Dynamic Modeling And Parameter Identification Of Space Robot

With the development of science and technology,the amount of activities in exploring the space has drastically increased.It's obvious that the space robot plays a vital role in these activities,because it can replace human beings in conducting space missions like doing experiments in and outside capsules orbiting in the space,where circumstances are complex and adverse.The space robot is a typical model of multi-body system composed of multiple arms.There is joint friction and clearance between each hinge and these factors affect the dynamic characteristics of the space robot system.On the other hand,there is energy consumption when the space robot performs a task and this case will bring some change to the inertial parameters.The capture object should also be identified as its parameters are unknown.Above all,the significance of studying the dynamics and parameter identification of the space robot,both theoretically and technically,has been maintained.This dissertation is funded by Natural Science Foundation of China(11132001,11272202 and 11472171),the Key Scientific Project of Shanghai Municipal Education Commission(14ZZ021)and the Natural Science Foundation of Shanghai(14ZR1421000),and presents theoretical and simulation studies of the dynamic modeling and identification of the space robot.The main research and achievements are as follows:(1)This dissertation starts theoretical and numerical studies of dynamics modeling of the space robot system.First of all,the structures of the space robot are presented and the equivalent physical and mathematical models are established.Using the independent generalized coordinates to describe the multi-rigid-body system of the space robot,the dynamics equation of the system is then derived in details.Afterwards,the contribution of the joint friction to the dynamics equation is described and its format is given in details.Finally,numerical simulations verify the validity of the theory in this paper.Simulation results show that the dynamics model of the multi-rigid-body system established in this paper can effectively describe the space robot system features and lay a theoretical foundation for the identification work in the following chapters.(2)This dissertation presents studies of identification of the space robot based on the Newton-Euler equation.First of all,the background and operating principle of the six-dimensional wrist sensors are introduced.Then the Newton-Euler equation of the space robot concerning joint friction is presented and the parameters to be identified are separated from the origin equation.Afterwards,the parameters are identified based on the signal from sensors and the Newton-Euler equation.Finally,numerical simulations verify the validity of the theory in this paper.Simulation results show that the parameters of different part on the space robot can be effectively identified concerning joint friction.(3)This dissertation presents studies of identification of the space robot based on momentum conservation.Firstly,the format of linear momentum and angular momentum of the space robot system is given in details and the parameters to be identified are separated from the momentum equation.Then,the identification method of the hub,the capture object and both of them two is given.Finally,numerical simulations verify the validity of the theory in this paper.The simulation results show that the hub and the capture object can be identified at the same time based on momentum conservation.