An apparatus and method for measuring the velocity of a relative movement between first and second bodies or between a first body and a fluid. The first body may be stationary and the second body a moving body, such as hot strip steel. Alternatively, the first body may be an aircraft or ship whose velocity is to be measured or it may be a pipe or duct along which a fluid is flowing. At least two detectors are mounted on the first body and serve to detect noise signals representing disturbances in the fluid or on the second body. Correlating means generate data for producing at least two correlation or autocorrelation curves from the signals from the detectors. The data from the correlating means is then combined to enable production of a combined cross-correlation or auto-correlation curve, from which the relative velocity can be computed.
An ultrasonic measuring system for a vehicle is composed of first and second ultrasonic transducing assemblies TR1 and TR2. Each transducing assembly TR1, TR2 has three ultrasonic transducers TR11, TR12, TR13, TR21, TR22, TR23 which are separated from each other at an angle of 120 degrees in a horizontal plane about axis disposed at a front and a rear of the vehicle, respectively. Each transducer transmits ultrasonic waves to a road surface at a predefined down-angle relative to the road surface and receives reflected waves from the road surface. Each of the transducers TR21, TR22, TR23 transmits ultrasonic waves to the road surface and receiving reflected waves from the road surface in an opposite direction to a corresponding one of the transducers TR11, TR12, TR13. A two dimensional speed, a yaw rate and a yawing center are obtained by differences of first three speed vectors in three directions obtained by the first ultrasonic transducing assembly TR1 and second three speed vectors in second three directions, corresponding to the first three directions, obtained by the second ultrasonic transducing assembly TR2.
The sensor (20) is intended for the detection of random signals, suitable for correlative signal processing, originating from a process in motion relative to the sensor, for example a flow passing through a pipeline (1). Signals of this nature are used, in particular, for the measurement of velocity or running time. The sensor (20) is subdivided into several sensor segments (21, 22, 23, 24) in order to increase sensitivity for a given spatial frequency filter effect. In the case of a capacitive sensor, each sensor segment consists of two electrodes encompassing the pipeline (1). The sensor segments (21, 22, 23, 24) are arranged along the direction of motion according to a coding selected on the basis of the desired spatial frequency filter effect, with the introduction of gaps (25, 25, 27) which are insensitive to the characterizing parameter of the process in motion. The spatial frequency filter effect and, in particular, its limit frequency, will then correspond to that of an individual sensor segment, while the total aperture, which determines the sensitivity, is equal to the sum of the aperture segments of the sensor segments present.
An apparatus and method for processing first and second signals, the second signal representing information which is delayed in time with respect to correspoonding information represented by the first signal and there being included in the information represented by each signal information which represents a common effect, occurring at the same time, in each of the two signals. The apparatus includes correlating means which generate first data suitable for producing a positive time correlation curve from the two signals and second data suitable for producing the equivalent of a negative time correlation curve from the two signals or an autocorrelation curve from either one of the two signals. The information representing the common effect results in data common to both first and second data. One of the first and second data is therefore subtracted from the other, thereby removing or substantially reducing the information representing the common effect. The apparatus and method are particularly suited for measuring the speed of travel of a cable in a cable making machine, where lateral movements of the cable away from its desired path produce a common effect on sensors spaced lengthwise of the direction of travel.
A cross correlation flowmeter for measuring a flow rate of a fluid comprises a conduit through which the fluid to be measured the flow rate is flowing, first and second upstream sensors disposed on the conduit along a longitudinal direction thereof for sensing passage of the disturbance, a plurality of downstream sensors disposed on the conduit along the longitudinal direction of the conduit at a downstream side relative to the first and second upstream sensors for sensing the passage of the disturbance, first flow velocity detecting circuit for detecting a first flow velocity by calculating a maximum of a cross correlation of output signals from the first and second sensors, selecting circuit for selecting one of the downstream sensors providing a maximum accuracy of the flow rate responsive to the first flow velocity, and flow rate calcualting circuit for calculating the flow rate by finding out a maximum of the cross correlation of output signals from the first upstream sensor and the selected one of the downstream sensor.
The present invention provides a generally contactless method and apparatus for producing a speed reference for a rail vehicle which amenable to retrofit applications. The invention utilizes a laser source to direct a laser beam on a portion of the wheel and axle assembly of the rail vehicle. In presently preferred embodiments, the laser beam is directed on a tread or flange section of the vehicle wheel. The laser beam is believed to excite the molecules on the surface of the wheel in such a way that magnetic susceptibility is significantly increased. The increased magnetic susceptibility facilitates encoding of a magnetic signal by a magnetic encoding head. This magnetic signal may then be received after further rotation of the wheel by an angularly displaced magnetic receiving head. Processing circuitry is electrically connected to the magnetic encoding head and the magnetic receiving head to derive the speed reference based on the angular velocity and dimensions of the wheel. An erasing head may also be provided to remove the magnetic signal after detection by the receiving head.
