Dynamic Design Of A Novel5-Axis Hybrid Kinematic Machine Head

In recent years, hybrid kinematic machine tools, such as the well-known Triceptrobot and Sprint Z3head, have been found successful applications into the aircraftmanufacturing industry. To meet the great demand of domestic aircraft manufacturing,a novel5-axis hybrid kinematic machine head named Tricept-IV is taken as the objectof this thesis. The dynamic design methodology of its3-UPS/UPP parallel module ispresented, which includes the inverse kinematic analysis, kineto-elastodynamicmodeling, inherent characteristics analysis, dynamic response solution, and dynamicoptimum design. The following work has been accomplished:1. Inverse kinematic analysis. With the aid of vector method, the inversekinematic model is formulated. According to the desired movement of the end point,the position, velocity and acceleration of the active joints and the angular velocity andacceleration of the limbs are calculated. And then the rigid-body motions of eachelement node can be obtained.2. Kineto-elastodynamic modeling. The elasto-dynamic equations of each limbare formulated by utilizing the kineto-elastodynamics theory. To model the elasticdeformations more precisely, all the limbs are discretized into several spatial beamelements, while the DOF coupling technique is utilized to simulate the actuatedprismatic pairs, and the Hooke’s joints attached to the stationary platform are treatedas the skewed bearings. Then, the elasto-dynamic equations of the3-UPS/UPPmechanism are established with the aid of the motion equations of the movingplatform and the elastic deformations compatibility conditions.3. Inherent characteristic analysis and dynamic response solution. The undampedinherent characteristic of the3-UPS/UPP mechanism is analyzed, and the distributionof the natural frequency in the workspace is revealed. Based on the kinematic analysis,the dynamic response of the mechanism is solved with resort of the NEWMARKmethod. Morover, the motion errors caused by the elastic deformation and themaximum Von Mises stress of the mechanism are analyzed.4. Dynamic optimum design. To minimize the total mass of the3-UPS/UPPmechanism, the sectional parameters of each component are optimized by utilizing theSQP algorithm, while the moving errors of the reference point and the strength conditions of each component are taken into consideration.The aforementioned research lays a theoretical basis for the development of thenovel5-axis hybrid machine head with excellent dynamic performance.