Method for boil phase detection

Abstract

A method for determining a boil phase of a substance (1) acoustically, wherein a plurality of processed first sound samples are compared to a first reference pattern (P1), yielding at least one first correlation number (r1), followed by comparing a plurality of processed second sound samples to a second reference pattern (P2), yielding at least one second correlation number (r2); and confirming a boil phase of the substance (1) by determining that the at least one first correlation number (r1) is equal to or larger than a first pre-set value (s1), and that the at least one second correlation number (r2) is equal to or larger than a second pre-set value (s2).

Description

[0001] Method for boil phase detection

[0002] Field of the invention

[0003] The present invention relates to a method for boil phase detection, in particular a method for acoustic boil phase detection of a substance in a cooking utensil such as a pan or oven. In a futher aspect the present invention relates to a cooking utensil for acoustic boil phase detection of a substance in the cooking utensil.

[0004] Background

[0005] Patent publication US 6,236,025 B1 relates to an acoustic sensing system for boil state detection and method for determining at least one boil state of contents of a cooking utensil. The method comprises the steps of sensing at least one acoustic emission emanating from the cooking utensil and the contents; filtering and amplifying the acoustic emission; and receiving a reference signal. Then the method further comprises the step of analysing the acoustic emission and the reference signal; and generating a boil phase signal indicative of a boil state in response to the step of analysing the acoustic emission and reference signal. In an embodiment, the reference signal comprises a respective temperature representative of the contents of the utensil.

[0006] Summary

[0007] The present invention seeks to provide an improved method for acoustic boil phase detection of a substance in a cooking utensil such as a pan or oven, wherein the method reduces detection complexity yet allows accurate and reliable detection of a boil phase of the substance.

[0008] According to the present invention, a method as described above is provided, wherein the boil phase of the substance is heated by the cooking utensil, and wherein the cooking utensil comprises an acoustic sensor, and wherein the method comprises the steps of: a) recording a plurality of first sound samples measured by the acoustic sensor as the substance is being heated by the cooking utensil; b) processing the plurality of first sound samples, yielding a plurality of processed first sound samples; c) comparing the plurality of processed first sound samples to a first reference pattern, yielding at least one first correlation number; and further comprising the subsequent steps of d) recording a plurality of second sound samples measured by the acoustic sensor; e) processing the plurality of second sound samples, yielding a plurality of processed second sound samples; f) comparing the plurality of processed second sound samples to a second reference pattern, yielding at least one second correlation number; and confirming a boil phase of the substance by the steps of g) determining that the at least one first correlation number is equal to or larger than a first pre-set value, and h) determining that the at least one second correlation number (r2) is equal to or larger than a second pre-set value.

[0009] According to the invention, the first and second reference patterns may be chosen according to specifications that indicate particular characteristic acoustic trajectories / stages of the heating process of the substance. The first and second reference patterns may be based on experiments and / or models, for example. The first and second correlation numbers can be determined by any method deemed reliable and accurate. Furthermore, the first and second preset value can be chosen to meet a required level at which the plurality of processed first and second sound samples is expected to sufficiently match the first and second reference patterns. Since the first and second reference patterns and the first and second pre-set values can be chosen, the method can be executed with any required accuracy and confidence level based on the chosen reference patterns and pre-set values.

[0010] In an exemplary embodiment, the first reference pattern comprises an increasing curve of acoustic magnitude and wherein the second reference pattern comprises a decreasing curve of acoustic magnitude. In this embodiment, the heating process of the substance is expected to exhibit an acoustic characteristic or trajectory in which the acoustic magnitude increases for the first plurality of processed sound samples and wherein the acoustic magnitude subsequently decreases for the plurality of processed second sound samples. In an embodiment, the increasing curve of acoustic magnitude is a straight curve and wherein the decreasing curve of acoustic magnitude is a straight curve. This embodiment simplifies the step of comparing the plurality of first and second processed sound samples to the first and second reference patterns, respectively, as only an approximate linear acoustic trajectory of the plurality of processed first and second sound samples need to be determined.

[0011] In an advantageous embodiment, the method further comprises the step of i) defining a time interval in which completion of method steps h) relative to step g) must occur for confirming the boil phase of the substance. In this embodiment the time interval allows setting a finite length of time in which correlation must be determined between the plurality of processed second sound samples relative to the first sound samples and the second and first reference patterns respectively. Such a finite time interval ensures that the boiling phase of the substance is determined in an expected amount of time to prevent that completion of method step h) takes too long, which may be indicative that something is wrong with the heating process of the substance. In a further advantageous embodiment, the step of defining the time interval may comprise determining a duration of the time interval based on the aforementioned first reference pattern, e.g. a slope of an increasing curve, e.g. a slope of the linear / straight increasing curve of the first reference pattern. For example, if the plurality of processed first sound samples exhibit an acoustic trajectory such as an acoustic magnitude that correlates with a steeper slope of the first reference pattern, then it may be expected that the boiling phase may be reached faster compared to correlation with a moderate slope of the first reference pattern. This would then lead to a shortened time interval in which the method step h) is expected to complete relative to step g) Short description of drawings

[0012] The present invention will be discussed in more detail below, with reference to the attached drawings, in which

[0013] Figure 1 depicts a cooking utensil comprising a substance;

[0014] Figure 2 depicts a time evolution of temperature together with an acoustic magnitude determined from measurements by an acoustic sensor of a substance being heated;

[0015] Figure 3 and 4 each show a flow diagram representing method steps for boil phase detection;

[0016] Figure 5 shows an example of predefined reference patterns for use in boil phase detection;

[0017] Figure 6 shows an example of processing of sound samples as measured by the acoustic sensor.

