feat(follow_target): expose velocity filter gain as tunable parameter FLW_TGT_VG

The TargetEstimator's velocity beta coefficient was hardcoded as 0.9 * beta_p.
Introduce FLW_TGT_VG (default 0.9, range 0.1–1.0) so operators can tune the
velocity estimate's smoothness vs. responsiveness independently of FLW_TGT_RS.

Signed-off-by: Claude <noreply@anthropic.com>

src/modules/flight_mode_manager/tasks/AutoFollowTarget/follow_target_estimator/TargetEstimator.cpp

@@ -194,7 +194,7 @@ void TargetEstimator::update_filter_gains(filter_gains_s &filter_gains) const
 	// From alpha-beta-gamma filter equations: G = 1-beta^3
 	// Therefore: beta = (1-Gp)^(1/3) = (1-(1-responsiveness))^(1/3) = (r)^(1/3)
 	const float beta_p = powf((filter_gains.responsiveness), 1.0f / 3.0f);
-	const float beta_v = 0.9f * beta_p; // velocity fusion gain is slightly lower. TODO: individual parameter?
+	const float beta_v = math::constrain(_param_flw_tgt_vg.get(), 0.1f, 1.0f) * beta_p;
 
 	// Estimator gains for horizontal position update
 	filter_gains.G_p = 1.0f - beta_p * beta_p * beta_p;

src/modules/flight_mode_manager/tasks/AutoFollowTarget/follow_target_estimator/TargetEstimator.hpp

@@ -203,7 +203,8 @@ protected:
 	matrix::Vector3f _vel_measurement_old{};
 
 	DEFINE_PARAMETERS(
-		(ParamFloat<px4::params::FLW_TGT_RS>) _param_flw_tgt_rs
+		(ParamFloat<px4::params::FLW_TGT_RS>) _param_flw_tgt_rs,
+		(ParamFloat<px4::params::FLW_TGT_VG>) _param_flw_tgt_vg
 	)
 
 	// Subscriptions

src/modules/flight_mode_manager/tasks/AutoFollowTarget/follow_target_params.yaml

@@ -12,6 +12,19 @@ parameters:
       min: 0.0
       max: 1.0
       decimal: 2
+    FLW_TGT_VG:
+      description:
+        short: Velocity fusion gain factor in Target Estimator
+        long: |-
+          Scales the velocity filter's beta coefficient relative to the position
+          beta derived from FLW_TGT_RS. Lower values make the velocity estimate
+          smoother but less responsive. At 1.0 position and velocity filters have
+          equal responsiveness.
+      type: float
+      default: 0.9
+      min: 0.1
+      max: 1.0
+      decimal: 2
     FLW_TGT_HT:
       description:
         short: Follow target height