mirror of https://github.com/ArduPilot/ardupilot
93 lines
2.1 KiB
Plaintext
93 lines
2.1 KiB
Plaintext
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struct DataPoint {
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unsigned long x;
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long y;
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};
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DataPoint history[ALTITUDE_HISTORY_LENGTH]; // Collection of (x,y) points to regress a rate of change from
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unsigned char index; // Index in history for the current data point
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unsigned long xoffset;
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unsigned char n;
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// Intermediate variables for regression calculation
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long xi;
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long yi;
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long xiyi;
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unsigned long xi2;
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void add_altitude_data(unsigned long xl, long y)
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{
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unsigned char i;
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int dx;
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//Reset the regression if our X variable overflowed
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if (xl < xoffset)
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n = 0;
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//To allow calculation of sum(xi*yi), make sure X hasn't exceeded 2^32/2^15/length
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if (xl - xoffset > 131072/ALTITUDE_HISTORY_LENGTH)
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n = 0;
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if (n == ALTITUDE_HISTORY_LENGTH) {
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xi -= history[index].x;
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yi -= history[index].y;
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xiyi -= (long)history[index].x * history[index].y;
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xi2 -= history[index].x * history[index].x;
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} else {
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if (n == 0) {
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xoffset = xl;
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xi = 0;
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yi = 0;
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xiyi = 0;
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xi2 = 0;
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}
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n++;
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}
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history[index].x = xl - xoffset;
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history[index].y = y;
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xi += history[index].x;
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yi += history[index].y;
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xiyi += (long)history[index].x * history[index].y;
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xi2 += history[index].x * history[index].x;
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if (++index >= ALTITUDE_HISTORY_LENGTH)
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index = 0;
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}
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void recalc_climb_rate()
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{
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float slope = ((float)xi*(float)yi - ALTITUDE_HISTORY_LENGTH*(float)xiyi) / ((float)xi*(float)xi - ALTITUDE_HISTORY_LENGTH*(float)xi2);
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climb_rate = (int)(slope*100);
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}
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void print_climb_debug_info()
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{
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unsigned char i, j;
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recalc_climb_rate();
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SendDebugln_P("Climb rate:");
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for (i=0; i<ALTITUDE_HISTORY_LENGTH; i++) {
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j = i + index;
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if (j >= ALTITUDE_HISTORY_LENGTH) j -= ALTITUDE_HISTORY_LENGTH;
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SendDebug_P(" ");
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SendDebug(j,DEC);
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SendDebug_P(": ");
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SendDebug(history[j].x,DEC);
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SendDebug_P(", ");
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SendDebugln(history[j].y,DEC);
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}
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SendDebug_P(" sum(xi) = ");
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SendDebugln(xi,DEC);
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SendDebug_P(" sum(yi) = ");
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SendDebugln(yi,DEC);
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SendDebug_P(" sum(xi*yi) = ");
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SendDebugln(xiyi,DEC);
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SendDebug_P(" sum(xi^2) = ");
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SendDebugln(xi2,DEC);
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SendDebug_P(" Climb rate = ");
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SendDebug((float)climb_rate/100,2);
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SendDebugln_P(" m/s");
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}
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