Method and assembly for evaluating an eggshell temperature

Abstract

A method and a sensor assembly for measuring and evaluating an egg-shell temperature, in particular of poultry eggs in a hatching environment, wherein the method comprises the steps of providing a sensor in direct contact with an egg, the sensor being configured to non-invasively measure a temperature of an eggshell of said egg, and the sensor measuring said eggshell temperature.

Description

METHOD AND ASSEMBLY FOR EVALUATING AN EGGSHELL TEMPERATUREField

[0001] The present invention generally relates to a method and an assembly for evaluating an eggshell temperature, in particular of poultry eggs.Background

[0002] It is generally known that incubation of poultry eggs, in particular chicken eggs, is performed in two steps. In a first step, typically during the first 18 days of incubation, eggs are placed in setter trays inside a setter machine. The setter machine can include a turning mechanism configured to turn the eggs at regular intervals. Thereto, the eggs are placed at fixed locations on the setter tray. In a second step, the eggs may be transferred from the setter trays into hatching baskets which may then be placed in a hatching machine, which is generally done for chicken eggs more or less from day 16, 17 or 18 to day 21 of the incubation process. For other poultry eggs, this timing can be adapted in function of the respective incubation and hatching process. Alternatively, eggs may be transferred from the setter trays to an on-farm hatching system, where eggs may be randomly placed on the ground for hatching. Contrary to the setter trays, eggs do not have fixed locations in such a hatching basket nor necessarily in an on- farm hatching system since turning of eggs is not required anymore.

[0003] It is also generally known that environmental parameters within a setter, as well as in a hatching system, are of the utmost importance for the incubation process of the eggs. Said environmental parameters, such as ambient air temperature, CO2 level, and / or humidity, are therefore well controlled in a relatively precise way to meet the needs of the poultry embryos in the eggs and to enhance the incubation process.

[0004] One parameter that can help in evaluating conditions to which the embryo is exposed is the eggshell temperature. Measuring eggshell temperature in a setter has been known for many years. However, techniques to do so in a setter cannot easily be transferred to a hatching system, nor to on-farm hatching, since eggs in a hatchingbasket or in a farm can lie randomly around, which can seriously complicate measurement of an eggshell temperature. To cope with this difficulty, it is known to maintain eggs in setter trays and to place the setter trays on the ground in an on-farm system. Alternatively, a small selection of eggs is placed in dedicated places or holders in the on-farm hatching system such that an eggshell temperature of said selection of eggs can be measured, while a majority of eggs lie randomly around. Said measurement on the selection of eggs can be done with a contact sensor or a contact- free sensor. On top of that, application of a sensor configured to measure eggshell temperature can be challenging, in particular in an automated transfer of eggs from setter trays to hatching baskets. Manual application of sensors, for example on a selection of eggs in an on-farm hatching system, may be relatively time-consuming, in particular in a hatching system with (semi-)automated transfer of eggs from a setter to the hatching system. Further, due to potential hatching of chicks in the hatching basket, eggshell temperature measurements in a hatching basket can become affected or even unreliable because of dirt from recently hatched chicks interfering with sensor measurements, because of eggs being shifted by the hatched chicks and / or because of hatched chicks crawling over unhatched eggs. This is also true for on-farm hatching. It is therefore a challenge to provide a reliable eggshell temperature measurement during the last portion of the incubation process, in particular during the hatching process.

[0005] Outside a commercial set-up, for example in laboratories, it is known to measure eggshell temperature via a sensor device which is configured to be clipped on an egg such that the egg is clamped between two arms of the sensor device. Alternatively, a sensor configured to measure an eggshell temperature can be glued to an egg. However, such attached or glued sensor devices can be considered as semi-invasive measuring techniques since it has been shown that the sensor can cover part of the available surface of the eggshell, block some of the pores for gas exchanges and restrict embryos from pipping around while emerging from the shell, thus influencing biological processes of the incubation and / or hatching.of the Invention

[0006] It is therefore an aim of the present invention to solve or at least alleviate one or more of the above-mentioned problems. In particular, the invention aims at providing an improved method for evaluating eggshell temperature which can be applied in different environments, in particular in, but not limited to, a hatching system.

