China
Africa
Explore chapters and articles related to this topic
Human Occupancy Detectors
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
There are numerous ways of designing a displacement senor for monitoring the membrane deflection [15]. As an example, Figure 69.22b illustrates a capacitive displacement sensor, where the sensing chamber was built in form of a flat capacitor with two plates. The first plate of a capacitor is a metal foil (or metalized plastic membrane) and the other plate is a metal layer on the backplate. The baseline gap d between the membrane and backplate should be rather small—a few millimeters maximum. A value of the capacitance C will change when distance d varies according to the air pressure differential. The capacitance variations are measured and converted into a useful signal.
Dimensional Metrology
Published in Richard Leach, Stuart T. Smith, Basics of Precision Engineering, 2017
Massimiliano Ferrucci, Han Haitjema, Richard Leach
The specific material is of no consequence to position measurements. Capacitive displacement measurements are, however, sensitive to the gap material and are typically most reliable when only air is present between sensor and target. The measurement range for capacitive sensors is from 10 μm up to 10 mm. Capacitive displacement sensors are known for high sampling frequencies (20 kHz or greater) and nanometre resolution (Wilson 2005). Sub-nanometre resolution can be achieved for instruments with smaller measurement range (Fleming 2013).
Fretting wear characteristics of 60Si2MnA steel for high-speed railway rail fastener clips
Published in International Journal of Rail Transportation, 2023
Zhangyue Qin, Yong Zeng, Chao Su, Mengxue Yi, Xinlu Yuan, Pingdi Ren
The tests were conducted on a self-developed fretting wear tester (model: MFC-01). Its structure principle is shown in Figure 6. The piezoelectric ceramic actuator (PZT actuator) of the wear tester was placed on the base and output a sinusoidal fluctuation type fretting displacement. The fretting displacement was transmitted to the upper fixture through the moving rod to drive the horizontal movement of the ball specimens mounted on the upper fixture. The high-precision capacitive displacement sensor could then measure the fretting displacement. The handwheel was turned to move the linear slide downward so that the ball specimens were in contact with the plane specimens, and the normal load F could be measured by the high precision pressure sensor above the pressure spring. The plane specimens were mounted on the lower fixture, which was connected to the base by a linear guide rail and a linear guide plate. During the test, the computer system collected the real-time tangential force and displacement data and displayed the Ft-D curve on the computer screen.