A lighting management system

Abstract

The invention provides a lighting management system comprising: a plurality of lighting devices; a control system; a user interface device; wherein each lighting device of the plurality of lighting devices comprises a respective driver module configured to determine values of operational parameters of a set of operational parameters, and to convey the determined values to the control system; wherein the control system is configured, for each respective driver module of the plurality of lighting devices, to: (i) select at least two first operational parameters from the set of operational parameters, and (ii) calculate a first composite metric (C1) based on the determined values of the selected at least two first operational parameters; (iii) select at least two second operational parameters from the set of operational parameters, wherein the at least two second operational parameters are different from the at least two first operational parameters, and (iv) calculate a second composite metric (C2) based on the determined values of the selected at least two second operational parameters; wherein the user interface device is configured to: obtain a signal indicative of the first composite metric (C1) and the second composite metric (C2) from the control system; render a visual representation having a first composite metric axis and a second composite metric axis, and for each respective driver module of the plurality of lighting devices plot a point within the visual representation corresponding to the first composite metric and the second composite metric.

Description

[0001] A lighting management system

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a lighting management system. The invention further relates to a corresponding method, and computer program product. The invention further relates to a control system of such a lighting management system. The invention further relates to a user interface. The invention further relates to a lighting device arranged for operating within such a lighting management system.

[0004] BACKGROUND OF THE INVENTION

[0005] LED based lighting devices have revolutionized the global lighting market.

[0006] LED based lighting device are driven by a LED driver, which become increasingly smarter in the current digitally connected world. Such a LED driver may alternatively be known as a LED driver module. For example, modem LED driver modules with a digital interface collect vast amounts of data on various operational parameters. Such operational parameters may for example be the input (mains) voltage, the surge voltage or current events, brownouts, cold-start events, lightning strikes, the driver module temperature, and / or the LED board temperature.

[0007] Consequently, due to the availability of various data, health monitoring and reliability monitoring of a plurality of LED based lighting devices - such as a fleet of streetlights - has become easier and more common. The most simplistic option for representing LED driver health and / or reliability would be to provide a single number for each driver module, for example the calculated remaining useful life of the LED driver module (“your driver module has 2.5 years remaining of useful life before possible failure” .

[0008] However, the applicant has found that a single number is too simplistic to truly capture and communicate the complex health state of a modem LED driver module, while on the other hand a vast array of numbers becomes too complicated for human interpretation, e.g. for a responsible maintenance expert. It is also found that communication of such telemetry data to a backend is not free.

[0009] Hence, there is a clear need for tools that increases the interpretability of driver module-reliability related data while (A) preserving the maximum amount of information (or operational metrics) of the LED driver module, and (B) enabling a dynamic and human- interpretable visualization of said information, and (C) preferably reducing the cost for communication doing so.

[0010] SUMMARY OF THE INVENTION

[0011] It is an object of the invention to provide an improved lighting management system, which at least alleviates the problems and disadvantages mentioned above. Thereto, the invention is defined by the appended claims.

[0012] Thereto, the invention provides a lighting management system comprising: a plurality of lighting devices; a control system; a user interface device; wherein each lighting device of the plurality of lighting devices comprises a respective driver module configured to determine values of operational parameters of a set of operational parameters, and to convey the determined values to the control system; wherein the control system is configured, for each respective driver module of the plurality of lighting devices, to: (i) select at least two first operational parameters from the set of operational parameters, and (ii) calculate a first composite metric (Cl) based on the determined values of the selected at least two first operational parameters; (iii) select at least two second operational parameters from the set of operational parameters, wherein the at least two second operational parameters are different from the at least two first operational parameters, and (iv) calculate a second composite metric (C2) based on the determined values of the selected at least two second operational parameters; wherein the user interface device is configured to: obtain a signal indicative of the first composite metric (Cl) and the second composite metric (C2) from the control system; render a visual representation having a first composite metric axis and a second composite metric axis, and for each respective driver module of the plurality of lighting devices plot a point within the visual representation corresponding to the first composite metric and the second composite metric.

[0013] Hence, the lighting management system according to the present invention enables the control system to obtain determined values of operational parameters of a set of operational parameters, from each respective driver module of the plurality of lighting devices. Said determined values may be telemetry data of the respective driver module of the plurality of lighting devices.

[0014] Hence, each driver module may be configured to obtain telemetry data, and to determine values of operational parameters of said set of operational parameters. Throughout the application, said ‘determining’ may alternatively be phrased as obtaining, measuring, or calculating. For example, each lighting device of the plurality of lighting devices comprises a respective driver module configured to measure values of operational parameters of a set of operational parameters.

[0015] For each respective driver module of the plurality of lighting devices, the control system then selects at least two first operational parameters from the set of operational parameters, and calculates a first composite metric (Cl) based on the determined values of the selected at least two first operational parameters. Similarly, the control system also selects at least two second operational parameters from the set of operational parameters, wherein the at least two second operational parameters are different from the at least two first operational parameters, and (iv) calculate a second composite metric (C2) based on the determined values of the selected at least two second operational parameters. As a result, the control system is configured to calculate (at each moment in time) a first composite metric (Cl) and a second composite metric (C2) based on the obtained determined values of the respective operational parameters from each driver module.

[0016] Hence, the lighting management system according to the present invention advantageously creates a first composite metric (Cl) and a second composite metric (C2) respectively from differently selected at least two operational parameters. This condenses the obtained determined values, hence condenses the information pertaining to the health of each driver module.

[0017] Subsequently, the user interface device according to the present invention advantageously renders a visual representation having a first composite metric axis and a second composite metric axis, and for each respective driver module of the plurality of lighting devices plots a point within the visual representation corresponding to the first composite metric and the second composite metric. This ensures that the determined values, which are condensed in the first (Cl) and second composite metrics (C2) respectively for each driver module (at each moment in time), are visualized in an ergonomic and human- interpretable manner.

[0018] Hence, in embodiments, the visual representation may particularly be a two- dimensional visual representation, such as for example a scatter plot with the X-axis representing the ranges for the first composite metric (Cl) and the Y-axis representing the ranges for the second composite metric (C2).

[0019] Hence, each point entry in the visual representation represents the health status of one specific LED driver module, and altogether the resulting cloud of points represents the health of the plurality of lighting devices on fleet level. Since the points are rendered relative to each other in the same visual representation, the resulting cloud of points provides a context for each specific LED driver module and how its health relates to the fleet (or rest of population). It may for example be easy to detect an outlier in the cloud of points, which may be indicative of the health development of a particular LED driver module not behaving conform the health development of the remaining LED driver modules of the fleet (or rest of population).

[0020] This invention is particularly advantageous for maintenance experts viewing the same visual representation over time, and which can track each point (i.e. representing the health of the driver module) to identify anomalies in de dynamic development of the points plotted within the visual representation. Hence, the lighting management system according to the present invention, and the user interface device thereof rendering the visual representation, are a beneficial technical tool that facilitates the health monitoring and reliability monitoring of a plurality of LED based lighting devices. The visual representation may thus represent a “health fingerprint” of the plurality of lighting devices, and a “one glance view” of the progression of the LED driver module health at population or fleet level of the lighting devices.

[0021] Hence, the user interface device renders a (single) visual representation reflecting the health of a plurality of lighting devices on fleet level, wherein multidimensional hyper data of the LED driver modules is purposefully transformed (by selecting the appropriate composite features) into points in the visual representation, wherein each point represents a respective driver module of the plurality of lighting devices.

[0022] All in all, the present invention provides a lighting management system wherein the maximum amount of information (of operational metrics) related to a LED driver module is persevered, while enabling a dynamic and human-interpretable visualization of said information. Therefore, the lighting management system according to the present invention satisfies a need in the field of health monitoring of lighting systems.

[0023] Said plurality of lighting devices may alternatively be phrased as a fleet of lighting devices, or a population of lighting devices. Said lighting devices may for example be a streetlighting devices. Said point may be phrased as a data point. Said visual representation may be phrased as a plot. Said LED driver module may alternatively be phrased as a LED driver. The driver module may comprise a driver or power source. The control system may alternatively be phrased as a controller. Said lighting device may alternatively be phrased as a light fixture. Alternatively, the driver module according to the present invention may comprise a light source, such as Light Emitting Diodes (LED) or a laser light source. Hence, the driver module may be a module comprising both power deliver, or power electronics, as well as the lighting modules arranged for providing illumination.

[0024] Alternatively phrased, each lighting device of the plurality of lighting devices comprises a respective driver module configured to measure values of operational parameters of a set of operational parameters, and to convey the measured values to the control system, wherein said first composite metric is calculated based on the measured values of the selected at least two first operational parameters; and wherein the second composite metric is calculated based on the measured values of the selected at least two second operational parameters.

[0025] As mentioned, each lighting device of the plurality of lighting devices comprises a respective driver module configured to determine values of operational parameters of a set of operational parameters, and to convey the determined values to the control system.

[0026] The driver module may alternatively be phrased as LED driver. It is known in the art that driver modules, such as modem LED driver modules, can collect vast amounts of data on various operational parameters. Hence, the driver module according to the invention is configured to obtain (driver) telemetry data. The driver module may use the telemetry data to obtain (or: calculate, or: determine) a set of operational parameters. Hence, thereby, the driver module according to the invention is configured to determine and / or measure values of operational parameters of a set of operational parameters.

[0027] The driver module according to the invention may comprise internal sensing means for sensing at least part of the set of operational parameters, and / or be in communication with external sensing means for sensing at least part of the set of operational parameters and obtain (i.e. receive or retrieve) said least part of the set of operational parameters from said external sensing means. For example, the lighting device comprising the driver module may also comprise said external sensing means.

[0028] In an embodiment, the set of operational parameters may comprise at least three operational parameters. Hence, the set of operational parameters comprises sufficient operational parameters to ensure that the at least two first operational parameters and the at least two second operational parameters are different, albeit with the possibility of overlap for one operational parameter. In examples, the set of operational parameters comprises at least four operational parameters. In an embodiment, not limited thereto, the set of operational parameters may comprise at least three of: (i) driver module input over voltage stress level; (ii) driver module input under voltage stress level; (iii) driver module lightning surge level; (iv) driver module over temperature; (v) driver module cold start stress; (vi) vibration level; (vii) lighting surge frequency / lighting strike frequency; (viii) bus voltage; (ix) ambient temperature level; (x) water ingress level; (xi) grid voltage transient; (xii) power level; (xiii) operational state of the LED light source associated with the driver module (e.g. standby or fully on).

[0029] It may be beneficial that when selecting the first and second composite features, the second composite feature (C2) contains as little information that is already contained in the first composite feature (Cl). At the same time, it may be beneficial to enable maximum amount of information is captured by the first composite feature (Cl) and the remaining maximum amount of information orthogonal thereto in the second composite feature (C2).

[0030] Hence, in an embodiment, the at least two second operational parameters are orthogonal to the at least two first operational parameters. Hence, the first composite feature may be substantially orthogonal to the second composite feature.

[0031] The control system may thus be configured to determine, from the set of operational parameters, at least two second operational parameters that are orthogonal to at least two first operational parameters, and then select said at least two first operational parameters from the set of operational parameters and select said at least two second operational parameters from the set of operational parameters. The control system may utilize physics-informed Al for said determining of which operational parameters are orthogonal.

[0032] For instance, one degradation mechanism, or failure mode, associated with a LED driver module is cold start stress, wherein a component on the PCB of the LED driver module is being stressed, deformed, or even ripped out during a cold start of the corresponding lighting device. The operational parameter of driver module cold start stress, as will be elaborated in more detail in the present application, will for example be orthogonal (i.e. largely uncorrelated) to an electronics related failure mode described in the present application.

[0033] As mentioned, each lighting device of the plurality of lighting devices comprises a respective driver module configured to determine values of operational parameters of a set of operational parameters, and to convey the determined values to the control system. The control system is configured to obtain the determined values from each respective driver module of the plurality of lighting devices. In an embodiment, each respective driver module may be configured to continually and / or periodically determine values of operational parameters of a set of operational parameters, and to convey the determined values to the control system.

[0034] In an embodiment, each respective driver module may be configured to incidentally determine values of operational parameters of a set of operational parameters, for example based on a trigger event, and to convey the determined values to the control system.

[0035] In an embodiment, the control system may be configured to obtain, either receive or retrieve, for a plurality of instances of time, from the respective driver module of each lighting device of the plurality of lighting devices, the determined values from each respective driver module of the plurality of lighting devices.

[0036] The control system may be in wired communication with the plurality of lighting devices, and / or in wireless communication with the plurality of lighting devices, or both. Said communication may for example be via DALI, ethemet, Lo-Ra, PoE, radiofrequency, LTE, 4G, 5G, other cellular, or optical communication modalities, etc.

[0037] In an embodiment, each respective driver module of the plurality of lighting devices may comprise a wireless communication unit configured to convey the determined values to the control system via wireless communication.

[0038] In an embodiment, each respective driver module of the plurality of lighting devices may comprise a wireless communication unit configured to convey the first composite metric (Cl) and the second composite metric (C2) to the control system via wireless communication.

[0039] In an embodiment, the control system may be configured to poll each respective driver module of the plurality of lighting devices to obtain said determined values. Hence, the control system may be configured to retrieve the determined values from each respective driver module of the plurality of lighting devices. Said polling may be performed continually and / or periodically.

[0040] As mentioned, each respective driver module conveys the determined values to the control system. The control system may perform the processing of the determined values - as indicated with the steps (i) to (iv) above - centrally, or locally.

[0041] Said control system may for example be remote and separate from the plurality of lighting devices. Said control system may for example be part of a lighting device of the plurality of lighting devices, thereby serving as a master node for the remaining lighting devices of the plurality of lighting devices. Central processing may be advantageous, because all processing is done at a single location. Hence, in an embodiment, the control system is a central controller configured to obtain the determined values from each respective driver module of the plurality of lighting devices, and wherein the central controller is configured to (v) convey a signal indicative of the first composite metric (Cl) and the second composite metric (C2) to the user interface device. Such an embodiment may be advantageous, as the central controller obtains all determined values and calculates the first composite metric (Cl) and the second composite metric (C2) centrally for all of the driver modules. Said central controller may for example be a (backend) server.

