Analysis and Correction of Measurement Error of Spherical Capacitive Sensor Caused by Assembly Error of the Inner Frame in the Aeronautical Optoelectronic Pod

• Published in: Sensors (Basel, Switzerland) Vol. 22; no. 23; p. 9543
• Main Authors: Ma, Tianxiang, Yang, Shengqi, Xu, Yongsen, Liu, Dachuan, Hou, Jinghua, Liu, Yunqing
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 06.12.2022; MDPI
• Subjects: 2-DOF angular displacement measurement; Accuracy; Aeronautics; Analysis; Ball joints; Degrees of freedom; Electrodes; Error analysis; Error correction; four-quadrant differential structure; installation error compensation; Magnetic fields; Mathematical models; Measurement; Measuring instruments; Methods; Optoelectronics; Optoelectronics industry; Photoelectricity; Response time; Sensors; spherical capacitive angular sensor; spherical capacitive angular sensor; four-quadrant differential structure; installation error compensation; 2-DOF angular displacement measurement
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s22239543

The ball joint is a multi-degree-of-freedom transmission pair, if it can replace the inner frame in the aviation photoelectric pod to carry the optical load, which will greatly simplify the system structure of the photoelectric pod and reduce the space occupied by the inner frame. However, installation errors in ball joint siting introduce nonlinear errors that are difficult to correct and two degree of freedom angular displacement of the ball joint is difficult to detect, which limits application in the precision control of two degrees of freedom systems. Studies of spherical capacitive sensors to date have not tested sensors for use in an inner frame stabilisation mechanism nor have they analysed the influence of installation error on sensor output. A two-axis angular experimental device was designed to measure the performance of a ball joint capacitive sensor in a frame stabilisation mechanism in an aeronautical optoelectronic pod, and a mathematical model to compensate for ball joint capacitive sensor installation error was created and tested. The experimental results show that the resolution of the capacitive sensor was 0.02° in the operating range ±4°, the repeatability factor was 0.86%, and the pulse response time was 39 μs. The designed capacitive sensor has a simple structure, high measurement accuracy, and strong robustness, and it can be integrated into ball joint applications in the frames of aeronautical photoelectric pods.