[0007] To this aim, according to a first aspect of the invention, there is provided a method comprising a plurality of steps. A sensor is provided in direct contact with an egg, in particular with an external side of the eggshell, the sensor being configured to non-invasively measure a temperature of an eggshell of said egg. The non-invasive measurement implies the use of a sensor which only makes external contact with an eggshell, such that the hatching process is not influenced nor disturbed by the contact of the sensor with the eggshell. The sensor measures said eggshell temperature. A current pulse is then generated in said sensor, for example by applying a current to said sensor, or alternatively, by applying a voltage to said sensor thus inducing a current. Thereto, the sensor can for example be a thermal property sensor such as a transient plane source sensor, which is configured to measure thermal properties of a material, such as thermal conductivity, thermal diffusivity, volumetric specific heat or thermal effusivity. The sensor can include an electrically conductive layer. Said electrically conductive layer may be in direct contact with said eggshell or may be covered by a protective but non-insulating layer which may be in direct contact with the eggshell. The current pulse can be generated in said electrically conductive layer, either by applying a current to said layer or by providing a voltage to said layer inducing a current. In a next step, the sensor then senses a temperature - induced change in resistance, which is caused by the current pulse applied to or induced in said sensor causing a heating of the electrically conductive layer due to Joule heating. Said temperature - induced change in resistance may for example be measured by a voltage measurement or, alternatively, by a current measurement. Said change in resistance is dependent on heat exchange with an environment of the sensor, so is dependent on the thermal properties of the material in contact with the electrically conductive layer, in particular of said egg. Then information about contact between said sensor and said egg is derived from the temperature-induced change in resistance, since thermal properties of an egg, in particular of the eggshell, are known.In particular, the sensor sensing a relatively low change in resistance due to a relatively low change in temperature caused by the current pulse, points to a relatively good contact between said sensor and said egg, since an increase in temperature caused by the current pulse may at least partially be dissipated by the egg thanks to said relatively good contact between said sensor and said egg. In the opposite case, the sensor sensing a relatively high change in resistance due to a relatively high change in temperature caused by the current pulse, points to a relatively bad contact, or even loss of contact, between said sensor and said egg, since an increase in temperature caused by the current pulse may not be dissipated by the egg or eggshell. In a further step, said measured eggshell temperature may be evaluated based on said derived contact information. In particular, if the contact information points to a relatively good contact between the sensor and the egg, the measured temperature may be evaluated as being a relatively reliable eggshell temperature, whereas, if the contact information points to a relatively bad contact or a loss of contact, the measured temperature may be evaluated as being a relatively unreliable eggshell temperature. Such a method can allow measurement of eggshell temperature outside a setter, in particular during the final hatching period, in a hatcher or in an on-farm hatching process, before chicks come out of the eggs.

[0008] The step of measuring said eggshell temperature may include generating a further current pulse in said sensor, said further current pulse being below a selfheating current threshold for causing heating. In other words, the step of measuring said eggshell temperature may be performed using a resistance temperature detector configured to measure temperature via a relatively stable and accurate resistance vs temperature relationship. Resistance can be measured via a voltage measurement when a current is applied to the sensor, in particular to the electrically conductive layer. Alternatively, when a voltage is applied to the sensor to induce a current, resistance can be measured via a current measurement. The step of measuring said eggshell temperature by generating a further current pulse, which is relatively small, in said sensor may preferably be performed before the step of generating a current pulse, which is relatively high and above said self-heating current threshold, in the electrically conductive layer. In this way, a single sensor may be used for temperature measurement via said resistance vs temperature relationship as well as for measuring a thermal contact quality. By including a sensor in which the change in resistance ismeasured by the same element as the element which may be heated through Joule heating, the sensor can be made relatively small and cost-effective.

[0009] The method can further comprise the step of adjusting environmental parameters of a hatching environment based on the evaluated eggshell temperature. In case of a relatively reliably measured eggshell temperature, an ambient air temperature can for example be adjusted such that a desired eggshell temperature can be reached. Other environmental parameters may be adjusted, such as ambient air humidity, CO2, lighting, sound, ventilation, etcetera, such that a desired hatching environment and / or eggshell temperature can be reached, which can influence on a timing of hatching and provide a relatively narrow hatching window. This is in particular applicable in a hatching machine, but ambient air temperature and other parameters may also be adjustable in an on-farm setting.

[0010] The method can further comprise the step of determining a hatching stage of said egg based on said derived contact information and on the evaluated egg-shell temperature. Said derived contact information can for example indicate a loss of contact between the sensor and the egg, which may, but need not, point to a hatching of a chick out of its egg. Said derived contact information may alternatively indicate a relatively good contact between the sensor and the egg, which may, in combination with a relatively reliable eggshell temperature, and potentially with a timing of the eggshell temperature measurement, provide an indication of pre-hatching stage, such as a rest phase, an internal pipping phase, a preparation phase for hatch. When used outside a hatching system, for example during an entire incubation process, the method can include the step of determining any embryonic stage based on said derived contact information and on the evaluated egg-shell temperature.

