Floor type detection

Abstract

A cleaner head for a floor cleaner comprises a housing, first and second cleaning rollers 30 mounted for rotation within a housing and a floor type sensor 50. The first and second rollers are parallel

Description

B ACKGROUND Floor cleaners with motor driven rotating sweeping and / or mopping rollers are becoming increasingly popular. It has been found that the cleaning performance and energy efficiency of such floor cleaners can be improved by optimising the operating parameters of the floor cleaner depending on the type of floor surface to be cleaned. Some floor cleaners have sensors for identifying floor type. It is against this background that the present invention has been developed. SUMMARY The present invention provides a cleaner head for a floor cleaner, wherein the cleaner head comprises: a housing; first and second cleaning rollers mounted for rotation within the housing; and a floor type sensor, wherein the first and second rollers are parallel to one another, and the floor type sensor is located between the first and second rollers. The present invention is advantageous as the location of the floor type sensor between the rollers helps to protect the sensor from dirt which may damage or obscure the sensor. Optionally the floor type sensor comprises: one or more light detectors configured to output one or more signals indicative of the intensity of one or more visible and / or non-visible wavelengths of light; and one or more processors collectively configured to: receive the one or more signals; and determine a floor type in dependence on the one or more signals. Light detectors provide an economical floor type sensing solution. By locating a light base sensor between the rollers, the sensor is shielded from ambient light which may degrade the accuracy of floor type sensing. The floor type sensor may optionally comprise a light emitter. The cleaner head may be configured so that, in use, the distance between the floor type sensor and a floor surface to be cleaned is in the range 3mm to 100mm. Alternatively, the cleaner head may be configured so that, in use, the distance between the floor type sensor and a floor surface to be cleaned is in the range 5mm to 30mm. alternatively again, the cleaner head may be configured so that, in use, the distance between the floor type sensor and a floor surface to be cleaned is in the range 10mm to 20mm. Optionally the floor type sensor may be located proximate a first side of the housing. This allows for ease of installation and maintenance. The cleaner head may optionally comprise a debris tray located between the first and second rollers, wherein the debris tray extends from a second side of the housing towards the first side of the housing. The debris tray may thereby be installed and removed for cleaning by the user without interference with the sensor. In one example a lowermost surface of the debris tray is configured to be located directly above a floor surface to be cleaned in use, wherein a surface of the floor type sensor is coplanar with the lowermost surface of the debris tray. This positions the sensor close to the floor surface to be cleaned with reduced risk of collision with the floor or an item on the floor. Optionally the cleaner head may comprise first and second floor scrapers, wherein the floor type sensor is located between the first and second floor scrapers. The first floor scraper may be located parallel to and inboard of the first roller, and the second floor scraper may be located parallel to and inboard of the second roller. The floor scrapers may be angled towards their respective roller. In another aspect the present invention provides a cleaner head for a wet floor cleaner comprising the cleaner head described above. The cleaner head may comprise a hydration system for hydrating the first and second rollers and / or the floor surface to be cleaned. In a further aspect the present invention provides a floor cleaner comprising the cleaner head described above. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a perspective view of a vacuum floor cleaner; Figure 2 shows a perspective view of a wet floor cleaner; Figure 3 shows a schematic plan view of the underside of the cleaner head of the floor cleaner of Figure 2; Figures 4a and 4b show schematic side views of the cleaner head of Figure 3; Figure 5 shows a schematic view of a floor type detection system; Figure 6a shows a schematic graphical representation of reflected light intensity variation with wavelength for different ceramic floors in the visible and near infrared spectral range; Figure 6b shows a schematic graphical representation of reflected light intensity variation with wavelength for different vinyl floors in the visible and near infrared spectral range; Figure 6c shows a schematic graphical representation of reflected light intensity variation with wavelength for different wood floors in the visible and near infrared spectral range; Figure 6d shows a schematic graphical representation of reflected light intensity variation with wavelength for a laminate floor in the visible and near infrared spectral range; Figure 7 shows a schematic view of a light sensor; Figures 8a to 8d show the schematic graphical representations of reflected light intensity variation with floor type and wavelength as shown in Figures 6a to 6d; Figure 9 shows a schematic view of another floor type detection system; Figures 10a to lOd show schematic graphical representations of reflected light intensity variation with wavelength for four different materials; Figures Ila to 11c show schematic representations of reflected light intensity variation with wavelength for surface water; Figure 12 shows test data comparisons for several different floor type sensor configurations. Figure 13 shows a schematic representation of a control system; and Figure 14 shows a flowchart describing a process of controlling a floor