IPC분류정보
| 국가/구분 |
United States(US) Patent
등록
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| 국제특허분류(IPC7판) |
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| 출원번호 |
US-0200735
(2008-08-28)
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| 등록번호 |
US-8606501
(2013-12-10)
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발명자
/ 주소 |
- Hannah, Stephen E.
- Carter, Scott J.
- James, Jesse M.
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| 출원인 / 주소 |
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| 대리인 / 주소 |
Knobbe, Martens, Olson & Bear, LLP
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| 인용정보 |
피인용 횟수 :
14 인용 특허 :
46 |
초록
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A vehicle tracking system includes a wheel containing sensor circuitry capable of sensing various types of conditions, such as wheel rotation, wheel vibration caused by skidding, and specific electromagnetic and/or magnetic signals indicative of particular wheel locations. The sensor circuitry is co
A vehicle tracking system includes a wheel containing sensor circuitry capable of sensing various types of conditions, such as wheel rotation, wheel vibration caused by skidding, and specific electromagnetic and/or magnetic signals indicative of particular wheel locations. The sensor circuitry is coupled to an RF transceiver, which may but need not be included within the wheel. The wheel may also include a brake mechanism. In one embodiment, the wheels are placed on shopping carts and are used to collect and monitor shopping cart status and location data via a wireless network. The collected data may be used for various purposes, such as locking the wheel of an exiting cart if the customer has not paid, estimating numbers of queued carts, stopping wheel skid events that occur during mechanized cart retrieval, store planning, and providing location-based messaging to customers.
대표청구항
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1. A system for monitoring shopping cart usage in the vicinity of a store, the system comprising: a plurality of access points mounted in a vicinity of the store; anda plurality of shopping carts, each shopping cart including a wheel assembly that comprises a battery-powered cart transceiver that is
1. A system for monitoring shopping cart usage in the vicinity of a store, the system comprising: a plurality of access points mounted in a vicinity of the store; anda plurality of shopping carts, each shopping cart including a wheel assembly that comprises a battery-powered cart transceiver that is configured to communicate wirelessly with the access points on a wireless network, each cart transceiver configured to operate as a uniquely addressable node on the wireless network;said access points and cart transceivers programmed to communicate with each other on said wireless network using a non-standard wireless communications protocol in which the cart transceivers (1) generate received signal strength (RSSI) measurements based on transmissions from the access points, and (2) use said RSSI measurements to detect entry into particular zones that correspond to particular access points, wherein each cart transceiver is configured to modify its communication behavior in response to detecting that it has entered into a zone corresponding to an access point. 2. The system of claim 1, wherein each cart transceiver is configured to generate, for a particular access point, a filtered RSSI value based on a plurality of RSSI measurements, and to use the filtered RSSI value to determine whether to respond to a transmission from the access point. 3. The system of claim 1, wherein at least a first access point of said plurality of access points is configured to communicate an RSSI threshold value to the cart transceivers, and the cart transceivers are configured to use the RSSI threshold value, in combination with RSSI measurements, to determine whether to respond to transmissions from said first access point. 4. The system of claim 1, wherein the access points are configured to transmit information to the cart transceivers at a bit rate that is substantially higher than a bit rate used by the cart transceivers to transmit information to the access points. 5. The system of claim 4, wherein the access points are additionally configured to transmit at a higher level power than the cart transceivers. 6. The system of claim 1, wherein each cart transceiver is configured to automatically switch, according to a programmable duty cycle, between (1) a low power state in which the cart transceiver is not capable of receiving transmissions from the access points, and (2) an active state in which the cart transceiver listens for transmissions from the access points. 7. The system of claim 6, wherein each cart transceiver is configured to adjust, based on transmissions it receives from the access points, a frequency with which it switches to said active state. 8. The system of claim 6, wherein each cart transceiver is capable of being placed into a mode in which it wakes up more frequently when detecting RSSI levels above a specified threshold. 9. The system of claim 1, wherein the access points are configured to send commands to the cart transceivers using a command set that includes a plurality of commands. 10. The system of claim 9, wherein at least some of the wheel assemblies include braking mechanisms, and the command set includes commands for activating and deactivating said braking mechanisms. 11. The system of claim 9, wherein at least some of the wheel assemblies include braking mechanisms, and the command set includes a command that causes a cart transceiver to temporarily disregard a braking signal that ordinarily causes the cart transceiver to activate the braking mechanism. 12. The system of claim 9, wherein the command set includes a command that instructs a cart transceiver to report its entry into an access-point-specific zone. 13. The system of claim 9, wherein the command set includes a status request command to which a cart transceiver responds by transmitting at least one of the following types of status information: (a) lock/unlock status of the wheel assembly, (b) number of lock/unlock cycles performed by the wheel assembly. 14. The system of claim 9, wherein the access points are configured to transmit at least some of said commands together with RSSI threshold values that are used by the cart transceivers to determine whether to respond. 15. The system of claim 9, wherein at least some of the access points are configured to use both unicast and multi-cast addressing to send commands to the cart transceivers. 