FLUID LANCE STOP POSITION SENSOR DETECTION METHOD AND SYSTEM

Abstract

A system for distinguishing target metal objects from each other in close proximity to each other. The method includes transmitting a first sinusoid signal via a first transmit coil to a first receive coil in close proximity to the first transmit coil; transmitting a second sinusoidal signal at a second frequency and amplitude different from the first frequency and amplitude to a second receive coil arranged in close proximity to the second transmit coil and in close proximity to the first receive coil such that received signals in the first and second receive coils include first and second frequency signals from the other of the first and second transmit coils. The received signals are separated via frequency domain multiplexing. The signals are compared to detect a presence of the target having a signal magnitude different from the first received signal and the received second signal and a known reference point.

Claims

1. A system for detecting a target metal object on one of a plurality of flexible hoses arranged in close proximity to each other, comprising: a signal generator generating a first signal having a first frequency and a first magnitude, and a second signal having a second frequency and a second magnitude to the second device; a first transmitting device positioned around a first of the plurality of hoses and in electrical communication with the signal generator to receive the first signal, wherein the first transmitting device transmits the first signal; a second transmitting device positioned around a second of the plurality of hoses and in electrical communication with the signal generator to receive the second signal, wherein the second transmitting device transmits the second signal; a first receiving device positioned around the first of the plurality of hoses proximate to the first transmitting device, the first receiving device receiving the first signal transmitted by the first transmitting device; a second receiving device positioned around the second of the plurality of hoses proximate to the second transmitting device, the second receiving device receiving the second signal transmitted by the second transmitting device, wherein the second receiving device also receives the first transmitted signal and wherein the first receiving device also receives the second transmitted signal; and a signal analyzer separating the first and second transmitted signals received by each of the first and second receiving devices into the first signal received by the first received device and the second signal received by the second receiving device.

2. The system according to claim 1, wherein the signal analyzer is further configured to indicate presence of a first target metal object at a portion of the first of the plurality of hoses within the first transmitting device and first receiving device based on a change in magnitude of the first signal received by the first receiving device, and to indicate presence of a second target metal object at a portion of the second of the plurality of hoses within the second transmitting device and second receiving device based on a change in magnitude of the second signal received by the second receiving device.

3. The system according to claim 1, wherein the first transmitted signal is one of a voltage or a current transmitted from the first transmitting device, and wherein the first received signal is the one of a voltage or a current induced in the first receiving device by the first transmitted signal.

4. The system according to claim 1, wherein the signal analyzer separates the first and second transmitted signals based on differences in frequency and magnitude of the first and second transmitted signals.

5. The system according to claim 4, wherein the signal analyzer separates the first and second transmitted signals based further on differences in phase of the first and second transmitted signals.

6. The system according to claim 4, wherein the signal analyzer comprises a first band-pass filter for use with the first receiving device to filter out the second signal received by the first receiving device, and a second band-pass filter for use with the second receiving device to filter out the first signal received by the second receiving device.

7. The system according to claim 1, wherein the signal generator comprises a first signal generator for the first transmitting device and a second signal generator for the second transmitting device.

8. The system according to claim 1, wherein the signal analyzer comprises a first signal analyzer for the first receiving device and a second signal analyzer for the second receiving device.

9. The system according to claim 1, wherein the signal analyzer separates the first and second transmitted signals via frequency domain multiplexing.

10. The system according to claim 1, wherein the first transmitted signal and the second transmitted signal both comprise frequencies below 30 kHz, wherein the first and second of the plurality of hoses contain a dielectric material therein.

11. A method for detecting a target metal object on one of a plurality of flexible hoses arranged in close proximity to each other, comprising: generating a first signal having a first frequency and a first magnitude, and a second signal having a second frequency and a second magnitude to the second device; receiving the first signal with a first transmitting device positioned around a first of the plurality of hoses and transmitting the first signal with the first transmitting device; receiving the second signals with a second transmitting device positioned around a second of the plurality of hoses and transmitting the second signal with the second transmitting device; receiving the first transmitted signal with a first receiving device positioned around the first of the plurality of hoses proximate to the first transmitting device; receiving the second transmitted signal with a second receiving device positioned around the second of the plurality of hoses proximate to the second transmitting device, the second receiving device also receiving the first transmitted signal and the first receiving device also receiving the second transmitted signal; and separating the first and second transmitted signals received by each of the first and second receiving devices into the first signal received by the first received device and the second signal received by the second receiving device.