[0011] The method can preferably further comprise the step of determining an ambient air temperature. The step of determining a hatching stage of said egg can then additionally be based on said determined ambient temperature. Said ambient air temperature may be an air temperature in a vicinity of the egg and / or may be an air temperature within a hatching machine. In particular, a relationship, for example a difference, between said determined ambient temperature and said eggshell temperature may be determined, which may help in determining a hatching stage. Asan example, for a controlled ambient air temperature, the measured eggshell temperature may not remain constant, which may indicate that the embryo has gone into a rest phase for a decrease of eggshell temperature or that the embryo is preparing to hatch for an increase of eggshell temperature.

[0012] When a hatching stage has been determined, the method can further comprise the step of adjusting environmental parameters of a hatching environment based on the determined hatching stage. As an example, an ambient air temperature, and / or a level of CO2 may be adjusted, for example by providing more or less ventilation. Other adjustable parameters may include a degree of humidity, light, or other known parameters. These parameters need not be kept constant but can be adapted to the needs of the eggs or hatched chicks depending on the determined hatching stage. As an example, by controlling an ambient air temperature, an eggshell temperature may be allowed to deviate, in particular to decrease, when the egg is determined to be in a resting phase, thus preventing a heating of the ambient air as a compensation for a lower eggshell temperature. The same is valid for the opposite case: by controlling an ambient air temperature, an eggshell temperature may be allowed to deviate, in particular to increase, when the egg is determined to be preparing for hatch, thus preventing a cooling of the ambient air as a compensation for a higher eggshell temperature.

[0013] According to a further aspect of the invention, there is provided a sensor assembly having the features as claimed in claims 7 to 10. In particular, the sensor assembly includes a sensor configured to measure an eggshell temperature. The sensor may be a dedicated temperature sensor or may be configured to measure temperature via for example a voltage measurement. The sensor may for example be a resistive temperature detector. The sensor includes an electrically conductive layer. The assembly further includes a current pulse generator configured to generate a current pulse in said sensor, in particular in said electrically conductive layer. The sensor is further configured to sense a temperature - induced change in resistance. The electrically conductive layer may preferably be a resistor. The sensor assembly further includes at least one egg receiving portion configured to receive an egg. In an inventive way, the electrically conductive layer of the sensor is included in the at leastone egg receiving portion such that an egg lying on said egg receiving portion is at least partially in direct contact with the sensor.

[0014] Said at least one egg receiving portion may for example be at least partially concave such that an egg can lie on said at least partially concave portion in a relatively stable way. Alternatively, the at least one egg receiving portion may be substantially flat. In that case, the at least one egg receiving portion may, but need not, include a rim at least partially surrounding the substantially flat portion, to prevent an egg from rolling away. Said rim may have a bevelled inner side to improve support of an egg on the egg receiving portion.

[0015] The sensor assembly can for example further include a mat or a pad including a plurality of said egg receiving portions, the mat or pad being configured to be laid in a hatcher basket. Each of said plurality of egg receiving portions may then include a respective electrically conductive layer. In this way, eggs can be laid randomly in said hatcher basket, while at least a number of said eggs will be lying on said egg receiving portions and will thus be in direct contact with the sensor. Thanks to the contact information between the egg and the sensor, a random distribution of eggs in a hatcher basket can thus be maintained, which simplifies transfer of eggs from a setter tray to a hatcher basket, while an egg-shell temperature measurement and evaluation becomes possible such that only measurements with positive contact information can be taken into account. Moreover, such a mat or pad can be easily added and laid down in existing hatcher baskets such that no new hatcher baskets need to be bought. Such a mat or pad may include substantially flat egg receiving portions or at least partially concave egg receiving portions. Alternatively, the sensor assembly may have a spoonlike shape including a single egg receiving portion. A plurality of said sensor assemblies can then be inserted into a hatcher basket, for example via an opening in an upstanding side wall of the hatcher basket.

[0016] The sensor assembly may further include a protective layer configured to protect the electrically conductive layer, in particular against dirt and dust, to avoid any short circuit. The protective layer may further be configured to be in direct contact with an egg lying on said egg receiving portion. A material of said protective layer is chosen such that the protective layer is configured to be thermally conductive, i.e. to transferheat, while being electrically isolating. When a current pulse is generated in said electrically conductive layer, a Joule heating due to said current pulse is transferred through said protective layer to said eggshell in contact with the sensor. To compensate for said protective layer, a current pulse may be applied during a longer time than without a protective layer, rather than generating a current pulse of a higher intensity.

[0017] According to a further aspect of the invention, there is provided a hatcher basket having the features of claim 11 . The hatcher basket comprises a basket bottom and at least one upstanding side wall surrounding said basket bottom. A sensor assembly as previously described is integrated into said basket bottom. The hatcher basket can provide one or more of the above-mentioned advantages.

