Copter: Fix before squash

ArduCopter/land_detector.cpp

@@ -186,7 +186,7 @@ void Copter::update_throttle_mix()
         // check for large acceleration - falling or high turbulence
         const bool accel_moving = (land_accel_ef_filter.get().length() > LAND_CHECK_ACCEL_MOVING);
 
-        // check for requested decent
+        // check for requested descent
         bool descent_not_demanded = pos_control->get_vel_desired_cms().z >= 0.0f;
 
         // check if landing

ArduCopter/mode.cpp

@@ -468,7 +468,7 @@ void Mode::make_safe_spool_down()
         break;
     }
 
-    pos_control->relax_z_controller(0.0f);   // forces throttle output to go to zero
+    pos_control->relax_z_controller(0.0f);   // forces throttle output to decay to zero
     pos_control->update_z_controller();
     // we may need to move this out
     attitude_control->input_euler_angle_roll_pitch_euler_rate_yaw(0.0f, 0.0f, 0.0f);
@@ -622,7 +622,7 @@ void Mode::land_run_horizontal_control()
             thrust_vector.y *= ratio;
 
             // tell position controller we are applying an external limit
-            pos_control->set_limit_xy();
+            pos_control->set_externally_limited_xy();
         }
     }
 
@@ -801,7 +801,7 @@ GCS_Copter &Mode::gcs()
 // are taking off so I terms can be cleared
 void Mode::set_throttle_takeoff()
 {
-    // tell position controller to reset alt target and reset I terms
+    // initialise the vertical position controller
     pos_control->init_z_controller();
 }
 

ArduCopter/mode.h

@@ -164,7 +164,7 @@ protected:
     private:
         bool _running;
         float take_off_start_alt;
-        float take_off_alt;
+        float take_off_complete_alt ;
     };
 
     static _TakeOff takeoff;

ArduCopter/mode_althold.cpp

@@ -8,7 +8,7 @@
 // althold_init - initialise althold controller
 bool ModeAltHold::init(bool ignore_checks)
 {
-    // initialise position and desired velocity
+    // initialise the vertical position controller
     if (!pos_control->is_active_z()) {
         pos_control->init_z_controller();
     }
@@ -20,7 +20,7 @@ bool ModeAltHold::init(bool ignore_checks)
 // should be called at 100hz or more
 void ModeAltHold::run()
 {
-    // initialize vertical speeds and acceleration
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(-get_pilot_speed_dn(), g.pilot_speed_up, g.pilot_accel_z);
 
     // apply SIMPLE mode transform to pilot inputs
@@ -46,7 +46,7 @@ void ModeAltHold::run()
     case AltHold_MotorStopped:
         attitude_control->reset_rate_controller_I_terms();
         attitude_control->set_yaw_target_to_current_heading();
-        pos_control->relax_z_controller(0.0f);   // forces throttle output to go to zero
+        pos_control->relax_z_controller(0.0f);   // forces throttle output to decay to zero
         break;
 
     case AltHold_Landed_Ground_Idle:
@@ -55,7 +55,7 @@ void ModeAltHold::run()
 
     case AltHold_Landed_Pre_Takeoff:
         attitude_control->reset_rate_controller_I_terms_smoothly();
-        pos_control->relax_z_controller(0.0f);   // forces throttle output to go to zero
+        pos_control->relax_z_controller(0.0f);   // forces throttle output to decay to zero
         break;
 
     case AltHold_Takeoff:
@@ -67,7 +67,7 @@ void ModeAltHold::run()
         // get avoidance adjusted climb rate
         target_climb_rate = get_avoidance_adjusted_climbrate(target_climb_rate);
 
-        // get take-off adjusted pilot and takeoff climb rates
+        // set position controller targets adjusted for pilot input
         takeoff.do_pilot_takeoff(target_climb_rate);
         break;
 