[0042] Hence, in a related embodiment, the central controller may be arranged separately (and / or remotely) from the plurality of lighting devices. Alternatively, in a related embodiment, the central controller may be arranged in a single master lighting device of the plurality of lighting devices. Such a master lighting device may be a master node amongst the plurality of lighting devices, which comprises the computational power to perform the processing for the plurality of lighting devices, such that only one of the lighting devices of the plurality of lighting devices (i.e. only the master lighting device) needs to be equipped with additional processing power, which may save costs.

[0043] Local processing may be advantageous, because all processing is distributed amongst local processing nodes, thereby relieving the need to equip a single location with sufficient processing power. Hence, in an embodiment, the control system comprises a plurality of local controllers; wherein each local controller of the plurality of local controllers is associated with a respective lighting device of the plurality of lighting devices; wherein each local controller is configured to obtain the determined values from the respective driver module of the respective lighting device associated therewith; wherein each local controller is configured, for said respective driver module associated therewith, to: (i) select the at least two first operational parameters from the set of operational parameters, and (ii) calculate the first composite metric (Cl) based on the determined values of the selected at least two first operational parameters; (iii) select the at least two second operational parameters from the set of operational parameters, wherein the at least two second operational parameters are different from the at least two first operational parameters, and (iv) calculate the second composite metric (C2) based on the determined values of the selected at least two second operational parameters.

[0044] In examples, said control system may comprise a (local) controller mounted on a housing of the lighting device or housed within the housing of the lighting device. Such mounting may be via aNEMA or Zhaga socket. Said local controller may thus be a outdoor lighting controller.

[0045] In a related embodiment, the control system comprises a central controller in communication with the plurality of local controllers; wherein the central controller is configured, for each respective driver module of the plurality of lighting devices, to obtain the first composite metric (Cl) and the second composite metric (C2) from the plurality of local controllers.

[0046] In an embodiment, the control system may be configured to poll each local controller of the plurality of local controllers (and / or each respective driver module of the plurality of lighting devices) to obtain said first composite metric (Cl) and the second composite metric (C2). Hence, the control system may be configured to retrieve the first composite metric (Cl) and the second composite metric (C2) from each respective driver module of the plurality of lighting devices. Said polling may be performed continually and / or periodically.

[0047] Yet even further, in an embodiment, each local controller is configured to transmit said first composite metric (Cl) and the second composite metric (C2) to the central controller and / or user interface device based on a value of said first composite metric (Cl) and / or a value of said second composite metric (C2). For example, only the first composite metric exceeding a first value threshold and / or the second composite metric with a value exceeding a second value threshold are transmitted, such that only relevant composite metrics may be considered for rendering in the visual representation. Such an embodiment may be advantageous to limit communication cost with the backend, but still keep the richness in data, because the telemetry data is communicated in the condensed composite metrics.

[0048] Alternatively, in an embodiment, each local controller is configured to set a flag feature if a value of said first composite metric (Cl) and / or a value of said second composite metric (C2) exceeds a predetermined flag feature threshold, wherein the central controller may be configured to poll each local controller of the plurality of lighting devices and obtain said first composite metric (Cl) and the second composite metric (C2) from the local controllers that have set the flag feature.

[0049] As mentioned, the control system is configured, for each respective driver module of the plurality of lighting devices, to: (i) select at least two first operational parameters from the set of operational parameters, and (iii) select at least two second operational parameters from the set of operational parameters, wherein the at least two second operational parameters are different from the at least two first operational parameters. Said selection may be performed by the control system in multiple ways.

[0050] In an embodiment, the at least two first operational parameters and / or the at least two second operational parameters may be preselected. For example, the control system may comprise predefined rules which parameters to select as the two first operational parameters and / or which parameters to select as the at least two second operational parameters. Such predefined rules may be stored (or: provided, or: installed, or: commissioned) in the control system during installation and / or configuration of the lighting management system and corresponding plurality of lighting devices.

[0051] In a different embodiment, the control system may comprise a physics informed Artificial Intelligence (Al) algorithm configured to select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters. For example, the physics informed Al algorithm may determine which operational parameters may significantly affect the health of the lighting device and / or driver module. For example, the Al algorithm may learn which operational parameter is increasingly deteriorating (e.g. relative to other parameters) and may select said operational parameters for a composite feature. The Al algorithm may also determine which parameters may be orthogonal to each other. Said Al algorithm may also determine which parameters are relevant based on analysing historical, or empirical, or real-time data related to health monitoring - which data may indicate when, how, why certain lighting devices have failed.

[0052] In a different embodiment, the control system may be configured to determine an installation location for the plurality of lighting devices, and wherein the control system is configured to select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters based on said determined installation location. Said installation location may apply for the plurality of lighting devices as a whole (e.g. as a fleet, as a project, or as a population). Said installation location may alternatively be phrased as geographic location, or the same geographic location.

[0053] Such an embodiment may be advantageous, because each installation location or each (same) geographic location may cope with different environmental conditions influencing the health and reliability of the plurality of lighting devices, and therefore each installation location or each (same) geographic location may require a different selection of the at least two first operational parameters and the at least two second operational parameters from the set of operational parameters.

[0054] For example, considering the installation location for the plurality of lighting devices to be a metropolitan area of a city, different cities may cope with different environmental conditions influencing the health and reliability of the plurality of lighting devices: such as Miami in Florida coping with high humidity and large number of lightning strikes affecting the respective lighting devices; such as Phoenix in Arizona coping with excessive high ambient temperatures, ingress of dust, and low number of lighting strikes, affecting the respective lighting devices; and such as Anchorage in Alaska coping with excessive low ambient temperatures (sub-zero freezing temperatures) and many burning hours during winter.

[0055] Moreover, for example, the characteristics of lightning strikes - e.g. represented by the parameters of average amplitude, strikes per year per pole, average duration of lightning strikes, etc. - as experienced by a streetlighting project installed in Florida may be very different than the characteristics of lightning strikes for streetlighting project installed in Alaska. Namely, Arctic and Antarctic regions are known to experience less, and less severe lightning strikes compared to tropical areas and inland areas. In the United States, the west coast has the fewest lightning strikes, while Florida is championing with thunderstorms and the most lightning strikes due to the subtropical climate conditions and proximity to the ocean.

[0056] Therefore, since installation location is relevant for health monitoring of the plurality of lighting devices, the control system determining the installation location for the plurality of lighting devices (which installation location may be referred to as the same installation location, e.g. a geographic region or area, or city), and then selecting the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters based on said determined installation location may be advantageous.

[0057] For example, for Miami in Florida, the at least two first operational parameters or the at least two second operational parameters from the set of operational parameters may be two of: the experienced lightning strike frequency, water ingress level, and driver module lightning surge level. For example, for Anchorage in Alaska, the at least two first operational parameters or the at least two second operational parameters from the set of operational parameters may be two of: driver module cold start stress, ambient temperature level, and vibration level. For example, for Phoenix in Arizona, the at least two first operational parameters or the at least two second operational parameters from the set of operational parameters may be two of: driver module over temperature, ambient temperature level, and power level.

[0058] In a different embodiment, the control system may be configured to: receive a user input signal indicative of the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters; wherein the control system is configured to select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters based on said user input signal.

[0059] In a different embodiment, the control system may be configured to determine a common feature of the plurality of lighting devices, and wherein the control system is configured to select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters based on said determined common feature of the plurality of lighting devices; wherein said common feature is at least one of: a nominal input voltage of the plurality of lighting devices, a type of the plurality of lighting devices, a driver module type of the plurality of lighting devices, an average age of the plurality of lighting devices, a stock keeping unit (SKU) of the driver module, a weather condition, a current season, a lifetime of the plurality of lighting devices.

[0060] Still referring to the lighting management system according to the invention. In an embodiment, the visual representation may be a scatter plot. In examples, said scatter plot may be a two-dimensional scatter plot.

[0061] However, in other examples, said scatter plot may be a three-dimensional scatter plot. For example, said user interface device may be a virtual reality, or mixed reality, or augmented reality headset with spatial computing, that is configured to render a three- dimensional scatter plot. In alternative embodiments, said visual representation may be a pixel heat map.

[0062] In an embodiment, the visual representation comprises a first user interface element configured to delineate a region indicative of driver module risk or failure. In an embodiment, the first user interface element is a highlighted region within the visual representation, a contour within the visual representation, and / or a line within the visual representation. As partly mentioned, the control system is configured to calculate - at each moment in time - a first composite metric (Cl) and a second composite metric (C2) based on the obtained determined values of the respective operational parameters from each driver module. Hence, the first composite metric (Cl) and the second composite metric (C2) may be time-dependent metrics (i.e. that dynamically change with time). This enables monitoring the health (and health development) of a plurality of lighting devices over time, e.g. during their (product) lifetime.

[0063] Hence, in an embodiment, each respective driver module is configured to determine values of operational parameters of a set of operational parameters at a first moment in time (Tl) and at a second moment in time (T2); wherein the control system (e.g. either the central controller or the plurality of local controllers, as mentioned above) is configured, for each respective driver module of the plurality of lighting devices, to: (ii) calculate the first composite metric (Cl) based on the determined values of the selected at least two first operational parameters at the first moment in time (Tl) and at the second moment in time (T2); and (iv) calculate the second composite metric (C2) based on the determined values of the selected at least two second operational parameters at the first moment in time (Tl) and at the second moment in time (T2); wherein the visual representation is a time-dependent visual representation comprising a first visual representation indicative of the first moment in time and a second visual representation indicative of the second moment in time; wherein the user interface device is configured to: for each respective driver module of the plurality of lighting devices plot a first point within the first visual representation corresponding to the first composite metric and the second composite metric at the first moment in time, and plot a second point within the second visual representation corresponding to the first composite metric and the second composite metric at the second moment in time.

[0064] In an embodiment, the control system may be configured to: calculate the first composite metric (Cl) with a fixed first composite metric formula that is a function of the determined values of the selected at least two first operational parameters; calculate the second composite metric (C2) with a fixed second composite metric formula that is a function of the determined values of the selected at least two second operational parameters.

[0065] In an embodiment, the control system may calculate the first composite metric (Cl) based on the weighted sum of the determined values of the selected at least two first operational parameters; wherein the control system calculates the second composite metric (C2) based on the weighted sum of the determined values of the selected at least two second operational parameters.

[0066] In an embodiment, the control system is configured to select cold start stress level and vibration level from the set of operational parameters, and configured to calculate the first composite metric (Cl) based on the determined values of the selected cold start stress level and the vibration level; wherein the control system is configured to select lighting strike frequency and driver module input under voltage stress level from the set of operational parameters, and configured to calculate the second composite metric (C2) based on the determined values of the selected lighting strike frequency and driver module input under voltage stress level.

[0067] For example: A LED driver module may typically have a potting material. Said potting material in the LED driver module comprises a glass transition temperature, below which it becomes very solid. A solidified potting has a thermal expansion coefficient that is different from the electronic components and / or the PCB onto which electronic components are present. Hence, a thermal difference coefficient exists between the potting material and the electronic components and / or the PCB onto which electronic components are present. As the LED driver module setting changes, for example switching ON a lighting device (in winter) having initially a very cold LED driver module, the mismatch in thermal expansion coefficients between the potting and the components and / or the PCB induces mechanical stress on the components and / or the PCB, which forces may cause said components, or solder joints, or even the PCB to break or crack. For instance, the applicant has found that during power-up at cold temperature in Alaska, the MOSFET SMD components will heat up faster than the surrounding crystallized potting, which leads to mechanical stress on the MOSFETs, and such damage may lead to reduced lifetime and modes of failure.

[0068] Similarly, extreme-cold temperature exposure of a LED driver module as such, even without powering up the driver module and the light source, may already result in various components to be stressed and possibly pulled out of the PCB, because the potting asphalt of the LED driver module crystalizes at low temperature and solidifies, thereby resulting in thermal stress to the surrounding components in contact therewith. The applicant has experienced this for SMD diodes and SMD capacitors, for example.

[0069] Hence, to calculate the cold start stress level, the control system may obtain determined values related to the operational parameter of cold start temperature (i.e. the temperature right after the driver module has been powered up) to capture the information - or at least an indication - about the lowest temperature the LED driver module has reached in off-mode, the control system may obtain determined values related to the operational parameter of ambient temperature.

[0070] For example: Another known mechanism in degradation of electronics, and in particular LED driver module electronics, is vibration of the lighting device (or luminaire). Vibration may lead to flexing of the PCB within the LED driver module, or lead to mechanical forces loosening the components in LED driver module that are e.g. present on the PCB. Vibration may for example lead to a broken pin of a relatively heavy component, such as a transformer. Such vibration may for example be induced by traffic (e.g. heavy trucks) passing by the lighting device and associated LED driver module, or by heavy machinery close to the lighting device and associated LED driver module, or by a wind load and / or other similar meteorological phenomena. The vibration may for example be measured by a vibration sensor, that is associated with the LED driver module.

[0071] Hence, in the present embodiment, the control system is configured to select cold start stress level and vibration level from the set of operational parameters, and is configured to calculate the first composite metric (Cl) based on the determined values of the selected cold start stress level and the vibration level. The first composite metric (Cl) is thus associated with the overarching degradation mechanism of loose electronic components.

[0072] In a different embodiment, the control system is configured to select ambient temperature and power level from the set of operational parameters, and configured to calculate the first composite metric (Cl) based on the determined values of the selected ambient temperature and the power level; wherein the control system is configured to select driver module input over voltage stress level and driver module input under voltage stress level from the set of operational parameters, and configured to calculate the second composite metric (C2) based on the determined values of the selected driver module input over voltage stress level and driver module input under voltage stress level.

[0073] In an embodiment, the control system is configured to select ambient temperature and LED current ripple from the set of operational parameters, and configured to calculate the first composite metric (Cl) or the second composite metric (C2) based on the determined values of the selected ambient temperature and the LED current ripple.