[0018] Detailed description of embodiments

[0019] Figure 1 depicts a cooking utensil 2 comprising a substance 1 to be heated. In the depicted embodiment the cooking utensil 2 is a pan for holding the substance 1 . In another embodiment, not shown, the cooking utensil 2 may be an oven. The cooking utensil 2 comprises an acoustic sensor 3, a processing system 4, and a transmitter 5, wherein the processing system 4 is communicatively connected to the acoustic sensor 3 and the transmitter 5. The actual location of the acoustic sensor 3, processing system 4, and transmitter 5 may be chosen based on requirements, but for illustrative purposes the acoustic sensor 3, processing system 4 and transmitter s are located in handles of the pan as shown in Figure 1. It is further depicted that the cooking utensil 2 is positioned on a heat source 7 of a cooking hob 6, for example. The heat source 7 may be an inductive element for heating the cooking utensil 2, but the heat source 7 may also be a gas burner. In an exemplary embodiment, the processing system 4 is configured to activate the transmitter 5 for transmitting a signal to the heat source 7 for controlling heat input to the cooking utensil 2.

[0020] According to the present invention, there is need for reliable and accurate automated detection of a boiling phase of the substance 1 in the cooking utensil 2, thereby allowing the heat source 7 to be controlled once a boiling phase is detected. This improves safety as overboiling of the substance 1 can be prevented.

[0021] The present invention relates to a method for determining, acoustically, a boil phase of the substance 1 heated by the cooking utensil 2, wherein the cooking utensil 2 comprises an acoustic sensor 3 which is used to sense noises / sounds coming from the substance 1 when it is heated.

[0022] In Figure 2 depicts an example of the time evolution of temperature T (see vertical axis on the right) and an acoustic magnitude M (see vertical axis on the left) as processed from measured sound samples provided by the acoustic sensor 3. It is important to note that the acoustic magnitude M need not be limited or construed as an acoustic amplitude of measured sound samples. Instead, the acoustic magnitude M may be construed as a generalized magnitude or metric of processed sound samples useful for analysis. Further details and embodiment of the acoustic magnitude M will become clear later.

[0023] The graph for the acoustic magnitude M is shown in distinct stages or trajectories of acoustic magnitudes A1 to A5. The graph of temperature T and acoustic magnitude M are overlayed to show how the temperature T and the acoustic magnitude M may relate as the substance 1 in the cooking utensil 2 is heated from time t = 0. Just for illustration, the substance 1 may be at room temperature of T1 = 21 °C at t = 0. Somewhat higher or lower temperatures T1 are of course possible. As for the temperature T of the substance 1 , an increasing temperature 72 is typically seen when the heating process starts and steadily progresses. At some time point tb, the temperature 73 of the substance 1 reaches a point which can be referred to as boiling, e.g. 100 °C for water at atmospheric pressure.

[0024] As further shown in Figure 2, the acoustic magnitude A1 as processed from measurements provided by the acoustic sensor 3 progresses substantially horizontally in the beginning of the heating process. During the increasing temperature 72, an increasing number of collapsing bubbles are formed in the substance 1 as a result of which an increasing acoustic magnitude A2 is often seen. Just prior to boiling of the substance 1 , a maximum acoustic magnitude A3 is achieved, and at that point the temperature 72 starts to level off to the boiling temperature 73 and a decreasing acoustic magnitude A4 is seen when approaching temperature 73. When the substance 1 reaches the boiling temperature 73, the acoustic magnitude A5 remains substantially constant as boiling behaviour of the substance 1 remains steady.

[0025] It is noted that the depicted acoustic magnitudes A1 to A5 represent the time evolution of processed acoustic data, i.e. sound samples, and as such show a more smoother evolution compared to “raw” sound measurements directly taken from the acoustic sensor 3. Such raw sound measurements would show a much more erratic and noisy acoustic trajectory for the substance 1 .

[0026] Based on the above exemplary acoustic magnitudes A1 to A5 in Figure 2, the method for determining the boil phase of the substance 1 according to the present invention is summarized by Figures 3 and 4, each showing schematic representations of main method steps for acoustic boil phase detection.

[0027] Figure 3 shows three main steps S1, S2 and S3 of the method for determining a boil phase, wherein step S1 represents processing sound samples as measured and provided by the acoustic sensor 3 when the substance 1 is being heated. Step S2 represents a step wherein the processed sound samples are compared to pre-created or predefined reference patterns stored in a repository or database D. In step S3 it is determined whether the processed sound samples correlate or match with the predefined reference patterns to a required degree, and if that is the case, then a boiling phase of the substance 1 may be confirmed. In an exemplary embodiment, the predefined reference patterns may represent reference patterns of acoustic magnitudes as a function time.

[0028] Figure 4 depicts sub-steps S11, S12, S13 of the step S1. As mentioned above, S1 represents a processing step for sound samples measured by the acoustic sensor 3 as the substance 1 undergoes heating. In the embodiment of Figure 4, step S11 may represent filtering sound samples, thereby yielding filtered sound samples. In particular, step S11 may represent a band-pass filter stage. In step S12, a Root Mean Square, RMS, is determined of the filtered sound samples, yielding RMS sound samples. In the following step S13, an average of the RMS sound samples is determined, thereby yielding averaged RMS sound samples. In an embodiment of the present invention, the average may be defined as a mean or median, so that in step S13 a mean or median of the RMS sound samples is determined, yielding mean or median RMS sound samples.