@@ -92,6 +92,6 @@ void ModeAltHold::run()
     // call attitude controller
     attitude_control->input_euler_angle_roll_pitch_euler_rate_yaw(target_roll, target_pitch, target_yaw_rate);
 
-    // call z-axis position controller
+    // run the vertical position controller and set output throttle
     pos_control->update_z_controller();
 }

ArduCopter/mode_auto.cpp

@@ -270,7 +270,7 @@ void ModeAuto::land_start(const Vector3f& destination)
     // initialise loiter target destination
     loiter_nav->init_target(destination);
 
-    // initialise position and desired velocity
+    // initialise the vertical position controller
     if (!pos_control->is_active_z()) {
         pos_control->init_z_controller();
     }
@@ -825,7 +825,8 @@ void ModeAuto::wp_run()
     // run waypoint controller
     copter.failsafe_terrain_set_status(wp_nav->update_wpnav());
 
-    // call z-axis position controller (wpnav should have already updated it's alt target)
+    // WP_Nav has set the vertical position control targets
+    // run the vertical position controller and set output throttle
     pos_control->update_z_controller();
 
     // call attitude controller
@@ -883,7 +884,8 @@ void ModeAuto::circle_run()
     // call circle controller
     copter.failsafe_terrain_set_status(copter.circle_nav->update());
 
-    // call z-axis position controller
+    // WP_Nav has set the vertical position control targets
+    // run the vertical position controller and set output throttle
     pos_control->update_z_controller();
 
     if (auto_yaw.mode() == AUTO_YAW_HOLD) {
@@ -994,7 +996,7 @@ void ModeAuto::payload_place_start(const Vector3f& destination)
     // initialise loiter target destination
     loiter_nav->init_target(destination);
 
-    // initialise position and desired velocity
+    // initialise the vertical position controller
     pos_control->init_z_controller();
 
     // initialise yaw
@@ -1326,6 +1328,7 @@ void ModeAuto::do_loiter_to_alt(const AP_Mission::Mission_Command& cmd)
     loiter_to_alt.reached_alt = false;
     loiter_to_alt.alt_error_cm = 0;
 
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(wp_nav->get_default_speed_down(), wp_nav->get_default_speed_up(), wp_nav->get_accel_z());
 }
 

ArduCopter/mode_autorotate.cpp

@@ -231,13 +231,13 @@ void ModeAutorotate::run()
                 float pilot_des_v_z = get_pilot_desired_climb_rate(channel_throttle->get_control_in());
                 pilot_des_v_z = constrain_float(pilot_des_v_z, pilot_spd_dn, pilot_spd_up);
 
-                // Calculate target climb rate adjustment to transition from bail out decent speed to requested climb rate on stick.
+                // Calculate target climb rate adjustment to transition from bail out descent speed to requested climb rate on stick.
                 _target_climb_rate_adjust = (curr_vel_z - pilot_des_v_z)/(_bail_time - BAILOUT_MOTOR_RAMP_TIME); //accounting for 0.5s motor spool time
 
                 // Calculate pitch target adjustment rate to return to level
                 _target_pitch_adjust = _pitch_target/_bail_time;
 
-                // Set speed and acceleration limit
+                // set vertical speed and acceleration limits
                 pos_control->set_max_speed_accel_z(curr_vel_z, pilot_spd_up, fabsf(_target_climb_rate_adjust));
 
                 motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::THROTTLE_UNLIMITED);

ArduCopter/mode_autotune.cpp

@@ -93,6 +93,7 @@ void AutoTune::get_pilot_desired_rp_yrate_cd(float &des_roll_cd, float &des_pitc
  */
 void AutoTune::init_z_limits()
 {
+    // set vertical speed and acceleration limits
     copter.pos_control->set_max_speed_accel_z(-copter.get_pilot_speed_dn(), copter.g.pilot_speed_up, copter.g.pilot_accel_z);
 }
 

ArduCopter/mode_brake.cpp

@@ -15,10 +15,10 @@ bool ModeBrake::init(bool ignore_checks)
     // initialise position controller
     pos_control->init_xy_controller();
 
