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This thesis develops theories for taking into account joint clearances and other error sources in linkage design. Position errors are broken down into translational and rotational position errors. Four different linkage designs are discussed: (1) Open-chain manipulators. (2) Planar four-bar linkages with four design positions. (3) Planar four-bar linkages with an unlimited number of design positions. (4) Spatial six-bar linkages with an unlimited number of design positions.
Position errors in manipulators are taken to include those due to parameter, joint, and elastic errors. These are integrated into an error propagation model, which determines the position errors of the end link. An error calibration method is devised to eliminate the effect of these errors. Coupler position errors of planar four-bar linkages are formulated and their relationships to the transmission angles are identified. The four-bar transmission angle is studied, and a computational method is developed to determine the linkage which yields the minimum position errors. A numerical example is presented. For positions guidance problems where exact solution do not exist, position errors are expressed as functions of the crank parameters. Techniques are applied to find the cranks which yield minimum position errors in a least-squares sense.