[0029] The averaged RMS sound samples then proceed to the aforementioned step S2, thus wherein averaged RMS sound samples are compared to predefined reference patterns of averaged RMS sound samples. A boiling phase of the substance 1 is determined in step S3 when the averaged RMS sound samples provided by step S13 correlate or match with the reference patterns of averaged RMS sound samples.

[0030] In Figure 5 a representation of step S2 is depicted, where the upper graph shows the step of processed sound samples in the form of an acoustic magnitude M as a function of time t, and wherein the lower graph shows a first reference pattern P1 and a second reference pattern P2 as a function of time. Both reference patterns P1 and P2 represent a predefined reference acoustic magnitude M. As mentioned in light of Figure 2, acoustic magnitude A5 represents a boiling phase of the substance 1 .

[0031] Now, in order for an acoustic trajectory to reach acoustic magnitude A5 from t=0, processed sound samples must follow the depicted increasing curve of acoustic magnitude A2 which is eventually followed by the decreasing curve of acoustic magnitude A4 as time progresses when heating the substance 1 . Therefore, the first reference pattern P1 may be chosen as an increasing curve of acoustic magnitude M and wherein the second reference pattern P2 may be chosen as a decreasing curve of acoustic magnitude M. The existence of increasing and decreasing curves of acoustic magnitudes A2 and A4 in the processed sound samples can subsequently be determined by correlating the processed sound samples with respect to first and second reference patterns P1 and P2 as time progresses.

[0032] When correlating with respect to the first reference P1, at least one first correlation number r1 may be obtained and when correlating with respect to P2, at least one second correlation number r2 may be obtained. The first and second correlation numbers r1, r2 are then compared to a first pre-set value s1 and a second pre-set value s2 respectively. When both the first and second correlation numbers r1, r2 are equal to or larger than their respective pre-set values s1, s2, i.e. r1 >= s1 and r2 >= s2, then it can be determined that the acoustic trajectories of acoustic magnitudes A2 and A4 have been followed as expected and as such a boiling phase of the substance 1 is reached.

[0033] From the above it will be clear that correlation with respect to the first reference pattern P1 and second reference pattern P2 is performed consecutively and that a boiling phase can only be acknowledged when sufficient correlation is determined for both the first reference pattern P1 followed by sufficient correlation with the second reference pattern P2. So both correlations have to occur for concluding that the substance 1 reached a boiling phase.

[0034] Now that the main steps of the method of the present invention have been broadly summarized, the method of the present invention can now be described in more detail using Figure 6, which shows an example of how sound samples from the acoustic sensor 3 can be processed in relation to the first and second reference patterns P1 and P2.

[0035] In particular, the method for determining a boil phase of the substance 1 comprises the steps of: a) recording a plurality of first sound samples 7 measured by the acoustic sensor 3 as the substance 1 is being heated by the cooking utensil 2. The plurality of first sound samples 7 may be considered over an arbitrary number of time intervals Ati, ... Ate for samples as shown in Figure 6, wherein each time interval may span a second for example. Each depicted time interval Ati, ... Ate can be seen as defining a first sound sample of the plurality of first sound samples 7. In a specific embodiment the sample frequency employed for the acoustics sensor 3 may be around 20 kHz, but other frequencies are conceivable depending on requirements.

[0036] The method then involves the step of b) processing the plurality of first sound samples 7, yielding a plurality of processed first sound samples 9,10. Particular examples and embodiments of the plurality of processed first sound samples 9, 10 will be explained later.

[0037] As a next step, the method comprises the step of c) comparing the plurality of processed first sound samples 9, 10 to a first reference pattern P1, as indicated by the arrow C1. This comparing step yields at least one first correlation number r1.

[0038] As time progresses, the method further comprises the step of d) recording a plurality of second sound samples 8 measured by the acoustic sensor 3 followed by the step of e) processing the plurality of second sound samples 8 to obtain a plurality of processed second sound samples 11 , 12. Note that the plurality of second sound samples 8 may also be considered over an arbitrary number of time intervals Atn, ... AtN for samples as shown in Figure 6, wherein each of the time intervals may span a second for example. Likewise, each depicted time interval Atn, ... AtN can be seen as defining a second sound sample of the plurality of second sound samples 8. Particular examples and embodiments of the plurality of processed second sound samples 11 , 12 will become clear later.

[0039] Subsequently, the method continues with the step of f) comparing the plurality of processed second sound samples 11 , 12 to a second reference pattern P2, as indicated by the arrow C2. In this step at least one second correlation number r2 is obtained.

[0040] To confirm a boil phase of the substance 1 , sufficient correlation must be present when the processed first sound samples 9, 10 and processed second sound samples 11 , 12 are compared / correlated to the first and second reference patterns P1 and P2, respectively. Therefore, according to the method, a boil phase of the substance 1 can be confirmed by the steps of g) determining that the at least one first correlation number r1 is equal to or larger than a first pre-set value s1, and h) determining that the at least one second correlation number r2 is equal to or larger than a second pre-set value s2. So when both conditions in step g) and h) are met, it can be concluded that a boil phase is detected.

[0041] It is emphasized that the method of the present invention is sequential in that, temporally, the plurality of processed first sound samples 9, 10 are compared to the first reference pattern P1 before the plurality of processed second sound samples 11 , 12 are compared to the second reference pattern P2. Therefore, sound samples from the acoustic sensor 3 are continuously being recorded, processed and compared to the first reference pattern P1 and subsequently the second reference pattern P2. So for ease of reference, a clear distinction is made between two acoustic trajectories associated with the acoustic magnitudes A2 and A4 as exemplified in Figure 2 and 5. The plurality of first sound samples 7 and the plurality of second sound samples 8 are introduced for referring to temporally separated recordings of which the plurality of first sound samples 7 refer to recordings during the acoustic trajectory of acoustic magnitude A2 and wherein the plurality of second sound samples 8 refer to recordings during the acoustic trajectory of acoustic magnitude A4.

