Patent Application
20140145704
The invention relates to a method for localizing objects enclosed in a medium as claimed in the preamble of claim 1 and to a measuring device, especially a hand-held positioning device, for carrying out the method as claimed in claim 14.
Positioning devices have been used for some time for detecting objects such as, for example, electric lines, water lines, pipes, metal stands and also wooden beams, enclosed in a medium such as, for example, a wall, a ceiling or a floor. In this context, inductive devices, among others, are used, i.e. devices which generate a magnetic field which is disturbed by the metallic objects enclosed in a medium. Apart from these inductive devices, capacitive devices, mains voltage detectors and radio-frequency detectors are also used. In the case of mains voltage detectors or also AC detectors, only a receive wire loop system is used in order to detect the desired signal and thus to localize a corresponding object.
The indication whether a sensor detects an object is mostly implemented by LEDs, segmented LCDs and/or graphic displays. In the case of measuring systems of this type, a display is typically used which reproduces the variation of the signal strength of the sensor. That is to say the sensor signal obtained is displayed to the user as an output signal, for example in the form of a bar display or a row of LEDs. The user can thus detect the position of an object by looking with the device for the position having the maximum amplitude of the row of LEDs/bar display.
There are also simpler devices having only one LED which have a fixed threshold for the signal strength. The LED is switched on at the device when the sensor signal exceeds a particular preset value. In this context, there are also devices which do not use a fixed threshold but a threshold which can be changed by the user, i.e. the user adjusts the “sensitivity” at a control knob, this being the threshold of the sensor signal at which the warning lamp/LED of the device lights up.
Furthermore, there are devices (e.g. “DMF 10 Zoom” by Bosch) which do not, or not only, inform the user about the presence of enclosed objects via an LCD display or row of LEDs or a single LED, but via an LED which changes its color. Thus, the “DMF 10 Zoom” mentioned above varies the color of an output unit from green to red as soon as an object has been found. Such a system is known from DE 10 2004 011 285 A1.
Apart from by means of a fixed signal threshold at which an LED of an output unit is activated, i.e. a change in color occurs as in DE 10 2004 011 285 A1, a flowing (adaptive) threshold can also be used which only activates the display and/or LED in the range of the signal peak of the sensor signal which increases the “selectivity” of the object localization. Such a system is known, for example, from DE 10 2005 015325 A1.
In the method according to the invention for localizing objects enclosed in a medium, a measurement signal is generated which enables information to be obtained about the position of the enclosed object. This signal is, for example, a voltage induced in a receive wire loop system of a sensor of a measuring device operating in accordance with the method according to the invention. In this arrangement, an enclosed object can be detected and also localized via the relative signal strength.
From the measurement signal thus obtained which contains information about the position of the enclosed object, an output signal Z (state signal) is generated which enables a user of the method according to the invention or of a measuring device operating in accordance with this method to distinguish between at least three states of detection in the localization. Thus, the method according to the invention generates a first signal Z=a which corresponds to the state “object detected”. A second state “no object detected” can be distinguished via a second signal Z=b which is also generated from the measurement signal.
In the method according to the invention, a third state Z=c containing the information “object in the vicinity” is also advantageously generated. Advantageously, three “warning stages” thus exist in the device which reflect the level of danger of the measurement situation. In particular, these are discrete warning stages and precisely three warning stages which are in each case associated with an unambiguous meaning. This must not be mistaken for a measurement signal which only rises and which signals to a user that the measuring device is moving towards an object that thus must thus be somewhere close in the vicinity. In the method according to the invention, there are three concrete discrete states between which switching is effected.
When using a system having an adaptive threshold as has been mentioned above in conjunction with DE 10 2005 015325 A1, a disadvantage, which is not to be underestimated, of a direct change from the state “no object detected” to the state “object detected” is the fact that the output unit, for example an LED, can indicate “green” (“no object detected”) in such devices even though the user is located above an object, if this object is smaller than an adjacent larger object, since the dynamic threshold for the change of state is determined from the large object. The user could misunderstand the “green” display (“no object detected”) and drill into a hidden object, for example a water line.
The disadvantage of a direct change from the state “no object detected” to the state “object detected” in a method having a fixed preset threshold is the fact that the device warns against an object over a very large area and a precise localization of the enclosed object is scarcely possible (similar to what is observed frequently, for example, in the case of “low-cost devices”).
