A new sensor for web flutter measurement is proposed in this paper. The sensor is based on the principle of
scattering of light and directional properties of optical fibers. A collimated beam of light is incident on the web
edge and scattered light from the web edge is collected using a linear array of optical fibers. As the web flutters
the point of scattering moves. Due to the directional property of the optical fibers, each fiber collects scattered
light that is incident on it at certain angles. The motion of the scattering point as the web flutters is directly
related to which fibers are being illuminated within the fiber array. The other end of the fiber array is terminated
onto a linear array of photodiodes (pixels). Based on which fibers in the array are receiving scattered light and
the amount of light received, the transverse displacement (web flutter) of the web can be determined. This paper
describes the construction and working of the new sensor for web flutter measurement. Experiments conducted
on a web platform show that the sensor is capable of accurately measuring web flutter. The frequency response
of the sensor is limited only by the scanning rate of the pixel array and not by the flutter measurement method.
A dedicated signal processing circuit can be used to obtain a desired scanning rate, thus, a desired frequency
A laser based fiber-optic sensor was proposed in our previous work. The sensor developed was based on the
principle of scattering of light and the sensitivity directional property of optical fibers. A beam of light is incident
on a surface or an edge, the scattered light is received by a linear array of optical fibers. The lateral position
of the web edge is determined based on the intensity of light received by each fiber in the fiber array. Static
experiments were conducted to show the feasibility of the sensing strategy.
In this work, the performance of the sensor is evaluated on an actual web handling platform. The analysis
of static and dynamic (with non-zero web transport velocity) experimental data of the sensor under various
realistic operating conditions and disturbances is conducted. A direct comparison of the fiber optic sensor and
two existing industrial sensors is presented. The experimental data from the sensors are compared using different
web materials and under different operating conditions. The new fiber optic sensor is more accurate and the
measurements are less noisy. Further, the new sensor overcomes some of the key limitations of existing sensors.
The problem of determining the actual position of the web when it is completely outside the sensing window or
when it completely covers the sensing windows is resolved; the solution consists of a new configuration. The new
configuration also improves the precision of the sensor.
A new laser based sensing system for measuring the velocity of the web is proposed in this paper. The doppler shift between the incident light and scattered light from a moving particle contains information about the velocity of the particle. A collimated laser source is incident on the web edge and scattered light is collected. The proposed sensing system measures the true velocity of the web by measuring the doppler shift. The doppler shift is measured by heterodyning the scattered light and incident light. The sensor is capable of measuring the web velocity in all three directions, longitudinal, lateral, and transverse. The measurement of the three true velocity components will be highly beneficial for both monitoring and control of webs. The theory of operation of the sensing system is developed based on the reference beam technique. The methods that will be used for processing various signals are given. The architecture of the sensor is described and construction of the sensing system is underway. The experimental platform developed thus far is discussed in detail.
Existing edge sensors use the concept of blocking/unblocking for measuring web lateral position. The most commonly used sensors employ either ultrasonic or infrared signals to detect the web edge position by measuring the amount of signal attenuation due to blocking/unblocking of the signal. The main drawback of this sensing method is nonuniform signal attenuation due to web material variations and opacity. The research in this paper develops a new sensor which utilizes the phenomena of light scattering from the web edge and the directional sensitivity of optical fibers. A collimated laser beam is incident on the web edge and scattered light is collected by a linear array of fibers spatially positioned above the web edge. The theory of operation and the development of the sensor is described. Experiments are conducted with different web materials to validate the proposed sensing method. A representative sample of the results are presented and discussed.