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数学中国总编辑
TA的每日心情 | 衰 2016-11-18 10:46 |
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签到天数: 206 天 [LV.7]常住居民III 超级版主
群组: 2011年第一期数学建模 群组: 第一期sas基础实训课堂 群组: 第二届数模基础实训 群组: 2012第二期MCM/ICM优秀 群组: MCM优秀论文解析专题 |
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发表于 2011-11-28 10:48
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matlab下面的kalman滤波程序
" g O, V/ h! ~5 n8 fclear N=200; w(1)=0;
$ T% {' B. M4 L/ d) f3 Sw=randn(1,N)
: v2 X2 k [% E! p- f Ox(1)=0;
# h- T& E. m3 Sa=1; 0 t4 H4 r! a1 i# |8 N" U. _
for k=2:N; 7 }" C1 j9 h1 E' F1 l* C* k
x(k)=a*x(k-1)+w(k-1);
9 q* Y" n& ] O% \, ^end b0 ?* L) q2 ]# I9 `9 n5 d9 x" {
V=randn(1,N); 1 w# O" d8 Y7 H4 I' n8 l
q1=std(V);
# H/ M5 V$ H) SRvv=q1.^2; |$ n+ @' \# k+ \: V2 W3 \# y
q2=std(x); 5 n J9 t. o" t( s9 t0 w
Rxx=q2.^2;
' r) Z2 x% C- ~: ^q3=std(w); ' W' L* C; x1 n5 o5 Q& B
Rww=q3.^2; ! u+ q9 F0 L% B7 f% c U
c=0.2; 5 {8 o0 ~1 y5 R4 U* G; M- q5 a
Y=c*x+V; + w, C. z [; K
p(1)=0; & d7 @& _* d- ?
s(1)=0;
5 T8 S6 \8 e, d( k8 G- ^. `for t=2:N;
$ n! s/ ?. ~, M7 ep1(t)=a.^2*p(t-1)+Rww;
3 z* s1 s) G$ h4 y, W0 ~( @+ y9 ?b(t)=c*p1(t)/(c.^2*p1(t)+Rvv); 0 { J8 r, H& f) L
s(t)=a*s(t-1)+b(t)*(Y(t)-a*c*s(t-1));
/ l% P8 n3 y* z. @p(t)=p1(t)-c*b(t)*p1(t); 4 e2 y4 P( z5 e; J7 M0 E& h8 a
end , w0 W9 z$ k4 O n5 e9 z6 e# a
t=1:N;
# |6 i- r5 ]! F3 a+ Bplot(t,s,'r',t,Y,'g',t,x,'b'); : z! W: |) G8 C. |$ I$ O) ~
function [x, V, VV, loglik] = kalman_filter(y, A, C, Q, R, init_x, init_V, varargin)
7 Q3 M4 j& q9 j5 X$ c% Kalman filter. . q' u! U. B! }4 m* {
% [x, V, VV, loglik] = kalman_filter(y, A, C, Q, R, init_x, init_V, ...)
) W! x i- u% P! [9 J2 [9 \%
' D0 i/ _$ O) d0 r' `+ P' S% INPUTS: 6 w; r$ Z; O) o+ J( y! @3 G
% y(:,t) - the observation at time t
1 t+ i2 M* Y: M8 f6 a& `% A - the system matrix
4 ^- u( c9 M4 R. U% C - the observation matrix
e& G+ [5 s/ m9 F. v: b# }0 J% Q - the system covariance
4 @' f! }& z- `- }; ^( D0 d% R - the observation covariance
7 y1 f- @3 K; ]! ^4 f8 [* C% init_x - the initial state (column) vector
5 g8 W- h# V `/ p @+ R: c% init_V - the initial state covariance , q, J1 g0 Y# g' I
%
* z1 W" j' ^! }# ~: O% OPTIONAL INPUTS (string/value pairs [default in brackets])
$ u. y& i, P3 ~% 'model' - model(t)=m means use params from model m at time t [ones(1,T) ] 5 b; p9 A* e0 _3 q& q* A
% In this case, all the above matrices take an additional final dimension,
. |) X- G3 }$ X0 a% j0 c% i.e., A(:,:,m), C(:,:,m), Q(:,:,m), R(:,:,m).
