Gyroscope Control System Research Articles

The Analysis and Design of Closed-Loop Control System for MEMS Vibratory Gyroscopes

A digital closed-loop control system with all digital phase locked loop (ADPLL) is designed and optimized, in order to improve the bias stability and transient response of the gyroscope. The nonlinear mathematical models for the closed-loop amplitude and phase control system are established. The linearization method is applied to analyze the nonlinear models. The control parameters of the drive loop are optimized. The experimental results show that the phase deviation between the demodulation reference signal of the drive loop and the sense signal is less than 0.25° in the temperature range from-40°C to 60°C, within 0.15° of the variation. At room temperature, the overshoot amount of the gyroscope control system is 4.5% with setting time of 0.12s. The bias stability is 1.45°h. Compared to the analog control scheme, the digital control system has advantages of short setting time, small overshoot, short phase locked time, large locked range, high phase precision, etc.

Extended Kalman filtering based parameter estimation and drift compensation for a MEMS rate integrating gyroscope

This paper presents an offline extended Kalman filtering based parameter identification and drift compensation for a MEMS ring vibratory gyroscope. Damping and stiffness imperfections are the major error sources in MEMS vibratory gyroscopes. In the rate integrating operation mode, where angle is output instead of angular velocity as in the case of the rate gyroscope, parameter identification is an essential prerequisite for any feedback control and compensation algorithm to minimize angle drift and other errors. The proposed EKF method provides five estimates for the resonator DC loop gain, and another four parameters related to the non-proportional damping and aniso-elasticities. The method is based on the slowly varying averaged dynamic model expressed in terms of orbital elements. The averaging methodology offers important advantages over similar attempts based directly on the dynamic model expressed in terms of fast time varying displacement and velocity of vibration. Firstly, the observed measurements are subjected to significantly lower levels of noise as a consequence of the narrowband demodulation process employed in the calculation of the orbital elements. Secondly, the EKF requires much lower update rate due to the slowly varying nature of the augmented states. These advantages result in a more accurate estimation, improved stability performance and the possibility for real time implementation of the EKF. Numerical simulation and offline implementation of the EKF using experimental gyroscope operation data are provided to validate the proposed method. Moreover, the identified damping imperfections have been used in the drift compensation control in a DSP based real time rate integrating gyroscope control system. Ultimately, the maximum angular drift has been reduced to 1° per second. Spectrum analysis shows the angle drift error is dominated by 4th harmonics caused by dynamics not included in the conventional gyroscope model.

A digital signal processing-based control system for a micro-electromechanical systems vibrating gyroscope with parametric amplification and force rebalance control

This article reports a digital signal processing-based digital implementation of a micro-ring gyroscope control system that can be programmed to operate in open loop with parametric amplification or closed loop with force rebalance control according to bandwidth and dynamic range requirements. Parametric amplification is directly applied to the secondary mode and amplifies the Coriolis response by an order of magnitude. In order to improve the dynamic range and bandwidth performance of the gyroscope, force rebalance control loops are designed for the vibrations both in-phase and in quadrature with the Coriolis response. Experimental results show parametric amplification of the Coriolis response by a factor of 11 and correspond to an improvement in the signal-to-noise ratio by a factor of 9.5. The effectiveness of the force rebalance control is shown experimentally, and both the measurement bandwidth and the dynamic range have increased beyond the test capability of the rate table.

Applications of Fuzzy Sliding Mode Control for a Gyroscope System

The study proposed the application of the fuzzy sliding mode for a gyroscope system status control. The state response analysis of the gyroscope system revealed highly nonlinear and chaotic subharmonic motions of2Tduring state formation. The current study discussed the use of tracking control on the sliding mode control and fuzzy sliding mode control of a gyroscope control system. Consequently, the gyroscope system drives from chaotic motion to periodic motion. The numerical simulation results confirm that the proposed controller provides good system stability and convergence without chattering phenomena.

MEMS gyroscope control system using a band-pass continuous-time sigma-delta modulator

This paper presents a MEMS gyroscope control system of using a high-order band-pass continuous-time sigma-delta modulator. Compared with a low-pass discrete-time sigma-delta modulator based solution, the band-pass modulator can considerably decrease the sampling frequency; moreover, the continuous-time architecture has an obvious advantage on PCB prototyping and shorter lead time of the implementation in hardware. System level simulations using MATLAB/Simulink show the proposed sixth order sigma-delta modulator can achieve a high SNR of 100 dB for an angular rate input with an amplitude of 200°/s and a frequency of 32 Hz. A PCB circuit implementation is simulated using Orcad/PSpice to analyze the stability, and implemented in hardware. Measurement of the power spectral density of the output bitstream reveals a noise floor of −90 dBV/Hz1/2. The prototype is tested on a rate table with an angular rate input, verifying that the principle of the approach of using an electro-mechanical band-pass sigma-delta modulator control system for a MEMS gyroscope.

Design and real-time implementation of a multivariable gyro-mirror line-of-sight stabilization platform

Gyro-mirror line-of-sight stabilization platform is a nonlinear, multivariable and highly coupled system. It forms the basis of a wide range of practical instruments used for the purposes of sighting and targeting in both surface and airborne vehicles, which is capable of maintaining the sightline of a mirror when it is subjected to external disturbances. However, a spinning gyro has a property known as precession such that when a torque is applied to one axis, it will contrary to the intuition of mechanics, and results the rotation in the direction of another axis. This behavior poses a problem in controlling the line-of-sight since movement about one axis will cause a coupled movement in the other. In this paper, an efficient full-matrix fuzzy logic controller is designed and implemented for a practical nonlinear gyro-mirror line-of-sight stabilization platform. Both simulation and real-time experimental results demonstrate the effectiveness of the designed full-matrix fuzzy gyroscope control system, which offers an excellent closed-loop response for the transient and tracking performances, with significant reduction in the coupling effect against cross-axis interactions.