Hardware Design And Implementation Of Gyrowheel System

The concept of gyrowheel originated from the need for attitude control of mircospacecrafts.The three most important indicators for evaluating a positive attitude control system applied to a mircospacecraft are its mass,volume,and accuracy for attitude control.Based on this,Canadian researchers have proposed a special gimbal structure,which can allow the rotor to tilt within a certain angle range freely in a radial direction.And this is just the gyrowheel.Three-axis control torque is generated,and meanwhile,two-axis attitude angular velocity of the spacecraft could be sensed by a gyrowheel.While maintaining the precise orientation of the attitude control system,the system size and weight as well as its development costs could be reduced.This paper will assist the gyrowheel system to realize its attitude detection and control from the perspective of hardware circuit design.Firstly,to guarantee the attitude control function,the gyrowheel should be controlled at a specified speed.Therefore,it is necessary to design and implement a flywheel drive circuit to acquire a stable speed accuracy.In the choice of schemes,a phase-locked loop control was used.Its negative feedback control based on a frequency and phase detector has great advantage on speed stability.The hardware circuit of the scheme was built,and each section of the circuit was modeled and converted to a transfer function.A serial lead correction controller was designed to ensure the stability margin of the system.Finally,the speed stability and regulation performance were verified by Simulink.Secondly,the Ether CAT slave station was designed and implemented as the communication part of the gyrowheel system in order that each module of the gyrowheel system could maintain real-time communication with the master station to facilitate unified monitoring and management.According to the OSI model,the Ether CAT slave circuit design was divided into physical layer,data link layer and application layer.Meanwhile,the interference of crosstalk,ground noise,rail collapse,and signal reflection on waveforms was briefly analyzed in terms of signal integrity.Optimization suggestions in the PCB layout were given.From the perspective of Ether CAT slave software design,a slave device microprocessor was used to build an application layer protocol programming platform for the Ether CAT state control and process data communication.Twin CAT3 was used as the master station,and Wireshark was utilized for packet capture to analyze the performance and reliability of this communication system.Finally,in order to ensure the accuracy of the attitude calculation system,a highly accurate current measurement circuit based on resistor sampling scheme and an improved I/F conversion scheme was designed and implemented.Error sources of the two schemes were analyzed quantitatively,and the components were selected in a targeted manner.Then,hardware compensation was applied as much as possible.In experimental stage,the process of data fitting and accuracy testing were introduced in detail,and the test results of the two schemes were given.Finally,Fourier analysis was used to guess the source of the harmonics in the test results,and the two current measurement schemes were compared in several aspects.