[0042] The method as presented above provides for a customisable, accurate and reliable way to determine as to whether the substance 1 follows an expected acoustic trajectory for reaching a boiling phase of the substance 1 . The predefined first and second reference patterns P1 and P2 can be chosen based on models, experiments etc. to accurately represent parts of the expected acoustic trajectory that the substance 1 follows. When consecutively recorded and processed sound samples satisfy the two correlation requirements mentioned earlier, then a boiling phase can be confirmed with a high degree of confidence. Therefore, selecting first and second reference patterns P1 and P2 allows for specific reference patterns to be selected that closely represent true acoustic behaviour of a particular substance 1 as it undergoes heating. Furthermore, the first and second pre-set values s1, s2 provide two free parameters by which a required degree of correlation can be specified according to requirements.

[0043] In addition to the correlation requirements, i.e. r1>=s1 and r2 >=s2, it is of course possible to impose further checks and conditions that need to be satisfied to achieve higher levels of confidence as to whether a boiling phase is detected. For method steps c) and f), comparing the processed first and second sound samples with the first and second reference patterns can be achieved using known linear or non-linear correlation methods.

[0044] For example, as shown in Figure 5, in an embodiment the method may comprise the step of i) defining a time interval Q (e.g. t2 - 11) in which completion of method step h) relative to step g) must occur for confirming the boil phase of the substance 1. In this embodiment there is a requirement in that the time interval Q cannot be of indefinite duration between determining that the at least one first correlation number r1 is equal to or larger than the first pre-set value s1, and determining that the at least one second correlation number r2 is equal to or larger than the second pre-set value s2. In particular, time interval Q defines a finite time interval from step g) to step h), and wherein this finite time interval Q imposes a finite duration in which completion of step h) relative to step g) must occur for allowing a boil phase to be determined. Setting a finite time interval Q in which step h) relative to step g) needs to complete increases safety. For example, should it take too long for step h) to be completed relative to step g), so wherein the at least one second correlation number r2 never matches or exceeds the second pre-set value s2 within the time interval Q, then this could be indicative of potential issues with the heating process.

[0045] In an embodiment it is conceivable that the method may comprise the step of i) defining a start time interval Qs, starting from e.g. t=0 to t1 as shown in Figure 5, in which step g) is expected to complete. In this embodiment it is possible to impose a finite time interval Qs that starts when the heating process commences at e.g. t=0 and where step g) must complete within an upper time limit t1, for example. Of course, an embodiment is conceivable wherein the method may comprise the step of i) defining the start time interval Qs and the time interval Q, so to improve safety by imposing finite time limits in which method steps g) and h) are expected to complete.

[0046] In an embodiment, Figure 5 and 6 show that the first reference pattern P1 comprises an increasing curve of acoustic magnitude M and wherein the second reference pattern P2 comprises a decreasing curve of acoustic magnitude M. This embodiment specifies specific parts of acoustic trajectories that represent the process of heating the substance 1 to a boiling phase. In particular, the plurality of processed first sound samples 9, 10 must correlate with the predefined increasing curve of acoustic magnitude M and at a later time the plurality of processed second sound samples 11 , 12 must correlate with the predefined decreasing curve of acoustic magnitude M as shown in Figure 6. So when both correlations with P1 and P2 have been determined, the substance 1 can be considered to have traversed an acoustic trajectory of acoustic magnitude M corresponding to a heating pattern that ends in a boiling phase.

[0047] In a specific embodiment, the increasing curve of the acoustic magnitude M is a straight curve and wherein the decreasing curve of acoustic magnitude M is a straight curve. In this embodiment both the increasing curve and the decreasing curve of acoustic magnitude M are straight lines, reducing correlation complexity and allow for accurate estimation of correlation. In this embodiment, linear correlation techniques (Pearson’s method) can be used. As indicated in Figure 5 and 6, the straight increasing curve for P1 and straight decreasing curve for P2 represent a part of the acoustic magnitude A2 and acoustic magnitude A4 respectively. Furthermore, the straight increasing curve for P1 and straight decreasing curve for P2 may cover different ranges of higher and lower values for the acoustic magnitude M.

[0048] Regarding the time interval Q mentioned earlier, note that in an advantageous embodiment the step of i) defining the time interval Q may comprise determining a duration of the time interval Q based on a slope of the increasing curve of acoustic magnitude M. In this embodiment the duration of the time interval Q in which the method steps g) and h) are expected to complete can be estimated based on the slope of e.g. the first reference pattern P1, i.e. the increasing curve of acoustic magnitude M. For example, a steeper slope of the increasing curve may indicate that a boiling phase will reached quicker, so that correlation with the decreasing curve of acoustic magnitude M is expected sooner, hence shortening the duration or length of the time interval Q. Conversely, a more moderate slope of the increasing curve of acoustic magnitude M would indicate a slower acoustic trajectory to reach a boiling phase and so correlation with the decreasing curve of acoustic magnitude M can be expected to take longer, hence lengthening the duration or length of the time interval Q.

