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EP-4500216-B1 - METHOD FOR ASSET TRACKING, ASSET GROUPING, AND ERROR RECOVERY

EP4500216B1EP 4500216 B1EP4500216 B1EP 4500216B1EP-4500216-B1

Inventors

  • FELDMAN, ALEXANDER
  • HESS, PHILLIP, B.
  • KRATZ, Philip, Adam
  • MIOCINOVIC, SRDJAN
  • LU, Jonathan, Shiao-En

Dates

Publication Date
20260506
Application Date
20230420

Claims (13)

  1. A method (S100) comprising: • during a first time period: ∘ generating a response schedule for a first asset tag (S120), the response schedule defining: ▪ a sequence of trigger times for transmitting a sequence of unicast triggers; and ▪ a sequence of wake windows, each wake window in the sequence of wake windows intersecting a trigger time in the sequence of trigger times; ∘ at a first node in a set of nodes: ▪ broadcasting a first configuration message to the first asset tag via a configuration channel (S130), the first configuration message comprising the response schedule; ∘ at the first asset tag: ▪ in response to absence of configuration data, transitioning a transceiver of the first asset tag to the configuration channel (S140); ▪ receiving the first configuration message via the configuration channel (S142); ▪ configuring the first asset tag based on the first configuration message (S144); and ▪ in response to a time duration until a first wake window, in the sequence of wake windows, exceeding a threshold time duration, entering a sleep mode (S146); and • during a second time period: ∘ at the first node in the set of nodes, ▪ based on a first trigger time in the sequence of trigger times, broadcasting a first unicast trigger, in the sequence of unicast triggers, via a ranging channel (S150); ∘ at the first asset tag: ▪ based on the first wake window, in the sequence of wake windows, entering a wake mode (S162); ▪ in response to receiving the first unicast trigger via the ranging channel, transmitting a first ranging signal (S166); and ▪ in response to transmitting the first ranging signal, entering the sleep mode (S168); and ∘ at the set of nodes: ▪ receiving the first ranging signal (S152); and • deriving a first location of the first asset tag during the second time period based on instances of the first ranging signal received by the set of nodes (S154).
  2. The method of Claim 1: • wherein broadcasting the first configuration message to the first asset tag via the configuration channel comprises: ∘ broadcasting the first configuration message to the first asset tag via the configuration channel associated with a first frequency; and • wherein broadcasting the first unicast trigger via the ranging channel comprises: ∘ broadcasting the first unicast trigger via the ranging channel associated with a second frequency range excluding the first frequency.
  3. The method of Claim 1: • wherein entering the sleep mode comprises, by the first asset tag: ∘ disabling the transceiver of the first asset tag; ∘ transitioning a processor of the first asset tag into a hibernate mode; and ∘ maintaining power supply from a battery of the first asset tag to a clock and a motion sensor of the first asset tag; and • wherein entering the wake mode comprises, by the first asset tag: ∘ enabling the transceiver of the first asset tag; and ∘ transitioning the processor of the first asset tag into an active mode.
  4. The method of Claim 1, further comprising, • during a third time period: ∘ at the first node in the set of nodes: ▪ based on a second trigger time in the sequence of trigger times, broadcasting a second unicast trigger, in the sequence of unicast triggers, via the ranging channel; ∘ at the first asset tag: ▪ based on a second wake window, in the sequence of wake windows, entering the wake mode; ▪ in response to receiving the second unicast trigger via the ranging channel, transmitting a second ranging signal; and ▪ in response to transmitting the second ranging signal, entering the sleep mode; and ∘ at the set of nodes: ▪ receiving the second ranging signal; and • deriving a second location of the first asset tag based on instances of the second ranging signal received by the set of nodes.
  5. The method of Claim 1, further comprising, during a third time period: • at the first node in the set of nodes: ∘ based on a second trigger time in the sequence of trigger times, broadcasting a second unicast trigger via the ranging channel; and • at the first asset tag: ∘ based on a second wake window in the sequence of wake windows, entering the wake mode; ∘ in response to absence of receipt of the second unicast trigger via the ranging channel, transitioning the transceiver of the first asset tag to the configuration channel; ∘ receiving a second configuration message, comprising system time of the set of nodes, via the configuration channel; and ∘based on the second configuration message, updating a clock of the first asset tag according to the system time of the set of nodes.
  6. The method of Claim 1: • further comprising distributing an encryption key to the first asset tag; • wherein broadcasting the first configuration message to the first asset tag via the configuration channel comprises: ∘ generating an encrypted configuration message by encrypting the first configuration message; and ∘ broadcasting the encrypted configuration message to the first asset tag via the configuration channel; and • wherein receiving the first configuration message via the configuration channel comprises: ∘ decrypting the encrypted configuration message via the encryption key.
  7. The method of Claim 1: • wherein receiving the first configuration message via the configuration channel comprises: ∘accessing the response schedule in the first configuration message; and ∘ accessing a first asset tag identifier in the first configuration message; and • wherein configuring the first asset tag based on the first configuration message comprises: ∘ in response to the first asset tag identifier in the first configuration message matching a second asset tag identifier of the first asset tag: ▪ synchronizing a clock of the first asset tag to a system time of the set of nodes; and ▪ configuring the first asset tag to transition between the sleep mode and the wake mode according to the response schedule.
  8. The method of Claim 1: ∘ wherein generating the response schedule comprises generating the response schedule defining: ▪ a second wake window associated with a motion sensor signal; • further comprising during a third time period: ∘ at the first asset tag: ▪ in response to receiving the motion sensor signal from a motion sensor in the first asset tag: • entering a wake mode for a duration of the second wake window; and • transmitting a second ranging signal via the ranging channel during the second wake window; and ▪ in response to transmitting the second ranging signal, entering the sleep mode; and ∘ at the set of nodes: ▪ receiving the second ranging signal; and • further comprising deriving a second location of the first asset tag based on instances of the second ranging signal received by the set of nodes.
  9. The method of Claim 8, further comprising, during the first time period: • at the first asset tag: ∘ in response to receiving a series of motion sensor signals indicating that the first asset tag is in motion: ▪ entering the wake mode; ▪ transmitting a series of ranging signals at a time interval specified by the response schedule via the ranging channel; and ▪ entering the sleep mode; and • at the set of nodes: ∘ receiving the series of ranging signals; and ∘ deriving a first series of locations of the first asset tag based on the instances of the series of ranging signals received by the set of nodes.
  10. The method of Claim 8, further comprising: • prior to the first time period: ∘ at the first asset tag: ▪ receiving a set of unicast queries from the set of nodes; and ▪ transmitting a unicast response to the set of nodes; and • at the set of nodes: ∘calculating a third location of the first asset tag based on instances of the unicast response received by the set of nodes.
  11. The method of Claim 10, further comprising: • calculating a distance between the second location and the third location of the first asset tag; • in response to the distance exceeding a threshold distance, generating a notification indicating that an asset associated with the first asset tag has been moved by the distance exceeding the threshold distance; and • transmitting the notification to a device of an operator of a target environment containing the first asset tag.
  12. The method of Claim 8, wherein deriving the second location of the first asset tag comprises: • for each node in the set of nodes: ∘ based on a time of flight of the second ranging signal received by the node, deriving a distance, in a set of distances, between the first asset tag and the node; and • at the set of nodes, deriving the second location of the first asset tag based on the set of distances.
  13. The method of Claim 8, wherein receiving the configuration message via the configuration channel comprises: • at the first asset tag: ∘ receiving the configuration message via a first frequency associated with the configuration channel; ∘ transmitting the second ranging signal during the second wake window; and ∘ transmitting the second ranging signal at second frequency within a second frequency range excluding the first frequency.

