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GPS.cpp
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#include "Arduino.h"
#include "config.h"
#include "def.h"
#include "types.h"
#include "GPS.h"
#include "Serial.h"
#include "Sensors.h"
#include "BalancingWii.h"
#if GPS
bool GPS_newFrame(char c);
#if defined(NMEA)
bool GPS_NMEA_newFrame(char c);
#endif
#if defined(UBLOX)
bool GPS_UBLOX_newFrame(uint8_t data);
bool UBLOX_parse_gps(void);
#endif
#if defined(MTK_BINARY16) || defined(MTK_BINARY19)
bool GPS_MTK_newFrame(uint8_t data);
#endif
void GPS_distance_cm_bearing(int32_t* lat1, int32_t* lon1, int32_t* lat2, int32_t* lon2,uint32_t* dist, int32_t* bearing);
static void GPS_calc_velocity(void);
static void GPS_calc_location_error( int32_t* target_lat, int32_t* target_lng, int32_t* gps_lat, int32_t* gps_lng );
static void GPS_calc_poshold(void);
static uint16_t GPS_calc_desired_speed(uint16_t max_speed, bool _slow);
static void GPS_calc_nav_rate(uint16_t max_speed);
int32_t wrap_18000(int32_t ang);
static bool check_missed_wp(void);
void GPS_calc_longitude_scaling(int32_t lat);
static void GPS_update_crosstrack(void);
int32_t wrap_36000(int32_t ang);
#if defined(INIT_MTK_GPS)
#define MTK_SET_BINARY PSTR("$PGCMD,16,0,0,0,0,0*6A\r\n")
#define MTK_SET_NMEA PSTR("$PGCMD,16,1,1,1,1,1*6B\r\n")
#define MTK_SET_NMEA_SENTENCES PSTR("$PMTK314,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0*28\r\n")
#define MTK_OUTPUT_4HZ PSTR("$PMTK220,250*29\r\n")
#define MTK_OUTPUT_5HZ PSTR("$PMTK220,200*2C\r\n")
#define MTK_OUTPUT_10HZ PSTR("$PMTK220,100*2F\r\n")
#define MTK_NAVTHRES_OFF PSTR("$PMTK397,0*23\r\n") // Set Nav Threshold (the minimum speed the GPS must be moving to update the position) to 0 m/s
#define SBAS_ON PSTR("$PMTK313,1*2E\r\n")
#define WAAS_ON PSTR("$PMTK301,2*2E\r\n")
#define SBAS_TEST_MODE PSTR("$PMTK319,0*25\r\n") //Enable test use of sbas satelite in test mode (usually PRN124 is in test mode)
#endif
#if defined(GPS_SERIAL) || defined(GPS_FROM_OSD)
#if defined(GPS_LEAD_FILTER)
// Set up gps lag
#if defined(UBLOX)
#define GPS_LAG 0.5f //UBLOX GPS has a smaller lag than MTK and other
#else
#define GPS_LAG 1.0f //We assumes that MTK GPS has a 1 sec lag
#endif
static int32_t GPS_coord_lead[2]; // Lead filtered gps coordinates
class LeadFilter {
public:
LeadFilter() :
_last_velocity(0) {
}
// setup min and max radio values in CLI
int32_t get_position(int32_t pos, int16_t vel, float lag_in_seconds = 1.0);
void clear() { _last_velocity = 0; }
private:
int16_t _last_velocity;
};
int32_t LeadFilter::get_position(int32_t pos, int16_t vel, float lag_in_seconds)
{
int16_t accel_contribution = (vel - _last_velocity) * lag_in_seconds * lag_in_seconds;
int16_t vel_contribution = vel * lag_in_seconds;
// store velocity for next iteration
_last_velocity = vel;
return pos + vel_contribution + accel_contribution;
}
LeadFilter xLeadFilter; // Long GPS lag filter
LeadFilter yLeadFilter; // Lat GPS lag filter
#endif
typedef struct PID_PARAM_ {
float kP;
float kI;
float kD;
float Imax;
} PID_PARAM;
PID_PARAM posholdPID_PARAM;
PID_PARAM poshold_ratePID_PARAM;
PID_PARAM navPID_PARAM;
typedef struct PID_ {
float integrator; // integrator value
int32_t last_input; // last input for derivative
float lastderivative; // last derivative for low-pass filter
float output;
float derivative;
} PID;
PID posholdPID[2];
PID poshold_ratePID[2];
PID navPID[2];
int32_t get_P(int32_t error, struct PID_PARAM_* pid) {
return (float)error * pid->kP;
}
int32_t get_I(int32_t error, float* dt, struct PID_* pid, struct PID_PARAM_* pid_param) {
pid->integrator += ((float)error * pid_param->kI) * *dt;
pid->integrator = constrain(pid->integrator,-pid_param->Imax,pid_param->Imax);
return pid->integrator;
}
int32_t get_D(int32_t input, float* dt, struct PID_* pid, struct PID_PARAM_* pid_param) { // dt in milliseconds
pid->derivative = (input - pid->last_input) / *dt;
/// Low pass filter cut frequency for derivative calculation.
