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Page 380                        Zhang et al. Intell Robot 2022;2(4):371­90  I http://dx.doi.org/10.20517/ir.2022.26

               Then, the aforementioned optimization problem is converted into the minimization of the upper bound of the
               infinite-horizon objective function:
                                                    min                                               (27)
                                                     s.t.                  (25).



               A state feedback law   (  ) =         (  ) is applied to minimize the upper bound of the performance functions J   
                       ∑   
               and       =        (  )      , where       =             . Considering the inequality [Equation (24)] yields
                           =1
                                       [                                           ]
                                         (                   )                  
                                    (  )    (  ) + Δ  (  ) +       (  )             ∗ −      +    +              (  )
                                                                                
                                          (                  )   
                                  +  (  )    (  ) + Δ  (  ) +       (  )             (      (  ) + Δ      (  )) ∗   (  )  (28)
                                                           (                     )
                                  +  (  ) (      (  ) + Δ      (  ))         (  ) + Δ  (  ) +       (  )        (  )
                                        [                        ]
                                                          
                                  +  (  )  (      (  ) + Δ      (  ))       ∗ −       (  ) ≤ 0,
               which is equivalent to
                                             [      ]    [      ] [     ]
                                                 (  )   Π 1  Π 2     (  )
                                                                         ≤ 0,                         (29)
                                                 (  )   ∗   Π 3      (  )
                                         [                     ]                  
                                     Π 1 =   (  ) + Δ  (  ) +       (  )             ∗ −      +    +           
                                                                                 
                                         [                     ]                                      (30)
                                     Π 2 =   (  ) + Δ  (  ) +       (  )             [      (  ) + Δ      (  )]
                                                          
                                     Π 3 = [      (  ) + Δ      (  )]       ∗ −    .
                  is an identity matrix with appropriate dimensions. The inequality [Equation (28)] can be guaranteed as long
               as
                                                      [        ]
                                                        Π 1  Π 2
                                                                 ≤ 0                                  (31)
                                                        ∗   Π 3
               holds.

               Here, we introduce a lemma for use in the following sections.

               Lemma 3.3 [37] : For matrices Γ,    and    with appropriate dimensions and Γ = Γ, the following inequality
                                                                                
                                                                
                                                                       
                                                Γ +     (  )   +      (  )   ≤ 0                      (32)
               holds for all   (  )   (  ) ≤ 1 if and only if there is a positive scalar    such that
                                
                                                             1
                                                                   
                                                          
                                                  Γ +         +      ≤ 0.                             (33)
                                                               
               By Lemma 3.3, the following sufficient condition can be derived to guarantee the inequality [Equation (31)]:

                                  (           )   
                                                                                      
                    −       0                 +                 (        )  (        )  (     1       )  0  
                        −                                                               
                    ∗                                   0       0        0      (       2 ) 
                                                                                      
                    ∗    ∗         (     1     +      2    ) −        0  0  0     0   
                                      1        2                                      
                                                       −                                ≤ 0,    = 1, 2,  (34)
                    ∗    ∗              ∗                       0        0        0   
                                                                                      
                    ∗    ∗              ∗               ∗      −         0        0   
                                                                                      
                    ∗    ∗              ∗               ∗       ∗       −          0  
                                                                                      
                    ∗    ∗              ∗               ∗       ∗        ∗       −         
                                                                                      
               where    =     .
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