The additional state Z=c (“object in the vicinity”) advantageously enables the detection threshold, below which the state information “no object detected” is output, to be selected to be very low without there being produced, on the other hand, in the case of strong signals, a distinct and no longer justifiable overdriving in the case of which accurate localization of an individual object would no longer be possible.
The method according to the invention or a measuring device operating in accordance with this method conveys to a user advantageously whether he is not above an object or in the vicinity of an object or directly above an object. In the latter two cases, it is clearly signaled to the user that drilling is or could be dangerous here. Advantageously, at least three “warning stages” are present in the device which reflect the level of danger of the measurement situation. In a particularly advantageous embodiment, precisely three warning stages are provided which are connected with a clear, unambiguous item of information for a user.
By means of the three state or warning stages according to the invention, a user is reliably warned when it could be dangerous and he is informed about the precise position of the object especially by a state information item.
A further advantage of the at least three state or warning stages is that a measuring device operating in accordance with the method according to the invention indicates to a user clearly how the user should behave:
By means of the features listed in the dependent claims, advantageous developments of the localizing method according to the invention are possible.
In the method according to the invention, the system changes advantageously from the first state “object detected” to the third state “object in the vicinity” if the size of the currently measured measurement signal is below a threshold value Uu. This threshold value can be advantageously defined dynamically. Thus, in the method according to the invention, it is possible to change from the first state “object detected” to the third state “object in the vicinity” if the size of the currently measured measurement signal is below the value of a previously measured local maximum value of the measurement signal by a predetermined first percentage.
Devices of the prior art typically convey the information that an object has been detected if the measurement signal exceeds a predetermined measurement signal threshold for object detection. Such a fixed measurement signal threshold has the consequence that in the case where the measurement signal of an object is below this threshold, no object can be detected. If, however, it is an object having a very large measurement signal in which this fixed measurement signal threshold is exceeded already very early, that is to say, for example, at a great distance from the object to be localized, an object can be detected but not localized particularly accurately.
The method according to the invention now limits the state (Z=a) “object detected”, which informs a user that an object has been localized, to a relative signal strength with respect to a measurement signal peak previously measured during the same measuring process. If a measurement signal peak is detected which is typically associated with the localization of an enclosed object, the range of distance allocated to the localized, i.e. detected, enclosed object is limited due to the fact that the measured measurement signal is below a defined percentage of the previously measured measurement signal peak.
In this manner, it is possible, for example, to differentiate between objects arranged closely together which, with a constant measurement signal threshold, would lead to a signal which would lie above the measurement signal threshold over the entire area of the two enclosed objects.
The method according to the invention therefore ensures advantageously also an accurate localization of objects enclosed in a medium.
On the other hand, the method according to the invention changes from the third state “object in the vicinity” (Z=c) to the second state “no object detected” (Z=b) only if the size of the measurement signal currently measured is below a predeterminable first threshold value. This first threshold value can be, for example, the signal noise level of the detection system. The method according to the invention for localizing objects has in the present embodiment preferably a relatively low first threshold value. It is only above this threshold value that an object can be detected at all as such and thus localized.
In this manner, a user can be sure that in the case of the Z=b “no object detected” state, there is really no object present at the location of the measuring point. Wrong measurements of dynamic systems as have been described above can thus be avoided almost completely.
In the opposite case, the method according to the invention changes from the second state “no object detected” (Z=b) to the third state “object in the vicinity” (Z=c) if the size of the currently measured measurement signal exceeds a predeterminable first threshold value, for example the threshold value of the noise level (USR) of the detection system.
The method according to the invention changes from the third state “object in the vicinity” (Z=c) to the first state (Z=a) “object detected” if the size of the currently measured measurement signal (UM) exceeds a predeterminable second threshold value (UU). The predeterminable second threshold value (UU) can correspond advantageously to a previously measured local minimum value (UMin,n) of the measurement signal increased by a predeterminable second percentage P2.
A state Z (Z=a, Z=b, Z=c) can be conveyed advantageously to a user by means of a color code, especially by means of different colors. Thus, the respective detection state Z (Z=a, Z=b, Z=c) can be conveyed to a user especially by means of three different colors. Thus, it is advantageous, for example, to allocate an amber hue to the “object in the vicinity” (Z=c) state.
If the exactly three warning stages are designed analogously to a traffic light (red (Z=a); amber (Z=c); green (Z=b)), such a transmission/indication of state can also be understood intuitively and is self-explanatory worldwide. In this context, the three colors can be implemented separately (one discrete LED per color) or by a single visual display which changes its color (dual- or multi-color LEDs) or by a diffuser which mixes the light of the LEDs and thus generates the colors (e.g. red and green LEDs, when operated simultaneously behind a diffuser, generate the mixed color amber). This could be implemented especially cost-effectively.
