This chapter begins with a description of the different types of mechanisms that are generally used, especially in industrial robots. The parameters and variables of the mechanisms are defined and the degrees of freedom are calculated. Two methods to model a mechanism are presented. We show that in the Denavit-Hartenberg method, the attachment of local coordinate frames to the links is precisely specified, and relative to these frames a minimum number of translational and rotational parameters that describe the relative pose of two neighboring links are defined. In the so-called method of Vector Parameters, link and joint vectors are used to determine the geometry of the mechanism. As the reference position of a mechanism is a free choice, this method enables us to select the most appropriate reference position with respect to the requirements of the robot task.
KeywordsCoordinate Frame Parallel Mechanism Kinematic Chain Reference Position Rotational Joint
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