ArduCopter/mode_drift.cpp

   1 #include "Copter.h"
   2
   3 #if MODE_DRIFT_ENABLED
   4
   5 /*
   6  * Init and run calls for drift flight mode
   7  */
   8
   9 #ifndef DRIFT_SPEEDGAIN
  10  # define DRIFT_SPEEDGAIN 8.0f
  11 #endif
  12 #ifndef DRIFT_SPEEDLIMIT
  13  # define DRIFT_SPEEDLIMIT 560.0f
  14 #endif
  15
  16 #ifndef DRIFT_THR_ASSIST_GAIN
  17  # define DRIFT_THR_ASSIST_GAIN 0.0018f    // gain controlling amount of throttle assistance
  18 #endif
  19
  20 #ifndef DRIFT_THR_ASSIST_MAX
  21  # define DRIFT_THR_ASSIST_MAX  0.3f    // maximum assistance throttle assist will provide
  22 #endif
  23
  24 #ifndef DRIFT_THR_MIN
  25  # define DRIFT_THR_MIN         0.213f  // throttle assist will be active when pilot's throttle is above this value
  26 #endif
  27 #ifndef DRIFT_THR_MAX
  28  # define DRIFT_THR_MAX         0.787f  // throttle assist will be active when pilot's throttle is below this value
  29 #endif
  30
  31 // drift_init - initialise drift controller
  32 bool ModeDrift::init(bool ignore_checks)
  33 {
  34     return true;
  35 }
  36
  37 // drift_run - runs the drift controller
  38 // should be called at 100hz or more
  39 void ModeDrift::run()
  40 {
  41     static float braker = 0.0f;
  42     static float roll_input = 0.0f;
  43
  44     // convert pilot input to lean angles
  45     float target_roll, target_pitch;
  46     get_pilot_desired_lean_angles(target_roll, target_pitch, copter.aparm.angle_max, copter.aparm.angle_max);
  47
  48     // Grab inertial velocity
  49     const Vector3f& vel = inertial_nav.get_velocity_neu_cms();
  50
  51     // rotate roll, pitch input from north facing to vehicle's perspective
  52     float roll_vel =  vel.y * ahrs.cos_yaw() - vel.x * ahrs.sin_yaw(); // body roll vel
  53     float pitch_vel = vel.y * ahrs.sin_yaw() + vel.x * ahrs.cos_yaw(); // body pitch vel
  54
  55     // gain scheduling for yaw
  56     float pitch_vel2 = MIN(fabsf(pitch_vel), 2000);
  57     float target_yaw_rate = target_roll * (1.0f - (pitch_vel2 / 5000.0f)) * g2.command_model_acro_y.get_rate() / 45.0;
  58
  59     roll_vel = constrain_float(roll_vel, -DRIFT_SPEEDLIMIT, DRIFT_SPEEDLIMIT);
  60     pitch_vel = constrain_float(pitch_vel, -DRIFT_SPEEDLIMIT, DRIFT_SPEEDLIMIT);
  61
  62     roll_input = roll_input * .96f + (float)channel_yaw->get_control_in() * .04f;
  63
  64     // convert user input into desired roll velocity
  65     float roll_vel_error = roll_vel - (roll_input / DRIFT_SPEEDGAIN);
  66
  67     // roll velocity is feed into roll acceleration to minimize slip
  68     target_roll = roll_vel_error * -DRIFT_SPEEDGAIN;
  69     target_roll = constrain_float(target_roll, -4500.0f, 4500.0f);
  70
  71     // If we let go of sticks, bring us to a stop
  72     if (is_zero(target_pitch)) {
  73         // .14/ (.03 * 100) = 4.6 seconds till full braking
  74         braker += .03f;
  75         braker = MIN(braker, DRIFT_SPEEDGAIN);
  76         target_pitch = pitch_vel * braker;
  77     } else {
  78         braker = 0.0f;
  79     }
  80
  81     if (!motors->armed()) {
  82         // Motors should be Stopped
  83         motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::SHUT_DOWN);
  84     } else if (copter.ap.throttle_zero) {
  85         // Attempting to Land
  86         motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
  87     } else {
  88         motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::THROTTLE_UNLIMITED);
  89     }
  90
  91     switch (motors->get_spool_state()) {
  92     case AP_Motors::SpoolState::SHUT_DOWN:
  93         // Motors Stopped
  94         attitude_control->reset_yaw_target_and_rate(false);
  95         attitude_control->reset_rate_controller_I_terms();
  96         break;
  97
  98     case AP_Motors::SpoolState::GROUND_IDLE:
  99         // Landed
 100         attitude_control->reset_yaw_target_and_rate();
 101         attitude_control->reset_rate_controller_I_terms_smoothly();
 102         break;
 103
 104     case AP_Motors::SpoolState::THROTTLE_UNLIMITED:
 105         // clear landing flag above zero throttle
 106         if (!motors->limit.throttle_lower) {
 107             set_land_complete(false);
 108         }
 109         break;
 110
 111     case AP_Motors::SpoolState::SPOOLING_UP:
 112     case AP_Motors::SpoolState::SPOOLING_DOWN:
 113         // do nothing
 114         break;
 115     }
 116
 117     // call attitude controller
 118     attitude_control->input_euler_angle_roll_pitch_euler_rate_yaw(target_roll, target_pitch, target_yaw_rate);
 119
 120     // output pilot's throttle with angle boost
 121     const float assisted_throttle = get_throttle_assist(vel.z, get_pilot_desired_throttle());
 122     attitude_control->set_throttle_out(assisted_throttle, true, g.throttle_filt);
 123 }
 124
 125 // get_throttle_assist - return throttle output (range 0 ~ 1) based on pilot input and z-axis velocity
 126 float ModeDrift::get_throttle_assist(float velz, float pilot_throttle_scaled)
 127 {
 128     // throttle assist - adjusts throttle to slow the vehicle's vertical velocity
 129     //      Only active when pilot's throttle is between 213 ~ 787
 130     //      Assistance is strongest when throttle is at mid, drops linearly to no assistance at 213 and 787
 131     float thr_assist = 0.0f;
 132     if (pilot_throttle_scaled > DRIFT_THR_MIN && pilot_throttle_scaled < DRIFT_THR_MAX) {
 133         // calculate throttle assist gain
 134         thr_assist = 1.2f - ((float)fabsf(pilot_throttle_scaled - 0.5f) / 0.24f);
 135         thr_assist = constrain_float(thr_assist, 0.0f, 1.0f) * -DRIFT_THR_ASSIST_GAIN * velz;
 136
 137         // ensure throttle assist never adjusts the throttle by more than 300 pwm
 138         thr_assist = constrain_float(thr_assist, -DRIFT_THR_ASSIST_MAX, DRIFT_THR_ASSIST_MAX);
 139     }
 140
 141     return constrain_float(pilot_throttle_scaled + thr_assist, 0.0f, 1.0f);
 142 }
 143 #endif