Synchronizing active road studs to change operation at the same time or in sequential order

Abstract

Active road studs along a roadway are controlled to make synchronized operation changes. The active road studs making synchronized operation changes include the active road studs making the same operation change in synchronization with one another, such as at the same time (e.g., simultaneously) or in a sequential order (i.e., sequentially). In operation, a base station transmits a command to the active road studs, the command including information indicative of the operation change to make and when the active road studs are to make the operation change. The sequential order may be based on geographic locations of the active road studs along the roadway. The operation change that each active road stud may make includes turning on a light-emitting diode (LED) of the active road stud, turning off the LED of the active road stud, and changing the color of light emitted by the active road stud.

Description

SYNCHRONIZING ACTIVE ROAD STUDS TO CHANGE OPERATION AT THE SAME TIME OR IN SEQUENTIAL ORDERTECHNICAL FIELD

[0001] The present invention relates to controlling active road studs installed in a roadway.BACKGROUND

[0002] Road studs (e.g., pavement markers) are installed on or in roads (or “roadways”) to mark lanes and edges of the roads. Reflective road studs reflect light such as from vehicle headlights in order to be visible to vehicle drivers. Active road studs (or “road studs” or “studs”) include one or more light-emitting diodes (LEDs) to emit light in order to be visible to vehicle drivers. Vehicle drivers are to be able to visually observe installed road studs while driving on a road in order to properly follow the road including any curves and corners of the road.

[0003] Active road studs are designed to be responsive to the ambient light level to turn on at dusk to emit light and to turn off at dawn to not emit light. The active road studs may have different levels of responsiveness to ambient light. Consequently, active road studs along a section of the road may turn on / off at different times from one another, such as on the order of a few minutes. As such, the active road studs are not synchronized in turning on / off for vehicle drivers to see them turning on / off together.

[0004] Turning on and turning off of an active road stud are each a type of change made in the operation of the active road stud. Other types of operation changes for an active road stud include turning on during periods of poor visibility (e.g., in the presence of fog). In the case of an active road stud having different colored LEDs, another type of operation change includes changing the color of the light emitted from the active road stud such as to indicate information to vehicle drivers.

[0005] Conventionally, controlling active road studs from an external decision (e.g., a base station) employs wireless communication to convey to the active road studs a command indicative of an operation change that the active road studs are to make. However, in order to minimize power consumption, the wireless communication capability of the active road studs will not be active all of the time. The potential for adverse communication conditions means that it cannot be dependent on any one specific command from the base station being received immediately by all of the active road studs. Thus, an operator cannot simply simultaneously command all active road studs to make an operation change and expect that the active road studs will receive and execute the operation change in synchronization with one another (e.g., cannot expect that the active road studs will together execute the operation change at the same time).SUMMARY

[0006] An object of the present invention includes controlling active road studs to make synchronized operation changes. As used herein, the term “road studs” includes studs associated with other surfaces, e.g., off-track surfaces, footpaths, trails, and the like.

[0007] Another object of the present invention includes controlling active road studs to make the same operation change in synchronization with one another, such as at the same time (e.g., simultaneously) or in a sequential order (i.e., sequentially).

[0008] A method for use with active road studs installed along a roadway is provided. The method includes receiving, by the active road studs, a command from a base station. The command includes information indicative of an operation change that the active road studs are to make and a future time at which the active road studs are to make the operation change. The method further includes measuring time by each active road stud using a source of timing information common to the active road studs so that the active road studs have the same measure of the future time. The method further includes executing, by the active road studs, the operation change at the future time as measured by the active road studs whereby the active road studs execute the operation change synchronously.

[0009] The step of measuring time by each active road stud may include using a global navigation satellite system (GNSS) transceiver of the active road stud.

[0010] The operation change may be for each active road stud to turn on a light-emitting diode (LED) of the active road stud. In this case, the step of executing includes the active road studs turning on the LEDs at the future time as measured by the active road studs whereby the active road studs turn on the LEDs synchronously.

[0011] The operation change may be for each active road stud to turn off a light-emitting diode (LED) of the active road stud. In this case, the step of executing includes the active road studs turning off the LEDs at the future time as measured by the active road studs whereby the active road studs turn off the LEDs synchronously.

[0012] The operation change may be for each active road stud to change a color of light emitted by the active road stud. In this case, the step of executing includes the active road studs changing the color of emitted light at the future time as measured by the active road studs whereby the active road studs change the color of emitted light synchronously.

