An Improved Capacitive Sensor for Detecting the Micro-Clearance of Spherical Joints

Wang, Wen; Qiu, Wenjun; Yang, He; Wu, Haimei; Shi, Guang; Chen, Zhanfeng; Lu, Keqing; Xiang, Kui; Ju, Bing‐Feng

doi:10.3390/s19122694

Cited by 11 publications

(8 citation statements)

References 24 publications

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“…The results presented in [6] show that the joint clearance makes the mechanism performance worse; the flexibility of pivot has a clear suspension effect to minimize the negative outputs of joint clearance on mechanisms.…”

Section: Introductionmentioning

confidence: 94%

The Influence of Small Clearances in the Spherical Joints of the Systems on their Dynamic Response

Boazu

2022

Ann_UGAL_TMB

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The paper highlights the influence of small clearances in the spherical joints on their natural frequencies and modes of vibration. Joints with bearings made of materials that involve low friction in the coupling (Teflon and HDPE polyethylene) were considered. Two cases of coupling by means of the spherical joints were considered, namely: the coupling angle of the bars in the spherical joint being of 00 and of 900, respectively. The size of the clearance influences the first natural frequency of the system in the sense of decreasing it, but also in the modification of the vibration modes of the system when even a small clearance appears in the joint.

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Section: Introductionmentioning

confidence: 94%

The Influence of Small Clearances in the Spherical Joints of the Systems on their Dynamic Response

Boazu

2022

Ann_UGAL_TMB

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“…In this section, we briefly review the improved spherical capacitive sensor for clearance measurement in spherical joints. More details can be found in [ 30 ]. The sensor is composed of six spherical capacitive plates ( CP S 1 ~ CP S 6 ) and a ball ( CP e ), as shown in Figure 1 .…”

Section: Measurement Principle Of the Spherical Capacitive Sensormentioning

confidence: 99%

“…However, the fringe effect at the corners of the plates could produce capacitance errors and reduce the measurement accuracy. To reduce the fringe effect of the capacitive sensor, an improved spherical capacitive sensor was then developed [ 30 ]. The sensor has six spherical plates without the sharp corners and thus could greatly reduce the fringe effect.…”

Section: Introductionmentioning

confidence: 99%

Error Analysis of a Spherical Capacitive Sensor for the Micro-Clearance Detection in Spherical Joints

et al. 2020

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Spherical joints have attracted increasing interest in the engineering applications of machine tools, industrial robots, medical equipment, and so on. As one of the promising methods of detecting the micro-clearance in spherical joints, the measurement accuracy of a spherical capacitive sensor could be affected by imperfectness during the manufacturing and installation of the sensor. This work presents error analysis of a spherical capacitive sensor with a differential structure and explores the dependence of the differential capacitance on manufacturing and the installation imperfectness. Five error sources are examined: the shape of the ball and the capacitive plate, the axial and radial offset of the plate, and the inclined installation of the plate. The mathematical models for calculating the capacitance errors of the spherical capacitive sensor are deduced and validated through a simulation using Ansoft Maxwell. The results show that the measurement accuracy of the spherical capacitive sensor is significantly affected by the shape of plates and ball, the axial offset, and the inclined angle of the plate. In contrast, the effect of the radial offset of the plate is quite small.

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“…However, the capacitive sensor does not take account of the effect of electrode installation errors on output signals. Wang et al [ 10 , 11 ] analysed the influence of electrode mounting error on measurement signals, but they did not investigate the effects of installation error on 2-DOF angular displacement. In this study, we mathematically modelled the installation error of the sensor in practical applications and verified the model using finite element analysis.…”

Section: Introductionmentioning

confidence: 99%

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

Yang

et al. 2022

Sensors

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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.

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An Improved Capacitive Sensor for Detecting the Micro-Clearance of Spherical Joints

Cited by 11 publications

References 24 publications

The Influence of Small Clearances in the Spherical Joints of the Systems on their Dynamic Response

The Influence of Small Clearances in the Spherical Joints of the Systems on their Dynamic Response

Error Analysis of a Spherical Capacitive Sensor for the Micro-Clearance Detection in Spherical Joints

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

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