ardupilot/ArduPlane/Attitude.pde

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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
//****************************************************************
// Function that controls aileron/rudder, elevator, rudder (if 4 channel control) and throttle to produce desired attitude and airspeed.
//****************************************************************
static void stabilize()
{
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float ch1_inf = 1.0;
float ch2_inf = 1.0;
float ch4_inf = 1.0;
float speed_scaler;
float aspeed;
if (ahrs.airspeed_estimate(&aspeed)) {
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if (aspeed > 0) {
speed_scaler = g.scaling_speed / aspeed;
} else {
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speed_scaler = 2.0;
}
speed_scaler = constrain(speed_scaler, 0.5, 2.0);
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} else {
if (g.channel_throttle.servo_out > 0) {
speed_scaler = 0.5 + ((float)THROTTLE_CRUISE / g.channel_throttle.servo_out / 2.0); // First order taylor expansion of square root
// Should maybe be to the 2/7 power, but we aren't goint to implement that...
}else{
speed_scaler = 1.67;
}
// This case is constrained tighter as we don't have real speed info
speed_scaler = constrain(speed_scaler, 0.6, 1.67);
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}
if(crash_timer > 0) {
nav_roll_cd = 0;
}
if (inverted_flight) {
// we want to fly upside down. We need to cope with wrap of
// the roll_sensor interfering with wrap of nav_roll, which
// would really confuse the PID code. The easiest way to
// handle this is to ensure both go in the same direction from
// zero
nav_roll_cd += 18000;
if (ahrs.roll_sensor < 0) nav_roll_cd -= 36000;
}
#if APM_CONTROL == DISABLED
// Calculate dersired servo output for the roll
// ---------------------------------------------
g.channel_roll.servo_out = g.pidServoRoll.get_pid((nav_roll_cd - ahrs.roll_sensor), speed_scaler);
int32_t tempcalc = nav_pitch_cd +
fabs(ahrs.roll_sensor * g.kff_pitch_compensation) +
(g.channel_throttle.servo_out * g.kff_throttle_to_pitch) -
(ahrs.pitch_sensor - g.pitch_trim_cd);
if (inverted_flight) {
// when flying upside down the elevator control is inverted
tempcalc = -tempcalc;
}
g.channel_pitch.servo_out = g.pidServoPitch.get_pid(tempcalc, speed_scaler);
#else // APM_CONTROL == ENABLED
// calculate roll and pitch control using new APM_Control library
g.channel_roll.servo_out = g.rollController.get_servo_out(nav_roll_cd, speed_scaler, control_mode == STABILIZE);
g.channel_pitch.servo_out = g.pitchController.get_servo_out(nav_pitch_cd, speed_scaler, control_mode == STABILIZE);
#endif
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// Mix Stick input to allow users to override control surfaces
// -----------------------------------------------------------
if ((control_mode < FLY_BY_WIRE_A) ||
(g.stick_mixing &&
geofence_stickmixing() &&
control_mode > FLY_BY_WIRE_B &&
failsafe == FAILSAFE_NONE)) {
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// TODO: use RC_Channel control_mix function?
