Research On Reconfigurable Robots Handling Flexible Objects Under Different Constraints

Although robotics has been widely applied in various fields,but the traditional robot has the characteristics of high cost,low speed,low accuracy,single function,weak environmental adaptability,long development cycle and so on,which can not meet the needs of " Industry 4.0" and "Intelligent Manufacturing".Reconfigurable robots,which are not limited by environment,task constraints,variable configurations,low cost and easy to manufacture,emerge as the times require.Reconfigurable robots and their related researches are of great importance.Based on this,this paper will study some meaningful topics about the reconfigurable robots handling the flexible loads under different constraints.The kinematics and dynamics of the reconfigurable robots,the flexible loads and the reconfigurable robots flexible handling the flexible loads systems are analyzed.The dynamic characteristics of the system are analyzed by numerical simulation.The main contents of this paper are as follows:Firstly,based on the Screw Theory,the mathematical modeling of general robot is discussed.The kinematic model of robot is established by means of the exponential product(POE)formula.On the basis of the kinematic model,the rigid dynamic model of the robot is established by combining the Lagrange-Euler equation.The EV-MRobot series modularized reconfigurable robot is taken as the research object,and the kinematics and dynamic modeling method of the reconfigurable robot is preliminarily studied.An automatic kinematic modeling method based on features and connections was proposed.Based on this,automatic generation of dynamic models was also achieved.Secondly,taking the general elastic beam as the research object of the flexible load,the kinematic model of the flexible load is established by using the theory of deformation spinors.Based on the Lagrange-Euler equation,the flexible dynamic model of the load is established.According to the interaction between the flexible load and the robot end effector and the special relationship between the force/torque of the robot joint and the external binding force,the system coupling dynamic model is established through the Velocity Jacobi Matrix.Then,the motion model of the system is deduced according to the different mechanical,environmental and geometric constraints of the flexible load and the environmental constraints and the actuator end-effector.Given the operating conditions of the manipulator and the environmental constraints,the inverse kinematics model of the system is deduced.Given the joint driving torque of the manipulator and the desired trajectory at the load end,the forward kinematics model is deduced.Finally,the numerical simulation of a three degree of freedom(DOF)reconfigurable robot operating the flexible beam is performed.The simulation results show that this method is effective.At the same time,it is shown that under different binding conditions,the dynamic characteristics of robots will change dramatically,which is not only related to the magnitude of binding variation but also to the frequency of binding variation.When the binding frequency is constant,the larger the amplitude is,the greater the amplitude of the driving torque is.The amplitude of the binding force is constant.The driving torque variation cycle varies with the frequency,but the magnitude of the change is related to the configuration and the current pose of the robot.It can also be seen that the change of the mechanical properties of the robot will be different when the binding force is constant and the configuration of the robot is different,which is of great significance for the design and selection of the robot configuration in practical applications.