[0013] Another method for use with active road studs installed along a roadway is provided. This method includes transmitting, by each active road stud, a message to a base station. The message of each active road stud includes information indicative of a time at which the active road stud transmitted the message as measured by the active road stud. This method further includes receiving, by each active road stud, a command from the base station. The command for each active road stud includes information indicative of an operation change that the active road studs are to make and a future time at which the active road stud is to make the operation change relative to the time at which the active road stud transmitted the message as measured by the active road stud. This method further includes executing, by each active road stud, the operation change at the future time at which the active road stud is to make the operation change whereby the active road studs execute the operation change synchronously.

[0014] Another method for use with active road studs installed along a roadway is provided. This method includes arranging the active road studs in a sequential order. Thismethod further includes receiving, by the active road studs, a command from a base station. The command includes information indicative of an operation change that the active road studs are to make and future times at which the active road studs are to respectively make the operation change according to their arrangement in the sequential order. This method further includes executing, by each active road stud, the operation change at the future time at which the active road stud is make the operation change whereby the active road studs execute the operation change sequentially.

[0015] The sequential order may be based on positioning of the active road studs along the roadway.

[0016] The step of arranging the active road studs in the sequential order may include identifying one of the active road studs as being a first active road stud in the sequential order; identifying, by the first active road stud, based on a polling signal transmitted by the first active road stud, the one of the active road studs closest to the first active road stud as being a second active road stud in the sequential order; and identifying, by the second active road stud, based on a polling signal transmitted by the second active road stud, the one of the active road studs closest to the second active road stud other than the first active road stud as being a third active road stud in the sequential order.

[0017] The command may further include information indicative of a second operation change that the active road studs are to make and future times at which the active road studs are to respectively make the second operation change according to their arrangement in the sequential order. In this case, the step of executing further includes executing, by each active road stud, the second operation change at the future time at which the active road stud is make the second operation change whereby the active road studs execute the second operation change sequentially.

[0018] Further in this case, the operation change may be for each active road stud to turn on a light-emitting diode (LED) of the active road stud and the second operation change may be for each active road stud to turn off the LED of the active road stud. The step of executing may include each active road stud (i) turning on the LED of the active road stud at the future time atwhich the active road stud is to make the operation change whereby the active road studs turn on the LEDs in the sequential order and (ii) turning off the LED of the active road stud at the future time at which the active road stud is to make the second operation change whereby the active road studs turn off the LEDs sequentially.BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 illustrates a schematic diagram including (i) a view of a straightaway portion of an exemplary roadway having active road studs installed therein and a blown-up view of a part of the straightaway roadway portion and (ii) a view of a curved portion of the roadway having active road studs installed therein and a blown-up view of a part of the curved roadway portion;

[0020] FIG. 2 illustrates a block diagram of an active road stud;

[0021] FIG. 3 illustrates a block diagram of a system configured to control a set of active road studs to make synchronized operation changes;

[0022] FIG. 4A illustrates a flowchart depicting operation of the system for controlling a set of active road studs to make an operation change at the same time;

[0023] FIG. 4B illustrates a flowchart depicting alternate operation of the system for controlling a set of active road studs to make an operation change at the same time; and

[0024] FIG. 5 illustrates a flowchart depicting operation of the system for controlling a set of active road studs to make an operation change sequentially.DETAILED DESCRIPTION

[0025] Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore,specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

[0026] Referring now to FIG. 1, a schematic diagram of an exemplary roadway having active road studs 10 installed therein is shown. The schematic diagram of FIG. 1 includes a view of a straightaway portion 12 of the roadway and a blown-up view of a part of the straightaway roadway portion. The schematic diagram of FIG. 1 further includes a view of a curved portion 14 of the roadway and a blown-up view of a part of the curved roadway portion.

[0027] The roadway includes a first lane 16 and a second lane 18 having opposite directions of travel (e.g., shown via arrows in the roadway). Of course, the roadway could include any number of lanes running in the opposite or same directions of travel. The roadway is configured to have multiple vehicles traveling along the roadway in the path of travel. The vehicles may include automobiles, trucks, tractor trailers, motorcycles, motorized scooters, bicycles, and the like. Alternatively, the roadway may be in the form of a runway, holding area, and / or taxiway in an airport environment. In such a case, the roadway would be configured to have airplanes, service vehicles, and the like in paths of travel.

[0028] As shown in FIG. 1, the roadway includes active road studs 10. Each active road stud 10 can be coupled, removably coupled, or otherwise disposed in and / or along the roadway. In this exemplary roadway, a first set of active road studs 10 are positioned between lanes 16 and 18. The first set of active road studs 10 can provide a visual indication marking the boundary between lanes 16 and 18. The first set of active road studs 10 can be placed a predetermined distance apart along the direction of travel.