[0018] According to a further aspect of the invention, there is provided a computer- implemented method having the features of claim 12. Many of the above-mentioned method steps can be embodied as computer-implemented method steps. The computer-implemented method can provide one or more of the above-mentioned advantages.

[0019] According to a further aspect of the invention, there is provided controller comprising at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the controller to perform the method as described above. There is also provided a computer program product comprising computer-executable instructions for performing the method when the program is run on a computer, as well as a computer readable storage medium comprising computerexecutable instructions for performing the method when the program is run on a computer. Said controller may at least partially be included in the sensor assembly. Alternatively, the controller may be a remote controller and the sensor assembly may include communication means configured to send data to said remote controller. In particular, the controller may at least partially be a cloud-based controller.

[0020] The present invention will be further elucidated with reference to figures of exemplary embodiments. Corresponding elements are designated with corresponding reference signs.Briefof the

[0021] Fig. 1 a and 1 b show a perspective view of a preferred embodiment of a sensor assembly, with and without eggs respectively, according to an aspect of the invention;

[0022] Fig. 2a and 2b show a perspective view of further embodiments of said sensor assembly;

[0023] Fig. 3a - 3c show a top view and perspective views on a hatcher basket including the sensor assemblies of Fig. 1a or 2a;

[0024] Fig. 4 represents a flowchart of a preferred embodiment of the method according to an aspect of the invention;

[0025] Fig. 5 shows a graph illustrating how contact information between the sensor and the egg is derived according to the present invention;

[0026] Fig. 6 shows a graph representing a potential application of the last step of the method of Figure 4; and

[0027] Fig. 7 shows a computing system suitable for performing various steps of the method of Figure 4.Detailed Description of Embodiments

[0028] Figures 1 a and 1 b show a perspective view of a preferred embodiment of a sensor assembly 1 , with and without eggs 2 respectively, according to an aspect of the invention. The eggs can for example be poultry eggs during incubation and / or hatching. The sensor assembly 1 can include a main body 1 a. In the present embodiment, the main body 1 a has a substantially elongated shape. The sensor assembly 1 can further include a handle 4 connected to said main body 1 a and configured to hold and / or manipulate the sensor assembly 1. The sensor assembly 1 , in particular said main body 1 a of said sensor assembly 1 , includes at least one egg receiving portion 3 configured to receive an egg 2. In the present embodiment, the sensor assembly 1includes four egg receiving portions 3 which are substantially in line with each other. Said at least one egg receiving portion 3 can for example, but need not, be at least partially concave. The egg receiving portion 3 can for example include a substantially egg-shaped edge or rim 3a configured to at least partially surround an egg to retain said egg on the egg receiving portion 3. The egg receiving portion 3 can be embodied as a recess in the main body 1 a of the sensor assembly 1. Said recess can be substantially egg-shaped and can preferably be smaller than a regular size of a poultry egg. Alternatively, the egg receiving portion can be level with said main body 1 a of the sensor assembly, in which case the surrounding edge or rim may protrude from the sensor assembly. The sensor assembly 1 further comprises a sensor 5 configured to measure an eggshell temperature. The sensor 5 includes an electrically conductive layer 6. The electrically conductive layer 6 of the sensor 5 is included in the at least one egg receiving portion 3 such that an egg 2 lying on said egg receiving portion 3 is at least partially in direct contact with the sensor 5. The sensor assembly 1 further includes a current pulse generator (not shown) configured to generate a current pulse in said sensor 5, in particular in said electrically conductive layer 6. The sensor 5 is further configured to sense a temperature - induced change in resistance.

[0029] Fig. 2a and 2b show a perspective view of further embodiments of said sensor assembly T, 1”. Said sensor assemblies T, 1” differ from the preceding sensor assembly 1 in that the main body 1a is shorter along a longitudinal direction of the assembly and / or has fewer egg receiving portions 3, in particular two, respectively three egg receiving portions 3. A further difference lies in the shape of the handle 4, 4’, 4”. In both embodiments, the handle includes three portions: a first portion 4a, 4’a, 4”a directly attached to the main body 1 a, 1 ’a, 1”a of the sensor assembly 1 , T, 1”, a grip 4c configured to be gripped by a user and a second portion 4b, 4’b, 4”b connecting said first portion 4a, 4’a, 4”a to said grip 4c. Said grip 4c preferably extends substantially transversely to the longitudinal extension of the sensor assembly. In both embodiments, the first portion 4a, 4’a, 4”a makes an angle with the main body 1 a, 1 ’a, 1 ”a, which is preferably an obtuse angle. The first portion 4a, 4’a, 4”a further makes an angle with the second portion 4b, 4’b, 4”b. In the sensor assembly 1 shown in Figures 1 a, 1 b, the first portion 4a of the handle 4 is substantially plate-like, while said first portion 4’a, 4”a of the handle 4’, 4” of the sensor assembly T, 1 ” shown in Figures 2a and 2b is tube-like. The second portion 4b, 4’b, 4”b is tube-like or beam-like in bothcases. Said first portion 4a, 4’a, 4”a may be fixedly attached to said main body 1 a, as shown in Figures 1 a, 1 b, or may be hingedly and / or releasably attached to said main body T, 1”, for example via a click connection or via any other known releasable connection.

