Modeling and Identification Approach for Tripod Machine Tools

To improve stiffness and workspace of tripod machine tools,a device called tripod machine tool was proposed with five degrees of freedom.First,the structure and pose description of the tripod machine tool were introduced,and then its backward and forward kinematics models were analyzed.To identify parameters of the tripod machine tool,aparameter identification method based on an error-sensitive analysis was presented.Then geometrical structural identification model was deduced by establishing the pose relative error model at two different points of the tripod machine tool.The method employed a sensitivity matrix by using a difference operator to explain pose changes of the tripod machine tool with respect to its main geometrical structural parameters.Finally,the position error of a tripod machine tool was reduced from 1.74 mm to 0.44 mm.Therefore,the proposed identification method was verified to be effective and feasible.