float filter = 7.9577e-3; // Set to "1 / ( 2 * PI * f_cut )";
// Examples for _filter:
// f_cut = 10 Hz -> _filter = 15.9155e-3
// f_cut = 15 Hz -> _filter = 10.6103e-3
// f_cut = 20 Hz -> _filter = 7.9577e-3
// f_cut = 25 Hz -> _filter = 6.3662e-3
// f_cut = 30 Hz -> _filter = 5.3052e-3
// discrete low pass filter, cuts out the
// high frequency noise that can drive the controller crazy
pid->derivative = pid->lastderivative + (*dt / ( filter + *dt)) * (pid->derivative - pid->lastderivative);
// update state
pid->last_input = input;
pid->lastderivative = pid->derivative;
// add in derivative component
return pid_param->kD * pid->derivative;
}
void reset_PID(struct PID_* pid) {
pid->integrator = 0;
pid->last_input = 0;
pid->lastderivative = 0;
}
#define _X 1
#define _Y 0
#define RADX100 0.000174532925
#define CROSSTRACK_GAIN 1
#define NAV_SPEED_MIN 100 // cm/sec
#define NAV_SPEED_MAX 300 // cm/sec
#define NAV_SLOW_NAV true
#define NAV_BANK_MAX 3000 //30deg max banking when navigating (just for security and testing)
static float dTnav; // Delta Time in milliseconds for navigation computations, updated with every good GPS read
static uint16_t GPS_wp_radius = GPS_WP_RADIUS;
static int16_t actual_speed[2] = {0,0};
static float GPS_scaleLonDown; // this is used to offset the shrinking longitude as we go towards the poles
// The difference between the desired rate of travel and the actual rate of travel
// updated after GPS read - 5-10hz
static int16_t rate_error[2];
static int32_t error[2];
//Currently used WP
static int32_t GPS_WP[2];
////////////////////////////////////////////////////////////////////////////////
// Location & Navigation
////////////////////////////////////////////////////////////////////////////////
// This is the angle from the copter to the "next_WP" location in degrees * 100
static int32_t target_bearing;
////////////////////////////////////////////////////////////////////////////////
// Crosstrack
////////////////////////////////////////////////////////////////////////////////
// deg * 100, The original angle to the next_WP when the next_WP was set
// Also used to check when we pass a WP
static int32_t original_target_bearing;
// The amount of angle correction applied to target_bearing to bring the copter back on its optimum path
static int16_t crosstrack_error;
////////////////////////////////////////////////////////////////////////////////
// The location of the copter in relation to home, updated every GPS read (1deg - 100)
// static int32_t home_to_copter_bearing; /* unused */
// distance between plane and home in cm
// static int32_t home_distance; /* unused */
// distance between plane and next_WP in cm
static uint32_t wp_distance;
// used for slow speed wind up when start navigation;
static uint16_t waypoint_speed_gov;
////////////////////////////////////////////////////////////////////////////////////
// moving average filter variables
//
#define GPS_FILTER_VECTOR_LENGTH 5
static uint8_t GPS_filter_index = 0;
static int32_t GPS_filter[2][GPS_FILTER_VECTOR_LENGTH];
static int32_t GPS_filter_sum[2];
static int32_t GPS_read[2];
static int32_t GPS_filtered[2];
static int32_t GPS_degree[2]; //the lat lon degree without any decimals (lat/10 000 000)
static uint16_t fraction3[2];
#endif
// This is the angle from the copter to the "next_WP" location
// with the addition of Crosstrack error in degrees * 100
static int32_t nav_bearing;
// saves the bearing at takeof (1deg = 1) used to rotate to takeoff direction when arrives at home
static int16_t nav_takeoff_bearing;
#if defined(I2C_GPS)
/////////////////////////////////////////////////////////////////////////////////////////
// I2C GPS helper functions
//
// Send a command to the I2C GPS module, first parameter command, second parameter wypoint number
void GPS_I2C_command(uint8_t command, uint8_t wp) {
uint8_t _cmd;
_cmd = (wp << 4) + command;
i2c_rep_start(I2C_GPS_ADDRESS<<1);
i2c_write(I2C_GPS_COMMAND);
i2c_write(_cmd);
}
#endif
#if defined(GPS_SERIAL)
#if defined(INIT_MTK_GPS) || defined(UBLOX)
uint32_t init_speed[5] = {9600,19200,38400,57600,115200};
void SerialGpsPrint(const char PROGMEM * str) {
char b;
while(str && (b = pgm_read_byte(str++))) {
SerialWrite(GPS_SERIAL, b);
#if defined(UBLOX)
delay(5);
#endif
}
}
#endif
#if defined(UBLOX)
prog_char UBLOX_INIT[] PROGMEM = { // PROGMEM array must be outside any function !!!
