Rover: re-order acro mode to add early return

non-functional change

APMrover2/mode_acro.cpp

@@ -3,12 +3,6 @@
 
 void ModeAcro::update()
 {
-    float desired_steering, desired_throttle;
-    get_pilot_desired_steering_and_throttle(desired_steering, desired_throttle);
-
-    // convert pilot throttle input to desired speed (up to twice the cruise speed)
-    float target_speed = desired_throttle * 0.01f * calc_speed_max(g.speed_cruise, g.throttle_cruise * 0.01f);
-
     // get speed forward
     float speed;
     if (!attitude_control.get_forward_speed(speed)) {
@@ -18,23 +12,31 @@ void ModeAcro::update()
         return;
     }
 
+    // convert pilot stick input into desired steering and throttle
+    float desired_steering, desired_throttle;
+    get_pilot_desired_steering_and_throttle(desired_steering, desired_throttle);
+
+    // convert pilot throttle input to desired speed (up to twice the cruise speed)
+    float target_speed = desired_throttle * 0.01f * calc_speed_max(g.speed_cruise, g.throttle_cruise * 0.01f);
+
+    // convert pilot steering input to desired turn rate in radians/sec
+    float target_turn_rate = (desired_steering / 4500.0f) * radians(g2.acro_turn_rate);
+
     // determine if pilot is requesting pivot turn
     bool is_pivot_turning = g2.motors.have_skid_steering() && is_zero(target_speed) && (!is_zero(desired_steering));
 
-    // convert steering request to turn rate in radians/sec
+    // stop vehicle if target speed is zero and not pivot turning
-    float turn_rate = (desired_steering / 4500.0f) * radians(g2.acro_turn_rate);
+    if (is_zero(target_speed) && !is_pivot_turning) {
+        stop_vehicle();
+        return;
+    }
 
     // set reverse flag backing up
     bool reversed = is_negative(target_speed);
     rover.set_reverse(reversed);
 
-    // run speed to throttle output controller
+    // run steering turn rate controller and throttle controller
-    if (is_zero(target_speed) && !is_pivot_turning) {
+    float steering_out = attitude_control.get_steering_out_rate(target_turn_rate, g2.motors.have_skid_steering(), g2.motors.limit.steer_left, g2.motors.limit.steer_right, reversed);
-        stop_vehicle();
+    g2.motors.set_steering(steering_out * 4500.0f);
-    } else {
+    calc_throttle(target_speed, false);
-        // run steering turn rate controller and throttle controller
-        float steering_out = attitude_control.get_steering_out_rate(turn_rate, g2.motors.have_skid_steering(), g2.motors.limit.steer_left, g2.motors.limit.steer_right, reversed);
-        g2.motors.set_steering(steering_out * 4500.0f);
-        calc_throttle(target_speed, false);
-    }
 }