Naturally, the transmission of the detected state Z to a user does not need to be effected (purely) visually but can also take place, for example, by means of an audible warning via a loudspeaker or, for example, also a so-called “beeper” in accordance with the same principle, for example with a rising sequence of tones.
Instead of colors or tones, a voice output can also be used for wirelessly transmitting the state to a user.
Further options for transmitting the states in the method according to the invention will be discussed further in conjunction with the measuring device operating in accordance with the method in the text which follows.
By means of the method according to the invention which provides for a more accurate localization of enclosed objects, a user can perform a very accurate localization of enclosed objects merely via the change in state “object detected” or “no object detected” without having to know the accurate variation of the measurement signal. In addition, the user is unambiguously signaled in which situations he can drill without danger, for example into a wall, since there is no enclosed object present at this point.
In normal positioning devices having only two warning stages, namely “no object detected”/“object detected”, the warning that an object is detected must take place very early so that the sensitivity of the device and thus the maximum depth of search does not cut back. The consequence is a warning by LED or beeper over a large area without being able to deduce clear information about where the object is located exactly.
A measuring device operating in accordance with the method according to the invention now no longer indicates the “object detected” state over a wide area of movement. In particular, the measuring area assigned to the localized object is restricted more and more, for example due to the dynamic thresholds when the direction of movement of the measuring instrument is changed several times. By means of the precisely three warning stages existing, the user is reliably warned when it could be dangerous and he is now informed really about the precise position of the object by the first warning stage.
For this purpose, the measuring device according to the invention has output means which allow the state (Z) measured in each case to be reproduced. The state Z (Z=a, Z=b, Z=c) is advantageously reproduced visually, especially by means of three different colors. For example, the different states could be color coded differently. It is also possible to distinguish the different states by a different repetition rate of a visual signal.
If the three warning stages are designed analogously to a traffic light (red (Z=a); amber (Z=c); green (Z=b)), such a transmission/display of state is also understandable and self-explanatory intuitively worldwide.
Naturally, the colors can be selected arbitrarily, green-amber-red naturally being advantageous.
In addition, exactly three warning stages or state indicators Z provide unambiguous information about the basic hazard potential.
For this purpose, the measuring device can have one or more LEDs or be provided with one display as output means.
The colors for transmitting the detection state can be generated, for example, also by the backlight of a segment or graphics display or by an OLED display.
The display (LED array) can be of such a size that it can represent the actual dimensions of the object. In the case of an LED array, the LEDs are then, for example, red above an object, for example amber above uncertain locations and, for example, green in the case of a certain absence of an object.
In the case of a measuring device which is constructed as stud sensor, a modification can also be performed such that, for example, red is indicated above an object, amber for example at the edges of a beam/stud and, for example, green next to the object.
It is especially in the case of devices for detecting beams in lightweight walls that the third warning stage can also be activated if the device is on the right of the left-hand edge of the beam and on the left of the right-hand edge of the beam. This requires an edge detection function but this already exists in the devices for detecting beams according to the prior art. In devices for detecting beams based on low-frequency capacitive sensors, too, the detection of beam edges is possible, e.g. by means of differential measuring electrodes. In this context, local extremes are obtained in the measurement signal at the position of the beam edges. Similarly, such differential measuring electrodes provide for the accurate and unambiguous determination of centers by means of a zero transition in the measurement signal. According to the invention, it is thus also possible that the first warning stage “object detected” is activated only within a very small area around the center of the beam and a further transition stage is activated (for example periodically alternately coded as amber/red) in the area to the left of the center and to the right of the left-hand edge or, respectively, to the right of the center and to the left of the right-hand edge, that is to say over the width of the beam.
A so-called bar chart or a bar scale (or the like) on the display of a measuring device could also be displayed in different colors so that the indication in the display would be combined additionally directly with the color information of the detection state Z.
As a “first color” in the color coding of the three states according to the invention, for example for transmitting the Z=b (“no object detected”) state, an LED which is switched off could also be used, in particular, so that the Z=b, Z=c, Z=b states would correspond to the “off”; “amber”; “red” types of the illumination.
The meaning of the colors/displays/signals of the three warning stages could be explained on the housing of the measuring device, for example also on a sticker as traffic signal symbol or in the online operating instructions in the display of the device.