0 Z" T3 l2 i6 s% n) c9 ~% However, init_x and init_V are independent of model(1).
& g' v" C9 W8 S- ^- ^6 A$ [% 'u' - u(:,t) the control signal at time t [ [] ] 2 u' U0 |% P2 s7 ?) z9 Q9 a
% 'B' - B(:,:,m) the input regression matrix for model m
( ]8 v& ~- z$ ]) l# w7 V% : G( S* L% i- w8 {
% OUTPUTS (where X is the hidden state being estimated)
# m8 y* u" T. @6 M' b( \. k7 ^% x(:,t) = E[X(:,t) | y(:,1:t)]
1 X F: L9 T3 g2 o% V(:,:,t) = Cov[X(:,t) | y(:,1:t)]
; y% }+ W, X% ]( q$ a% VV(:,:,t) = Cov[X(:,t), X(:,t-1) | y(:,1:t)] t >= 2
7 K# E, V: M" w) i% loglik = sum{t=1}^T log P(y(:,t)) . u# s A$ U; f: {/ N
%
1 Q# v/ f+ b1 p* A# o! m6 d% If an input signal is specified, we also condition on it: , C+ L2 G: z: e" D5 x4 @6 S
% e.g., x(:,t) = E[X(:,t) | y(:,1:t), u(:, 1:t)] 6 X8 u, G$ l. m9 q, y
% If a model sequence is specified, we also condition on it:
) d% ?" P& }2 C2 p+ G: _+ Y' p! E9 k0 @% e.g., x(:,t) = E[X(:,t) | y(:,1:t), u(:, 1:t), m(1:t)] 5 b) c' y% D# t" E
[os T] = size(y);
j9 A7 c4 N, Yss = size(A,1); % size of state space 5 j& @2 v9 p& c) p& }) Y
% set default params
5 K5 w5 ]" _* ^model = ones(1,T); " E- N7 a# }; ~ c2 R ?
u = []; 6 @7 y8 h" ~* n
B = [];
& m! g0 F( m1 J6 l$ I% Zndx = [];
) o0 ^& b7 {1 P) _+ b/ _args = varargin; / g% I! R1 H0 E' o
nargs = length(args); # |3 x6 ]5 M3 L7 B5 Y! @9 I! [! x
for i=1:2:nargs 9 _ C# m) X* w. k1 O7 i
switch args
Y/ T# f8 k: w1 [case 'model', model = args{i+1};
8 [" G# ~3 V/ R, Wcase 'u', u = args{i+1}; - u, \6 X& F* A! V, _: e
case 'B', B = args{i+1};
0 C" T0 E" [4 x3 |- m( fcase 'ndx', ndx = args{i+1}; ; A" H1 f7 }9 ?( l) t
otherwise, error(['unrecognized argument ' args])
- j% J) s u& _# @' bend ' W) h% |. }8 v E a9 G
end
$ y. Y3 D ?" q9 k4 y rx = zeros(ss, T); : {: _) G+ R4 X' d# P: R8 |& y
V = zeros(ss, ss, T);
( A+ n1 i3 Z- \5 Y& L6 F3 x# XVV = zeros(ss, ss, T); + J- B. X0 k; F" V
loglik = 0;
* E5 S/ `+ }* u# g- [8 P- `" cfor t=1:T m = model(t); ; b& {% ~3 E( `" q" s1 u
if t==1 %prevx = init_x(:,m); 6 k8 Y3 _( k) S( x* _+ ?
%prevV = init_V(:,:,m); 6 t- X- R, X4 }' ~5 a8 e3 J
prevx = init_x; 7 g7 i3 S" Q, {# b& d! g$ c
prevV = init_V;
# I( S5 I& f+ ?( T5 @ X( L* b! kinitial = 1;
+ Q. ~# j# S6 V) G felse prevx = x(:,t-1);
& b$ Y7 i2 S1 T* t2 d% Z3 ]prevV = V(:,:,t-1);
0 L$ V7 [5 Q' B0 Xinitial = 0; ; m' ^7 w$ A4 L) U' w
end
/ W; E$ D$ c0 T) r; d" b7 t3 Jif isempty(u)
) P, I* Z+ H; |- i[x(:,t), V(:,:,t), LL, VV(:,:,t)] = ... " I+ f- [5 }0 s: ~4 c
kalman_update(A(:,:,m), C(:,:,m), Q(:,:,m), R(:,:,m), y(:,t), prevx, prevV, 'initial', initial); else " i0 |: ~: a7 R( o8 ^+ h2 ^
if isempty(ndx) [x(:,t), V(:,:,t), LL, VV(:,:,t)] = ... 8 }& N+ |7 |/ L4 I
kalman_update(A(:,:,m), C(:,:,m), Q(:,:,m), R(:,:,m), y(:,t), prevx, prevV, ... 'initial', initial, 'u', u(:,t), 'B', B(:,:,m));
2 T& x Y4 q' b- belse 4 g3 c3 ] S! J. @# W
i = ndx;
' B. C- h; e* R& q) O- \" m% copy over all elements; only some will get updated x(:,t) = prevx;
( A6 d/ U4 r, N# U. P8 z0 t: fprevP = inv(prevV); 0 l8 N7 c( o4 h& b/ ?
prevPsmall = prevP(i,i);
, r; b" {7 V, w, o! C5 ^2 QprevVsmall = inv(prevPsmall);
U% i, N: w4 P[x(i,t), smallV, LL, VV(i,i,t)] = ... kalman_update(A(i,i,m), C(:,i,m), Q(i,i,m), R(:,:,m), y(:,t), prevx(i), prevVsmall, ... 'initial', initial, 'u', u(:,t), 'B', B(i,:,m)); ) t) [8 f8 r- V- k
smallP = inv(smallV);
& f! S% ?# |& s: EprevP(i,i) = smallP; / W" q6 j$ r& w7 R0 o
V(:,:,t) = inv(prevP); 9 `3 e3 r) p& T( U, W: u
end
- m- ?8 d- `$ Xend 7 s P9 J- j3 N0 l, a, R3 E3 g
loglik = loglik + LL;
9 c7 J! U7 D! h: S5 y( w* lend |
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