16. The system of claim 1, wherein the system comprises at least one node that is programmed to use event data collected through bi-directional communications between a cart transceiver and one or more of the access points to determine whether a corresponding shopping cart is authorized to exit the store. 17. The system of claim 1, wherein each access point is mounted to create a respective zone corresponding to an antenna footprint of the respective access point, and each cart transceiver is configured to detect, and to report on said wireless network, its entry into particular zones. 18. The system of claim 1, wherein at least one of the access points is configured to continuously transmit an unconditional lock command to create a lock zone in which shopping cart use is not permitted, and the cart transceivers are responsive to said unconditional lock command by placing their respective wheel assemblies in a locked state. 19. The system of claim 1, wherein at least one of the cart transceivers (1) includes a VLF (Very Low Frequency) receiver that is separate from a radio frequency (RF) transceiver used for communications with the access points, and (2) is configured to report, on said wireless network, VLF signal detection events in which a VLF signal is detected with said VLF receiver. 20. The system of claim 1, wherein each cart transceiver is housed within a respective shopping cart wheel. 21. A system for monitoring usage of a human-propelled cart, the system comprising: a wheel assembly that is adapted to attach to a cart, said wheel assembly comprising a wheel, and comprising a battery-powered cart transceiver that is configured to communicate wirelessly with a plurality of access points on a wireless network, said cart transceiver configured to operate as a uniquely addressable node on the wireless network;said cart transceiver programmed to communicate with the access points on the wireless network using a non-standard wireless communications protocol in which the cart transceiver uses received signal strength (RSSI) measurements generated based on communications with the access points to detect entry of the wheel assembly into particular zones that correspond to particular access points, said cart transceiver further programmed to modify its communication behavior in response to detecting entry into a zone that corresponds to an access point. 22. The system of claim 21, wherein the cart transceiver is configured to generate, for a particular access point, a filtered RSSI value based on a plurality of RSSI measurements, and to use the filtered RSSI value to determine whether to respond to a transmission from the access point. 23. The system of claim 21, wherein the cart transceiver is configured to use an RSSI threshold value received from an access point, in combination with an RSSI value generated by the cart transceiver for said access point, to determine whether to respond to a transmission from said access point. 24. The system of claim 21, wherein cart transceiver is configured to receive information from the access points at a bit rate that is substantially higher than a bit rate used by the cart transceiver to transmit information to the access points. 25. The system of claim 21, wherein the cart transceiver is configured to automatically switch, according to a programmable duty cycle, between (1) a low power state in which the cart transceiver does not listen for transmissions from the access points, and (2) an active state in which the cart transceiver listens for transmissions from the access points. 26. The system of claim 25, wherein the cart transceiver is configured to adjust, based on transmissions it receives from the access points, a frequency with which it switches to said active state. 27. The system of claim 25, wherein the cart transceiver is capable of being placed into a mode in which it wakes up more frequently when detecting RSSI levels above a specified threshold. 28. The system of claim 21, wherein the cart transceiver implements a command set for responding to commands received from the access points, said command set including a plurality of commands. 29. The system of claim 28, wherein the wheel assembly includes a braking mechanism, and the command set includes commands for activating and deactivating said braking mechanism. 30. The system of claim 28, wherein the wheel assembly includes a braking mechanisms, and the command set includes a command that causes the cart transceiver to temporarily disregard a braking signal that ordinarily causes the cart transceiver to activate the braking mechanism. 31. The system of claim 28, wherein the command set includes a command that instructs the cart transceiver to report its entry into an access-point-specific zone. 32. The system of claim 28, wherein the command set includes a status request command to which the cart transceiver responds by transmitting at least one of the following types of status information: (a) lock/unlock status of the wheel assembly, (b) number of lock/unlock cycles performed by the wheel assembly. 33. The system of claim 21, further comprising an executable program that is configured to use event data collected through bi-directional communications between the cart transceiver and one or more of the access points to determine whether the cart is authorized to pass through an exit. 34. The system of claim 21, wherein the cart transceiver is configured to detect, and to report on said wireless network, its entry into particular access-point-specific zones. 35. The system of claim 21, wherein the cart transceiver includes a VLF (Very Low Frequency) receiver that is separate from a radio frequency (RF) transceiver used for communications with the access points, and is configured to report, on said wireless network, VLF signal detection events. 36. The system of claim 21, wherein the cart transceiver is housed within said wheel. 37. The system of claim 21, wherein the cart transceiver is programmed to modify its communication behavior in response to detecting entry into said zone by modifying a wake up interval used by the cart transceiver for listening for transmissions on the wireless network. 38. The system of claim 21, wherein the cart transceiver is programmed to modify its communication behavior in response to detecting entry into said zone by responding to commands received from said access point. 39. The system of claim 21, wherein the cart transceiver generates said RSSI measurements. 40. The system of claim 21, wherein at least one of the access points is mounted above ground and includes a directional antenna that is angled downward to focus radiation toward a ground surface on which the cart moves.
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