Research On Tendon-Electromagnetic Force Coupling Driven Flexible Robot

Compared with traditional surgical instruments,flexible robots have the advantages of absorbing vibration interference by passively deforming,and achieving complex motion with multiple degrees of freedom by continuously deforming.In recent years,they are often used in minimally invasive surgical treatment.Currently,throat diseases frequently occur due to air pollution and increased smoking population.Due to the complexity of the throat physiological structure,conventional surgical methods are risky and difficult.However,the existing flexible robots have the disadvantage of insufficient rigidity,so they are difficult to apply to throat surgery.On this basis,this paper proposes a flexible robot driven by tendon-electromagnetic force coupling.The robot adopts the electromagnetic variable stiffness method based on the friction method,and adjusts the overall stiffness of the robot manipulator by controlling the energization intensity of the variable stiffness module in the manipulator,so as to compensate for the shortage of insufficient rigidity of the flexible robot.First of all,by analyzing of the throat surgery process,this paper has determined the design points and design indicators of the robot,carried out a detailed structural design of the robot,proposed the overall structure of the robot and explained its sub-modules in detail.Then,Ansys Workbench was used to analyze the displacement and stress of the components with greater force in the structure to ensure the strength of the structure.Secondly,according to the theory of "triple space" and the assumption of uniform bending in the constant curvature model of the flexible robot,we carried out the kinematics modeling and simulation of the joint space,task space and driving space of the robot manipulator,and respectively used the analysis Method and numerical-based Monte Carlo method to draw the working space of the manipulator.On the basis of kinematics modeling,the robot is statically analyzed to obtain the static model of the tendon tension and the stiffness model of the manipulator,which provides theoretical support for the electromagnetic variable stiffness.Then,a model correction control method based on error analysis that combines data and model is proposed.It uses curve fitting and BP neural network to model on error compensation function under the condition of single variable of expected bending angle and two variables of expected bending angle-end load.Finally,combining the kinematics model and the tendon statics model to select and calculate the main components,we build a software and hardware experiment platform,and perform kinematic model verification experiments,variable stiffness evaluation experiments and control method verification experiments on the robot manipulator.The experimental results show that the the error level of kinematic model is equivalent to that of current researches,the electromagnetic variable stiffness module can increase the bending stiffness of the manipulator by up to 48%,and under the model modification control method,the bending posture error of the manipulator under load is less than 2.5°,which is much smaller than the error of the control method without modification function.