A study on the application of MEMS accelerometers and gyroscopes in fast steering mirror control systems

A study on the application of MEMS accelerometers and gyroscopes in fast steering mirror control systems

Hojjatollah Moghaddasi1

1) Master s degree in electrical engineering and precision components, Faculty of Electrical Engineering, Malik Ashtar University of Technology, Tehran, Tehran, Iran.

Publication : 7th International Conference on Applied Researches in Science & Engineering (7carse.com)
Abstract :
Fast Steering Mirror Systems provide two-axis, high-bandwidth rotation with sub-microradian resolution in a standard, economically viable design for commercial use in applications such as laser beam stabilization, laser pointing, tracking, and image stabilization. A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a major technology used in digital imaging. In a CCD image sensor, pixels are represented by p-doped metal–oxide–semiconductor (MOS) capacitors. These MOS capacitors, the basic building blocks of a CCD, are biased above the threshold for inversion when image acquisition begins, allowing the conversion of incoming photons into electron charges at the semiconductor-oxide interface; the CCD is then used to read out these charges. In a charge-coupled device (CCD)-based fast steering mirror (FSM) tracking control system, high control bandwidth is the most effective way to enhance the closed-loop performance. However, the control system usually suffers a great deal from mechanical resonances and time delays induced by the low sampling rate of CCDs. To meet the requirements of high precision and load restriction, fiber-optic gyroscopes (FOGs) are usually used in traditional FSM tracking control systems. In recent years, the MEMS accelerometer and gyroscope are becoming smaller and lighter and their performance have improved gradually, so that they can be used in a fast steering mirror (FSM) to realize the stabilization of the line-of-sight (LOS) of the control system. Therefore, a tentative approach to implement a CCD-based FSM tracking control system, which uses MEMS accelerometers and gyroscopes as feedback components and contains an acceleration loop, a velocity loop and a position loop, is proposed. The disturbance suppression of the proposed method is the product of the error attenuation of the acceleration loop, the velocity loop and the position loop.
Keywords : MEMS gyroscope; acceleration feedback control; multi-loop control; light of sight stabilization.