[0029] Further in the exemplary roadway, a second set of active road studs 10 are positioned along the outer exterior or boundary of lane 16 and a third set of active road studs 10 are positioned along the outer exterior or boundary of lane 18. The second and third sets of active road studs 10 can provide a visual indication of the edge of lanes 16 and 18, respectively.

[0030] Referring now to FIG. 2, with continual reference to FIG. 1, a block diagram of an active road stud 10 is shown. In overview, active road stud 10 is a solar-powered, wireless communicable, light emitting device.

[0031] As a light emitting device, active road stud 10 includes one or more light-emitting diodes (LEDs) 20 for emitting light. LEDs 20 may be configured to emit a constant beam of light or to flash on and off. Each LED 20 may include a monochrome diode or an RBG diode unit. For example, active road stud 10 includes two LED arrays, one LED array having one or more LEDs for emitting light in one direction of travel along the roadway and the other LED array having one or more LEDs for emitting light in the opposite direction of travel along the roadway. The LEDs of an LED array can include, for example, one or more LEDs that emit red light, one or more LEDs that emit green light, and one or more LEDs that emit blue light. Active road stud 10 may further include one or more reflectors that can be configured to mix the light being emitted by different colored LEDs to provide an emitted light color that is different from the original light being emitted by each discreet LED. Likewise, multiple colors may be included within a single LED diode in order to emit a color of light different from the multiple colors included within the single LED diode.

[0032] Being wirelessly communicable, active road stud 10 includes a wireless receiver 22 and a wireless transmitter 24. Receiver 22 is operable for receiving wireless communication signals from a base station (shown in FIG. 3) within wireless communication range of the receiver and from any other active road stud within the wireless communication range of the receiver. Transmitter 24 is operable for transmitting wireless communication signals for reception by the base station and by any other active road stud within the wireless communication range of the transmitter. The wireless communication signals may be control signals and / or information / status signals. The wireless communication signals may employ radio frequency (RF) or infra-red (IR) communications.

[0033] By being solar-powered, active road stud 10 includes a power supply 26 having a battery and a solar panel (neither shown). Electric energy from the battery is used to power the operations and components of active road stud 10. The solar panel is operable for convertingsolar energy into electric energy. The battery is operable to be recharged for storing the electric energy generated by the solar panel. The solar panel may be further operable for outputting a control signal indicative of whether it is daytime or nighttime, as well as sunny or cloudy.

[0034] Active road stud 10 further includes a controller 28. Controller 28 is operable for controlling operation of the components of active road stud 10 including LED 20, receiver 22, and transmitter 24. For example, controller 28 receives control signals of wireless communication received by receiver 22 and controls LEDs 20 and / or transmitter 24 according to the control signals. For instance, controller 28 controls LEDs 20 to turn on or off according to corresponding control signals. Likewise, controller 28 controls transmitter 24 according to corresponding control signals to transmit wireless communication.

[0035] Controller 28 includes a local clock 30 for keeping track of time. Controller 28 may be any type of computer processor such as a microprocessor. Controller 28 may have a memory unit. The memory unit may be employed to store parameters of working manners of active road stud 10, flash intervals, fancy flash styles, ordinal numbers, and colors.

[0036] Active road stud 10 may further include a global navigation satellite system (GNSS) (e.g., a global positioning system (GPS)) transceiver 32. GNSS transceiver 32 can provide an exact position for the particular active road stud 10 along the roadway.

[0037] Active road stud 10 may further include a vehicle sensor (not shown) configured to sense and determine when a vehicle passes by and / or over the active road stud. The vehicle sensor may be a magnetic sensor, an inductive loop detector, an active or passive infrared detector, or an acoustic sensor. Measurements (e.g., event data) taken by the vehicle sensor can be used to determine for example the size, position in lane, and the velocity of the vehicle passing by active road stud 10 (e.g., when the same vehicle is observed by the next active road stud in the direction of travel along the roadway, the velocity of the vehicle can be calculated based on the signal provided by each active road stud, the time between the two signals, and the known distance between the active road studs).

[0038] Active road stud 10 may further include a temperature sensor (not shown) configured to measure a temperature in the active road stud and adjacent to a top surface of the roadway. Controller 28 may be configured to account for humidity and wind chill conditions based on data received from the temperature sensor.

[0039] Active road stud 10 may further include a humidity sensor (not shown) configured to measure the ambient humidity of the environment around active road stud 10. Controller 28 may be configured to evaluate the humidity data in conjunction with the temperature data to provide a more accurate determination as to whether the roadway is likely to have or may soon have ice.

[0040] Active road stud 10 may further include a photosensor (not shown) configured to measure the amount of ambient light received into the active road stud from the surrounding environment. The photosensor can measure ambient light levels in order to determine how bright the LED light emitted by the LEDs 20 needs to be. The photosensor, either alone or in conjunction with another sensor (e.g., the temperature and / or the humidity sensor) can be configured to detect fog, smoke, heavy rain, or other environmental situations that obscure the view on the roadway.

