Page 10 - Human Inspired Dexterity in Robotic Manipulation
P. 10

4     Human Inspired Dexterity in Robotic Manipulation


          Table 1.1 Which statistical test should be performed in each case
                                   Number of    Assumption of  Assumption
          Name of    Target        elements in  Distribution in  of variance in
          test       comparison    each group   each group   each group
          T-test      Two groups   No limitation  Nothing    Nothing
          Tukey-      Pairwise     No limitation  Normal     Homogeneity
            Kramer      differences
          Bonferoni/  Pairwise     Same         Normal       Homogeneity
            Dunn        differences
          Scheffe     No limitation  No limitation  Nothing  Nothing



          1.2.2 State Space Representation

          State space representation is conducted when modeling a system as a first-
          order differential equation of the input (u), output (y), and state (x). If
          the system is linear, the state and observation equations are respectively
          represented by

                                     _ x ¼ Ax + Bu
                                                                       (1.1)
                                     y5Cx + Du
          where A, B, C, D are the matrixes. It should be noted that D 5 0 for most of
          the cases because it is the feedthrough term. If the system is nonlinear, the
          state and observation equations are respectively represented by

                                      _ x ¼ fx, uÞ
                                          ð
                                                                       (1.2)
                                      y5gx, uÞ
                                          ð
             Here, one simple example is shown. The model of mass, damper, and
          spring is considered and illustrated in Fig. 1.1. Let x be the state, m be
          the mass, d be the damping coefficient, k be the spring coefficient, and f
          be the applied force. The equation of motion is then represented by




                                    k
                                           m         f

                                     d

                                                      x
          Fig. 1.1 Model of mass, damper, and spring.
   5   6   7   8   9   10   11   12   13   14   15