-    // initialize vertical speed and acceleration
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(BRAKE_MODE_SPEED_Z, BRAKE_MODE_SPEED_Z, BRAKE_MODE_DECEL_RATE);
 
-    // initialise position and desired velocity
+    // initialise the vertical position controller
     if (!pos_control->is_active_z()) {
         pos_control->init_z_controller();
     }

ArduCopter/mode_circle.cpp

@@ -12,7 +12,7 @@ bool ModeCircle::init(bool ignore_checks)
     pilot_yaw_override = false;
     speed_changing = false;
 
-    // initialize speeds and accelerations
+    // set speed and acceleration limits
     pos_control->set_max_speed_accel_xy(wp_nav->get_default_speed_xy(), wp_nav->get_wp_acceleration());
     pos_control->set_max_speed_accel_z(-get_pilot_speed_dn(), g.pilot_speed_up, g.pilot_accel_z);
 
@@ -26,7 +26,7 @@ bool ModeCircle::init(bool ignore_checks)
 // should be called at 100hz or more
 void ModeCircle::run()
 {
-    // initialize speeds and accelerations
+    // set speed and acceleration limits
     pos_control->set_max_speed_accel_xy(wp_nav->get_default_speed_xy(), wp_nav->get_wp_acceleration());
     pos_control->set_max_speed_accel_z(-get_pilot_speed_dn(), g.pilot_speed_up, g.pilot_accel_z);
 

ArduCopter/mode_flowhold.cpp

@@ -88,10 +88,10 @@ bool ModeFlowHold::init(bool ignore_checks)
         return false;
     }
 
-    // initialize vertical maximum speeds and acceleration
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(-get_pilot_speed_dn(), g.pilot_speed_up, g.pilot_accel_z);
 
-    // initialise position and desired velocity
+    // initialise the vertical position controller
     if (!copter.pos_control->is_active_z()) {
         pos_control->init_z_controller();
     }
@@ -229,7 +229,7 @@ void ModeFlowHold::run()
 {
     update_height_estimate();
 
-    // initialize vertical speeds and acceleration
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(-get_pilot_speed_dn(), g.pilot_speed_up, g.pilot_accel_z);
 
     // apply SIMPLE mode transform to pilot inputs
@@ -264,7 +264,7 @@ void ModeFlowHold::run()
         copter.motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::SHUT_DOWN);
         copter.attitude_control->reset_rate_controller_I_terms();
         copter.attitude_control->set_yaw_target_to_current_heading();
-        copter.pos_control->relax_z_controller(0.0f);   // forces throttle output to go to zero
+        copter.pos_control->relax_z_controller(0.0f);   // forces throttle output to decay to zero
         flow_pi_xy.reset_I();
         break;
 
@@ -280,7 +280,7 @@ void ModeFlowHold::run()
         // get avoidance adjusted climb rate
         target_climb_rate = get_avoidance_adjusted_climbrate(target_climb_rate);
 
-        // get take-off adjusted pilot and takeoff climb rates
+        // set position controller targets adjusted for pilot input
         takeoff.do_pilot_takeoff(target_climb_rate);
         break;
 
@@ -290,7 +290,7 @@ void ModeFlowHold::run()
 
     case AltHold_Landed_Pre_Takeoff:
         attitude_control->reset_rate_controller_I_terms_smoothly();
-        pos_control->relax_z_controller(0.0f);   // forces throttle output to go to zero
+        pos_control->relax_z_controller(0.0f);   // forces throttle output to decay to zero
         break;
 
     case AltHold_Flying:
@@ -336,7 +336,7 @@ void ModeFlowHold::run()
     // call attitude controller
     copter.attitude_control->input_euler_angle_roll_pitch_euler_rate_yaw(bf_angles.x, bf_angles.y, target_yaw_rate);
 
-    // call z-axis position controller
+    // run the vertical position controller and set output throttle
     pos_control->update_z_controller();
 }
 