[0030] Figures 3a - 3c show a top view (Figure 3a) and perspective views (Figures 3b - 3c) on (part of) a hatcher basket 10 including the sensor assemblies of Fig. 1 a, or further embodiments of sensor assemblies (in Figure 3c). A hatcher basket 10 comprises a basket bottom 11 and at least one upstanding side wall 12 surrounding said basket bottom 11. When eggs are transferred from a setter tray, in which said eggs have fixed positions to allow turning of eggs, to a hatcher basket 10, the eggs are laid in a random way on the basket bottom 11. A hatcher basket 10 having a substantially rectangular shape, as shown in Figure 3a, generally includes four upstanding side walls 12, one along each side of the basket 10. Said basket bottom 11 and / or said at least one upstanding side wall 12 can generally comprise a plurality of openings 13, such as through-holes 13a and / or elongated slits 13b to allow air circulation in said basket 10. The sensor assemblies 1 , T, 1” may advantageously be configured such that said sensor assemblies are insertable via one of said openings 13, preferably via one of said plurality of slits 13b, included in said at least one upstanding side wall 12. Thereto, a width, and additionally a thickness, of the main body 1 a of the sensor assembly may be smaller than a length, respectively a width, of said slits 13b such that the main body 1 a can be inserted or slid into the hatcher basket 10 via said slit 13b. The sensor assembly 1 , T, 1” can be inserted into said slit 13b until the second portion 4b, 4’b, 4”b of the handle 4, 4’, 4” extends through said slit 13b. The second portion is preferably shaped such that said second portion is rotatable within said slit 13b. This rotation can allow to pass the sensor assembly under eggs lying on the basket bottom 11 such that eggs can be received in the egg receiving portions. After hatching of the eggs, the sensor assemblies can be withdrawn from the hatcher basket 10 by rotating said assemblies over more or less a quarter turn such that the main body 1 a can be retracted via the slit. The grip 4c, which is preferably mounted transversely to the second portion of the handle, can prevent the sensor assembly from entirely passing through the slit 13b when the sensor assembly is turned in a position such that the egg receiving portions 3 are substantially in parallel with the basket bottom 11 . In Figure 3c, the hatcher basket 10 is shown without a frontupstanding side wall, just for illustration purposes. A variety of sensor assemblies is shown, of which some have a tube-like second handle portion, as shown in Figures 2a and 2b, and others have a plate-like second handle portion, as shown in Figures 1a and 1 b. The sensor assemblies can have a predetermined number of egg receiving spaces, depending on a size of the hatcher basket 10. A sensor assembly according to one of the embodiments as shown can provide the advantage that eggs can be transferred to said hatcher basket 10 as is usually done and that the sensor assembly can be inserted at least partially into the hatchet basket 10 when the eggs are already lying in the hatcher basket. In this way, the sensor assembly can be used in combination with existing hatcher baskets.

[0031] Alternatively, a sensor assembly may be integrated into a basket bottom 11 of a dedicated hatcher basket 10. Still alternatively, one or more sensors may be included in a mat configured to be laid on a basket bottom 11 of a hatcher basket. Such a mat may include a plurality of said egg receiving portions. In that case, a hatcher basket can also be retrofitted with said mat, but only before eggs are being transferred into the hatcher basket.

