/* * Copyright © 2009 Keith Packard * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2 of the License. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ #ifndef AO_FLIGHT_TEST #include "ao.h" #endif #ifndef HAS_ACCEL #error Please define HAS_ACCEL #endif #ifndef HAS_GPS #error Please define HAS_GPS #endif #ifndef HAS_USB #error Please define HAS_USB #endif /* Main flight thread. */ __pdata enum ao_flight_state ao_flight_state; /* current flight state */ __pdata uint16_t ao_flight_tick; /* time of last data */ __pdata uint16_t ao_flight_prev_tick; /* time of previous data */ __xdata int16_t ao_ground_pres; /* startup pressure */ __pdata uint16_t ao_launch_tick; /* time of launch detect */ #if HAS_ACCEL __pdata int16_t ao_ground_accel; /* startup acceleration */ #endif /* * track min/max data over a long interval to detect * resting */ __pdata uint16_t ao_interval_end; __pdata int16_t ao_interval_min_height; __pdata int16_t ao_interval_max_height; __data uint8_t ao_flight_adc; __pdata int16_t ao_raw_pres; __xdata uint8_t ao_flight_force_idle; #if HAS_ACCEL __pdata int16_t ao_raw_accel, ao_raw_accel_prev; __pdata int16_t ao_accel_2g; /* Accelerometer calibration * * We're sampling the accelerometer through a resistor divider which * consists of 5k and 10k resistors. This multiplies the values by 2/3. * That goes into the cc1111 A/D converter, which is running at 11 bits * of precision with the bits in the MSB of the 16 bit value. Only positive * values are used, so values should range from 0-32752 for 0-3.3V. The * specs say we should see 40mV/g (uncalibrated), multiply by 2/3 for what * the A/D converter sees (26.67 mV/g). We should see 32752/3300 counts/mV, * for a final computation of: * * 26.67 mV/g * 32767/3300 counts/mV = 264.8 counts/g * * Zero g was measured at 16000 (we would expect 16384). * Note that this value is only require to tell if the * rocket is standing upright. Once that is determined, * the value of the accelerometer is averaged for 100 samples * to find the resting accelerometer value, which is used * for all further flight computations */ #define GRAVITY 9.80665 #define ACCEL_NOSE_UP (ao_accel_2g >> 2) #endif /* * Barometer calibration * * We directly sample the barometer. The specs say: * * Pressure range: 15-115 kPa * Voltage at 115kPa: 2.82 * Output scale: 27mV/kPa * * If we want to detect launch with the barometer, we need * a large enough bump to not be fooled by noise. At typical * launch elevations (0-2000m), a 200Pa pressure change cooresponds * to about a 20m elevation change. This is 5.4mV, or about 3LSB. * As all of our calculations are done in 16 bits, we'll actually see a change * of 16 times this though * * 27 mV/kPa * 32767 / 3300 counts/mV = 268.1 counts/kPa */ /* We also have a clock, which can be used to sanity check things in * case of other failures */ #define BOOST_TICKS_MAX AO_SEC_TO_TICKS(15) #define to_fix16(x) ((int16_t) ((x) * 65536.0 + 0.5)) #define to_fix32(x) ((int32_t) ((x) * 65536.0 + 0.5)) #define from_fix(x) ((x) >> 16) #include "ao_kalman.h" __pdata