ArduCopter/mode_guided.cpp

@@ -164,10 +164,10 @@ void ModeGuided::vel_control_start()
     // initialise horizontal speed, acceleration
     pos_control->set_max_speed_accel_xy(wp_nav->get_default_speed_xy(), wp_nav->get_wp_acceleration());
 
-    // initialize vertical speeds and acceleration
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(wp_nav->get_default_speed_down(), wp_nav->get_default_speed_up(), wp_nav->get_accel_z());
 
-    // initialise velocity controller
+    // initialise the position controller
     pos_control->init_z_controller();
     pos_control->init_xy_controller();
 }
@@ -181,10 +181,10 @@ void ModeGuided::posvel_control_start()
     // initialise horizontal speed, acceleration
     pos_control->set_max_speed_accel_xy(wp_nav->get_default_speed_xy(), wp_nav->get_wp_acceleration());
 
-    // initialize vertical speeds and acceleration
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(wp_nav->get_default_speed_down(), wp_nav->get_default_speed_up(), wp_nav->get_accel_z());
 
-    // initialise velocity controller
+    // initialise the position controller
     pos_control->init_z_controller();
     pos_control->init_xy_controller();
 
@@ -203,10 +203,10 @@ void ModeGuided::angle_control_start()
     // set guided_mode to velocity controller
     guided_mode = SubMode::Angle;
 
-    // set vertical speed and acceleration
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(wp_nav->get_default_speed_down(), wp_nav->get_default_speed_up(), wp_nav->get_accel_z());
 
-    // initialise position and desired velocity
+    // initialise the vertical position controller
     if (!pos_control->is_active_z()) {
         pos_control->init_z_controller();
     }
@@ -439,7 +439,8 @@ void ModeGuided::pos_control_run()
     // run waypoint controller
     copter.failsafe_terrain_set_status(wp_nav->update_wpnav());
 
-    // call z-axis position controller (wpnav should have already updated it's alt target)
+    // WP_Nav has set the vertical position control targets
+    // run the vertical position controller and set output throttle
     pos_control->update_z_controller();
 
     // call attitude controller
@@ -552,11 +553,8 @@ void ModeGuided::posvel_control_run()
         }
     }
 
-    // calculate dt
-    float dt = pos_control->get_dt();
-
     // advance position target using velocity target
-    guided_pos_target_cm += guided_vel_target_cms * dt;
+    guided_pos_target_cm += guided_vel_target_cms * pos_control->get_dt();
 
     // send position and velocity targets to position controller
     pos_control->input_pos_vel_accel_xy(guided_pos_target_cm, guided_vel_target_cms, Vector3f());

ArduCopter/mode_land.cpp

@@ -12,10 +12,10 @@ bool ModeLand::init(bool ignore_checks)
         loiter_nav->init_target(stopping_point);
     }
 
-    // initialize vertical maximum speeds and acceleration
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(wp_nav->get_default_speed_down(), wp_nav->get_default_speed_up(), wp_nav->get_accel_z());
 
-    // initialise position and desired velocity
+    // initialise the vertical position controller
     if (!pos_control->is_active_z()) {
         pos_control->init_z_controller();
     }

ArduCopter/mode_loiter.cpp

@@ -25,7 +25,7 @@ bool ModeLoiter::init(bool ignore_checks)
     }
     loiter_nav->init_target();
 
-    // initialise position and desired velocity
+    // initialise the vertical position controller
     if (!pos_control->is_active_z()) {
         pos_control->init_z_controller();
     }
@@ -77,7 +77,7 @@ void ModeLoiter::run()
     float target_yaw_rate = 0.0f;
     float target_climb_rate = 0.0f;
 
-    // initialize vertical speed and acceleration
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(-get_pilot_speed_dn(), g.pilot_speed_up, g.pilot_accel_z);
 
