Page 98 - Introduction to Autonomous Mobile Robots
P. 98

Mobile Robot Kinematics

                                                             Y =Y I                             83
                                                              G
                                                                         x ˆ


                                                                    β
                                                      goal
                                                                             X =X I
                                                                              G
                               Y R
                                                  ρ
                                                    α
                                                       X R
                                                v

                                                θ

                                    ω            ∆x


                           Figure 3.19
                           Robot kinematics and its frames of interests.


                             The task of the controller layout is to find a control matrix  , if it exists
                                                                            K

                                     k 11  k 12  k 13
                                                             ,
                                                            (
                                K =                   with k =  kt e)                        (3.45)
                                                       ij
                                     k 21  k 22  k 23
                             such that the control of vt()  and ω t()

                                                R
                                 vt()     ⋅       x
                                 ω t()  =  Ke =  K y                                         (3.46)
                                                  θ


                             drives the error   toward zero. 2
                                          e
                                lim  et() =  0                                               (3.47)
                                t →  ∞

                           2. Remember that v(t) is always heading in the X  direction of the robot’s reference frame due to the
                                                             R
                           nonholonomic constraint.
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