ardupilot/ArduCopter/control_flip.pde

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/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
* control_flip.pde - init and run calls for flip flight mode
* original implementation in 2010 by Jose Julio
* Adapted and updated for AC2 in 2011 by Jason Short
*
* Controls:
* CH7_OPT - CH12_OPT parameter must be set to "Flip" (AUXSW_FLIP) which is "2"
* Pilot switches to Stabilize, Acro or AltHold flight mode and puts ch7/ch8 switch to ON position
* Vehicle will Roll right by default but if roll or pitch stick is held slightly left, forward or back it will flip in that direction
* Vehicle should complete the roll within 2.5sec and will then return to the original flight mode it was in before flip was triggered
* Pilot may manually exit flip by switching off ch7/ch8 or by moving roll stick to >40deg left or right
*
* State machine approach:
* Flip_Start (while copter is leaning <45deg) : roll right at 400deg/sec, increase throttle
* Flip_Roll (while copter is between +45deg ~ -90) : roll right at 400deg/sec, reduce throttle
* Flip_Recover (while copter is between -90deg and original target angle) : use earth frame angle controller to return vehicle to original attitude
*/
#define FLIP_THR_INC 200 // throttle increase during Flip_Start stage (under 45deg lean angle)
#define FLIP_THR_DEC 240 // throttle decrease during Flip_Roll stage (between 45deg ~ -90deg roll)
#define FLIP_ROTATION_RATE 40000 // rotation rate request in centi-degrees / sec (i.e. 400 deg/sec)
#define FLIP_TIMEOUT_MS 2500 // timeout after 2.5sec. Vehicle will switch back to original flight mode
#define FLIP_RECOVERY_ANGLE 500 // consider successful recovery when roll is back within 5 degrees of original
#define FLIP_ROLL_RIGHT 1 // used to set flip_dir
#define FLIP_ROLL_LEFT -1 // used to set flip_dir
#define FLIP_PITCH_BACK 1 // used to set flip_dir
#define FLIP_PITCH_FORWARD -1 // used to set flip_dir
FlipState flip_state; // current state of flip
uint8_t flip_orig_control_mode; // flight mode when flip was initated
uint32_t flip_start_time; // time since flip began
int8_t flip_roll_dir; // roll direction (-1 = roll left, 1 = roll right)
int8_t flip_pitch_dir; // pitch direction (-1 = pitch forward, 1 = pitch back)
// flip_init - initialise flip controller
static bool flip_init(bool ignore_checks)
{
// only allow flip from ACRO, Stabilize, AltHold or Drift flight modes
if (control_mode != ACRO && control_mode != STABILIZE && control_mode != ALT_HOLD) {
return false;
}
// if in acro or stabilize ensure throttle is above zero
if ((g.rc_3.control_in <= 0) && (control_mode == ACRO || control_mode == STABILIZE)) {
return false;
}
// ensure roll input is less than 40deg
if (abs(g.rc_1.control_in) >= 4000) {
return false;
}
// only allow flip when flying
if (!motors.armed() || ap.land_complete) {
return false;
}
// capture original flight mode so that we can return to it after completion
flip_orig_control_mode = control_mode;
// initialise state
flip_state = Flip_Start;
flip_start_time = millis();
flip_roll_dir = flip_pitch_dir = 0;
// choose direction based on pilot's roll and pitch sticks
if (g.rc_2.control_in > 300) {
flip_pitch_dir = FLIP_PITCH_BACK;
}else if(g.rc_2.control_in < -300) {
flip_pitch_dir = FLIP_PITCH_FORWARD;
}else if (g.rc_1.control_in >= 0) {
flip_roll_dir = FLIP_ROLL_RIGHT;
}else{
flip_roll_dir = FLIP_ROLL_LEFT;
}
// log start of flip
Log_Write_Event(DATA_FLIP_START);
// capture current attitude which will be used during the Flip_Recovery stage
flip_orig_attitude.x = constrain_float(ahrs.roll_sensor, -aparm.angle_max, aparm.angle_max);
flip_orig_attitude.y = constrain_float(ahrs.pitch_sensor, -aparm.angle_max, aparm.angle_max);