     // process pilot inputs unless we are in radio failsafe
@@ -116,7 +116,7 @@ void ModeLoiter::run()
     case AltHold_MotorStopped:
         attitude_control->reset_rate_controller_I_terms();
         attitude_control->set_yaw_target_to_current_heading();
-        pos_control->relax_z_controller(0.0f);   // forces throttle output to go to zero
+        pos_control->relax_z_controller(0.0f);   // forces throttle output to decay to zero
         loiter_nav->init_target();
         attitude_control->input_thrust_vector_rate_heading(loiter_nav->get_thrust_vector(), target_yaw_rate);
         break;
@@ -130,7 +130,7 @@ void ModeLoiter::run()
         // get avoidance adjusted climb rate
         target_climb_rate = get_avoidance_adjusted_climbrate(target_climb_rate);
 
-        // get take-off adjusted pilot and takeoff climb rates
+        // set position controller targets adjusted for pilot input
         takeoff.do_pilot_takeoff(target_climb_rate);
 
         // run loiter controller
@@ -148,7 +148,7 @@ void ModeLoiter::run()
         attitude_control->reset_rate_controller_I_terms_smoothly();
         loiter_nav->init_target();
         attitude_control->input_euler_angle_roll_pitch_euler_rate_yaw(0.0f, 0.0f, 0.0f);
-        pos_control->relax_z_controller(0.0f);   // forces throttle output to go to zero
+        pos_control->relax_z_controller(0.0f);   // forces throttle output to decay to zero
         break;
 
     case AltHold_Flying:
@@ -177,7 +177,7 @@ void ModeLoiter::run()
         break;
     }
 
-    // call z-axis position controller
+    // run the vertical position controller and set output throttle
     pos_control->update_z_controller();
 }
 

ArduCopter/mode_poshold.cpp

@@ -27,10 +27,10 @@
 // poshold_init - initialise PosHold controller
 bool ModePosHold::init(bool ignore_checks)
 {
-    // initialize vertical speeds and acceleration
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(-get_pilot_speed_dn(), g.pilot_speed_up, g.pilot_accel_z);
 
-    // initialise position and desired velocity
+    // initialise the vertical position controller
     if (!pos_control->is_active_z()) {
         pos_control->init_z_controller();
     }
@@ -70,7 +70,7 @@ void ModePosHold::run()
     float controller_to_pilot_pitch_mix;    // mix of controller and pilot controls.  0 = fully last controller controls, 1 = fully pilot controls
     const Vector3f& vel = inertial_nav.get_velocity();
 
-    // initialize vertical speeds and acceleration
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(-get_pilot_speed_dn(), g.pilot_speed_up, g.pilot_accel_z);
     loiter_nav->clear_pilot_desired_acceleration();
 
@@ -102,7 +102,7 @@ void ModePosHold::run()
     case AltHold_MotorStopped:
         attitude_control->reset_rate_controller_I_terms();
         attitude_control->set_yaw_target_to_current_heading();
-        pos_control->relax_z_controller(0.0f);   // forces throttle output to go to zero
+        pos_control->relax_z_controller(0.0f);   // forces throttle output to decay to zero
         loiter_nav->clear_pilot_desired_acceleration();
         loiter_nav->init_target();
         loiter_nav->update(false);
@@ -124,7 +124,7 @@ void ModePosHold::run()
         // get avoidance adjusted climb rate
         target_climb_rate = get_avoidance_adjusted_climbrate(target_climb_rate);
 
-        // get take-off adjusted pilot and takeoff climb rates
+        // set position controller targets adjusted for pilot input
         takeoff.do_pilot_takeoff(target_climb_rate);
 
         // init and update loiter although pilot is controlling lean angles
@@ -147,7 +147,7 @@ void ModePosHold::run()
 
     case AltHold_Landed_Pre_Takeoff:
         attitude_control->reset_rate_controller_I_terms_smoothly();
-        pos_control->relax_z_controller(0.0f);   // forces throttle output to go to zero
+        pos_control->relax_z_controller(0.0f);   // forces throttle output to decay to zero
 
