METHOD FOR ADJUSTING THE SENSOR SENSITIVITY OF A MOTION SENSOR FOR DETECTING MOVEMENT OF A PILE YARN IN A TUFTING MACHINE AND ADJUSTING SYSTEM

Abstract

Disclosed herein is a method and associated adjusting system for adjusting the sensor sensitivity of a motion sensor for detecting movement of a pile yarn in a tufting machine, provided with several tufting needles, where this pile yarn is incorporated into a fabric. The method includes determining current process data, providing reference data for the sensor sensitivity of the motion sensor, including one or more sets, where each includes a value of a reference sensor sensitivity and corresponding process data, determining a connection between the current process data and the process data of the provided reference data, determining a value for the sensor sensitivity to be adjusted on the basis of this connection and the one or more values of the reference sensor sensitivity of the provided reference data, and adjusting the value for the sensor sensitivity to be adjusted in the motion sensor.

Claims

1. A method for adjusting the sensor sensitivity of a motion sensor for detecting movement of a pile yarn in a tufting machine, provided with several tufting needles, wherein this pile yarn is incorporated into a fabric, the method comprising: determining current process data; providing reference data for the sensor sensitivity of the motion sensor, consisting of one or more sets, wherein each set comprises a value of a reference sensor sensitivity and corresponding process data; determining a connection between the current process data and the process data of the provided reference data; determining a value for the sensor sensitivity to be adjusted on the basis of this connection and the one or more values of the reference sensor sensitivity of the provided reference data; and adjusting the value for the sensor sensitivity to be adjusted in the motion sensor.

2. The method according to claim 1, wherein the process data comprise the machine speed of the tufting machine in order to thereby control the tufting machine.

3. The method according to claim 2, wherein the process data in addition comprise one or more of the following parameters: machine acceleration of the tufting machine, pattern information of the fabric to be produced, yarn thickness of the pile yarn, yarn type of the pile yarn, machine type of the tufting machine, desired type of detection.

4. The method according to claim 2, wherein the one or more sets of reference data define a connection between the values of the reference sensor sensitivity and the corresponding process data expressed in a look-up table and/or a mathematical function.

5. The method according to claim 1, wherein the providing reference data further comprises selecting specific reference data from the provided reference data for the sensor sensitivity of the motion sensor, based on the current process data and wherein, in the determining the connection between the current process data and the process data of the provided reference data, a mathematical relation is determined between the process data of the specific reference data and the current process data in order to determine said connection and wherein, in the determining the value for the sensor sensitivity, the sensor sensitivity is determined by applying the mathematical relation to the values of the reference sensor sensitivities of the specific reference data.

6. The method according to claim 1, wherein the providing reference data for the sensor sensitivity of the motion sensor comprises determining a set of reference data in a learning cycle, consisting of a value of a reference sensor sensitivity and corresponding process data, wherein this learning cycle comprises: determining an expected percentage detection value per unit time; setting a starting value for the sensor sensitivity of the motion sensor; detecting an amount of movement per unit time by means of the motion sensor; comparing this amount to the specific expected percentage detection value per unit time; adjusting the sensor sensitivity set in the motion sensor until the amount of detected movement per unit time corresponds to the specific expected percentage detection value per unit time; adding to the reference data the set consisting of the value of the sensor sensitivity, set in the motion sensor, when the amount of detected movement per unit time corresponds to the specific expected percentage detection value per unit time, as a value of the reference sensor sensitivity and the current process data.

7. The method for monitoring the tension of a pile yarn in a tufting machine provided with several tufting needles wherein this pile yarn is incorporated into a fabric, comprising: generating measurement signals (D.sub.v) by means of a motion sensor which are an indication of the pile consumption of this pile yarn; determining a moving average (D.sub.ma) of the measurement signals (D.sub.v) over a specific time period; and determining whether this moving average (D.sub.ma) exceeds a first limit value and/or drops below a second limit value; wherein a sensor sensitivity is adjusted in the motion sensor (16, 17) which is adjusted according to a method according to claim 1.

