/// -*- 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 or CH8_OPT parameter must be set to "Flip" (AUX_SWITCH_FLIP)
* Pilot switches to Stabilize, Acro or AltHold flight mode and puts ch7/ch8 switch to ON position
* Roll will be to the left is roll stick is held slightly left, otherwise it will roll right
* 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 170 // throttle increase during Flip_Start stage (under 45deg lean angle)
#define FLIP_THR_DEC 120 // throttle decrease during Flip_Roll stage (between 45deg ~ -90deg roll)
#define FLIP_ROLL_RATE 40000 // roll 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
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_dir; // roll direction (-1 = roll left, 1 = roll right)
// 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();
// choose direction based on pilot's roll stick
if (g.rc_1.control_in >= 0) {
flip_dir = FLIP_ROLL_RIGHT;
}else{
flip_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_abandon - pilot request to abandon flip
static void flip_stop()
{
// exit immediatley if not in flip mode
if (control_mode != FLIP) {
return;
}
// return to original flip mode
if (!set_mode(flip_orig_control_mode)) {
// this should never happen but just in case
set_mode(STABILIZE);
}
// log completion
Log_Write_Event(DATA_FLIP_END);
}
// flip_run - runs the flip controller
// should be called at 100hz or more
static void flip_run()
{
const Vector3f curr_ef_targets = attitude_control.angle_ef_targets(); // original earth-frame angle targets to recover
int16_t throttle_out;
// if pilot inputs roll > 40deg or timeout occurs abandon flip
if (!motors.armed() || (abs(g.rc_1.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 roll rate
int32_t roll_angle = ahrs.roll_sensor * flip_dir;
// state machine
switch (flip_state) {
case Flip_Start:
// under 45 degrees request 400deg/sec roll
attitude_control.rate_bf_roll_pitch_yaw(FLIP_ROLL_RATE * flip_dir, 0.0, 0.0);
// increase throttle
throttle_out += FLIP_THR_INC;
// beyond 45deg lean angle move to next stage
if (roll_angle >= 4500) {
flip_state = Flip_Roll;
}
break;
case Flip_Roll:
// between 45deg ~ -90deg request 400deg/sec roll
attitude_control.rate_bf_roll_pitch_yaw(FLIP_ROLL_RATE * flip_dir, 0.0, 0.0);
// decrease throttle
throttle_out -= FLIP_THR_DEC;
// beyond -90deg move on to recovery
if((roll_angle < 4500) && (roll_angle > -9000)) {
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 alitude
throttle_out += FLIP_THR_INC;
// check for successful recovery
if (fabs(flip_orig_attitude.x - (float)ahrs.roll_sensor) <= 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);
}