consider acceleration ramp-up time

src/lib/CollisionPrevention/CollisionPrevention.cpp

@@ -65,7 +65,7 @@ bool CollisionPrevention::initializeSubscriptions(SubscriptionArray &subscriptio
 	return true;
 }
 
-void CollisionPrevention::calculate_constrained_setpoint(Vector2f &setpoint, const float max_acc)
+void CollisionPrevention::calculate_constrained_setpoint(Vector2f &setpoint, const float max_acc, const float curr_vel)
 {
 	const obstacle_distance_s &obstacle_distance = _sub_obstacle_distance->get();
 
@@ -91,8 +91,10 @@ void CollisionPrevention::calculate_constrained_setpoint(Vector2f &setpoint, con
 					float angle = math::radians((float)i * obstacle_distance.increment);
 
 					//max admissible velocity in current bin direction: v = sqrt(2 * a * d), where d is the distance to standstill
-					//a is the constant acceleration and v the current velocity. We use a = a_max/2 to stay well within the limits
-					float vel_max_sqrd = math::max(0.f, max_acc * (distance - _param_mpc_col_prev_d.get()));
+					//a is the constant acceleration and v the current velocity. We use a = a_max/2  and j = j_max/2 to stay well within the limits
+					float acceleration_distance = 2.f * curr_vel * max_acc / _param_mpc_jerk_max.get();
+					float distance_to_standstill = math::max(0.f, distance - _param_mpc_col_prev_d.get() - acceleration_distance);
+					float vel_max_sqrd = max_acc * distance_to_standstill;
 
 					//split current setpoint into parallel and orthogonal components with respect to the current bin direction
 					Vector2f bin_direction = {cos(angle), sin(angle)};
@@ -142,11 +144,11 @@ void CollisionPrevention::calculate_constrained_setpoint(Vector2f &setpoint, con
 }
 
 void CollisionPrevention::modifySetpoint(Vector2f &original_setpoint, const float max_speed,
-		const float max_acc)
+		const float max_acc, const float curr_vel)
 {
 	//calculate movement constraints based on range data
 	Vector2f new_setpoint = original_setpoint;
-	calculate_constrained_setpoint(new_setpoint, max_acc);
+	calculate_constrained_setpoint(new_setpoint, max_acc, curr_vel);
 
 	//warn user if collision prevention starts to interfere
 	bool currently_interfering = (new_setpoint(0) < original_setpoint(0) - 0.05f * max_speed

src/lib/CollisionPrevention/CollisionPrevention.hpp

@@ -68,7 +68,8 @@ public:
 
 	bool is_active() { return _param_mpc_col_prev_d.get() > 0; }
 
-	void modifySetpoint(matrix::Vector2f &original_setpoint, const float max_speed, const float max_acc);
+	void modifySetpoint(matrix::Vector2f &original_setpoint, const float max_speed, const float max_acc,
+			    const float curr_vel);
 
 private:
 
@@ -84,11 +85,12 @@ private:
 	hrt_abstime _last_message;
 
 	DEFINE_PARAMETERS(
-		(ParamFloat<px4::params::MPC_COL_PREV_D>) _param_mpc_col_prev_d /**< collision prevention keep minimum distance */
+		(ParamFloat<px4::params::MPC_COL_PREV_D>) _param_mpc_col_prev_d, /**< collision prevention keep minimum distance */
+		(ParamFloat<px4::params::MPC_JERK_MAX>) _param_mpc_jerk_max /**< maximum jerk allowed in position controller*/
 	)
 
 	void update();
 
-	void calculate_constrained_setpoint(matrix::Vector2f &setpoint, const float max_acc);
+	void calculate_constrained_setpoint(matrix::Vector2f &setpoint, const float max_acc, const float curr_vel);
 
 };

src/lib/FlightTasks/tasks/ManualPosition/FlightTaskManualPosition.cpp

@@ -134,7 +134,7 @@ void FlightTaskManualPosition::_scaleSticks()
 
 	// collision prevention
 	if (_collision_prevention.is_active()) {
-		_collision_prevention.modifySetpoint(vel_sp_xy, _velocity_scale, _param_mpc_acc_hor_max.get());
+		_collision_prevention.modifySetpoint(vel_sp_xy, _velocity_scale, _param_mpc_acc_hor_max.get(), _velocity.norm());
 	}
 
 	_velocity_setpoint(0) = vel_sp_xy(0);