8. The method according to claim 7, further comprising: determining an acceptable percentage detection value per unit time; detecting an amount of movement per unit time by means of the motion sensor; comparing the amount of detected movement to the acceptable percentage detection value.

9. The method according to claim 8, further comprising adjusting the sensor sensitivity set in the motion sensor until the amount of detected movement per unit time corresponds to the acceptable percentage detection value per unit time.

10. The method according to claim 8, further comprises adding to the reference data the set consisting of the sensor sensitivity set in the motion sensor as the reference sensor sensitivity and the current process data when the amount of detected movement corresponds to the acceptable percentage detection value.

11. The method according to claim 8, wherein the acceptable percentage detection value is adjustable.

12. The method according to claim 7, wherein the specific time period is adjustable.

13. The method according to claim 7, wherein the limit value is adjustable.

14. The method according to claim 7, wherein the pile consumption of the pile yarn is measured by means of the motion sensor between a yarn storage system and a feeding device for supplying this pile yarn from the yarn storage system in the tufting machine.

15. The method according to claim 7, wherein the measurement signals (D.sub.v) are generated by means of an optical sensor as said motion sensor.

16. The method according to claim 7, wherein the measurement signals (D.sub.v) are generated by means of a piezoelectrical sensor as said motion sensor.

17. The method according to claim 7, wherein the tension of one or more additional pile yarns is monitored by generating corresponding additional measurement signals (D.sub.v) by means of one or more corresponding additional motion sensors, and in that for each monitored pile yarn a moving average (D.sub.ma) of the corresponding measurement signals (D.sub.v) over a specific time period is determined and it is determined whether this moving average (D.sub.ma) exceeds a first limit value and/or drops below a second limit value.

18. An adjusting system for adjusting the sensor sensitivity of a motion sensor for detecting movement of a pile yarn in a tufting machine, provided with several tufting needles, wherein this pile yarn is incorporated into a fabric, wherein this adjusting system comprises: a data unit for reading in current process data; a storage unit for storing reference data for the sensor sensitivity of the motion sensor consisting of one or more sets, wherein each set comprises a value of a reference sensor sensitivity and corresponding process data; and a calculation unit for: determining a connection between the current process data and the process data of the provided reference data; determining a value for the sensor sensitivity to be adjusted on the basis of this connection and the one or more values of the reference sensor sensitivity of the provided reference data; wherein the adjusting system is provided for adjusting the value for the sensor sensitivity to be adjusted in the motion sensor.

19. The adjusting system according to claim 18, wherein this adjusting system is provided for adjusting the sensor sensitivity according to a method comprising: determining current process data; providing reference data for the sensor sensitivity of the motion sensor, consisting of one or more sets, wherein each set comprises a value of a reference sensor sensitivity and corresponding process data; determining a connection between the current process data and the process data of the provided reference data; determining a value for the sensor sensitivity to be adjusted on the basis of this connection and the one or more values of the reference sensor sensitivity of the provided reference data; adjusting the value for the sensor sensitivity to be adjusted in the motion sensor.

20. A monitoring system for monitoring the tension of a pile yarn in a tufting machine wherein this pile yarn is incorporated into a fabric, comprising a motion sensor for generating measurement signals (D.sub.v) which are an indication of the pile consumption of this pile yarn and an evaluation system for determining a moving average (D.sub.ma) of the measurement signals (D.sub.v) over a specific time and for determining whether this moving average (D.sub.ma) exceeds a first limit value and/or drops below a second limit value, wherein this monitoring system comprises an adjusting system according to claim 18.

21. The monitoring system according to claim 20, wherein this monitoring system comprises an adjusting unit for adjusting the specific time and/or for adjusting the limit value.

22. A tufting machine, comprising an adjusting system according to claim 18.

23. A tufting machine, comprising a monitoring system according to claim 20.

24. The method according to claim 1, wherein the values of the reference sensor sensitivities are individually adjusted.

25. The method according to claim 1, wherein the process data comprise one or more parameters that have an effect on the amount of movement to be detected by the motion sensor.

