 0, 9.81}
	Gravity vector [m/s^2].

Detailed Description

Quadruped Chassis.

The chassis class contains gemotry and mass properties for the chassis, the chassis state, and functions to operate on the chassis state.

• {b} is the chassis "body" frame, at the volumetric center of the chassis
• {1} is the shoulder frame
• {4} is the foot frame, different for each foot

Constructor & Destructor Documentation

Chassis()

Chassis::Chassis ( Eigen::Matrix6d & G, Eigen::Isometry3d & Ms, std::array< Eigen::Isometry3d, 4 > & M01 )

inline

Chassis Constructor.

Parameters

[in]	G	6x6 spatial inertia matrix for the chassis
[in]	Ms	Home transform of the chassis in the base frame
[in]	M01	Array of transforms from the chassis frame to the leg base frames

Member Function Documentation

id()

bool Chassis::id

(

std::array< Eigen::Vector3d, 4 > &

ff

)

Inverse Dynamics.

Compute foot force from chassis state

Parameters

[out]

ff

Array of 3-vector resultant foot forces

ik()

bool Chassis::ik	(	const Eigen::Isometry3d &	Ts0,
		const std::array< Eigen::Isometry3d, 4 > &	T4,
		std::array< Eigen::Vector3d, 4 > &	pf,
		Eigen::Matrix< double, 6, 12 > *	Jinv )

Inverse Kinematics.

Compute foot poses (and Jacobian inverse) at a given chassis pose

Parameters

[in]	Ts0	SE(3) transform of the chassis in the chassis home frame
[in]	T4	Array of SE(3) transforms of the legs in the base frame
[out]	pf	Array of 3-vector resultant foot positions in the leg base frame
[out]	Jinv	6x12 resultant Jacobian inverse (dfoot/dT)

ivk()

bool Chassis::ivk	(	const Eigen::Vector6d &	Vb,
		const Eigen::Matrix< double, 6, 12 > &	Jinv,
		std::array< Eigen::Vector3d, 4 > &	vf )

Inverse Velocity Kinematics.

Compute foot velocities for a given chassis twist

Parameters

[in]	Vb	6-vector twist of the chassis body
[in]	Jinv	6x12 Jacobian inverse (dfoot/dT)
[out]	vf	Array of 3-vector resultant foot velocities

nvp()

bool Chassis::nvp	(	const Eigen::Vector6d &	F,
		const std::array< std::shared_ptr< Leg >, 4 > &	legs,
		double &	K )

Margin of Static Stability.

Compute the minimum Normalized Virtual Power required for rollover in the current state

Parameters

[in]	F	Chassis wrench in the space frame
[in]	pf	Array of 3-vector resultant foot positions in the leg base frame
[out]	K	Minimum Normalized Virtual Power

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

• include/Chassis.hpp
• src/Chassis.cpp