cleaner. DETAILED DESCRIPTION Figure 1 shows a vacuum floor cleaner 10 according to an embodiment of the disclosure comprising a main body 12, a wand 14 and a cleaner head 16. The main body 12 comprises a separating system 13 in the form of a cyclonic separator, a motor and impeller (not visible) arranged to draw air through the separating system 13, and a power supply, in the form of a battery 11, for powering the motor. The wand 14 is attached at one end to the main body 12 and at the other end to the cleaner head 16. The wand 14 provides fluid communication between the cleaner head 16 and the separating system 13 within the main body 12 and supports the cleaner head 16 during use. The cleaner head comprises a brush bar roller 17 for sweeping the floor surface to be cleaned during use. The brush bar roller 17 is configured to rotate in use to agitate dust and debris on the floor surface to be cleaned so that it can be drawn into the separation system 13 for separation and disposal. In this example, the cleaner head 16 comprises one brush bar roller 17 located within a housing 18 of the cleaner head 16. However, in another example, the cleaner head 16 may comprise two or more brush bar rollers arranged one in front of the other and / or side by side. A floor type sensor 50 (as will be described in greater detail below) is located in the housing 18. Figure 2 shows a wet floor cleaner 20 according to an embodiment of the disclosure comprising a main body 22, a handle 24 and a cleaner head 26. The main body 22 comprises a water distribution system having a clean water tank 21, a waste water tank 23 and corresponding clean and waste water pumps (not shown). The water distribution system is arranged to deliver clean water to a floor surface to be cleaned and / or to one or more mopping rollers 30, and to remove soiled water from a debris collection tray 32 (Figure 3) and / or from mopping rollers 30. The handle 24 is attached at one end to the main body 22. An electronic user interface 25 in the form of a touch screen is located at an upper end of the handle 24. The cleaner head 26 of the wet floor cleaner 20 comprises a pair of mopping rollers 30 for cleaning the floor surface during use. Figure 3 shows a schematic plan view of the underside of the cleaner head 26 of the wet floor cleaner 20, and Figures 4a and 4b show schematic side views of the cleaner head 26. The cleaner head 26 comprises a housing 28 within which are located two mopping rollers 30. The mopping rollers 30 are supported for rotation within the housing 28 and spaced apart such that each roller 30 is located proximate the front 31 and rear 32 of the housing 28 (where the front 31 of the housing 28 corresponds to a leading side of the housing 28 when a user pushes the wet floor cleaner 20 forward in use, and where the rear 32 of the housing 28 corresponds to a leading side of the housing 28 when a user pulls the wet floor cleaner 20 back in use). As best shown in Figures 4a and 4b, resilient scrapers 36 are located proximate each mopping roller 30. The scrapers 36 are located inboard of the mopping rollers 30 and are configured to scrape debris and water from the floor surface 29 during cleaning. A removeable debris tray 33 for collecting water and debris is located between the mopping rollers 30. The debris tray 33 extends from a second side 35 of the housing 28 towards a first side 34 of the housing 28. A floor type sensor 50 (as will be described in greater detail below) is located proximate the first side 35 of the housing 28 between the rollers 30 and the scrapers 36. It will be understood that the scrapers 36 are not essential and may be omitted. In this example, a lower surface 37 of the floor type sensor 50 is co-planar with the lowermost surface 38 of the debris tray 33 which is arranged to be located directly above the floor surface 29 during use. In this example, the distance 39 (see Figure 4b) between the lowermost surface 38 of the debris tray 33 (and therefore also the lowermost surface 37 of the floor type sensor 50) and the floor surface 29 in use is 15mm. However, the distance 39 between the lowermost surface 38 of the sensor 50 and the floor surface 29 in use may be any suitable size in the range 3mm to 100mm, alternatively in the range 5mm to 30mm, or alternatively again in the range 10mm to 20mm. In use, the distance between the lower surface of the sensor 50 and the floor surface 29 is 15mm in this example. A distance between the lower surface of the sensor 50 and the floor surface 29 of between around 10mm and 20mm has been found to provide improved performance. Reducing the distance to less than 10mm may result in a drop in performance due to decreased field of view of the sensor 50, which may result in a smaller area of the floor being sampled and less accurate results. Increasing the distance to above 20mm may be possible, for example up to around 100mm or even up to around 350mm, but this may require additional optical features to prevent a drop in performance. Preferably the distance between the lower surface of the sensor 50 and the floor surface 29 is less than around 150mm. Figure 5 shows a schematic representation of a floor type detection system 70 comprising a floor type sensor 50. In this example, the floor type sensor 50 comprises a pair of light emitters 52, a first light detector 54 and a second light detector 56. In this example, the light emitters 52 comprise light emitting diodes (LED) configured to emit light 55 having wavelengths spanning the visible and infrared spectrums from 440nm to 950mn. However, any suitable LED or other light source capable of emitting light spanning the visible and infrared light spectrums may be used. In use, a portion of the light 55 emitted by the light emitters 52 is reflected from the floor surface 29 to be cleaned. The first light detector 54 is configured to detect reflected visible light 57 of a specific wavelength in the