26. The adjusting system according to claim 18, wherein the values of the reference sensor sensitivities are individually adjusted.

27. The adjusting system according to claim 18, wherein the process data comprise one or more parameters that have an effect on the amount of movement to be detected by the motion sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The present invention will now be explained in more detail by means of the following detailed description of some embodiments of tufting machines, monitoring systems and methods according to the present invention. The sole aim of this description is to give illustrative examples and to indicate further advantages and particulars of embodiments of the present invention, and can therefore not be interpreted as a limitation of the area of application of the invention or of the patent rights defined in the claims.

[0062] In this description, reference numerals are to refer to the attached drawings, in which:

[0063] FIG. 1 diagrammatically shows a tufting machine according to at least one embodiment of the present invention; and

[0064] FIG. 2 diagrammatically shows a monitoring system according to at least one embodiment of the present invention.

DETAILED DESCRIPTION

[0065] In the tufting machine (1) illustrated in FIG. 1, pile yarns (3) are supplied from a yarn storage system (creel) (2) (not shown) to the tufting machine (1) by means of a feeding device (4). To this end, the feeding device (4) comprises several yarn-feed modules (5) which are provided with an individual supply, for example, for each pile yarn (3) by providing a drive roller driven by an actuator and a guide roller for each pile yarn (3). In addition, puller rolls (6) are also provided.

[0066] By means of the yarn-feed modules (5) and puller rolls (6), the pile yarns (3) are supplied to corresponding tufting needles (12).

[0067] The puller rolls (6) consist of a pair of rods between the feeding device (4) and the tufting needles (12) through which all pile yarns (3) pass. These puller rolls (6) are arranged in such a manner that they lightly touch each of the pile yarns (3), so that the tension of the pile yarns (3) in the tufting machine (1) is equalized, as the pile yarns (3) are being supplied from different heights and at different speeds.

[0068] The tufting needles (12) are arranged on a needle bar (14) which is movable up and down in the tufting machine (1) by means of one or more connecting rods (13). By moving the tufting needles (12) up and down, the corresponding pile yarns (3) are introduced into a fabric (backing or substrate) (7) in order thus to produce a tufted fabric (8).

[0069] To this end, the fabric (7) is passed from unwinders (10) under the tufting needles (12) by means of cloth feed rollers (9) and rolled back up onto winders (11). To this end, one or more cloth feed rollers (9) are driven rollers, while the other cloth feed rollers (9) are designed as guide rollers.

[0070] The fabric (7) is clamped at the location of the tufting needles (12) by means of a presser foot (15). Furthermore, bed plate mechanisms (18) are present which may comprise grippers for forming loop piles and optionally knives for forming cut piles.

[0071] This construction of tufting machines (1) is known and may be configured in various ways and in various variants, so that this will not be discussed in any more detail in the context of the present patent application. In the case of tufting machines (1) with individual pile delivery, for example, the puller rolls (6) will not be present.

[0072] According to the disclosure, each pile yarn (3) of such a tufting machine (1) is now provided with a corresponding motion sensor (16, 17). This motion sensor (16, 17) may be fitted at various positions in the line of the movement of the corresponding pile yarn (3). In a first illustrated position, the motion sensor (16) is arranged between the feeding device (4) and the tufting needle (12). In a second illustrated position, the motion sensor (17) is arranged between the yarn storage system (2) and the feeding device (4). Several such motion sensors (16, 17) may be fitted at each said position in the same housing in order to install these more easily in the tufting machine (1) as a group. Thus, for example, a housing comprising 16 of such sensors (16, 17) may be provided.

[0073] In the installed position in the tufting machine (1), these motion sensors (16, 17) are provided in order to generate measurement signals (D.sub.v) which are an indication of the pile yarn consumption for each supplied pile yarn (3).

