| Currently,the gravity compensation systems are widely used in many fields,such as planetary vehicle ground walking,solar wing deployment,space manipulator movement,spacecraft docking,and so on.Through the gravity compensation system,ground experiments have been carried out to simulate the extraterrestrial working state of spacecraft,verify the feasibility of the design,and reduce economic losses.According to the characteristics of the lunar rover ground walking experiment,this paper analyzes the shortcomings of existing gravity compensation methods,proposes a gravity compensation system based on the principle of magnetic levitation,and carries out relevant research.The main work is as follows:Firstly,the design of the active and passive composite maglev gravity compensation system has been carried out.The design of the lunar rover walking simulation experiment is tailored to its requirements and functional division of the gravity compensation system are conducted.According to the linear superposition principle,the air gap magnetic field equation of the hybrid maglev electromagnet is established.The magnetic field performance of the hybrid maglev electromagnet is analyzed through the magnetic field simulation experiment.The cam profile equation of passive constant force component is established using energy balance method,and the output accuracy of passive constant force is analyzed by ADAMS simulation experiment.Secondly,a kinematics and dynamics modeling analysis of gravity compensation system is conducted.Based on D-H method and terrain coordinate method,the relationship between the lunar surface terrain input and the electromagnet air gap is established,and the reliability of the model is verified through the lunar rover ground walking simulation experiment.The dynamics model of the microgravity simulation system is analyzed,and the control decoupling of the system components is realized by simplifying the dynamics model.The interference force source of gravity compensation system is analyzed,and the interference force model is established,which is solved by combining the kinematics simulation results of the lunar rover.Thirdly,the stable suspension control of the magnetic suspension and the active constant force control system are designed and analyzed through simulation experiments.To meet the requirements of stable air gap control for the system,a hybrid electromagnet magnetic attraction model is established using the magnetic circuit analysis method and a dynamic modeling of the magnetic suspension servo assembly is built.Combining the loop voltage equation,a stable suspension control model is established,and feedback linearization is used to achieve decoupling control for multiple electromagnetic iron systems.Through simulation experiments,the operating performance of the control system is analyzed.The active constant force component control includes two parts:adjusting the motor angle control and the electric push rod constant force control.For the former,the motor position control model is established,while the latter uses the fuzzy PID algorithm to design the constant force controller.Then,the push rod constant force output is achieved through the hybrid control of force and position.The accuracy of the motor angle output and the tension output of push rod are analyzed through simulation experiments.Finally,the magnetic levitation system verification experiment is conducted.By comparing the experimental and calculated results of the magnetic attraction of electromagnets,the magnetic attraction model is modified.The feasibility of the stable levitation control system is verified through no-load and load magnetic levitation experiments,which provides a foundation for the subsequent construction of a complete gravity compensation system. |
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