A boundary-curve-based discrete tracking differentiator with phase compensation and its application for intake...

Reliable pressure signal filtering and differentiation in high-altitude testing systems are challenging because of rapid signal variations, wide bandwidth, and strong measurement noise. This work proposes a boundary-curve-based discrete optimal tracking differentiator (TD) with phase compensation to improve pressure signal processing and control performance. A novel second-order discrete optimal control composite function (Fqr) is constructed using boundary and control characteristic curves, avoiding the complex square-root operations of the classical Han's TD (Fhan-TD). A prediction compensation scheme is further introduced to improve the phase quality of Fqr-TD. Simulation results under signal-to-noise ratios (SNRs) of 20-50 dB show that Fqr-TD reduces the tracking filtering error by about 25%-26% and the differentiation error by about 31%-32% compared with Fhan-TD. Experimental results show that the proposed TD-based active disturbance rejection control (ADRC) achieves a steady-state pressure error below 0.1 kPa, limits the maximum transient pressure fluctuation to 0.8 kPa, shortens the response time to 4.0 s, and reduces valve oscillation from ±5.0^∘ to within ±0.4^∘, demonstrating its effectiveness for intake pressure control in high-altitude testing systems.