Research On Motion Behavior And Grasp Performance Of Growing Capture Robot

With the development of the era of "robot+",the working environment faced by robots has become more unstructured,and the tasks faced by robots have become more diversified.In addition,the operational requirements of "human-machine-environment" integration in the context of intelligent manufacturing put forward the development requirements of mobile flexibility and interactive security for robot technology.Aiming at the adaptive and stable grasping operation requirements of non-cooperative targets in the unstructured environment,a bioinspired continuum robot based on the design concept of“forward growth,snake-like maneuver,web-like capture,entangled holding” is proposed in this paper.This bioinspired continuum robot is named as “growing capture robot”,which has the characteristics of large workspace,high flexibility,adaptive interaction and high stability of grasping.The research work on bionic mechanism analysis,configuration design optimization,motion theory modeling,dexterity characteristic analysis,grasping stability determination,and performance experiment of the growing capture robot were carried out in this paper.The main research contents are as follows:(1)Forming robot design scheme based on bionic concept.The movement mode and predatory behavior of common animals and plants were investigated,analyzed and classified to provide design inspiration for robots.Based on the body structure and movement mechanism of python and earthworm,the structure of a growing continuum robot arm is proposed.Based on the mechanism of spiders preying through web and pythons preying through winding,a bionic Web-like capture device(Web Gripper)is proposed.The structural composition and movement mechanism of biological muscles are analyzed to optimize the bionic tendon driver design and drive layout method,and the design scheme of the growing continuum robot arm based on “driven by gas and controlled by cable” is selected.(2)Establishing multi-level motion model of the growing robot arm.The motion relationship of the growing continuum robot arm is divided into "drive space-joint space-workspace" multiple motion levels,and the forward and inverse motion mapping relationships between the multiple motion levels are analyzed.By establishing the homogeneous matrix of pose transformation and analyzing the spatial geometric transformation relationship,the multi-level forward and inverse solution motion mapping relationship expression of the motion joint module with growth characteristics is formed.The multi-level kinematics analysis of the growing continuum robot arm provides a theoretical basis for the subsequent dexterity performance analysis and drive control of the robot arm.(3)Analyzing the variation law of the motion performance index of the growing robot arm.According to the multi-level forward and inverse kinematics mapping relationship model of the motion joint module,the numerical simulation of the motion position and attitude of the robot arm is carried out,and the workspace of the growing robot arm is analyzed.The velocity Jacobian matrix of the motion joint module is established,and the dexterity analysis of the motion joint module at different positions in the workspace is analyzed by using the motion dexterity index.The dexterity of the motion joint module in different directions is analyzed by solving the maneuverability of the motion joint module,and the difference of dexterity in different directions is visually displayed through the ellipsoid of the maneuverability,The change rule of rope length is analyzed to determine the range of the actuator,which provides a reference for the drive control of the follow-up motion joint module.(4)Analyzing the deformation and grasping stability of the Web Gripper.The deformation of soft fingers is analyzed based on the hypothesis theory of large deflection beam deformation.The numerical integration method is used to solve the shape curve of soft fingers,and the deformation analysis method of soft fingers is formed.The mechanism of shape closure and force closure of the Web Gripper in the semi-enveloping grasping mode and the full-enveloping grasping mode are studied.The continuous contact discretization method is used to analyze the force closure stability when the Web Gripper grasps some typical objects.The grasping stability of the Web Gripper under external force interference is analyzed quantitatively by absolute stability index.(5)Testing the motion function and grasping performance of the growing capture robot.The prototype of the growing capture robot was built to carry out performance test experiments,mainly including the expansion performance of the inflatable airbag,the load capacity of the inflatable airbag,the growth performance of the motion joint module,the theoretical error of the motion of the motion joint module,the growth performance of the robot arm and the motion performance of the robot arm.The performance test experiment of the Web Gripper was also carried out,focusing on the influence of cable layout method,soft finger installation angle,maximum holding force,opening and closing speed and the change of grasping caliber on the capture performance of the Web Gripper.Finally,the experiments of grasping and capturing are carried out,and the potential application fields and application prospects of the growing capture robot are further discussed.The growing capture robot based on the bionic design concept is proposed in this paper,which has good performance characteristics of "large workspace,high mobility,adaptive capture,and stable grasping".The growing capture robot is expected to meet the operational requirements of adaptive and stable grasping of noncooperative targets in the unstructured environment.It is expected to provide new ideas and methods for the design of continuum robots,and enrich the theoretical and technical system and engineering application prospects of continuum robots.