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Page 264                         Sun et al. Intell Robot 2023;3(3):257-73  I http://dx.doi.org/10.20517/ir.2023.17

               For facilitating the proofs in the following sections, the following useful lemmas, which play important roles
               in our derivations, are presented first.

                                                                           
               Lemma 1  [33]  For any positive definite matrix    ∈ R   ×    with    =    , a scalar    > 0 and a vector function
                               
               ¤    : [−  , 0] → R such that the following integration inequality is well defined, i.e.,
                                          ∫                        [      −    ]
                                                                 
                                                 
                                        −      ¤    (  )   ¤(  )     ≤ −   (  )    (  )                (11)
                                                      
                                              −                     −       
                           [              ]
                       
               where    (  ) =    (  )    (   −   )  .
                                                [          ]
               Lemma 2  [34]  For any matrix    > 0,       > 0, scalars −   2 ≤   (  ) ≤ −   1, and a vector function
                                                           
               ¤    : [−   2 , −   1 ] → R such that the following integration inequality is well defined, i.e.,
                                 
                                                 ∫
                                                     −   1
                                                          
                                                               
                                        −(   2 −    1 )  ¤    (  )   ¤(  )     ≤
                                                    −   2
                                                               −       −                             (12)
                                                                            
                                                 −          ∗  2   −    −           −         (  )
                                                                            
                                                        ∗     ∗             
                                                                            
                                                          ]
                       
               where    (  ) =  [    (   −    1 )    (   −   (  ))    (   −    2 ) .
               3.1. Stability analysis
               Theorem 1 For some positive scalars   ,       ,      ,       (      ≤      ),   ,   , and matrix   , if there exist real symmetric
               positive definite matrices   ,      ,       (   ∈ {1, 2} ) and arbitrary matrices    for such that the follow inequalities hold
                                              [          ]       [        ]
                                                Π 11  Π 12            2    
                                          Π =              < 0,             > 0                        (13)
                                                 ∗   Π 22           ∗     2
               where
                                
               Π 11 = [(1, 1) =       +      + 2     +    1 −    −2           1,
                       (1, 2) =     −2           1 , (1, 3) =       , (1, 5) = −      ,
                       (1, 6) =     ,
                       (2, 2) =     −2        (   2 −    1 −    1 ) −    −2           2,  (2, 3) =    −2         (   2 −   ), (2, 4) =    −2          ,
                                           
                       (3, 3) =     −2         (   +    − 2   2 ) +         Φ,
                                                     
                       (3, 4) =     −2         (   2 −   ), (3, 5) = −         Φ,
                                                      
                       (4, 4) =     −2         (−   2 −    2 ), (5, 5) =         Φ − Φ,
                                                        
                       (6, 6) = −  ].
               Π 12 = [         1 Γ, (      −       )   2 Γ].
               Π 22 =         [−   1 , −   2 ],
               Γ     = [  , 0,     , 0, −    ,   ].

               Then, the NCS (9) under SS-ETC scheme (5) is ISS.
               Proof: See Appendix.


               From the proof of Theorem 1, it is clear that the convergence speed of the proposed event-triggered control
               algorithm is indicated by the parameter   . Namely, for a given convergence speed   , if a solution exists for
               the LMIs (13) under the proposed SS-ETC scheme (5), the convergence speed    is achieved by the designed
               controller   .
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