0xB5,0x62,0x06,0x01,0x03,0x00,0xF0,0x05,0x00,0xFF,0x19, //disable all default NMEA messages
0xB5,0x62,0x06,0x01,0x03,0x00,0xF0,0x03,0x00,0xFD,0x15,
0xB5,0x62,0x06,0x01,0x03,0x00,0xF0,0x01,0x00,0xFB,0x11,
0xB5,0x62,0x06,0x01,0x03,0x00,0xF0,0x00,0x00,0xFA,0x0F,
0xB5,0x62,0x06,0x01,0x03,0x00,0xF0,0x02,0x00,0xFC,0x13,
0xB5,0x62,0x06,0x01,0x03,0x00,0xF0,0x04,0x00,0xFE,0x17,
0xB5,0x62,0x06,0x01,0x03,0x00,0x01,0x02,0x01,0x0E,0x47, //set POSLLH MSG rate
0xB5,0x62,0x06,0x01,0x03,0x00,0x01,0x03,0x01,0x0F,0x49, //set STATUS MSG rate
0xB5,0x62,0x06,0x01,0x03,0x00,0x01,0x06,0x01,0x12,0x4F, //set SOL MSG rate
0xB5,0x62,0x06,0x01,0x03,0x00,0x01,0x12,0x01,0x1E,0x67, //set VELNED MSG rate
0xB5,0x62,0x06,0x16,0x08,0x00,0x03,0x07,0x03,0x00,0x51,0x08,0x00,0x00,0x8A,0x41, //set WAAS to EGNOS
0xB5, 0x62, 0x06, 0x08, 0x06, 0x00, 0xC8, 0x00, 0x01, 0x00, 0x01, 0x00, 0xDE, 0x6A //set rate to 5Hz
};
#endif
void GPS_SerialInit(void) {
SerialOpen(GPS_SERIAL,GPS_BAUD);
delay(1000);
#if defined(UBLOX)
for(uint8_t i=0;i<5;i++){
SerialOpen(GPS_SERIAL,init_speed[i]); // switch UART speed for sending SET BAUDRATE command (NMEA mode)
#if (GPS_BAUD==19200)
SerialGpsPrint(PSTR("$PUBX,41,1,0003,0001,19200,0*23\r\n")); // 19200 baud - minimal speed for 5Hz update rate
#endif
#if (GPS_BAUD==38400)
SerialGpsPrint(PSTR("$PUBX,41,1,0003,0001,38400,0*26\r\n")); // 38400 baud
#endif
#if (GPS_BAUD==57600)
SerialGpsPrint(PSTR("$PUBX,41,1,0003,0001,57600,0*2D\r\n")); // 57600 baud
#endif
#if (GPS_BAUD==115200)
SerialGpsPrint(PSTR("$PUBX,41,1,0003,0001,115200,0*1E\r\n")); // 115200 baud
#endif
while(!SerialTXfree(GPS_SERIAL)) delay(10);
}
delay(200);
SerialOpen(GPS_SERIAL,GPS_BAUD);
for(uint8_t i=0; i<sizeof(UBLOX_INIT); i++) { // send configuration data in UBX protocol
SerialWrite(GPS_SERIAL, pgm_read_byte(UBLOX_INIT+i));
delay(5); //simulating a 38400baud pace (or less), otherwise commands are not accepted by the device.
}
#elif defined(INIT_MTK_GPS) // MTK GPS setup
for(uint8_t i=0;i<5;i++){
SerialOpen(GPS_SERIAL,init_speed[i]); // switch UART speed for sending SET BAUDRATE command
#if (GPS_BAUD==19200)
SerialGpsPrint(PSTR("$PMTK251,19200*22\r\n")); // 19200 baud - minimal speed for 5Hz update rate
#endif
#if (GPS_BAUD==38400)
SerialGpsPrint(PSTR("$PMTK251,38400*27\r\n")); // 38400 baud
#endif
#if (GPS_BAUD==57600)
SerialGpsPrint(PSTR("$PMTK251,57600*2C\r\n")); // 57600 baud
#endif
#if (GPS_BAUD==115200)
SerialGpsPrint(PSTR("$PMTK251,115200*1F\r\n")); // 115200 baud
#endif
while(!SerialTXfree(GPS_SERIAL)) delay(80);
}
// at this point we have GPS working at selected (via #define GPS_BAUD) baudrate
// So now we have to set the desired mode and update rate (which depends on the NMEA or MTK_BINARYxx settings)
SerialOpen(GPS_SERIAL,GPS_BAUD);
SerialGpsPrint(MTK_NAVTHRES_OFF);
while(!SerialTXfree(GPS_SERIAL)) delay(80);
SerialGpsPrint(SBAS_ON);
while(!SerialTXfree(GPS_SERIAL)) delay(80);
SerialGpsPrint(WAAS_ON);
while(!SerialTXfree(GPS_SERIAL)) delay(80);
SerialGpsPrint(SBAS_TEST_MODE);
while(!SerialTXfree(GPS_SERIAL)) delay(80);
SerialGpsPrint(MTK_OUTPUT_5HZ); // 5 Hz update rate
#if defined(NMEA)
SerialGpsPrint(MTK_SET_NMEA_SENTENCES); // only GGA and RMC sentence
#endif
#if defined(MTK_BINARY19) || defined(MTK_BINARY16)
SerialGpsPrint(MTK_SET_BINARY);
#endif
#endif //elif init_mtk_gps
}
#endif //gps_serial
void GPS_NewData(void) {
uint8_t axis;
#if defined(I2C_GPS)
static uint8_t GPS_pids_initialized;
static uint8_t _i2c_gps_status;
//Do not use i2c_writereg, since writing a register does not work if an i2c_stop command is issued at the end
//Still investigating, however with separated i2c_repstart and i2c_write commands works... and did not caused i2c errors on a long term test.