ch1_inf = (float)g.channel_roll.radio_in - (float)g.channel_roll.radio_trim;
ch1_inf = fabs(ch1_inf);
ch1_inf = min(ch1_inf, 400.0);
ch1_inf = ((400.0 - ch1_inf) /400.0);
ch2_inf = (float)g.channel_pitch.radio_in - g.channel_pitch.radio_trim;
ch2_inf = fabs(ch2_inf);
ch2_inf = min(ch2_inf, 400.0);
ch2_inf = ((400.0 - ch2_inf) /400.0);
// scale the sensor input based on the stick input
// -----------------------------------------------
g.channel_roll.servo_out *= ch1_inf;
g.channel_pitch.servo_out *= ch2_inf;
// Mix in stick inputs
// -------------------
g.channel_roll.servo_out += g.channel_roll.pwm_to_angle();
g.channel_pitch.servo_out += g.channel_pitch.pwm_to_angle();
//Serial.printf_P(PSTR(" servo_out[CH_ROLL] "));
//Serial.println(servo_out[CH_ROLL],DEC);
}
// stick mixing performed for rudder for all cases including FBW unless disabled for higher modes
// important for steering on the ground during landing
// -----------------------------------------------
if (control_mode <= FLY_BY_WIRE_B ||
(g.stick_mixing &&
geofence_stickmixing() &&
failsafe == FAILSAFE_NONE)) {
ch4_inf = (float)g.channel_rudder.radio_in - (float)g.channel_rudder.radio_trim;
ch4_inf = fabs(ch4_inf);
ch4_inf = min(ch4_inf, 400.0);
ch4_inf = ((400.0 - ch4_inf) /400.0);
}
// Apply output to Rudder
// ----------------------
calc_nav_yaw(speed_scaler, ch4_inf);
g.channel_rudder.servo_out *= ch4_inf;
g.channel_rudder.servo_out += g.channel_rudder.pwm_to_angle();
// Call slew rate limiter if used
// ------------------------------
//#if(ROLL_SLEW_LIMIT != 0)
// g.channel_roll.servo_out = roll_slew_limit(g.channel_roll.servo_out);
//#endif
}
static void crash_checker()
{
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if(ahrs.pitch_sensor < -4500) {
crash_timer = 255;
}
if(crash_timer > 0)
crash_timer--;
}
static void calc_throttle()
{
if (!alt_control_airspeed()) {
int16_t throttle_target = g.throttle_cruise + throttle_nudge;
// TODO: think up an elegant way to bump throttle when
// groundspeed_undershoot > 0 in the no airspeed sensor case; PID
// control?
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// no airspeed sensor, we use nav pitch to determine the proper throttle output
// AUTO, RTL, etc
// ---------------------------------------------------------------------------
if (nav_pitch_cd >= 0) {
g.channel_throttle.servo_out = throttle_target + (g.throttle_max - throttle_target) * nav_pitch_cd / g.pitch_limit_max_cd;
} else {
g.channel_throttle.servo_out = throttle_target - (throttle_target - g.throttle_min) * nav_pitch_cd / g.pitch_limit_min_cd;
}
g.channel_throttle.servo_out = constrain(g.channel_throttle.servo_out, g.throttle_min.get(), g.throttle_max.get());
} else {
// throttle control with airspeed compensation
// -------------------------------------------
energy_error = airspeed_energy_error + altitude_error_cm * 0.098f;
// positive energy errors make the throttle go higher
g.channel_throttle.servo_out = g.throttle_cruise + g.pidTeThrottle.get_pid(energy_error);
g.channel_throttle.servo_out += (g.channel_pitch.servo_out * g.kff_pitch_to_throttle);
g.channel_throttle.servo_out = constrain(g.channel_throttle.servo_out,
g.throttle_min.get(), g.throttle_max.get());
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}
}
/*****************************************
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* Calculate desired roll/pitch/yaw angles (in medium freq loop)
*****************************************/
// Yaw is separated into a function for future implementation of heading hold on rolling take-off
// ----------------------------------------------------------------------------------------
static void calc_nav_yaw(float speed_scaler, float ch4_inf)
{
if (hold_course != -1) {
// steering on or close to ground
g.channel_rudder.servo_out = g.pidWheelSteer.get_pid(bearing_error_cd) + g.kff_rudder_mix * g.channel_roll.servo_out;
return;
}
#if APM_CONTROL == DISABLED
// always do rudder mixing from roll
g.channel_rudder.servo_out = g.kff_rudder_mix * g.channel_roll.servo_out;
// a PID to coordinate the turn (drive y axis accel to zero)
Vector3f temp = imu.get_accel();
int32_t error = -temp.y*100.0;
g.channel_rudder.servo_out += g.pidServoRudder.get_pid(error, speed_scaler);
#else // APM_CONTROL == ENABLED
// use the new APM_Control library
g.channel_rudder.servo_out = g.yawController.get_servo_out(speed_scaler, ch4_inf < 0.25) + g.channel_roll.servo_out * g.kff_rudder_mix;
#endif
}
static void calc_nav_pitch()
{
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// Calculate the Pitch of the plane
// --------------------------------
if (alt_control_airspeed()) {
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nav_pitch_cd = -g.pidNavPitchAirspeed.get_pid(airspeed_error_cm);
} else {
nav_pitch_cd = g.pidNavPitchAltitude.get_pid(altitude_error_cm);
}
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nav_pitch_cd = constrain(nav_pitch_cd, g.pitch_limit_min_cd.get(), g.pitch_limit_max_cd.get());
}
static void calc_nav_roll()
{
#define NAV_ROLL_BY_RATE 0
#if NAV_ROLL_BY_RATE
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// Scale from centidegrees (PID input) to radians per second. A P gain of 1.0 should result in a
// desired rate of 1 degree per second per degree of error - if you're 15 degrees off, you'll try
// to turn at 15 degrees per second.