In other exemplary embodiments, the size of the area of light could also be varied or the brightness could be modulated, for example in three stages.
It would be possible to use LEDs, lamps, other means of lighting, an illuminated hole as in the DMF 10 Zoom device (compare also DE 10 2004 011285 A1), an illuminated housing (e.g. of acrylic), an illumination of the wall or projection of a symbol onto the wall (e.g. line, crosshairs, etc.), laser for representing and transmitting the warning stages/the Z state.
In alternative exemplary embodiments, intermittent light signals (red flashing, red-green alternating flashing, fast or slow flashing) could also be used instead of different colors.
Apart from a visual reproduction of the states, an audible reproduction, for example a state differing in pitch or a different repetition rate of one and the same tone is naturally also possible.
Instead of colors or tones, a voice output could also be used.
As an alternative, a vibration of the device (none-weak-strong) analogous to the vibration alarm of mobile telephones could also be used.
Further more advantageously, the measurement signal is measured as a function of a lateral displacement of a sensor. In this context, one or more sensors are implemented on the positioning device which can detect the presence of metals (inductive sensors), wooden beams (capacitive sensors), voltage-conducting cables (50 Hz sensors) and/or arbitrary objects (radar, UWB, radio-frequency sensors). Such a sensor can have, for example, one or more transmit coils and one receive wire system. In alternative embodiments, such a sensor can have, for example, only one receive wire loop system in order to enable alternating currents to be localized, for example. A capacitive sensor, for example for looking for wooden beams, is also possible. Alternative embodiments of a measuring device can comprise a sensor having an antenna element for sending out and/or detecting RF signals, especially UWB (ultra wideband) signals. An “ultra wideband signal” is intended to be understood, in particular, as a signal which has a frequency spectrum having a center frequency and a frequency bandwidth of at least 500 MHz. The center frequency is preferably selected in the frequency range from 1 GHz to 15 GHz.
The sensors can be integrated in each case individually in a measuring device or also combined to form a number of arbitrary combinations in a single measuring device. In this context, for example, such a measuring device constructed in accordance with the method according to the invention can be displaced or moved over a wall so that corresponding objects such as, for example, metal parts, power cables or also wooden beams which are enclosed in this wall can be localized. In this context, a particular magnitude of a measurement signal is assigned to each position of the measuring device which is then measured, for example, via path sensors of the device.
Such a measuring device for carrying out the method according to the invention which, in particular, can be constructed as a hand-held positioning device, advantageously has output means which allow the “object detected”, “object in the vicinity” or “no object detected” state measured in each case to be reproduced. In this context, a separate output unit can be provided for each sensor present, or the state signals of all sensors combined in the measuring device are output via a central output unit of the measuring device, for example a graphical display. An audible output is also possible. By means of the reproduction of the respective state (“object detected”, “object in the vicinity” or “no object detected”) of individual sensors, a user can thus be informed whether the measuring device is located within the area of a localized object and what type of object this could be.
The measuring device according to the invention has at least one sensor which has at least one receive wire loop system, for example a receive coil. Further transmit or receive coils or also further sensors, respectively, are similarly possible in other embodiments of the measuring device according to the invention. In this context, such a sensor is calibrated in such a manner that in the case of a localization of an object, a signal change in the case of a movement of the device relative to the object becomes measurable. By means of the method according to the invention or, respectively, by means of a measuring device carrying out the method according to the invention, for example a hand-held positioning device, increased accuracy is possible in the localization of the object enclosed in a medium. In spite of the very high dynamic range of the measurement signal generated by the sensor, an improved accurate localization of the object is possible due to the dynamic correlation of states in accordance with the method according to the invention. The first state Z=a, i.e. “object detected” thus just corresponds to the transmission of information “object localized”. Accurate position finding, i.e. localization of an enclosed object thus becomes possible advantageously.
Further advantages of the method according to the invention or of a measuring device for carrying out this method, respectively, can be found in the subsequent description of an exemplary embodiment and the associated drawings.
The drawing shows an exemplary embodiment of the method according to the invention which shall be explained in greater detail in the description following. The figures of the drawing, their description and the claims contain numerous features in combination. An expert will consider these features also individually and combine them to form other or further meaningful combinations.