12. The method according to claim 11, further comprising indicating presence of a target object at a portion of the first of the plurality of hoses within the first transmitting device and first receiving device based on a change in magnitude of the first signal received by the first receiving device, and indicating presence of a target object at a portion of the second of the plurality of hoses within the second transmitting device and second receiving device based on a change in magnitude of the second signal received by the second receiving device.

13. The method according to claim 11, wherein the first transmitted signal is one of a voltage or a current transmitted from the first transmit coil, and wherein the received signal is the one of a voltage or a current induced in the first receive coil by the first transmitted signal.

14. The method according to claim 11, wherein the separating comprises separating the first and second transmitted signals based on differences in frequency and magnitude of the first and second transmitted signals.

15. The method according to claim 14, wherein the separating further comprises separating the first and second transmitted signals based further on differences in phase of the first and second transmitted signals.

16. The method according to claim 14, further comprising filtering out the second signal received by the first receiving device with a first band-pass filter, and filtering out the first signal received by the second receiving device with a second band-pass filter.

17. The method according to claim 11, wherein the signal generator comprises a first signal generator for the first transmitting device and a second signal generator for the second transmitting device.

18. The method according to claim 11, wherein the separating comprises employing a first signal analyzer for the first receiving device and a second signal analyzer for the second receiving device.

19. The method according to claim 11, wherein the separating comprises separating the first and second transmitted signals via frequency domain multiplexing.

20. The method according to claim 11, wherein the first transmitted signal and the second transmitted signal both comprise frequencies below 30 kHz, wherein the first and second of the plurality of hoses contain a dielectric material therein.

Description

DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a side perspective view of an exemplary three lance hose tractor drive incorporating two lance stop sensor modules in accordance with the present disclosure.

[0013] FIG. 2 is an enlarged partial rear view of the lance tractor drive shown in FIG. 1.

[0014] FIG. 3 is a separate perspective view of a sensor module in accordance with the present disclosure removed from the lance tractor drive shown in FIG. 2.

[0015] FIG. 4 is a sectional perspective view through the sensor module taken along line 4-4 in FIG. 3.

[0016] FIG. 5 is a simplified functional block diagram of an exemplary signal processor for one of the three sensors contained in the sensor module shown in FIG. 3.

[0017] FIG. 6 is a basic overall block diagram showing the signal processor circuit on the printed circuit board embedded in the sensor module.

[0018] FIG. 7 is a set of simplified signal graphs for the signals from lance hoses in a module as shown in FIG. 9.

[0019] FIG. 8 is a block diagram of the mathematics inside the MCU.

[0020] FIG. 9 is a diagram of two lance hoses inside a sensor module.

DETAILED DESCRIPTION

[0021] FIG. 1 is a perspective view of an exemplary application of sensors in accordance with the present disclosure. FIG. 1 shows a multiple flexible lance tractor drive 10 incorporating exemplary embodiments of a stop position sensor module 100 in accordance with the present disclosure. This tractor 10 is configured to reversibly drive from one to three flexible high pressure fluid lances 102, visible as shown in FIG. 2. This tractor drive 10 has a stop position sensor module 100 in accordance with the present disclosure carried in the inlet block 12 and another stop position sensor module 100 carried in the lance guide tube outlet block 13 of the tractor 10.

[0022] FIG. 2 is a perspective view of the rear of the tractor drive 10 showing three flexible lance hoses 15 being pulled simultaneously into and through the tractor drive 10. Each of the lance hoses 15 has a metal stop collar 14 fastened thereto so as to prevent excessive insertion of each of the hoses 15 into the tractor drive 10 These three hoses 15 pass through a stop detection module 100 mounted in a slot in the inlet block 12 of the tractor 10, and are closely arranged, side-by-side.