float turn_rate = ToRad(g.pidNavRoll.get_pid(bearing_error_cd) * .01);
// Use airspeed_cruise as an analogue for airspeed if we don't have airspeed.
float speed;
if(airspeed.use()) {
speed = airspeed.get_airspeed();
} else {
speed = g.airspeed_cruise_cm*0.01;
// Floor the speed so that the user can't enter a bad value
if(speed < 6) {
speed = 6;
}
}
// Bank angle = V*R/g, where V is airspeed, R is turn rate, and g is gravity.
nav_roll = ToDeg(atan(speed*turn_rate/9.81)*100);
#else
// this is the old nav_roll calculation. We will use this for 2.50
// then remove for a future release
float nav_gain_scaler = 0.01 * g_gps->ground_speed / g.scaling_speed;
nav_gain_scaler = constrain(nav_gain_scaler, 0.2, 1.4);
nav_roll_cd = g.pidNavRoll.get_pid(bearing_error_cd, nav_gain_scaler); //returns desired bank angle in degrees*100
#endif
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nav_roll_cd = constrain(nav_roll_cd, -g.roll_limit_cd.get(), g.roll_limit_cd.get());
}
/*****************************************
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* Roll servo slew limit
*****************************************/
/*
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* float roll_slew_limit(float servo)
* {
* static float last;
* float temp = constrain(servo, last-ROLL_SLEW_LIMIT * delta_ms_fast_loop/1000.f, last + ROLL_SLEW_LIMIT * delta_ms_fast_loop/1000.f);
* last = servo;
* return temp;
* }*/
/*****************************************
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* Throttle slew limit
*****************************************/
static void throttle_slew_limit()
{
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static int16_t last = 1000;
if(g.throttle_slewrate) { // if slew limit rate is set to zero then do not slew limit
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float temp = g.throttle_slewrate * G_Dt * 10.f; // * 10 to scale % to pwm range of 1000 to 2000
g.channel_throttle.radio_out = constrain(g.channel_throttle.radio_out, last - (int)temp, last + (int)temp);
last = g.channel_throttle.radio_out;
}
}
/* We want to supress the throttle if we think we are on the ground and in an autopilot controlled throttle mode.
Disable throttle if following conditions are met:
* 1 - We are in Circle mode (which we use for short term failsafe), or in FBW-B or higher
* AND
* 2 - Our reported altitude is within 10 meters of the home altitude.
* 3 - Our reported speed is under 5 meters per second.