visible light spectrum, and the second light detector 56 is configured to detect reflected light 58 of a specific wavelength in the near infrared (NIR) spectrum. In this example, the first light detector 54 is configured to detect visible light 57 having a wavelength of 555nm, and the second light detector 56 is configured to detect NIR light 58 having a wavelength of 910nm. It will be understood that the above examples are illustrative only, and that the first light detector 54 may be configured to detect visible light 57 of a specific wavelength in the range 400 to 750nm, and the second light detector 56 may be configured to detect light 58 of a specific wavelength in the range 751 to 1 lOOnm. The first and second light detectors 54, 56 are configured to output first and second signals 64, 66 respectively, where the first signal 64 is indicative of the intensity of the reflected visible light 57, and the second signal 66 is indicative of the intensity of the reflected NIR light 58. The first and second signals are received by a processor 110 of a control system 100. The processor 110 is configured to determine a floor type or floor identifier in dependence on the first and second signals 64, 66, and to determine one or more operating parameters of the wet floor cleaner 20 and to output at least one control signal 102 comprising one or more instructions to operate the wet floor cleaner 20 in accordance with the one or more operating parameters as will be described in greater detail below. Figures 6a to 6d show schematic graphical representations of characteristic reflected light intensity variation with wavelength for different ceramic, vinyl, wood and laminate floors respectively in the visible and near infrared spectral range. As shown in Figures 6a to 6d, the intensity of the reflected light varies across the spectrum and varies depending on floor material type, colour and surface finish. The variation of the reflected light intensity across the spectrum is a characteristic of the floor which may be used to identify the floor type or a floor identifier associated with a particular floor such as colour or surface finish. Referring to Figure 6a, traces 150a, 150b show the characteristic reflected light variation traces for two different ceramic floors, referring to Figure 6b, traces 160a, 160b show the characteristic reflected light variation traces for two different vinyl floors, referring to Figure 6c, traces 170a, 170b show the characteristic reflected light variation traces for two different wooden floors, and referring to Figure 6d, trace 180a shows the characteristic reflected light variation traces for a laminate floor. The floor type sensor 50 described above is able to detect light in the visible spectrum having a wavelength of 555nm - indicated by line A in Figures 6a and 6b, and to detect light in the NIR spectrum having a wavelength of 910nm - indicated by line B in Figures 6a and 6b. If the first detector 54 detects reflected visible light 57 of intensity xl, and the second detector detects reflected NIR light 58 of intensity yl, this corresponds to the ceramic floor having the characteristic trace 150b. Alternatively, if the first detector 54 detects reflected visible light 57 of intensity x2, and the second detector detects reflected NIR light 58 of intensity y2, this corresponds to the vinyl floor having the characteristic trace 160a. Consequently, the reflected light intensity signals 64, 66 received by the processor 110 from the detectors 54, 56 can be used by the processor 110 to identify the floor type, or a floor identifier such as colour, by comparing the reflected light intensities with known reference characteristic reflected light intensity traces for different types / colours of floor. Alternatively, the floor type or floor identifier may be identified by implementing machine learning algorithms which are able to identify a floor type or floor identifier in dependence on the reflected light intensity signals 64, 66. Figure 7 shows a schematic view of an alternative floor type sensor 250 that may be used in the floor type detection system 70. In this example, the floor type sensor 250 comprises a light emitter 252, an array 253 of first light detectors 254, and a second light detector 256. In this example, the light emitter 252 comprises a LED configured to emit light having wavelengths spanning the visible and infrared spectrums from 400nm to HOOmn. However, any suitable LED or other light source capable of emitting light spanning the visible and infrared light spectrums may be used. As above, in use, a portion of the light emitted by the light emitter 252 is reflected from the floor surface to be cleaned. The array 253 of first light detectors 254 is configured to detect reflected visible light of a plurality of different specific wavelengths in the visible light spectrum, and the second light detector 256 is configured to detect reflected light of a specific wavelength in the NIR spectrum. In this example, the floor type sensor 250 comprises an array 253 of sixteen first light detectors 254 configured to detect visible light having wavelengths of 415nm, 445nm, 480nm, 515nm, 555nm, 590nm, 630nm, 680nm, and a second light detector 256 is configured to detect NIR light having a wavelength of 910nm. Each of the first light detectors 254 in the array 253 is configured to detect light of a specific wavelength, with two first light detectors 254 being provided per specific wavelength. However, this is not essential, and in a different example, only one first light detector 254 in the array is provided per specific wavelength. In another example, more than two first light detectors 254 may be provided in the array 253 per specific wavelength. Each light detector 254 in the array 253 is configured to output a signal 264 indicative of the intensity of light at one of the plurality of visible wavelengths, and the second light detector 256 