[0023] A perspective view of a module 100 in accordance with the present disclosure removed from the tractor 10 is separately shown in FIG. 3. Module 100 has a generally rectangular box housing 102 that has three bores 104 therethrough arranged side by side, each sized to receive one of the flexible lance hoses 15 therethrough and receive an elongated portion 16 of the metal stop collar 14 within the bore 104 when the hose 15 has been pulled fully through the tractor drive 10. It is this metal stop collar 14 that prevents the tractor drive 10 from further driving the hose 15.

[0024] A partial sectional view through the module 100 is shown in FIG. 4 with the potted polymeric housing 102 shown in phantom lines. Within the housing 102, encircling each bore 104, is arranged a set of two axially aligned coils: a transmit coil 106 and a receive coil 108. These coils 106, 108 are axially spaced apart by a wear ring 110. Further, each of the transmit and receive coils 106 and 108 are each wound on a protective spool 112. Together, the wear ring 110 and the two spools 112 sandwiching the wear ring 110 define the bore 104 for receiving a lance 15 therethrough, as shown in FIG. 2. Electrical connections to the coils 106 and 108 are potted in the housing 102, and the two lead wires from each coil 106, 108 are fed to signal processing circuit 101 shown in FIG. 5, also potted within the module 100. A cable 114 leading between circuit 101 and a 6-pin connector 116 provides DC power to the signal processing circuit 101. The magnitude and phase data output of circuitry 101 is digitized through a microprocessor within the module 100 and fed via a serial communication protocol on an output pair of leads in the cable 114 to a remote controller (not shown) for the tractor drive 10.

[0025] In the module 100, each transmit coil 106 is excited at a different sinusoidal frequency. As an example, the left one shown in FIG. 3 may be excited at 1.6 kHz. The middle one shown in FIG. 3 may be excited at 2.0 kHz. The right transmit coil may be excited at 2.5 kHz. The separation of frequencies needs to be wider than the useable bandwidth by some margin in order to minimize cross talk between the adjacent sensors. One exemplary bandwidth is 250 Hz, which is sufficient to minimize cross talk between adjacent sensors.

[0026] A general functional diagram of the signal processing circuitry 101 for each detector 101 comprising a coil set 106 and 108, is shown in FIG. 5. In module 100, there are three separate circuits as shown. In general, FIG. 5 depicts a nominal implementation of a metal sensor or detector 101 providing a mechanism such that the nominal characteristics of the detector 101, including phase, , magnitude, M, for a given frequency, f.sub.c, are modified given the presence of a target material, T. This material, T, in this exemplary implementation, is the stop collar 14 as it enters an exemplary one of the bores 104 of the module 100 during operation of the tractor drive 10.

[0027] The circuit 101 comprises an oscillator, 120, a transmitting device, 122, a receiving device, 124, and an analyzer, 126. The oscillator 120 in each of the three identical circuits generates a different frequency signal f.sub.c. The oscillator 120 features the common characteristics of frequency, phase, and amplitude. A preferred implementation of the transmitting device, in the illustrated module 100, is a coil of wire 106 such that the applied transmit signal is either a voltage a current. In the preferred implementation, the receiving device is a second coil of wire 108 arranged such that the received signal is a voltage or a current induced in the receive coil 108. The analyzer 110 discriminates the magnitude and phase characteristics of the received signal.

[0028] In general, the theory of operation basically includes, given a transmitted signal, x, having an oscillation frequency, f.sub.c, a phase, , magnitude, M, and a received signal, y, with similar parameters of phase and magnitude, it is approximated that for any given static proximity of target material. T, the system is linear time-invariant (LTI). As such, the received signal, y, is equal to the convolution of the corresponding impulse response, b, with the transmitted signal:

y(t)=h(T,f)*x(t)

[0029] Note that the impulse response is a function of the target material, T.

[0030] By definition, the Fourier transform provides the following equality:

[00001]$Y\left(f\right)=H\left(T,f\right)X\left(f\right)$$H\left(T,f\right)=\frac{Y\left(f\right)}{X\left(f\right)}$

[0031] Put plainly, the transfer function, H, (defined as the Fourier transform of the impulse response) can be directly computed as the ratio of the Fourier transforms of the received and transmitted signals. By applying sinusoids and/or other deterministic waveforms to the system, H can be approximated at discrete and/or varying frequencies. For example, if a static sinusoid is transmitted, it is assumed that the Fourier transform of the input and output signals are at the frequency of the sinusoid, and that the magnitude and phase of H are well approximated by the analyzer circuit 126.

