Motion Planning And Vibration Control For Flexible Continuum Manipulators

Flexible continuum manipulators have been used in many applications,including surgical robotics and field robotics,due to their unique advantage of flexibility and the capability to execute whole-arm manipulation.However,these advantages at the same time pose many challenges to motion planning and vibration control,which is the focus of this paper.Abstracts of researches in this paper are listed as follows:The redundancy resolution of the flexible continuum manipulator is studied.As the core elastic structure of the flexible continuum manipulator is deformed during motion,a redundancy resolution which minimizes the infinity norm of the curvature vector is proposed.This redundancy resolution uses the sequential quadratic programming algorithm to minimize the infinity norm of the curvature vector while taking the end motion and joint speed limit as the constraints.In the numerical simulation,the proposed method can reduce the maximum curvature value of the flexible continuum manipulator compared with the pseudo-inverse method,thereby reducing the stress in the core elastic structure.Moreover,when there is a certain maximum curvature limit,the minimizing curvature infinity norm solution can achieve a larger range of motion.Then,a planar fourdegree-of-freedom cable-driven continuum manipulator is built for experimental verification,which proves the effectiveness of the proposed method.A modified generalized Jacobian matrix method is proposed for the whole-arm grasping operation of the floating-base continuum robots.First,the modified generalized Jacobian matrix method is developed by combining the momentum conservation equation and the kinematic equation.Then,numerical simulations show that when the modified generalized Jacobian matrix method is not used,the grasping area changes due to the rotation of the base.Before the complete grasp is formed,the flexible arm collides with the target,pushing the floating target away.When the modified generalized Jacobian matrix method is utilized,the position and attitude of the grasping section are not changed,thereby realizing safe whole-arm grasping operation.Finally,the performance of the proposed method with different base inertia and configuration,as well as its application on the rigid-link manipulator are discussed.A tunable vibration absorber with liquid elastic chamber(TVA-LEC)is proposed to suppress the vibration of the flexible continuum manipulator under external disturbance.It is formed by covering a rigid cylindrical chamber with two rubber membranes that act as springs and filling the chamber with incompressible liquid.A single-degree-of-freedom(SDOF)analytical model is developed for the proposed device with discussions on the tuning of its natural frequency.It is revealed that the natural frequency of the TVA-LEC can be tuned by regulating the liquid mass.The analytical model is then validated by experimental tests.Finally,the design of the TVA-LEC for a flexible continuum manipulator working in the environment of micro gravitation is discussed.The simulation shows that the vibration absorber can effectively attenuate the vibration and can adapt to the frequency change of the manipulator due to different payloads.