is configured to output a second signal 266 indicative of the intensity of the reflected NIR light. It will be understood that for clarity only one of the signals 264 is illustrated in Figure 7. It will be understood that the above examples are illustrative only, and that the first light detectors 254 in the array 253 may be configured to detect visible light of any suitable number of specific wavelengths in the range 400 to 750nm, and the second light detector 256 may be configured to detect light of a specific wavelength in the range 751 to 1 lOOnm. In another example, more than one second light detector 256 may be provided, each configured to detect a specific wavelength in the range 751nm to 1 lOOnm, and each configured to output a signal 266 indicative of the intensity of the specific wavelength of reflected light in the range 751nm to 1 lOOnm. The plurality of signals 264, and the second signal 266, are received by the processor 110 (Figure 5) of the control system 100. The processor 110 is configured to determine a floor type or floor identifier in dependence on the plurality of signals 264, and the second signal 266, and to determine one or more operating parameters of the wet floor cleaner 20 and to output at least one control signal 102 comprising one or more instruction to operate the wet floor cleaner 20 in accordance with the one or more operating parameters as will be described in greater detail below. Figures 8a to 8d show the same schematic graphical representation of characteristic reflected light intensity variation with floor type and wavelength as in Figures 6a to 6d. The floor type sensor 250 described above is able to detect light in the visible spectrum having wavelengths of 415nm, 445nm, 480nm, 515nm, 555nm, 590nm, 630nm, 680nm -indicated by lines Al to A8, and to detect light in the NIR spectrum having a wavelength of 910nm - indicated by line B. Consequently, there are additional data points available in the visible light portion of the spectrum than for sensor 50 described above allowing increased accuracy of floor type or floor characteristic identification. The data points to identify the vinyl floor corresponding to characteristic trace 160a are shown on Figure 8b for illustrative purposes. The reflected light intensity signals 264, 266 received by the processor 110 can be used by the processor to identify the floor type or floor identifier by comparing the reflected light intensity data points with reference characteristic reflected light traces for different types of floor. Alternatively, the floor type or floor identifier may be identified by implementing machine learning algorithms which are able to identify floor type or floor identifier in dependence on the reflected light intensity signals 264, 266. It will be understood that although Figures 6a to 6d, and Figures 8a to 8d, show scaled reflected light intensity traces, this is illustrative only and absolute or normalised (or otherwise pre-processed) reflected light intensity data may equally well be used. The reflected light intensity data need not be a continuous trace and may rather be an array of data points. Figure 9 shows a schematic representation of another floor type detection system 370 comprising a floor type sensor 350. In this example, the floor type sensor 350 comprises a pair of light emitters 352 and light detectors 354a, 354b, 354c, 354d. In this example, the light emitters 352 comprise incandescent light bulbs. However, any suitable light source capable of emitting a spectrum of short wave infrared light (SWIR) may be used, where SWIR light includes light having wavelengths in the range 1100 to 2500nm. In some embodiments, only a single light emitter 352 is provided. In use, a portion of the light 355 emitted by the light emitters 352 is reflected from the floor surface 29 to be cleaned. Each light detector 354a, 354b, 354c, 354d is configured to detect reflected SWIR light 357 of a specific wavelength. In this example, the light detector 354a is configured to detect SWIR light 357 having a wavelength of 1450nm, the light detector 354b is configured to detect SWIR light 357 having a wavelength of 1700nm, the light detector 354c is configured to detect SWIR light 357 having a wavelength of 1920nm, and the light detector 354d is configured to detect SWIR light 357 having a wavelength of 2150nm. It will be understood that the above examples are illustrative only, and that the light detectors 354a, 354b, 354c, 354d may be configured to detect SWIR light 357 of specific wavelengths in the range 1100 to 2500nm. The light detectors 354a, 354b, 354c, 354d are each configured to output signals 364a, 364b, 364c, 364d respectively, where the signal 364a is indicative of the intensity of the reflected SWIR light 357 at 1450nm, the signal 364b is indicative of the intensity of the reflected SWIR light 357 at 1700nm, the signal 364c is indicative of the intensity of the reflected SWIR light 357 at 1920nm, and the signal 364d is indicative of the intensity of the reflected SWIR light 357 at 2150nm. The signals 364a, 364b, 364c, 364d are received by the processor 110 of the control system 100. The processor 110 is configured to determine a floor type or floor identifier in dependence on the signals 364a, 364b, 364c, 364d, and to determine one or more operating parameters of the wet floor cleaner 20 and to output at least one control signal 102 comprising one or more instructions to operate the wet floor cleaner 20 in accordance with one or more operating parameters as will be described in greater detail below. Figures 10a to lOd show schematic graphical representations of characteristic reflected SWIR light intensity variation with wavelength for four different materials. As shown in Figures 10a to lOd, the intensity of the reflected SWIR light varies across the spectrum and varies depending on floor material type. Trace 450a in Figure 10a shows the characteristic