GPS_numSat = (_i2c_gps_status & 0xf0) >> 4;
_i2c_gps_status = i2c_readReg(I2C_GPS_ADDRESS,I2C_GPS_STATUS_00); //Get status register
uint8_t *varptr;
#if defined(I2C_GPS_SONAR)
i2c_rep_start(I2C_GPS_ADDRESS<<1);
i2c_write(I2C_GPS_SONAR_ALT);
i2c_rep_start((I2C_GPS_ADDRESS<<1)|1);
varptr = (uint8_t *)&sonarAlt; // altitude (in cm? maybe)
*varptr++ = i2c_readAck();
*varptr = i2c_readNak();
#endif
if (_i2c_gps_status & I2C_GPS_STATUS_3DFIX) { //Check is we have a good 3d fix (numsats>5)
f.GPS_FIX = 1;
#if !defined(DONT_RESET_HOME_AT_ARM)
if (!f.ARMED) {f.GPS_FIX_HOME = 0;} //Clear home position if disarmed
#endif
if (!f.GPS_FIX_HOME && f.ARMED) { //if home is not set set home position to WP#0 and activate it
GPS_reset_home_position();
}
if (_i2c_gps_status & I2C_GPS_STATUS_NEW_DATA) { //Check about new data
if (GPS_update) { GPS_update = 0;} else { GPS_update = 1;} //Fancy flash on GUI :D
if (!GPS_pids_initialized) {
GPS_set_pids();
GPS_pids_initialized = 1;
}
//Read GPS data for distance, heading and gps position
i2c_rep_start(I2C_GPS_ADDRESS<<1);
i2c_write(I2C_GPS_NAV_BEARING); //Start read from here 2x2 bytes distance and direction
i2c_rep_start((I2C_GPS_ADDRESS<<1)|1);
varptr = (uint8_t *)&nav_bearing;
*varptr++ = i2c_readAck();
*varptr = i2c_readAck();
varptr = (uint8_t *)&GPS_directionToHome;
*varptr++ = i2c_readAck();
*varptr = i2c_readAck();
GPS_directionToHome = GPS_directionToHome / 100; // 1deg =1000 in the reg, downsize
GPS_directionToHome += 180; // fix (see http://www.multiwii.com/forum/viewtopic.php?f=8&t=2892)
if (GPS_directionToHome>180) GPS_directionToHome -= 360;
varptr = (uint8_t *)&GPS_distanceToHome;
*varptr++ = i2c_readAck();
*varptr = i2c_readNak();
GPS_distanceToHome = GPS_distanceToHome / 100; //register is in CM, we need in meter. max= 655 meters with this way
i2c_rep_start(I2C_GPS_ADDRESS<<1);
i2c_write(I2C_GPS_LOCATION); //Start read from here 2x2 bytes distance and direction
i2c_rep_start((I2C_GPS_ADDRESS<<1)|1);
varptr = (uint8_t *)&GPS_coord[LAT]; // for latitude displaying
*varptr++ = i2c_readAck();
*varptr++ = i2c_readAck();
*varptr++ = i2c_readAck();
*varptr = i2c_readAck();
varptr = (uint8_t *)&GPS_coord[LON]; // for longitude displaying
*varptr++ = i2c_readAck();
*varptr++ = i2c_readAck();
*varptr++ = i2c_readAck();
*varptr = i2c_readAck();
varptr = (uint8_t *)&nav[LAT];
*varptr++ = i2c_readAck();
*varptr++ = i2c_readAck();
varptr = (uint8_t *)&nav[LON];
*varptr++ = i2c_readAck();
*varptr++ = i2c_readNak();
i2c_rep_start(I2C_GPS_ADDRESS<<1);
i2c_write(I2C_GPS_GROUND_SPEED);
i2c_rep_start((I2C_GPS_ADDRESS<<1)|1);
varptr = (uint8_t *)&GPS_speed; // speed in cm/s for OSD
*varptr++ = i2c_readAck();
*varptr = i2c_readAck();
varptr = (uint8_t *)&GPS_altitude; // altitude in meters for OSD
*varptr++ = i2c_readAck();
*varptr = i2c_readAck();
//GPS_ground_course
varptr = (uint8_t *)&GPS_ground_course;
*varptr++ = i2c_readAck();
*varptr = i2c_readNak();
if (!f.GPS_FIX_HOME) { //If we don't have home set, do not display anything
GPS_distanceToHome = 0;
GPS_directionToHome = 0;
}
//Adjust heading when navigating
if (f.GPS_HOME_MODE) {
if ( !(_i2c_gps_status & I2C_GPS_STATUS_WP_REACHED) ) {
//Tail control
if (NAV_CONTROLS_HEADING) {
if (NAV_TAIL_FIRST) {
magHold = nav_bearing/100-180;
if (magHold > 180) magHold -= 360;
if (magHold < -180) magHold += 360;
} else {
magHold = nav_bearing/100;
}
}
} else { //Home position reached
if (NAV_SET_TAKEOFF_HEADING) { magHold = nav_takeoff_bearing; }
}
}
}
} else { //We don't have a fix zero out distance and bearing (for safety reasons)
GPS_distanceToHome = 0;
GPS_directionToHome = 0;
GPS_numSat = 0;
f.GPS_FIX = 0;
}
#endif
#if defined(GPS_SERIAL) || defined(GPS_FROM_OSD)
#if defined(GPS_SERIAL)
uint8_t c = SerialAvailable(GPS_SERIAL);
while (c--) {
//while (SerialAvailable(GPS_SERIAL)) {
if (GPS_newFrame(SerialRead(GPS_SERIAL))) {
#elif defined(GPS_FROM_OSD)
{
if(GPS_update & 2) { // Once second bit of GPS_update is set, indicate new GPS datas is readed from OSD - all in right format.