* 4 - We are not performing a takeoff in Auto mode
* OR
* 5 - Home location is not set
*/
static bool suppress_throttle(void)
{
if (!throttle_suppressed) {
// we've previously met a condition for unsupressing the throttle
return false;
}
if (control_mode != CIRCLE && control_mode <= FLY_BY_WIRE_A) {
// the user controls the throttle
throttle_suppressed = false;
return false;
}
if (control_mode==AUTO && takeoff_complete == false) {
// we're in auto takeoff
throttle_suppressed = false;
return false;
}
if (labs(home.alt - current_loc.alt) >= 1000) {
// we're more than 10m from the home altitude
throttle_suppressed = false;
return false;
}
if (g_gps != NULL &&
g_gps->status() == GPS::GPS_OK &&
g_gps->ground_speed >= 500) {
// we're moving at more than 5 m/s
throttle_suppressed = false;
return false;
}
// throttle remains suppressed
return true;
}
/*****************************************
* Set the flight control servos based on the current calculated values
*****************************************/
static void set_servos(void)
{
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int16_t flapSpeedSource = 0;
// vectorize the rc channels
RC_Channel_aux* rc_array[NUM_CHANNELS];
rc_array[CH_1] = NULL;
rc_array[CH_2] = NULL;
rc_array[CH_3] = NULL;
rc_array[CH_4] = NULL;
rc_array[CH_5] = &g.rc_5;
rc_array[CH_6] = &g.rc_6;
rc_array[CH_7] = &g.rc_7;
rc_array[CH_8] = &g.rc_8;
if(control_mode == MANUAL) {
// do a direct pass through of radio values
if (g.mix_mode == 0) {
g.channel_roll.radio_out = g.channel_roll.radio_in;
g.channel_pitch.radio_out = g.channel_pitch.radio_in;
} else {
g.channel_roll.radio_out = APM_RC.InputCh(CH_ROLL);
g.channel_pitch.radio_out = APM_RC.InputCh(CH_PITCH);
}
g.channel_throttle.radio_out = g.channel_throttle.radio_in;
g.channel_rudder.radio_out = g.channel_rudder.radio_in;
// FIXME To me it does not make sense to control the aileron using radio_in in manual mode
// Doug could you please take a look at this ?
if (g_rc_function[RC_Channel_aux::k_aileron]) {
if (g_rc_function[RC_Channel_aux::k_aileron] != rc_array[g.flight_mode_channel-1]) {
g_rc_function[RC_Channel_aux::k_aileron]->radio_out = g_rc_function[RC_Channel_aux::k_aileron]->radio_in;
}
}
// only use radio_in if the channel is not used as flight_mode_channel
if (g_rc_function[RC_Channel_aux::k_flap_auto]) {
if (g_rc_function[RC_Channel_aux::k_flap_auto] != rc_array[g.flight_mode_channel-1]) {
g_rc_function[RC_Channel_aux::k_flap_auto]->radio_out = g_rc_function[RC_Channel_aux::k_flap_auto]->radio_in;
} else {
g_rc_function[RC_Channel_aux::k_flap_auto]->radio_out = g_rc_function[RC_Channel_aux::k_flap_auto]->radio_trim;
}
}
} else {
if (g.mix_mode == 0) {
if (g_rc_function[RC_Channel_aux::k_aileron]) {
g_rc_function[RC_Channel_aux::k_aileron]->servo_out = g.channel_roll.servo_out;
g_rc_function[RC_Channel_aux::k_aileron]->calc_pwm();
}
}else{
/*Elevon mode*/
float ch1;
float ch2;
ch1 = g.channel_pitch.servo_out - (BOOL_TO_SIGN(g.reverse_elevons) * g.channel_roll.servo_out);
ch2 = g.channel_pitch.servo_out + (BOOL_TO_SIGN(g.reverse_elevons) * g.channel_roll.servo_out);
g.channel_roll.radio_out = elevon1_trim + (BOOL_TO_SIGN(g.reverse_ch1_elevon) * (ch1 * 500.0/ SERVO_MAX));
g.channel_pitch.radio_out = elevon2_trim + (BOOL_TO_SIGN(g.reverse_ch2_elevon) * (ch2 * 500.0/ SERVO_MAX));
}
#if THROTTLE_OUT == 0
g.channel_throttle.servo_out = 0;
#else
// convert 0 to 100% into PWM
g.channel_throttle.servo_out = constrain(g.channel_throttle.servo_out, g.throttle_min.get(), g.throttle_max.get());
if (suppress_throttle()) {