[0074] In an embodiment, the control system is configured to select operational state of the LED light (e.g. standby vs. fully on), and LED current ripple from the set of operational parameters, and configured to calculate the first composite metric (Cl) or the second composite metric (C2) based on the determined values of the selected ambient temperature and the LED current ripple.

[0075] In an embodiment, the control system is configured to select ambient temperature and water ingress level from the set of operational parameters, and configured to calculate the first composite metric (Cl) or the second composite metric (C2) based on the determined values of the selected ambient temperature and the water ingress level.

[0076] In an embodiment, the control system is configured to select driver module input over voltage stress level and driver module input under voltage stress level from the set of operational parameters, and configured to calculate the first composite metric (Cl) or the second composite metric (C2) based on the determined values of the driver module input over voltage stress level and driver module input under voltage stress level.

[0077] Still referring to the lighting management system according to the invention. In an embodiment, the control system according to the invention is configured, for each respective driver module of a plurality of lighting devices, to: select at least two third operational parameters from the set of operational parameters, wherein the at least two third operational parameters are different from the at least two first operational parameters and the at least two second operational parameters, and calculate a third composite metric (C3) based on the determined values of the selected at least two third operational parameters.

[0078] In a related embodiment, the user interface device is configured to: obtain a signal indicative of the third composite metric (C3) from the control system; and for each respective driver module of the plurality of lighting devices change a dimension of the point that is plotted within the visual representation corresponding to the first composite metric and the second composite metric. In an embodiment, said dimension may be size; or in other words point size or the diameter of said point. Said point according to the invention that is plotted within the visual representation corresponding to the first composite metric and the second composite metric may be a bubble. Said dimension may then be a bubble size. In a different embodiment, said dimension may be color (of the point). In a different embodiment, said dimension may be a contour shape. Such embodiments with a third composite metric may be advantageous, as more information may be plotted within the visual representation, thereby also visualizing a third dimension of data ergonomically. In the embodiments comprising the third composite metric, said visual representation may be a three-dimensional visual representation, such as s three-dimensional scatter plot.

[0079] In aspects, the control system is configured, for each respective driver module of the plurality of lighting devices, to: (i) permanently select at least two first operational parameters from the set of operational parameters, and (ii) calculate a first composite metric (Cl) based on the determined values of the selected at least two first operational parameters; (iii) permanently select at least two second operational parameters from the set of operational parameters, wherein the at least two second operational parameters are different from the at least two first operational parameters, and (iv) calculate a second composite metric (C2) based on the determined values of the selected at least two second operational parameters. Hence, once the at least two first operational parameters and the at least two second operational parameters are permanently selected, the first composite metric (Cl) and the second composite metric (C2) are always calculated the same for each respective driver module of the plurality of lighting devices. A formula for calculating the first composite metric (Cl) and the second composite metric (C2) may be frozen permanently. Hereby, the phrase permanently meaning fixed for a predetermined period of time of at least 5 years.

[0080] This enables for example a human maintenance expert that is responsible for a streetlighting installation to learn to recognize the dominant failure signatures of LED driver modules specific to his streetlighting installation (in his city). Artificial Intelligence (Al) may thereby be used to first select which operational parameters will make up the first and second composite features, and its visualization in the visual representation, while from then onwards the human brain of the maintenance expert is helped by the user interface device to look onto the time-series of the visual representation (e.g. a time-dependent dynamic 2D scatter plot) to identify anormal LED driver modules in the streetlighting installation. An experienced streetlighting maintenance expert will look at the visual representation, e.g. a time-animated scatter plot, to recognize clusters with similar behaviour.

[0081] In aspects, the calculation of the first composite metric and / or the second composite metric, according to the present invention, may further be based on including general parameters other than said operational parameters. For example, said general parameters may be sensor measurements associated with the ambient and / or environment of the respective lighting device, but not necessarily of the respective lighting device itself. For example, such general parameters may be local windspeed, air quality (e.g. volatile organic compounds or dust), the number of human interactions with the lighting device (e.g. hooliganism).

[0082] It is further an object of the invention to provide an improved method, which at least alleviates the problems and disadvantages mentioned above. Thereto, the invention provides a method of light management of a plurality of lighting device, wherein each lighting device of the plurality of lighting devices comprises a respective driver module, wherein the method comprises: each respective driver module determining values of operational parameters of a set of operational parameters, and conveying the determined values to the control system; a control system obtaining the determined values from each respective driver module of the plurality of lighting devices; the control system, for each respective driver module of the plurality of lighting devices, (i) selecting at least two first operational parameters from the set of operational parameters, and (ii) calculating a first composite metric (Cl) based on the determined values of the selected at least two first operational parameters; the control system, for each respective driver module of the plurality of lighting devices, (iii) selecting at least two second operational parameters from the set of operational parameters, wherein the at least two second operational parameters are different from the at least two first operational parameters, and (iv) calculating a second composite metric (C2) based on the determined values of the selected at least two second operational parameters; a user interface device obtaining a signal indicative of the first composite metric (Cl) and the second composite metric (C2); the user interface device rendering a visual representation having a first composite metric axis and a second composite metric axis, and the user interface device, for each respective driver module of the plurality of lighting devices, plot a point within the visual representation corresponding to the first composite metric and the second composite metric. Thereby, advantages and / or embodiments applying to the system according to the invention may mutatis mutandis apply to said method according to the invention.

[0083] The invention further relates to a computer program product. Hence, the invention provides a computer program product comprising computer program code to perform the method according to the invention when the computer program product is run on a processing unit of the control system.

[0084] Thus, aspects of the invention may be implemented in a computer program product, which may be a collection of computer program instructions stored on a computer readable storage device which may be executed by a computer or control system. The instructions of the present invention may be in any interpretable or executable code mechanism, including but not limited to scripts, interpretable programs, dynamic link libraries (DLLs) or Java classes. The instructions can be provided as complete executable programs, partial executable programs, as modifications to existing programs (e.g. updates) or extensions for existing programs (e.g. plugins). Moreover, parts of the processing of the present invention may be distributed over multiple computers or processors. It is further an object of the invention to provide an improved controller, which at least alleviates the problems and disadvantages mentioned above. Thereto, the invention provides a controller for managing (or monitoring) a plurality of lighting devices each comprising a respective driver module configured to determine values of operational parameters of a set of operational parameters, wherein the controller is configured, for each respective driver module of a plurality of lighting devices, to: (i) select at least two first operational parameters from a set of operational parameters, and (ii) calculate a first composite metric (Cl) based on the determined values of the selected at least two first operational parameters; (iii) select at least two second operational parameters from the set of operational parameters, wherein the at least two second operational parameters are different from the at least two first operational parameters, and (iv) calculate a second composite metric (C2) based on the determined values of the selected at least two second operational parameters. Thereby, advantages and / or embodiments applying to the system according to the invention may mutatis mutandis apply to said controller according to the invention.

[0085] It is further an object of the invention to provide an improved lighting device, which at least alleviates the problems and disadvantages mentioned above. Thereto, the invention provides a lighting device comprising a local controller and a driver module, wherein the driver module is configured to determine values of operational parameters of a set of operational parameters, and to convey the determined values to the local controller; wherein the local controller is configured to (i) select at least two first operational parameters from the set of operational parameters, and (ii) calculate a first composite metric (Cl) based on the determined values of the selected at least two first operational parameters; (iii) select at least two second operational parameters from the set of operational parameters, wherein the at least two second operational parameters are different from the at least two first operational parameters, and (iv) calculate a second composite metric (C2) based on the determined values of the selected at least two second operational parameters. Thereby, advantages and / or embodiments applying to the system according to the invention may mutatis mutandis apply to said lighting device according to the invention. Said lighting device may alternatively be phrased a luminaire. Said lighting device may thus be a luminaire. Said lighting device or luminaire may comprise a light source for illuminating an outdoor environment.

[0086] In an embodiment, the local controller is configured to convey a signal indicative of the first composite metric (Cl) and the second composite metric (C2). In an embodiment, the local controller is configured to transmit the signal indicative of the first composite metric (Cl) and the second composite metric (C2) based on a value of said first composite metric and / or said second composite metric. For example, in an embodiment, the local controller is configured to transmit the signal indicative of the first composite metric (Cl) and the second composite metric (C2) if a value of said first composite metric and / or said second composite metric is within a predetermined threshold limit (e.g. exceeds a predetermined threshold value, or is below a predetermined threshold value).

[0087] For example, only the first composite metric exceeding a first value threshold and / or the second composite metric with a value exceeding a second value threshold are transmitted, such that only relevant composite metrics may be considered for rendering in the visual representation. Such an embodiment may be advantageous to limit communication cost with the backend, but still keep the richness in data, because the telemetry data is communicated in the condensed composite metrics.

[0088] For example, the lighting device may be installed in Anchorage Alaska, and at a location that experiences direct sunlight during the afternoon. This may prevent the lighting device to experience cold start stress problems when turning on in the evening, as the temperature of the lighting device was already relatively mild in the sunlight compared to a lighting device installed in the shade. However, at some point, the lighting device may experience no direct sunlight during the afternoon for various reasons, such as for example a newly erected building casting shade to the lighting device, a growing tree casting shade to the lighting device, or the movement of the sun causing periods of direct sunlight at a lower incidence angle, etc. Hence, in such situations, cold start stress may manifest. Thus, the local controller may select cold start stress level and vibration level from the set of operational parameters and calculate the first composite metric (Cl) based on the determined values of the selected cold start stress level and the vibration level. The lighting device may then convey a signal indicative of the first composite metric (Cl) and the second composite metric (C2) based on a value of said first composite metric. More specifically, the local controller may only transmit the first composite metric and the second composite metric if the first composite metric exceeds a threshold limit, i.e. exceeds a predetermined threshold value. Hence, when the lighting device experiences the above-mentioned situation, that may give rise to cold start stress, only then the first composite metric (Cl) is being conveyed. This enables limiting communication cost, to moments when such communication is most needed. Alternatively, in an embodiment, the local controller is configured to set a flag feature if a value of said first composite metric (Cl) and / or a value of said second composite metric (C2) exceeds a predetermined flag feature threshold, wherein local controller is configured to determine a condition wherein a third device polls the local controller for the first composite metric (Cl) and / or the second composite metric (C2); and wherein the local controller is configured to transmit (or: release) a signal indicative of the first composite metric (Cl) and / or the second composite metric (C2) if the flag feature is present and if said condition is determined.

[0089] In an embodiment, the local controller may periodically convey (e.g. transmit) the signal indicative of the first composite metric (Cl) and the second composite metric (C2) at a first frequency, wherein the local controller is configured to determine (or: set) the first frequency based on a value (or, alternatively: a history of values) of the first composite metric (Cl) and / or the second composite metric (C2). For example, in an embodiment, the local controller is configured to transmit the signal indicative of the first composite metric (Cl) and the second composite metric (C2) at a first frequency if a value of said first composite metric and / or said second composite metric is within a predetermined first threshold limit (e.g. exceeds a predetermined first threshold value, or is below a predetermined first threshold value), and at a second frequency if a value of said first composite metric and / or said second composite metric is within a predetermined second threshold limit (e.g. exceeds a predetermined second threshold value, or is below a predetermined second threshold value).

[0090] In an embodiment, the local controller may determine a value of total number of burning hours of the lighting device, and wherein the local controller may be periodically convey (e.g. transmit) the signal indicative of the first composite metric (Cl) and the second composite metric (C2) at a first frequency if said value is below a predetermine threshold limit (for example 25000 burning hours) and at a second frequency if said value is above a predetermined threshold limit (for example 25000 burning hours). In an embodiment, preferably, the second frequency is higher than the first frequency, and most preferably at least a factor 2 higher.

[0091] BRIEF DESCRIPTION OF THE DRAWINGS

[0092] The invention will now be further elucidated by means of the schematic nonlimiting drawings: Fig. 1 depicts schematically an embodiment of a lighting management system according to the invention;

[0093] Fig. 2 depicts schematically a visual representation rendered by a user interface device of the embodiment depicted in figure 1 ;

[0094] Fig. 3 depicts schematically an embodiment of a lighting management system according to the invention;

[0095] Fig. 4 depicts schematically an embodiment of a lighting management system according to the invention;

[0096] Fig. 5 depicts schematically a method according to the invention.

[0097] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0098] A lighting device may operate in various environments and experience different conditions - such as for example input voltage, ambient temperature, humidity, airflow, vibration, lightning strikes, mechanical stresses, etc. Such conditions also determine the health and lifetime of the lighting device.

[0099] For example, the input voltage of a LED driver module of a lighting device may experience an overshoot whenever other electrical loads connected to a same branch circuit are switched on or off. Such an overshoot may affect health and lifetime of the lighting device. Similarly, the lighting device switching from a utility’s electricity grid to a local energy generator may cause voltage overshoot or undershoot, thereby stressing the electronic components, and affecting health and lifetime of the lighting device.

[0100] Similarly, a lightning bolt may strike an electricity line nearby the lighting device and generate a high surge voltage at the input of the driver of the lighting device, which may affect health and lifetime of the lighting device.

[0101] For example, lighting devices may also experience unforeseen high temperatures of the driver module, e.g. due to their location, placement, or environmental conditions such as ambient temperature. It is thereby well known in the art that the predicted lifetime of a lighting device is typically halved with every ten-degree Celsius increase in temperature of the driver module, i.e. relative to a nominal driver case temperature for normal operation. Operating at such higher temperatures may thus limit lifetime.

[0102] Throughout this application, said case temperature of the driver module may also be considered as the temperature of the driver module.

[0103] Moreover, particularly for outdoor lighting, when a LED driver module is powered up at a very cold ambient temperature, components of the LED driver module may experience mechanical stress and malfunction, also known as cold start stress. For example, when a LED driver module is initially cold, the potting of the LED driver module may become crystalized, and when the LED driver module is powering up (and thereby heating up), said potting may mechanically stress the components in the LED driver module at powering up.