flip_orig_attitude.z = ahrs.yaw_sensor;
return true;
}
// flip_run - runs the flip controller
// should be called at 100hz or more
static void flip_run()
{
int16_t throttle_out;
float recovery_angle;
// if pilot inputs roll > 40deg or timeout occurs abandon flip
if (!motors.armed() || (abs(g.rc_1.control_in) >= 4000) || (abs(g.rc_2.control_in) >= 4000) || ((millis() - flip_start_time) > FLIP_TIMEOUT_MS)) {
flip_state = Flip_Abandon;
}
// get pilot's desired throttle
throttle_out = get_pilot_desired_throttle(g.rc_3.control_in);
// get corrected angle based on direction and axis of rotation
// we flip the sign of flip_angle to minimize the code repetition
int32_t flip_angle;
if (flip_roll_dir != 0) {
flip_angle = ahrs.roll_sensor * flip_roll_dir;
} else {
flip_angle = ahrs.pitch_sensor * flip_pitch_dir;
}
// state machine
switch (flip_state) {
case Flip_Start:
// under 45 degrees request 400deg/sec roll or pitch
attitude_control.rate_bf_roll_pitch_yaw(FLIP_ROTATION_RATE * flip_roll_dir, FLIP_ROTATION_RATE * flip_pitch_dir, 0.0);
// increase throttle
throttle_out += FLIP_THR_INC;
// beyond 45deg lean angle move to next stage
if (flip_angle >= 4500) {
if (flip_roll_dir != 0) {
// we are rolling
flip_state = Flip_Roll;
} else {
// we are pitching
flip_state = Flip_Pitch_A;
}
}
break;
case Flip_Roll:
// between 45deg ~ -90deg request 400deg/sec roll
attitude_control.rate_bf_roll_pitch_yaw(FLIP_ROTATION_RATE * flip_roll_dir, 0.0, 0.0);
// decrease throttle
if (throttle_out >= g.throttle_min) {
throttle_out = max(throttle_out - FLIP_THR_DEC, g.throttle_min);
}
// beyond -90deg move on to recovery
if ((flip_angle < 4500) && (flip_angle > -9000)) {
flip_state = Flip_Recover;
}
break;
case Flip_Pitch_A:
// between 45deg ~ -90deg request 400deg/sec pitch
attitude_control.rate_bf_roll_pitch_yaw(0.0, FLIP_ROTATION_RATE * flip_pitch_dir, 0.0);
// decrease throttle
if (throttle_out >= g.throttle_min) {
throttle_out = max(throttle_out - FLIP_THR_DEC, g.throttle_min);
}
// check roll for inversion
if ((labs(ahrs.roll_sensor) > 9000) && (flip_angle > 4500)) {
flip_state = Flip_Pitch_B;
}
break;
case Flip_Pitch_B:
// between 45deg ~ -90deg request 400deg/sec pitch
attitude_control.rate_bf_roll_pitch_yaw(0.0, FLIP_ROTATION_RATE * flip_pitch_dir, 0.0);
// decrease throttle
if (throttle_out >= g.throttle_min) {
throttle_out = max(throttle_out - FLIP_THR_DEC, g.throttle_min);
}
// check roll for inversion
if ((labs(ahrs.roll_sensor) < 9000) && (flip_angle > -4500)) {
flip_state = Flip_Recover;
}
break;
case Flip_Recover:
// use originally captured earth-frame angle targets to recover
attitude_control.angle_ef_roll_pitch_yaw(flip_orig_attitude.x, flip_orig_attitude.y, flip_orig_attitude.z, false);
// increase throttle to gain any lost altitude
throttle_out += FLIP_THR_INC;
if (flip_roll_dir != 0) {
// we are rolling
recovery_angle = fabs(flip_orig_attitude.x - (float)ahrs.roll_sensor);
} else {
// we are pitching
recovery_angle = fabs(flip_orig_attitude.y - (float)ahrs.pitch_sensor);
}
// check for successful recovery
if (fabs(recovery_angle) <= FLIP_RECOVERY_ANGLE) {
// restore original flight mode
if (!set_mode(flip_orig_control_mode)) {
// this should never happen but just in case
set_mode(STABILIZE);
}
// log successful completion
Log_Write_Event(DATA_FLIP_END);
}
break;
case Flip_Abandon:
// restore original flight mode
if (!set_mode(flip_orig_control_mode)) {
// this should never happen but just in case
set_mode(STABILIZE);
}
// log abandoning flip
Log_Write_Error(ERROR_SUBSYSTEM_FLIP,ERROR_CODE_FLIP_ABANDONED);
break;
}
// output pilot's throttle without angle boost
attitude_control.set_throttle_out(throttle_out, false);
}