int16_t ao_ground_height; __pdata int16_t ao_height; __pdata int16_t ao_speed; __pdata int16_t ao_accel; __pdata int16_t ao_max_height; static __pdata int32_t ao_k_height; static __pdata int32_t ao_k_speed; static __pdata int32_t ao_k_accel; #define AO_K_STEP_100 to_fix16(0.01) #define AO_K_STEP_2_2_100 to_fix16(0.00005) #define AO_K_STEP_10 to_fix16(0.1) #define AO_K_STEP_2_2_10 to_fix16(0.005) /* * Above this height, the baro sensor doesn't work */ #define AO_MAX_BARO_HEIGHT 12000 /* * Above this speed, baro measurements are unreliable */ #define AO_MAX_BARO_SPEED 200 static void ao_kalman_predict(void) { #ifdef AO_FLIGHT_TEST if (ao_flight_tick - ao_flight_prev_tick > 5) { ao_k_height += ((int32_t) ao_speed * AO_K_STEP_10 + (int32_t) ao_accel * AO_K_STEP_2_2_10) >> 4; ao_k_speed += (int32_t) ao_accel * AO_K_STEP_10; return; } if (ao_flight_debug) { printf ("predict speed %g + (%g * %g) = %g\n", ao_k_speed / (65536.0 * 16.0), ao_accel / 16.0, AO_K_STEP_100 / 65536.0, (ao_k_speed + (int32_t) ao_accel * AO_K_STEP_100) / (65536.0 * 16.0)); } #endif ao_k_height += ((int32_t) ao_speed * AO_K_STEP_100 + (int32_t) ao_accel * AO_K_STEP_2_2_100) >> 4; ao_k_speed += (int32_t) ao_accel * AO_K_STEP_100; } static __pdata int16_t ao_error_h; static __pdata int16_t ao_raw_alt; static __pdata int16_t ao_raw_height; static __pdata int16_t ao_error_h_sq_avg; static void ao_kalman_err_height(void) { int16_t e; int16_t height_distrust; #if HAS_ACCEL int16_t speed_distrust; #endif ao_error_h = ao_raw_height - (int16_t) (ao_k_height >> 16); e = ao_error_h; if (e < 0) e = -e; if (e > 127) e = 127; #if HAS_ACCEL ao_error_h_sq_avg -= ao_error_h_sq_avg >> 2; ao_error_h_sq_avg += (e * e) >> 2; #else ao_error_h_sq_avg -= ao_error_h_sq_avg >> 4; ao_error_h_sq_avg += (e * e) >> 4; #endif height_distrust = ao_raw_height - AO_MAX_BARO_HEIGHT; #if HAS_ACCEL /* speed is stored * 16, but we need to ramp between 200 and 328, so * we want to multiply by 2. The result is a shift by 3. */ speed_distrust = (ao_speed - AO_MS_TO_SPEED(AO_MAX_BARO_SPEED)) >> (4 - 1); if (speed_distrust <= 0) speed_distrust = 0; else if (speed_distrust > height_distrust) height_distrust = speed_distrust; #endif if (height_distrust <= 0) height_distrust = 0; if (height_distrust) { #ifdef AO_FLIGHT_TEST int old_ao_error_h = ao_error_h; #endif if (height_distrust > 0x100) height_distrust = 0x100; ao_error_h = (int16_t) (((int32_t) ao_error_h * (0x100 - height_distrust)) >> 8); #ifdef AO_FLIGHT_TEST if (ao_flight_debug) { printf("over height %g over speed %g distrust: %g height: error %d -> %d\n", (double) (ao_raw_height - AO_MAX_BARO_HEIGHT), (ao_speed - AO_MS_TO_SPEED(AO_MAX_BARO_SPEED)) / 16.0, height_distrust / 256.0, old_ao_error_h, ao_error_h); } #endif } } static void ao_kalman_correct_baro(void) { ao_kalman_err_height(); #ifdef AO_FLIGHT_TEST if (ao_flight_tick - ao_flight_prev_tick > 5) { ao_k_height += (int32_t) AO_BARO_K0_10 * ao_error_h; ao_k_speed += (int32_t) AO_BARO_K1_10 * ao_error_h; ao_k_accel += (int32_t) AO_BARO_K2_10 * ao_error_h; return; } #endif