[0074] Various kinds of motion sensors (16, 17) may be taken into consideration for this purpose, such as for example an optical sensor, analogous to that in US 2020/0087103 A1 or a piezoelectric sensor, analogous to that in an Eltex Eye. In the specific embodiments described below, use was made of piezoelectric sensors. These examples also apply mutatis mutandis to other types of motion sensors.

[0075] The monitoring system (20) according to the present disclosure illustrated in FIG. 2 comprises the motion sensors (16, 17) for installation in a tufting machine (1) as illustrated in FIG. 1. A control unit (19) is provided for controlling this monitoring system (20) and to this end comprises, for example, a microprocessor.

[0076] In order to determine a moving average (D.sub.ma) of the measurement signals (D.sub.v) for each motion sensor (16, 17) and to determine whether this moving average (D.sub.ma) exceeds a first limit value (or possibly exceeds one or more limit values) and/or drops below a second limit value (or possibly drops below one or more limit values), an evaluation system (22) is provided. This evaluation system (22) will typically be distributed across the various motion sensors (16, 17) which are each separately or per group (for example per group of 2, 4, 8 or 16) provided with a local part of the evaluation system (22) for determining the moving average (D.sub.ma) of the measurement signals (D.sub.v) and, if desired, comparing this moving average (D.sub.ma) with said one or more limit values. In housings comprising 16 of said motion sensors (16, 17), these motion sensors (16, 17) may, for example, be controlled all together or divided up into various blocks (of 2, 4, 8 or 16) by a local control unit which is in turn controlled by means of the control unit (19). The various motion sensors (16, 17) in one block may in this case be scanned one by one in each case and the resulting measurement signals (D.sub.v) may be compared to the value on a comparator in the local part of the evaluation system (22). The sensor sensitivity corresponding to the motion sensor (16, 17) to be scanned (and optionally also corresponding to the detection zone, if a difference is made in sensitivity in two different detection zones of one machine cycle) may in this case be filled in.

[0077] If desired, the control unit (19) (for example designed as a microprocessor) may additionally be provided with a central part of the evaluation system (22) (implemented in the microprocessor), for example if the control unit (19) further compares, based on the moving average (D.sub.ma), to said one or more limit values or if the motion sensors (16, 17) generate a different signal (S) for each transgression of a respective limit value and the control unit (19) determines, on the basis of this signal (S), whether and which alarm should be generated and whether the tufting machine (1) is possibly stopped. Alternatively, it would also be possible to have the measurement signals (D.sub.v) be read in by the control unit (19) and for the evaluation system (22) to completely form part of the control unit (19).

[0078] By distributing the evaluation system (22) across local parts for one or more motion sensors (16, 17), only limited information has to be exchanged between these motion sensors (16, 17) and the control unit (19) (microprocessor), as the measurement signals (D.sub.v) themselves do not have to be forwarded to the control unit (19). If the measurement signals (D.sub.v) were to be forwarded to the control unit (19), more complex evaluations could be implemented in the central part of the evaluation system (22) and/or further statistical processing of measurement signals (D.sub.v) could be implemented for a longer period of time and/or of measurement signals (D.sub.v) of various motion sensors (16, 17) with respect to each other.

[0079] Each of the motion sensors (16, 17) is assigned a separate identification signal which is sent together with the information of this motion sensor (16, 17) to be forwarded, so that it is possible to record where any errors occur.

[0080] The monitoring system (20) furthermore comprises an adjusting unit (21) (for example a touchscreen) for adjusting said limit values and/or a specific time during which a moving average (D.sub.ma) is to be determined and/or a sensor sensitivity for generating the measurement signals (D.sub.v) and/or the type of pile yarn and/or the type of detection, etc.

[0081] In addition, the monitoring system (20) may comprise a reading unit (23) for reading in data from the tufting machine (1), such as for example the pile pattern and/or the machine speed at which the tufting machine (1) is driven, etc. In order to read in the data, use may optionally be made of a conventional fieldbus or of a separate position channel. Optionally, but less preferred, the data may also be forwarded wirelessly.