GPS_update &= 1; // We have: GPS_fix(0-2), GPS_numSat(0-15), GPS_coord[LAT & LON](signed, in 1/10 000 000 degres), GPS_altitude(signed, in meters) and GPS_speed(in cm/s)
#endif
if (GPS_update == 1) GPS_update = 0; else GPS_update = 1;
if (f.GPS_FIX && GPS_numSat >= 5) {
#if !defined(DONT_RESET_HOME_AT_ARM)
if (!f.ARMED) {f.GPS_FIX_HOME = 0;}
#endif
if (!f.GPS_FIX_HOME && f.ARMED) {
GPS_reset_home_position();
}
//Apply moving average filter to GPS data
#if defined(GPS_FILTERING)
GPS_filter_index = (GPS_filter_index+1) % GPS_FILTER_VECTOR_LENGTH;
for (axis = 0; axis< 2; axis++) {
GPS_read[axis] = GPS_coord[axis]; //latest unfiltered data is in GPS_latitude and GPS_longitude
GPS_degree[axis] = GPS_read[axis] / 10000000; // get the degree to assure the sum fits to the int32_t
// How close we are to a degree line ? its the first three digits from the fractions of degree
// later we use it to Check if we are close to a degree line, if yes, disable averaging,
fraction3[axis] = (GPS_read[axis]- GPS_degree[axis]*10000000) / 10000;
GPS_filter_sum[axis] -= GPS_filter[axis][GPS_filter_index];
GPS_filter[axis][GPS_filter_index] = GPS_read[axis] - (GPS_degree[axis]*10000000);
GPS_filter_sum[axis] += GPS_filter[axis][GPS_filter_index];
GPS_filtered[axis] = GPS_filter_sum[axis] / GPS_FILTER_VECTOR_LENGTH + (GPS_degree[axis]*10000000);
if ( nav_mode == NAV_MODE_POSHOLD) { //we use gps averaging only in poshold mode...
if ( fraction3[axis]>1 && fraction3[axis]<999 ) GPS_coord[axis] = GPS_filtered[axis];
}
}
#endif
//dTnav calculation
//Time for calculating x,y speed and navigation pids
static uint32_t nav_loopTimer;
dTnav = (float)(millis() - nav_loopTimer)/ 1000.0;
nav_loopTimer = millis();
// prevent runup from bad GPS
dTnav = min(dTnav, 1.0);
//calculate distance and bearings for gui and other stuff continously - From home to copter
uint32_t dist;
int32_t dir;
GPS_distance_cm_bearing(&GPS_coord[LAT],&GPS_coord[LON],&GPS_home[LAT],&GPS_home[LON],&dist,&dir);
GPS_distanceToHome = dist/100;
GPS_directionToHome = dir/100;
if (!f.GPS_FIX_HOME) { //If we don't have home set, do not display anything
GPS_distanceToHome = 0;
GPS_directionToHome = 0;
}
//calculate the current velocity based on gps coordinates continously to get a valid speed at the moment when we start navigating
GPS_calc_velocity();
if (f.GPS_HOLD_MODE || f.GPS_HOME_MODE){ //ok we are navigating
//do gps nav calculations here, these are common for nav and poshold
#if defined(GPS_LEAD_FILTER)
GPS_distance_cm_bearing(&GPS_coord_lead[LAT],&GPS_coord_lead[LON],&GPS_WP[LAT],&GPS_WP[LON],&wp_distance,&target_bearing);
GPS_calc_location_error(&GPS_WP[LAT],&GPS_WP[LON],&GPS_coord_lead[LAT],&GPS_coord_lead[LON]);
#else
GPS_distance_cm_bearing(&GPS_coord[LAT],&GPS_coord[LON],&GPS_WP[LAT],&GPS_WP[LON],&wp_distance,&target_bearing);
GPS_calc_location_error(&GPS_WP[LAT],&GPS_WP[LON],&GPS_coord[LAT],&GPS_coord[LON]);
#endif
switch (nav_mode) {
case NAV_MODE_POSHOLD:
//Desired output is in nav_lat and nav_lon where 1deg inclination is 100
GPS_calc_poshold();
break;
case NAV_MODE_WP:
int16_t speed = GPS_calc_desired_speed(NAV_SPEED_MAX, NAV_SLOW_NAV); //slow navigation
// use error as the desired rate towards the target
//Desired output is in nav_lat and nav_lon where 1deg inclination is 100
GPS_calc_nav_rate(speed);
//Tail control
if (NAV_CONTROLS_HEADING) {
if (NAV_TAIL_FIRST) {
magHold = wrap_18000(nav_bearing-18000)/100;
} else {
magHold = nav_bearing/100;
}
}
// Are we there yet ?(within 2 meters of the destination)
if ((wp_distance <= GPS_wp_radius) || check_missed_wp()){ //if yes switch to poshold mode
nav_mode = NAV_MODE_POSHOLD;
if (NAV_SET_TAKEOFF_HEADING) { magHold = nav_takeoff_bearing; }
}
break;
}
} //end of gps calcs
}
}
}
#endif
}
void GPS_reset_home_position(void) {
if (f.GPS_FIX && GPS_numSat >= 5) {
#if defined(I2C_GPS)
//set current position as home
GPS_I2C_command(I2C_GPS_COMMAND_SET_WP,0); //WP0 is the home position
#else
GPS_home[LAT] = GPS_coord[LAT];
GPS_home[LON] = GPS_coord[LON];
GPS_calc_longitude_scaling(GPS_coord[LAT]); //need an initial value for distance and bearing calc
#endif
nav_takeoff_bearing = att.heading; //save takeoff heading
//Set ground altitude
f.GPS_FIX_HOME = 1;
}
}
//reset navigation (stop the navigation processor, and clear nav)
void GPS_reset_nav(void) {
uint8_t i;
for(i=0;i<2;i++) {
nav_rated[i] = 0;
nav[i] = 0;
#if defined(I2C_GPS)
GPS_I2C_command(I2C_GPS_COMMAND_STOP_NAV,0);
#else
reset_PID(&posholdPID[i]);
reset_PID(&poshold_ratePID[i]);
reset_PID(&navPID[i]);
nav_mode = NAV_MODE_NONE;
#endif
}
}