         // set poshold state to pilot override
         roll_mode = RPMode::PILOT_OVERRIDE;
@@ -490,7 +490,7 @@ void ModePosHold::run()
     // call attitude controller
     attitude_control->input_euler_angle_roll_pitch_euler_rate_yaw(roll, pitch, target_yaw_rate);
 
-    // call z-axis position controller
+    // run the vertical position controller and set output throttle
     pos_control->update_z_controller();
 }
 

ArduCopter/mode_rtl.cpp

@@ -171,7 +171,8 @@ void ModeRTL::climb_return_run()
     // run waypoint controller
     copter.failsafe_terrain_set_status(wp_nav->update_wpnav());
 
-    // call z-axis position controller (wpnav should have already updated it's alt target)
+    // WP_Nav has set the vertical position control targets
+    // run the vertical position controller and set output throttle
     pos_control->update_z_controller();
 
     // call attitude controller
@@ -228,7 +229,8 @@ void ModeRTL::loiterathome_run()
     // run waypoint controller
     copter.failsafe_terrain_set_status(wp_nav->update_wpnav());
 
-    // call z-axis position controller (wpnav should have already updated it's alt target)
+    // WP_Nav has set the vertical position control targets
+    // run the vertical position controller and set output throttle
     pos_control->update_z_controller();
 
     // call attitude controller
@@ -335,7 +337,8 @@ void ModeRTL::descent_run()
     // run loiter controller
     loiter_nav->update();
 
-    // call z-axis position controller
+    // WP_Nav has set the vertical position control targets
+    // run the vertical position controller and set output throttle
     pos_control->set_alt_target_with_slew(rtl_path.descent_target.alt);
     pos_control->update_z_controller();
 
@@ -355,7 +358,7 @@ void ModeRTL::land_start()
     // Set wp navigation target to above home
     loiter_nav->init_target(wp_nav->get_wp_destination());
 
-    // initialise position and desired velocity
+    // initialise the vertical position controller
     if (!pos_control->is_active_z()) {
         pos_control->init_z_controller();
     }

ArduCopter/mode_sport.cpp

@@ -9,10 +9,10 @@
 // sport_init - initialise sport controller
 bool ModeSport::init(bool ignore_checks)
 {
-    // initialize vertical speed and acceleration
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(-get_pilot_speed_dn(), g.pilot_speed_up, g.pilot_accel_z);
 
-    // initialise position and desired velocity
+    // initialise the vertical position controller
     if (!pos_control->is_active_z()) {
         pos_control->init_z_controller();
     }
@@ -24,7 +24,7 @@ bool ModeSport::init(bool ignore_checks)
 // should be called at 100hz or more
 void ModeSport::run()
 {
-    // initialize vertical speed and acceleration
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(-get_pilot_speed_dn(), g.pilot_speed_up, g.pilot_accel_z);
 
     // apply SIMPLE mode transform
@@ -76,7 +76,7 @@ void ModeSport::run()
     case AltHold_MotorStopped:
         attitude_control->reset_rate_controller_I_terms();
         attitude_control->set_yaw_target_to_current_heading();
-        pos_control->relax_z_controller(0.0f);   // forces throttle output to go to zero
+        pos_control->relax_z_controller(0.0f);   // forces throttle output to decay to zero
         break;
 
     case AltHold_Takeoff:
@@ -88,7 +88,7 @@ void ModeSport::run()
         // get avoidance adjusted climb rate
         target_climb_rate = get_avoidance_adjusted_climbrate(target_climb_rate);
 
-        // get take-off adjusted pilot and takeoff climb rates
+        // set position controller targets adjusted for pilot input
         takeoff.do_pilot_takeoff(target_climb_rate);
         break;
 
