Search

Double-coil inductive displacement transducer is a noncontact-type high-precision displacement measurement element, which is widely used in industrial manufacturing and large power equipment systems. Since the inductive displacement transducer has a parasitic capacitance, the frequency of the excitation signal has a great influence on the performance that has been little studied so far. In this article, the method of determining the optimal excitation frequency of double-coil inductive displacement transducer is studied. The working principle and characteristics were analyzed, a signal conditioning circuit was proposed, and a circuit simulation model was established. According to the simulation results, the influence law of the frequency of excitation signal on the double-coil inductive displacement transducer is obtained. The effect of frequency on the displacement transducer was analyzed in five aspects: frequency characteristics, output signal, sensitivity, the residual voltage at zero, and linearity. Finally, the effectiveness of the simulation results was verified through experiments. The simulation and experiment show that the proposed signal conditioning circuit can realize the demodulation of the double-coil inductive displacement transducer signal. Taking DIPT14 displacement transducer as the research object, the frequency of excitation signal has influence on the sensitivity, residual voltage at zero, and linearity. When the frequency is low, the parasitic parameters have little effect on the performance of the transducer and can be ignored. However, when the frequency is high, the parasitic parameter has a great influence on the performance of the transducer. The method presented in this article is of great significance for the study of the characteristics, signal conditioning circuit, and the determination of the optimal frequency of the excitation source of double-coil inductive displacement transducers.

Pilot-operated electro-hydraulic proportional directional valve is a key hydraulic component to control the motion of large power equipment such as construction machinery and agricultural equipment. The control accuracy and response speed of the valve control element are very important to the performance of the hydraulic system. In this paper, control strategies for dead-zone control and valve control systems are reviewed. In order to eliminate the dead-zone of pilot-operated proportional valve control, the current control schemes for dead-zone detection and dead-zone compensation are summarized, and the control schemes are evaluated. The proportional–integral–derivative-related control, nonlinear control, and robust control of the pilot-operated electro-hydraulic proportional directional valve control system are reviewed, the relationship between the control strategies is analyzed, and the different control algorithms are evaluated. The shortcomings of the research program are analyzed, and the corresponding solutions are proposed. Based on the current research, future research progresses for eliminating the control dead-zone and optimizing control strategies are presented.