In the figures:
a shows a diagrammatic representation of the variation of the detected measurement signal and of the reproduced state as a function of the location when using a method according to the prior art.
b shows the measurement situation of a diagrammatic representation forming the basis of the variation of the measurement signal from
a shows a diagrammatic representation of the variation of the detected measurement signal and of the reproduced state as a function of the location when using the method according to the invention.
b shows the measuring situation forming the basis of the variation of the measurement signal from
If a corresponding object is then located in the vicinity of the receive geometry, this object modifies, for example, the field generated by the transmit geometry so that a resultant flux is induced in the receiver, for example in the receive coil. The flux induced in the receive coil or a receive wire loop system, respectively, can then be picked up as measurement voltage, for example at the coil or a down-stream measurement amplifier. The closer the inductive sensor comes to the enclosed object, the greater the detected measurement signal, for example the measurement voltage UM picked up.
Apart from corresponding drive electronics, the associated power supply and an evaluating unit for the detected measurement signal, such a positioning device 24 has, for example, also a graphical display 28 which reproduces an output variable which is correlated with the intensity of the detected measurement signal. The output variable can be represented, for example, in the form of a bar chart 30, the number of illuminated bars between a minimum value and a maximum value representing a measure of the intensity of the measurement signal. Apart from the representation of the output variable shown in
If such a positioning device 24 approaches an enclosed object 12 as would be the case, for example, by displacing the device in the direction of the arrow 32 according to the representation in
It is particularly in devices of the prior art that measuring situations may occur in the vicinity of the enclosed object 12 in which the measurement signal is so strong over a relatively long traveling distance of the positioning device 24 in the area of the object 12 to be detected that the maximum amplitude of the output variable, for example of the measurement voltage UM picked up, is reproduced over the entire range. In this case, precise positioning, i.e. localization of the position of the enclosed object 12 is not possible.
When using a system having a so-called adaptive threshold as has already been described above, on the other hand, the output unit, for example an LED, can indicate “green” (“no object detected”) even though one is located above an object. This happens especially when this object is smaller than an adjacent, larger object since the threshold for the change in state is then determined by the large object. The user could misunderstand the “green” state indication (“no object detected”) and drill into a hidden object, for example a water line. Thus, there exists a disadvantage of a direct change from the “no object detected” state to the “no object detected” state which is not to be underestimated.
a shows the variation of the measurement signal UM and the possible reproduction of the states Z “object detected” “object in the vicinity” and “no object detected”, respectively, in a localizing method having a fixed threshold according to the prior art. In this context, the “object detected” state corresponds to the area Z=a and the “no object detected” state is marked by Z=b in
The basic measuring situation is reproduced in
If the measuring device with its sensor is still far away from an enclosed object 12, the corresponding measurement signal is still low. Measuring devices of the prior art mostly have a detection threshold US. If the measurement signal of an object is below this threshold US, the object is not detected as such and can thus not be localized. In this case, a measuring device outputs an item of information which reflects the state “no object detected” (Z=b). Such a “no object detected” state is assumed in areas b of the lateral path of movement X in the measurement situation shown in
In the method of the prior art according to
In addition, it is also not possible by means of such a method to localize an object 123 which generates a measurement signal UM which is below the measurement signal threshold for object detection. If the measurement signal UM currently measured is below the measurement signal threshold US as is shown in the lateral position X2 in
The method of the prior art, shown in
a and 3b show a corresponding measuring situation when using the method according to the invention. The measuring situation in
a shows, on the one hand, the variation of the measurement signal UM detected by the measuring device, and a state signal (Z) which is generated from the measurement signal UM and which distinguishes between the three discrete states of “object detected” (state Z=a), “object in the vicinity” (state Z=c) and “no object detected” (state Z=b). In particular, the method according to the invention has exactly three states Z.
The method according to the invention for detecting and localizing objects has a relatively low fixed threshold US. It is only above this threshold US that an object can be detected as such at all. The threshold used can be in this case, for example, the noise threshold of the detection system. If the measuring device operating in accordance with the method according to the invention is displaced in the direction of the arrow 32 over the surface 26, the measurement signal UM currently measured increases as shown in
To reproduce the Z=a state or the contrary Z=b state and the Z=c state, it is possible, for example, to use the color signal of three different light-emitting diodes 38 which are integrated in the measuring device 24 as output means. If the Z state changes from “no object detected” (Z=b) to an “object in the vicinity” state (corresponding to Z=c), it is possible to switch, for example, from a green light-emitting diode to an amber light-emitting diode in order to signal to a user that he should now proceed with increased caution since there could be or will be an object in the vicinity of the measuring position.
