Automatic Analysis Algorithm Of Workpiece Locating Error Based On Directional Dimension Path

Fixture design account for a large proportion of the entire processing cycle, butthe traditional fixture design method has to rely on past experience or by means offixture design. This design method for mass production of the workpiece is notembody its disadvantages, but for small quantities of artifacts for a long period ofhigh design costs and become its main drawbacks. In addition, the design of thefixture personnel requirements are high, he needs to find a large amount of data andinformation. Positioning error as a major fixture design metrics directly determinesthe fixture design is good or bad. Using the dimension chain calculating positioningerror is a common method, the dimension chain automatic search problems are notwell resolved. Other calculation methods, such as probabilistic method, differentialmethod and so on, also are not universally applicable. It is in this background, thestudy of computer-aided positioning error generic algorithm is particularly important,and has been one of the core technologies of computer integrated manufacturingsystems,(Computer Integrated Manufacturing Systems, referred to as CIMS).Paper reviewed the development and present status of CAFD and positioningerror calculation method. Used the theory of kinematics positioning error caused theroot causes were discussed, and established work-piece positioning error model andpositioning components. And used the model to get the relation expression betweenposition error and the work-piece position offset. Through the relationship betweenthe expression element to calculate the positioning error, wherein the key step is tosolve the offset position of the work-piece. Put forward the concept of directionaldimension path of the offset position of the work-piece, and solved the positioningerror by solving the directed path. In addition, this paper verified the position errorcalculation method based on the directional dimension for all kinds of theapplicability of the locating scheme through a large number of instances,it providestheoretical supports for computer aided positioning error calculation.