[0032] Figure 4 represents a flowchart of a preferred embodiment of the method according to an aspect of the invention. In a first step 100, a sensor is provided in direct contact with an egg. The sensor is configured to non-invasively measure a temperature of an eggshell of said egg. The egg can for example loosely lie on the sensor such that there is no perturbation of internal process within the egg, as can be the case when an egg is clamped between arms of a sensor. In a next step, the sensor measures an eggshell temperature. In a preferred embodiment of the method, this eggshell temperature measurement can be performed using a resistance thermometer. A relatively small current pulse can be generated in an electrically conductive layer of the sensor in step 110, the current pulse remaining below a selfheating current threshold for causing heating of said electrically conductive layer. As an example, a current pulse of around 1 mA may be given during for example 0.1 seconds. Other current and / or timing values are possible as well. In a further step 120, an eggshell temperature may be derived from a resistance measurement by the sensor. In a next step 130, a current pulse is generated in the electrically conductive layer causing the electrically conductive layer to heat due to Joule heating. As anexample, a current pulse of around 35 mA may be given during for example 2 seconds. Other current and / or timing values are possible as well. In a next step 140, the sensor then senses a temperature - induced change in resistance, which is caused by the current pulse applied to said sensor causing a heating of the electrically conductive layer due to Joule heating. Steps 110 - 120 are preferably performed before steps 130 - 140 when a same sensor is used for both measurements since the sensor has to cool down after step 130 before being able to do a temperature measurement. Alternatively, the eggshell temperature measurement can be done with a separate sensor and / or with a different method. In step 150, information about contact between said sensor and said egg is derived from the temperature-induced change in resistance, as will be explained with respect to Figure 5. In step 160, said measured eggshell temperature of step 120 is evaluated based on said derived contact information of step 150. In particular, if the contact information points to a relatively good contact between the sensor and the egg, the measured temperature may be evaluated as being a relatively reliable eggshell temperature, whereas, if the contact information points to a relatively bad contact or a loss of contact, the measured temperature may be evaluated as being a relatively unreliable eggshell temperature. Optionally, a hatching stage of the egg may be determined in step 170 based on said derived contact information and on the evaluated egg-shell temperature, optionally further based on a measured ambient temperature. In further steps, environmental parameters, such as ambient air temperature, humidity, CO2 level or other parameters, of a hatching environment can be adjusted based on the determined hatching stage. Since the present method can allow the hatching stage to be determined, control of the ambient air temperature or other environmental parameters can be improved in that the aim is not to keep an eggshell temperature constant but to tune said parameters to the needs of the egg and / or chick at a determined stage of hatch.

[0033] Figure 5 shows a graph illustrating how contact information between the sensor and the egg is derived (steps 140 - 150) according to the method of Figure 4. The sensor may be configured to utilize a measurement which is used in transient plane source (TPS) methods for determining thermal properties of a material. The use of a single-sided operation mode of the TPS method may be referred to as the modified transient plane source (MTPS) method. In a TPS measurement, a constant current pulse is applied to an electrically conductive layer, while a voltage over the structure ismeasured. As mentioned above, Joule heating will cause the temperature of the electrically conductive layer to increase. The temperature-induced change in electrical resistance is recorded in the voltage measurement. The electrically conductive layer may thus function as both a heater and a temperature sensor. A shape of a temperature response curve based on applying a constant current pulse to the electrically conductive structure or layer depends on the ability of the sensor to exchange heat with its surrounding. Thus, the shape of the temperature response curve depends on thermal effusivity (e) of the object or fluid which the sensor makes contact with. The thermal effusivity of a material is dependent on the thermal conductivity of the material, the density of the material, and the specific heat capacity of the material, which are known for eggshells. Contrary to the known use of TPS measurements, the sensor of the present invention is used with an egg, where good thermal contact cannot be guaranteed during measurements. Further, the egg is not necessarily at equilibrium temperature with the surrounding environment. If the current pulse applied to the electrically conductive layer, indicated as a dotted line 20 in Figure 5, is sufficiently short, for example having a duration of more or less two seconds, heat exchange will not extend beyond a boundary of the egg and the sensed temperature- induced change in resistance may be regarded as a measurement in relation to the egg (with high thermal effusivity) and the surrounding air, (with low thermal effusivity). However, it should be realized that the current pulse need not necessarily be short to avoid probing beyond the boundary of the egg. Instead, the temperature response curve may only be considered during an initial period of time in order for measurements not to be influenced by the heat exchange occurring beyond the egg. The temperature response curve 30 can be plotted by doing for example two measurements, one around a middle of the current pulse and one towards or just before an end of the current pulse. As illustrated in Figure 5, when the temperature response curve is plotted against square root of time 50, the linear parts of the curve are dependent on a percentage of the sensor area making contact with the egg. Thus, two extreme cases of the sensor being fully in contact with the egg and no contact being present at all may define a minimum and maximum slope of the temperature response curve. A slope 40 of the temperature response curve is thus dependent on a percentage of the electrically conductive layer of the sensor being in contact with the egg. A higher slope indicates a higher increase in temperature during the current pulse, caused by a lower capacity to diffuse heat, potentially stemming from an impaired or lost contact between thesensor and the egg. A lower slope indicates a lower increase in temperature during the current pulse, caused by a relatively good diffusion of heat, thanks to a relatively good contact between the sensor and the egg. In this way, contact information of the sensor with the egg can be derived from the sensed temperature - induced change in resistance.

