Research On 2D-Tracking Control Of Low-Gravity Simulation System Of Mars Rovers

With the rapid developing of China's space technology,the spacecraft is more and more complex and expensive,however there exists strictly launch window on outer space exploration,leading to the reliability of spacecraft requires very high,this complex features constitute a contradiction with the spacecraft.So,in order to ensure the success of space missions,it's necessary to continuously improve the reliability of spacecraft.Therefore it's necessary to test low gravity simulation experiment on the ground,because the low gravity test can simulate the working state of the spacecraft in space,to verify the functionality and reliability of spacecraft.By comparing the current low-gravity test methods on the ground,the active suspension method has the strongest adaptability and can meet the requirements of low-gravity test of various types of spacecraft.This paper mainly aims at the problem that the sling needs to keep the lead hammer's follow-up control all the time during the 2-d follow-up of the active suspension method,and the problem that a single sensor of the pose measurement system cannot meet the task requirements.The research was carried out in three aspects: 2-D servo modeling of the active suspension method,the multi-sensor data fusion of the pose measurement system and the 2-D tracking control.The content is as follows:In term of 2-D servo modeling,the mechanical design of 2-d servo system is firstly completed,and the rigidity is checked,then the dynamic model of the servo system is established by Lagrange equation,and the model is simplified based on Taylor expansion near the working point.And then through the analysis of the symmetry and decoupling of simplified model to simplify the model further,get the final simplified model.Finally the validity of the model is verified by simulation.In the aspect of multi-sensor data fusion,the distributed framework of data fusion is first established,the pre-processing filtering algorithm and the fusion algorithm of fusion center are designed,and the multi-sensor data fusion algorithm is obtained.In order to avoid the pollution of the outlier to the fusion data,a dynamic threshold judgment and the algorithm of removing the outlier are designed by setting the deviation degree.Then the algorithm is verified by simulation to judge the outlier and the fusion precision.In terms of 2-D tracking control,first of all the 2-D mathematical model of servo system is completed based on 2-D servo motor,drive and transmission mechanism modeling and combined with the simplified model of the front.Secondly,the two-stage control strategy of the crane follow-up and 2-D platform compensation is determined.Then,the controller is designed using the three-loop control method of current loop,velocity loop and position loop,and the effectiveness of the controller is verified by simulation.And since the crown need to adapt to control the requirements of speed of different size,it's need to crown fuzzy PID controller for improving design,and improve the effectiveness of the controller design is validated by simulation.By servo control design improvements and multi-sensor data fusion,can effectively improve servo control precision and the reliability of the pose measurement system,at last,through the whole physical platform test technical indicators meet the system requirements.