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The path following problem for kinematic models of wheeled robots governed by nonlinear nonstationary affine systems with scalar control is considered. The concept of a canonical representation for this problem is introduced. The path following problem in a canonical form is stated as that of stabilizing zero solution with respect to a part of variables and is easily solved by applying feedback linearization technique. The original problem is shown to reduce to a canonical form by applying a time-scale transformation and converting the intermediate affine system obtained to a normal form. It is noted that such a representation is not unique and depends on the choice of the time-scale transformation applied. Advantages and disadvantages of the three canonical representations obtained by means of three different, earlier applied time-scale transformations are discussed. An example of the path following problem described by an affine system with a nonstationary drift field is presented.