[0034] It should be realized that the sensor need not necessarily apply a current through the electrically conductive layer and sense a voltage across the electrically conductive layer. Alternatively, the sensor may be configured to apply a voltage across the electrically conductive layer and sense a current through said electrically conductive layer. The detected current may be dependent on a resistance of the electrically conductive layer.

[0035] Figure 6 shows a graph representing a potential application of step 170 of the method of Figure 4. Eggs can be transferred to a hatching environment, such as a hatching machine or an on-farm hatching space, in a window ranging from more or less day 15 or 16 to day 18.5, preferably around day 18, of a poultry hatching process when the embryo goes into a rest phase. Said rest phase can be detected by a decrease in eggshell temperature, which may for example be detected through eggshell temperature monitoring in a setter. After transfer to a hatching environment, one or more of the sensor assemblies shown in Figures 1 - 3 can be provided and one or more sensors can be brought into contact with one or more respective eggs according to the method shown in Figure 4. Said sensors can then measure an eggshell temperature over time, which is graphically represented in the upper graph of Figure 6. At the same time contact information between the sensor and the egg can be derived from the lower graph representing a slope of the temperature response curve over time, as shown in, and explained with respect to, Figure 5. This contact information is then further used to evaluate the measured eggshell temperature, in particular a reliability of said eggshell temperature measurement. After a period of a substantially stable eggshell temperature 200 and slope 300 during days 18 and 19, some variations in eggshell temperature 210 show up in combination with some jumps 310 in slope, thus in contact between the sensor and the egg, as shown in the graphs between day 19.1 and 19.6. This may for example be an indication of a start of internal pipping or may be explained by another phase or event in the hatching process. Then,from day 19.6, eggshell temperature measurements start to rise 220 while a slope 320 starts becoming erratic, which may point to the start of the external pipping and hatching. Finally, eggshell temperature measurements 230 in combination with an erratic behaviour of the measured slope 330 both become erratic around day 20, which points to a loss of contact of the sensor with the egg, probably due to a hatching of the chick out of the egg. Since the present method can allow to determine a hatching stage of the egg, hatching parameters, such as air humidity, air temperature, CO2 level or others, can be controlled based on the needs of the eggs / chicks in a predetermined hatching stage, rather than in function of maintaining an eggshell temperature substantially constant.

[0036] Figure 7 shows a suitable computing system 500 comprising circuitry enabling the performance of steps of embodiments of the method for mapping spatial attention according to an aspect of the invention. The computing system 500 may at least partly be integrated in the head mounted device 2, as previously described. Computing system 500 may in general be formed as a suitable general-purpose computer and comprise a bus 510, a processor 502, a local memory 504, one or more optional input interfaces 514, one or more optional output interfaces 516, a communication interface 512, a storage element interface 506, and one or more storage elements 508. Bus 510 may comprise one or more conductors that permit communication among the components of the computing system 500. Processor 502 may include any type of conventional processor or microprocessor that interprets and executes programming instructions. Local memory 504 may include a random-access memory (RAM) or another type of dynamic storage device that stores information and instructions for execution by processor 502 and / or a read only memory (ROM) or another type of static storage device that stores static information and instructions for use by processor 502. Input interface 514 may comprise one or more conventional mechanisms that permit an operator or user to input information to the computing device 500, such as a keyboard 520, a mouse 530, a pen, voice recognition and / or biometric mechanisms, a camera, etc. Output interface 516 may comprise one or more conventional mechanisms that output information to the operator or user, such as a display 540, etc. Communication interface 512 may comprise any transceiver-like mechanism such as for example one or more Ethernet interfaces that enables computing system 500 to communicate with other devices and / or systems, for example with other computingdevices 581 , 582, 583. The communication interface 512 of computing system 500 may be connected to such another computing system by means of a local area network (LAN) or a wide area network (WAN) such as for example the internet. Storage element interface 506 may comprise a storage interface such as for example a Serial Advanced Technology Attachment (SATA) interface or a Small Computer System Interface (SCSI) for connecting bus 510 to one or more storage elements 508, such as one or more local disks, for example SATA disk drives, and control the reading and writing of data to and / or from these storage elements 508. Although the storage element(s) 508 above is / are described as a local disk, in general any other suitable computer-readable media such as a removable magnetic disk, optical storage media such as a CD or DVD, -ROM disk, solid state drives, flash memory cards, ... could be used.