[0041] Referring now to FIG. 3, with continual reference to FIGS. 1 and 2, a block diagram of a system 40 configured to control a set of active road studs 10 (active road stud 10a, active road stud 10b, ... active road stud lOn) to make synchronized operation changes is shown. System 40 includes a base station (access point, hub, gateway, etc.) 42. Base station 42 is positioned to be within wireless communication of the set of active road studs 10. For instance, the set of active road studs (e.g., 20 - 5,000 active road studs) are positioned in neighboring fashion along a portion of the roadway and base station 42 is located along a central part of the portion of the roadway. As such, the set of active road studs 10 shown in FIG. 3 are in wireless communication with base station 42. Base station 42 is configured to transmit and receive wireless communication with each active road stud 10. Such wireless communication includes control signals for controlling active road studs 10.

[0042] Other active road studs that are along other portions of the roadway are too far away from base station 42 and thereby are not in wireless communication with the base station. In this case, system 40 includes additional base stations for controlling these other active road studs. Each additional base station is configured to transmit and receive wireless communication with the active road studs within the communication range of that base station.

[0043] As described above, an active road stud 10 is operable to detect ambient light and turn on / off depending on the level of detected ambient light. Turn on / off an active road stud is in the context of the active road stud turning on / off the LEDs of the active road stud. As such, an active road stud is operable to turn on its LEDs 20 to emit light upon detecting the commencement of dusk and is operable to turn off its LEDs to not emit light upon detecting the commencement of dawn.

[0044] As further described above, active road studs 10 have different responsiveness to ambient light. Consequently, the set of active road studs 10 within the communication range of base station 42 may turn on / off at dusk / dawn at different times from one another. As such, for a period of time such as a few minutes at the commencement of dusk, some of the active road studs 10 may remain improperly turned off while the remaining active road studs have been properly turned on. Likewise, for a period of time such as a few minutes at the commencement of dawn, some of the active road studs 10 may remain improperly turned on while the remaining active road studs have been properly turned off. These conditions in which neighboring active road studs 10 are not synchronized in turning on / off together may appear to be disorganized and distractive to vehicle drivers.

[0045] In accordance with embodiments of the present invention, system 40 is operable to control active road studs 10 to be synchronized in turning on / off together. More generally, system 40 is operable to control active road studs 10 to make synchronized operation changes. Operation changes of an active road stud 10 include the active road stud turning on at dusk, turning off at dawn, turning on in the presence of fog, changing color of emitted light, transmitting a control or information signal, etc. The types of synchronicity include implementing the operation change of active road studs 10 at the same time (e.g.,simultaneously) or in sequential order (i.e., sequentially). In the former case, active road studs 10 turn on together at the same time, turn off together at the same time, change color of emitted light together at the same time, etc. In the latter case, active road studs 10 turn on in a sequential order (e.g., from the active road stud positioned at the beginning of the portion of the roadway, to the next neighboring active road stud, to the next neighboring active road stud, etc., to the active road stud positioned at the end of the portion of the roadway), turn off in the sequential order, change color of emitted light in the sequential order, etc.

[0046] As set forth, an advanced case is not just synchronizing the operation change of active road studs 10 to be simultaneous (i.e., done at the same time), but to be in sequence as per their order along the roadway (e.g., to give the effect of a light moving along the roadway). A challenge here is establishing the correct order of active road studs 10 along the roadway. While this could be prescribed against identification (ID) of individual active road studs before installation or manually recorded IDs after installation, both approaches are prone to error, labor intensive, and require manual intervention to update should any active road studs be changed at a later date.

[0047] Another use case for knowing the order of active road studs along the roadway is when the active road studs can sense vehicles passing and an operator of system 40 wants to combine data from multiple active road studs to measure the vehicle speed. In this case, the operator needs to know the order and spacing of the active road studs to measure the vehicle speed.

[0048] Referring now to FIG. 4A, with continual reference to FIGS. 1, 2, and 3, a flowchart 50 depicting operation of system 40 for controlling the set of active road studs 10 to make an operation change at the same time (i.e., simultaneously) is shown. The operation includes base station 42 transmitting a command for receipt by active road studs 10, as indicated in process block 52. The command includes information indicative of a type of operation change that the active road studs are to make. For instance, the operation change that the active road studs are to make is to turn on. The command further includes information indicative of a future time (e.g., 7:57:00 pm) at which the active road studs are to make the operation change. Forinstance, base station 42 transmits the command at 7:56:00 pm and the active road studs are to implement the operation change at 7:57:00 pm. Base station 42 may retransmit the command per process block 52 any number of times up until the future time.