[0049] To achieve increased certainty as to whether a correlation has been found with the second reference pattern P2, and that the boiling phase is detected, an embodiment can be considered wherein the step of f) comparing the plurality of processed second sound samples 11 , 12 to the second reference pattern P2 yields two or more second correlation numbers r2, and wherein the step of h) comprises determining that each of the two or more second correlation numbers r2 is equal to or larger than the second pre-set value, i.e. s2.

[0050] In this advantageous embodiment, a plurality of correlations of the plurality of processed second sound samples 11 , 12 are utilized to firmly establish that the acoustic trajectory followed by the substance 1 matches the second reference pattern P2. So as time progresses, it can be envisaged that newly recorded sound samples are added to the plurality of second sound samples 8, which are subsequently processed and added to the plurality of processed second sound samples 11 , 12. This, in turn, allows two or more plurality of second correlation numbers r2 to be obtained in step f). When each of the second correlation numbers r2 is equal to or larger than the second pre-set value s2 provides stronger evidence that the substance 1 exhibits parts of an acoustic trajectory that matches the second reference pattern P2. Of course, this second reference pattern P2 may be the aforementioned decreasing curve of acoustic magnitude M and in particular a linear / straight decreasing curve.

[0051] Likewise, utilizing a plurality of first correlation numbers r1 can be considered in a manner similar to the plurality of second correlation numbers r2. For example, in an embodiment the step of c) comparing the plurality of processed first sound samples 9, 10 to the first reference pattern P1 yields two or more first correlation numbers r1, and wherein the step of g) then comprises determining that each of the two or more first correlation numbers r1 is equal to or larger than the first pre-set value s1. In this embodiment the plurality of correlations of the plurality of processed first sound samples 9, 10 are utilized to firmly establish that the acoustic trajectory followed by the substance 1 follows the first reference pattern P1. So as time progresses, it can be envisaged that newly recorded sound samples are added to the plurality of first sound samples 7, which are subsequently processed and added to the plurality of processed first sound samples 9, 10. In turn this allows a plurality of first correlation numbers r1 to be obtained in step c). When each of the first correlation numbers r1 is equal to or larger than the first pre-set value s1 provides strong evidence that the substance 1 exhibits an acoustic trajectory that matches the first reference pattern P1.

[0052] Utilizing two or more first and / or second correlation numbers r1, r2 can be advantageous when small disturbances or perturbations of the acoustic trajectory occur during the heating process. For example, a user may decide to stir the substance 1 during the acoustic trajectory of the increasing curve of acoustic magnitude A2 shown in Figure 2 and 5, thereby introducing disturbances during this acoustic trajectory. Likewise, a user may decide to stir the substance 1 during the acoustic trajectory of the decreasing curve of acoustic magnitude A4, thereby introducing disturbances into this particular acoustic trajectory also. By obtaining two or more first correlation numbers r1 and / or two or more second correlation numbers r2 ensures that perturbations / disturbances have less negative impact on the method steps c) and f) for example, so that reliable correlations with the first and second reference patterns P1, P2 remains possible.

[0053] Referring to Figure 6, and step S1 in Figure 3, exemplary embodiments of the plurality of processed first sound samples 9, 10 and the plurality of processed second sound samples 11 , 12 are depicted and can be explained in further detail. In particular, it was mentioned earlier that the acoustic magnitude M along the vertical axes of e.g. Figure 2, 5 and 6 need not represent mere amplitudes of measured sound samples by the acoustic sensor 3, but where the acoustic magnitude M may be construed or interpreted as a generalized magnitude of processed sound samples that is useful analysis.

[0054] For example, in Figure 6 an embodiment is considered wherein the step of b) processing the plurality of first sound samples 7 comprises the step of filtering the plurality of first sound samples, thereby yielding a plurality of filtered first sound samples. It is important to note that a first sound sample of the plurality of first sound samples 7 comprises discrete values measured by the acoustic sensor 3 as indicated by the dotted lines for each time interval Ati to Ate.

[0055] Furthermore, the plurality of filtered first sound samples are not represented in Figure 6 as they involve “minor” processing for each first sound sample recorded over the depicted exemplary time intervals Ati, ... Ate. In an embodiment, a band-pass filter can be used for filtering the plurality of first sound samples 7.

[0056] Next, for each filtered first sound sample of the plurality of filtered first sound samples a Root Mean Square, RMS, value is calculated, thereby yielding a plurality of first RMS values 9 as depicted. So an RMS value 9 is determined for each filtered first sound sample of the plurality of filtered first sound samples, see. e.g. RMS (1) to RMS (6) for each corresponding time interval Ati to Ate.

[0057] The method then continues by calculating a plurality of average values of the plurality of first RMS values 9, thereby yielding a plurality of first RMS average values 10. In this step average values are calculated from the plurality of first RMS values 9. See the exemplary average values RMS(1) to RMS 4-). The plurality of first RMS average values 10 may now be considered to represent the plurality of processed first sound samples 10.

[0058] In analogous manner, the step of e) processing the plurality of second sound samples 8 comprises the steps of filtering the plurality of second sound samples 8, yielding a plurality of filtered second sound samples. Likewise, a second sound sample of the plurality of second sound samples 8 comprises discrete values measured by the acoustic sensor 3 as indicated by the dotted lines for each time interval Atnto AtN. Also, the plurality of filtered second sound samples are not represented in Figure 6 as they involve “minor” processing for each sound sample recorded over the exemplary time intervals Atn, ... AtN. A band-pass filter as mentioned earlier can be used for filtering the plurality of second sound samples 8. Next, a Root Mean Square, RMS, value is calculated of each filtered second sound sample of the plurality of filtered second sound samples, yielding a plurality of second RMS values 11. Thus, for each second sound sample of the plurality of filtered second sound samples, an RMS value 11 is determined as shown, see. e.g. RMS (n) to RMS (N) for each corresponding time interval Atnto IN.

