Rover: fix logging of desired lateral acceleration

APMrover2/Log.cpp

@@ -206,7 +206,7 @@ void Rover::Log_Write_Steering()
         time_us        : AP_HAL::micros64(),
         steering_in        : channel_steer->get_control_in(),
         steering_out       : g2.motors.get_steering(),
-        desired_lat_accel  : g2.attitude_control.get_desired_lat_accel(),
+        desired_lat_accel  : control_mode->get_desired_lat_accel(),
         lat_accel          : lat_accel,
         desired_turn_rate  : degrees(g2.attitude_control.get_desired_turn_rate()),
         turn_rate          : degrees(ahrs.get_yaw_rate_earth())

APMrover2/mode.cpp

@@ -186,6 +186,15 @@ float Mode::crosstrack_error() const
     return g2.wp_nav.crosstrack_error();
 }
 
+// return desired lateral acceleration
+float Mode::get_desired_lat_accel() const
+{
+    if (!is_autopilot_mode()) {
+        return 0.0f;
+    }
+    return g2.wp_nav.get_lat_accel();
+}
+
 // set desired location
 void Mode::set_desired_location(const struct Location& destination, float next_leg_bearing_cd)
 {

APMrover2/mode.h

@@ -92,6 +92,7 @@ public:
     virtual float wp_bearing() const;
     virtual float nav_bearing() const;
     virtual float crosstrack_error() const;
+    virtual float get_desired_lat_accel() const;
 
     // get speed error in m/s, not currently supported
     float speed_error() const { return 0.0f; }
@@ -554,6 +555,13 @@ public:
     // steering requires velocity but not position
     bool requires_position() const override { return false; }
     bool requires_velocity() const override { return true; }
+
+    // return desired lateral acceleration
+    float get_desired_lat_accel() const override { return _desired_lat_accel; }
+
+private:
+
+    float _desired_lat_accel;   // desired lateral acceleration calculated from pilot steering input
 };
 
 class ModeInitializing : public Mode

APMrover2/mode_steering.cpp

@@ -9,6 +9,7 @@ void ModeSteering::update()
         // no valid speed so stop
         g2.motors.set_throttle(0.0f);
         g2.motors.set_steering(0.0f);
+        _desired_lat_accel = 0.0f;
         return;
     }
 
@@ -22,6 +23,7 @@ void ModeSteering::update()
         // pivot turning using turn rate controller
         // convert pilot steering input to desired turn rate in radians/sec
         const float target_turn_rate = (desired_steering / 4500.0f) * radians(g2.acro_turn_rate);
+        _desired_lat_accel = 0.0f;
 
         // run steering turn rate controller and throttle controller
         const float steering_out = attitude_control.get_steering_out_rate(target_turn_rate,
@@ -37,15 +39,15 @@ void ModeSteering::update()
         max_g_force = constrain_float(max_g_force, 0.1f, g.turn_max_g * GRAVITY_MSS);
 
         // convert pilot steering input to desired lateral acceleration
-        float desired_lat_accel = max_g_force * (desired_steering / 4500.0f);
+        _desired_lat_accel = max_g_force * (desired_steering / 4500.0f);
 
         // reverse target lateral acceleration if backing up
         if (reversed) {
-            desired_lat_accel = -desired_lat_accel;
+            _desired_lat_accel = -_desired_lat_accel;
         }
 
         // run lateral acceleration to steering controller
-        calc_steering_from_lateral_acceleration(desired_lat_accel, reversed);
+        calc_steering_from_lateral_acceleration(_desired_lat_accel, reversed);
     }
 
     // run speed to throttle controller