Methods and systems for scheduling the transmission of localization signals and operating self-localizing apparatus
Localization systems and methods for transmitting timestampable localization signals from anchors according to one or more transmission schedules. The transmission schedules may be generated and updated to achieve desired positioning performance. For example, one or more anchors may transmit localization signals at a different rate than other anchors, the anchor transmission order can be changed, and the signals can partially overlap. In addition, different transmission parameters may be used to transmit two localization signals at the same time without interference. A self-localizing apparatus is able to receive the localization signals and determine its position. The self-localizing apparatus may have a configurable receiver that can select to receive one of multiple available localization signals. The self-localizing apparatuses may have a pair of receivers able to receive two localization signals at the same time. A bridge anchor may be provided to enable a self-localizing apparatus to seamlessly transition between two localization systems.
1. A self-localizing apparatus for determining a vehicle's position, the self-localizing apparatus composing:
a first subsystem, comprising:
a first antenna operable to receive a first radio frequency signal;
first analog reception electronics configured to amplify the first radio frequency signal;
first digital reception electronics configured to timestamp the amplified first radio frequency signal with reference to a clock signal; and
a first localization unit configured to compute a first estimate of the self-localizing apparatus' position in a coordinate system based on the timestamp of the amplified first radio frequency signal; and
a second subsystem operably coupled to the first subsystem, comprising:
a second antenna operable to receive a second radio frequency signal;
second analog reception electronics configured to amplify the second radio frequency signal;
second digital reception electronics configured to timestamp the amplified second radio frequency signal with reference to a clock signal; and
a second localization unit configured to compute a second estimate of the self-localizing apparatus' position in a coordinate system based on the timestamp of the amplified second radio frequency signal; and
wherein each of the first subsystem and the second subsystem is configured to be selectively used to control the vehicle without relying on the other subsystem.
2. The self-localizing apparatus of claim 1 , wherein:
the first subsystem further comprises a first clock, wherein the first digital reception electronics are configured to timestamp the amplified first radio frequency signal with reference to a first clock signal generated by the first clock; and
the second subsystem further comprises a second clock, wherein the second digital reception electronics are configured to timestamp the amplified second radio frequency signal with reference to a second clock signal generated by the second clock.
3. The self-localizing apparatus of claim 2 , wherein:
the first subsystem further comprises a first synchronization unit configured to compute a clock correction for the first clock;
the second subsystem further comprises a second synchronization unit configured to compute a clock correction for the second clock.
4. The self-localizing apparatus of claim 1 , wherein:
the first subsystem further comprises a first sensor for sensing at least one of a position, orientation, or velocity of the self-localizing apparatus relative to an external reference frame, wherein the first localization unit is configured to compute the first estimate of the self-localizing apparatus' position further based on a first signal generated by the first sensor; and
the second subsystem further comprises a second sensor for sensing at least one of a position, orientation, or velocity of the self-localizing apparatus relative to an external reference frame, wherein the second localization unit is configured to compute the second estimate of the self-localizing apparatus' position further based on a second signal generated by the second sensor.
5. The self-localizing apparatus of claim 4 , wherein:
the first sensor is a first global property sensor; and
the second sensor is a second global property sensor.
6. The self-localizing apparatus of claim 1 , wherein:
the first subsystem further comprises a first compensation unit, wherein the first localization unit is configured to compute the first estimate of the self-localizing apparatus' position further based on data provided by the first compensation unit; and
the second subsystem further comprises a second compensation unit, wherein the second localization unit is configured to compute the second estimate of the self-localizing apparatus' position further based on data provided by the second compensation unit.
7. The self-localizing apparatus of claim 1 , further comprising a clock, wherein:
the first digital reception electronics are configured to timestamp the amplified first radio frequency signal with reference to a first clock signal generated by the clock; and
the second digital reception electronics are configured to timestamp the amplified second radio frequency signal with reference to the first clock signal generated by the clock.
8. The self-localizing apparatus of claim 7 , further comprising a synchronization unit wherein the synchronization unit is configured to compute a clock correction for the clock.
9. The self-localizing apparatus of claim 1 , further comprising a sensor for sensing at least one of a position, orientation, or velocity of the self-localizing apparatus relative to an external reference frame, wherein:
the first localization unit is configured to compute the first estimate of the self-localizing apparatus' position further based on a first signal generated by the sensor; and
the second localization unit is configured to compute the second estimate of the self-localizing apparatus' position further based on the first signal generated by the sensor.
