ardupilot/ArduCopter/control_drift.pde

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/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
* control_drift.pde - init and run calls for drift flight mode
*/
#ifndef DRIFT_SPEEDGAIN
# define DRIFT_SPEEDGAIN 8.0f
#endif
#ifndef DRIFT_SPEEDLIMIT
# define DRIFT_SPEEDLIMIT 560.0f
#endif
#ifndef DRIFT_THR_ASSIST_GAIN
# define DRIFT_THR_ASSIST_GAIN 1.8f // gain controlling amount of throttle assistance
#endif
#ifndef DRIFT_THR_ASSIST_MAX
# define DRIFT_THR_ASSIST_MAX 300.0f // maximum assistance throttle assist will provide
#endif
#ifndef DRIFT_THR_MIN
# define DRIFT_THR_MIN 213 // throttle assist will be active when pilot's throttle is above this value
#endif
#ifndef DRIFT_THR_MAX
# define DRIFT_THR_MAX 787 // throttle assist will be active when pilot's throttle is below this value
#endif
// drift_init - initialise drift controller
static bool drift_init(bool ignore_checks)
{
if (position_ok() || ignore_checks) {
return true;
}else{
return false;
}
}
// drift_run - runs the drift controller
// should be called at 100hz or more
static void drift_run()
{
static float breaker = 0.0;
static float roll_input = 0.0;
float target_roll, target_pitch;
float target_yaw_rate;
int16_t pilot_throttle_scaled;
// if not armed or landed and throttle at zero, set throttle to zero and exit immediately
if(!motors.armed() || (ap.land_complete && ap.throttle_zero)) {
attitude_control.set_throttle_out_unstabilized(0,true,g.throttle_filt);
return;
}
// convert pilot input to lean angles
get_pilot_desired_lean_angles(g.rc_1.control_in, g.rc_2.control_in, target_roll, target_pitch);
// get pilot's desired throttle
pilot_throttle_scaled = get_pilot_desired_throttle(g.rc_3.control_in);
// Grab inertial velocity
const Vector3f& vel = inertial_nav.get_velocity();
// rotate roll, pitch input from north facing to vehicle's perspective
float roll_vel = vel.y * ahrs.cos_yaw() - vel.x * ahrs.sin_yaw(); // body roll vel
float pitch_vel = vel.y * ahrs.sin_yaw() + vel.x * ahrs.cos_yaw(); // body pitch vel
// gain sceduling for Yaw
float pitch_vel2 = min(fabs(pitch_vel), 2000);
target_yaw_rate = ((float)target_roll/1.0f) * (1.0f - (pitch_vel2 / 5000.0f)) * g.acro_yaw_p;
roll_vel = constrain_float(roll_vel, -DRIFT_SPEEDLIMIT, DRIFT_SPEEDLIMIT);
pitch_vel = constrain_float(pitch_vel, -DRIFT_SPEEDLIMIT, DRIFT_SPEEDLIMIT);
roll_input = roll_input * .96 + (float)g.rc_4.control_in * .04;
//convert user input into desired roll velocity
float roll_vel_error = roll_vel - (roll_input / DRIFT_SPEEDGAIN);
// Roll velocity is feed into roll acceleration to minimize slip
target_roll = roll_vel_error * -DRIFT_SPEEDGAIN;
target_roll = constrain_int16(target_roll, -4500, 4500);
// If we let go of sticks, bring us to a stop
if(target_pitch == 0){
// .14/ (.03 * 100) = 4.6 seconds till full breaking
breaker += .03;
breaker = min(breaker, DRIFT_SPEEDGAIN);
target_pitch = pitch_vel * breaker;
}else{
breaker = 0.0;
}
// call attitude controller
attitude_control.angle_ef_roll_pitch_rate_ef_yaw_smooth(target_roll, target_pitch, target_yaw_rate, get_smoothing_gain());
// output pilot's throttle with angle boost
attitude_control.set_throttle_out(get_throttle_assist(vel.z, pilot_throttle_scaled), true, g.throttle_filt);
}
// get_throttle_assist - return throttle output (range 0 ~ 1000) based on pilot input and z-axis velocity
int16_t get_throttle_assist(float velz, int16_t pilot_throttle_scaled)
{
// throttle assist - adjusts throttle to slow the vehicle's vertical velocity
// Only active when pilot's throttle is between 213 ~ 787
// Assistance is strongest when throttle is at mid, drops linearly to no assistance at 213 and 787
float thr_assist = 0.0f;
if (pilot_throttle_scaled > g.throttle_min && pilot_throttle_scaled < THR_MAX &&
pilot_throttle_scaled > DRIFT_THR_MIN && pilot_throttle_scaled < DRIFT_THR_MAX) {
// calculate throttle assist gain
thr_assist = 1.2 - ((float)abs(pilot_throttle_scaled - 500) / 240.0f);
thr_assist = constrain_float(thr_assist, 0.0f, 1.0f) * -DRIFT_THR_ASSIST_GAIN * velz;
// ensure throttle assist never adjusts the throttle by more than 300 pwm
thr_assist = constrain_float(thr_assist, -DRIFT_THR_ASSIST_MAX, DRIFT_THR_ASSIST_MAX);
// ensure throttle assist never pushes throttle below throttle_min or above throttle_max
thr_assist = constrain_float(thr_assist, g.throttle_min - pilot_throttle_scaled, THR_MAX - pilot_throttle_scaled);
}
return pilot_throttle_scaled + thr_assist;
}