vulcan::dryden Namespace Reference

Classes
struct	FilterState
	Dryden forming filter state. More...
struct	FilterCoeffs
	Discretized Dryden forming filter coefficients. More...

Functions
template<typename Scalar>
Scalar	psd_longitudinal (const Scalar &omega, double sigma_u, double L_u)
	Dryden longitudinal PSD.
template<typename Scalar>
Scalar	psd_lateral (const Scalar &omega, double sigma, double L)
	Dryden lateral/vertical PSD.
template<typename Scalar>
FilterState< Scalar >	init_state ()
	Initialize filter state to zero.
FilterCoeffs	compute_filter_coeffs (const wind::TurbulenceParams< double > &params, double airspeed, double dt)
	Compute forming filter coefficients.
template<typename Scalar>
wind::GustVelocity< Scalar >	step (FilterState< Scalar > &state, const FilterCoeffs &coeffs, const Scalar &noise_u, const Scalar &noise_v, const Scalar &noise_w)
	Step the Dryden forming filter.
FilterCoeffs	mil_spec_coeffs (double altitude, wind::TurbulenceSeverity severity, double airspeed, double dt)
	Compute all filter coefficients for MIL-spec conditions.

Function Documentation

compute_filter_coeffs()

FilterCoeffs vulcan::dryden::compute_filter_coeffs ( const wind::TurbulenceParams< double > & params, double airspeed, double dt )

inline

Compute forming filter coefficients.

Discretizes the continuous-time Dryden forming filters for given airspeed and time step using the bilinear (Tustin) transform.

Continuous-time transfer functions:

• Longitudinal: H_u(s) = σ_u * sqrt(2V/πL_u) / (1 + L_u/V * s)
• Lateral: H_v(s) = σ_v * sqrt(V/πL_v) * (1 + sqrt(3)*L_v/V*s) / (1 + L_v/V*s)^2
• Vertical: H_w(s) = same form as lateral with w subscripts

Parameters

params	Turbulence parameters (σ and L values)
airspeed	True airspeed V [m/s]
dt	Time step [s]

Returns

Discretized filter coefficients

init_state()

template<typename Scalar>

FilterState< Scalar > vulcan::dryden::init_state

(

)

Initialize filter state to zero.

Template Parameters

Scalar

double or casadi::MX

Returns

FilterState with all zeros

mil_spec_coeffs()

FilterCoeffs vulcan::dryden::mil_spec_coeffs ( double altitude, wind::TurbulenceSeverity severity, double airspeed, double dt )

inline

Compute all filter coefficients for MIL-spec conditions.

Convenience function that combines mil_spec_params and compute_filter_coeffs.

Parameters

altitude	Altitude above ground level [m]
severity	Turbulence severity level
airspeed	True airspeed [m/s]
dt	Time step [s]

Returns

FilterCoeffs ready for simulation

psd_lateral()

template<typename Scalar>

Scalar vulcan::dryden::psd_lateral	(	const Scalar &	omega,
		double	sigma,
		double	L )

Dryden lateral/vertical PSD.

Φ_v(Ω) = σ_v² * (L_v/π) * [(1 + 3(L_v·Ω)²) / (1 + (L_v·Ω)²)²]

Same form for vertical component with w subscripts.

Template Parameters

Scalar

double or casadi::MX

Parameters

omega	Spatial frequency Ω [rad/m]
sigma	RMS turbulence intensity [m/s]
L	Scale length [m]

Returns

PSD value [m²/s²/(rad/m)]

psd_longitudinal()

template<typename Scalar>

Scalar vulcan::dryden::psd_longitudinal	(	const Scalar &	omega,
		double	sigma_u,
		double	L_u )

Dryden longitudinal PSD.

Φ_u(Ω) = σ_u² * (2L_u/π) * [1 / (1 + (L_u·Ω)²)]

Template Parameters

Scalar

double or casadi::MX

Parameters

omega	Spatial frequency Ω [rad/m]
sigma_u	RMS turbulence intensity [m/s]
L_u	Scale length [m]

Returns

PSD value [m²/s²/(rad/m)]

step()

template<typename Scalar>

wind::GustVelocity< Scalar > vulcan::dryden::step	(	FilterState< Scalar > &	state,
		const FilterCoeffs &	coeffs,
		const Scalar &	noise_u,
		const Scalar &	noise_v,
		const Scalar &	noise_w )

Step the Dryden forming filter.

Updates filter state and computes gust velocities given white noise input. The noise inputs should be independent standard normal random variables.

Template Parameters

Scalar

double or casadi::MX

Parameters

state	Current filter state (updated in-place)
coeffs	Pre-computed filter coefficients
noise_u	White noise input for longitudinal channel
noise_v	White noise input for lateral channel
noise_w	White noise input for vertical channel

Returns

Gust velocity (u_g, v_g, w_g)