Performance Evaluation Index Framework Of Lower Mobility Parallel Manipulators

This dissertation presents a complete theoretical package for performance evaluation index framework of lower mobility parallel manipulators, optimal design criteria of high-stiffness and high-speed lower mobility parallel manipulators, and its application to the design of a Tricept-IV manipulator, a Licept manipulator and a LiTriang manipulator with independent intellectual property. The following contributions have been made.With the concept"Lock"and"Measure", the descriptions of velocity, force, energy, stiffness, accuracy, acceleration and actuated joint force transmission in the limb and among the limbs are carried out. This breakthrough idea leads to the possibility to formulate the performance evaluation index framework of lower mobility parallel manipulators having the same mathematical definition.For the high-stiffness and high-speed lower mobility parallel manipulators, a novel optimal design criteria of equal-physical quantity is proposed whose objective function are concerned performance indexes, the constraint conditions are geometric constraints and other performance indexes.Based on the definitions of the local and global performance evaluation indexes for velocity, force, energy, stiffness, accuracy, the first-order motion performance evaluation index framework is formulated. Besides, the singularities of velocity, force, energy, stiffness are defined respectively.For the high-stiffness lower mobility parallel manipulators, the optimal design criteria of equal-physical quantity is applied, whose objective function are energy and stiffness performance indexes, the constraint conditions are geometric constraints and velocity, force, accuracy performance indexes, and then the optimal parameter domain is appeared by means of equal-physical quantity criteria. This optimal design method is applied to design of Tricept-IV manipulator, which is used in the assembly of automobile engine.Based on the definitions of the local and global performance evaluation indexes for acceleration and actuated joint force, the second-order motion performance evaluation index framework is formulated. Besides, the singularities of acceleration and actuated joint force are defined respectively.For the high-speed lower mobility parallel manipulators, the optimal design criteria of equal-physical quantity is applied, whose objective function are energy and actuated joint force performance indexes, the constraint conditions are geometric constraints and velocity, force, accuracy, acceleration performance indexes, and then the optimal parameter domain is appeared by means of equal-physical quantity criteria. This optimal design method is applied to design of Licept and LiTriang manipulator, which is used in high-speed laser cutting and high-speed pick-and-place operations, respectively.