[0104] For example, when an electrical circuit with a plurality of LED lighting devices and associated driver modules is heavily loaded, driver modules at the end of a branch circuit may operate at undervoltage conditions. As most LED lighting devices operate at constant output power mode to keep light output consistent, an undervoltage condition will inevitably result in the electronics of the respective driver module to increase the input current, which will cause an over current in the driver module. For a nominal input voltage range 120-277V, a typical LED driver module is designed for an input voltage from 108V to 305V to cover plus-minus 10% variations in the electricity grid voltage. Operation outside of this range may cause substantial stress on the electronics, thereby affecting health and reducing lifetime.

[0105] All of the above conditions may impose electrical, thermal and / or mechanical stresses, which may cause (irreversible) damage and / or earlier failure of a lighting device and the driver module associated therewith.

[0106] Therefore, LED driver modules are configured to collect vast amounts of data on various operational parameters. Such operational parameters may for example be the input (mains) voltage, the surge voltage or current events, brown-outs, cold-start events, lightning strikes, the driver module temperature, the LED board temperature, etc.

[0107] Consequently, due to the availability of various data, health monitoring and reliability monitoring of a plurality of LED based lighting devices - such as a fleet of streetlights - has become easier and more common. However, the applicant has found that a single number is too simplistic to truly capture and communicate the complex health state of a modem LED driver module, while on the other hand a vast array of numbers becomes too complicated for human interpretation. It is also found that communication of such (driver) telemetry data to a backend is not free of communication cost.

[0108] Hence, there is a clear need for tools that increases the interpretability of driver module-reliability (and / or health) related data while (A) preserving the maximum amount of information (or operational metrics) of the LED driver module, and (B) enabling a dynamic and human-interpretable visualization of said information, and (C) preferably reducing the cost for communication doing so. The present invention meets these needs. Figure 1 depicts schematically, by non-limiting example, an embodiment of a lighting management system 100 according to the invention. The lighting management system 100 comprises a plurality of lighting devices 10, a control system 20 and a user interface device 30.

[0109] Said plurality of lighting devices 10 may be luminaires or fixtures, such as a fleet of street lighting fixtures. Here, still referring to the embodiment depicted in figure 1, the lighting devices are installed in a street lighting project in Anchorage Alaska, where ambient temperatures are relatively low and environmental conditions harsh.

[0110] To facilitate explaining the invention, the embodiment depicted in figure 1 comprises three lighting devices 11, 12, 13. Each lighting device 11, 12, 13 comprises a respective driver module 111, 121, 131.

[0111] Alternatively, the plurality of lighting devices may be any other plural number of lighting devices. The plurality of lighting devices may alternatively be phrased as a plurality of luminaires, or a plurality of light fixtures. The plurality of lighting devices may for example be a fleet of streetlights. The lighting devices may be LED lighting devices. Each lighting device of the plurality of lighting devices comprises a respective driver module. Said driver module may alternatively be phrased as a LED driver module, or LED driver. Each lighting device may comprise a single or multiple light engines configured to provide light source light and to illuminate an environment.

[0112] Still referring to figure 1, the respective driver module 111, 121, 131 is configured to obtain (e.g. collect, retrieve, or receive) telemetry data on a set 40 of operational parameters. The respective driver module 111, 121, 131 may also be configured to calculate said operational parameters based on the various telemetry data obtained, for example. Each driver module may comprise a processor suitable for such calculations.

[0113] Moreover, for example, not depicted, each driver module may comprise internal sensing means for sensing at least part of the set of operational parameters, and / or be in communication with external sensing means, for sensing at least part of the set of operational parameters and obtain (i.e. receive or retrieve) said least part of the set of operational parameters from said external sensing means. Said external sensing means may be part of the respective lighting device.

[0114] The set 40 of operational parameters comprises at least three operational parameters. Still referring to figure 1, to facilitate explaining the invention, the set 40 of operational parameters comprises four operational parameters. Namely, a first parameter (Pl) being cold start stress, a second parameter (P2) being vibration level, a third parameter (P3) being driver module input under voltage stress level, and a fourth parameter (P4) being driver module over voltage stress level.

[0115] Regarding the fourth parameter (P4), input over voltage stress level (or: input over voltage health degradation), this parameter may be calculated by the driver module (based on obtained telemetry data inputs). Thereby, it is noted that the following calculation example is provided for a driver module with a nominal input voltage range of 120V - 277V, wherein the typical input voltage is between 108V - 305V to cover plus-minus 10% of variations. Hence, this example is provided for a driver module with a nominal input voltage between 108V - 305V but can mutatis mutandis be applied to other input ranges, such as 374V or 480V drivers.

[0116] When the input voltage of a LED driver module is above 305V, the stress level can be expressed with an equation. Whenever the input voltage is 50% above max nominal, with 1 cycle (0.0167ms), or 10% above max nominal with 50k hours, the corresponding stress level and hence health impact on the driver module is considered very high. To calculate the input over voltage stress level, driver telemetry data is retrieved by the driver module on the input voltage, as well as the logarithm of the duration thereof in seconds. In practice, the duration of an overvoltage event can range between 0.01667ms to 50.000 hours (1.8xl0A8 seconds). The fourth parameter (P4) being driver module over voltage stress level (i.e. a feature indicative of the overvoltage-induced driver-health degradation) can be expressed by the following equation: lov= a + b * Vin+ c * log10(t)

[0117] Thereby: lov is the driver module over voltage stress level. Vin is the input voltage in percentage above max nominal. For example, considering a driver module with a max nominal input voltage of 277V, then the value of 10% means 305V - which is 10% higher than max nominal 2T1N. The variable t is the over voltage duration in seconds. The equation further contains the constants a, b, and c. Said constants may be predefined and / or prestored in the driver module. For instance, choosing a = -0.4878; b = 24.390, c = 0.97236. Other values for the constants may be envisioned as well. Said three constants may be determined by setting boundary conditions.

[0118] Similarly, regarding the third parameter (P3), input under voltage stress level (or: input under voltage health degradation), this parameter may be calculated by the driver module (based on obtained telemetry data inputs). Under voltage conditions frequently occur if a lighting device (e.g. a streetlight) is located on a heavily loaded electrical circuit and this specific lighting device is located at the very end of a branch circuit thereof. Thereby, it is noted that the following calculation example is again provided for a driver module with a nominal input voltage range of 120V - 277V, wherein the typical input voltage is between 108V - 305V to cover plus-minus 10% of variations.

[0119] The third parameter (P3), being the input under voltage stress level, may be calculated with the same formula as the input over voltage stress level, but with different boundary conditions and constants. Namely:

[0120] Iuv= a + b * Vin+ c * log10(t)

[0121] Thereby: Iuv is the driver module under voltage stress level. Vin is the input voltage in percentage above max nominal or below min nominal. For example, considering a driver module with a min nominal input voltage of 120V, then the value of -10% means 108V - which is 10% lower than min nominal 120V. The variable t is the over voltage duration in seconds. The equation further contains the constants a, b, and c. Said constants may be predefined and / or prestored in the driver module. For instance, choosing a = -1.5611 ; b = 33.333, c = 0.99667. Other values for the constants may be envisioned as well. Said three constants may be determined by setting boundary conditions.

[0122] Regarding the second parameter (P2), vibration level, this parameter may be calculated by the driver module based on obtained telemetry data inputs. For example, the driver module may obtain vibration measurements, or vibration data, from a sensing means such as a vibration sensor.

[0123] Regarding the first parameter (Pl), cold start stress, this parameter may be calculated by the driver module (based on obtained telemetry data inputs). For example, the (LED) driver module retrieves telemetry data on the temperature of the (LED) driver just before the cold-start, and how many times the (LED) driver module has been started at a temperature below a predetermined threshold value (i.e. cold-start). Namely, a typical LED driver survives multiple starts under a specified minimum temperature, e.g. 2000 starts under minus (-) 40 degrees Celsius; but will only survive a single start under a minimum temperature, e.g. a single start under minus (-) 55 degrees Celsius. Hence, the first parameter (Pl) being cold start stress can be expressed by the following equation:

[0124] Ic= a + b * T + c * N Thereby: Ic is the driver module cold start stress (level). T is the start temperature of the LED driver (i.e. powering on). N is the number of starts under said temperature T. The equation further contains the constants a, b, and c. Said constants may be predefined and / or prestored in the driver module. For instance, choosing a = 26.672; b = 0.667, c = 0.005. Other values for the constants may be envisioned as well. Said three constants may be determined by setting boundary conditions and electronics and / or lighting experts. Hence, as mentioned, the set 40 of operational parameters four operational parameters. Namely, a first parameter (Pl) being cold start stress, a second parameter (P2) being vibration level, a third parameter (P3) being driver module input under voltage stress level, and a fourth parameter (P4) being driver module over voltage stress level.

[0125] Alternatively, said set of operational parameters may comprise at least three of: (i) driver module input over voltage stress level; (ii) driver module input under voltage stress level; (iii) driver module lightning surge level; (iv) driver module over temperature; (v) driver module cold start stress; (vi) vibration level; (vii) lighting surge frequency / lighting strike frequency; (viii) bus voltage; (ix) ambient temperature level; (x) water ingress level;

[0126] (xi) grid voltage transient; (xii) power level; (xiii) operational state of the LED light source associated with the driver module (e.g. standby or fully on).

[0127] The parameters of: (iii) driver module lightning surge level, (iv) driver module over temperature, (ix) ambient temperature, (x) water ingress level (or humidity level), and

[0128] (xii) being power level will be explained in more detail below with respect to the embodiment depicted in figure 2 but may mutatis mutandis apply as alternative operational parameters for the embodiment depicted in figure 1.

[0129] Furthermore, for example, the first composite metric of the embodiment depicted in figure 1 may alternatively be determined by additionally including the parameter of ambient temperature. Namely, for example, the applicant has recognized that cold ambient temperatures induce abnormal waveforms in a LED driver, which degrade the health of the electronics components. For instance, electrolytic capacitors in cold temperature will temporarily degrade to almost zero value capacitance as the electrolyte crystallizes and consequently the ESR value of the capacitor becomes high. Hence, at low temperatures, the LED driver will output a huge external ripple on the LED components (at the same time an LED driver exposed to very low temperatures will suffer from high internal ripples). The huge internal and external ripples will damage the semiconductor components of the LED driver module and LED board. This may lead to visible malfunction in the illumination task of the lighting device (the applicant has observed that at low temperatures, a LED driver output current may toggle between on and off, thereby resulting in visible light flashes from the lighting device. It is however noted, after start, when a LED driver has been running for a period of time, the crystallized electrolyte will liquidize, and the capacitor will recover to its nominal capacitance value.

[0130] Moreover, the aforementioned electrolytic capacitor is used in many lighting device designs to clamp the DC bus voltage of the driver. If the ESR of the LED driver' s electrolytic capacitor is very high due to an extremely low ambient temperature, then this voltage clamping is not done very effectively, and any voltage surge present on the mains wires (e.g. due the utility company switching a capacitor bank in the grid) may undesirably lead to an increase of the bus voltage of the LED driver. Such increase in voltage may also affect the health of the LED driver and lighting device as such.

[0131] Hence, the operational parameter of ambient temperature may be relevant for health monitoring of a lighting device installed in Anchorage, Alaska - where ambient temperatures are low and lighting devices experience cold-starts.

[0132] The remaining operational parameters mentioned in the present application may similarly be calculated by lighting experts and / or driver experts, based on existing models for lighting device reliability, lighting device lifetime, and driver module and / or lighting device health degradation.

[0133] Hence, considering the above, the control system 60 is configured to calculate the first composite metric Cl with a fixed first composite metric formula that is a function of the determined values of the selected at least two first operational parameters; and to calculate the second composite metric C2 with a fixed second composite metric formula that is a function of the determined values of the selected at least two second operational parameters.

[0134] In examples, the control system calculates the first composite metric Cl based on the weighted sum of the determined values of the selected at least two first operational parameters; wherein the control system calculates the second composite metric C2 based on the weighted sum of the determined values of the selected at least two second operational parameters. For example: c w1P1+ w2P2

[0135] 1w + w2

[0136] Thereby: Ci is a first composite feature. C2 is a second composite feature. Pi, P2, P3, and P4 are a first, second, third, and a fourth operational parameter respectively. The factors wi, W2, W3, W4 are a first, second, third, and a fourth weighing factor respectively. Other weighing factors, and formulae for determining a composite feature, may be envisioned similarly.

[0137] All in all, still referring to figure 1, the respective driver module 111, 121, 131 is configured to determine - for example measure or calculate - values of a set 40 of said operational parameters Pl, P2, P3, P4. Each respective driver module 111, 121, 131 is configured to convey - for example transmit, release, make available or provide - said determined values to the control system 20. Thus, the control system 20 obtains (receive or retrieve) said determined values. Each respective driver module 111, 121, 131 of the plurality of lighting devices 11, 12, 13 may therefore comprise a communication unit configured to convey said determined values (or: the telemetry data as such) to the control system 20. Said communication unit may convey said determined values wirelessly or via a wired connection with the control system. In some examples, the control system may poll (e.g. periodically or incidentally) each respective driver module of the plurality of lighting devices to obtain said determined values.

[0138] Still referring to the embodiment depicted in figure 1, the control system 20 is arranged separately from the plurality of lighting devices 11, 12, 13. Here, the control system is a backend controller communicatively coupled to the plurality of lighting devices. The backend controller may for example be communicative coupled via a known radiofrequency modality or via a known wired communication means. Said communication may for example be via DALI, ethemet, Lo-Ra, PoE, radiofrequency, LTE, 4G, 5G, other cellular, or optical communication modalities, etc.

[0139] In alternative examples, not depicted, the control system 20 may also be embodied in in a single master lighting device of the plurality of lighting devices, such that the central intelligence of the lighting management system is within a master node, receiving data from slave nodes. Yet alternatively, the control system may be at least partly located within the driver module itself. The control system 20 is then configured, for each respective driver module 111, 121, 131 of the plurality of lighting devices 11, 12, 13, to perform the steps (i), (ii), (iii), and (iv) below.