normalised reflected SWIR light variation for a wood floor, trace 450b in Figure 10b shows the characteristic normalised reflected light variation for a ceramic floor, trace 450c in Figure 10c shows the characteristic normalised reflected light variation for a vinyl floor, and trace 450d in Figure 10c shows the characteristic normalised reflected light variation for a laminate floor. The floor type sensor 350 is able to detect reflected SWIR light having wavelengths of 1450nm, 1700nm, 1920nm, and 2150nm - indicated by data points in Figures 10a to lOd respectively. As shown in Figures 10a to lOd, the characteristic traces 450a, 450b, 450c, 450d are distinct for each material type. Consequently, the reflected SWIR light intensity signals 364a, 364b, 364c, 364d received by the processor 110 from the detectors 354a, 354b, 354c, 354d can be used by the processor to identify the floor type or floor identifier by comparing the normalised reflected SWIR light intensity data points with known reference characteristic reflected SWIR light traces for different floor materials. Alternatively, the floor type or floor identifier may be identified by implementing machine learning algorithms which are able to identify floor type or floor identifier in dependence on the reflected SWIR light intensity signals 364a, 364b, 364c, 364d. Although normalised reflected SWIR light intensities are shown in Figures 10a to lOd and described above, it will be understood that this is illustrative only and that absolute, scaled (or otherwise pre-processed) reflected light intensity data may equally well be used. It will be understood that the use of four detectors 354a, 354b, 354c, 354d in the example above is illustrative only, and that in other examples fewer light detectors, or a greater number of light detectors may be used. In addition, it will be understood that the specific SWIR wavelengths described above are illustrative only and that any suitable number of wavelengths in the range HOOnm to 2500nm may be used. To improve accuracy of floor type or floor identifier identification, it may be beneficial to use at least three reference wavelengths above 1400nm.The sensor 350 described above with respect to Figure 9 differs from the sensors 50, 250 described above with respect to Figures 5 and 7 respectively in that the light detectors 354a, 354b, 354c, 354d of the sensor 350 are configured to detect reflected SWIR light, whereas the detectors 54, 56, 254, 256 of the sensors 50, 250 are configured to detect visible and NIR reflected light. SWIR light 355 that is incident on a floor surface 29 is able to penetrate into the material of the floor to a degree where it reveals the molecular structure of the floor material. By contrast, visible and NIR light 55 that is incident on a floor surface 29 is reflected by the surface or surface coating of the floor. As a consequence of this, the characteristic traces 450a, 450b, 450c, 450d corresponding to the different materials are predictable and repeatable as they are dependent on the material properties of the floor and not on its colour or finish. Certain wavelengths of SWIR light are absorbed by certain floor materials. Such absorption wavelengths can be used to identify the floor material by targeting known absorption frequencies for particular materials. For example, laminate absorbs light having wavelengths of 1450nm and 1850nm, vinyl absorbs light having a wavelength of 1650nm, and wood absorbs light having a wavelength of 1950nm. By incorporating light detectors configured to detect SWIR light of these particular wavelengths, the sensor 350 may be able to more effectively detect particular materials by the presence of absorption bands in the characteristic reflected light traces associated with these particular wavelengths. The sensor 350 may comprise light detectors for all such wavelengths, or alternatively may comprise light detectors for multiple wavelengths, some of which are associated with detection of one or more particular materials, and some of which are not associated with detection of a particular material. Figures 1 la to 11c show schematic representations of characteristic reflected light intensity variation with wavelength for surface water. Figure Ila represents a characteristic light pattern for a drop of water detected by a visible light sensor, Figure 11b represents a characteristic light pattern for a drop of water detected by a SWIR light sensor able to detect light having a wavelength of 1450nm, and Figure 11c represents a characteristic light pattern for a drop of water detected by a SWIR light sensor able to detect light having a wavelength of 1920nm. By using SWIR light detectors able to detect light having a wavelength of 1450nm and / or 1920nm, it is possible to detect the presence of surface water. Conversely, the inventors have found that due to the absorption of these wavelengths by water molecules, it may not be possible to infer further information (e.g. floor type) about a wet / damp floor based on detecting these wavelengths alone. In such cases it may be useful to also detect wavelengths from other parts of the visible, NIR or SWIR spectrum. For example, since water is transparent to visible light, the reflected light detected in the visible spectrum would be largely unchanged for a wet / damp floor compared to a dry floor. As will be described in greater detail below, this information may be used by the controller 100 to issue a control signal 102 comprising an instruction to increase the rotational speed of the mopping rollers 30 of the wet floor cleaner 20 until the surface water has been removed. It will be understood that it is not essential to use SWIR light detectors able to detect light having a wavelength of 1450nm and / or 1920nm to detect surface water, and that SWIR light detectors able to detect light having a wavelength in the range 1440nm to 1460nm and / or 1900nm to 2000nm may be used. As