q q&W w (11)where01 .2 [ ]Té ù-é ù = ê úë û ´ê úë ûωwW w w (12)ω = ωx ωy ωz T denotes the tri-axis gyroscope output;ω × is a 3 × 3 skew symmetric matrix given by00 .0z yz xy xw wwww wé ù-ê úé ù´ = -ê úë û ê ú-ê úë ûw (13)The next step is to convert continuous-time model repre‐sented by (11) into a discrete-time model. Let the systemsampling time be Ts, then the discrete-time model is givenby( )1 exp , 0,1,2,...