Modeling And Cooperative Compliance Control Of Tightly Coupled Multi-arm Robot System

Multi-robot collaboration is an important means to complete complex tasks and has become a research hotspot in recent years.However,most of the current considerations are loosely coupled scenarios,that is,each robot arm completes its own work independently according to a set time sequence,without considering the movement of other robot arms,and it is difficult to ensure the overall work efficiency and execution effect.In order to effectively improve the performance of complex tasks,it is necessary to consider multiple robotic arms as a tightly coupled system to achieve real-time interaction and intelligent collaboration.Based on this,this paper carried out the research on the kinematic modeling of the multi-arm tightly coupled system,the collaborative compliance control method,and developed the lightweight cooperative manipulator,established the experimental platform,and carried out the experimental verification of typical tasks.Combined with the actual task scenario,the kinematics and operating force model of the tightly coupled system formed when multiple arms are operating on the same target are established,and a collaborative operation trajectory planning method is proposed for typical grinding tasks.Taking the world coordinate system as a reference,the relationship between the multi-arm tightly coupled system and each single arm is deduced,and the desired force of the workpiece is distributed to the corresponding mechanical arm using the minimum norm method.Furthermore,the process characteristics of the grinding operation are analyzed,and the multi-arm coordinated motion trajectory is planned based on this,including the initial section,the process section,and the return section,so that the multi-arm planning and the process planning are independent of each other.In order to achieve constant force tracking under unknown environmental parameters,an integral adaptive admittance control method is proposed.The control law is expressed as a third-order linear system equation,the operating environment is equivalent to a spring model,the control error transfer function is derived,and the control performance under the step response is further analyzed.The simulation result shows the proposed integral adaptive admittance control The method has better performance than traditional methods,there is no steady-state error,and overcomes the difficulties caused by nonlinear discrete compensation,and can facilitate analysis in the frequency domain,realize parameter optimization and improve calculation accuracy.Furthermore,the proposed collaborative trajectory planning and compliance control methods were written into software,and a multi-arm collaborative control system based on ROS was developed,which has the communication compatibility of Ether CAT,CANopen,and TCP\IP,and can simultaneously control 3 robotic arms.Through the separation of upper and lower computers,the versatility of the upper computer is realized,and it can be switched between the physical object and the Gazebo simulation platform at will,and the "zero" migration workload of simulation and physical control is realized.The software uses Py Qt to write a visual interface to realize visual operations,real-time data display and other functions.At the same time,a three-arm physical simulation environment is built in Gazebo to realize physical simulation and virtual display functions.Finally,a light-weight collaborative robotic arm was developed and a three-arm collaborative experiment system was established,and key algorithm verification and multi-arm collaborative simulation polishing experiments were carried out.The verified robotic arm has a dead weight of 9.5kg and a load of 2kg.It adopts the Ether CAT communication protocol.It forms a three-arm experimental scene with three communication protocols with the UR5 robotic arm using TCP\IP communication and the self-made CANopen communication protocol.Complete the equivalent stiffness evaluation experiment,the integral adaptive admittance control experiment,the two-arm handling experiment,and the three-arm collaborative simulation polishing experiment.The experiment shows the effectiveness of the multi-arm tightly coupled system model,multi-arm planning algorithm,and integral adaptive admittance control method.