Displacement in Aircrafts ….

Aircraft ….  Blade tip gap measurement of compressor and turbine stage for concentricity  Fan Blade clearance measurement using newly developed contact type gap sensor wands in conjunction with Gapman® (see figure 2)  Displacement measurement under 1832°F (1000°C) temperature conditions in engine R&D.  Spin pit rotor rotational analysis Advantages such as: 1. the ability to handle 1832°F (1000°C), 2.accuracy in the sub-micron range, and 3.small size

Displacement in Automotive….

Automotive…. As component and subassembly dimensions shrink, the sensors used to measure them must also undergo miniaturization. Displacement sensors, for example, often must fit into locations with diameters <1mm, where they measure gaps as small as in. (0.23 mm). Other requirements include:  Operating temperatures to 1832°F (1000°C)  Overall diameter reduced to in. (100 microns)  Accuracy to 8 μin. (0.2 microns)  Immunity to magnetic fields  Response up to 200 kHz  On-vehicle DC modular electronics

Automotive…. Dynamic brake system measurements both in laboratory dynamometers and on the vehicles at test track facilities. By measuring displacement variables on a brake rotor in motion, data can be collected and analyzed to show several characteristics, such as:  Rotor runout (TIR)  Rotor thickness variation  Rotor coning  Thermal expansion  Plate-to-plate orientation (V-ing,  barreling)  Wobble  Ovality

Automotive….

Typical Applications

LVDT

Principle of Operation

LVDT Working of LVDT

Displacement by Capacitive It is this change of capacitance that capacitive sensors use to indicate changes in position of a target. High-performance displacement sensors use small sensing surfaces and as result are positioned close to the targets (0.25-2mm).

Eddy Currents When the distance between the target and the probe changes, the impedance of the coil changes correspondingly. This change in impedance can be detected by a carefully arranged bridge circuit. The eddy currents are confined to shallow depths near the conductive target surface. Their effective depth is given by:

Displacement Laser interferometers are displacement feedback instruments capable of subnanometer resolution and submicrometer accuracy over significant distances. Accuracy of 1 part per million (ppm)-1 micrometer (µm) over 1 meter (m)-is achievable for most applications. To achieve accuracy greater than this requires operating the laser beam in either a vacuum or some inert gas. Most systems, however, operate in open air yet achieve near- ppm accuracy. Compare this with a glass scale, which will expand and contract with changes in temperature (approximately 10 ppm per °C for glass).

Displacement /position A typical system consists of a laser, measuring optics, photodetector receivers with or without fiber optics, and electronics to process the signals into a measurement. By varying the optical arrangement, you can also measure displacement, straightness of motion, and angular motion. You can measure multiple axes using a single laser head by splitting the beam multiple times. You can use interferometers for motion feedback over large distances (20 m isn't uncommon). And the beauty is, there's no cost difference to increase from 1 to 20 m because the laser beam travels until it's reflected by a mirror.

Target position

Laser interferometer

Laser Interferometer- Sagnac Effect

Radar Gun RAdio Detection And Ranging.

Cosine Effect Principle of Operation As long as the angle (alpha) remains relatively small, the error (cosine of alpha) is tolerable. The larger the angle, the larger the error and the lower the displayed (relative) speed. On a straight section of road, radar distance from the road and the range of the target determine the angle

RAdio Detection And Ranging. Angle vs Measured Speed The below figure is a graphical representation of the Cosine Effect for measured speed, as a percentage of true speed versus angle (alpha) between radar and target -- the larger the angle the larger the error and the lower the measured target speed.

RAdio Detection And Ranging. Cosine Effect from an Overpass In the side figure, x represents the horizontal distance and y represents the vertical distance from the road to the radar. The line-of-sight distance is d. If either the horizontal or vertical component is zero, the equations reduce to that shown in the figure -- where d = y (if x = 0), or d = x (if y = 0). When applying the equations, all distances must use the same unit dimensions (feet, meters, etc.).

RAdio Detection And Ranging.

Laser/Radars LASER - Light Amplification by Stimulated Emissions of Radiation RADAR - RAdio Detection And Ranging LADAR - LAser Detection And Ranging LIDAR - LIght Detection And Ranging

Application of Laser Interferometer Inertial guidance systems Global Positioning System

Magnetostrictive sensing The interaction between an electromagnetic field generated by a current pulse and the permanent magnet field of the position- sensing magnet creates a magnetostrictive strain effect that travels along the waveguide at the speed of sound. The tape coil and bias magnet senses the reply pulse

Magnetostrictive sensing A basic magnetostrictive linear sensor with multiple magnets returns a reply signal for each magnet. The elapsed time between the interrogation pulse and the reply signal is used to calculate the position of the magnet

Magnetostrictive sensing Plastic injection- molding machines are a natural application for multiposition magnetostrictive sensors. One sensor can monitor the position of the injection screw, the carriage, the mold position, and the ejector

Magnetostrictive sensing A paper slitter monitors the position of each blade using a single magnetostrictive linear sensor. Some slitters measure as much as 10 m across and can have as many as 60 knives along the same axis. Several magnet sensors are used together for such machines

Magnetostrictive sensing Magnetostrictive sensors come in stroke lengths over 7,000 mm. There is also a flexible housing option to simplify shipping and installation Faster response times with industrial Ethernet protocols, such as EtherCAT, make possible tighter control loops. A typical system can now hit sensor update times of 100 sec for motion- control applications