[0140] Namely, the control system 20 is configured to (i) select at least two first operational parameters 41 from the set of operational parameters. Here, the control system 20 (purposefully) selects the first operational parameter Pl and the second operational parameter P2 - being cold start stress and vibration level respectively - as the at least two first operational parameters 41. The control system 20 is then configured to (ii) calculate a first composite metric Cl based on the determined values of the selected at least two first operational parameters 41. Namely, here, the control system 20 calculates said first composite metric Cl based on the determined values of the selected cold start stress and the vibration level.

[0141] Similarly, the control system 20 is configured to (iii) select at least two second operational parameters 42 from the set of operational parameters. Here, the control system 20 (purposefully) selects the third operational parameter P3 and the fourth operational parameter P4 - being driver module input under voltage stress level and driver module input over voltage stress level respectively - as the at least two second operational parameters 42. The control system 20 is then configured to (iv) calculate a second composite metric C2 based on the determined values of the selected at least two second operational parameters 42. Namely, here, the control system 20 calculates said second composite metric C2 based on the determined values of the selected driver module input under voltage stress level and driver module input over voltage stress level.

[0142] Thereby, the at least two second operational parameters 42 are different from the at least two first operational parameters 41, thereby making the first composite metric Cl and the second composite metric C2 different from each other. Here, the first composite metric Cl is related to mechanical degradation, failure and health, while the second composite metric C2 is related to more electronic degradation, failure and health. Therefore, as the second composite feature C2 contains as little information that is already contained in the first composite feature Cl, the at least two second operational parameters are substantially orthogonal to the at least two first operational parameters, which - in the present example - beneficially enables a maximum amount of information being captured by the first composite feature Cl and the remaining maximum amount of information orthogonal thereto in the second composite feature C2. Still referring to the embodiment depicted in figure 1, more specifically, said at least two first operational parameters 41 and the at least two second operational parameters are preselected or preconfigured, and e.g. stored in the control system. This may for example be done by a lighting expert, knowing that the plurality of lighting devices 11, 12, 13 are installed in Anchorage Alaska. This may for example be done during production of the lighting devices and / or the driver modules, and / or during commissioning / installation.

[0143] However, in alternative embodiments, the selection of the at least two first operational parameters and the at least two second operational parameters may be done alternatively.

[0144] For example, the control system is configured to: receive a user input signal indicative of the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters; wherein the control system is configured to select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters based on said user input signal.

[0145] For example, the control system is configured to determine an installation location for the plurality of lighting devices. Namely, in the present example, the control system determines that the plurality of lighting devices is installed in Anchorage Alaska, for example by obtaining their GPS location, or matching their unique identifier to an installation list indicative of which uniquely identified lighting devices are installed where in the world. The control system is subsequently configured to select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters based on said determined installation location. For example, for a plurality of lighting devices installed in Anchorage Alaska, the at least two first operational parameters and the at least two second operational parameters may be selected differently compared to a plurality of lighting devices installed in Miami Florida, the latter for example more focussing on capturing more lighting strike related degradation / failure modes with the second composite metric, and moisture related degradation / failure modes with the first composite metric.

[0146] For example, the control system may comprise a physics informed Artificial Intelligence (Al) algorithm configured to select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters. For example, the control system is configured to determine a common feature of the plurality of lighting devices, and wherein the control system is configured to select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters based on said determined common feature of the plurality of lighting devices; wherein said common feature is at least one of: a nominal input voltage of the plurality of lighting devices, a type of the plurality of lighting devices, a driver module type of the plurality of lighting devices, an average age of the plurality of lighting devices, a stock keeping unit (SKU) of the driver module, a weather condition, a current season, a lifetime of the plurality of lighting devices.

[0147] The latter example can be elaborated further. For example, the common feature may be a Stock Keeping Unit (SKU) of the driver module. For example, a driver module may be a 110-277V driver, or a 277-480V driver. The input voltage operating range may thus differ. The components may inherently differ as well. For example, based on empirical findings, a capacitor inside a batch of drivers of company “MU” may be weaker than a capacitor inside a batch of drivers from company “IO”. The driver modules with an SKU related to components of the company “MU” may thus require close monitoring and a purposefully selected set of operational parameters to monitor. Similarly, the common feature may be the input voltage of the driver module. The applicant provides driver modules for the North American market with a nominal input of 120V, 208V, 240V, 277V. 347V, 480V, for example. The most common nominal input voltage range of a LED driver is between 120V and 277V. The inventors have found that lightning strikes may affect 120-277V driver modules differently than 277-480V driver modules, wherein the latter 277-480V driver module appears to be less susceptible to lightning related damage. Hence, when the control system selects the at least two first operational parameters to construe the first composite feature and selects the at least two second operational parameters to construe the second composite feature, the control system may select lightning damage related operational parameters for the 120-277V driver modules, while other damage related operational parameters may be selected for the 277-480V driver modules, e.g. over temperature.

[0148] Similarly, the common feature may be a type of driver module, which characterizes a particular LED driver design or architecture. For example, the selection of the operating parameters for determining the first composite metric and / or the second composite metric may be based on said type of driver module, or in particular type of LED driver. For example, a first LED driver design may use a MOV (Metal Oxide Varistor) surge suppression device, which the applicants have found is typically sensitive to the accumulated surge energy over time, and which may perform badly at higher temperature and / or higher mains input voltages (due to an extra leakage current further increasing the temperature of the MOV). Another type of driver module, having a different LED driver design, may use TVS (Transient Voltage Suppression) diodes that have a failure mechanism which is more related to the absolute temperature, but which are less harmed by repeated surge events. Hence, based on the type of driver module, the control system according to the present invention may advantageously select temperature-related and mains-input-related operational parameters to determine (e.g. calculate) a composite metric for a driver type using a MOV, or may select only temperature-related operational parameters to determine (e.g. calculate) said composite metric for a driver type using a TVS. Said type of driver module may alternatively be a driver identifier.

[0149] Yet even further, the common feature may be a current season. The composite features determined for summer may be different for winter. This enables the maintenance person to better understand the seasonal effects on LED driver health. For example, for a location such as Florida, the summer season gives rise to driver health degradation due to lightning strikes, while in the winter season the ambient temperature transitions are the most prominent degradation mechanism.

[0150] Yet even further, a LED driver has typically 50k hours of lifetime. During the earlier part of the installed lifetime, failure mechanisms related to drastic events such as lightning strikes, brown-outs, cold-starts are the most important mechanisms for LED driver failure or degradation. During the later part of the installed lifetime, failure mechanisms related to wear and tear becomes more dominant. Therefore, the control system may be configured to select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters based on said determined common feature of a lifetime of the plurality of lighting devices, such as the number of hours of operation.

[0151] All in all, still referring to the embodiment depicted in figure 1, the lighting management system 100 according to the present invention advantageously creates a first composite metric Cl and a second composite metric C2 respectively from differently selected at least two operational parameters 41, 42. This condenses the obtained determined values, hence condenses the information pertaining to the health of each driver module 111, 121, 131.

[0152] The control system 100 is further configured to convey a signal 29 indicative of the first composite metric Cl and the second composite metric C2 to the user interface device 30. The user interface device 30 may for example be a computer, a display, a smartphone, a console, a tablet, smart glasses, a VR-headset, mixed reality headset, augmented reality device, etc. The signal may for example be a wired or a wireless signal.

[0153] The user interface device 30 obtains the signal 29 indicative of the first composite metric Cl and the second composite metric C2 from the control system 20. The user interface device 30 subsequently renders a visual representation 33. Here, the visual representation 33 is a scatter plot. The scatter plot may preferably be two dimensional. The visual representation - i.e. the scatter plot - comprises a first composite metric axis 31 and a second composite metric axis 32. The first composite metric axis 31 is the X-axis of the scatter plot, with the range representing values which the first composite features Cl of each respective driver module may take. The second composite metric axis 32 is the Y-axis of the scatter plot, with the range representing values which the second composite features C2 of each respective driver module may take.

[0154] Still referring to figure 1, the user interface device 30 is configured, for each respective driver module 111, 121, 131 of the plurality of lighting devices 11, 12, 13, to plot a point 331, 332, 333 within the visual representation 33 corresponding to the first composite metric Cl and the second composite metric C2 of the respective driver module 111, 121, 131.

[0155] Moreover, albeit optionally, as depicted in the present embodiment, the user interface device 30 is configured to plot a first user interface element 34 in the visual representation 33. Hence, the visual representation 33 comprises a first user interface element 34. The first user interface element 34 is configured to delineate a region 35 indicative of driver module risk or failure. Here, first user interface element 34 is a highlighted region 341 within the visual representation 33, and a line 342 within the visual representation 33, but may alternatively be a contour within the visual representation. Hence, a point 333 located within said region 35 indicates that the corresponding and / or associated driver module 131 may have deteriorated and has reduced lifetime, or in other words is closer to (expected) failure.

[0156] Hence, the user interface device 30 advantageously renders a visual representation 33 having a first composite metric axis 31 and a second composite metric axis 32, and for each respective driver module 111, 121, 131 of the plurality of lighting devices 11, 12, 13 plots a point 331, 332, 333 within the visual representation 33 corresponding to the first composite metric Cl and the second composite metric C2. This ensures that the determined values, which are condensed in the first (Cl) and second composite metrics (C2) respectively for each driver module (at each moment in time), are visualized in an ergonomic and human-interpretable manner.

[0157] According to the present invention, the first composite metric Cl and the second composite metric C2 of each respective driver module 111, 121, 131 can be timedependent metrics (i.e. that dynamically change with time). This enables monitoring the health of a plurality of lighting devices over time.

[0158] Figure 2 depicts schematically, by non-limiting example, a visual representation 33’ of the user interface device 30 of the lighting management system 100 according to the invention, wherein the visual representation 33 ’is taken at a second moment in time T2, whereas the visual representation 33 depicted in figure 1 is taken at a first moment in time Tl preceding the second moment in time T2.

[0159] Hence, referring to figure 1 and figure 2, each respective driver module 111, 121, 131 is configured to determine values of operational parameters of a set 40 of operational parameters at a first moment in time (Tl) and at a second moment in time (T2). The control system 20 is configured, for each respective driver module 111, 121, 131 of the plurality of lighting devices 11, 12, 13, to: (ii) calculate a first composite metric Cl based on the determined values of the selected at least two first operational parameters at the first moment in time Tl, and a first composite metric Cl’ based on the determined values of the selected at least two first operational parameters at the first moment in time T2. Similarly, the control system 20 is configured, for each respective driver module 111, 121, 131 of the plurality of lighting devices 11, 12, 13, to: (iv) calculate a second composite metric C2 based on the determined values of the selected at least two second operational parameters 42 at the first moment in time Tl, and a second composite metric C2’ based on the determined values of the selected at least two second operational parameters at the second moment in time T2.

[0160] Still referring to figure 2, the visual representation 33 is a time-dependent visual representation. It comprises a first visual representation 33 indicative of the first moment in time Tl. This visual representation 33 is identical to the visual representation as depicted in figure 1. The time-dependent visual representation also comprises a second visual representation 33’ indicative of the second moment in time T2. Hence, the user interface device 30 is configured to: for each respective driver module 111, 121, 131 of the plurality of lighting devices 11, 12,13, plot a first point 331, 332, 333 within the first visual representation 33 corresponding to the first composite metric Cl and the second composite metric C2 at the first moment in time Tl, and plot a second point 331’, 332’, 333’ within the second visual representation 33’ corresponding to the first composite metric Cl’ and the second composite metric C2’ at the second moment in time T2.

[0161] As mentioned before, the first composite metric Cl is related to mechanical degradation, failure, and health, while the second composite metric C2 is related to more electronic degradation, failure, and health.

[0162] Referring to figure 2, it is depicted that point 331, which represents the first lighting device 11 and the first driver module 111, is outside the region 35 delineated by the first user interface element 34 (i.e. the highlighted region 341 and the line 342) at the first moment in time Tl. It is further depicted that point 331’, which represents the first lighting device 11 and the first driver module 111, is within the region 35 delineated by the first user interface element 34 (i.e. the highlighted region 341 and the line 342) at the second moment in time T2. Thereby, point 331’ has increased both on the first composite metric axis 31 and the second composite metric axis 32 relative to point 331. Therefore, as exemplified in figure 2, the first lighting device 11 and the first driver module 111 show significant degradation, more specifically both degradation related to mechanical degradation, failure and health, as well as related to more electronic degradation, failure and health.

[0163] Similarly, referring to figure 2, it is depicted that point 332, which represents the second lighting device 12 and the second driver module 121, is outside the region 35 delineated by the first user interface element 34 (i.e. the highlighted region 341 and the line 342) at the first moment in time Tl. It is further depicted that point 332’, which represents the second lighting device 12 and the second driver module 121, is closer but still outside the region 35 delineated by the first user interface element 34 (i.e. the highlighted region 341 and the line 342) at the second moment in time T2. Thereby, point 332’ has increased substantially on the first composite metric axis 31 and lesser on the second composite metric axis 32 relative to point 332. Therefore, as exemplified in figure 2, the second lighting device 12 and the second driver module 121 show degradation, more specifically degradation related mechanical degradation, failure and health, but not (or lesser) related to more electronic degradation, failure and health. Hence, for the second lighting device 12 it may be concluded that this lighting device experiences cold start stress and vibrations, which reduce its lifetime, for example because the second lighting device may be blocked to receive incident sunlight and / or heavy traffic has increased between the measurement taken at the first moment in time Tl and the second moment in time T2.

[0164] Similarly, referring to figure 2, it is depicted that point 333, which represents the third lighting device 13 and the third driver module 131, is inside the region 35 delineated by the first user interface element 34 (i.e. the highlighted region 341 and the line 342) at the first moment in time Tl. Thus, its expected lifetime is significantly reduced compared to the other lighting devices. It is further depicted that point 333’, which represents the third lighting device 13 and the third driver module 131, is still within the region 35 delineated by the first user interface element 34 (i.e. the highlighted region 341 and the line 342) at the second moment in time T2, but that point 333’ has reduced on the second composite metric axis 32 relative to point 333. Therefore, as exemplified in figure 2, the third lighting device 13 and the third driver module 131 still show poor health, but that the expected lifetime due to electronic degradation is improved - for example because the third lighting device is receiving a more stable input current due to modifications to the electricity grid.

