mirror of https://github.com/ArduPilot/ardupilot
70 lines
1.6 KiB
C++
70 lines
1.6 KiB
C++
#include "AP_Math.h"
|
|
|
|
// a varient of asin() that checks the input ranges and ensures a
|
|
// valid angle as output. If nan is given as input then zero is
|
|
// returned.
|
|
float safe_asin(float v)
|
|
{
|
|
if (isnan(v)) {
|
|
return 0.0;
|
|
}
|
|
if (v >= 1.0) {
|
|
return PI/2;
|
|
}
|
|
if (v <= -1.0) {
|
|
return -PI/2;
|
|
}
|
|
return asin(v);
|
|
}
|
|
|
|
// a varient of sqrt() that checks the input ranges and ensures a
|
|
// valid value as output. If a negative number is given then 0 is
|
|
// returned. The reasoning is that a negative number for sqrt() in our
|
|
// code is usually caused by small numerical rounding errors, so the
|
|
// real input should have been zero
|
|
float safe_sqrt(float v)
|
|
{
|
|
if (isnan(v) || v <= 0.0) {
|
|
return 0.0;
|
|
}
|
|
return sqrt(v);
|
|
}
|
|
|
|
|
|
// create a rotation matrix given some euler angles
|
|
// this is based on http://gentlenav.googlecode.com/files/EulerAngles.pdf
|
|
void rotation_matrix_from_euler(Matrix3f &m, float roll, float pitch, float yaw)
|
|
{
|
|
float cp = cos(pitch);
|
|
float sp = sin(pitch);
|
|
float sr = sin(roll);
|
|
float cr = cos(roll);
|
|
float sy = sin(yaw);
|
|
float cy = cos(yaw);
|
|
|
|
m.a.x = cp * cy;
|
|
m.a.y = (sr * sp * cy) - (cr * sy);
|
|
m.a.z = (cr * sp * cy) + (sr * sy);
|
|
m.b.x = cp * sy;
|
|
m.b.y = (sr * sp * sy) + (cr * cy);
|
|
m.b.z = (cr * sp * sy) - (sr * cy);
|
|
m.c.x = -sp;
|
|
m.c.y = sr * cp;
|
|
m.c.z = cr * cp;
|
|
}
|
|
|
|
// calculate euler angles from a rotation matrix
|
|
// this is based on http://gentlenav.googlecode.com/files/EulerAngles.pdf
|
|
void calculate_euler_angles(Matrix3f &m, float *roll, float *pitch, float *yaw)
|
|
{
|
|
if (pitch != NULL) {
|
|
*pitch = -safe_asin(m.c.x);
|
|
}
|
|
if (roll != NULL) {
|
|
*roll = atan2(m.c.y, m.c.z);
|
|
}
|
|
if (yaw != NULL) {
|
|
*yaw = atan2(m.b.x, m.a.x);
|
|
}
|
|
}
|