In the case of further displacement of the measuring device 24 in the direction of arrow 32 in
At a position XMax1, a first maximum value UMax1 is reached for the measurement signal UM. The increase in the measurement signal up to there can be transmitted to a user, for example by means of an additional bar display, should this be desired.
If, in the method according to the invention, the current measurement signal UM drops back to the switchover threshold UU, for example due to further displacement of the measuring device in the direction of arrow 32, that of the state displays changes from the Z=a output (“object detected”) to the Z=c state (“object in the vicinity”). The output of the measuring device thus signals to a user that he has left the precise area of localization of the object found again but that it can still be expected that the object is still “in the vicinity”.
The threshold for the transition from Z=a (“object detected”) to the Z=c state (“object in the vicinity”) can advantageously also be a dynamic threshold. This will be described briefly in the text which follows, additionally referring to DE 10 2005 015325 A1 which should thus also be considered as content of disclosure of the present application.
If, in the method according to the invention having a dynamic threshold, the current measurement signal UM drops, for example due to further displacement of the measuring device in the direction of arrow 32 by a predetermined percentage P1 compared with the maximum value UMax1 measured last, back to a value UU1, the signal Z which characterizes the respective state of the system changes from the Z=a state (“object detected”) to the Z=c state (“object in the vicinity”).
It is thus possible to change, for example, from the Z=a state to the Z=c state if the currently measured measurement signal UM has dropped by 15% compared with the maximum value UMax1 previously measured (i.e. UU1=UMax1*(1−0.15)). In this context, the value of 15% is only a typical value, for example a possible value which should not signal any restriction. Other values are also possible. It is especially possible to optimize this switchover threshold between the Z=a state and the Z=c state in the case of different detection programs for a measuring device to the different response characteristic of enclosed objects due to their material composition. Depending on the sensor principle used (for example inductive sensor, capacitive sensor, AC sensor), this first percentage P1 can also be optimized. It should be noted that this first percentage P1, like a second percentage P2 still to be described, does not represent an absolute value but is based on the respective previously measured amount of the maximum value UMax,n or, in the case of the percentage P2, on a minimum value Umin of the measurement signal UMin,m. The respective change in signal in the measurement signal UM, which is necessary for switching from a Z=a state to a Z=c state or conversely, is thus not absolute but can thus be called dynamic dependent on the magnitude of the existing measurement signal. In addition, this threshold moves due to the different percentages P1 and P2, respectively, of the threshold value definition with each passing of a maximum or minimum of the measurement value U. The result is that even relatively small measurement signals which are generated, for example, by relatively small objects such as, for example, an object 122 or result from an object enclosed deeper in the medium such as, for example, an object 123 are adequately delimited compared with a strong signal such as is generated, for example, by an object 121, so that accurate localization of these individual objects is individually possible.
If the measuring device 24 is moved further in the direction of arrow 32 of
In an advantageous embodiment with a dynamic threshold, the measuring device would again switch from the Z=c state (“object in the vicinity”) to a Z=a state (“object detected”) already at the position XU3. This dynamic threshold for the transition from the Z=c state (“object in the vicinity”) to a Z=a state (“object detected”) can be implemented, for example, as follows.
If the measurement signal UM currently measured rises, starting from a previously detected minimum value, for example UMin1, by a predetermined second percentage P2, the method according to the invention switches the Z state of the signal from Z=c (“object in the vicinity”) to a Z=a state (“object detected”). The second percentage P2 could be, for example, 10%, especially if the first percentage is 15%, these 10% again only being intended to reproduce a typical value and do not represent any restriction on possible values.
Advantageously, however, the second percentage P2 should be selected to be smaller than the first percentage P1 as will still be discussed in conjunction with
If the measuring device is moved beyond the XMax2 position, the measurement signal UM drops again with increasing distance from the enclosed object 122. If the measurement signal UM currently measured drops by the percentage P1 (for example 15% in
If the measuring device 24 according to the invention is moved further in the direction of arrow 32, the measurement signal UM currently measured becomes smaller than the measurement signal threshold US at a position XS2 which leads to a change in the Z=c state to the Z=b state (“no object detected”).
