Method for locating, and locating device

Abstract

A method for locating an object hidden beneath a surface using a locating device is disclosed. At least one coupling signal dependent on the object is received by a receiving means of the locating device. Once the locating device has been placed on the surface, a first value Ci of the coupling signal is detected and the first value Ci is defined as value CBG for a background subtraction. In particular, whilst the locating device and the surface are moved relative to one another, at least one further value C of the coupling signal is detected and the value CBG for the background subtraction is re-calibrated by the at least one further value C if the at least one further value C is lower than the value CBG for the background subtraction. The re-calibration is suspended if a valid value CBG is identified for the background subtraction.

Claims

1. A method for locating a locatable object hidden under a surface to be searched using a locating device, the method comprising: receiving, with a receiving device of the locating device, at least one coupling signal that is dependent on the locatable object; acquiring a first value of the at least one coupling signal; specifying the first value as a background subtraction value; acquiring at least one second value of the at least one coupling signal; recalibrating the background subtraction value with the at least one second value in response to the at least one second value being less than the background subtraction value; and suspending the recalibrating in response to recognizing a valid background subtraction value.

2. The method as claimed in claim 1, further comprising: recognizing the valid background subtraction value in response to detecting that a predefined time has elapsed since at least one of (i) placing the locating device on the surface to be searched, (ii) switching on the locating device, and (iii) acquiring the first value.

3. A method for locating a locatable object hidden under a surface to be searched using a locating device, the method comprising: receiving, with a receiving device of the locating device, at least one coupling signal that is dependent on the locatable object; acquiring a first value of the at least one coupling signal; specifying the first value as a background subtraction value; acquiring at least one second value of the at least one coupling signal; recalibrating the background subtraction value with the at least one second value in response to at least one second value being less than the background subtraction value; recognizing a valid background subtraction value in response to detecting that the locating device and the surface to be searched have been moved relative to one another by at least a predefined distance; and suspending the recalibrating in response to recognizing the valid background subtraction value.

4. The method as claimed in claim 1, further comprising: recognizing the valid background subtraction value in response to detecting that a difference between a determined maximum value of the at least one coupling signal and a determined minimum value of the at least one coupling signal is greater than a first threshold value.

5. The method as claimed in claim 1, further comprising: recognizing the valid background subtraction value in response to detecting that a difference between a determined maximum value of the at least one coupling signal and the background subtraction value is greater than a first threshold value.

6. The method as claimed in claim 4, wherein the first threshold value is equal to a second threshold value for recognition of the locatable object.

7. The method as claimed in claim 1, further comprising: recognizing the valid background subtraction value in response to detecting that the at least one second value of the at least one coupling signal is greater than the background subtraction value by a predefined value.

8. The method as claimed in claim 1, further comprising: outputting, with an output device of the locating device, information in response to (i) a valid background subtraction value being recognized, and (ii) the at least one second value of the at least one coupling signal being less than the background subtraction value by at least a predefined percentage.

9. A locating device for locating a locatable object hidden under a surface to be searched, the locating device comprising: a receiving device configured to receive a coupling signal from the locatable object; and a control device configured to: acquire a first value of the coupling signal; specify the first value as a background subtraction value; acquire at least one second value of the coupling signal; recalibrate the background subtraction value with the at least one second value in response to the at least one second value being less than the background subtraction value; and suspend the recalibration in response to recognizing a valid background subtraction value.

10. The method as claimed in claim 3, wherein the predefined distance is 10 cm.

11. The method as claimed in claim 3, wherein the predefined distance is 15 cm.

12. The method as claimed in claim 3, wherein the predefined distance is 20 cm.

13. The method as claimed in claim 8, wherein the predefined percentage is 0.15%.

14. The method as claimed in claim 8, wherein the predefined percentage is 0.3%.

15. The method as claimed in claim 8, wherein the predefined percentage is 0.5%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The disclosure is explained in the following description in more detail with reference to the exemplary embodiments illustrated in the drawings. The drawings and the description contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them to form useful further combinations. The same reference signs in the figures identify the same elements.