[0059] Subsequently the method continues by calculating a plurality of average values of the plurality of second RMS values 11 , thereby yielding a plurality of second RMS average values 12. Here, average values are calculated from the plurality of second RMS values 11 , see the exemplary average values RMS(n) to RMS n+3). The plurality of second RMS average values 12 may now be considered to represent the plurality of processed second sound samples 12.

[0060] Note that the plurality of first RMS average values 10 and the plurality of second RMS average values 12 each represent an acoustic magnitude M in a generalized way as discussed hereinabove. Furthermore, for method steps c) and f), the first reference pattern P1 and the second reference pattern P2 represent reference patterns for the first and second RMS average values respectively.

[0061] The plurality of first RMS average values 10 and the plurality of second RMS average values 12 are advantageous as these averaged RMS values 10, 12 provide a high degree of smoothing to the acoustic trajectory followed by the substance 1 during heating and as such allows for increased reliability and accuracy when comparing the first and second RMS average values 10, 12 with respect to the first and second reference patterns P1, P2 respectively.

[0062] The process of calculating the plurality of RMS average values can be explained in further detail based on Figure 6. In particular, the step of calculating the plurality of average values of the plurality of first RMS values 9 may comprise selecting a plurality of first subsets 13 each of which first subset comprises first RMS values of the plurality of first RMS values 9. That is, from the plurality of first RMS values 9, see e.g. RMS (1) to RMS (6), two or more of these first RMS values 9 are selected and “collected” in a first subset of the plurality of first subsets 13. In Figure 6 this is exemplified by the dotted line wherein each first subset 13 comprises three selected first RMS values 9.

[0063] Subsequently, an average value of each first subset of the plurality of first subsets 13 is calculated, thus yielding the plurality of first RMS average values 10. See e.g. 7?MS(1) to 7?MS(4) each of which is calculated from a corresponding first subset 13 as depicted.

[0064] In similar manner, calculating the plurality of average values of the plurality of second RMS values 11 may comprise selecting a plurality of second subsets 14 each of which second subset comprises second RMS values of the plurality of second RMS values 1 1 , and calculating an average value of each second subset of the selected plurality of second subsets 14, thereby yielding the plurality of second RMS average values 12. See e.g. see RMS(n) to 7?MS(n+3) each of which is calculated from a corresponding second subset 14 as depicted.

[0065] In this embodiment a structured and convenient approach is taken to arrive at the plurality of first and second RMS average values 10 to 12 for reliable and accurate correlation with respect to the first and second reference patterns P1, P2. An exemplary embodiment can be envisaged for ensuring that the plurality of first and second subsets 13, 14 are populated in optimal manner. For example, Figure 6 shows an embodiment wherein the step of selecting the plurality of first subsets 13 comprises defining a first selection window 15 that determines a size of each first subset 13. Here, the size of each first subset 13 refers to the number of first RMS values 9 contained in each first subset 13. This first selection window 15 is then “moved” (in temporal sense) along the plurality of first RMS values 9 obtained for the time intervals Ati to Ate as indicated.

[0066] As time further progresses, selecting the plurality of second subsets 14 is achieved by a second selection window 16 determining a size of each second subset 14 and moving (in temporal sense) the second selection window 16 along the plurality of second RMS values 11 obtained for the time intervals Atnto AtN as indicated. So, by using the first and second selection windows 15, 16 ensures that each first subset 13 and each second subset 14 comprises a collection of consecutive first and second RMS values 9, 11 , respectively, as time progresses and sound samples are recorded and processed accordingly.

[0067] Another way to look at such selection windows is that the first selection window 15 in Figure 6 selects a number of first RMS values 9 obtained for the time interval Ate and previous / historic time intervals Ats, At4 prior to the time interval Ate. Similarly, the second selection window 16 may be seen as selecting a number of second RMS values 11 obtained for the later time interval AtN and previous / historic time intervals AtN-i, AtN-2 thereof prior to the time interval AtN.

[0068] It is interesting to note that selection windows need not be identical. For example, in an advantageous embodiment the size of the first and second selection windows 15, 16 may be different. This embodiment allows differentiation between the number of first and second RMS values 9, 1 1 to consider when calculating average values thereof. For example, the acoustic trajectory corresponding to the decreasing curve of acoustic magnitude A4 may be analysed with e.g. increased accuracy or reliability by using a larger second selection window 16, thus increasing a size of second subsets 14 and therefore a larger number of second RMS values 11 in each second subset 14. Similar considerations apply to the first selection window 15, of which a size can be chosen based on requirements for determining the plurality of first RMS average values 10.

[0069] The method as explained above allows accurate and reliably detection as to whether a substance 1 in a cooking utensil 2 has reached a boiling phase when the substance 1 undergoes heating. In light of Figure 1 , a further aspect of the present invention relates to a cooking utensil 2 for heating the substance 1 in the cooking utensil 2, wherein the cooking utensil 2 comprises the acoustic sensor 3, the processing system 4, and the transmitter 5. The processing system 4 is communicatively connected to the acoustic sensor 3 and the transmitter 5, and wherein the processing system 4 is configured to execute the method steps a) to h) as explained in detail above. When the boiling phase of the substance 1 is determined when the at least one first correlation number r1 is equal to or larger than the first pre-set value s1, and the at least one second correlation number r2 is equal to or larger than the second pre-set value s2, then the processing system 4 is configured to activate the transmitter 5 to transmit a signal to the heat source 7 (e.g. via the cooking hob 6) for regulating heat input to the substance 1 . By virtue of executing the method steps a) to h) by the processing system 4, the cooking utensil 2 is able to autonomously detect when the substance 1 reaches a boiling phase and adjust the heat input accordingly.

