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. 2016 Oct 20;16(10):1747.
doi: 10.3390/s16101747.

Decoupling Control of Micromachined Spinning-Rotor Gyroscope with Electrostatic Suspension

Boqian Sun  1 , Shunyue Wang  2 , Haixia Li  3 , Xiaoxia He  4
Affiliations

Decoupling Control of Micromachined Spinning-Rotor Gyroscope with Electrostatic Suspension

Boqian Sun et al. Sensors (Basel). .

Abstract

A micromachined gyroscope in which a high-speed spinning rotor is suspended electrostatically in a vacuum cavity usually functions as a dual-axis angular rate sensor. An inherent coupling error between the two sensing axes exists owing to the angular motion of the spinning rotor being controlled by a torque-rebalance loop. In this paper, a decoupling compensation method is proposed and investigated experimentally based on an electrostatically suspended micromachined gyroscope. In order to eliminate the negative spring effect inherent in the gyroscope dynamics, a stiffness compensation scheme was utilized in design of the decoupled rebalance loop to ensure loop stability and increase suspension stiffness. The experimental results show an overall stiffness increase of 30.3% after compensation. A decoupling method comprised of inner- and outer-loop decoupling compensators is proposed to minimize the cross-axis coupling error. The inner-loop decoupling compensator aims to attenuate the angular position coupling. The experimental frequency response shows a position coupling attenuation by 14.36 dB at 1 Hz. Moreover, the cross-axis coupling between the two angular rate output signals can be attenuated theoretically from -56.2 dB down to -102 dB by further appending the outer-loop decoupling compensator. The proposed dual-loop decoupling compensation algorithm could be applied to other dual-axis spinning-rotor gyroscopes with various suspension solutions.

Keywords: decoupling control; electrostatic suspension; gyroscope rebalance loop; inner-loop decoupling compensator; micromachined spinning-rotor gyroscope; outer-loop decoupling compensator; stiffness compensation.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Micromachined dual-axis spinning-rotor gyroscopes (MESG): (a) the exploded view of the device and (b) a fabricated device.
Figure 2
Figure 2
Block diagram of the rebalance loop without decoupling compensation.
Figure 3
Figure 3
Block diagram of the rebalance loop with full decoupling compensation.
Figure 4
Figure 4
Comparison of the cross-axis frequency responses with and without decoupling compensation. The calculation of 20 lg(Vx/φ˙x), 20 lg(Vdx/φ˙x), and 20 lg(Vox/φ˙x) are based on Figure 2 and Figure 3.
Figure 5
Figure 5
Block diagram of the rebalance loop in verification of the inner-loop decoupling compensation.
Figure 6
Figure 6
Simulated coupling error of the angular position that can be attenuated by the inner loop decoupling D(s) (denoted by I2) compared with the rebalance loop without decoupling (I1).
Figure 7
Figure 7
Block diagram of the rebalance loop in verification of the outer loop decoupling compensation.
Figure 8
Figure 8
Simulated cross-axis coupling of the gyroscope output responses with (O2) and without (O1) the outer loop decoupling compensator.
Figure 9
Figure 9
The MESG setup to test the decoupling compensation performance of the gyro rebalance loop.
Figure 10
Figure 10
Close-loop frequency responses with different stiffness compensations.
Figure 11
Figure 11
Experimental results of the suspension stiffness, which is improved by 30.3% with proper compensation.
Figure 12
Figure 12
Experimental results with the inner-loop compensation. The angular position coupling is reduced by 14.36 dB at 1 Hz and 8.58 dB at 10 Hz.
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