[0165] All in all, still referring to figure 1 and figure 2, each point entry in the visual representation 33 represents the health status of one specific LED driver module 111, 121, 131, and altogether the resulting cloud of points represents the health of the plurality of lighting devices 11, 12, 13 on fleet level. Since the points 331, 332, 333, & 331’, 332’, 333’ are rendered relative to each other in the same visual representation 33, the resulting cloud of points 331, 332, 333 & 331’, 332’, 333’ provides a context for each specific LED driver module 111, 121, 131 and how its health relates to the fleet (or rest of population). It may for example be easy to detect an outlier - e.g. depicted in figure 1 as point referenced with numeral 333 - in the cloud of points, which may be indicative of the health development of a particular LED driver module 131 not behaving conform the health development of the remaining LED driver modules of the fleet (or rest of population).

[0166] This invention is particularly advantageous for maintenance experts viewing the same visual representation 33 over time, and which can track each point (i.e. representing the health of the driver module) to identify anomalies in de dynamic development of the points 331, 332, 333 & 331’, 332’, 333’ plotted within the visual representation 33.

[0167] Hence, the lighting management system 100 according to the present invention, and the user interface device 30 thereof rendering the visual representation 33, are a beneficial technical tool that facilitates the health monitoring and reliability monitoring of a plurality of LED based lighting devices 11, 12, 13. The visual representation 33 may thus represent a “health fingerprint” of the plurality of lighting devices 11, 12, 13, and a “one glance view” of the progression of the LED driver module health at population or fleet level of the lighting devices 11, 12, 13.

[0168] Hence, the user interface device 30 renders a (single) visual representation 33 reflecting the health of a plurality of lighting devices 11, 12, 13 on fleet level, wherein multidimensional hyper data of the LED driver modules 111, 121, 131 is purposefully transformed (by selecting the appropriate composite features) into points 331, 332, 333 & 331’, 332’, 333’ in the visual representation, wherein each point 331, 332, 333 & 331’, 332’, 333’ represents a respective driver module 111, 121, 131 of the plurality oflighting devices 11, 12, 13.

[0169] All in all, the present invention provides a lighting management system 100 wherein the maximum amount of information (of operational metrics) related to a LED driver module 111, 121, 131 is persevered, while enabling a dynamic and human-interpretable visualization of said information. Therefore, the lighting management system 100 according to the present invention satisfies a need in the field of health monitoring of lighting systems.

[0170] Figure 3 depicts schematically, by non-limiting example, a lighting management system 300 according to the invention. The lighting management system 300 comprises a plurality of lighting devices 50, a control system 60, and a user interface device 70.

[0171] Namely, to facilitate explaining the present invention, figure 3 depicts a lighting management system 300 comprising a first lighting device 51 according to the invention and a same second lighting device 52 according to the invention. Each lighting device 51, 52 comprises a respective driver module 511, 521. Hence, the first lighting device 51 comprises a first driver module 511, and the second lighting device 52 comprises a second driver module 521.

[0172] Said plurality oflighting devices 10 may be luminaires or fixtures, such as a fleet of street lighting fixtures. Here, still referring to the embodiment depicted in figure 1, the lighting devices are streetlights installed in a street lighting project in Shanghai, China; where a humid subtropical climate is present, with cold winters and hot and humid summers with frequent thunderstrikes and tropical storms. Such harsh conditions may affect the health and predicted lifetime of the plurality of lighting devices.

[0173] The lighting management system 300 is similar to the lighting management system of the embodiment depicted in figure 1, but instead of the control system being remote from the plurality lighting devices, the lighting management system 300 presently depicted in figure 3 is characterized by a distributed control system that performs (at least partly) local processing.

[0174] Thus, referring to figure 3, the control system 60 comprises a plurality of local controllers 61, 62. Each local controller 61, 62 is associated with a respective lighting device 51, 52 of the plurality oflighting devices 50 and their driver modules 511, 521. To be more specific, in the present embodiment, the first lighting device 51 comprises a first local controller 61 of the control system 60, and the second lighting device 52 comprises a second local controller 62 of the control system 60. In the present embodiment, by non-limiting example, the first local controller 61 is housed within a housing of the first lighting device 51 and in communication with the first driver module 511, and the second local controller 62 is housed within a housing of the second lighting device 52 and in communication with the second driver module 521.

[0175] However, a local controller according to the invention may alternatively be mounted onto a housing of the corresponding lighting device. For example, a local controller may be connected to the respective lighting device and thereby to the driver module thereof via a Zhaga or NEMA interface. Hence, a local controller may be an outdoor lighting controller (OLC). Yet alternatively, a local controller according to the invention may be housed within the driver module. Hence, the driver module may comprise the local controller associated therewith.

[0176] Still referring to figure 3, each respective driver module 511, 521 is configured to obtain (e.g. collect, retrieve, or receive) telemetry data on a set of operational parameters. In other words, each of said driver module 511, 521 is configured to determine (e.g. measure) values of operational parameters of a set 80 of operational parameters. The respective driver module may also be configured to calculate said operational parameters based on the various telemetry data obtained, for example. Each driver module may comprise a processor suitable for such calculations.

[0177] Moreover, for example, not depicted, each driver module may comprise internal sensing means for sensing at least part of the set of operational parameters, and / or be in communication with external sensing means, for sensing at least part of the set of operational parameters and obtain (i.e. receive or retrieve) said least part of the set of operational parameters from said external sensing means. Said external sensing means may be part of the respective lighting device.

[0178] Each driver module 511, 521 is also configured to convey the determined values to the control system 60, more specifically to their respective local controller. Hence, the first driver module 511 conveys the determined values to the first local controller 61, and the second driver module 521 conveys the determined values to the second local controller 62.

[0179] Still referring to figure 3, the set 80 of operational parameters comprises at least three operational parameters. To facilitate explaining the invention, the set 80 of operational parameters comprises five operational parameters. Said operational parameters may be shortly phrased as parameters.

[0180] Namely, a first parameter (Fl) being driver module over temperature, a second parameter (F2) being water ingress level (or humidity level), a third parameter (F3) being ambient temperature, a fourth parameter (F4) being driver module lightning surge level, a fifth parameter (F5) being power level.

[0181] Considering the first parameter (Fl), driver module over temperature, this operational parameter may be calculated by the driver module based on obtained telemetry data inputs obtained by the (LED) driver module. As mentioned, it is well known in the art that the predicted lifetime of a lighting device is typically halved with every ten-degree Celsius increase in temperature of the driver module, i.e. relative to a nominal driver case temperature for normal operation. Operating at such higher temperatures may thus limit lifetime. The nominal driver case temperature may e.g. be 80 degrees Celsius.

[0182] The lifetime of the driver module can be expressed by the following equation:

[0183] TREF-TC

[0184] L = L0 x 2 io

[0185] Thereby: L is the lifetime. TREF is the (reference) case temperature of the driver module to achieve the predicted lifetime. For example, 80 degrees Celsius. Tc is the measured case temperature of the driver module, e.g. obtained from the driver module telemetry data. L0 is the base (predicted) lifetime, for example 50k hours (when operated with case temperatures corresponding to TREF).

[0186] This may be exemplified by tests wherein a LED driver module, that is designed for operating 50k hours at case temperature of 80 degrees Celsius, appeared to survive only 500 hours at a case temperature of 100 degrees Celsius, which is only and merely 20 degrees above specification. On the other hand, the health of a driver module (or: driver) improves significantly when operated at lower case temperatures, for example, the predicted lifetime of said LED driver module, that is designed for operating 50k hours at case temperature of 80 degrees Celsius, doubles with every 10 degrees Celsius decrease from the case temperature of 80 degrees Celsius for which it is designed.

[0187] Building further on this, the parameter being driver module over temperature (i.e. a feature indicative of the temperature-induced driver-health degradation) can be expressed by the following equation: 10 x tTREF~TC

[0188] It = X 2 K

[0189] L0

[0190] Thereby: It is the driver module over temperature (stress level). Tc is the measured case temperature of the driver module, e.g. obtained from the driver module telemetry data. The variable t is the operating time under temperature Tc. TREF is the (reference) case temperature of the driver module to achieve the predicted lifetime. For example, 80 degrees Celsius. L0 is the base (predicted) lifetime, for example 50k hours (when operated with case temperatures corresponding to TREF). K is a constant which equals the slope of the resulting lines of the model; and retrieved based on empirical data.

[0191] For example, when Tc is above TREF, the constant K may be:

[0192] 100 - 80 K ~ log2500 - log250000 “-3'0103

[0193] Or, for example, when Tc is below TREF, the constant K may be:

[0194] ZZ _ _ 60 - 80 _ _ 1 0 log2200000 - log250000

[0195] Other values of the constant K may be envisioned similarly.

[0196] Further: Water ingress into a lighting device (or luminaire) is an important mechanism for LED driver health degradation. For example, water ingress may be caused by a damaged mechanical seal, and may lead to material degradation and / or electronics failure.

[0197] Therefore, considering the second parameter (F2), water ingress level (or humidity level), this parameter may be calculated by the driver module based on obtained telemetry data inputs. For example, the driver module may obtain water ingress measurement data or humidity readings from a sensing means, such as a moisture sensor or humidity sensor. Alternatively, moisture ingress and / or humidity may be detected with radiofrequencybased sensing. Hence, the lighting devices according to the present invention may comprise radiofrequency-based sensing capabilities.

[0198] High humidity within the lighting device, and in particular the driver module, can induce electromigration effects on a driver PCB, which may lead to electrical shorts. The same applies to water ingress. This may affect health and reduce predicted lifetime of the lighting device and associated driver module. Moreover, the applicant of the present invention has recognized that water ingress leads to degradation of a film capacitor' s capacitance value, which is typically present within a driver module and / or lighting device. Similarly, a transformer is also typically present within a driver module and / or lighting device. A moisture ingress event may further leads to a transformer exhibiting enhanced corona discharge, whereas the moisture present within the transformer winding induces a significant leakage current between the transformer windings, which may lead to overheating of the transformer. Such overheating may also render driver module over temperature, for example.

[0199] Considering the third parameter (F3), being ambient temperature, this parameter may be calculated by the driver module based on obtained telemetry data inputs. For example, the driver module may obtain temperature measurement data from a sensing means, such as a temperature sensor.

[0200] Similar to high humidity, also high ambient temperatures are known to degrade the insulation of electronics components, such as film capacitors and transformers. Hence, driver module over temperature may not only affect the driver electronics, but also affect the ingress protection means protecting these driver electronics from undesired ambient conditions. The same applies for extremely low ambient temperatures, which may harden seals and / or lead to brittle fracture of housing materials.

[0201] Hence, both high temperatures and water ingress (or humidity) will lead to electromigration issues on the PCB of the driver module. Certain areas, such as summertime in Shanghai China, or Miami Florida, high ambient temperatures may be combined with high moisture levels, thereby leading to an unhealthy cocktail of operational conditions leading to lighting device degradation and affecting the expected lifetime of lighting devices.

[0202] Considering the fourth parameter (F4), driver module lightning surge level, for example, this operational parameter may be calculated by the driver module based on obtained telemetry data inputs obtained by the (LED) driver module.

[0203] The parameter of lightning surge level may be expressed as a function of the surge energy that is over specification in percentages, and how many times a driver module has already been hit by a lightning surge.

[0204] Namely, a (LED) driver module may be severely damaged when exposed to a number of lightning surges with a specified first surge energy, for example 40 lighting strikes with a predetermined first surge energy, e.g. 10% above specification; but similarly severely damaged by a single lightning surge with a specified second surge energy, for example a single lighting strikes with a predetermined second surge energy (being larger than the first surge energy), e.g. 50% above specification.

[0205] Hence, the operational parameter of driver module lightning surge level (or health degradation feature related to lightning strikes / surges), can be expressed by the following equation: ls= a + b * E + c * N

[0206] Thereby: Is is the driver module lightning surge level. E is the surge energy of the lightning strike. Surge energy can for example be calculated based on the telemetry data, for example by integrating the current in the MOV (Metal Oxide Varistor), which is typically present at the input of the driver module to manage the voltage spikes caused by the lightning strike, and which current may be measured. N is the number of surges or lightning strikes. The equation further contains the constants a, b, and c. Said constants may be predefined and / or prestored in the driver module. For instance, choosing a = -0.256; b = 20, c = 0.25. Other values for the constants may be envisioned as well. Said three constants may be determined by setting boundary conditions and electronics and / or lighting experts.

[0207] Alternatively, the parameter of lightning surge level may be calculated differently by a weighted sum of (A) the integral lightning strike intensity experienced by the (LED) driver module (i.e. the magnitude and duration of all the lightning-strike-related input voltage surges measured by the driver module), and (B) how often this (LED) driver module has experienced a lightning strike event (i.e. a lightning strike event may be experienced whenever the MOV of the driver module has clamped to suppress the surge), as well as (C) the amplitude and duration of each individual lightning strike that has been experienced by the driver module, together with the temperature of (the electronics ol) said driver module just before each lightning strike has occurred and experienced by the driver module.

[0208] This latter feature (i.e. the temperature of the driver module just before the lightning strike) is included here, because the inventors of the present application have found that if a first (LED) driver module exposed a lightning strike was colder before the lightning strike compared to a second (LED) driver module experiencing an equivalent (or: similar) lightning strike, the same strength lightning strike will do less damage to the first, colder (LED) driver module compared to the second, warmer (LED) driver module. Hence, it is beneficial for the health of the lighting device, and driver module, to have experienced lightning strikes at a lower driver (module) temperature. Considering the fourth parameter (F5), power level, this parameter may be obtained by the driver module internally, as the driver module controls the power level of the luminaire. Hence, power level does not only relate to the burning hours of the lighting device and thereby the predicted lifetime, but the power level may also relate to the level damage in case of e.g. lightning incidents as indicated above. Namely, as it is found that if a first (LED) driver module exposed a lightning strike was colder before the lightning strike compared to a second (LED) driver module experiencing an equivalent (or: similar) lightning strike, the same strength lightning strike will do less damage to the first, colder (LED) driver module compared to the second, warmer (LED) driver module. Hence, it is beneficial for the health of the lighting device, and driver module, to have experienced lightning strikes at a lower driver (module) temperature. A lower driver (module) temperature may be achieved by operating a luminaire at a lower power level, e.g. 50% intensity, 10% intensity.