[0032] In the preferred implementation, the magnitude and phase of the transmitted signal are intrinsically known but could be measured by an additional analyzer, such as analyzer circuit 126 applied to the transmitted signal.

[0033] The preferred implementation includes measurement of both phase, 128. and magnitude, 130. It should be noted that an implementation that does not include both would still be considered to be characterized as an instance of analyzer circuit 126.

[0034] The preferred implementation optionally includes a band-pass filter 127, of a given quality factor, Q, such that Q determines how selective the filter is at the expense of responsiveness to changes in the desired frequency characteristics, and is tuned to the frequency of the transmitted sinusoid to reduce noise in the measurement, as well as distinguish the desired signal from signals from the adjacent sets of coils 106, 108.

[0035] The circuitry 101 of the sensor module 100 in accordance with the present disclosure integrates multiple instances of FIG. 5 (in this case 3), one for each set of transmit and receive coils 106, 108 and one or more instances of the target, T, i.e., each of the hoses 12 and/or presence of hose stop metal collar 16 such that each circuit 126 operates at different sinusoidal frequencies, with the requirement of including tuned band-pass filters 127, and a matched center frequency to the applied frequencies. The inclusion of the band-pass filters 127 provides rejection of frequency components generated by the other nearby transmitter coils 106.

[0036] In other words, the oscillator 120.sub.1 for transmit coil 106.sub.1 produces a different sinusoid signal, f.sub.1, than the sinusoid signal, f.sub.2, produced by oscillator 120.sub.2 and a still different sinusoid signal, f.sub.3, from oscillator 120.sub.3. The receive coils 108 are closely spaced next to each other. Hence, the signals received by each of the receive coils 108.sub.1, 108.sub.2, and 108.sub.3 will be a combination of sinusoid signals from all three of the transmit coils 106.sub.1, 106.sub.2, 106.sub.1. Because these transmit and receive coil sets are closely spaced side-by-side, each tends to pick up the signal from an adjacent set. However, because the frequencies of the transmit coils are chosen in the kilohertz range rather than in high megahertz frequencies, the signal response for each can be separated according to the f.sub.c of the particular oscillator 120. Most importantly, however, is the fact that at the kilohertz frequencies chosen, the presence of water does not mask the presence of a metal such as the extension portion 16 of the stop collar 14 entering within the bore 104 of the module 100 Hence, the magnitude of signal produced by the analyzer circuit 126 when the extension portion 16 is within bore 104 is much greater than when only the lance 15 hose (typically full of water) is present within the bore 104.

[0037] Finally, the receive signals are fed to the PCBA 101, processed, and the measured phase/magnitude data is fed over the serial communication link in the single multithread cable 114. The result is that there are signals of many frequencies that must be separated and analyzed in the three analyzer circuits 126. The analyzer circuit 126 thus is preferably a frequency domain (division) multiplex analyzer circuit that simultaneously analyzes and separates out each of the three signals based on the unique f.sub.c for that particular transmit and receive coil set 106, 108.

[0038] The module 100, in accordance with the present disclosure, coupled with the above described circuitry 101, enables detection and discrimination of the three signals, hence, distinguishing between individual metal objects in close physical proximity from others without interference between the instances.

[0039] FIG. 4 shows a sectional view through the module 100 revealing the configuration of the three transmit/receive coil sets 106, 108 and a printed circuit board (PCB) 200 housed therein upon which the circuitry 101 is fixed. FIG. 6 shows a more detailed block diagram of the printed circuit board 200 within the module 100. This circuit board 200 houses the circuit 101, including the analyzer circuit 126 generally described above. The cable 114, which is attached to the circuit board 200, carries two wires that provide DC power to the circuit 101 and a twin lead communication pair that provides digital signal output to the remote controller (not shown).