10. The self-localizing apparatus of claim 9 , wherein the sensor is a global property sensor.
11. The self-localizing apparatus of claim 1 , further comprising a compensation unit, wherein:
the first localization unit is configured to compute the first estimate of the self-localizing apparatus' position further based on data provided by the compensation unit; and
the second localization unit is configured to compute the second estimate of the self-localizing apparatus' position further based on data provided by the compensation unit.
12. A self-localizing apparatus for use in a localization network comprising a plurality of anchors configured to transmit radio frequency signals, the self-localizing apparatus comprising:
an antenna operable to receive radio frequency signals from the localization network;
analog reception electronics configured to amplify the radio frequency signals received by the antenna;
digital reception electronics configured to timestamp the amplified radio frequency signals with reference to a first clock signal to generate a plurality of timestamps; and
a localization unit configured to:
compute an estimate of the self-localizing apparatus' position in a coordinate system based on the timestamps;
determine to receive a selected future radio frequency signal from at least two future radio frequency signals;
configure at least one of the antenna, the analog reception electronics, and the digital reception electronics to receive the selected radio frequency signal; and
compute an updated estimate of the self-localizing apparatus' position in the coordinate system based on the received selected radio frequency signal.
13. The self-localizing apparatus of claim 12 , further comprising digital and analog transmission electronics configured to transmit the self-localizing apparatus' position to at least one of the plurality of anchors.
14. The self-localizing apparatus of claim 12 , wherein the received radio frequency signals each comprise a payload and wherein the digital reception electronics are configured to extract the payload.
15. The self-localizing apparatus of claim 14 , wherein the payload identifies at least one anchor of the plurality of anchors that is configured to transmit a localization signal during at least one future time slot.
16. The self-localizing apparatus of claim 12 , wherein the localization unit is configured to determine to receive the selected future radio frequency signal based on the location of the anchor configured to transmit the selected future radio frequency signal and a variance associated with the computed estimate of the self-localizing apparatus' position.
17. The self-localizing apparatus of claim 12 , wherein the at least two future radio frequency signals partially overlap in time and wherein the localization unit is configured to receive the entire selected future radio frequency signal and only a portion of another of the at least two future radio frequency signals.
18. The self-localizing apparatus of claim 12 , wherein the at least two future radio frequency signals use different preamble codes.
19. The self-localizing apparatus of claim 12 , wherein the at least two future radio frequency signals are transmitted by different localization networks.
20. The self-localizing apparatus of claim 12 wherein the localization unit is further configured to compute the estimate of the self-localizing apparatus' position in the coordinate system based on known locations of the anchors configured to transmit the radio frequencies received by the antenna.
21. A method for determining a vehicle's position using a self-localizing apparatus that comprises a first subsystem and a second subsystem, the method comprising:
receiving, using a first antenna of the first subsystem, a first radio frequency signal;
amplifying, using first analog reception electronics of the first subsystem, the first radio frequency signal;
timestamping, using first digital reception electronics of the first subsystem, the amplified first radio frequency signal with reference to a clock signal;
computing, using a first localization unit of the first subsystem, a first estimate of the self-localizing apparatus' position in a coordinate system;
receiving, using a second antenna of the second subsystem, a second radio frequency signal;
amplifying, using second analog reception electronics of the second subsystem, the second radio frequency signal;
timestamping, using second digital reception electronics of the second subsystem, the amplified second radio frequency signal with reference to a clock signal;
computing, using a second localization unit of the second subsystem, a second estimate of the self-localizing apparatus' position in a coordinate system; and
using one of the first subsystem and the second subsystem without relying on the other subsystem to control the vehicle.
22. A localization method for a self-localizing apparatus in a localization network comprising a plurality of anchors configured to transmit radio frequency signals, the method comprising:
receiving, using an antenna, radio frequency signals from the localization network;
amplifying, using analog reception electronics, the radio frequency signals received by the antenna;
timestamping, using digital reception electronics, the amplified radio frequency signals with reference to a first clock signal to generate a plurality of timestamps;
computing, using a localization unit, an estimate of the self-localizing apparatus' position in a coordinate system based on the timestamps;
determining, using the localization unit, to receive a selected future radio frequency signal from at least two future radio frequency signals;
configuring, using the localization unit, at least one of the antenna, the analog reception electronics, and the digital reception electronics to receive the selected radio frequency signal; and
computing, using the localization unit, an updated estimate of the self-localizing apparatus' position in the coordinate system based on the received selected radio frequency signal.