In the case of a further displacement of the measuring device 24 in the direction of arrow 32 beyond the position XS2, the measurement signal UM passes through a further local minimum UMin2 at position XMin2 and subsequently rises again due to the influence of a further object 123 becoming noticeable (see
In an advantageous embodiment, the method according to the invention changes from a Z=b state (“no object detected”) to a Z=c state (“object in the vicinity”) if the minimum value of the measurement signal measured last is exceeded by a defined percentage P2 or the magnitude of the measurement signal UM currently measured rises above a fixed threshold value US, if this is greater. Since the threshold value US is greater than the 10% rise P2 of the UMin2 value of the minimum of the measurement signal last measured (this shall be assumed for illustrating the principle) in the exemplary embodiment of
With a further displacement of the measuring device 24 in the direction of arrow 32, the measurement signal UM currently measured rises due to the approach to the enclosed object 123 and reaches a further local peak, the position of which can be identified with the position of the enclosed object 123, at the position XMax3. If the measuring device is moved beyond this position XMax3 in the direction of arrow 32, the measurement signal UM currently measured drops again due to the increasing distance from the signal-generating enclosed object 123. If the measurement signal UM currently measured drops by a fixed percentage P1, by 15% in the exemplary embodiment of
In the case of a dynamic threshold UM, the second predetermined percentage P2 which serves as condition for switching from a Z=c state (“object in the vicinity”) to a Z=a state (“object detected”) is selected to have a smaller magnitude than the first predetermined percentage P1 which serves as condition for switching from a Z=a state to a Z=c state. Since the percentage is smaller for exceeding a minimum value than for staying below a maximum value, an object can be localized even more accurately when it is traversed several times than when it is traversed once. This relationship is shown again in
If the measuring device is moved in the direction of arrow 32 over the surface 26 of a wall 34, starting from the starting position X0, the measurement signal UM rises initially. If during this process the measurement signal UM currently measured exceeds a threshold value US, a state signal Z is generated from the measurement signal which represents the Z1=c state (“object in the vicinity”). A user is thus informed that there must be an enclosed object 12 in the vicinity. If the measuring device is moved further in the direction of arrow 32, the measurement signal UM currently measured passes the position XMax through a maximum value, the position XMax of which could be identified with the accurate position of the enclosed object 12, for example by means of an additional bar chart display. If the measuring device is moved further beyond the position XMax in the direction of the arrow 32 over the surface 26 of the wall 34, the measurement signal UM currently measured drops again compared with the maximum value UMax without a change in the state Z1=c initially being produced. If the measurement signal UM currently measured drops by a predetermined percentage P1 which is about 15% in the exemplary embodiment of
If the user thereupon changes the direction of travel of the measuring device at a point X1 from the direction of arrow 32 to the direction of arrow 33 in order to identify the precise position of the object, the value UU last measured (reversing point) of the measurement signal UM serves as measured local minimum value. If the measuring device is now moved towards the enclosed object 12 in the direction of arrow 33, the Z2=c state is retained, according to the invention, until the currently measured measurement value of the measurement signal UM exceeds a percentage P2 of the minimum value UU measured last. In the exemplary embodiment according to
If the measuring device is then moved further in the direction of arrow 33, the measurement signal UM currently measured passes again through a maximum value at position XMax and then drops continuously during the further travel in the direction of arrow 33. If the value of the measurement signal UM currently measured drops below a predetermined fixed percentage P1 of the maximum value UMax (this is the case at location X3 in the exemplary embodiment of
As can be seen in
Using a dynamic threshold UU, a user is thus enabled by means of the method according to the invention to localize the precise position of an enclosed object (position XMax in
Thus, for example, a measuring device can provide only the output of the derived signal Z and still enable enclosed objects to be localized accurately. An intensity or amplitude information for the measurement signal, as can be implemented, for example, with continuously operating analog pointer devices or digital bar displays, can be advantageously omitted in the measuring device according to the invention. Naturally, it can be provided also in measuring devices according to the invention that both the signal Z and the measurement signal UM is output.
The measuring device 124 according to the invention has a housing 150 which is formed from a upper and a lower half shell 152 and 154, respectively. In the interior of the housing, at least one sensor having a receive wire loop system, for example a coil arrangement, is provided. Further sensors such as, for example, inductive or capacitive sensors can also be integrated in the measuring device 124. In other exemplary embodiments, however, the measuring device 124 could also be a radar positioning device, for example a UWB radar or also a single frequency radar.
