ATT.h File Reference

LAT Attitude Processing Package. More...

#include <ATT/ATT_msg.h>
#include <PBS/WCT.h>

Typedefs
typedef struct _ATT_Control	ATT_Control
Functions
Attitude Processing Control Functions
ATT_Control *	ATT_get (void)
	Get pointer to attitude processing global handle.
unsigned int	ATT_init (ATT_Control *ctl, unsigned int numSecs)
	Initialize global attitude processing handle.
unsigned int	ATT_exit (ATT_Control *ctl)
	Shutdown the attitude processing global handle.
unsigned int	ATT_reset (ATT_Control *ctl)
	Reset the attitude processing global handle.
unsigned int	ATT_update (ATT_Control *ctl, const WCT_time t, const double *Q, const float *W)
	Update attitude history list.
unsigned int	ATT_lookup (ATT_Control *ctl, const WCT_time t, double *Q)
	Lookup attitude information in history list.
unsigned int	ATT_range (ATT_Control *ctl, WCT_time *tBottom, WCT_time *tTop)
	Get current time range of history list.
unsigned int	ATT_xform (ATT_Control *ctl, const WCT_time t, const double *Vl, double *Vj)
	Trasform a vector from LAT coordinates to J2000 coordinates.
Vector Utility Functions
void	ATT_vec_cart_to_sphr_rad (const double *Vc, double *Vs)
	Transform a cartesian vector to spherical (ra,dec) coordinates (radians).
void	ATT_vec_cart_to_sphr_deg (const double *Vc, double *Vs)
	Transform a cartesian vector to spherical (ra,dec) coordinates (degrees).
double	ATT_vec_magnitude (const double *V)
	Get a vector magnitude.
void	ATT_vec_normalize (double *V)
	Normallize a vector.
Quaternion Utility Functions
void	ATT_quat_multiply (double *Qr, const double *Qa, const double *Qb)
	Multiply two quaternions.
double	ATT_quat_magnitude (const double *Q)
	Get a quaternion magnitude.
void	ATT_quat_normalize (double *Q)
	Normallize a quaternion.
void	ATT_quat_conjugate (double *Qr, const double *Qa)
	Get a quaternion conjugate.
Vector Transform Functions
void	ATT_xform_vec_by_quat (double *Ve, const double *Q, const double *Vl)
	Tranform vector coordinates from LAT to J2000.

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Detailed Description

LAT Attitude Processing Package.

Author:

D.L. Wood

This library contains functions and definitions for manipulating and transforming vectors in LAT instrument body coordinates to vectors in J2000 coordinates. The ultimate goal is to produce a vector in J2000 coordinates (RA, DEC) for any given cartesian vector in LAT local coordinates.

The attitude information is input in the form of an attidude state vector which consists of a:

1. Timestamp as a 64-bit WCT value
2. Four element SC-J2000 attitude quaternion
3. Three element SC angular velocity vector

This information is provided to the LAT from the SC GNC system. The attitude library maintains a short time history of the attitude information to allow for vector transformations at arbitrary times in the recent past. Call the function ATT_update() to inform the attitude processing software of a new message available from the SC.

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Typedef Documentation

ATT_Control

The type for the global attitude processing control descriptor.