manual_control_setpoint: change stick axes naming

In review it was requested to have a different name for
manual_control_setpoint.z because of the adjusted range.

I started to investigate what naming is most intuitive and found
that most people recognize the stick axes as roll, pitch, yaw, throttle.
It comes at no surprise because other autopilots
and APIs seem to share this convention.

While changing the code I realized that even within the code base
the axes are usually assigned to a variable with that name or
have comments next to the assignment clarifying the axes
using these names.

src/modules/mc_att_control/mc_att_control.hpp

@@ -118,8 +118,8 @@ private:
 	float _man_yaw_sp{0.f};                 /**< current yaw setpoint in manual mode */
 	float _man_tilt_max;                    /**< maximum tilt allowed for manual flight [rad] */
 
-	AlphaFilter<float> _man_x_input_filter;
-	AlphaFilter<float> _man_y_input_filter;
+	AlphaFilter<float> _man_roll_input_filter;
+	AlphaFilter<float> _man_pitch_input_filter;
 
 	hrt_abstime _last_run{0};
 	hrt_abstime _last_attitude_setpoint{0};

src/modules/mc_att_control/mc_att_control_main.cpp

@@ -116,11 +116,11 @@ MulticopterAttitudeControl::generate_attitude_setpoint(const Quatf &q, float dt,
 	if (reset_yaw_sp) {
 		_man_yaw_sp = yaw;
 
-	} else if ((_manual_control_setpoint.z > -.9f)
+	} else if ((_manual_control_setpoint.throttle > -.9f)
 		   || (_param_mc_airmode.get() == 2)) {
 
 		const float yaw_rate = math::radians(_param_mpc_man_y_max.get());
-		attitude_setpoint.yaw_sp_move_rate = _manual_control_setpoint.r * yaw_rate;
+		attitude_setpoint.yaw_sp_move_rate = _manual_control_setpoint.yaw * yaw_rate;
 		_man_yaw_sp = wrap_pi(_man_yaw_sp + attitude_setpoint.yaw_sp_move_rate * dt);
 	}
 
@@ -128,21 +128,18 @@ MulticopterAttitudeControl::generate_attitude_setpoint(const Quatf &q, float dt,
 	 * Input mapping for roll & pitch setpoints
 	 * ----------------------------------------
 	 * We control the following 2 angles:
-	 * - tilt angle, given by sqrt(x*x + y*y)
+	 * - tilt angle, given by sqrt(roll*roll + pitch*pitch)
 	 * - the direction of the maximum tilt in the XY-plane, which also defines the direction of the motion
 	 *
 	 * This allows a simple limitation of the tilt angle, the vehicle flies towards the direction that the stick
 	 * points to, and changes of the stick input are linear.
 	 */
-	_man_x_input_filter.setParameters(dt, _param_mc_man_tilt_tau.get());
-	_man_y_input_filter.setParameters(dt, _param_mc_man_tilt_tau.get());
-	_man_x_input_filter.update(_manual_control_setpoint.x * _man_tilt_max);
-	_man_y_input_filter.update(_manual_control_setpoint.y * _man_tilt_max);
-	const float x = _man_x_input_filter.getState();
-	const float y = _man_y_input_filter.getState();
+	_man_roll_input_filter.setParameters(dt, _param_mc_man_tilt_tau.get());
+	_man_pitch_input_filter.setParameters(dt, _param_mc_man_tilt_tau.get());
 
-	// we want to fly towards the direction of (x, y), so we use a perpendicular axis angle vector in the XY-plane
-	Vector2f v = Vector2f(y, -x);
+	// we want to fly towards the direction of (roll, pitch)
+	Vector2f v = Vector2f(_man_roll_input_filter.update(_manual_control_setpoint.roll * _man_tilt_max),
+			      -_man_pitch_input_filter.update(_manual_control_setpoint.pitch * _man_tilt_max));
 	float v_norm = v.norm(); // the norm of v defines the tilt angle
 
 	if (v_norm > _man_tilt_max) { // limit to the configured maximum tilt angle
@@ -200,7 +197,7 @@ MulticopterAttitudeControl::generate_attitude_setpoint(const Quatf &q, float dt,
 	Quatf q_sp = Eulerf(attitude_setpoint.roll_body, attitude_setpoint.pitch_body, attitude_setpoint.yaw_body);
 	q_sp.copyTo(attitude_setpoint.q_d);
 
-	attitude_setpoint.thrust_body[2] = -throttle_curve((_manual_control_setpoint.z + 1.f) * .5f);
+	attitude_setpoint.thrust_body[2] = -throttle_curve((_manual_control_setpoint.throttle + 1.f) * .5f);
 	attitude_setpoint.timestamp = hrt_absolute_time();
 
 	_vehicle_attitude_setpoint_pub.publish(attitude_setpoint);
@@ -316,8 +313,8 @@ MulticopterAttitudeControl::Run()
 				attitude_setpoint_generated = true;
 
 			} else {
-				_man_x_input_filter.reset(0.f);
-				_man_y_input_filter.reset(0.f);
+				_man_roll_input_filter.reset(0.f);
+				_man_pitch_input_filter.reset(0.f);
 			}
 
 			Vector3f rates_sp = _attitude_control.update(q);