Non-constant Curvature Modeling Method Of A Tendon-driven Continuum And The Accuracy Detection Research

The development of minimally invasive surgery puts forward higher requirements for surgical robots.The continuum robot has unique adaptability to complex environments and has been successfully applied in various minimally invasive surgery.The continuum robot brings significant flexibility,but also brings the problems of difficult control and diff-icult to predict the position.At present,domestic and foreign scholars have made certain achievements in the continuum robot modeling,but the deformation study of large deflection for the tendon-driven continuum can not meet the needs of precision control.In this paper,based on the Cosserat rod theory,the geometrical deformation,mechanical properties and constitutive equations of the filament-driven continuum are systematically studied.The verification of the non-constant curvature model is successfully completed.Finally,a non-contact motion accuracy detection method for continuum is proposed and error analysis is carried out.The specific content of this article is as follows:Firstly,according to the large deflection deformation characteristics of the continuum robot as a nonlinear multi-input and multi-output system,the modeling direction of non-constant curvature is determined.Based on the Cosserat rod theory,the force system of the tendon-drive continuum is elaborated,and the mapping relationship from the kinematics and mechanics of the tendon to the deformation of the continuum is completed.The scheme can not only simulate the nonlinear deformation of the slender continuum,but also estimate the friction brought by the tendon drive,which provides a rich theoretical basis for the position prediction of the continuum.Secondly,a root-finding algorithm is designed for solving the three-dimensional nonlinear mathematical model,and the two-dimensional simplification of a pair of tendon drives is carried out,and I estimate the simple elastic backbone force model accuracy.Subsequently,a single backbone continuum structure is designed.As an experimental object to verify the non-constant curvature model,the experimental test of the driving force of tendons and the force at the end of the continuous body is completed,and the accuracy of the model is proved.Finally,based on the mathematical model analysis of the continuum,a non-contact detection method for the motion accuracy of the continuum is proposed.Using the lens imaging principle and image processing method,the experiment of measuring the motion accuracy of the continuous body and the experimental error analysis are carried out.