mentioned above, it may be useful to detect wavelengths from parts of the visible (400nm to 750nm), NIR (751nm to 1 lOOnm) or SWIR (1 lOOnm to 2500nm) spectrum. The sensors 50, 250 described above detect wavelengths from parts of the visible and NIR spectrums, and the sensor 350 described above detect wavelengths from parts of the SWIR spectrum. A sensor comprising light detectors able to detect wavelengths from parts of at least two of the visible, NIR and / or SWIR spectrums is also contemplated. Figure 12 is a bar chart showing test results comparing floor detection accuracy for different configurations of floor type sensor. The first bar 380 shows that in a test of a floor type sensor having a plurality of light detectors configured to detect reflected light in the visible spectrum, and one light detector configured to detect reflected light in the NIR spectrum (i.e. the floor type sensor 250 described above), the average accuracy of floor detection is 54%. The second bar 381 shows an average accuracy of 70% for a floor type detector comprising only two light detectors in the SWIR spectrum. The third bar 382 shows an average accuracy of 72% for a floor type detector comprising a combination of the floor type sensor 250 and two light detectors in the SWIR spectrum. These results show that a floor type detector comprising only two light detectors in the SWIR spectrum is more accurate, on average, than the floor type detector 250, but that a floor type detector comprising a combination of the floor type sensor 250 and two light detectors in the SWIR spectrum is more accurate than each individually. The fourth bar 383 shows an average accuracy of 78% for a floor type detector comprising only four light detectors in the SWIR spectrum. The fifth bar 384 shows an average accuracy of 80% for a floor type detector comprising a combination of the floor type sensor 250 and four light detectors in the SWIR spectrum. The sixth bar 385 shows an average accuracy of 81% for a floor type sensor having an array of eight light detectors configured to detect reflected light in the SWIR spectrum. These results show that floor type sensors having more detectors in the SWIR range are more accurate than those with less, and that, even so, a floor type sensor comprising a combination of the floor type sensor 250 and four light detectors in the SWIR spectrum is more accurate than a floor type sensor comprising only four light detectors in the SWIR spectrum. It will be understood that any combination of light detectors as best suits intended end use and floor cleaner type may be selected. Although not explicitly described above, it will be understood that a floor type sensor comprising a plurality of light detectors configured to detect reflected light in the visible spectrum, and one or more light detectors configured to detect reflected light in the SWIR spectrum is contemplated. As mentioned above, the reflected light intensity signals (absolute, scaled or normalised) received by the processor 110 from the detectors can be used by the processor 110 to identify the floor type or floor identifier. In one example, this is achieved by comparing the reflected light intensity data points with known reference characteristic reflected light traces for different types and / or colour of floor. For floor type sensors which use visible and NIR light detectors, such as sensors 50 and 250 described above, the reflected light intensity signals can be compared to reference characteristic trace data stored in a look-up table which contains a plurality of characteristic traces for different types, colours and finishes of floor surface. The floor characteristics in the look-up table may be pre-loaded, or may be obtained from floors in a user’s home using the sensor 50, 250 as described in greater detail below. Where a floor identifier (such as colour) is identified by the processor 110, the floor identifier is used to identify floor type by referencing correlation data (also stored in the look-up table) which links specific floor identifiers to specific floor types. The same method of determining floor type or floor identifier can be used for floor type sensors which use SWIR light detectors, such as sensor 350 described above. In this case, the reflected light intensity data points can be compared to reference characteristic traces stored in a look-up table which contains a plurality of characteristic traces for different floor materials (and optionally also different floor colours and finishes). In either case, the reference characteristic reflected light traces may contain absolute intensity values at each of the wavelengths detected, and / or they may contain relative intensity values for each of the wavelengths detected (e.g. expressed in the form of a fraction or percentage of intensity values for one or more of the other detected wavelengths). The data points obtained by the floor type sensor 50, 250, 350 enable a floor type or floor identifier to be determined by comparison to known reference characteristic traces. The determined floor type or floor identifier may then be used to determine an operating parameter of the wet floor cleaner 20. In another example, the data points obtained by the floor type sensor 50, 250, 350 can be provided as input data to a machine learning algorithm which is configured to use the data points to determine floor type or floor identifier. Example machine learning methods include statistical learning methods such as Linear Discriminant Analysis Once determined, the floor type or floor identifier can then be used to determine an operating parameter of the wet floor cleaner 20 which is dependent on the determined floor type. Figure 13 depicts the control system 100. The controller 100 comprises the processor 110 and a memory device 120. The processor 110 may be one or more electronic processing device which operably executes computer-readable instructions. The