Multibody Dynamics Analysis Of A Tendon-Driven Flexible Manipulator

With the development of the aerospace industry,space debris cleanup is becoming increasingly important.Compared with the traditional rigid robot,soft robots have self-adaptive and a high degree of redundancy,and have become one of the hot research fields in recent years.There are different driving modes for soft robots,including fluid elastic drive,tendon drive,thermal drive,optical drive,electric drive,memory alloy drive,and electroactive polymer drive.Recently,the research on soft robots focuses on the innovation of structures and driving modes.The research process is more consumable and time-consuming,and it is hard to achieve physical simulation in some particular environments,such as the non-gravity environment.In this paper,a multi-flexible-body dynamic modeling method is proposed to analyze the dynamic characteristics of a flexible capture device in grasping the target object in the nongravity environment and investigate the collision problem in holding the target object by using the flexible manipulator.Firstly,multi-rigid-body and multi-flexible-body dynamic models are established using the Lagrange equation and finite element method.Then,the motion trajectory and deformation states of the numerical model and the actual flexible arm are compared.Thirdly,the dynamic factors affecting the motion trajectory and deformation states of the model are analyzed using the high precision multi-flexible-body dynamic model.Finally,changes in internal forces and the influence of the driving force and damping ratio on the gripping range and impact force of the flexible arm while capturing the target object are numerically analyzed.The results show that the multi-flexible-body dynamic model established in this paper can reasonably well capture the motion trajectory and the whole deformation state of the tendondriving flexible manipulator.Both the driving force and damping ratio influence the gripping range and impact force of the tendon-driven flexible manipulator in the non-gravity environment.The impact force is positively correlated with the driving force and negatively correlated with the damping ratio.The trend of the gripping range is opposite to that of the impact force.In the grasping process of the capture device,a surge in the internal bending strength of the four flexible arms appears,and the inner strength near the contact position with the spherical target object is the largest.