@@ -98,7 +98,7 @@ void ModeSport::run()
 
     case AltHold_Landed_Pre_Takeoff:
         attitude_control->reset_rate_controller_I_terms_smoothly();
-        pos_control->relax_z_controller(0.0f);   // forces throttle output to go to zero
+        pos_control->relax_z_controller(0.0f);   // forces throttle output to decay to zero
         break;
 
     case AltHold_Flying:
@@ -117,7 +117,7 @@ void ModeSport::run()
     // call attitude controller
     attitude_control->input_euler_rate_roll_pitch_yaw(target_roll_rate, target_pitch_rate, target_yaw_rate);
 
-    // call z-axis position controller
+    // run the vertical position controller and set output throttle
     pos_control->update_z_controller();
 }
 

ArduCopter/mode_throw.cpp

@@ -22,7 +22,7 @@ bool ModeThrow::init(bool ignore_checks)
     // initialise pos controller speed and acceleration
     pos_control->set_max_speed_accel_xy(wp_nav->get_default_speed_xy(), BRAKE_MODE_DECEL_RATE);
 
-    // initialize vertical speed and acceleration
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(BRAKE_MODE_SPEED_Z, BRAKE_MODE_SPEED_Z, BRAKE_MODE_DECEL_RATE);
 
     return true;

ArduCopter/mode_zigzag.cpp

@@ -83,7 +83,7 @@ bool ModeZigZag::init(bool ignore_checks)
     }
     loiter_nav->init_target();
 
-    // initialise position_z and desired velocity_z
+    // initialise the vertical position controller
     if (!pos_control->is_active_z()) {
         pos_control->init_z_controller();
     }
@@ -110,7 +110,7 @@ void ModeZigZag::exit()
 // should be called at 100hz or more
 void ModeZigZag::run()
 {
-    // initialize vertical speed and acceleration's range
+    // set vertical speed and acceleration limits
     pos_control->set_max_speed_accel_z(-get_pilot_speed_dn(), g.pilot_speed_up, g.pilot_accel_z);
 
     // set the direction and the total number of lines
@@ -269,7 +269,8 @@ void ModeZigZag::auto_control()
     // run waypoint controller
     const bool wpnav_ok = wp_nav->update_wpnav();
 
-    // call z-axis position controller (wp_nav should have already updated its alt target)
+    // WP_Nav has set the vertical position control targets
+    // run the vertical position controller and set output throttle
     pos_control->update_z_controller();
 
     // call attitude controller
@@ -326,7 +327,7 @@ void ModeZigZag::manual_control()
     case AltHold_MotorStopped:
         attitude_control->reset_rate_controller_I_terms();
         attitude_control->set_yaw_target_to_current_heading();
-        pos_control->relax_z_controller(0.0f);   // forces throttle output to go to zero
+        pos_control->relax_z_controller(0.0f);   // forces throttle output to decay to zero
         loiter_nav->init_target();
         attitude_control->input_euler_angle_roll_pitch_euler_rate_yaw(loiter_nav->get_roll(), loiter_nav->get_pitch(), target_yaw_rate);
         break;
@@ -346,7 +347,7 @@ void ModeZigZag::manual_control()
         // call attitude controller
         attitude_control->input_euler_angle_roll_pitch_euler_rate_yaw(loiter_nav->get_roll(), loiter_nav->get_pitch(), target_yaw_rate);
 
-        // get take-off adjusted pilot and takeoff climb rates
+        // set position controller targets adjusted for pilot input
         takeoff.do_pilot_takeoff(target_climb_rate);
         break;
 
@@ -358,7 +359,7 @@ void ModeZigZag::manual_control()
         attitude_control->reset_rate_controller_I_terms_smoothly();
         loiter_nav->init_target();
         attitude_control->input_euler_angle_roll_pitch_euler_rate_yaw(0.0f, 0.0f, 0.0f);
-        pos_control->relax_z_controller(0.0f);   // forces throttle output to go to zero
+        pos_control->relax_z_controller(0.0f);   // forces throttle output to decay to zero
         break;
 
     case AltHold_Flying:
@@ -381,7 +382,7 @@ void ModeZigZag::manual_control()
         break;
     }
 
