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# # old_revision [4cc7246c1b6c809c9dc15997798f6deed15b3631] # new_revision [be147b11caac304fda1579ac71017eecc3bb79e0] # # patch "dcm.c" # from [16b59bc009e1e04c2932e132fa351a06fa789e3a] # to [90d94d47a262c72d472ee7aca36bb55e2b328e66] # ============================================================ --- dcm.c 16b59bc009e1e04c2932e132fa351a06fa789e3a +++ dcm.c 90d94d47a262c72d472ee7aca36bb55e2b328e66 @@ -2,11 +2,27 @@ #ifdef WE_HAVE_SQRT #include <math.h> +#else +#include "fisqrt.h" #endif #include "matrix.h" #include "dcm.h" #include "uart.h" +#include "motor.h" +#include "status.h" +#include "abs.h" +#define GRAVITY 9.80665f + +#define KP_ROLLPITCH 0.05967 +#define KI_ROLLPITCH 0.00001278 + +#define ERROR_LIMIT 1.17f + +/* Maximum allowed error for arming */ +#define ERROR_THRESHOLD 0.20f + + /* Implementation of the DCM IMU concept as described by Premerlani * and Bizard */ @@ -15,10 +31,19 @@ float dcm[3*3] = {1, 0, 0, 0, 1, 0, 0, 0, 1}; +float omega_p[3] = {0.0, 0.0, 0.0}; +float omega_i[3] = {0.0, 0.0, 0.0}; + +float omega_x, omega_y, omega_z; + float delta_t = 0.01; -void dcm_update(float omega_x, float omega_y, float omega_z) +void dcm_update(float x, float y, float z) { + omega_x = x + omega_i[0] + omega_p[0]; + omega_y = y + omega_i[1] + omega_p[1]; + omega_z = z + omega_i[2] + omega_p[2]; + float tx = delta_t * omega_x; float ty = delta_t * omega_y; float tz = delta_t * omega_z; @@ -34,6 +59,36 @@ void dcm_update(float omega_x, float ome dcm_normalise(); } +void dcm_setvector(float x, float y, float z) +{ + /* We're given the Z axis */ + dcm[6] = x; + dcm[7] = y; + dcm[8] = z; + + /* Second row = cross product of unit X and third rows */ + dcm[3] = 0.0; + dcm[4] = -dcm[8]; + dcm[5] = dcm[7]; + + /* First row = cross product of third and second rows */ + dcm[0] = dcm[7]*dcm[5] - dcm[8]*dcm[4]; + dcm[1] = dcm[8]*dcm[3] - dcm[6]*dcm[5]; + dcm[2] = dcm[6]*dcm[4] - dcm[7]*dcm[3]; + + /* Second row = cross product of third and first rows */ + dcm[3] = dcm[7]*dcm[2] - dcm[8]*dcm[1]; + dcm[4] = dcm[8]*dcm[0] - dcm[6]*dcm[2]; + dcm[5] = dcm[6]*dcm[1] - dcm[7]*dcm[0]; + + dcm_renormalise(dcm+0); + dcm_renormalise(dcm+3); + dcm_renormalise(dcm+6); +#if 0 + dcm_normalise(); +#endif +} + void dcm_normalise(void) { float error; @@ -78,11 +133,14 @@ bool dcm_renormalise(float *v) if (f < 1.5625f && f > 0.64f) { f = 0.5 * (3 - f); + } else if (f < 100.0f && f > 0.01f) { #ifdef WE_HAVE_SQRT - } else if (f < 100.0f && f > 0.01f) { f = 1.0 / sqrt(f); - /* XXX log this event? */ +#else + f = fisqrt(f); #endif + /* XXX log this event? */ + putstr("sqrt\r\n"); } else { putstr("problem\r\n"); return FALSE; @@ -95,6 +153,103 @@ bool dcm_renormalise(float *v) return TRUE; } +void dcm_drift_correction(float x, float y, float z) +{ + float mag; + float weight; + float error[3]; + int i; + + mag = (1.0/fisqrt(x*x+y*y+z*z)) / GRAVITY; + + mag = 1-mag; + if (mag < 0.0) + mag = -mag; + + weight = 1 - 3*mag; + + if (weight < 0.0) + weight = 0.0; + if (weight > 1.0) + weight = 1.0; + + /* error = cross product of dcm last row and acceleration vector */ + /* third row = cross product of first two rows */ + error[0] = dcm[7]*z - dcm[8]*y; + error[1] = dcm[8]*x - dcm[6]*z; + error[2] = dcm[6]*y - dcm[7]*x; + + if (!status_armed()) { + if ((abs(error[0]) < ERROR_THRESHOLD) && + (abs(error[1]) < ERROR_THRESHOLD) && + (abs(error[2]) < ERROR_THRESHOLD)) + status_set_ready(STATUS_MODULE_DCM_ERROR, TRUE); + else + status_set_ready(STATUS_MODULE_DCM_ERROR, FALSE); + } + + for (i = 0; i < 3; i++) { + if (error[i] > ERROR_LIMIT) + error[i] = ERROR_LIMIT; + if (error[i] < -ERROR_LIMIT) + error[i] = -ERROR_LIMIT; + } + + for (i = 0; i < 3; i++) { + omega_p[i] = error[i] * (KP_ROLLPITCH * weight); + omega_i[i] += error[i] * (KI_ROLLPITCH * weight); + } + +#if 0 + putstr("w: "); + putint_s((int)(weight * 100000.0f)); + putstr("\r\n"); +#endif + +#if 0 + putstr("p: "); + putint_s((int)(omega_p[0] * 100000.0f)); + putstr(", "); + putint_s((int)(omega_p[1] * 100000.0f)); + putstr(", "); + putint_s((int)(omega_p[2] * 100000.0f)); + putstr(" i: "); + putint_s((int)(omega_i[0] * 100000.0f)); + putstr(", "); + putint_s((int)(omega_i[1] * 100000.0f)); + putstr(", "); + putint_s((int)(omega_i[2] * 100000.0f)); + putstr("\r\n"); +#endif +} + +/* Maximum angle to the horizontal for arming: 30 degrees */ +#define ATTITUDE_THRESHOLD (0.5) + +void dcm_attitude_error(float roll, float pitch, float yaw) +{ + /* dcm[6] = sine of pitch */ + /* dcm[7] = sine of roll */ + + /* pitch error = pitch - dcm[6] */ + /* roll error = roll - dcm[7] */ + + /* That was the theory. In practice, there appears to be some + confusion over axes. Pitch and roll seem.. reversed. */ + + /* TODO: What if we are upside down? */ + + if (!status_armed()) { + if ((abs(dcm[6]) < ATTITUDE_THRESHOLD) && + (abs(dcm[7]) < ATTITUDE_THRESHOLD)) + status_set_ready(STATUS_MODULE_ATTITUDE, TRUE); + else + status_set_ready(STATUS_MODULE_ATTITUDE, FALSE); + } + + motor_pid_update(roll, dcm[6], pitch, -dcm[7], yaw, -omega_z); +} + void dcm_dump(void) { putstr("dcm: ");