mirror of https://github.com/ArduPilot/ardupilot
GPS: support getting raw velocity values from a UBlox
this may give better velocity numbers than the value from COG
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@ -242,6 +242,10 @@ AP_GPS_UBLOX::_parse_gps(void)
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speed_3d = _buffer.velned.speed_3d; // cm/s
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ground_speed = _buffer.velned.speed_2d; // cm/s
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ground_course = _buffer.velned.heading_2d / 1000; // Heading 2D deg * 100000 rescaled to deg * 100
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_have_raw_velocity = true;
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_vel_north = _buffer.velned.ned_north;
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_vel_east = _buffer.velned.ned_east;
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_vel_down = _buffer.velned.ned_down;
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_new_speed = true;
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break;
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default:
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@ -52,36 +52,23 @@ GPS::update(void)
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_idleTimer = tnow;
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if (_status == GPS_OK) {
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// update our acceleration
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float deltat = 1.0e-3 * (_idleTimer - last_fix_time);
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float deltav = 1.0e-2 * ((float)ground_speed - (float)_last_ground_speed_cm);
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float gps_heading = ToRad(ground_course * 0.01);
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float gps_speed = ground_speed * 0.01;
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float sin_heading, cos_heading;
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cos_heading = cos(gps_heading);
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sin_heading = sin(gps_heading);
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last_fix_time = _idleTimer;
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_last_ground_speed_cm = ground_speed;
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_velocity_north = gps_speed * cos_heading;
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_velocity_east = gps_speed * sin_heading;
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if (deltat > 2.0 || deltat == 0) {
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// we didn't get a fix for 2 seconds - set
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// acceleration to zero, as the estimate will be too
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// far out
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_acceleration = 0;
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_acceleration_north = 0;
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_acceleration_east = 0;
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if (_have_raw_velocity) {
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// the GPS is able to give us velocity numbers directly
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_velocity_north = _vel_north * 0.01;
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_velocity_east = _vel_east * 0.01;
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} else {
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// calculate a mildly smoothed acceleration value
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_acceleration = (0.7 * _acceleration) + (0.3 * (deltav/deltat));
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float gps_heading = ToRad(ground_course * 0.01);
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float gps_speed = ground_speed * 0.01;
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float sin_heading, cos_heading;
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// calculate the components, to save time in the AHRS code
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_acceleration_north = _acceleration * cos_heading;
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_acceleration_east = _acceleration * sin_heading;
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cos_heading = cos(gps_heading);
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sin_heading = sin(gps_heading);
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_velocity_north = gps_speed * cos_heading;
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_velocity_east = gps_speed * sin_heading;
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}
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}
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}
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@ -123,13 +123,6 @@ public:
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///
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uint32_t idleTimeout;
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// our approximate linear acceleration in m/s/s
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float acceleration(void) { return _acceleration; }
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// components of acceleration in 2D, in m/s/s
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float acceleration_north(void) { return _status == GPS_OK? _acceleration_north : 0; }
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float acceleration_east(void) { return _status == GPS_OK? _acceleration_east : 0; }
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// components of velocity in 2D, in m/s
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float velocity_north(void) { return _status == GPS_OK? _velocity_north : 0; }
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float velocity_east(void) { return _status == GPS_OK? _velocity_east : 0; }
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@ -196,6 +189,14 @@ protected:
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void _write_progstr_block(Stream *_fs, const prog_char *pstr, uint8_t size);
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// velocities in cm/s if available from the GPS
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int32_t _vel_north;
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int32_t _vel_east;
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int32_t _vel_down;
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// does this GPS support raw velocity numbers?
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bool _have_raw_velocity;
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private:
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@ -209,15 +210,9 @@ private:
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// previous ground speed in cm/s
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uint32_t _last_ground_speed_cm;
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// smoothed estimate of our acceleration, in m/s/s
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float _acceleration;
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float _acceleration_north;
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float _acceleration_east;
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// components of the velocity, in m/s
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float _velocity_north;
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float _velocity_east;
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};
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inline long
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@ -45,6 +45,10 @@ void loop()
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Serial.print(gps.ground_speed / 100.0);
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Serial.print(" COG:");
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Serial.print(gps.ground_course / 100.0, DEC);
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Serial.printf(" VEL: %.2f %.2f %.2f",
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gps.velocity_north(),
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gps.velocity_east(),
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sqrt(sq(gps.velocity_north())+sq(gps.velocity_east())));
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Serial.print(" SAT:");
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Serial.print(gps.num_sats, DEC);
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Serial.print(" FIX:");
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