[0070] Further embodiments are conceivable wherein the processing system 4 activates the transmitter 5 to transmit a signal for shutting down the heat source 7 in case the time interval Q has been defined but wherein the completion of method step h) relative to step g) has not been achieved within this time interval Q. Likewise, embodiments are conceivable wherein the processing system 4 activates the transmitter 5 to transmit a signal for shutting down the heat source 7 in case the start time interval Qs has been defined but wherein completion of step g) within this start time interval Qs has not yet occurred, i.e. wherein the at least one first correlation number r1 has not yet matched or exceeded the first pre-set value s1 within the start time interval Qs.

[0071] In view of the above, the present invention can now be summarized by the following embodiments:

[0072] Embodiment 1. A method for determining a boil phase of a substance (1) heated by a cooking utensil (2), the cooking utensil (2) comprising an acoustic sensor (3), comprising the steps of: a) recording a plurality of first sound samples (7) measured by the acoustic sensor (3) as the substance (1) is being heated by the cooking utensil (2); b) processing the plurality of first sound samples (7), yielding a plurality of processed first sound samples; c) comparing the plurality of processed first sound samples to a first reference pattern (P1), yielding at least one first correlation number (r1); and further comprising the subsequent steps of d) recording a plurality of second sound samples (8) measured by the acoustic sensor (3); e) processing the plurality of second sound samples (8), yielding a plurality of processed second sound samples; f) comparing the plurality of processed second sound samples to a second reference pattern (P2), yielding at least one second correlation number (r2); and confirming a boil phase of the substance (1) by the steps of g) determining that the at least one first correlation number (r1) is equal to or larger than a first pre-set value (s1), and h) determining that the at least one second correlation number (r2) is equal to or larger than a second pre-set value (s2).

[0073] Embodiment 2. The method according to embodiment 1 , further comprising the step of i) defining a time interval (Q) in which completion of method step h) relative to step g) must occur for confirming the boil phase of the substance (1). Embodiment 3. The method according to embodiment 1 or 2, wherein first reference pattern (P1) comprises an increasing curve of acoustic magnitude (M) and wherein the second reference pattern (P2) comprises a decreasing curve of acoustic magnitude (M).

[0074] Embodiment 4. The method according to embodiment 3, wherein the increasing curve of acoustic magnitude (M) is a straight curve and wherein the decreasing curve of acoustic magnitude (M) is a straight curve.

[0075] Embodiment 5. The method according to embodiment 2 and embodiments 3 or 4, wherein the step of i) defining the time interval (Q) comprises determining a duration of the time interval (Q) based on a slope of the increasing curve of acoustic magnitude (M).

[0076] Embodiment 6. The method according to any of embodiments 1-5, wherein the step of f) comparing the plurality of processed second sound samples to the second reference pattern (P2) yields two or more second correlation numbers (r2); and wherein the step of h) comprises determining that each of the two or more second correlation numbers (r2) is equal to or larger than the second pre-set value.

[0077] Embodiment 7. The method according to any of embodiments 1-6, wherein the step of c) comparing the plurality of processed first sound samples to the first reference pattern (P1) yields two or more first correlation numbers (r1), and wherein the step of g) comprises determining that each of the two or more first correlation numbers (r1) is equal to or larger than the first pre-set value.

[0078] Embodiment 8. The method according to any of embodiments 1-7, wherein the step of b) processing the plurality of first sound samples (7) comprises the steps of: filtering the plurality of first sound samples (7), yielding a plurality of filtered first sound samples; calculating a Root Mean Square, RMS, value of each sample of the plurality of filtered first sound samples, yielding a plurality of first RMS values (9); and calculating a plurality of average values of the plurality of first RMS values (9), yielding a plurality of first RMS average values (10) representing the plurality of processed first sound samples; and wherein the step of e) processing the plurality of second sound samples (8) comprises the steps of: filtering the plurality of second sound samples (8), yielding a plurality of filtered second sound samples; calculating a Root Mean Square, RMS, value of each sample of the plurality of filtered second sound samples, yielding a plurality of second RMS values (11); and calculating a plurality of average values of the plurality of second RMS values (11), yielding a plurality of second RMS average values (12) representing the plurality of processed second sound samples.

[0079] Embodiment 9. The method according to claim 8, wherein the step of calculating the plurality of average values of the plurality of first RMS values (9) comprises selecting a plurality of first subsets (13) each of which first subset comprises first RMS values of the plurality of first RMS values (9), and calculating an average value of each first subset of the selected plurality of first subsets (13), yielding the plurality of first RMS average values (10); and wherein calculating the plurality of average values of the plurality of second RMS values (11) comprises selecting a plurality of second subsets (14) each of which second subset comprises second RMS values of the plurality of second RMS values (11), and calculating an average value of each second subset of the selected plurality of second subsets (14), yielding the plurality of second RMS average values (12).

[0080] Embodiment 10. The method according to embodiment 9, wherein the step of selecting the plurality of first subsets (13) comprises defining a first selection window (15) determining a size of each first subset, and moving the first selection window (15) along the plurality of first RMS values (9); and wherein the step of selecting the plurality of second subsets (14) comprises defining a second selection window (16) determining a size of each second subset, and moving the second selection window (16) along the plurality of second RMS values (11).

