Blimp: remove vestiges of AHRS trim-from-rc-sticks functionality

This was definitely not working (no caller to auto_trim()), and has probably subtly broken in several other ways since it has not been autotested.

If this feature is wanted in the future then factoring Copter's support up into RC_Channel (and possible AP_Vehicle) is probably the way to do this.

we're moving towards using an RC aux switch for this functionality.

Blimp doesn't currently have suport for this functionality (lacking a call

Blimp/Blimp.h

@@ -239,10 +239,6 @@ class Blimp : public AP_Vehicle
     // arm_time_ms - Records when vehicle was armed. Will be Zero if we are disarmed.
     uint32_t arm_time_ms;
 
-    // Used to exit the roll and pitch auto trim function
-    uint8_t auto_trim_counter;
-    bool auto_trim_started = false;
-
     // last valid RC input time
     uint32_t last_radio_update_ms;
 
@@ -412,11 +408,6 @@ class Blimp : public AP_Vehicle
     bool rangefinder_alt_ok();
     bool rangefinder_up_ok();
 
-    // RC_Channel.cpp
-    void save_trim();
-    void auto_trim();
-    void auto_trim_cancel();
-
     // system.cpp
     void init_ardupilot() override;
     void startup_INS_ground();

Blimp/RC_Channel_Blimp.cpp

@@ -106,14 +106,6 @@ bool RC_Channel_Blimp::do_aux_function(const AuxFuncTrigger &trigger)
 
     switch (ch_option) {
 
-    case AUX_FUNC::SAVE_TRIM:
-        if ((ch_flag == AuxSwitchPos::HIGH) &&
-            (blimp.control_mode <= Mode::Number::MANUAL) &&
-            (blimp.channel_up->get_control_in() == 0)) {
-            blimp.save_trim();
-        }
-        break;
-
     case AUX_FUNC::LOITER:
         do_aux_function_change_mode(Mode::Number::LOITER, ch_flag);
         break;
@@ -127,69 +119,3 @@ bool RC_Channel_Blimp::do_aux_function(const AuxFuncTrigger &trigger)
     }
     return true;
 }
-
-// save_trim - adds roll and pitch trims from the radio to ahrs
-void Blimp::save_trim()
-{
-    // save roll and pitch trim
-    float roll_trim = ToRad((float)channel_right->get_control_in()*0.01f);
-    float pitch_trim = ToRad((float)channel_front->get_control_in()*0.01f);
-    ahrs.add_trim(roll_trim, pitch_trim);
-    LOGGER_WRITE_EVENT(LogEvent::SAVE_TRIM);
-    gcs().send_text(MAV_SEVERITY_INFO, "Trim saved");
-}
-
-// auto_trim - slightly adjusts the ahrs.roll_trim and ahrs.pitch_trim towards the current stick positions
-// meant to be called continuously while the pilot attempts to keep the blimp level
-void Blimp::auto_trim_cancel()
-{
-    auto_trim_counter = 0;
-    AP_Notify::flags.save_trim = false;
-    gcs().send_text(MAV_SEVERITY_INFO, "AutoTrim cancelled");
-}
-
-void Blimp::auto_trim()
-{
-    if (auto_trim_counter > 0) {
-        if (blimp.flightmode != &blimp.mode_manual ||
-            !blimp.motors->armed()) {
-            auto_trim_cancel();
-            return;
-        }
-
-        // flash the leds
-        AP_Notify::flags.save_trim = true;
-
-        if (!auto_trim_started) {
-            if (ap.land_complete) {
-                // haven't taken off yet
-                return;
-            }
-            auto_trim_started = true;
-        }
-
-        if (ap.land_complete) {
-            // landed again.
-            auto_trim_cancel();
-            return;
-        }
-
-        auto_trim_counter--;
-
-        // calculate roll trim adjustment
-        float roll_trim_adjustment = ToRad((float)channel_right->get_control_in() / 4000.0f);
-
-        // calculate pitch trim adjustment
-        float pitch_trim_adjustment = ToRad((float)channel_front->get_control_in() / 4000.0f);
-
-        // add trim to ahrs object
-        // save to eeprom on last iteration
-        ahrs.add_trim(roll_trim_adjustment, pitch_trim_adjustment, (auto_trim_counter == 0));
-
-        // on last iteration restore leds and accel gains to normal
-        if (auto_trim_counter == 0) {
-            AP_Notify::flags.save_trim = false;
-            gcs().send_text(MAV_SEVERITY_INFO, "AutoTrim: Trims saved");
-        }
-    }
-}

Blimp/motors.cpp

@@ -2,7 +2,6 @@
 
 #define ARM_DELAY               20  // called at 10hz so 2 seconds
 #define DISARM_DELAY            20  // called at 10hz so 2 seconds
-#define AUTO_TRIM_DELAY         100 // called at 10hz so 10 seconds
 #define LOST_VEHICLE_DELAY      10  // called at 10hz so 1 second
 
 // arm_motors_check - checks for pilot input to arm or disarm the blimp
@@ -29,7 +28,7 @@ void Blimp::arm_motors_check()
     if (yaw_in > 900) {
 
         // increase the arming counter to a maximum of 1 beyond the auto trim counter
-        if (arming_counter <= AUTO_TRIM_DELAY) {
+        if (arming_counter < ARM_DELAY) {
             arming_counter++;
         }
 
@@ -41,13 +40,6 @@ void Blimp::arm_motors_check()
             }
         }
 
-        // arm the motors and configure for flight
-        if (arming_counter == AUTO_TRIM_DELAY && motors->armed() && control_mode == Mode::Number::MANUAL) {
-            gcs().send_text(MAV_SEVERITY_INFO, "AutoTrim start");
-            auto_trim_counter = 250;
-            auto_trim_started = false;
-        }
-
         // full left and rudder disarming is enabled
     } else if ((yaw_in < -900) && (arming_rudder == AP_Arming::RudderArming::ARMDISARM)) {
         if (!flightmode->has_manual_throttle() && !ap.land_complete) {