[0082] The adjusting unit (21) and/or the reading unit (23) may for example form part of the control unit (19), as is illustrated in FIG. 2.

[0083] In this case, the control unit (19) of the monitoring system (20) may be integrated in an existing control unit of the tufting machine (1) which is additionally configured to control the monitoring system (20), both with completely new tufting machines (1) according to the present disclosure and with any existing tufting machines (1) which are modified to become tufting machines (1) according to the present disclosure. The motion sensors (16, 17) are then installed on such a tufting machine (1), and the control unit of the tufting machine (1) is coupled to the motion sensors (16, 17) in order to control these motion sensors (16, 17) and to read in signals generated by the motion sensors (16, 17).

[0084] Alternatively, it is also possible to configure this control unit (19) completely separately from an existing control unit of a tufting machine (1), as a component of a monitoring system (20) according to the present disclosure, so that a monitoring system (20) according to the present disclosure may also be provided as a separate unit, as a result of which an existing tufting machine (1) can easily be upgraded. It is then for example possible to couple this control unit (19) of the monitoring system (20) to a control unit which is already present in the existing tufting machine (1), for example in order to read in the machine speed (V.sub.m) in order to be able to adjust the sensor sensitivity on the basis thereof or to pass on alarms in order to stop the tufting machine (1) on the basis thereof. The control unit (19) of the monitoring system (20) may, for example, also be coupled to a control unit which is already present in the existing tufting machine (1) in order to read in other data by means of a said reading unit (23) so as to take these data into account when adjusting the sensor sensitivity and/or evaluating the measurement signals (D.sub.v). Thus, the former may be configured to read in a pile pattern in order to determine machine position data (D.sub.m) on the basis thereof for evaluating the measurement signals (D.sub.v) based on these machine position data (D.sub.m). The movement sensors (16, 17) are then installed on this tufting machine (1), and the control unit (19) of the monitoring system (20) is optionally coupled to the control unit of the tufting machine (1).

[0085] Measurement signals (D.sub.v) are generated by means of one or more motion sensors (16, 17). The evaluation system (22) determines a moving average (D.sub.ma) of these measurement signals (D.sub.v) over a specific time period for each motion sensor (16, 17) and determines whether this moving average (D.sub.ma) exceeds a first limit value and/or drops below a second limit value.

[0086] Several limit values may be provided in case of an increase in the moving average (D.sub.ma) and several limit values may be provided in case of a decrease in the moving average (D.sub.ma). Thus, it is possible, for example, for an alarm to be generated when the moving average (D.sub.ma) increases above the first limit value and for the tufting machine to be stopped above a third limit value, which is higher than the first limit value. Analogously, it is possible to generate an alarm if the moving average (D.sub.ma) drops below the second limit value, and for the tufting machine (1) to be stopped below a fourth limit value, which is lower than the second limit value.

[0087] Furthermore, various possible limit values may also be provided for various possible detections.

[0088] In this case, the limit value(s) is/are adjustable by means of the adjusting unit (21). The alarms to be generated and/or the optional stopping of the tufting machine (1) may also be provided to be adjustable via the adjusting unit (21).

[0089] The specific time is also adjustable by means of the adjusting unit (21). In this case, this specific time may be chosen, for example, in function of the desired detection. Thus, for a BED detection, it is for example possible to choose 1 machine cycle as the specific time, or a few machine cycles as the specific time. More specifically, in this case, for example approximately 10 machine cycles may be chosen as the specific time. For a TED detection, it is possible to choose, for example, a longer time or a few tens of cycles. More specifically, in this case, for example approximately 100 machine cycles may be chosen as the specific time.

[0090] At 2000 revolutions per minute, this means, for example, a specific time of 0.3 s for a BED detection and 3 s for a TED detection. At 1500 revolutions per minute, 0.4 s and 4 s, respectively, and at 600 revolutions per minute, 1 s and 10 s, respectively.

[0091] The measurement signals (D.sub.v) are generated at a specific sensor sensitivity. This sensor sensitivity is also adjustable by means of the adjusting unit (21).

