School of Mechanical Engineering, Hangzhou Dianzi University, Hangzhou 310018, China.
School of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China.
Sensors (Basel). 2018 Oct 9;18(10):3366. doi: 10.3390/s18103366.
A spherical joint is a commonly used mechanical hinge with the advantages of compact structure and good flexibility, and it becomes a key component in many types of equipment, such as parallel mechanisms, industrial robots, and automobiles. Real-time detection of a precision spherical joint clearance is of great significance in analyzing the motion errors of mechanical systems and improving the transmission accuracy. This paper presents a novel method for the micro-clearance measurement with a spherical differential capacitive sensor (SDCS). First, the structure and layout of the spherical capacitive plates were designed according to the measuring principle of capacitive sensors with spacing variation. Then, the mathematical model for the spatial eccentric displacements of the ball and the differential capacitance was established. In addition, equipotential guard rings were used to attenuate the fringe effect on the measurement accuracy. Finally, a simulation with Ansoft Maxwell software was carried out to calculate the capacitance values of the spherical capacitors at different eccentric displacements. Simulation results indicated that the proposed method based on SDCS was feasible and effective for the micro-clearance measurement of the precision spherical joints with small eccentricity.
球关节是一种常用的机械铰链，具有结构紧凑、灵活性好的优点，它已成为许多类型设备中的关键部件，如并联机构、工业机器人和汽车。实时检测精密球关节间隙对于分析机械系统的运动误差和提高传动精度具有重要意义。本文提出了一种基于球差电容传感器（SDCS）的微间隙测量新方法。首先，根据变间距电容传感器的测量原理，设计了球形电容极板的结构和布局。然后，建立了球和差动电容的空间偏心位移的数学模型。此外，采用等位面保护环来减小测量精度的边缘效应。最后，使用 Ansoft Maxwell 软件进行了仿真，计算了不同偏心位移下球形电容器的电容值。仿真结果表明，基于 SDCS 的方法对于小偏心距的精密球关节微间隙测量是可行和有效的。
