PID3Axis Class Reference

A PID Based 3 axis controller for spacecraft. More...

List of all members.

Public Member Functions
	PID3Axis (void)
	Constructor.
void	Initialize (ml_matrix a, ml_matrix b, ml_matrix c, ml_matrix d, double angle, ml_matrix inr)
	Initialize all state matrices.
void	InitializePitch (ml_matrix a, ml_matrix b, ml_matrix c, ml_matrix d, double angle, ml_matrix inr)
	Initialize pitch matrices.
void	InitializeRoll (ml_matrix a, ml_matrix b, ml_matrix c, ml_matrix d, double angle, ml_matrix inr)
	Initialize roll matrices.
void	InitializeYaw (ml_matrix a, ml_matrix b, ml_matrix c, ml_matrix d, double angle, ml_matrix inr)
	Initialize yaw matrices.
void	AddWindupCompensation (ml_matrix l, ml_matrix saturation)
	Add windup compensation.
ml_matrix	Update (ml_matrix q_eci_to_body)
	Update the output.
void	Reset (void)
	Reset the pid.
void	SetRotateCommand (ml_matrix axis, double angle)
	Set the rotate command.
void	SetAlignCommand (ml_matrix body_vector, ml_matrix eci_vector)
	Set the align command.
void	SetAlignAndRotateCommand (ml_matrix body_vector, ml_matrix eci_vector, double angle)
	Set the align and rotate command.
void	SetInertia (ml_matrix inertia)
	Set the inertia.
void	SetDesQuat (ml_matrix qdes)
	Set the desired quaternion.
ml_matrix	GetDesQuat (void)
	Set the desired quaternion to the default.
bool	GetStatus (void)
	Get the PID status.
ml_matrix	GetInertia (void)
	Get the inertia.
void	SetMaximumDeltaAngle (double delta)
	Set the maximum delta per step.
Public Attributes
ml_matrix	q_desired_state
	Target quaternion.

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Detailed Description

A PID Based 3 axis controller for spacecraft.

Includes a limit on the max angle command allowed per update step. Uses the input inertia to compute a torque demand. Acceleration is computed for each axis independently. Supports several input formats including a desired quaternion, a rotation about an axis, and an align command. The PID is implemented as a state space controller of the form

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Member Function Documentation

void PID3Axis::Initialize	(	ml_matrix	a,
		ml_matrix	b,
		ml_matrix	c,
		ml_matrix	d,
		double	angle,
		ml_matrix	inr
	)

Initialize the class with the discrete controller gains (state space format).

Parameters:

a	Gain matrix A
b	Gain matrix B
c	Gain matrix C
d	Gain matrix D
angle	Maximum angle constraint (rad)
inr	Vehicle inertia matrix (3x3)

ml_matrix PID3Axis::Update

(

ml_matrix

q_ECI_body )

Update the controller.

Parameters:

q_ECI_body

Current vehicle orientation (4x1)

Returns:

Torque demand (3x1)

void PID3Axis::SetRotateCommand	(	ml_matrix	axis,
		double	angle
	)

Set a rotation command using an axis and angle.

Parameters:

axis	Axis in the body frame to rotate around (3x1)
angle	Angle in rad to rotate

void PID3Axis::SetAlignCommand	(	ml_matrix	body_vector,
		ml_matrix	eci_vector
	)

Set an alignment command using a body vector and an inertial vector.

Parameters:

body_vector	Axis in the body frame to align (3x1)
eci_vector	Inertial vector to align with (3x1)

void PID3Axis::SetAlignAndRotateCommand	(	ml_matrix	body_vector,
		ml_matrix	eci_vector,
		double	angle
	)

Set an alignment command and rotate using a body vector, an inertial vector and an angle about the inertial vector.

Parameters:

body_vector	Axis in the body frame to align (3x1)
eci_vector	Inertial vector to align with (3x1)
angle	Angle about inertial vector

void PID3Axis::SetDesQuat

(

ml_matrix

qdes )

Set a target quaternion.

Parameters:

qdes	The new desired quaternion (4x1)

ml_matrix PID3Axis::GetDesQuat

(

void

)

Get the target quaternion.

Returns:

The current target quaternion (4x1)

bool PID3Axis::GetStatus

(

void

)

Get the status of the controller.

Returns:

True if PID is initialized, false otherwise

ml_matrix PID3Axis::GetInertia

(

void

)

Get the inertia matrix.

Returns:

The current inertia matrix (3x3)