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g.channel_throttle.servo_out = 0;
}
#endif
if (control_mode >= FLY_BY_WIRE_B) {
/* only do throttle slew limiting in modes where throttle
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* control is automatic */
throttle_slew_limit();
}
#if OBC_FAILSAFE == ENABLED
// this is to allow the failsafe module to deliberately crash
// the plane. Only used in extreme circumstances to meet the
// OBC rules
if (obc.crash_plane()) {
g.channel_roll.servo_out = -4500;
g.channel_pitch.servo_out = -4500;
g.channel_rudder.servo_out = -4500;
g.channel_throttle.servo_out = 0;
}
#endif
// push out the PWM values
g.channel_roll.calc_pwm();
g.channel_pitch.calc_pwm();
g.channel_throttle.calc_pwm();
g.channel_rudder.calc_pwm();
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}
// Auto flap deployment
if (g_rc_function[RC_Channel_aux::k_flap_auto] != NULL) {
if(control_mode < FLY_BY_WIRE_B) {
// only use radio_in if the channel is not used as flight_mode_channel
if (g_rc_function[RC_Channel_aux::k_flap_auto] != rc_array[g.flight_mode_channel-1]) {
g_rc_function[RC_Channel_aux::k_flap_auto]->radio_out = g_rc_function[RC_Channel_aux::k_flap_auto]->radio_in;
} else {
g_rc_function[RC_Channel_aux::k_flap_auto]->radio_out = g_rc_function[RC_Channel_aux::k_flap_auto]->radio_trim;
}
} else if (control_mode >= FLY_BY_WIRE_B) {
// FIXME: use target_airspeed in both FBW_B and g.airspeed_enabled cases - Doug?
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if (control_mode == FLY_BY_WIRE_B) {
flapSpeedSource = target_airspeed_cm * 0.01;
} else if (airspeed.use()) {
flapSpeedSource = g.airspeed_cruise_cm * 0.01;
} else {
flapSpeedSource = g.throttle_cruise;
}
if ( g.flap_1_speed != 0 && flapSpeedSource > g.flap_1_speed) {
g_rc_function[RC_Channel_aux::k_flap_auto]->servo_out = 0;
} else if (g.flap_2_speed != 0 && flapSpeedSource > g.flap_2_speed) {
g_rc_function[RC_Channel_aux::k_flap_auto]->servo_out = g.flap_1_percent;
} else {
g_rc_function[RC_Channel_aux::k_flap_auto]->servo_out = g.flap_2_percent;
}
g_rc_function[RC_Channel_aux::k_flap_auto]->calc_pwm();
}
}
#if HIL_MODE == HIL_MODE_DISABLED || HIL_SERVOS
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// send values to the PWM timers for output
// ----------------------------------------
APM_RC.OutputCh(CH_1, g.channel_roll.radio_out); // send to Servos
APM_RC.OutputCh(CH_2, g.channel_pitch.radio_out); // send to Servos
APM_RC.OutputCh(CH_3, g.channel_throttle.radio_out); // send to Servos
APM_RC.OutputCh(CH_4, g.channel_rudder.radio_out); // send to Servos
// Route configurable aux. functions to their respective servos
g.rc_5.output_ch(CH_5);
g.rc_6.output_ch(CH_6);
g.rc_7.output_ch(CH_7);
g.rc_8.output_ch(CH_8);
# if CONFIG_APM_HARDWARE != APM_HARDWARE_APM1
g.rc_9.output_ch(CH_9);
g.rc_10.output_ch(CH_10);
g.rc_11.output_ch(CH_11);
# endif
#endif
}
static void demo_servos(byte i) {
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while(i > 0) {
gcs_send_text_P(SEVERITY_LOW,PSTR("Demo Servos!"));
#if HIL_MODE == HIL_MODE_DISABLED || HIL_SERVOS
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APM_RC.OutputCh(1, 1400);
mavlink_delay(400);
APM_RC.OutputCh(1, 1600);
mavlink_delay(200);
APM_RC.OutputCh(1, 1500);
#endif
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mavlink_delay(400);
i--;
}
}
// return true if we should use airspeed for altitude/throttle control
static bool alt_control_airspeed(void)
{
return airspeed.use() && g.alt_control_algorithm == ALT_CONTROL_DEFAULT;
}