[0092] If the sensor sensitivity is too high, movements are detected at machine positions in which the needle is stationary. If the sensitivity is too low, the probability of a movement being detected at a high needle speed is too low (e.g. <0.8). If the sensitivity is too high, such a piezoelectric sensor may miss missing pile yarn, and if the sensitivity is too low, the piezoelectric sensor may emit incorrect reports of yarn breakage.

[0093] In order to determine a value for the sensor sensitivity to be adjusted, the monitoring system (20) may comprise an adjusting system (24) for adjusting the sensor sensitivity of a motion sensor (16, 17). This adjusting system (24) may form part, for example, of the control unit (19). In order to read in the process data of the tufting machine (1), such as the machine speed of the tufting machine (1), the machine acceleration, the characterizing features of the pile yarn (3), the type of detection or pattern information, the adjusting system (24) comprises a data unit (25). In this case, use may optionally be made of a conventional fieldbus or of a separate position channel or, less preferred, the data may also be forwarded wirelessly.

[0094] More specifically, the aforementioned reading unit (21) may also serve as a data unit (25).

[0095] The adjusting system (24) furthermore comprises a storage unit (26) in which reference data for the sensor sensitivity of the motion sensor (16, 17) are stored, consisting of one or more sets in which each set comprises a value of a reference sensor sensitivity and corresponding process data. The one or more sets of reference data define a connection between the value of the reference sensor sensitivity and the corresponding process data. This connection may be expressed in a look-up table or in a mathematical function.

[0096] The adjusting system (24) furthermore comprises a calculation unit (27) in which the connection between the current process data and the process data of the reference data is determined and in which a value for the sensor sensitivity to be adjusted is determined on the basis of this connection and the values of the reference sensor sensitivity of the reference data.

[0097] In the calculation unit (27), either all reference data are retained or the most relevant reference data, based on the current values of the process data, are retained. Only sets of reference data with the same machine type or with a machine speed in a specific interval may, for example, be selected.

[0098] Thereafter, the calculation unit (27) can determine a mathematical relation between the current process data and the process data of the retained reference data, and determine a value for the sensor sensitivity to be adjusted by applying this relation to the reference sensor sensitivities of the retained reference data.

[0099] By using reference data, it is possible to set a sensor sensitivity which is as accurate as possible on the basis of the current process data.

[0100] An additional set of reference data, consisting of a value of a reference sensor sensitivity and corresponding process data, can be determined during a learning cycle. To this end, an expected percentage detection value is first determined.

[0101] The percentage detection value is the percentage of the measurement signals (D.sub.v) which indicates a movement.

[0102] The aim is for the motion sensor (16, 17) to detect the yarn movement and not to falsely detect the non-yarn movement. Based on the physical knowledge of the tufting process, in which the pile yarn (3) is incorporated into the fabric (7), it is known for how much time of every machine cycle the pile yarn (3) moves. In each machine cycle, there is a zone in which there is movement in any case which has to be detected, and there is a zone in which there is no movement and where consequently none should be detected. On the basis thereof, it is also possible to determine what percentage of the measurement signals (D.sub.v) should be permitted to indicate a movement. This percentage is preferably chosen as the specific expected percentage detection value which is strived for in said learning cycle.

[0103] In the motion sensor (16, 17), a starting value for the sensor sensitivity may then be set, for example determined from the already existing reference data.

[0104] The amount of movement detected by the motion sensor (16, 17) can then be compared to this expected percentage detection value per unit time. If this amount of movement does not correspond to the expected percentage detection value per unit time, that is to say it is not within specific predetermined limits of the percentage detection value, e.g. within 20%, 10%, 5% of the percentage detection value, the sensor sensitivity, set in the motion sensor (16, 17), can then be adjusted until the detected amount of movement does correspond to the expected percentage detection value per unit time. Subsequently, the value of the sensor sensitivity set in the motion sensor (16, 17) can be added in the reference data as a value of the reference sensor sensitivity, together with the current process data.