ao_k_height += (int32_t) AO_BARO_K0_100 * ao_error_h; ao_k_speed += (int32_t) AO_BARO_K1_100 * ao_error_h; ao_k_accel += (int32_t) AO_BARO_K2_100 * ao_error_h; } #if HAS_ACCEL static __pdata int16_t ao_error_a; static __pdata int32_t ao_accel_scale; static void ao_kalman_err_accel(void) { int32_t accel; accel = (ao_ground_accel - ao_raw_accel) * ao_accel_scale; /* Can't use ao_accel here as it is the pre-prediction value still */ ao_error_a = (accel - ao_k_accel) >> 16; } static void ao_kalman_correct_both(void) { ao_kalman_err_height(); ao_kalman_err_accel(); #ifdef AO_FLIGHT_TEST if (ao_flight_tick - ao_flight_prev_tick > 5) { if (ao_flight_debug) { printf ("correct speed %g + (%g * %g) + (%g * %g) = %g\n", ao_k_speed / (65536.0 * 16.0), (double) ao_error_h, AO_BOTH_K10_10 / 65536.0, (double) ao_error_a, AO_BOTH_K11_10 / 65536.0, (ao_k_speed + (int32_t) AO_BOTH_K10_10 * ao_error_h + (int32_t) AO_BOTH_K11_10 * ao_error_a) / (65536.0 * 16.0)); } ao_k_height += (int32_t) AO_BOTH_K00_10 * ao_error_h + (int32_t) AO_BOTH_K01_10 * ao_error_a; ao_k_speed += (int32_t) AO_BOTH_K10_10 * ao_error_h + (int32_t) AO_BOTH_K11_10 * ao_error_a; ao_k_accel += (int32_t) AO_BOTH_K20_10 * ao_error_h + (int32_t) AO_BOTH_K21_10 * ao_error_a; return; } if (ao_flight_debug) { printf ("correct speed %g + (%g * %g) + (%g * %g) = %g\n", ao_k_speed / (65536.0 * 16.0), (double) ao_error_h, AO_BOTH_K10_100 / 65536.0, (double) ao_error_a, AO_BOTH_K11_100 / 65536.0, (ao_k_speed + (int32_t) AO_BOTH_K10_100 * ao_error_h + (int32_t) AO_BOTH_K11_100 * ao_error_a) / (65536.0 * 16.0)); } #endif ao_k_height += (int32_t) AO_BOTH_K00_100 * ao_error_h + (int32_t) AO_BOTH_K01_100 * ao_error_a; ao_k_speed += (int32_t) AO_BOTH_K10_100 * ao_error_h + (int32_t) AO_BOTH_K11_100 * ao_error_a; ao_k_accel += (int32_t) AO_BOTH_K20_100 * ao_error_h + (int32_t) AO_BOTH_K21_100 * ao_error_a; } #ifdef FORCE_ACCEL static void ao_kalman_correct_accel(void) { ao_kalman_err_accel(); if (ao_flight_tick - ao_flight_prev_tick > 5) { ao_k_height +=(int32_t) AO_ACCEL_K0_10 * ao_error_a; ao_k_speed += (int32_t) AO_ACCEL_K1_10 * ao_error_a; ao_k_accel += (int32_t) AO_ACCEL_K2_10 * ao_error_a; return; } ao_k_height += (int32_t) AO_ACCEL_K0_100 * ao_error_a; ao_k_speed += (int32_t) AO_ACCEL_K1_100 * ao_error_a; ao_k_accel += (int32_t) AO_ACCEL_K2_100 * ao_error_a; } #endif #endif /* HAS_ACCEL */ __xdata int32_t ao_raw_pres_sum; #ifdef HAS_ACCEL __xdata int32_t ao_raw_accel_sum; #endif /* Landing is detected by getting constant readings from both pressure and accelerometer * for a fairly long time (AO_INTERVAL_TICKS) */ #define AO_INTERVAL_TICKS AO_SEC_TO_TICKS(5) #define abs(a) ((a) < 0 ? -(a) : (a)) void ao_flight(void) { __pdata static uint16_t nsamples = 0; ao_flight_adc = ao_adc_head; ao_raw_pres = 0; #if HAS_ACCEL ao_raw_accel_prev = 0; ao_raw_accel = 0; #endif ao_flight_tick = 0; for (;;) { ao_wakeup(DATA_TO_XDATA(&ao_flight_adc)); ao_sleep(DATA_TO_XDATA(&ao_adc_head)); while (ao_flight_adc != ao_adc_head) { __xdata struct ao_adc *ao_adc; ao_flight_prev_tick = ao_flight_tick; /* Capture a sample */ ao_adc = &ao_adc_ring[ao_flight_adc]; ao_flight_tick = ao_adc->tick; ao_raw_pres = ao_adc->pres; ao_raw_alt = ao_pres_to_altitude(ao_raw_pres); ao_raw_height = ao_raw_alt - ao_ground_height; #if HAS_ACCEL ao_raw_accel = ao_adc->accel; #if HAS_ACCEL_REF /* * Ok, the math here is a bit tricky. * * ao_raw_accel: ADC output for acceleration * ao_accel_ref: ADC output for the 5V reference. * ao_cook_accel: Corrected acceleration value * Vcc: 3.3V supply to the CC1111 * Vac: 5V supply to the accelerometer * accel: input voltage to accelerometer ADC pin * ref: input voltage to 5V reference ADC pin * * * Measured acceleration is ratiometric to Vcc: * * ao_raw_accel accel * ------------ = ----- * 32767 Vcc * * Measured 5v reference is also ratiometric to Vcc: * * ao_accel_ref ref * ------------ = ----- * 32767 Vcc * * * ao_accel_ref = 32767 * (ref / Vcc) * * Acceleration is measured ratiometric to the 5V supply, * so what we want is: * * ao_cook_accel accel * ------------- = ----- * 32767 ref * * * accel Vcc * = ----- * --- * Vcc ref * * ao_raw_accel 32767 * = ------------ * ------------ * 32737 ao_accel_ref * * Multiply through by 32767: * * ao_raw_accel * 32767 * ao_cook_accel = -------------------- * ao_accel_ref * * Now, the tricky part. Getting this to compile efficiently * and keeping all of the values in-range. * * First off, we need to use a shift of 16 instead of * 32767 as SDCC * does the obvious optimizations for byte-granularity shifts: * * ao_cook_accel = (ao_raw_accel << 16) / ao_accel_ref * * Next, lets check our input ranges: * * 0 <= ao_raw_accel <= 0x7fff (singled ended ADC conversion) * 0x7000 <= ao_accel_ref <= 0x7fff (the 5V ref value is close to 0x7fff) * * Plugging in our input ranges, we get an output range of 0 - 0x12490, * which is 17 bits. That won't work. If we take the accel ref and shift * by a bit, we'll change its range: * * 0xe000 <= ao_accel_ref<<1 <= 0xfffe * * ao_cook_accel = (ao_raw_accel << 16) / (ao_accel_ref << 1) * * Now the output range is 0 - 0x9248, which nicely fits in 16 bits. It * is, however, one bit too large for our signed computations. So, we * take the result and shift that by a bit: * * ao_cook_accel = ((ao_raw_accel << 16) / (ao_accel_ref << 1)) >> 1 * * This finally creates an output range of 0 - 0x4924. As the ADC only * provides 11 bits of data, we haven't actually lost any precision, * just dropped a bit of noise off the low end. */ ao_raw_accel = (uint16_t) ((((uint32_t) ao_raw_accel << 16) / (ao_accel_ref[ao_flight_adc] << 1))) >> 1; ao_adc->accel = ao_raw_accel; #endif #endif if (ao_flight_state > ao_flight_idle) { ao_kalman_predict(); #if HAS_ACCEL if (ao_flight_state <= ao_flight_coast) { #ifdef FORCE_ACCEL ao_kalman_correct_accel(); #else ao_kalman_correct_both(); #endif } else #endif ao_kalman_correct_baro(); ao_height = from_fix(ao_k_height); ao_speed = from_fix(ao_k_speed); ao_accel = from_fix(ao_k_accel); if (ao_height > ao_max_height) ao_max_height = ao_height; } ao_flight_adc = ao_adc_ring_next(ao_flight_adc); } switch (ao_flight_state) { case ao_flight_startup: /* startup state: * * Collect 512 samples of acceleration and pressure * data and average them to find the resting values */ if (nsamples < 512) { #if HAS_ACCEL ao_raw_accel_sum += ao_raw_accel; #endif ao_raw_pres_sum += ao_raw_pres; ++nsamples; continue; } ao_config_get(); #if HAS_ACCEL ao_ground_accel = ao_raw_accel_sum >> 9; ao_accel_2g = ao_config.accel_minus_g - ao_config.accel_plus_g; ao_accel_scale = to_fix32(GRAVITY * 2 * 16) / ao_accel_2g; #endif ao_ground_pres = ao_raw_pres_sum >> 9; ao_ground_height = ao_pres_to_altitude(ao_ground_pres); /* Check to see what mode we should go to. * - Invalid mode if accel cal appears to be out * - pad mode if we're upright, * - idle mode otherwise */ #if HAS_ACCEL if (ao_config.accel_plus_g == 0 || ao_config.accel_minus_g == 0 || ao_ground_accel < ao_config.accel_plus_g - ACCEL_NOSE_UP || ao_ground_accel > ao_config.accel_minus_g + ACCEL_NOSE_UP) { /* Detected an accel value outside -1.5g to 1.5g * (or uncalibrated values), so we go into invalid mode */ ao_flight_state = ao_flight_invalid; } else #endif if (!ao_flight_force_idle #if HAS_ACCEL && ao_ground_accel < ao_config.accel_plus_g + ACCEL_NOSE_UP #endif ) { /* Set pad mode - we can fly! */ ao_flight_state = ao_flight_pad; #if HAS_USB /* Disable the USB controller in flight mode * to save power */ ao_usb_disable(); #endif /* Disable packet mode in pad state */ ao_packet_slave_stop(); /* Turn on telemetry system */ ao_rdf_set(1); ao_telemetry_set_interval(AO_TELEMETRY_INTERVAL_PAD); /* signal successful initialization by turning off the LED */ ao_led_off(AO_LED_RED); } else { /* Set idle mode */ ao_flight_state = ao_flight_idle; /* signal successful initialization by turning off the LED */ ao_led_off(AO_LED_RED); } /* wakeup threads due to state change */ ao_wakeup(DATA_TO_XDATA(&ao_flight_state)); break; case ao_flight_pad: /* pad to boost: * * barometer: > 20m vertical motion * OR * accelerometer: > 2g AND velocity > 5m/s * * The accelerometer should always detect motion before * the barometer, but we use both to make sure this * transition is detected. If the device * doesn't have an accelerometer, then ignore the * speed and acceleration as they are quite noisy * on the pad. */ if (ao_height > AO_M_TO_HEIGHT(20) #if HAS_ACCEL || (ao_accel > AO_MSS_TO_ACCEL(20) && ao_speed > AO_MS_TO_SPEED(5)) #endif ) { ao_flight_state = ao_flight_boost; ao_launch_tick = ao_flight_tick; /* start logging data */ ao_log_start(); /* Increase telemetry rate */ ao_telemetry_set_interval(AO_TELEMETRY_INTERVAL_FLIGHT); /* disable RDF beacon */ ao_rdf_set(0); #if HAS_GPS /* Record current GPS position by waking up GPS log tasks */ ao_wakeup(&ao_gps_data); ao_wakeup(&ao_gps_tracking_data); #endif ao_wakeup(DATA_TO_XDATA(&ao_flight_state)); break; } break; case ao_flight_boost: /* boost to fast: * * accelerometer: start to fall at > 1/4 G * OR * time: boost for more than 15 seconds * * Detects motor burn out by the switch from acceleration to * deceleration, or