The Research And Design Of Gyroscope Readout Circuit And Error Compensation Algorithm

Compared with other traditional gyroscopes,MEMS gyroscopes are small in size and light in weight.Due to their low cost and suitable for mass production,MEMS gyroscopes are widely used in daily life and have received widespread attention.For example,in an immersive game,with the help of a MEMS gyroscope,the player’s position,movement,and posture can be captured to enable the player to gain a better close personal touch.Analog readout circuits are used in traditional MEMS gyroscopes and they are normally realized by discrete analog components.The analog components will age and decay over time and will be easily affected by temperature change.This causes the analog component’s parameters to deviate from its original values and will affect the performance and even the functioning of gyroscopes.Besides,due to the limitation of the microfabrication technology,the drive axis and the sense axis of the gyroscope fabricated may not be orthogonal to each other,and this will result in cross-couplings of signals between the two axes causing serious measurement errors during the operation of the gyroscope,which leads to quadrature error.To solve the above problems,this dissertation proposes a digital gyroscope readout circuit with quadrature error compensation.Using digital readout circuits has the advantages of fixed codings,fixed parameters and fixed responses which will not be affected by temperature change and components aging problems faced by the analog readout circuits.To solve the cross-coupling of signals between the drive and sense axes,a digital I/Q demodulation method is employed to made a clean segregation of the quadrature error from the actual angular velocity measurement.Moreover,an improved PID controller is proposed to form a closed-loop control system to feedback the quadrature error information to the gyroscope sensing elements to correct the orthogonal misalignment.The MEMS gyroscope digital readout circuit with quadrature error compensation is simulated and verified using Modelsim and is realized on Xilinx FPGA.Experimental results show that a bias stability of 43.659~o/h and an output nonlinearity of 0.2333%are achieved.