Dynamic modeling and control of package yarn pulled by mobile manipulator
Objective With the continuous development of robotics and textile industry intelligence,the use of industrial robots to replace manual labor to complete all types of typical textile processing skills operations has become a new trend in the textile industry.However,in complex textile processing environments,the direct manipulation of flexible yarns by robots suffers from yarn morphology perception difficulties and spatial limitations.Therefore,a yarn-pulling manipulation control framework with an integrated robotic obstacle avoidance motion planning strategy is proposed to realize collision-free and smooth pulling manipulation of package yarn on the warping frame by the robot from the starting point to the target point.Method First,the dynamics model of yarn on the package surface is constructed;then the motion coupling relationship between the robot and the yarn is analyzed and the motion control equation of the robot pulling the yarn is given;furthermore,the improved adaptive goal-guided rapidly-exploring random trees(AGG-RRT)algorithm based on the axial strain constraints of the yarn is proposed;finally,the motion planning is out carried for the mobile composite manipulator,which prevents the yarn from overstretching while circumventing the obstacles.Results In simulation experiment 1,taking the mobile manipulator bypass from the front of the yarn frame to the back of the yarn frame as an example,the robot obstacle avoidance path search is simulated to test the obstacle avoidance ability when facing a large obstacle.The results show that after eight traversal collision detection and correction of the searched robot end collision-free path,a completely collision-free path in the robot joint space is obtained,and the movement process of the robot around large obstacles is shown,and the translation motion curves of the robot's mobile chassis and the joint motion curves of the manipulator are obtained.In simulation experiment 2,taking the mobile manipulator gripping the reserved yarn end of the package and pulling around the obstacle to the target point as an example,the simulation for searching the obstacle avoidance path of the robot pulling yarn is carried out.The results show that after eight traversal collision detection and correction of the searched robot end collision-free path,a completely collision-free path in the robot joint space is obtained,and the translation motion curves of the robot's mobile chassis and the joint motion curves of the manipulator are obtained.Furthermore,the collision-free path of the mobile manipulator is planned in the Cartesian coordinate system using S-shaped velocity curve to obtain the interpolation trajectory of the robot pulling yarn.Then,according to the dynamic model and the motion control equation,the spatial configuration and the overall axial strain of the yarn under each moving time step of the robot are obtained,and the obstacle avoidance motion process of robot pulling yarn is shown.The results show that the absolute value of the overall axial strain of each element of the yarn is smaller than the preset value.Conclusion Simulation results validate the ability of the obstacle avoidance algorithm to bypass large obstacles and show its applicability in complex textile processing environments.The successful planning of a collision-free trajectory for the robot pulling yarn and the effective control of the axial strain of the yarn demonstrate the effectiveness of the control framework,which can realize a collision-free and flexible hauling operation of the manipulator for the packaged yarn from the starting point to the target point.
NETL
NSTL
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