[0049] The period between the time that base station 42 transmits the command per process block 52 and the commanded future time is larger than a predetermined minimum value. The predetermined minimum value is selected such as by base station 42 based on evaluation from the worst-case latency of the communication channel allowing for the active road studs being asleep to conserve energy, communication retries, and time to communicate with the required number of individual active road studs.

[0050] The operation further includes active road studs 10 keeping track of time, as indicated by process block 54. In this regard, each active road stud 10 has a means for that active road stud to keep track of time so that the active road stud can (wake-up and) execute the commanded operation change at the commanded time. Means of keeping track of time can be derived from GNSS transceiver 32 (e.g., a GPS receiver) of active road stud 10 or either from a radio data system (RDS) (FM radio) receiver or a mobile network receiver (2G / 3G / 4G / 5G / ...) of the active road stud to provide a reference and updates supported by local clock 30 of the active road stud. Known techniques enable local clock 30 to be made more accurate by calibrating its frequency by using the more accurate time reference received from the other source.

[0051] Following the reception by active road studs 10 of the command from base station 42, the active road studs execute the commanded operation change at the commanded time, as indicated by process block 56. For instance, in this example, each active road stud 10 turns on at 7:57:00 pm, whereby the active road studs turn on together at 7:57:00 pm.

[0052] For large installations, a single base station may be unable to communicate with all of the active road studs. Hence, the active road studs may be structured into groups, such as by geographic location, with their own base stations. Now the synchronization challenge becomes hierarchical as similar mechanisms must apply at each layer in order to maintain simultaneous changes. The worst-case latency referred to above should consider the worst-case scenario across all members of the hierarchy.

[0053] As described, the commanded future time at which active road studs 10 are to execute the commanded operation change is the same for each active road stud whereby the active road studs synchronously execute the commanded operation change at the same time (i.e., simultaneously). In a variation, the commanded future time at which active road studs 10 are to execute the commanded operation change is different for each active road stud whereby the active road studs synchronously execute the commanded operation change at different times (i.e., sequentially).

[0054] Referring now to FIG. 4B, with continual reference to FIGS. 1, 2, 3, and 4A, a flowchart 60 depicting alternate operation of system 40 for controlling the set of active road studs 10 to make an operation change at the same time (i.e., simultaneously) is shown. The alternate operation includes each active road stud 10 transmitting an initial message to base station 42, as indicated by process block 62. The initial message of each active road stud 10 includes information indicative of when the active road stud transmitted the initial message as measured by the active road stud. That is, the initial message of each active road stud 10 includes the time, according to the clock of the active road stud, that the active road stud transmitted the initial message.

[0055] As described, the “clock time” information included in the initial message of an active road stud 10 is the time which the active road stud understands as being the time that the active road stud transmitted the initial message (i.e., the time at which the active road stud transmitted the initial message according to the clock of the active road stud). The “actual time” is assumed to be the time as measured by base station 42 (i.e., the time according to the clock of the base station).

[0056] Following reception by base station 42 of the initial messages transmitted from active road studs 10, the alternate operation further includes the base station transmitting reply messages, respectively, to active road studs 10, as indicated by process block 64. The reply messages are in response to the initial messages. The reply message to each active road stud 10 includes information indicative of a type of operation change that the active road stud is to make.

[0057] The reply message to each active road stud 10 further includes information indicative of a future time (i.e., an actual time according to the clock of base station 42) at which the active road stud is to make the operation change relative to the time the active road stud transmitted the initial message as measured by the active road stud. That is, the reply message to each active road stud 10 further includes information indicative of the actual time at which the active road stud is to make the operation change relative to the clock time of the active road stud.

[0058] For instance, assume the future time at which active road studs 10 together are to make the operation change is 7:57:00 pm (i.e., the actual time according to the clock of base station 42 at which active road studs 10 together are to make the operation change is 7:57:00 pm). In this example, assuming a first active road stud 10 transmitted its initial message at 7:50:00 indicating its clock time was 7:50: 10, the information of the reply message from base station 42 for the first active road stud will indicate that the first active road stud is to execute the operation change in 7:00 minutes at the time of 7:57: 10 according to the clock time of the first active road stud. Likewise, in this example, assuming a second active road stud 10 transmitted its initial message at 7:53:00 indicating its clock time was 7:52:30, the information of the reply message from base station 42 for the second active road stud will indicate that the second active road stud is to execute the operation change in 4:00 minutes at the time of 7:56:30 according to the clock time of the second active road stud.