(2) Here:

(3) FIG. 1 shows a perspective view of a locating device according to the disclosure, placed on a surface to be searched;

(4) FIG. 2 shows a schematic plan view of an implementation of the locating device according to the disclosure including components internal to the device;

(5) FIG. 3 shows a block diagram of exemplary measuring electronics of a locating device according to the disclosure;

(6) FIG. 4 shows a flow diagram of a form of embodiment of the method according to the disclosure.

DETAILED DESCRIPTION

(7) FIG. 1 and FIG. 2 show a perspective view and a plan view of an exemplary embodiment of the locating device 10 according to the disclosure. The locating device 10 described by way of example comprises a housing 12, an input device in the form of actuation elements 14 suitable for switching the locating device 10 on and off, for starting and configuring a measuring process and for the input of working parameters, as well as an output device 16 in the form of a screen for the output of working parameters and/or evaluation results. The locating device 10 has a handle 18 for its transport and guidance. The handle 18, the actuation elements 14 and the screen are located on a first housing side 20 of the locating device 10 which, when the locating device 10 is being used, typically faces the user.

(8) Further components of the locating device, in particular a receiving means 28 and a control device 26, in particular for evaluating coupling signals acquired by the receiving means 28, are housed on a carrier element 24 (cf. FIG. 2), in particular a system board or circuit board inside the housing 12. The components of the locating device 10 are connected together for signaling purposes. The control device 26 comprises control electronics comprising means for communication with the other components of the locating device 10. The control device 26 comprises in particular a unit with a processing unit, a memory unit and an operating program stored in the memory unit. The control device 26 further comprises the method according to the disclosure in its memory, and is configured for carrying out said method.

(9) For the measurement of a coupling signal, in particular for the detection of a locatable object 36 hidden under a surface to be searched 34 of a workpiece 32, the locating device 10 is positioned with its second housing side 22, i.e. the rear of the device, flat in the immediate vicinity of the workpiece 32, in particular in contact with its surface to be searched 34. Coupling signals (not illustrated in detail here), in particular capacitive coupling signals, here penetrate from the locatable object 36 through the second housing side 22 to the receiving means 28. A coupling signal received by means of the receiving means 28 is forwarded, in particular forwarded in the form of a voltage and/or a current, to the control device 26, by which it is evaluated by means of evaluation routines and processed and forwarded to an output device 16. The evaluated measurement result, in particular a detection of a locatable object 36, is displayed on the screen to the user and/or can be transmitted to a further data processing device via a data communication interface of the locating device 10.

(10) The locating device further comprises wheels 44 which serve to acquire a movement of the locating device 10 relative to the surface to be searched 34. The wheels 44 are connected inside the device to a sensor which determines a distance covered by the locating device 10 with reference to the surface to be searched 34 from a rotation of the wheels 44.

(11) FIG. 3 shows a block diagram of an exemplary implementation of measuring electronics of a locating device 10 as is illustrated in FIG. 1. A receiving means 28 is connected via a bandpass filter 38 and a subsequent impedance converter 40, including amplifier stage, to the control device 26. The control device 26 comprises in particular a microcontroller 42 with an analog-digital converter (ADC). Output signals corresponding here to capacitive coupling signals from the locatable object 36 converted into electrical coupling signals—are output by the receiving means 28. Amplitude values, in particular values C.sub.i of capacitances, are then determined in the microcontroller 42 from these coupling signals. The measuring electronics illustrated particularly represent measuring electronics of a passive locating device 10 for locating voltage-carrying lines hidden under the surface to be searched 34, wherein the locating device 10 does not itself emit a locating signal.

(12) In an alternative exemplary embodiment, the measuring electronics can also serve for the generation of a locating signal which is emitted into a workpiece 32, reflected by a locatable object 36 and is also received and evaluated by the measuring electronics. The measuring electronics in particular represent measuring electronics of an active locating device 10 which, for example, serve for the inductive location of metallic locatable objects 36.

