FALL DETECTION METHOD, CORRESPONDING SYSTEM AND MACHINE

Abstract

The present invention relates to a fall detection method, corresponding system and machine, for detecting the fall of a wear element provided with a three-axis accelerometer of an earth moving machine with the following steps: obtaining an accelerometer measurement of each wear element; determining a rotational position measurement of each wear element with respect to the reference axis based on its accelerometer measurement; determining a mean reference value based on all the rotational position measurements; determining a deviation value of each wear element based on the deviation between its rotational position measurement with respect to the mean reference value; determining that there is a fall of a wear element if its deviation value exceeds a threshold value; and repeating the steps in an iterative manner.

Claims

1. A fall detection method for detecting the fall of a wear element from among a plurality of wear elements of an earth moving machine wherein each wear element is provided with a three-axis accelerometer; wherein at least one reference axis is selected, and said method comprises the following steps when said earth moving machine is in an operative state: a) for each of said wear elements obtaining an accelerometer measurement of said wear element provided by said three-axis accelerometer of said wear element; for each of said at least one reference axis; b) for each of said wear elements, determining a rotational position measurement with respect to said reference axis of said wear element based on said accelerometer measurement of said wear element; c) determining a mean reference value; based on said rotational position measurements of each of said wear elements; d) for each of said wear elements determining a deviation value of said wear element based on the deviation between said rotational position measurement of said wear element with respect to said mean reference value; e) for each of said wear elements, determining that there is a fall of said wear element if said deviation value of said wear element exceeds a threshold value; and f) repeating steps to in successive iterations.

2. The method according to claim 1, wherein each of said three-axis accelerometers comprises three single-axis accelerometers.

3. The method according to claim 1, wherein said accelerometers are piezoelectric accelerometers.

4. The method according to claim 1, wherein each of said three-axis accelerometers is arranged in alignment with its respective wear element.

5. The method according to claim 1, wherein the interval between said successive iterations is between 0.5 and 5 seconds, preferably 1 second.

6. The method according to claim 1, wherein in each iteration, steps to are performed considering only the wear elements for which said accelerometer measurements are available for said iteration.

7. The method according to claim 1, comprising the following additional step: determining that there is a connection loss of a wear element in the event that none of said accelerometer measurements of said wear element is available during N successive iterations; N being a number greater than or equal to 1.

8. The method according to claim 1, wherein each of said at least one reference axis is selected such that, for each of said wear elements said rotational position measurement with respect to said reference axis comprises a pitch measurement or a roll measurement.

9. The method according to claim 1, wherein in said step determining a mean reference value is performed by means of a weighted sum of said rotational position measurements of each of said wear elements.

10. The method according to claim 1, wherein in said step, said deviation value comprises performing a subtraction between said rotational position measurement, and said mean reference value preferably obtaining the absolute value of said subtraction.

11. A fall detection system for detecting the fall of a wear element from among a plurality of wear elements of an earth moving machine, comprising: said plurality of wear elements, each wear element being provided with a sensor comprising a three-axis accelerometer, and wherein said sensor is configured for emitting accelerometer measurements provided by said three-axis accelerometer; a control module configured for: receiving said accelerometer measurements; and carrying out the method according to claim 1.

12. An earth moving machine incorporating a fall detection system according to claim 11.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The advantages and features of the invention can be seen from the following description in which preferred embodiments of the invention are described in a non-limiting manner with respect to the scope of the main claim in reference to the drawings

[0062] FIG. 1 is a perspective view of an excavator shovel provided with wear elements used in the method of the invention.

[0063] FIG. 2 shows a section view of a wear element provided with a three-axis accelerometer therein.

[0064] FIG. 3 is a schematic view of an earth moving machine provided with a fall detection system like the one of the invention.

[0065] FIG. 4 shows a flow chart of a preferred embodiment of the fall detection method of the invention.

DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS OF THE INVENTION

[0066] FIG. 3 shows an earth moving machine 2, in this case an excavator, provided with a plurality of wear elements 1, which comprise, for the example, teeth fixed to the shovel of the excavator. FIG. 1 shows a detail of a shovel and FIG. 2 shows a section of one of the teeth.

[0067] For the example, the earth moving machine 2 incorporates a fall detection system for detecting the fall of a wear element 1 from among said plurality of wear elements 1 of said earth moving machine 2. The system comprises said plurality of wear elements 1, each wear element 1 being provided with a sensor comprising a three-axis accelerometer 3, and in which said sensor is configured for emitting accelerometer measurements provided by said three-axis accelerometer 3. In the examples, the accelerometer measurements comprise accelerations in the three axes expressed in milli g, in which 1 milli g corresponds to 0.0098 m/s.sup.2.