[0059] Following the reception by active road studs 10 of the respective reply messages from base station 42, the alternate operation further includes each active road stud executing the operation change at the future time indicated by the reply message for the active road stud, as indicated by process block 66. Consequently, in this example, active road studs 10 turn on together at the actual time of 7:57:00 pm.

[0060] As described, the alternate operation for controlling a set of active road studs 10 to make an operation change together at the same time involves each active road stud transmitting an initial message to base station 42, the base station responding to each initial message with a reply message telling the originating active road stud when to perform an action (i.e., an operation change) relative to the time at which the originating active road stud had sentthe initial message as measured by the originating active road stud. Hence, each originating active road stud never has to know or be synchronized with the actual time. The action could be when to next transmit or receive (depending on the primary direction of communication that are required) or to change in some other way (e.g., to turn on).

[0061] As described, the future time at which each active road stud 10 is to make the operation change relative to the time the active road stud transmitted the initial message as measured by the active road stud is the same for each active road stud whereby the active road studs synchronously make the operation change at the same time (i.e., simultaneously). In a variation, the future time at which each active road stud 10 is to make the operation change relative to the time the active road stud transmitted the initial message as measured by the active road stud is different for each active road stud whereby the active road studs synchronously make the operation change at different times (i.e., sequentially).

[0062] Referring now to FIG. 5, a flowchart 70 depicting operation of system 40 for controlling set of active road studs 10 to make an operation change sequentially is shown. Active road studs 10 making an operation change sequentially means that the active road studs are arranged in an order and the first active road stud in the order initially makes the operation change, followed by the second active road stud in the order making the operation change, followed by the third active road stud in the order making the operation change, etc., followed by the last active road stud in the order making the operation change.

[0063] The order may be based on geographic location of the active road studs and / or some other criteria. In the case of the order being based on geographic location of the active road studs along a roadway, the active road studs make the operation change in sequence per their order along the roadway. Consequently, when the operation change is to turn on, the active road studs turning on in sequence per their order along the roadway gives the effect of a light moving along the roadway. Of course, the routine could be more elaborate with each active road stud turning off as its neighboring active road stud is turned on. In this case, the effect would be a dotted line moving along the roadway.

[0064] Initially, the operation for controlling set of active road studs 10 to make an operation change sequentially includes a sub-operation for generating a list of active road studs 10 in a sequential order based on geographic location of the active road studs. Per the sequential order, the first active road stud is located at the start of the portion of the roadway along a direction of travel, the second active road stud is located next to the first active road stud along the direction of travel, the third active road stud is located next to the second active road stud along the direction of travel, etc., and the last active road stud is located at the end of the portion of the roadway along the direction of travel.

[0065] The sub-operation for generating a list of active road studs 10 in a sequential order includes identifying the active road stud located at the start of the portion of the roadway, as indicated by process block 72. This active road stud is the first active road stud in the sequence. For instance, the first active road stud is identified by this active road stud and base station 42 communicating GNSS information with one another, knowledge by base station 42 of the location of the start of the of the portion of the roadway, and the like.

[0066] The first active road stud stores in its memory the fact that it is the first active road stud. The first active road stud then transmits a polling signal for receipt by other active road studs within the communication range of the first active road stud, as indicated by process block 74. The first active road stud measures the distance to each other active road stud based on the polling information, as indicated by process block 76. For example, the active road stud transmits the polling signal and the active road studs transmits replies to the polling signal for the polling process using ultra-wideband (UWB) wireless communication as per technology used in tags. The first active road stud records the distance against the identification of each other active road stud and orders the list by distance. The first active road stud identifies its closest neighboring active road stud from the list as being the second active road stud in the sequence, as indicated by process block 78. The first active road stud transmits a notification message to the second active road stud informing the second active road stud that it is the second active road stud in the sequence, as indicated by process block 80. The second active road stud stores in its memory the fact that it is the second active road stud.

[0067] The second active road stud then repeats these processes, as indicated by process blocks 82. The second active road stud excludes the first active road stud from consideration of its closest neighboring active road stud when performing these processes. Each active road stud in turn repeats these processes as they are told their sequence number by the preceding active road stud, passing on a list of the active road studs already in the sequence. The sub-operation is terminated when the last active road stud in the sequence is identified, as indicated by process block 84.

[0068] In this way, the sub-operation, composed of process blocks 72 through 84, involves arranging active road studs 10 in a sequential order. The end result of the sub-operation is a list having a sequential order of active road studs 10. The list lists the first active road stud, the second active road stud, the third active road stud, ... and the last active road stud in the sequential order. The last active road stud in the sequence transmits a signal indicative of the list to base station 42.