(13) FIG. 4 shows a method diagram of a form of embodiment of the method according to the disclosure for locating a locatable object 36 hidden under the surface to be searched 34 by means of a locating device 10.

(14) In method step 100 here the locating device 10 is placed on a surface to be searched 34 of a workpiece 32. In method step 102, a coupling signal, here in particular a capacitive coupling signal between the workpiece 32 and the receiving means 28, is acquired using the receiving means 28, and a first value C.sub.1 is determined from this. This value C.sub.1 is set in method step 104 as the value C.sub.BG for the background subtraction of the locating device 10. From this point on all the coupling signals acquired are reduced by this value C.sub.BG. In method step 106 at least one further value C.sub.i of the coupling signal is determined, in particular while the locating device 10 is moved by a user relative to the surface to be searched 34. If this further value C.sub.i is less than the value C.sub.BG set in method step 104 for the background subtraction (for example less by a threshold value or a threshold factor), the value C.sub.BG for the background subtraction is recalibrated through the at least one further value C.sub.i in method step 110, i.e. is set again, until a recalibration is suspended in accordance with the method. Whether a suspension of the recalibration has taken place is checked in method step 108.

(15) Criteria that serve for the recognition of a valid value C.sub.BG for the background subtraction are checked in method step 112. The criteria are implemented as 5 independent conditions a to e: a. it is detected, by means of the control device 26, that a predefined time has elapsed since placing the locating device 10 on the surface to be searched 34, or since switching the locating device 10 on, or since acquiring the first value C.sub.1; the predefined time is, for example, 5 seconds (in an alternative exemplary embodiment, the measurement of a predefined time is not initiated until at least one of the other conditions b to e has been satisfied); b. using the wheels 44, and by means of the control device 26, it is detected that the locating device 10 and the surface to be searched 34 have been moved relative to one another, in particular have been moved by at least 10 cm relative to one another; c. by means of the control device 26, it is detected that a difference between a determined maximum value C.sub.max of the coupling signal and a determined minimum value C.sub.min of the coupling signal is greater than a threshold value C.sub.s; C.sub.s is, for example, 80 fF (femtofarads); d. by means of the control device 26, it is detected that a difference between a determined maximum value C.sub.max of the coupling signal and the value C.sub.BG for the background subtraction is greater than a threshold value C.sub.s, wherein the threshold value C.sub.s is equal to a threshold value for the recognition of a locatable object; C.sub.s is, for example, 80 fF (femtofarads); e. it is detected by means of the control device 26 that the value C.sub.i of the coupling signal is greater by a predefined value than the value C.sub.BG for the background subtraction.

(16) If none of the criteria a to e are satisfied, then the method starts again at method step 106—represented by the repeating loop 118 (dotted line)—and repeats the method steps 106, 108, 110 and 112. If at least one criterion a to e is satisfied, then the repeated loop 118 suspends the recalibration, so that at a repeated pass of the method from method step 106 a further repeated loop 120 is entered in which the method steps 106, 108, 114 and 116 run again.

(17) In method step 114 information, in particular a warning, is output by means of an output device 16 of the locating device 10 when a valid value C.sub.BG for the background subtraction is recognized in method step 108, and a further value C.sub.i of the coupling signal is less than the value C.sub.BG for the background subtraction, in particular at least 0.3% less than the value C.sub.BG for the background subtraction. Further, in method step 116, information is output when a locatable object 36 is detected.

(18) The method steps 106, 108, 114 and 116 (also of course depending on the user moving the locating device 10 in method step 106) are repeated and in particular carried out continuously or at least quasi-continuously. The repetition of these method steps is suggested by the repetition loop 120 (dot-dash line).

(19) It should also be mentioned that in an alternative exemplary embodiment of the method a different combination of the criteria can be implemented, for example based on the criteria a, c, d and e (if, for example, the locating device does not comprise a position sensor).