[0040] In particular, the analyzer 126 has a microcontroller (MCU) 202 that, among other things, generates, through DACs 204, the transmit signals 120.sub.1, 120.sub.2, 120.sub.3 that excite the coils 106.sub.1, 106.sub.2, 106.sub.3. As previously stated, these transmit signals generated by the oscillators 120 are chosen at different, distinct, frequencies. The signal conditioning blocks 127 effectively condition the signals received from the three receive coils 108.sub.1, 108.sub.2, and 108.sub.3. In addition, the MCU 202 mathematically processes the amplitude/phase detection block 130 shown in FIG. S. A block diagram 206 of the mathematics inside the MCU 202 is shown in FIG. 8.

[0041] Block 206 consists of synchronous sine/cosine functions being heterodyned with the measured signal from the Analog-to-Digital converter, which modulates the desired frequency down to DC. The resulting signals are low-pass filtered to remove components from the interfering frequencies. The resulting data is then packaged and sent out via the communications interface through cable 114. The data format is commonly known as in-phase/quadrature or IQ, and represents a complex number. The magnitude of the complex number is the amplitude of the frequency signal and the angle is the phase. These output signals are read and translated in the remote controller (not shown).

[0042] As an example, consider a situation in which the stop block extension 16 on a hose 15.sub.1 is within the bore 104.sub.1 through transmit coil 106.sub.1 and receive coil 108.sub.1 and there is no stop block extension 16 in the adjacent bore 104.sub.2 within coil set 106.sub.2, 108.sub.2, as shown in FIG. 9. In this situation, the signal from 106.sub.1 as sensed by 108.sub.2 is fairly strong. However, it is of a different frequency. Passing the signal 108.sub.1 through band-pass filter 127.sub.1 generates a large signal amplitude for signal 108.sub.1 and suppresses the signal processed through band-pass filter 127.sub.1 from receive coil 108.sub.2. This is shown in the right hand upper graph of FIG. 7. At the same time, the processing of signals in receive coil 108.sub.2 is shown in the lower set of graphs in FIG. 7. The amplitudes of receive coil 108.sub.2 from transmit coils 106.sub.1 and 106.sub.2 are closer in magnitude. Again, however, they are of different frequencies. Processing the signals from receive coil 108.sub.2 through a band-pass filter tuned to the frequency of transmit coil 106.sub.2 results in a suppression of the signal from transmit coil 106.sub.1 while retaining the magnitude of signal from transmit coil 106.sub.2.

[0043] Comparing the two right hand graphs in FIG. 7, it can be seen that the larger amplitude signal from receive coil 108.sub.1 of signals from the transmit coils 106.sub.1 and 106.sub.2 clearly indicate presence of a different material, i.e., metal, within coils 106.sub.1, and 108.sub.1. In this case, the stop extension's presence causes the signal in adjacent bore 104.sub.1 as measured by 108.sub.1 to be much stronger than that of the signal through band-pass filter 127.sub.2. This difference is utilized by the remote controller as indicative of the presence of the hose stop extension 16 being within the bore 104-.sub.1 of module 100.

[0044] The circuit 101 shown in FIGS. 5-8 for the module 100 shown in FIG. 2 is the same for the module 100 shown in FIG. 1 in the lance guide tube outlet block 13 at the front end of drive 10.

[0045] While the above disclosure has been described with reference to one exemplary embodiment, many changes could be made without departing from this disclosure. For example, while the printed circuit board 200 is shown as extending across the module 100, it could be simplified or miniaturized into a single chip carried within the module 100. Three circuits are described and shown for a three lance module. It is to be understood that a module 100 could alternatively be constructed for two lances, or any number of lances depending on the configuration of the lance drive 10.

[0046] Alternatively, rather than outputting a digital communication signal, as described by the circuitry shown, an analog current or voltage signal such as a 4-20 mA or 0-10v could be outputted by the module 100 for subsequent processing.

[0047] All such changes, alternatives and equivalents in accordance with the features and benefits described herein, are within the scope of the present disclosure. Such changes and alternatives may be introduced without departing from the spirit and broad scope of our disclosure as defined by the claims below and their equivalents.