The interior of the measuring device 124 has corresponding signal generating and evaluating electronics and a power supply, for example by batteries or accumulators. Thus, the system could be operated, for example, by means of a Li-ion battery pack, especially a 10.8-V pack. The measuring device according to
Furthermore, the measuring device according to the invention has an operating panel 158 with a row of operating elements 160 which enable the device to be switched on or off, respectively, and possibly starting a measuring process or a calibration process. An operating element 156 can enable a user, for example, to vary the frequency of the measurement signal. In addition, it can also be provided that this variation of the measuring frequency is performed automatically by the device and, in particular, is not accessible to a user.
In the area below the operating panel 158, the measuring device according to
On the side 170 of the measuring device 124 opposite the handle 164, it has an opening 172 penetrating the housing. The opening 172 is arranged concentrically at least with the receive wire loop system 134 of the sensor. In this manner, the location of the opening 172 in the measuring device corresponds to the center of the positioning sensor so that the user of such a device is thus also simultaneously indicated the precise position of any object detected. At the same time, a user can mark by means of this opening the precise position of an object, once localized, on the underground such as, for example, the wall surface examined by passing a marking means through the opening. In addition, the measuring device additionally has on its top marking lines 174 via which the precise center of the opening 172, and thus the position of an enclosed object, can be localized by the user.
The opening 172 is limited by a partially transparent sleeve 176 into which the light of different light-emitting diodes can be fed. If the measuring device detects a measurement signal UM from which a state signal Z=a or Z=b or Z=c is generated in accordance with the method described, the sleeve can be illuminated, for example, in red in order to inform a user that an object has been localized at the location of the opening 172 (Z=a) and he, therefore, should refrain from drilling at this point, for example. If by means of the method according to the invention a signal according to the Z=b state (“no object detected”) is generated, green light can be fed into the sleeve, for example, in order to signal to a user that no object has been localized and he could safely perform, for example, drilling in the area of the opening 172 of the measuring device. If a signal according to the Z=c state (“object in the vicinity”) is generated by means of the method according to the invention, amber light can be fed into the sleeve, for example, in order to signal to a user that, although no object has been localized directly at the current position, he could expect an object in the vicinity and, therefore, increased caution is advisable. To provide the color coding of the three states Z=a, b, c, three different light sources, for example colored diodes can be used, or a mixed signal can also be generated in each case. As well, three concentric sleeves could be used instead of one sleeve.
It is also possible to provide the measuring device without such an opening and to provide only one or more color-producing light-emitting means in or at the housing. In such an alternative embodiment of the measuring device according to the invention, the Z state can also be reproduced directly via output means such as, for example, light-emitting diodes which are arranged visibly in or at the housing of the measuring device.
Further options for transmitting the respective state of the detection system to a user are presented in detail in the advantages of the invention and will not be repeated again at this point.
The method according to the invention or a measuring device operating in accordance with this method is not restricted to the exemplary embodiments shown in the figures.
In particular, the method according to the invention is not restricted to the use of only one transmit coil or one receive wire loop system. Multiple systems are also possible. Such a positioning device could also have, for example, a compensation sensor. Such a sensor comprises, for example, three coils, a first transmit coil being connected to a first transmitter, and a possibly present second transmit coil being connected to a second transmitter and a receive wire loop system serving as receive coil being connected to a receiver. The two transmit coils are fed by their transmitters with alternating currents of a frequency fM and oppositely placed phase. In this arrangement, the first transmit coil induces in the receive coil a flux which is opposite to the flux induced in the receive coil by the second transmit coil. Both fluxes induced in the receive coil thus cancel one another so that the receiver does not detect any receive signal in the receive coil if there is no external metallic object in the vicinity of such a coil arrangement. The flux φ excited in the receive coil by the individual transmit coils depends on various values such as, for example, the number of turns and the geometry of the coils and on amplitudes of the currents fed into the two transmit coils and their mutual phase angle. These values must lastly be optimized in such detectors so that in the case of an absence of a metallic object, the least possible flux φ is excited in the receive coil.
As an alternative, it is also possible to use only one transmit coil and to position the receive system of turns in space in such a manner that in the case of an absence of metallic objects, no voltage is induced in the receive wire structures.
In other exemplary embodiments, however, the measuring device according to the invention could also be a capacitive positioning device or also a radar positioning device, for example a UWB radar or also a single frequency radar.
The combination of a number of sensors in one measuring device is also possible.
In addition, it is also possible and advantageous to integrate a sensor according to the method according to the invention directly or as an attachment in a machine tool or a drilling tool in order to enable a user to work safely with this machine.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2010 039 953.1 | Aug 2010 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/063051 | 7/28/2011 | WO | 00 | 5/8/2013 |