//Get the relevant P I D values and set the PID controllers
void GPS_set_pids(void) {
#if defined(GPS_SERIAL) || defined(GPS_FROM_OSD)
posholdPID_PARAM.kP = (float)conf.pid[PIDPOS].P8/100.0;
posholdPID_PARAM.kI = (float)conf.pid[PIDPOS].I8/100.0;
posholdPID_PARAM.Imax = POSHOLD_RATE_IMAX * 100;
poshold_ratePID_PARAM.kP = (float)conf.pid[PIDPOSR].P8/10.0;
poshold_ratePID_PARAM.kI = (float)conf.pid[PIDPOSR].I8/100.0;
poshold_ratePID_PARAM.kD = (float)conf.pid[PIDPOSR].D8/1000.0;
poshold_ratePID_PARAM.Imax = POSHOLD_RATE_IMAX * 100;
navPID_PARAM.kP = (float)conf.pid[PIDNAVR].P8/10.0;
navPID_PARAM.kI = (float)conf.pid[PIDNAVR].I8/100.0;
navPID_PARAM.kD = (float)conf.pid[PIDNAVR].D8/1000.0;
navPID_PARAM.Imax = POSHOLD_RATE_IMAX * 100;
#endif
#if defined(I2C_GPS)
i2c_rep_start(I2C_GPS_ADDRESS<<1);
i2c_write(I2C_GPS_HOLD_P);
i2c_write(conf.pid[PIDPOS].P8);
i2c_write(conf.pid[PIDPOS].I8);
i2c_rep_start(I2C_GPS_ADDRESS<<1);
i2c_write(I2C_GPS_HOLD_RATE_P);
i2c_write(conf.pid[PIDPOSR].P8);
i2c_write(conf.pid[PIDPOSR].I8);
i2c_write(conf.pid[PIDPOSR].D8);
i2c_rep_start(I2C_GPS_ADDRESS<<1);
i2c_write(I2C_GPS_NAV_P);
i2c_write(conf.pid[PIDNAVR].P8);
i2c_write(conf.pid[PIDNAVR].I8);
i2c_write(conf.pid[PIDNAVR].D8);
GPS_I2C_command(I2C_GPS_COMMAND_UPDATE_PIDS,0);
uint8_t nav_flags = 0;
#if defined(GPS_FILTERING)
nav_flags += I2C_NAV_FLAG_GPS_FILTER;
#endif
#if defined(GPS_LOW_SPEED_D_FILTER)
nav_flags += I2C_NAV_FLAG_LOW_SPEED_D_FILTER;
#endif
i2c_rep_start(I2C_GPS_ADDRESS<<1);
i2c_write(I2C_GPS_NAV_FLAGS);
i2c_write(nav_flags);
i2c_rep_start(I2C_GPS_ADDRESS<<1);
i2c_write(I2C_GPS_WP_RADIUS);
i2c_write(GPS_WP_RADIUS & 0x00FF); // lower eight bit
i2c_write(GPS_WP_RADIUS >> 8); // upper eight bit
#endif
}
//It was mobed here since even i2cgps code needs it
int32_t wrap_18000(int32_t ang) {
if (ang > 18000) ang -= 36000;
if (ang < -18000) ang += 36000;
return ang;
}
//OK here is the onboard GPS code
#if defined(GPS_SERIAL) || defined(GPS_FROM_OSD)
////////////////////////////////////////////////////////////////////////////////////
//PID based GPS navigation functions
//Author : EOSBandi
//Based on code and ideas from the Arducopter team: Jason Short,Randy Mackay, Pat Hickey, Jose Julio, Jani Hirvinen
//Andrew Tridgell, Justin Beech, Adam Rivera, Jean-Louis Naudin, Roberto Navoni
////////////////////////////////////////////////////////////////////////////////////
// this is used to offset the shrinking longitude as we go towards the poles
// It's ok to calculate this once per waypoint setting, since it changes a little within the reach of a multicopter
//
void GPS_calc_longitude_scaling(int32_t lat) {
float rads = (abs((float)lat) / 10000000.0) * 0.0174532925;
GPS_scaleLonDown = cos(rads);
}
////////////////////////////////////////////////////////////////////////////////////
// Sets the waypoint to navigate, reset neccessary variables and calculate initial values
//
void GPS_set_next_wp(int32_t* lat, int32_t* lon) {
GPS_WP[LAT] = *lat;
GPS_WP[LON] = *lon;
GPS_calc_longitude_scaling(*lat);
GPS_distance_cm_bearing(&GPS_coord[LAT],&GPS_coord[LON],&GPS_WP[LAT],&GPS_WP[LON],&wp_distance,&target_bearing);
nav_bearing = target_bearing;
GPS_calc_location_error(&GPS_WP[LAT],&GPS_WP[LON],&GPS_coord[LAT],&GPS_coord[LON]);
original_target_bearing = target_bearing;
waypoint_speed_gov = NAV_SPEED_MIN;
}
////////////////////////////////////////////////////////////////////////////////////
// Check if we missed the destination somehow
//
static bool check_missed_wp(void) {
int32_t temp;
temp = target_bearing - original_target_bearing;
temp = wrap_18000(temp);
return (abs(temp) > 10000); // we passed the waypoint by 100 degrees
}
////////////////////////////////////////////////////////////////////////////////////
// Get distance between two points in cm
// Get bearing from pos1 to pos2, returns an 1deg = 100 precision
void GPS_distance_cm_bearing(int32_t* lat1, int32_t* lon1, int32_t* lat2, int32_t* lon2,uint32_t* dist, int32_t* bearing) {
float dLat = *lat2 - *lat1; // difference of latitude in 1/10 000 000 degrees
float dLon = (float)(*lon2 - *lon1) * GPS_scaleLonDown;
*dist = sqrt(sq(dLat) + sq(dLon)) * 1.113195;
*bearing = 9000.0f + atan2(-dLat, dLon) * 5729.57795f; //Convert the output redians to 100xdeg
if (*bearing < 0) *bearing += 36000;
}
#if defined(OBSOLATED)
////////////////////////////////////////////////////////////////////////////////////
// keep old calculation function for compatibility (could be removed later) distance in meters, bearing in degree
//
void GPS_distance(int32_t lat1, int32_t lon1, int32_t lat2, int32_t lon2, uint16_t* dist, int16_t* bearing) {
