The Compliant Control Of Robonaut Based On Detection Of The Unknown Disturbance Force

With the rapid development of space industry of our country,single-arm space robot can't fully satisfy the requirements of space tasks.Serving as a kind of space agency possessing outstanding coordination ability,Robonaut plays a more and more important role in the execution of many space tasks such as carrying equipment and replacing moment gyroscope.However,because of the complexity and changeability of the space environment,the interference between Robonaut and human astronaut/working environment will appear unavoidably during Robonaut's execution of space operation tasks.If the disturbance force can't be detected and controlled,not only the task requirements of Robonaut's running accuracy can't be satisfied,but also the Robonaut and the space facilities will be damaged.Therefore,it is theoretical and practical to study the disturbing force detection and compliant control for Robonaut.This research comes from the National Natural Science Foundation of China named "Stability control strategy for space manipulator system in on-orbit self-assembly task when carrying a heavy payload"(61573066).In this paper,some key technologies including the dynamic modeling method,compliant control strategy,coordinated operation control strategy and disturbing force detection of Robonaut are studied.The main research includes:The compliant control method of manipulator with known disturbing force is studied at first.Aiming at the problem that the traditional dynamic model contains limited information,the null-space of Jacobian matrix is introduced to establish the extended dynamic model of manipulator.The combination of the manipulation space and null-space dynamic equation is realized,which builds the foundation for the disturbing force control based on the extended dynamic model.Aiming at the problem of disturbance force control,the manipulation space impedance control method is studied based on the extended dynamic model of manipulator,and combining with the null-space impedance control algorithm,the impedance control algorithm of manipulator with the known disturbing force is designed.The disturbance force control is carried out while the compliant control of the end of manipulator is realized,so as to reduce the adverse effects of disturbance force on the manipulator system.Then,the coordinated operation compliant control of Robonaut considering the effect of disturbing force is given.The object of the study is extended from the single-arm robot to Robonaut,on the basis of null-space of Jacobian matrix,the Robonaut's dynamic equation is extended.Aiming at the problem of the coordinated operation compliant control of Robonaut,the geometric constraints and mechanical constraints of the ends of both arms and the operation object are analyzed,a unified dynamics model of Robonaut and operation object is established,and based on which the coordinated operation compliant control strategy satisfying the impedance of operation object is given to realize the disturbance force control while accomplishing the position and posture tracking and internal force compliance control of operation object.After that,aiming at the problems that contacting point and size of disturbing force are unknown,the coordinated operation compliant control method of Robonaut on the basis of disturbance observer is studied.Aiming at the problem that disturbing force cannot be directly acquired,based on the conservation of generalized momentum,and the disturbance observer of manipulator is designed to observe disturbing torque and equivalent disturbing force.The object of study is extended from the manipulator to the Robonaut.On the basis of the derivation of the disturbance observer of the coordinated operating system,an impedance control strategy based on a disturbance sensor is designed.The strategy can realize the control precision of the position and internal force of the operation object under the unknown disturbance force,improve the ability of anti-interference and enhance adaptability under unknown disturbing force.Finally,the experiments of the coordinated operation compliant control strategy of Robonaut are discussed.Reconstructing the ground experimental platform of Robonaut,the coordinated operation impedance control of manipulator and Robonaut considering the effect of disturbing force is designed;the effectiveness and practicability of the proposed algorithms are verified by analyzing experimental data.