[0081] Embodiment 11. The method according to embodiment 10, wherein the size of the first and second selection windows (15, 16) are different.

[0082] Embodiment 12. A cooking utensil (2) for heating a substance (1) in the cooking utensil (2) by a heating source (7), comprising an acoustic sensor (3), a processing system (4), and a transmitter (5), wherein the processing system (4) is communicatively connected to the acoustic sensor (3) and the transmitter (5), and wherein the processing system (4) is configured to: execute the method of any of embodiments 1-11 , and when a boiling phase of the substance (1) is determined, activate the transmitter (5) to transmit a signal to the heat source (7) for regulating heat input to the substance (1).

Claims

CLAIMS1 . A method for determining a boil phase of a substance (1) heated by a cooking utensil (2), the cooking utensil (2) comprising an acoustic sensor (3), comprising the steps of: a) recording a plurality of first sound samples (7) measured by the acoustic sensor (3) as the substance (1) is being heated by the cooking utensil (2); b) processing the plurality of first sound samples (7), yielding a plurality of processed first sound samples; c) comparing the plurality of processed first sound samples to a first reference pattern (P1), yielding at least one first correlation number (r1); and further comprising the subsequent steps of d) recording a plurality of second sound samples (8) measured by the acoustic sensor (3); e) processing the plurality of second sound samples (8), yielding a plurality of processed second sound samples; f) comparing the plurality of processed second sound samples to a second reference pattern (P2), yielding at least one second correlation number (r2); and confirming a boil phase of the substance (1) by the steps of g) determining that the at least one first correlation number (r1) is equal to or larger than a first pre-set value (s1), and h) determining that the at least one second correlation number (r2) is equal to or larger than a second pre-set value (s2).

2. The method according to claim 1 , further comprising the step of i) defining a time interval (Q) in which completion of method step h) relative to step g) must occur for confirming the boil phase of the substance (1).

3. The method according to claim 1 or 2, wherein first reference pattern (P1) comprises an increasing curve of acoustic magnitude (M) and wherein the second reference pattern (P2) comprises a decreasing curve of acoustic magnitude (M).

4. The method according to claim 3, wherein the increasing curve of acoustic magnitude (M) is a straight curve and wherein the decreasing curve of acoustic magnitude (M) is a straight curve.

5. The method according to claim 2 and claim 3 or 4, wherein the step of i) defining the time interval (Q) comprises determining a duration of the time interval (Q) based on a slope of the increasing curve of acoustic magnitude (M).

6. The method according to any of claims 1-5, wherein the step of f) comparing the plurality of processed second sound samples to the second reference pattern (P2) yields two or more second correlation numbers (r2); and wherein the step of h) comprises determining that each ofthe two or more second correlation numbers (r2) is equal to or larger than the second pre-set value.

7. The method according to any of claims 1-6, wherein the step of c) comparing the plurality of processed first sound samples to the first reference pattern (P1) yields two or more first correlation numbers (r1), and wherein the step of g) comprises determining that each of the two or more first correlation numbers (r1) is equal to or larger than the first pre-set value.

8. The method according to any of claims 1 -7, wherein the step of b) processing the plurality of first sound samples (7) comprises the steps of: filtering the plurality of first sound samples (7), yielding a plurality of filtered first sound samples; calculating a Root Mean Square, RMS, value of each sample of the plurality of filtered first sound samples, yielding a plurality of first RMS values (9); and calculating a plurality of average values of the plurality of first RMS values (9), yielding a plurality of first RMS average values (10) representing the plurality of processed first sound samples; and wherein the step of e) processing the plurality of second sound samples (8) comprises the steps of: filtering the plurality of second sound samples (8), yielding a plurality of filtered second sound samples; calculating a Root Mean Square, RMS, value of each sample of the plurality of filtered second sound samples, yielding a plurality of second RMS values (11); and calculating a plurality of average values of the plurality of second RMS values (11), yielding a plurality of second RMS average values (12) representing the plurality of processed second sound samples.

9. The method according to claim 8, wherein the step of calculating the plurality of average values of the plurality of first RMS values (9) comprises selecting a plurality of first subsets (13) each of which first subset comprises first RMS values of the plurality of first RMS values (9), and calculating an average value of each first subset of the selected plurality of first subsets (13), yielding the plurality of first RMS average values (10); and wherein calculating the plurality of average values of the plurality of second RMS values (11) comprises selecting a plurality of second subsets (14) each of which second subset comprises second RMS values of the plurality of second RMS values (11), and calculating an average value of each second subset of the selected plurality of second subsets (14), yielding the plurality of second RMS average values (12).

10. The method according to claim 9, wherein the step of selecting the plurality of first subsets (13) comprises defining a first selection window (15) determining a size of each first subset, and moving the first selection window (15) along the plurality of first RMS values (9); and wherein the step of selecting the plurality of second subsets (14) comprises defining a second selection window (16) determining a size of each second subset, and moving the second selection window (16) along the plurality of second RMS values (11).11 . The method according to claim 10, wherein the size of the first and second selection windows (15, 16) are different.

12. A cooking utensil (2) for heating a substance (1) in the cooking utensil (2) by a heating source (7), comprising an acoustic sensor (3), a processing system (4), and a transmitter (5), wherein the processing system (4) is communicatively connected to the acoustic sensor (3) and the transmitter (5), and wherein the processing system (4) is configured to: execute the method of any of claims 1-11 , and when a boiling phase of the substance (1) is determined, activate the transmitter (5) to transmit a signal to the heat source (7) for regulating heat input to the substance (1).

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