[0209] However, as explained above, extremely cold temperatures may induce an output current ripple, due to the degradation of the electrolytic capacitor in a LED driver. When the LED driver is also exposed to a lightning strike, the very same electrolytic capacitor cannot hold the voltage of the lightning surge. Hence, in such a situation, the capacitor will let high voltages pass through - from the mains cable, to the bus, and the rest of the driver electronics. These high voltages may result in damaged electronics components and damaged LEDs. Hence, lightning strikes at extremely low temperatures are also not beneficial for the health of a driver module and / or lighting device. Therefore, it may be clear that the health of a lighting device and associated driver module depends on a complex interaction of multiple conditions, into which the present invention provides an improved insight.

[0210] All in all, still referring to figure 3, the respective driver module 511, 521 is configured to determine - for example measure or calculate - values of a set 80 of said operational parameters Fl, F2, F3, F4, F5. Each respective driver module 511, 521 is configured to convey - for example transmit, release, make available or provide - said determined values to the local controller 61, 62 associated therewith. Thus, the control system 60 and each respective local controller 61, 62 obtains (receive or retrieve) said determined values.

[0211] Each local controller 61, 62 is thereby configured, for said respective driver module 511, 521 associated therewith, to perform the steps (i), (ii), (iii), and (iv) below.

[0212] Namely, each respective local controller 61, 62 is configured to (i) select at least two first operational parameters 81 from the set 80 of operational parameters. Here, the local controller 61, 62 selects the first operational parameter Fl, the second operational parameter F2 and the third operational parameter F3 as the at least two first operational parameters 81. In this case the number of parameters in the first composite metric is three. The local controller 61, 62 is then configured, i.e. for said respective driver module 511, 521, to (ii) calculate a first composite metric Cl based on the determined values of the selected at least two first operational parameters 81. Namely, here, the local controller 61, 62 calculates said first composite metric Cl based on the determined values of the selected (Fl) driver module over temperature, (F2) water ingress level (or humidity level), and (F3) ambient temperature.

[0213] Similarly, the local controller 61, 62 is configured to (iii) select at least two second operational parameters 82 from the set 80 of operational parameters. Here, the local controller 61, 62 selects the fourth operational parameter F4 and the fifth operational parameter F5 as the at least two second operational parameters 82. In this case the number of parameters in the second composite metric is two. The local controller 61, 62 is then configured to (iv) calculate a second composite metric C2 based on the determined values of the selected at least two second operational parameters 82. Namely, here, the local controller 61, 62 calculates said second composite metric C2 based on the determined values of the selected (F4) driver module lightning surge level and (F5) power level.

[0214] Thereby, the at least two second operational parameters 82 are different from the at least two first operational parameters 81, thereby making the first composite metric Cl and the second composite metric C2 different from each other. Here, the first composite metric Cl deals more with ingress related degradation, failure, and health, while the second composite metric C2 deals more with lightning strike related degradation, failure and health. Therefore, as the second composite feature C2 contains as little information that is already contained in the first composite feature Cl, the at least two second operational parameters are substantially orthogonal to the at least two first operational parameters, which - in the present example - beneficially enables a maximum amount of information being captured by the first composite feature Cl and the remaining maximum amount of information orthogonal thereto in the second composite feature C2.

[0215] Still referring to the embodiment depicted in figure 3, more specifically, each local controller 61, 62 is configured to determine an installation location of the respective lighting device 51, 52 associated therewith. That is: the first local controller 61 determines an installation location of the first lighting device 51, the second local controller 62 determines an installation location of the second lighting device 52. Here, each lighting device 51, 52 may comprise a GPS unit to determine a GPS location and convey the GPS location to the respective local controller 61, 62 associated therewith. The respective local controller 61, 62 then determines the installation location of the associated lighting device 51, 52 based on the received or retrieved GPS location of the lighting device 51, 52. Here, the installation location is a same installation location, such as a geographic region, namely the region Shanghai. A region may be defined as an administrative region of a nation, or province, or municipality (such as a neighbourhood). Said installation location may alternatively be a street.

[0216] The local controller may also determine the installation location of the respective lighting device via alternative means, such as receiving a user input, or the installation location may be prestored in the lighting device, the driver module, or the local controller itself.

[0217] Furthermore, still referring to the embodiment depicted in figure 3, each respective local controller 61, 62 is configured to select the at least two first operational parameters 81 from the set 80 of operational parameters and the at least two second operational parameters 82 from the set 80 of operational parameters based on said determined installation location - Shanghai, China.

[0218] Such an embodiment is advantageous, as the same lighting device and / or driver module may be produced, but it may alternatively configure its behaviour (of health monitoring as described for the lighting management system according to the present invention) to its actual installation location.

[0219] Namely, the same at least two first operational parameters and at least two second operational parameters may be selected for installation location Miami, Florida; because Miami, Florida may have a similar humid subtropical climate. However, if the local controller determines an installation location associated with a different climate, the at least two first operational parameters and / or at least two second operational parameters may be selected differently.

[0220] For example, Phoenix, Arizona has a dry desert climate, which may require the at least two first operational parameter to be selected differently, since moisture related degradation does not have a dominant affect on the health of the lighting device in Phoenix, Arizona. Hence, instead of constituting the first composite metric by the operational parameters of (Fl) driver module over temperature, (F2) water ingress level and (F3) ambient temperature as done for Shanghai or Miami, the first composite metric for the installation location Phoenix, Arizona may be selected as (Al) driver module over temperature, (A2) ambient temperature, (A3) power level. The first composite metric for Phoenix, Arizona is thus more related to electrical degradation due to high temperatures. Since lightning strikes are also less common in Arizona, instead of constituting the second composite metric by the operational parameters of (F4) driver module lightning surge level and (F5) power level as done for Shanghai or Miami, the second composite metric for the installation location Phoenix, Arizona may be selected as (A4) driver module input over voltage stress level and (A5) driver module input under voltage stress level. The first composite metric for Phoenix, Arizona is thus more related to electrical degradation due to electrical grid behaviour and loading.

[0221] The selection of operational parameters and the determining of composite features may be envisioned similarly for other locations in the world.

[0222] In alternative embodiments, said selection of operational parameters and associated determination of composite features may be fixed, such as permanently fixed, i.e. for each respective installation location.

[0223] In alternative embodiments, the at least two first operational parameters and / or the at least two second operational parameters are preselected (by the respective local controller). In alternative embodiments, the local controller comprises a physics informed Artificial Intelligence (Al) algorithm configured to select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters. In alternative embodiments, the local controller may receive a user input signal indicative of the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters; and select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters based on said user input signal. In alternative embodiments, the local controller may determine a common feature of the plurality of lighting devices and select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters based on said determined common feature of the plurality of lighting devices. Said common feature may at least be one of: a nominal input voltage of the plurality of lighting devices, a type of the plurality of lighting devices, a driver module type of the plurality of lighting devices, an average age of the plurality of lighting devices.

[0224] All in all, still referring to the embodiment depicted in figure 3, the lighting management system 300 according to the present invention advantageously creates a first composite metric Cl and a second composite metric C2 respectively from differently selected at least two operational parameters 81, 82. This condenses the obtained determined values, hence condenses the information pertaining to the health of each driver module 51, 52.

[0225] Each local controller that has determined the first composite metric Cl and the second composite metric C2, for its respective driver module, is further configured to convey a signal 68, 69 indicative of the first composite metric Cl and the second composite metric C2 to the user interface device 70.

[0226] Here, said signal 68, 69 is communicated wirelessly. Each lighting device may therefore comprise a communication unit (not depicted) to communicate said signal to the user interface device. Said communication unit may be in communication with the local controller and / or part of the local controller. Alternatively, said communication may be via a wired connection.

[0227] Here, the user interface device 70 is depicted as a laptop, but may be any other user interface device suitable for conveying the first composite metric and the second composite metric to the user. Figure 3 depicts, by non-limiting example, that said laptop has software related to the Signify Interact City platform to monitor a street lighting project in Shanghai, China.

[0228] The user interface device 70 obtains each of the signals 68, 69 indicative of the first composite metric Cl and the second composite metric C2 from each respective local controller 61, 62. The user interface device 70 subsequently renders a visual representation 73. Here, the visual representation 73 is a scatter plot. The scatter plot may preferably be two dimensional. The visual representation 73 - i.e. the scatter plot - comprises a first composite metric axis and a second composite metric axis. The first composite metric axis is the X-axis of the scatter plot, with the range representing values which the first composite features Cl of each respective driver module may take. The second composite metric axis is the Y-axis of the scatter plot, with the range representing values which the second composite features C2 of each respective driver module may take.

[0229] Still referring to figure 3, the user interface device 70 is configured, for each respective driver module 511, 521 of the plurality of lighting devices 51, 52 to plot a respective point 731, 732 within the visual representation 73 corresponding to the first composite metric Cl and the second composite metric C2 of the respective driver module 511, 512.

[0230] Figure 3 depicts a first point 731 in the scatter plot 73 corresponding to the first composite metric Cl and the second composite metric C2 of the first lighting device 51 and associated driver module 511 as a four-point star. Figure 3 also depicts a second point 732 in the scatter plot 73 corresponding to the first composite metric Cl and the second composite metric C2 of the second lighting device 52 and associated driver module 521 as a four-point star. However, as a streetlighting project has typically dozens, perhaps hundreds, of lighting devices installed, especially for a city like Shanghai, figure 3 also depicts mutatis mutandis the points 733 of multiple other lighting devices in the same streetlighting project as dots in the scatter plot 73.

[0231] Moreover, albeit optionally, as depicted in the present embodiment, the user interface device 70 is configured to plot a first user interface element 74 in the visual representation 74. Hence, the visual representation 74 comprises a first user interface element 74. The first user interface element 74 is configured to delineate a region indicative of driver module risk or failure. Here, first user interface element is a line within the visual representation but may alternatively be a highlighted region or contour within the visual representation. Said highlight may be a coloured highlight.

[0232] Hence, the user interface device 70 advantageously renders a visual representation 73 having a first composite metric axis and a second composite metric axis, and for each respective driver module 511, 521 of the plurality of lighting devices 51, 52 plots a point 731, 732 within the visual representation 73 corresponding to the first composite metric Cl and the second composite metric C2. This ensures that the determined values, which are condensed in the first (Cl) and second composite metrics (C2) respectively for each driver module (at each moment in time), are visualized in an ergonomic and human- interpretable manner.

[0233] Figure 4 depicts schematically, by non-limiting example, an embodiment of a lighting management system 400 according to the invention. The lighting management system 400 comprises a plurality of (same) lighting devices 410, a control system 420, and a user interface device 430. The control system 420 comprises a central controller 421 and a plurality of local controllers 412.

[0234] Each of the plurality of lighting devices comprises a driver module 411 and a local controller 412 of said plurality of local controllers. Each lighting device 410 will therefore have a driver module 411 and a local controller 412 associated therewith. Here, said local controller 412 is depicted inside the lighting device 410, but separate from the driver module 411, while alternatively the local controller may also be part of the driver module. The driver module 411 is configured to obtain telemetry data related to the lighting device and / or driver module. Thereby, each driver module 411 is configured to determine values of operational parameters of a set of operational parameters. The driver module 411 is further configured to convey the determined values to the local controller 412.

[0235] Each respective local controller 412 is configured, for the respective driver module 411 associated therewith, (i) select at least two first operational parameters from the set of operational parameters, and (ii) calculate a first composite metric (Cl) based on the determined values of the selected at least two first operational parameters.

[0236] Each respective local controller 412 is also configured, for the respective driver module 411 associated therewith, to (iii) select at least two second operational parameters from the set of operational parameters, wherein the at least two second operational parameters are different from the at least two first operational parameters, and (iv) calculate a second composite metric (C2) based on the determined values of the selected at least two second operational parameters.

[0237] Said set of operational parameters, said selection of the at least two first operational parameters, and said selection of the at least two second operational parameters of the embodiment depicted in figure 4 may be similar to the set of operational parameters, the selection of the at least two first operational parameters, and the selection of the at least two second operational parameters of the embodiments depicted in figure 1 or figure 3. Other examples may be envisioned similarly, for example with the operational parameters mentioned in the present application.

[0238] Still referring to figure 4, the central controller 421 is in communication with the plurality of local controllers 412. Here, said communication is wirelessly, but may alternatively be via a wired connection. The lighting device 410 may therefore also comprise, not depicted, a communication unit for communicating with the central controller. The central controller 421 is configured to obtain, for each respective driver module 411 of the plurality of lighting devices 410, the first composite metric (Cl) and the second composite metric (C2) from the respective local controller 412.

[0239] Here, in the present embodiment, the central controller polls each respective lighting device 410, more specifically each respective local controller 412, to obtain the first composite metric (Cl) and the second composite metric (C2) as determined by the respective local controller 412 for the driver module 411 associated therewith. Hence, the centra controller (actively) retrieves said first composite metric (Cl) and said second composite metric (C2) from each respective local controller 412. Alternatively, each respective local controller may transmit the first composite metric and the second composite metric to the central controller. Here, said polling is done periodically. The period of said polling may be adapted to optimize for communication cost. For example, said polling may be done at a higher frequency at the end-of-life of a plurality of lighting devices, e.g. after 25000 hours of operation. Thus, the central controller 421 polls each local controller 412 of the plurality of lighting devices 410 and obtains (or retrieves) said first composite metric (Cl) and the second composite metric (C2).

[0240] However, albeit optionally, each local controller may be configured to set a flag feature if a value of said first composite metric (Cl) and / or a value of said second composite metric (C2) exceeds a predetermined flag feature threshold. The central controller then polls each local controller of the plurality of lighting devices and only obtains (or retrieves) said first composite metric (Cl) and the second composite metric (C2) from the local controllers that have set the flag feature.