by waiting until the maximum burn duration * (15 seconds) has past. */ if ((ao_accel < AO_MSS_TO_ACCEL(-2.5) && ao_height > AO_M_TO_HEIGHT(100)) || (int16_t) (ao_flight_tick - ao_launch_tick) > BOOST_TICKS_MAX) { #if HAS_ACCEL ao_flight_state = ao_flight_fast; #else ao_flight_state = ao_flight_coast; #endif ao_wakeup(DATA_TO_XDATA(&ao_flight_state)); break; } break; #if HAS_ACCEL case ao_flight_fast: /* * This is essentially the same as coast, * but the barometer is being ignored as * it may be unreliable. */ if (ao_speed < AO_MS_TO_SPEED(AO_MAX_BARO_SPEED)) { ao_flight_state = ao_flight_coast; ao_wakeup(DATA_TO_XDATA(&ao_flight_state)); break; } break; #endif case ao_flight_coast: /* apogee detect: coast to drogue deploy: * * speed: < 0 * * Also make sure the model altitude is tracking * the measured altitude reasonably closely; otherwise * we're probably transsonic. */ if (ao_speed < 0 #if !HAS_ACCEL && (ao_raw_alt >= AO_MAX_BARO_HEIGHT || ao_error_h_sq_avg < 100) #endif ) { /* ignite the drogue charge */ ao_ignite(ao_igniter_drogue); /* slow down the telemetry system */ ao_telemetry_set_interval(AO_TELEMETRY_INTERVAL_RECOVER); /* * Start recording min/max height * to figure out when the rocket has landed */ /* initialize interval values */ ao_interval_end = ao_flight_tick + AO_INTERVAL_TICKS; ao_interval_min_height = ao_interval_max_height = ao_height; /* and enter drogue state */ ao_flight_state = ao_flight_drogue; ao_wakeup(DATA_TO_XDATA(&ao_flight_state)); } break; case ao_flight_drogue: /* drogue to main deploy: * * barometer: reach main deploy altitude * * Would like to use the accelerometer for this test, but * the orientation of the flight computer is unknown after * drogue deploy, so we ignore it. Could also detect * high descent rate using the pressure sensor to * recognize drogue deploy failure and eject the main * at that point. Perhaps also use the drogue sense lines * to notice continutity? */ if (ao_height <= ao_config.main_deploy) { ao_ignite(ao_igniter_main); ao_flight_state = ao_flight_main; ao_wakeup(DATA_TO_XDATA(&ao_flight_state)); } /* fall through... */ case ao_flight_main: /* drogue/main to land: * * barometer: altitude stable and within 1000m of the launch altitude */ if (ao_height < ao_interval_min_height) ao_interval_min_height = ao_height; if (ao_height > ao_interval_max_height) ao_interval_max_height = ao_height; if ((int16_t) (ao_flight_tick - ao_interval_end) >= 0) { if (ao_height < AO_M_TO_HEIGHT(1000) && ao_interval_max_height - ao_interval_min_height < AO_M_TO_HEIGHT(5)) { ao_flight_state = ao_flight_landed; /* turn off the ADC capture */ ao_timer_set_adc_interval(0); /* Enable RDF beacon */ ao_rdf_set(1); ao_wakeup(DATA_TO_XDATA(&ao_flight_state)); } ao_interval_min_height = ao_interval_max_height = ao_height; ao_interval_end = ao_flight_tick + AO_INTERVAL_TICKS; } break; case ao_flight_landed: break; } } } static __xdata struct ao_task flight_task; void ao_flight_init(void) { ao_flight_state = ao_flight_startup; ao_add_task(&flight_task, ao_flight, "flight"); }