CONTROL UNIT OF TEST BENCH FOR ELECTROMAGNETIC ORIENTATION AND STABILIZATION OF SPACECRAFT
The control unit and methodical support of the test bench are offered. The task of the stand is to simulate the change of the Earth's magnetic field during the movement of the spacecraft in orbit to test the algorithms of the angular orientation system and stabilize the spacecraft. The article presents a model of the Earth's magnetic field, as well as the matrix of the transition to the oscillating coordinate system. The article describes the calculation of control currents to maintain the required number of ampere-turns, the control algorithm includes 2 PID controllers, and describes the block diagram of the control unit. The control unit has overcurrent and voltage protection, as well as short-circuit protection. To increase the accuracy of maintaining the desired magnetic field strength, an algorithm is implemented that uses current sensors and a three-axis magnetometer, which is installed in the center of the Helmholtz ring system. For management the standard USB interface, for connection to the personal computer is implemented. The output stages of the control unit are implemented according to the H-bridge scheme. The control unit has six independent control channels that have the same technical characteristics. The software interface numerically and graphically shows the magnitude of the magnetic field along three axes. The interface also shows the amount of current in the coils and the correction factors of the PID controller, as well as the input values of the field strength of the model of the Earth's magnetic field, which can be downloaded into the program by clicking "download model". The software allows you to control the control unit in manual and automatic mode, using the model of the Earth's magnetic field, thereby simulating the magnetic field given the nature of the spacecraft, which allows you to more accurately determine the characteristics of angular orientation and stabilization.
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