Data Structures
struct	servo_t

struct	sho_t

union	servo_t.__unnamed__

union	servo_t.__unnamed__

Functions
dcell *	servo_optim (real dt, long dtrat, real al, real pmargin, real f0, real zeta, int servo_type, const dmat psdin, const dmat sigma2n)

real	servo_optim_margin (real dt, long dtrat, real al, real pmargin, real f0, real zeta)

dmat *	servo_cl2ol (const dmat *psdcl, real dt, long dtrat, real al, real gain, real sigma2n)

real	servo_residual (real noise_amp, const dmat psdin, real dt, long dtrat, real al, const dmat *gain, int servo_type)

servo_t *	servo_new (anyarray merr, const dmat ap, real al, real dt, const dmat ep)

servo_t *	servo_new_scalar (anyarray merr, real ap, real al, real dt, real ep)

servo_t *	servo_new_sho (anyarray merr, const dmat ap, real al, real dt, const dmat ep, real f0, real zeta)

int	servo_filter (servo_t *st, const anyarray merr)

void	servo_add (servo_t *st, const anyarray madj, real alpha)

void	servo_output (const servo_t *st, panyarray out)

dmat *	servo_test (dmat mideal, real dt, int dtrat, dmat sigma2n, dmat *gain)

void	servo_reset (servo_t *st)

void	servo_free (servo_t *st)

sho_t *	sho_new (real f0, real zeta)

void	sho_free (sho_t *sho)

void	sho_step (panyarray xout, sho_t *sho, anyarray xi, real dt, int average)

void	sho_reset (sho_t *sho)

dmat *	sho_filter (const dmat *xi, real dt, real f0, real zeta, int average)

Detailed Description

Routines for servo optimization, filtering, etc.

Data Structure Documentation

◆ servo_t

struct servo_t

Struct for servo filtering

Collaboration diagram for servo_t:

Data Fields
union servo_t	__unnamed__
union servo_t	__unnamed__
cell *	mlead	lead filter temporary storage
cell *	merrlast	recorded errro signal from last step
cell *	merrhist	Keep a short history of merr
int	initialized	is this data initialized
int	alint	Integral part of latency
real	alfrac	Fractional latency
dmat *	ap
dmat *	ep
real	dt
sho_t *	sho

◆ sho_t

struct sho_t

struct for state space modeling of a second order harnomic oscillator with resonance frequency of f0 and damping ratio of zeta.

Collaboration diagram for sho_t:

Data Fields
real	dt
real	c1
real	c2
cell *	dx
cell *	x
cell *	ddx
cell *	ytmp

◆ servo_t.unnamed

union servo_t.__unnamed__

Collaboration diagram for servo_t.__unnamed__:

Data Fields
cell *	mint	second integrator. It is array to accomodate multiple ap's
dccell *	mintc
dcell *	mintd

◆ servo_t.unnamed

union servo_t.__unnamed__

Collaboration diagram for servo_t.__unnamed__:

Data Fields
cell *	mpreint	first integrator or other value.
dcell *	mpreintc
dmat *	mpreintd

Function Documentation

◆ servo_optim()

dcell* servo_optim	(	real	dt,
		long	dtrat,
		real	al,
		real	pmargin,
		real	f0,
		real	zeta,
		int	servo_type,
		const dmat *	psdin,
		const dmat *	sigma2n
	)

Optimize the servo gains by balancing errors due to noise and signal propagation.

Written: 2010-06-11

Tested OK: 2010-06-11

2011-01-17: The optimization process is quite slow, but the result is only dependent on the sigma2n and fs. psdin does not change during the simulation. Built a lookup table in skyc using various sigma2n and interpolate to get ress, resn, and gain.

2012-03-28: Cleaned up this routine. groupped similar calculations together. Change g2=a from g=sqrt(a)

2013-06-27: The maximum gain should not be limited to 0.5 beause it is later scaled by sqrt(a);

sigma2n is a dmat array of all wanted sigma2n. Returns a zfarray of a dmat of [g0, a, T, res_sig, res_n]

The upper end of frequency must be nyquist freq so that noise transfer can be computed. But we need to capture the turbulence PSD beyond nyquist freq, which are uncorrectable.

2022-03-04: added SHO response parameter.

◆ servo_optim_margin()

real servo_optim_margin	(	real	dt,
		long	dtrat,
		real	al,
		real	pmargin,
		real	f0,
		real	zeta
	)

Optimize integrator control with optional SHO response (output) to have correct phase margin (pi/4) when abs(Hol)==1.

