Parallel mechanism modal space control method suitable for ophthalmic microsurgery

Abstract

The invention discloses a six-degrees-of-freedom parallel mechanism modal space control method suitable for parallel computing. The problem of modal decoupling matrix solving of a parallel mechanism in global motion is converted into the problem of zero values of a nonlinear system of equations; on the basis, a modal frequency and characteristic value iterative numerical algorithm is constructed based on the Newton iterative algorithm; and the iterative algorithm is high in convergence rate, few in iterative time and suitable for multi-core processor parallel computing. A global modal space controller constructed by adopting the iterative algorithm not only solves a modal transition problem in large overall motion of the six-degrees-of-freedom parallel mechanism but also improves computational efficiency of the controller greatly.

Description

technical field [0001] The invention relates to the fields of medicine, control and machinery, in particular to a mode space control method of a parallel mechanism suitable for ophthalmic microsurgery. Background technique [0002] The six-degree-of-freedom parallel mechanism has been widely used in the medical field due to its small working space but high control precision. In the water sealing operation, the doctor manipulates the movement of the parallel robot under the guidance of the computer screen image. The positioning accuracy of the parallel robot reaches 0.01mm, which completely avoids the trembling that may occur during manual operation. Since then, the laboratory of the Humboldt University School of Medicine in Germany has also successfully performed brain surgery on patients using Delta parallel robots. In addition, T.Dohi et al. have developed a micro-operation parallel robot for brain surgery, and K.W.Grace of Northwestern University has developed A six-degr...

AI Technical Summary

Problems solved by technology

The six-degree-of-freedom parallel manipulator can be used for cataract intracapsular resection, posterior capsule polishing, vitrectomy, etc. However, for eyeball surgery and its strict positioning and trajectory tracking accuracy, the degree of freedom caused by the coupling characteristics of the parallel mechanism Coupling errors severely limit its use in ophthalmic surgery

[0004] However, the application of the current modal space controller is limited to the movement of the parallel mechanism in a small range in the middle position. The reason is that when the six-degree-of-freedom parallel mechanism moves in a large-scale global workspace, the modal decoupling Under the influence of pose parameters, it will lead to the occurrence of mode transition phenomenon, which makes the order of adjacent modes of the original system change.

The modal transition causes the mismatch between the modal control parameters of each order of the modal space controller and the corresponding mode after the transition, which makes the control characteristics of the modal space controller worse and even causes system oscillation.

[0005] In order to solve the modal transition problem, a global modal space controller based on the Jacobian iterative method has been proposed, but this method has a slow convergence speed when dealing with compound attitude motions, resulting in poor real-time performance of the controller.

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