Development and testing of a digital drive system for a vibrating tube densimeter with dual parallel straight measuring tubes

To address safety risks from delayed offline cement slurry density detection in cementing and defects of traditional U-tube Vibrating Tube Densimeters (VTDs), this study developed a digital closed-loop drive system for a dual parallel straight-tube VTD suitable for high-pressure/high-solid-content conditions. A "driver-vibrating tube-sensor" dynamic model was established to clarify resonant state’s role in accuracy; a composite algorithm was proposed—adaptive frequency sweeping in start-up locked resonant frequency and hardware lag phase, while PID-based closed-loop offset digital delay and stabilized amplitude. Tested on a TI-TMS320F28335 DSP platform with 6 media, results showed: closed-loop phase difference fluctuation≤±0.1° (response time≤1s), vibration amplitude error≤±0.002V, and density measurement error ≤±0.002 g/cm³, which meets on-line cement slurry density measurement needs for cementing.