uint32_t d1;
int32_t d2;
GPS_distance_cm_bearing(&lat1,&lon1,&lat2,&lon2,&d1,&d2);
*dist = d1 / 100; //convert to meters
*bearing = d2 / 100; //convert to degrees
}
#endif
//*******************************************************************************************************
// calc_velocity_and_filtered_position - velocity in lon and lat directions calculated from GPS position
// and accelerometer data
// lon_speed expressed in cm/s. positive numbers mean moving east
// lat_speed expressed in cm/s. positive numbers when moving north
// Note: we use gps locations directly to calculate velocity instead of asking gps for velocity because
// this is more accurate below 1.5m/s
// Note: even though the positions are projected using a lead filter, the velocities are calculated
// from the unaltered gps locations. We do not want noise from our lead filter affecting velocity
//*******************************************************************************************************
static void GPS_calc_velocity(void){
static int16_t speed_old[2] = {0,0};
static int32_t last[2] = {0,0};
static uint8_t init = 0;
if (init) {
float tmp = 1.0/dTnav;
actual_speed[_X] = (float)(GPS_coord[LON] - last[LON]) * GPS_scaleLonDown * tmp;
actual_speed[_Y] = (float)(GPS_coord[LAT] - last[LAT]) * tmp;
#if !defined(GPS_LEAD_FILTER)
actual_speed[_X] = (actual_speed[_X] + speed_old[_X]) / 2;
actual_speed[_Y] = (actual_speed[_Y] + speed_old[_Y]) / 2;
speed_old[_X] = actual_speed[_X];
speed_old[_Y] = actual_speed[_Y];
#endif
}
init=1;
last[LON] = GPS_coord[LON];
last[LAT] = GPS_coord[LAT];
#if defined(GPS_LEAD_FILTER)
GPS_coord_lead[LON] = xLeadFilter.get_position(GPS_coord[LON], actual_speed[_X], GPS_LAG);
GPS_coord_lead[LAT] = yLeadFilter.get_position(GPS_coord[LAT], actual_speed[_Y], GPS_LAG);
#endif
}
////////////////////////////////////////////////////////////////////////////////////
// Calculate a location error between two gps coordinates
// Because we are using lat and lon to do our distance errors here's a quick chart:
// 100 = 1m
// 1000 = 11m = 36 feet
// 1800 = 19.80m = 60 feet
// 3000 = 33m
// 10000 = 111m
//
static void GPS_calc_location_error( int32_t* target_lat, int32_t* target_lng, int32_t* gps_lat, int32_t* gps_lng ) {
error[LON] = (float)(*target_lng - *gps_lng) * GPS_scaleLonDown; // X Error
error[LAT] = *target_lat - *gps_lat; // Y Error
}
////////////////////////////////////////////////////////////////////////////////////
// Calculate nav_lat and nav_lon from the x and y error and the speed
//
static void GPS_calc_poshold(void) {
int32_t d;
int32_t target_speed;
uint8_t axis;
for (axis=0;axis<2;axis++) {
target_speed = get_P(error[axis], &posholdPID_PARAM); // calculate desired speed from lat/lon error
target_speed = constrain(target_speed,-100,100); // Constrain the target speed in poshold mode to 1m/s it helps avoid runaways..
rate_error[axis] = target_speed - actual_speed[axis]; // calc the speed error
nav[axis] =
get_P(rate_error[axis], &poshold_ratePID_PARAM)
+get_I(rate_error[axis] + error[axis], &dTnav, &poshold_ratePID[axis], &poshold_ratePID_PARAM);
d = get_D(error[axis], &dTnav, &poshold_ratePID[axis], &poshold_ratePID_PARAM);
d = constrain(d, -2000, 2000);
// get rid of noise
if(abs(actual_speed[axis]) < 50) d = 0;
nav[axis] +=d;
nav[axis] = constrain(nav[axis], -NAV_BANK_MAX, NAV_BANK_MAX);
navPID[axis].integrator = poshold_ratePID[axis].integrator;
}
}
////////////////////////////////////////////////////////////////////////////////////
// Calculate the desired nav_lat and nav_lon for distance flying such as RTH
//
static void GPS_calc_nav_rate(uint16_t max_speed) {
float trig[2];
uint8_t axis;
// push us towards the original track
GPS_update_crosstrack();
// nav_bearing includes crosstrack
float temp = (9000l - nav_bearing) * RADX100;
trig[_X] = cos(temp);
trig[_Y] = sin(temp);
for (axis=0;axis<2;axis++) {
rate_error[axis] = (trig[axis] * max_speed) - actual_speed[axis];
rate_error[axis] = constrain(rate_error[axis], -1000, 1000);
// P + I + D
nav[axis] =
get_P(rate_error[axis], &navPID_PARAM)
+get_I(rate_error[axis], &dTnav, &navPID[axis], &navPID_PARAM)
+get_D(rate_error[axis], &dTnav, &navPID[axis], &navPID_PARAM);
nav[axis] = constrain(nav[axis], -NAV_BANK_MAX, NAV_BANK_MAX);
poshold_ratePID[axis].integrator = navPID[axis].integrator;
}
}
////////////////////////////////////////////////////////////////////////////////////
// Calculating cross track error, this tries to keep the copter on a direct line
// when flying to a waypoint.