[0037] As used in this application, the term "circuitry" may refer to one or more or all of the following:(a) hardware-only circuit implementations such as implementations in only analog and / or digital circuitry and(b) combinations of hardware circuits and software, such as (as applicable):(i) a combination of analog and / or digital hardware circuit(s) with software / firmware and(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and(c) hardware circuit(s) and / or processor(s), such as microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g. firmware) for operation, but the software may not be present when it is not needed for operation.This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

[0038] Although the present invention has been illustrated by reference to specific embodiments, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied with various changes and modifications without departing from the scope thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. In other words, it is contemplated to cover any and all modifications, variations or equivalents that fall within the scope of the basic underlying principles and whose essential attributes are claimed in this patent application. It will furthermore be understood by the reader of this patent application that the words "comprising" or "comprise" do not exclude other elements or steps, that the words "a" or "an" do not exclude a plurality, and that a single assembly, such as a computer system, a processor, or another integrated unit may fulfil the functions of several means recited in the claims. Any reference signs in the claims shall not be construed as limiting the respective claims concerned. The terms "first", "second", third", "a", "b", "c", and the like, when used in the description or in the claims are introduced to distinguish between similar elements or steps and are not necessarily describing a sequential or chronological order. Similarly, the terms "top", "bottom", "over", "under", and the like are introduced for descriptive purposes and not necessarily to denote relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and embodiments of the invention are capable of operating according to the present invention in other sequences, or in orientations different from the one(s) described or illustrated above.

Claims

CLAIMS1 . A method comprising the steps of- providing a sensor including an electrically conductive layer, the sensor being in direct contact with an egg, the sensor being configured to non-invasively measure a temperature of an eggshell of said egg;- the sensor measuring said eggshell temperature;- generating a current pulse in said sensor, in particular in said electrically conductive layer;- the sensor sensing a temperature - induced change in resistance;- deriving contact information between said sensor and said egg from the sensed temperature - induced change in resistance;- evaluating said measured eggshell temperature based on said derived contact information.

2. The method according to claim 1 , wherein the step of measuring said eggshell temperature includes generating a further current pulse in said sensor, said further current pulse being below a self-heating current threshold for causing heating.

3. The method according to any of the preceding claims, further comprising the step of adjusting environmental parameters of a hatching environment based on the evaluated eggshell temperature.

4. The method according to any of the preceding claims, further comprising the step of determining a hatching stage of said egg based on said derived contact information and on the evaluated egg-shell temperature.

5. The method according to claim 4, further comprising the step of determining an ambient air temperature, wherein the step of determining a hatching stage of said egg is additionally based on said determined ambient temperature.

6. The method according to any of the preceding claims 4 - 5, further comprising the step of adjusting environmental parameters of a hatching environment based on the determined hatching stage.

7. A sensor assembly including- a sensor configured to measure an eggshell temperature, wherein the sensor includes an electrically conductive layer;- a current pulse generator configured to generate a current pulse in said sensor, in particular in said electrically conductive layer;- at least one egg receiving portion configured to receive an egg; wherein the sensor is further configured to sense a temperature - induced change in resistance, wherein the electrically conductive layer of the sensor is included in the at least one egg receiving portion such that an egg lying on said egg receiving portion is at least partially in direct contact with the sensor.

8. The sensor assembly according to claim 7, wherein said at least one egg receiving portion is at least partially concave.

9. The sensor assembly according to any of the preceding claims 7 - 8, the assembly further including a mat including a plurality of said egg receiving portions, the mat being configured to be laid in a hatcher basket.

10. The sensor assembly according to any of the preceding claims 7 - 9, wherein the sensor assembly further includes a protective layer configured to protect the electrically conductive layer and wherein the protective layer is configured to be in direct contact with an egg lying on said egg receiving portion.11 . A hatcher basket comprising a basket bottom and at least one upstanding side wall surrounding said basket bottom, wherein a sensor assembly according to any of the preceding claims 7 - 10 is integrated into said basket bottom.

12. A computer-implemented method comprising the steps of- receiving a measured eggshell temperature from a sensor including an electrically conductive layer, the sensor being in direct contact with an egg;- controlling a current pulse generator to generate a current pulse in said sensor, in particular in said electrically conductive layer;- receiving a sensed temperature-induced change in resistance from said sensor;- deriving contact information between said sensor and said egg based on the sensed temperature - induced change in resistance;- evaluating said measured eggshell temperature based on said derived contact information.

13. A controller comprising at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the controller to perform the method according to claim 12.

14. A computer program product comprising computer-executable instructions for performing the method according to claim 12 when the program is run on a computer.

15. A computer readable storage medium comprising computer-executable instructions for performing the method according to claim 12 when the program is run on a computer.

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