Research On Coordinated Operation Strategy Of Redundant Dual-arm Robot

The redundant dual-arm robot is one of the new issues in robots study in nowadays.With the constant aggravation of the disadvantage of single-arm robot on operation function,control,and etc,the redundant dual-arm robot with the coordinated operation capability attracts much attention.The control and analysis of the redundant dual-arm robot is a complicated and difficult subject due to the constrains between the two manipulators.This paper systematically studies the kinematics and dynamics problems of the redundant dual-arm robot for coordinated operation.The main content of this thesis include five aspects:(1)To deal with the obstacle avoidance problem of redundant robot,an obstacle avoidance algorithm based on transition between the primary and the secondary tasks is presented.Firstly,the obstacle avoiding motion is defined in one dimensional operational space,and two transition variables are used to make a smooth and continuous priority transition between the trajectory tracking motion and the obstacle avoiding motion of the end-effector using the real-time minimum distance.Finally,the validity of the algorithm is manifested by simulations of several redundant robots.As a conclusion,the redundant robots can not only realize the obstacle avoidance,but also prevents the conflict between tasks by the proposed approach.(2)The coordinated motion tasks of the redundant dual-arm robot is studied.This allows a straightforward description of general coordinated motion tasks in terms of meaningful absolute and relative variables.The task Jacobians are expressed in terms of the Jacobians of the single manipulators.Based on this,the kinematics inverse solution of redundant dual-arm robot used to realize coordinated operation is obtained.Moreover,combined with the obstacle avoidance algorithm of redundant single-arm robot,an obstacle avoidance algorithm for the redundant dual-arm robot is presented.Using this approach,the robot can accomplish the coordinated motion tasks while avoiding the obstacles.(3)To deal with the problem of inverse dynamics modelling for Multi-DOF robot,a recursive inverse dynamics modelling method based on decoupled natural orthogonal complement is presented.In this model,the concepts and methods of Decoupled Natural Orthogonal Complement matrices are used to eliminate the constraint forces in the Newton-Euler kinematic equations,and the screws is used to express the kinematic and dynamics variables.On this basis,the paper has developed a special simulation program with symbol software of Mathematica and conducted a simulation research on the a 7-DOF serial robot and a opened-chain redundant dual-arm robot.Simulation results show that the proposed method based on decoupled natural orthogonal complement can save an enormous amount of CPU time that was spent in computing compared with the the software of ADAMS and the results is correct and reasonable,which can verify the reliability and efficiency of the method.(4)The dynamics of the closed chain formed by the redundant dual-arm robot and the object is studied.The issues of load distribution and dynamic optimal is analysed.Using the kinematical constraint,the method of nonsqeezing dynamic loads distribution for the closed chain formed is proposed.This method can separate the motion-inducing from the squeeze-inducing effects for a given end effector force solution vector.Furthermore,an optimization method of the torques acting at the joints is proposed by using the advantage of redundancy.(5)Based on three-dimentional model,a virtual prototype of the redundant dual-arm robot is built using ADAMS software.For coordinated transportation and assemble operation,task decomposition and allocation involved in the coordinated operation is studied with theoretical analysis and numerical simulation.This will provides reference for design and operating of a virtual prototype.This dissertation's research on obstacle avoidance,coordinated operation,dynamics modelling,load distribution and dynamic optimal,task decomposition and allocation covers the major issues related to the realize coordinated task of the redundant dual-arm robot.It could not only be used for provide support for coordinated control of the redundant dual-arm robot,but could also have great reference value in researching on many other complication robot such as multi-arm robot,multi-legged robot,etc.