Ultra-wideband based vehicle access system and communication protocol for localization of a target device

Patent metadata

Field	Value
Publication number	US-10573104-B2
Application number	US-201816042397-A
Country	US
Kind code	B2
Filing date	Jul 23, 2018
Priority date	Jun 29, 2018
Publication date	Feb 25, 2020
Grant date	Feb 25, 2020

Abstract

A vehicle access system having a plurality of system nodes arranged throughout a vehicle is disclosed. The vehicle access system employs a communication protocol which utilizes two way ranging (TWR) and time distance of arrival (TDoA) localization processes to determine a position of a target portable device. The communication protocol selects the optimal combination of TWR and TDoA estimations, depending on a number of system nodes that are in communication range of the target portable device, to provide the greatest accuracy with the best power efficiency at the target portable device. Particularly, the communication protocol minimizes the number of messages sent and received by the target portable device, thereby improving the power efficiency thereof. Furthermore, the communication protocol schedules messages between the system nodes and target portable device so as to minimize the wake time of the target portable device, thereby further improving the power efficiency thereof.

First claim

What is claimed is:

1. A method of operating a vehicle access system having a plurality of system nodes arranged throughout a vehicle, the method comprising:
selecting a first set of system nodes in the plurality of system nodes, the first set of system nodes being a subset of the plurality of system nodes;
transmitting, with each system node in the first set of system nodes, a respective poll message to a target portable device and recording, with each system node in the first set of system nodes, a first timestamp at which the respective poll message is transmitted;
receiving a response message from the target portable device with a second set of system nodes in the plurality of system nodes and recording, with each system node in the second set of system nodes, a respective second timestamp at which the response message is received, the response message including one of (i) a respective third timestamp at which each respective poll message was received at the target portable device and a fourth timestamp at which the response message was transmitted and (ii) a respective wait time equal to a difference between the respective third timestamp and the fourth timestamp;
determining a respective time of flight between the target portable device and each system node in the first set of system nodes based on the respective first timestamp, the respective second timestamp, and the one of (i) the respective third timestamp and the fourth timestamp and (ii) the respective wait time;
determining a respective time difference of arrival between a first system node in the second set of system nodes and each other system node in the second set of system nodes based on the respective second timestamp recorded by the first system node in the second set of system nodes and the respective second timestamp recorded by each other system node in the second set of system nodes; and
determining a position of the target portable device relative to the vehicle based on (i) the respective time of flight between the target portable device and each system node in the first set of system nodes and (ii) the respective time difference of arrival between the first system node in the second set of system nodes and each other system node in the second set of system nodes.

2. The method of claim 1 , the selecting of the first set of system nodes further comprising:
selecting the first set of system nodes depending on a number of system nodes in the plurality of system nodes that are in communication range of the target portable device, the first set of system nodes being selected from the system nodes in the plurality of system nodes that are in communication range of the target portable device.

3. The method of claim 2 , the selecting of the first set of system nodes further comprising:
selecting a master node of the plurality of system nodes as one of the first set of system nodes in response to the master node being in communication range of the target portable device.

4. The method of claim 2 , the selecting of the first set of system nodes further comprising:
selecting only one system node as the first set of system nodes in response to more than three system nodes in the plurality of system nodes being in communication range of the target portable device; and
selecting only one system node as the first set of system nodes in response to only one system node in the plurality of system nodes being in communication range of the target portable device.

5. The method of claim 2 , the selecting of the first set of system nodes further comprising:
selecting only two system nodes as the first set of system nodes in response to only three system nodes in the plurality of system nodes being in communication range of the target portable device; and
selecting only two system nodes as the first set of system nodes in response to only two system nodes in the plurality of system nodes being in communication range of the target portable device.

6. The method of claim 2 , the selecting of the first set of system nodes further comprising:
determining the number of system nodes in the plurality of system nodes that are in communication range of the target portable device based on which system nodes in the plurality of system nodes received a previous message from the target portable device during a previous communication cycle.

7. The method of claim 1 , the selecting of the first set of system nodes further comprising:
selecting the first set of system nodes depending on at least one of (i) locations of the plurality of system nodes on the vehicle, (ii) signal strengths of messages received at the plurality of system nodes from the target portable device, and (iii) channel state information metadata for messages received at the plurality of system nodes from the target portable device.

8. The method of claim 1 further comprising:
transmitting a respective data message from each slave system node of the plurality of system nodes to a master system node of the plurality of system nodes, each respective data message including a fifth timestamp at which the respective data message is transmitted;
recording, with the master system node, respective sixth timestamps at which each respective data message is received by the master system node; and
calculating a clock offset of each of the slave system nodes with respect to the master system node based on the fifth timestamp and the respective sixth timestamps.

9. The method of claim 8 , wherein each respective data message further includes metadata with respect to at least one of (i) a signal strength of messages received at the respective slave system node from the target portable device and (ii) channel state information for messages received at the respective slave system node from the target portable device.

10. The method of claim 8 further comprising:
transmitting a synchronization message from the master system node to each of the slave system nodes, the synchronization message including a seventh timestamp at which the synchronization message is transmitted;
recording, with each of the slave system nodes, respective eighth timestamps at which the synchronization message is received by the respective slave system nodes; and
calculating the clock offset of each of the slave system nodes with respect to the master system node further based on based on the seventh timestamp and the respective eighth timestamps.

11. The method of claim 1 , the determining of the position of the target portable device relative to the vehicle further comprising:
determining a three-dimensional position of the target portable device in response to the second set of system nodes that received the response message from the target portable device including at least three system nodes.

12. The method of claim 1 , the determining of the position of the target portable device relative to the vehicle further comprising:
determining a two-dimensional position of the target portable device in response to (i) the selected first set of system nodes including only two system nodes and (ii) the second set of system nodes that received the response message from the target portable device including only two system nodes.

13. The method of claim 1 , the determining of the position of the target portable device relative to the vehicle further comprising:
determining proximity of the target portable device in response to (i) the selected first set of system nodes including only one system node and (ii) the second set of system nodes that received the response message from the target portable device including only one system node.

14. The method o

Assignees

• Bosch Gmbh Robert

Inventors

• Jain Vivek
• Rakshit Sushanta Mohan
• Coors Martin

Classifications

• G07C9/28 Primary

  the pass enabling tracking or indicating presence · CPC title

• H04W4/02

  Services making use of location information · CPC title

• H04L67/12

  specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks · CPC title

• G01S13/765

  with exchange of information between interrogator and responder · CPC title

• G07C9/00111 Primary

  Physics · mapped topic