Description

TECHNICAL FIELD This invention relates generally to the field of asset tags and more specifically to a new and useful method for asset tag tracking, grouping, and error recovery in the field of asset tracking. BACKGROUND Known asset tags and systems and methods for asset tag tracking are disclosed in US2018/227850. SUMMARY OF INVENTION According to one aspect, there is provided a method according to claim 1. The invention is defined by the independent claims. Further embodiments of the invention are defined by the dependent claims. Although the invention is only defined by the claims, the below embodiments, examples and aspects are present for aiding in understanding the background and advantages of the invention. BRIEF DESCRIPTION OF THE FIGURES FIGURE 1 is a schematic representation of a method;FIGURE 2 is a schematic representation of one variation of the method;FIGURE 3 is a schematic representation of one variation of the method; andFIGURE 4 is a schematic representation of one variation of the method. DESCRIPTION OF THE EMBODIMENTS The following description of embodiments of the invention is not intended to limit the invention to these embodiments but rather to enable a person skilled in the art to make and use this invention. Variations, configurations, implementations, example implementations, and examples described herein are optional and are not exclusive to the variations, configurations, implementations, example implementations, and examples they describe. The invention described herein can include any and all permutations of these variations, configurations, implementations, example implementations, and examples. 1. Method As shown in FIGURES 1-4, a method S100 includes, at a first time, generating a first response schedule for a first asset tag in Block S120, the first response schedule defining: a sequence of trigger times for transmitting a sequence of unicast triggers; and a sequence of wake windows, each wake window in the sequence of wake windows intersecting a trigger time in the first sequence of trigger times. In this variation, the method S100 further includes, at a first node of a set of nodes, broadcasting a first configuration message to the first asset tag via a configuration channel in Block S130, the first configuration message including the first response schedule, and at the first asset tag: in response to absence of configuration data, transitioning a transceiver of the first asset tag to the configuration channel in Block S140; receiving the first configuration message via the configuration channel in Block S142; configuring the first asset tag based on the first configuration message in Block S144; and, in response to a time duration until a first wake window, in the sequence of wake windows, exceeding a threshold time duration, entering a sleep mode in Block S146. In this variation, the method S100 further includes, at a second time: at the first node in the set of nodes, based on a first trigger time in the sequence of trigger times, broadcasting the first unicast trigger, in the sequence of unicast triggers, via a ranging channel in Block S150. The method S100 also includes, at the second time and at the first asset tag: based on the first wake window, entering a wake mode in Block S162; in response to receiving the first unicast trigger via the ranging channel, transmitting a first ranging signal in Block S166; in response to transmitting the first ranging signal, entering the sleep mode Block S168; and, at the set of nodes receiving the first ranging signal in Block S152, deriving a first location of the first asset tag at the second time based on instances of the first ranging signal received by the set of nodes in Block S154. 1.1 Variation: Motion-sensor-activated Unicast Ranging As shown in FIGURES 1-4, the method S100 includes, during a first time period, generating a first response schedule for a first asset tag in Block S120, the first response schedule defining: a first trigger time for transmitting a first unicast trigger; a first wake window intersecting the first trigger time; and a second wake window associated with a motion sensor signal. In this variation, the method S100 also includes, at a first node of a set of nodes, broadcasting a first configuration message, including the first response schedule, to the first asset tag via a configuration channel in Block S130, and at the first asset tag: in response to absence of configuration data, transitioning a transceiver of the first asset tag to the configuration channel in Block S140; receiving the first configuration message via the configuration channel in Block S142; configuring the first asset tag based on the first configuration message in Block S144; and, in response to a time duration until a first wake window, in the sequence of wake windows, exceeding a threshold time duration, entering a sleep mode in Block S146. In this variation, the method S100 also includes, during a second time period, at the