memory device 120 may be one or more memory device. The memory device 120 is electrically coupled to the processor 110 and configured to store instructions and / or data (for example a look-up table containing characteristic floor type trace data and / or floor identifier correlation data). The processor 110 is configured to access the memory device 120 to execute the instructions stored thereon, to access data stored thereon and / or to store data thereon. The controller 100 comprises at least one input 140 and at least one output 145. The at least one input 140 may comprise an electrical input of the controller 10. The at least one output 145 may comprise an electrical output of the controller 100. The at least one input 140 is arranged to receive the reflected light intensity signals 64, 66, 264, 266, 364a-d from the sensors 50, 250, 350, and the one or more output 145 is arranged to output one or more control signals 102 comprising one or more instruction to operate the wet floor cleaner 20 in accordance with the one or more operating parameters determined by the processor 110. The operating parameters of the wet floor cleaner 20 include speed of rotation of the mopping rollers 30 and hydration level to be applied to the mopping rollers 30 and / or floor 29. Once the floor type or floor identifier has been determined, the processor 110 determines appropriate operating parameters and outputs one or more control signals 102 comprising one or more instructions to operate the wet floor cleaner 20 in accordance with the determined operating parameters. In the case that the wet floor cleaner 20 comprises a floor type sensor 350 having detectors configured to detect reflected SWIR light having a wavelength in the range 1440nm to 1460nm and / or 1900nm to 2000nm, the processor 110 may be configured to determine if there is surface water on the floor If it is determined that surface water is present, the processor 110 may be configured to determine a speed of rotation for the mopping rollers 30 that is greater than their standard speed of rotation for the floor surface in question and / or may be configured to reduce the hydration level to be applied to the mopping rollers 30 and / or floor 29. In the case of a dry floor cleaner such as vacuum cleaner 10, if it is determined that surface water is present, the processor 110 may be configured to disable the vacuum cleaner. The floor type determined by the processor 110 may be provided as a suggested floor type to a user via a user interface. In an example process 400 (depicted schematically in Figure 14) the control system 100 is configured to receive the detector signals 64, 66, 264, 266, 364a-d from the floor type detection system 70, 270, 370 at step 401, and to determine a detected floor type in dependence on the one or more detector signals at step 402. At step 403 the control system outputs a detected floor type signal which may be received, and displayed to a user, by the user interface 25 at step 404. Upon receipt of the detected floor type information, at step 405, the user can input an instruction to accept or reject the detected floor type. At step 406a, 406b, the acceptance or rejection of the detected floor type is received as an input signal by the control system 100. In the case that the user accepts the detected floor type, at step 407 the control system 100 is configured to determine one or more operating parameters of the floor cleaner in dependence on the detected floor type, and at step 408 output at least one control signal 102 comprising one or more instructions to operate the floor cleaner 20 in accordance with the one or more operating parameters. In the case that the user rejects the detected floor type, the user interface 25 is configured to allow the user to input the floor type at step 409. The user interface 25 then issues a signal indicative of the user identified floor type to the control system 100 at step 410. At step 411 the control system 100 determines one or more operating parameters of the floor cleaner 20 in dependence on the user-identified floor type, and, as above, outputs at least one control signal comprising one or more instructions to operate the floor cleaner in accordance with the one or more operating parameters at step 408. In the case that the user accepts the detected floor type (step 406a), the control system 100 may be configured to associate the detected data points with the detected floor type at step 412, and issue an instruction to store the association between the detected data points and the detected floor type (for example in a look-up table stored in memory device 120) at step 413. Alternatively, in the case that the user rejects the detected floor type (step 406b), the control system may be configured to associate the detected data points with the user-identified floor type at step 414, and, as above, issue an instruction to store the association between the detected data points and the user-identified floor type (for example in a lookup table stored in memory device 120) at step 413. It will be understood that many variations to the above examples are possible. In particular, the light emitters 52, 252, 352 may be separate to the sensors 70, 270, 370. In addition, the user interface 25 need not be an integral part of the floor cleaner but may instead be a remote device such as a mobile telephone, tablet or computer. Although the examples above have in the main been given in the context of a wet floor cleaner 20 having a pair of mopping rollers 30 with a floor type sensor 50, 250, 350 located between them, it will be understood that all of the examples may also be used with only one, or more than two, mopping rollers. The floor type detection system may be used with a dry floor cleaner such as a vacuum cleaner 10 having only one, or a plurality, of agitators. The floor cleaner 10, 20 may be user operated or may be a self-propelled robotic floor cleaner.