[0069] As described, two potential implementations may be implemented for arranging active road studs 10 in a sequential order. The first implementation involves measuring the distance based on the position information (e.g., from GNSS, but could be any other means of the active road studs establishing their location in some co-ordinate system) of each active road stud as shared by the communication. The second implementation is direct measurement of distance using the actual communication, e.g., UWB.

[0070] Further, implementations of arranging active road studs 10 in a sequential order may only properly function when there is a single line of active road studs or at least there is some other way for active road studs belonging to a single line to self-identify (e.g., different colors being used at the sides of the road compared to the middle).

[0071] Following the receipt of the list of active road studs 10 in the sequential order, the operation for controlling the active road studs to make an operation change sequentially further includes base station 42 transmitting a command for receipt by active road studs 10, as indicated by process block 86. This command includes information indicative of a type of operation change that the active road studs are to make. This command further includes informationindicative of future times at which active road studs 10 are to respectively make the operation change per their sequential order according to the list. For instance, the information indicates that the first active road stud is to make the operation change at 7:57:00 pm, the second active road stud is to make the operation change at 7:57:02 pm, the third active road stud is to make the operation change at 7:57:04 pm, etc.

[0072] The operation further includes active road studs 10 keeping track of time, such as the manner described above, as indicated by process block 88. The active road studs execute the operation change at the respective times per their sequential order, as indicated by process block 90, whereby the active road studs execute the commanded operation change sequentially.

[0073] As described, the operation for controlling a set of active road studs 10 to make an operation change sequentially involves the active road studs working out their order automatically in support of being able to perform sequential changes. To this end, optionally in an initial configuration mode, the first active road stud in a sequence is identified and instructed to initiate the automated process. Following initiation, the first active road stud polls all other active road studs that are within communication range of the first active road stud. In turn, the first active road stud measures the distance to each other active road stud and records the distance against the identification of each other active road stud. The list is ordered by distance by the first active road stud.

[0074] The first active road stud identifies its closest neighboring active road stud from the list. The first active road stud transmits a message to its closest neighboring active road stud to tell that active road stud that it is the second active road stud in the sequence.

[0075] The second active road stud repeats this process, except that the second active road stud excludes the first active road stud from consideration of its closest neighboring active road stud. Each active road stud in turn repeats this process as they are told their sequence number by the preceding active road stud, passing on a list of the active road studs already in the sequence. For a long stretch of roadway, this list could become too long to keep sharing with every active road stud. For practical purposes, the list could be limited to a list of the most recent X active road studs. Earlier active road studs, even if detected, will be further away andhence not appear as the next neighboring active road stud in the sequence. When an active road stud cannot find another active road stud not already in the list and within a predefined distance (i.e., a predefined maximum allowed spacing between the active road studs) that active road stud is identified as being the last in the sequence and the length of the chain of active road studs is known. This has the concept of a maximum allowed spacing.

[0076] Another concept when automatically working out the sequence of the active road studs is for the active road studs to be able to flag up automatically when there is an error or likely issue. Hence, at each step where an active road stud establishes the distance to the closest neighboring active road stud (excluding the preceding active road stud) is outside of a range that is valid for the layout being deployed along the road, e.g., when the active road stud is missed or faulty the distance to the next sequential active road stud will be approximately double that typically expected, the active road stud automatically flags up.

[0077] Further, in some implementations (e.g., long roadways) the full list of all active road studs in the sequence may not be communicated to the last active road stud. Hence, it cannot be depended on this list being available entirely from the last active road stud for this active road stud to transmit to the base station. Alternatives that are allowed for is that each active road stud communicates its position in the sequence to the base station, or some sufficient subset of the active road studs communicate the partial sequential lists that they are aware of in order to provide the complete list.

[0078] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the present invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the present invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the present invention.

Claims

WHAT IS CLAIMED IS:

1. A method for use with active road studs installed along a roadway, the method comprising: receiving, by the active road studs, a command from a base station, the command including information indicative of an operation change that the active road studs are to make and a future time at which the active road studs are to make the operation change; measuring time by each active road stud using a source of timing information common to the active road studs so that the active road studs have the same measure of the future time; and executing, by the active road studs, the operation change at the future time as measured by the active road studs whereby the active road studs execute the operation change synchronously.

2. The method of claim 1 wherein: the step of measuring time by each active road stud includes using a global navigation satellite system (GNSS) transceiver of the active road stud.

3. The method of claim 1 wherein: the operation change is for each active road stud to turn on a light-emitting diode (LED) of the active road stud; and the step of executing includes the active road studs turning on the LEDs at the future time as measured by the active road studs whereby the active road studs turn on the LEDs synchronously.