[0068] The system also comprises a control module 5, schematically symbolized in FIG. 3, and configured for receiving said accelerometer measurements and carrying out one of the embodiments of the fall detection method described below. For the sake of clarity, the control module 5 has been depicted outside the cabin of the earth moving machine 2, although in some embodiments it can be located inside same. In the example, a high-gain antenna is used to achieve a suitable radiofrequency link, given that the signals emitted from the wear elements have limited power. Other embodiments use several antennas to improve coverage. For most embodiments, said antenna is secured to the outer rail or the ceiling of the machine 2. This last option is the one shown in FIG. 3.

[0069] In turn, the operator of the earth moving machine 2 may have at their disposal an interface, for example, a display, on which the alarms and/or parameters of the system are shown.

[0070] In some examples, the control module 5 is connected to remote servers for transmitting information. Said connection can be by means of any of the connection means known in the art, for example, a radio link, a connection by means of cellular telephony, etc. These embodiments allow remotely monitoring the system, for example, in relation to the alarms and parameters.

[0071] FIG. 4 shows an exemplary embodiment of the fall detection method for detecting the fall of a wear element 1 from among a plurality of wear elements 1 of an earth moving machine 2 according to the invention. For the sake of clarity, FIG. 4 shows the flow chart only for one wear element 1. As mentioned, each wear element 1 is provided with a three-axis accelerometer 3. For the example, each of said three-axis accelerometers 3 comprises a single piezoelectric three-axis accelerometer arranged in alignment with its respective wear element 1. Other embodiments comprise three single-axis accelerometers, as indicated in FIG. 2, having relative axes X′Y′Z′.

[0072] In the method of the example, at least one reference axis 4 is selected. In particular, for the exemplary embodiments, axes X and Y indicated in FIG. 1 and FIG. 3 are selected, such that rotational position measurements 102 corresponding to pitch 107, which corresponds to a rotation with respect to axis Y, and to roll 108, which corresponds to a rotation with respect to axis X, are obtained. FIG. 4 shows two branches of the flow chart for one of the wear elements 1: a branch corresponding to pitch 107 and another branch corresponding to roll 108.

[0073] Said method therefore comprises the steps described below when said earth moving machine 2 is in an operative state.

[0074] A step (a) which comprises, for each of said wear elements 1, obtaining an accelerometer measurement 100 of said wear element 1, provided by said three-axis accelerometer 3 of said wear element 1. In particular, the sensors incorporated in each wear element 1 deliver acceleration values provided by each three-axis accelerometer 3, with respect to its axes X′, Y′, and Z′. The measurements are received by the control module 5. For each iteration, the following steps are performed considering only those wear elements 1 for which accelerometer measurements 100 are available in said iteration.

[0075] For each of said at least one reference axis 4, i.e., for the pitch, on one hand, and for the roll, on the other, the method follows the steps described below.

[0076] A step (b) which comprises, for each of said wear elements 1, determining a rotational position measurement 102 with respect to said reference axis 4 of said wear element 1 based on said accelerometer measurement 100 of said wear element 1. In the case of the example, a pitch measurement for reference axis Y, as well as a roll measurement for reference axis X, is obtained.

[0077] A step (c) which comprises determining a mean reference value 103 based on said rotational position measurements 102 of each of said wear elements 1. For the sake of clarity, FIG. 4 only shows the flow chart for one of the wear elements 1. However, the contributions of the rotational measurements 102 of all the wear elements 1 are required to determine said mean reference value 103. The contribution of wear elements 1 which are not shown has been depicted with a thick horizontal arrow connected to the box with reference 103.

[0078] In the case of the example, said mean reference value 103 is obtained by means of a weighted sum of said rotational position measurements 102 of each of said wear elements 1, initially with the same weighting for each of the wear elements 1.

[0079] A step (d) which comprises, for each of said wear elements 1, determining a deviation value 104 of said wear element 1 based on the deviation between said rotational position measurement 102 of said wear element 1 with respect to said mean reference value 103. For the example, said deviation value 104 is obtained as the absolute value of the subtraction between said rotational position measurement 102 and said mean reference value 103.

[0080] A step (e) which comprises, for each of said wear elements 1, determining that there is a fall of said wear element 1 if said deviation value 104 of said wear element 1 exceeds a threshold value 105.

[0081] The method also comprises repeating steps (a) to (e) in successive iterations. In particular, for the examples, the interval between said successive iterations is 1 second. In this sense, the return arrow between the box labeled with 105 and the initial box labeled with 100 simply indicates a new iteration.

[0082] Another embodiment of the method comprises the additional step of determining that there is a connection loss of a wear element 1 in the event that none of said accelerometer measurements of said wear element 1 is available during N successive iterations. In which N is a number greater than or equal to 1, preferably corresponding to 30 seconds.