Claims

1. A cleaner head for a floor cleaner, wherein the cleaner head comprises: a housing;first and second cleaning rollers mounted for rotation within the housing; anda floor type sensor,wherein the first and second rollers are parallel to one another and the floor type sensor is located between the first and second rollers.

2. The cleaner head of claim 1, wherein the floor type sensor comprises:one or more light detectors configured to output one or more signals indicative of the intensity of one or more visible and / or non-visible wavelengths of light; andone or more processors collectively configured to:receive the one or more signals; anddetermine a floor type in dependence on the one or more signals.

3. The cleaner head of claim 2, wherein the floor type sensor comprises a light emitter.

4. The cleaner head of any preceding claim, configured so that, in use, the distance between the floor type sensor and a floor surface to be cleaned is in the range 3mm to 100mm.

5. The cleaner head of claim 4, configured so that, in use, the distance between the floor type sensor and a floor surface to be cleaned is in the range 5mm to 30mm.

6. The cleaner head of claim 5, configured so that, in use, the distance between the floor type sensor and a floor surface to be cleaned is in the range 10mm to 20mm.

7. The cleaner head of any preceding claim, wherein the floor type sensor is located proximate a first side of the housing.

8. The cleaner head of claim 7, comprising a debris tray located between the first and second rollers, wherein the debris tray extends from a second side of the housing towards the first side of the housing.5 9. The cleaner head of claim 8, wherein a lowermost surface of the debris tray isconfigured to be located directly above a floor surface to be cleaned in use, wherein a surface of the floor type sensor is co-planar with the lowermost surface of the debris tray.

10. The cleaner head of any preceding claim, comprising first and second floor 10 scrapers, wherein the floor type sensor is located between the first and second floorscrapers.

11. A cleaner head for a wet floor cleaner comprising the cleaner head of any preceding claim.1512. A floor cleaner comprising the cleaner head of any preceding claim

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