Multi-master Multi-robot Teleoperation Control For Cooperative Manipulation

Teleoperation is a kind of technology to help people realize perception and behavior extension at the remote side by information technology through the long distance span between human and human and robot synchronous interaction.The technique has been widely used in deep seas,deep space exploration,and nuclear waste disposal.With the gradual complication of the operation task,single-operator single-robot(SOSR)technique is far from meeting the task requirements.This is limited by the operator's ability and the operation ability of the single robot.Therefore,the multi-operator multi-robot(MOMR)teleoperation is a curial for solving such problems.Comparing with the SOSR mode,the difficulties for MOMR teleoperation are shown from the following three aspects.First,the control mode and structure are limited by the constrains of multiple-robot cooperative tasks.Second,the networks environment consisted of communication between the slaves and masters and the local one in the slave or master side is more complex.Third,the cooperation and robustness of the cooperative actions should be considered except for the stability and transparency properties.Based on the previous studies,this paper studies the motion synchronization and cooperative control problems for the previous problems.The main results are presented as follows:In chapter 3,for the cooperative manipulation of multiple robot arms under the varying time delays,we consider the influence the uncertain dynamics and unknown outer force and propose an adaptive fuzzy control method based on state prediction.The method contains a new kind of control structure based on a position/force bi-observer.The position observer estimates the position states of the remote side under stochastic network-induced delays and reduces the influence of the time delay.The force observer is built based on the time-delay estimation(TDE)and the observer-gain-based method,which can reduce the computational complexity and estimate the coupled contact forces and dynamic uncertainties.The adaptive fuzzy control strategy is used to evaluate and suppress the uncertainty.Especially,compared with the existing approaches,the new controller improves the motion synchronization effect for the master-slave cooperative manipulations.Chapter 4 studies the uncertain ranges of the varying time delays caused by the multiple communication loop between the master and slaves.Considering the large estimation errors caused by the model and acceleration errors of the robot arms,a motion synchronization method based on the Takagi–Sugeno(T-S)fuzzy observer and modified hybrid TDE/observer-gain-based method is proposed.Based on the general bi-observers controller structure,the T-S fuzzy observer is used to estimate delayed remote state with low sampling rates and the improved force observer compensates the torque estimation errors timely by building an auxiliary model.The simulation results show that the torque estimation accuracy is improved by the proposed method,which is the first-proposed control scheme for the multiple-loop communication property of the MOMR teleoperation system.Chapter 5 investigates sudden changes of the internal force caused by distribution of the robot arms in MOMR teleoperation system and proposes the cooperative control method based on the relative position/force.Two strategies are proposed for balancing the motion synchronization and the cooperative control.The former divides robot arms as a dominant arm and a nondominant one.The dominant robot tracks the corresponding master's motions and the nondominant realizes the cooperative actions based on the relative Jacobian matrix.The latter strategy provides a new kind relative-impedance-based hybrid force/position control method.Two methods are adopted for reducing the internal force and motion tracking errors.One is designing an adaptive factor to switch authorities for position control and internal force control.The other is proposing a force estimating method to the coupled item of uncertain dynamics,disturbance and internal forces.Different parts of the coupled item are divided and solved separately by the nonlinear characters.Lastly,several simulations are taken for certifying the effectiveness of two control strategies.Chapter 6 studies the fast stabilization control method for multiple robot arms and object under the condition of object disturbance in MOMR teleoperation system.A control method based on the object-state observer and improved barrier Lyapunov functions(BLF)method.Considering the unmeasurable object deformation and unknown distance between the contact point and the object center,the control force is decomposed by the object state and manipulation effect,based on the analysis of the force/position coupling relationship between the multi-robots and the operating target.Under the constrains of the physical and performance during the operation process,we design a hybrid position/force control mode based on the nonlinear observer for object state and improved BLF method for ensuring the transient and steady position tracking performances.A Lyapunov function is built to prove the asymptotic convergence and the predetermined synchronization performance of the teleoperation system.Several comparable simulations are executed and results show that the continuing negative effect of disturbing force affecting on object is eliminated rapidly and all slave robots track master motions with similar contact forces.