[0105] In this way, a large amount of reference data can be determined, so that a reference sensor sensitivity is available for as many different process data as possible.

[0106] In order to further improve or refine the value of the set sensor sensitivity, a learning cycle may additionally be completed during monitoring of the tension of a pile yarn (3). In this case, the sensor sensitivity may be adjusted, while aiming for a specific acceptable percentage detection value of the movement. The acceptable percentage detection value can be determined in the same way as the expected percentage detection value, it being possible for the expected percentage detection value and the acceptable percentage detection value to have different predetermined limits within which the detected amount of movement has to fall in order to correspond. This acceptable percentage detection value may also be provided in the adjusting unit (21) so as to be adjustable.

[0107] This percentage is preferably chosen as the specific percentage detection value which is strived for in said learning cycle. This may be, for example, 30% as specific acceptable percentage detection value. If, with a set sensor sensitivity, the detected percentage detection value deviates greatly from this specific acceptable percentage detection value, for example 70% to 80%, when the specific acceptable percentage detection value has been adjusted to 30%, then it is clear that this sensor sensitivity has not been adjusted correctly. The sensor sensitivity in the learning cycle is then adjusted until the detected percentage detection value corresponds to the specific acceptable percentage detection value.

[0108] Depending on the type of tufting machine (1) and/or the desired detections, such a sensor sensitivity may be determined in this way for various types of pile yarn (3) and/or for various types of detections and/or for various pile deliveries and/or pile heights and/or on the basis of needle selection data, etc. Below, some specific examples are discussed in more detail. Further sensor sensitivities may be determined, for example via interpolation, and/or may be worked out more precisely with a self-learning system.

[0109] This sensor sensitivity is preferably configured to be adjustable and preferably individually adjustable for each motion sensor (16, 17).

[0110] The sensor sensitivity may, for example, be configured to be automatically adjustable on the basis of a desired detection, such as for example a TED detection or a BED detection.

[0111] In existing tufting machines (1), the sensor sensitivity is optimized for an operating speed of the tufting machine (1). At other machine speeds, only less accurate measurements are possible as the sensor sensitivity is optimized for a different operating speed. By adjusting the sensor sensitivity on the basis of the machine speed (revolutions per minute), more accurate detections at different machine speeds become possible. In order to adjust the sensor sensitivity on the basis of this machine speed, the optimum sensor sensitivity may be determined at 2 or more machine speeds in an above-described learning cycle. Via interpolation, sensor sensitivities to be set for other machine speeds can then be determined.

[0112] If the tufting machine (1) accelerates or decelerates, the sensor sensitivity may in this case also be adjusted on the basis of this acceleration or this deceleration of the machine speed. Thus, errors can be detected as early as possible under all circumstances.

[0113] The optimum set sensor sensitivity can then also be added to the reference data as reference sensor sensitivity, together with the current process data.

[0114] If the motion sensor (16) is arranged between the feeding device (4) and the tufting needle (12), a statistical distribution of these measurement signals may be determined for each machine position in order to determine the sensor sensitivity of the motion sensor (16) to be set on the basis of measurement signals of this motion sensor (16) over several machine cycles as an alternative for the expected percentage detection value or the acceptable percentage detection value.

[0115] In a learning cycle over various machine cycles, the sensor sensitivity of this motion sensor (16) may then be adjusted until the specific statistical distribution virtually corresponds to the typical up and down needle movement over a machine cycle, such as for example described in patent application BE 2023/5287.

[0116] By means of this statistical distribution, the needle cycle of a tufting needle (12) with a specific pile yarn (3) arranged therein can be determined specifically by means of the measurement signals using the corresponding motion sensor (16). The probability with which the motion sensor (16) determines a yarn movement normally virtually corresponds to a typical needle movement. A typical needle movement means that little to no yarn movement is detected when the tufting needle (12) is at its highest point or when the tufting needle (12) is at its lowest point and maximum movement is detected halfway between both points.