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Adaptative high-gain extended Kalman filter and applications

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tel-00559107, version 1 - 24 Jan 2011<br />

2.6 On Adaptive High-<strong>gain</strong> Observers<br />

their observer construction can be found in articles like [16, 78, 79, 103] 16 . In the following<br />

we present the observer defined in [16], as it complies with the latest updates of their theory.<br />

Definition 19<br />

The system dynamics are:<br />

⎧ ⎛<br />

⎞ ⎛<br />

0 a2(y) 0 ... 0<br />

⎜ 0 0 a3(y) ... 0<br />

⎟ ⎜<br />

⎪⎨ ⎜<br />

˙x = ⎜<br />

.<br />

⎟ ⎜<br />

⎜ .<br />

.. .<br />

⎟ ⎜<br />

⎟ x + ⎜<br />

⎜<br />

⎟ ⎜<br />

⎝ 0 ... ... ... an(y) ⎠ ⎝<br />

⎪⎩<br />

0 ... ... ... 0<br />

y = x1 + δy(t).<br />

It is also denoted �<br />

where<br />

− y is the measured output,<br />

− the functions ai are locally Lipschitz,<br />

f1(u, y)<br />

f2(u, y, x2)<br />

f3(u, y, x2,x3)<br />

. . .<br />

fn(u, y, x2, ..., xn)<br />

˙x = A(y)x + b(y, x2, .., xn, , u)+∆( t)<br />

y = x1 + δy(t)<br />

⎞<br />

⎛<br />

⎟ ⎜<br />

⎟ ⎜<br />

⎟ ⎜<br />

⎟ + ⎜<br />

⎟ ⎜<br />

⎠ ⎝<br />

δ1(t)<br />

δ2(t)<br />

δ3(t)<br />

. . .<br />

δn(t)<br />

⎞<br />

⎟<br />

⎠<br />

(2.13)<br />

(2.14)<br />

− u is a vector in R nu representing the known inputs <strong>and</strong> a finite number of their derivatives,<br />

− the vector ∆(t) represents the unknown inputs, <strong>and</strong><br />

− δy is the measurement noise.<br />

The construction of the observer is based on some additional knowledge concerning the<br />

system:<br />

1. a function α of the output y such that 0 < ρ

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