-    // call z-axis position controller
+    // run the vertical position controller and set output throttle
     pos_control->update_z_controller();
 }
 

ArduCopter/takeoff.cpp

@@ -48,7 +48,7 @@ bool Mode::do_user_takeoff(float takeoff_alt_cm, bool must_navigate)
     return true;
 }
 
-// start takeoff to specified altitude above home in centimetres
+// start takeoff to specified altitude above home in centimeters
 void Mode::_TakeOff::start(float alt_cm)
 {
     // indicate we are taking off
@@ -59,7 +59,7 @@ void Mode::_TakeOff::start(float alt_cm)
     // initialise takeoff state
     _running = true;
     take_off_start_alt = copter.pos_control->get_pos_target_z_cm();
-    take_off_alt = take_off_start_alt + alt_cm;
+    take_off_complete_alt  = take_off_start_alt + alt_cm;
 }
 
 // stop takeoff
@@ -68,7 +68,8 @@ void Mode::_TakeOff::stop()
     _running = false;
 }
 
-// do_pilot_takeoff - commands the aircraft to the take off altitude
+// do_pilot_takeoff - controls the vertical position controller during the process of taking off
+//  take off is complete when the vertical target reaches the take off altitude.
 //  climb is cancelled if pilot_climb_rate_cm becomes negative
 //  sets take off to complete when target altitude is within 1% of the take off altitude
 void Mode::_TakeOff::do_pilot_takeoff(float& pilot_climb_rate_cm)
@@ -82,7 +83,7 @@ void Mode::_TakeOff::do_pilot_takeoff(float& pilot_climb_rate_cm)
     Vector3f vel;
     Vector3f accel;
 
-    pos.z = take_off_alt;
+    pos.z = take_off_complete_alt ;
     vel.z = pilot_climb_rate_cm;
 
     // command the aircraft to the take off altitude and current pilot climb rate
@@ -90,7 +91,7 @@ void Mode::_TakeOff::do_pilot_takeoff(float& pilot_climb_rate_cm)
 
     // stop take off early and return if negative climb rate is commanded or we are within 0.1% of our take off altitude
     if (is_negative(pilot_climb_rate_cm) ||
-        (take_off_alt - take_off_start_alt) * 0.999f < copter.pos_control->get_pos_target_z_cm() - take_off_start_alt) {
+        (take_off_complete_alt  - take_off_start_alt) * 0.999f < copter.pos_control->get_pos_target_z_cm() - take_off_start_alt) {
         stop();
     }
 }
@@ -120,7 +121,7 @@ void Mode::auto_takeoff_run()
     } else {
         // motors have not completed spool up yet so relax navigation and position controllers
         wp_nav->shift_wp_origin_and_destination_to_current_pos_xy();
-        pos_control->relax_z_controller(0.0f);   // forces throttle output to go to zero
+        pos_control->relax_z_controller(0.0f);   // forces throttle output to decay to zero
         pos_control->update_z_controller();
         attitude_control->set_yaw_target_to_current_heading();
         attitude_control->reset_rate_controller_I_terms();
@@ -139,7 +140,7 @@ void Mode::auto_takeoff_run()
             wp_nav->shift_wp_origin_and_destination_to_current_pos_xy();
         }
         // tell the position controller that we have limited roll/pitch demand to prevent integrator buildup
-        pos_control->set_limit_xy();
+        pos_control->set_externally_limited_xy();
     }
 
     // run waypoint controller
@@ -150,7 +151,8 @@ void Mode::auto_takeoff_run()
         thrustvector = wp_nav->get_thrust_vector();
     }
 
-    // call z-axis position controller (wpnav should have already updated it's alt target)
+    // WP_Nav has set the vertical position control targets
+    // run the vertical position controller and set output throttle
     copter.pos_control->update_z_controller();
 
     // roll & pitch from waypoint controller, yaw rate from pilot