4. The method of claim 1 wherein: the operation change is for each active road stud to turn off a light-emitting diode (LED) of the active road stud; andthe step of executing includes the active road studs turning off the LEDs at the future time as measured by the active road studs whereby the active road studs turn off the LEDs synchronously.

5. The method of claim 1 wherein: the operation change is for each active road stud to change a color of light emitted by the active road stud; and the step of executing includes the active road studs changing the color of emitted light at the future time as measured by the active road studs whereby the active road studs change the color of emitted light synchronously.

6. The method of claim 1 further comprising: receiving, by a second set of active road studs installed along the roadway, a second command from a second base station, the second command including information indicative of the operation change and the future time; measuring time by each active road stud of the second set of active road studs using the source of timing information so that the second set of active road studs have the same measure of the future time; and executing, by the second set of active road studs, the operation change at the future time as measured by the second set of active road studs whereby all of the active road studs execute the operation change synchronously.

7. The method of claim 1 wherein: the future time at which the active road studs are to make the operation change is the same for each active road stud whereby in executing the operation change synchronously the active road studs execute the operation change simultaneously.

8. The method of claim 1 wherein:the future time at which the active road studs are to make the operation change is different for each active road stud whereby in executing the operation change synchronously the active road studs execute the operation change sequentially.

9. A method for use with active road studs installed along a roadway, the method comprising: transmitting, by each active road stud, a message to a base station, the message of each active road stud including information indicative of a time at which the active road stud transmitted the message as measured by the active road stud; receiving, by each active road stud, a command from the base station, the command for each active road stud including information indicative of an operation change that the active road studs are to make and a future time at which the active road stud is to make the operation change relative to the time at which the active road stud transmitted the message as measured by the active road stud; and executing, by each active road stud, the operation change at the future time at which the active road stud is to make the operation change whereby the active road studs execute the operation change synchronously.

10. The method of claim 9 wherein: the operation change is for each active road stud to turn on a light-emitting diode (LED) of the active road stud; and the step of executing includes each active road stud turning on the LED of the active road stud at the future time at which the active road stud is to make the operation change whereby the active road studs turn on the LEDs synchronously.

11. The method of claim 9 wherein: the operation change is for each active road stud to turn off a light-emitting diode (LED) of the active road stud; andthe step of executing includes each active road stud turning off the LED of the active road stud at the future time at which the active road stud is to make the operation change whereby the active road studs turn off the LEDs synchronously.

12. The method of claim 9 wherein: the operation change is for each active road stud to change a color of light emitted by the active road stud; and the step of executing includes each active road stud changing the color of emitted light at the future time at which the active road stud is to make the operation change whereby the active road studs change the color of emitted light synchronously.

13. The method of claim 9 wherein: in executing the operation change synchronously the active road studs execute the operation change simultaneously.

14. The method of claim 9 wherein: in executing the operation change synchronously the active road studs execute the operation change sequentially.

15. A method for use with active road studs installed along a roadway, the method comprising: arranging the active road studs in a sequential order; receiving, by the active road studs, a command from a base station, the command including information indicative of an operation change that the active road studs are to make and future times at which the active road studs are to respectively make the operation change according to their arrangement in the sequential order; and executing, by each active road stud, the operation change at the future time at which the active road stud is make the operation change whereby the active road studs execute the operation change sequentially.

16. The method of claim 15 wherein: the sequential order is based on positioning of the active road studs along the roadway.

17. The method of claim 15 wherein the step of arranging the active road studs in the sequential order includes: identifying one of the active road studs as being a first active road stud in the sequential order; identifying, by the first active road stud, based on a polling signal transmitted by the first active road stud, the one of the active road studs closest to the first active road stud as being a second active road stud in the sequential order; and identifying, by the second active road stud, based on a polling signal transmitted by the second active road stud, the one of the active road studs closest to the second active road stud other than the first active road stud as being a third active road stud in the sequential order.

18. The method of claim 15 wherein: the command further includes information indicative of a second operation change that the active road studs are to make and future times at which the active road studs are to respectively make the second operation change according to their arrangement in the sequential order; and the step of executing further includes executing, by each active road stud, the second operation change at the future time at which the active road stud is make the second operation change whereby the active road studs execute the second operation change sequentially.

19. The method of claim 18 wherein: the operation change is for each active road stud to turn on a light-emitting diode (LED) of the active road stud and the second operation change is for each active road stud to turn off the LED of the active road stud; andthe step of executing includes (i) each active road stud turning on the LED of the active road stud at the future time at which the active road stud is to make the operation change whereby the active road studs turn on the LEDs in the sequential order and (ii) each active road stud turning off the LED of the active road stud at the future time at which the active road stud is to make the second operation change whereby the active road studs turn off the LEDs sequentially.

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