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4.2 Path Generation                                          175





                                                                       (4.2.2)




            To match these boundary conditions, it is necessary to use on [tk, t k+1] the
            cubic interpolating polynomial

                                                                       (4.2.3)


            which has four free variables. Then

                                                                       (4.2.4)


                                                                       (4.2.5)

            so that the acceleration is linear on each sample period.
              It is easy to solve for the coefficients that guarantee matching of the boundary
            conditions. In fact, we see that





                                                                       (4.2.6)



            This is solved to obtain the required interpolating coefficients on each interval
            [t k, t k+1].







                                                                       (4.2.7)




            Note that this technique requires storing the desired position and velocity at
            each sampling point in tabular form. A variant uses a higher-order polynomial
            to ensure continuous position, velocity, and acceleration at each sample
            time t k.


            Copyright © 2004 by Marcel Dekker, Inc.
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