//
static void GPS_update_crosstrack(void) {
if (abs(wrap_18000(target_bearing - original_target_bearing)) < 4500) { // If we are too far off or too close we don't do track following
float temp = (target_bearing - original_target_bearing) * RADX100;
crosstrack_error = sin(temp) * (wp_distance * CROSSTRACK_GAIN); // Meters we are off track line
nav_bearing = target_bearing + constrain(crosstrack_error, -3000, 3000);
nav_bearing = wrap_36000(nav_bearing);
}else{
nav_bearing = target_bearing;
}
}
////////////////////////////////////////////////////////////////////////////////////
// Determine desired speed when navigating towards a waypoint, also implement slow
// speed rampup when starting a navigation
//
// |< WP Radius
// 0 1 2 3 4 5 6 7 8m
// ...|...|...|...|...|...|...|...|
// 100 | 200 300 400cm/s
// | +|+
// |< we should slow to 1.5 m/s as we hit the target
//
static uint16_t GPS_calc_desired_speed(uint16_t max_speed, bool _slow) {
// max_speed is default 400 or 4m/s
if(_slow){
max_speed = min(max_speed, wp_distance / 2);
//max_speed = max(max_speed, 0);
}else{
max_speed = min(max_speed, wp_distance);
max_speed = max(max_speed, NAV_SPEED_MIN); // go at least 100cm/s
}
// limit the ramp up of the speed
// waypoint_speed_gov is reset to 0 at each new WP command
if(max_speed > waypoint_speed_gov){
waypoint_speed_gov += (int)(100.0 * dTnav); // increase at .5/ms
max_speed = waypoint_speed_gov;
}
return max_speed;
}
////////////////////////////////////////////////////////////////////////////////////
// Utilities
//
int32_t wrap_36000(int32_t ang) {
if (ang > 36000) ang -= 36000;
if (ang < 0) ang += 36000;
return ang;
}
// This code is used for parsing NMEA data
#if defined(GPS_SERIAL)
/* Alex optimization
The latitude or longitude is coded this way in NMEA frames
dm.f coded as degrees + minutes + minute decimal
Where:
- d can be 1 or more char long. generally: 2 char long for latitude, 3 char long for longitude
- m is always 2 char long
- f can be 1 or more char long
This function converts this format in a unique unsigned long where 1 degree = 10 000 000
EOS increased the precision here, even if we think that the gps is not precise enough, with 10e5 precision it has 76cm resolution
with 10e7 it's around 1 cm now. Increasing it further is irrelevant, since even 1cm resolution is unrealistic, however increased
resolution also increased precision of nav calculations
*/
/* This calc adds approc 2km error to the gps coordinates reverted back to the original working one
uint32_t GPS_coord_to_degrees(char* s) {
char *p = s, *d = s;
uint8_t min, deg = 0;
uint16_t frac = 0, mult = 10000;
while(*p) { // parse the string until its end
if (d != s) {frac+=(*p-'0')*mult;mult/=10;} // calculate only fractional part on up to 5 digits (d != s condition is true when the . is located)
if (*p == '.') d=p; // locate '.' char in the string
p++;
}
if (p==s) return 0;
while (s<d-2) {deg *= 10;deg += *(s++)-'0';} // convert degrees : all chars before minutes ; for the first iteration, deg = 0
min = *(d-1)-'0' + (*(d-2)-'0')*10; // convert minutes : 2 previous char before '.'
return deg * 10000000UL + (min * 100000UL + frac)*10UL / 6;
}
*/
#define DIGIT_TO_VAL(_x) (_x - '0')
uint32_t GPS_coord_to_degrees(char* s) {
char *p, *q;
uint8_t deg = 0, min = 0;
unsigned int frac_min = 0;
uint8_t i;
// scan for decimal point or end of field
for (p = s; isdigit(*p); p++) ;
q = s;
// convert degrees
while ((p - q) > 2) {
if (deg)
deg *= 10;
deg += DIGIT_TO_VAL(*q++);
}
// convert minutes
while (p > q) {
if (min)
min *= 10;
min += DIGIT_TO_VAL(*q++);
}
// convert fractional minutes
// expect up to four digits, result is in
// ten-thousandths of a minute
if (*p == '.') {
q = p + 1;
for (i = 0; i < 4; i++) {
frac_min *= 10;
if (isdigit(*q))
frac_min += *q++ - '0';
}
}
return deg * 10000000UL + (min * 1000000UL + frac_min*100UL) / 6;
}
// helper functions
uint16_t grab_fields(char* src, uint8_t mult) { // convert string to uint16
uint8_t i;
uint16_t tmp = 0;
for(i=0; src[i]!=0; i++) {
if(src[i] == '.') {
i++;
if(mult==0) break;
else src[i+mult] = 0;
}
tmp *= 10;
if(src[i] >='0' && src[i] <='9') tmp += src[i]-'0';
}
return tmp;
}
uint8_t hex_c(uint8_t n) { // convert '0'..'9','A'..'F' to 0..15
n -= '0';