[0241] In an alternative embodiment, not depicted, each local controller is configured to transmit said first composite metric (Cl) and the second composite metric (C2) to the central controller based on a value of said first composite metric (Cl) and / or a value of said second composite metric (C2). For example, only the first composite metric exceeding a first value threshold and / or the second composite metric with a value exceeding a second value threshold are transmitted, such that only relevant composite metrics may be considered for rendering in the visual representation. In such embodiments, not depicted, wherein the local controller transmits the composite metrics, the local controller may periodically convey (e.g. transmit) the signal indicative of the first composite metric (Cl) and the second composite metric (C2) at a first frequency, wherein the local controller is configured to determine (or: set) the first frequency based on a value (or, alternatively: a history of values) of the first composite metric (Cl) and / or the second composite metric (C2). For example, in an embodiment, the local controller is configured to transmit the signal indicative of the first composite metric (Cl) and the second composite metric (C2) at a first frequency if a value of said first composite metric and / or said second composite metric is within a predetermined first threshold limit (e.g. exceeds a predetermined first threshold value, or is below a predetermined first threshold value), and at a second frequency if a value of said first composite metric and / or said second composite metric is within a predetermined second threshold limit (e.g. exceeds a predetermined second threshold value, or is below a predetermined second threshold value). For example, the local controller may determine a value of total number of burning hours of the lighting device, and wherein the local controller may be periodically convey (e.g. transmit) the signal indicative of the first composite metric (Cl) and the second composite metric (C2) at a first frequency if said value is below a predetermine threshold limit (for example 25000 burning hours) and at a second frequency if said value is above a predetermined threshold limit (for example 25000 burning hours).

[0242] All in all, still referring to figure 4, the central controller 421 obtains the first composite metric Cl and the second composite metric C2 respectively from differently selected at least two operational parameters. This condenses the obtained determined values, hence condenses the information pertaining to the health of each driver module 411.

[0243] The central controller further conveys a signal 422 indicative of the first composite metric Cl and the second composite metric C2, for each local controller it has obtained said composite metrics from, to the user interface device 430. The user interface device may for example be a smartphone.

[0244] The user interface device 430 obtains the signal 422 indicative of the first composite metric Cl and the second composite metric C2 from the central controller. The user interface device 430 subsequently renders a visual representation 433. Here, the visual representation 433 is a scatter plot. The scatter plot may preferably be two dimensional. The visual representation - i.e. the scatter plot - comprises a first composite metric axis 431 and a second composite metric axis 432.

[0245] Still referring to figure 4, the user interface device 430 is configured, for each respective driver module 410 of the plurality of lighting devices 410, to plot a point within the visual representation 433 corresponding to the first composite metric Cl and the second composite metric C2 of the respective driver module 411. Hence, the visual representation renders a point cloud 434.

[0246] The visual representation 433 further comprises, albeit optionally, as depicted in the present embodiment, a first user interface element 435. Hence, the user interface device 430 is configured to plot the first user interface element 435 in the visual representation 433. The first user interface element 435 is configured to delineate a region indicative of driver module risk or failure. Here, the first user interface element is a contour 435 within the visual representation 433 but may alternatively be a highlighted region or line within the visual representation.

[0247] Moreover, according to the present invention, as mentioned before, the first composite metric Cl and the second composite metric C2 of each respective driver module can be time-dependent metrics (i.e. that dynamically change with time). This enables monitoring the health of a plurality of lighting devices over time. All in all, still referring to figure 4, each point of the resulting point cloud 434 in the visual representation 433 represents the health status of one specific LED driver module 411 and corresponding lighting device 410, and altogether the resulting cloud of points represents the health of the plurality of lighting devices 410 on fleet level. It may for example be easy to detect an outlier in the cloud of points, which may be indicative of the health development of a particular LED driver module not behaving conform the health development of the remaining LED driver modules of the fleet (or rest of population).

[0248] This invention is particularly advantageous for maintenance experts viewing the same visual representation 433 over time, and which can track each point (i.e. representing the health of a driver module) to identify anomalies in de dynamic development of the points plotted within the visual representation 433.

[0249] Hence, the lighting management system 300 according to the present invention, and the user interface device 430 thereof rendering the visual representation 433, are a beneficial technical tool that facilitates the health monitoring and reliability monitoring of a plurality of LED based lighting devices.

[0250] All in all, the present invention provides a lighting management system 400, for example with local processing and purposeful polling of data, wherein the maximum amount of information (of operational metrics) related to a LED driver module is persevered, while enabling a dynamic and human-interpretable visualization of said information, and optimization of communication cost. Therefore, the lighting management system 300 according to the present invention satisfies a need in the field of health monitoring of lighting systems.

[0251] Figure 5 depicts schematically, by non-limiting example, a method 500 of light management of a plurality of lighting devices, wherein each lighting device of the plurality of lighting devices comprises a respective driver module, according to the invention. The method 500 comprises a step 501 of: each respective driver module according to the invention determining values of operational parameters of a set of operational parameters, and conveying the determined values to the control system. The method 500 comprises a step

[0252] 502 of a control system according to the invention obtaining the determined values from each respective driver module of the plurality of lighting devices. The method comprises a step

[0253] 503 of the control system, for each respective driver module of the plurality of lighting devices, performing the sub-steps 5031 of selecting at least two first operational parameters from the set of operational parameters, and step 5032 of calculating a first composite metric (Cl) based on the determined values of the selected at least two first operational parameters; and step 5033 of selecting at least two second operational parameters from the set of operational parameters, wherein the at least two second operational parameters are different from the at least two first operational parameters, and step 5034 of calculating a second composite metric (C2) based on the determined values of the selected at least two second operational parameters. The method 500 further comprises the step 504 of a user interface device according to the invention obtaining a signal indicative of the first composite metric (Cl) and the second composite metric (C2); and a step 505 of the user interface device rendering a visual representation having a first composite metric axis and a second composite metric axis, and a step 506 of the user interface device, for each respective driver module of the plurality of lighting devices, plotting a point within the visual representation corresponding to the first composite metric and the second composite metric.

Claims

CLAIMS:

1. A lighting management system (100) comprising:- a plurality of lighting devices (10);- a control system (20);- a user interface device (30); wherein each lighting device (11, 12, 13) of the plurality of lighting devices (10) comprises a respective driver module (111, 121, 131) configured to determine values of operational parameters of a set (40) of operational parameters, and to convey the determined values to the control system (20); wherein the control system (20) is configured, for each respective driver module (111, 121, 131) ofthe plurality of lighting devices (11, 12, 13), to:(i) select at least two first operational parameters (41) from the set of operational parameters (40), and (ii) calculate a first composite metric (Cl) based on the determined values of the selected at least two first operational parameters (41);(iii) select at least two second operational parameters (42) from the set (40) of operational parameters, wherein the at least two second operational parameters (42) are different from the at least two first operational parameters (41), and (iv) calculate a second composite metric (C2) based on the determined values of the selected at least two second operational parameters (42); wherein the user interface device (30) is configured to:- obtain a signal (29) indicative of the first composite metric (Cl) and the second composite metric (C2) from the control system (20);- render a visual representation (33) having a first composite metric axis (31) and a second composite metric axis (32), and- for each respective driver module (111, 121, 131) of the plurality of lighting devices (11, 12, 13) plot a point (331, 332, 333) within the visual representation (33) corresponding to the first composite metric and the second composite metric.

2. The lighting management system according to claim 1, wherein the control system (20) is a central controller configured to obtain the determined values from each respective driver module (111, 121, 131) of the plurality of lighting devices (11, 12, 13), and wherein the central controller is configured to (v) convey a signal indicative of the first composite metric (Cl) and the second composite metric (C2) to the user interface device (30).

3. The lighting management system according to claim 1, wherein the control system comprises a plurality of local controllers; wherein each local controller of the plurality of local controllers is associated with a respective lighting device of the plurality of lighting devices; wherein each local controller is configured to obtain the determined values from the driver module of the respective lighting device associated therewith; wherein each local controller is configured, for said respective driver module associated therewith, to:(i) select the at least two first operational parameters from the set of operational parameters, and (ii) calculate the first composite metric (Cl) based on the determined values of the selected at least two first operational parameters;(iii) select the at least two second operational parameters from the set of operational parameters, wherein the at least two second operational parameters (42) are different from the at least two first operational parameters, and (iv) calculate the second composite metric (C2) based on the determined values of the selected at least two second operational parameters.

4. The lighting management system according to claim 3, wherein the control system comprises a central controller in communication with the plurality of local controllers; wherein the central controller is configured, for each respective driver module of the plurality of lighting devices, to obtain the first composite metric (Cl) and the second composite metric (C2) from the plurality of local controllers.

5. The lighting management system according to any one of the preceding claims, wherein the at least two first operational parameters and / or the at least two second operational parameters are preselected.

6. The lighting management system according to any one of the preceding claims1-4, wherein the control system is configured to determine an installation location for the plurality of lighting devices, and wherein the control system is configured to select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters based on said determined installation location.7 The lighting management system according to any one of the preceding claims1-4, wherein the control system is configured to: receive a user input signal indicative of the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters; wherein the control system is configured to select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters based on said user input signal.

8. The lighting management system according to any one of the preceding claims 1-4, wherein the control system is configured to determine a common feature of the plurality of lighting devices, and wherein the control system is configured to select the at least two first operational parameters from the set of operational parameters and / or the at least two second operational parameters from the set of operational parameters based on said determined common feature of the plurality of lighting devices.

9. The lighting management system according to claim 2, wherein the plurality of lighting devices comprises a master lighting device, wherein the central controller is arranged in the master lighting device.

10. The lighting management system according to any one of the preceding claims, wherein each respective driver module (111, 121, 131) is configured to determine values of operational parameters of a set of operational parameters at a first moment in time (Tl) and at a second moment in time (T2);wherein the control system (20) is configured, for each respective driver module (111, 121, 131) ofthe plurality of lighting devices (11, 12, 13), to:(ii) calculate the first composite metric (Cl) based on the determined values of the selected at least two first operational parameters (41) at the first moment in time (Tl) and at the second moment in time (T2); and(iv) calculate the second composite metric (C2) based on the determined values of the selected at least two second operational parameters (42) at the first moment in time (Tl) and at the second moment in time (T2); wherein the visual representation (33) is a time-dependent visual representation comprising a first visual representation (33) indicative of the first moment in time (Tl) and a second visual representation (33’) indicative of the second moment in time (T2); wherein the user interface device (30) is configured to:- for each respective driver module (111, 121, 131) of the plurality of lighting devices (11, 12, 13) plot a first point (331) within the first visual representation (33) corresponding to the first composite metric and the second composite metric at the first moment in time (Tl), and plot a second point (331’) within the second visual representation (33’) corresponding to the first composite metric and the second composite metric at the second moment in time (T2).

11. The lighting management system according to any one of the preceding claims, wherein the set of operational parameters comprises at least three of:(i) driver module input over voltage stress level;(ii) driver module input under voltage stress level;(iii) driver module lightning surge level;(iv) driver module over temperature;(v) driver module cold start stress;(vi) vibration level;(vii) lighting surge frequency / lighting strike frequency;(viii) bus voltage;(ix) ambient temperature level;(x) water ingress level;(xi) grid voltage transient;(xii) power level;(xiii) operational state of the LED light source associated with the driver module.

12. The lighting management system according to any one of the preceding claims, wherein the control system is configured to select cold start stress level and vibration level from the set of operational parameters, and configured to calculate the first composite metric (Cl) based on the determined values of the selected cold start stress level and the vibration level; wherein the control system is configured to select lighting strike frequency and driver module input under voltage stress level from the set of operational parameters, and configured to calculate the second composite metric (C2) based on the determined values of the selected lighting strike frequency and driver module input under voltage stress level.

13. The lighting management system according to any one of the preceding claims Ml, wherein the control system is configured to select ambient temperature and power level from the set of operational parameters, and configured to calculate the first composite metric (Cl) based on the determined values of the selected ambient temperature and the power level; wherein the control system is configured to select driver module input over voltage stress level and driver module input under voltage stress level from the set of operational parameters, and configured to calculate the second composite metric (C2) based on the determined values of the selected driver module input over voltage stress level and driver module input under voltage stress level.

14. A method of light management of a plurality of lighting devices, wherein each lighting device of the plurality of lighting devices comprises a respective driver module, wherein the method comprises:- each respective driver module determining values of operational parameters of a set of operational parameters, and conveying the determined values to the control system;- a control system obtaining the determined values from each respective driver module of the plurality of lighting devices;- the control system, for each respective driver module of the plurality of lighting devices, (i) selecting at least two first operational parameters from the set of operational parameters, and (ii) calculating a first composite metric (Cl) based on the determined values of the selected at least two first operational parameters;- the control system, for each respective driver module of the plurality of lighting devices, (iii) selecting at least two second operational parameters from the set of operational parameters, wherein the at least two second operational parameters are different from the at least two first operational parameters, and (iv) calculating a second composite metric (C2) based on the determined values of the selected at least two second operational parameters;- a user interface device obtaining a signal indicative of the first composite metric (Cl) and the second composite metric (C2);- the user interface device rendering a visual representation having a first composite metric axis and a second composite metric axis, and- the user interface device, for each respective driver module of the plurality of lighting devices, plot a point within the visual representation corresponding to the first composite metric and the second composite metric.

15. A lighting device arranged for operating within a lighting management system according to claim 1, the lighting device comprising a local controller and a driver module, wherein the driver module is configured to determine values of operational parameters of a set of operational parameters, and to convey the determined values to the local controller; wherein the local controller is configured to (i) select at least two first operational parameters from the set of operational parameters, and (ii) calculate a first composite metric (Cl) based on the determined values of the selected at least two first operational parameters; (iii) select at least two second operational parameters from the set of operational parameters, wherein the at least two second operational parameters are different from the at least two first operational parameters, and (iv) calculate a second composite metric (C2) based on the determined values of the selected at least two second operational parameters; wherein the local controller is configured to convey a signal indicative of the first composite metric (Cl) and the second composite metric (C2)

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