◆ servo_cl2ol()

dmat* servo_cl2ol	(	const dmat *	psdcl,
		real	dt,
		long	dtrat,
		real	al,
		real	gain,
		real	sigma2n
	)

Convert Closed loop residual PSD back to OL psd using rejection transfer function: PSD_OL=PSD_CL/Hrej-sigma2n/F_nyquist; Only implemented for integrator.

◆ servo_residual()

real servo_residual	(	real *	noise_amp,
		const dmat *	psdin,
		real	dt,
		long	dtrat,
		real	al,
		const dmat *	gain,
		int	servo_type
	)

Compute the residual error after servo rejection of a type II servo given the gain.

Written: 2010-06-11

Tested OK: 2010-06-11

◆ servo_new()

servo_t* servo_new	(	anyarray	merr,
		const dmat *	ap,
		real	al,
		real	dt,
		const dmat *	ep
	)

Initialize servo_t. al is additional latency

◆ servo_new_scalar()

servo_t* servo_new_scalar	(	anyarray	merr,
		real	ap,
		real	al,
		real	dt,
		real	ep
	)

Initialize servo_t with scalar ap and ep

◆ servo_new_sho()

servo_t* servo_new_sho	(	anyarray	merr,
		const dmat *	ap,
		real	al,
		real	dt,
		const dmat *	ep,
		real	f0,
		real	zeta
	)

Initialize servo_t with an sho

◆ servo_filter()

int servo_filter	(	servo_t *	st,
		const anyarray	_merr
	)

Applies type I or type II filter based on number of entries in gain.

◆ servo_add()

void servo_add	(	servo_t *	st,
		const anyarray	madj,
		real	alpha
	)

Adjust integrator content without shift.

◆ servo_output()

void servo_output	(	const servo_t *	st,
		panyarray	out_
	)

Create servo output. It handles st->alfrac. and outputs the averaged position over the integration period.

◆ servo_test()

dmat* servo_test	(	dmat *	input,
		real	dt,
		int	dtrat,
		dmat *	sigma2n,
		dmat *	gain
	)

test type I/II filter with ideal measurement to make sure it is implemented correctly.

◆ servo_reset()

void servo_reset ( servo_t * st )

reset the data to 0.

◆ servo_free()

void servo_free ( servo_t * st )

Free servo_t struct

◆ sho_new()

sho_t* sho_new	(	real	f0,
		real	zeta
	)

Second harmonic oscillator. Initialization. Equation is is d^x/dt^2+c1*dx/dt+c2*x=c2*xi State space model is |x'|' | -c1 -c2 | |x'| |xi| |x | = | 1 0 | | x| + c2 |0 | where x' is dx/dt and written as dx in struct. we use c2*xi so that it is in the same unit and scale as x.

Parameters

f0	Resonance frequency
zeta	Damping

◆ sho_step()

void sho_step	(	panyarray	xout_,
		sho_t *	sho,
		anyarray	xi_,
		real	dt,
		int	avg
	)

Second harmonic oscillator state space update. xi is driving position.
Second harmonic oscillator state space update. xi is driving position. Update the position after time dt. Also compute the average position between 0 and dt (for WFS integration) if avg is set.

sho->x +=dt*sho->dx;//update position ddx=sho->dx*(-sho->c1)+sho->x*(-sho->c2)+xi;//update speed sho->dx+=dt*ddx; //update speed

◆ sho_reset()

void sho_reset ( sho_t * sho )

Second harmonic oscillator. Reset.

◆ sho_filter()

dmat* sho_filter	(	const dmat *	x,
		real	dt,
		real	f0,
		real	zeta,
		int	avg
	)

Second harmonic oscillator. Filter a time series for testing.

Parameters

x	Input time series
dt	Input time series sampling
f0	Resonance frequency
zeta	Damping
avg	Average or not

Data Structures

Functions

Detailed Description

Data Structure Documentation

◆ servo_t

◆ sho_t

◆ servo_t.__unnamed__

◆ servo_t.__unnamed__

Function Documentation

◆ servo_optim()

◆ servo_optim_margin()

◆ servo_cl2ol()

◆ servo_residual()

◆ servo_new()

◆ servo_new_scalar()

◆ servo_new_sho()

◆ servo_filter()

◆ servo_add()

◆ servo_output()

◆ servo_test()

◆ servo_reset()

◆ servo_free()

◆ sho_new()

◆ sho_step()

◆ sho_reset()

◆ sho_filter()

◆ servo_t.unnamed

◆ servo_t.unnamed