Modeling And Stability Analysis Of Wheeled Mobile Multi-robot Coordinated Towing System

In recent years,the research of robot towing has become more and more popular,and has been widely used in many fields,such as municipal engineering,road and bridge construction and ship loading and unloading cargo.With the increasing demand of the load,accuracy,safety and stability of the towing operation in social production tasks,the scope,bearing capacity and flexibility of a single robot are limited,so it is difficult to complete the high load and complex towing task.At the same time,with the rapid development of single crane in material,structure and control,the multi-robot towing is becoming more and more mature,and multi-machine coordinated towing is also more and more applied to practical engineering.For multi-robot towing,most scholars study the multi-machine coordinated towing system with fixed base and the coordinated towing system of multi-robot in the air.The research on the coordinated towing of mobile multi-robot is relatively few,especially for the coupling joint type manipulator of mobile platform,so the research in this field has a broad research prospect.This paper first describes the spatial configuration of the coordinated towing system of wheel mobile multi-robot and analyzes the forward and inverse kinematics of the mobile manipulator and the parallel system.The dynamic process of the mobile manipulator and the towing system is established by Lagrange method and Newton-Euler method respectively.The force / moment of the manipulator acting on the mobile platform under the static,static and dynamic forces are analyzed in detail.Then,the error analysis theory is applied to the error research of the coordinated towing system of the wheel mobile multi-robot.Based on the kinematic model of the coordinated towing system of the wheel mobile multi-robot,the error model of the mobile manipulator arm and the parallel flexible cable system is established by using the matrix total differential method,and the comprehensive error model is established combining with the spatial motion relationship of the system.Then,the error sensitivity model of the system error source is established,and the influence of 36 error sources on the output of the system is analyzed.The sensitivity coefficient standard is worth setting to the sensitive error sources of the system,which are the position angle error of the mobile platform and the driving angle error of the three link manipulator joint.Then,the most widely used criteria of overturning stability are introduced.FAM criterion is selected as the stability criterion for the coordinated towing system of wheel mobile multi-robot.Then,according to the inverse kinematics of the manipulator,two groups of manipulator angle variables are solved.The stability of the system is analyzed by using FAM stability criteria under the three conditions of static,static and dynamic forces.Finally,the standard stability angle of the inverse kinematics solution of two groups of manipulator is compared in MATLAB software.The results show that the system is in stable state during the movement,and a set of variables,namely,the inverse solution,is more stable.The results provide the basis for further optimizing the trajectory planning and workspace of the system.Finally,in order to improve the anti overturning capability of the system,the design parameters of the wheel mobile manipulator are optimized.Based on the FAM stability criterion,the influence of the number,quality,diameter and installation position of the manipulator on the stability of the system is analyzed.