Research On Capacitive Absolute Coded Angular Displacement Sensor

Ultra-high-automated production has become more and more demanding for integration,miniaturization,and high-precision of sensors.Capacitance angular displacement sensors are not only simple in structure,but also capable of achieving high resolution,high precision,high stability,and easy integration.Therefore,it is widely used in various types of precision detection systems and is considered to be the most promising sensor.However,the parasitic capacitance and electric field edge effect of the capacitance angular displacement sensor seriously affect the linearity and measurement accuracy of the signal.The traditional solving circuit is complicated,the electronic subdivision program is difficult and the response speed is slow.Most domestic scholars in dealing with this issue,always from the model optimization,sub-divisional aspects.While it was certain precision performance,but increase the overall efficiency of the processor,increasing processor power and solver time.In the high-speed solution system,it is not easy to take.Therefore,this paper designs a capacitive absolute angular displacement sensor for the defects of the capacitance angular displacement sensor,which is of great significance to the development of the capacitive sensor.This paper based on the working principle of the rotary transformer,and established the theoretical mathematical model to invent a capacitive absolute angular displacement sensor with amplitude modulation and tracking closed loop.The mechanical structure proposes three-layer plate distribution,and the transmitting electrode and the receiving electrode are distributed on two fixed plates to receive the stable signal.In order to reduce the size of the sensor,the reflective plate is not used,and the moving plate adopts a sine-cosine shape to make the output signal have good sinusoidality.Through the Maxwell electromagnetic simulation,the optimal design parameters of the capacitive absolute angular displacement sensor are obtained.In order to reduce the complexity of the solving circuit,the rough machine solving signal and the fine machine solving signal are proposed to pass through the switch strobe chip.The circuit realizes the spectral separation of coarse,fine fundamental and high-frequency signals by sharing a set of detection.The signal subdivision uses a combination of positive and negative cut subdivision and quadruple frequency subdivision,and uses the cursor subdivision principle to subdivide the signal twice,cleverly avoiding complex electronic subdivision circuits to get the higher accuracy measurement and resolution.The digital circuit uses a programmable logic device CPLD and a digital signal processor DSP dual processor to achieve high efficiency calculation speed.