Distributed localization systems and methods and self-localizing apparatus
A self-localizing apparatus uses timestampable signals transmitted by transceivers that are a part of a distributed localization system to compute its position relative to the transceivers. Transceivers and self-localizing apparatuses are arranged for highly accurate timestamping using digital and analog reception and transmission electronics as well as one or more highly accurate clocks, compensation units, localization units, position calibration units, scheduling units, or synchronization units. Transceivers and self-localizing apparatuses are further arranged to allow full scalability in the number of self-localizing apparatuses and to allow robust self-localization with latencies and update rates useful for high performance applications such as autonomous mobile robot control.
1. A method for adding an additional transceiver to an active transceiver network comprising at least first, second, and third transceivers with known relative locations, the method comprising:
activating the additional transceiver to receive signals;
wirelessly transmitting, using the first transceiver, a first signal;
wirelessly transmitting, using the second transceiver, a second signal;
wirelessly transmitting, using the third transceiver, a third signal, wherein the first, second, and third signals are each spread over a bandwidth that exceeds the lesser of 125 MHz and 5% of an arithmetic center frequency of the signal;
receiving, at the additional transceiver, the first, second, and third signals;
timestamping, using the additional transceiver, the reception of the first, second, and third signals;
computing, using a position calibration unit, the position of the additional transceiver relative to the first, second, and third transceivers based on:
the reception timestamps of the first, second, and third received signals; and
the known relative locations of the first, second, and third transceivers; and
wirelessly transmitting, using the additional transceiver, an additional signal.
2. The method according to claim 1 , wherein:
the transceiver network further comprises a fourth transceiver with a known location relative to the first, second, and third transceivers;
the method further comprises:
wirelessly transmitting, using the fourth transceiver, a fourth signal, wherein the fourth signal is spread over a bandwidth that exceeds the lesser of 125 MHz and 5% of an arithmetic center frequency of the signal;
receiving, at the additional transceiver, the fourth signal; and
timestamping, using the additional transceiver, the reception of the fourth signal; and
computing the position of the additional transceiver is further based on:
the reception timestamp of the fourth signal; and
the known location of the fourth transceiver relative to the first, second, and third transceivers.
3. The method of claim 1 , wherein:
the first, second, and third transceivers have clocks synchronized in at least one of clock offset or clock rate;
transmission timestamps of the first, second, and third signals are known in the synchronized clocks' time; and
computing the position of the additional transceiver is further based on the transmission timestamps of the first, second, and third signals.
4. The method of claim 3 , wherein the first, second, and third transmission timestamps are retrieved from a memory on the additional transceiver or decoded by the additional transceiver from one or more signals received by the additional transceiver.
5. The method of claim 1 , wherein the active transceiver network further comprises a fourth transceiver with a known location relative to the first, second, and third transceivers, the method comprising:
wirelessly transmitting, using the fourth transceiver, a fourth signal, wherein the fourth signal is spread over a bandwidth that exceeds the lesser of 125 MHz and 5% of an arithmetic center frequency of the signal;
receiving, at the additional transceiver, the fourth signal; and
timestamping, using the additional transceiver, the reception of the fourth signal,
wherein the computing the position of the additional transceiver is further based on:
the reception timestamp of the fourth received signal;
the known relative location of the fourth transceiver; and
transmission timestamps of the first, second, third, and fourth signals, and
wherein the computing implicitly or explicitly comprises computation of at least one of a clock offset or a clock rate between the first, second, third, and fourth transceivers and the additional transceiver.
6. The method of claim 1 , further comprising:
wirelessly transmitting, using the additional transceiver, at least one additional signal prior to the wireless transmission of the first, second, and third signals, wherein the at least one additional signal is spread over a bandwidth that exceeds the lesser of 125 MHz and 5% of an arithmetic center frequency of the signal;
storing at least one transmission timestamp of the at least one additional signal in the additional transceiver clock's time in a memory;
receiving an additional signal from the additional transceiver at the first transceiver;
receiving an additional signal from the additional transceiver at the second transceiver; and
receiving an additional signal from the additional transceiver at the third transceiver,
wherein:
a first transmission delay between a reception of a signal at the first transceiver and a corresponding transmission of a signal from the first transceiver is known;
a second transmission delay between a reception of a signal at the second transceiver and a corresponding transmission of a signal from the second transceiver is known;
a third transmission delay between a reception of a signal at the third transceiver and a corresponding transmission of a signal from the third transceiver is known; and
computing the position of the additional transceiver is further based on the first, second, and third transmission delays and the at least one transmission timestamp of the at least one additional signal stored in the memory.
7. The method of claim 6 , wherein the first, second, and third transmission delays are retrieved from a memory on the additional transceiver.
8. The method of claim 6 , wherein the first, second, and third transmission delays are decoded from one or more signals received by the additional transceiver.
9. The method of claim 1 , further comprising adjusting, using a scheduling unit, a transmission schedule of signals to include scheduled transmissions of signals from the additional transceiver.
10. The method of claim 1 , further comprising allocating, using a scheduling unit, at least one empty time division multiple access (TDMA) time slot to the additional transceiver.
11. The method of claim 1 , further comprising wirelessly transmitting a plurality of signals from the first, second, and third transceivers and the additional transceiver, wherein each of the plurality of signals comprises embedded relative position information of the transmitting transceiver.
12. The method of claim 11 , further comprising:
receiving, using a self-localizing apparatus, the plurality of signals; and
computing, using the self-localizing apparatus, a relative position of the self-localizing apparatus based on the received plurality of signals.
13. A transceiver network, comprising:
a first transceiver configured to transmit a first signal;
a second transceiver configured to transmit a second signal;
a third transceiver configured to transmit a third signal, wherein the first, second, and third signals are each spread over a bandwidth that exceeds the lesser of 125 MHz and 5% of an arithmetic center frequency of the signal;
an additional transceiver configured to:
receive the first, second, and third signals; and
timestamp the reception of the first, second, and third signals;
a position calibration unit configured to compute the position of the additional transceiver relative to the first, second, and third transceivers based on:
the reception timestamps of the first, second, and third received signals; and
known relative locations of the first, second, and third transceivers; and
a scheduling unit configured to determine a scheduled transmission time slot for the additional transceiver.
14. The transceiver network of claim 13 , further comprising:
a fourth transceiver configured to transmit a fourth signal, wherein the fourth signal is spread over a bandwidth that exceeds the lesser of 125 MHz and 5% of an arithmetic center frequency of the signal;
wherein the additional transceiver is configured to:
receive the fourth signal; and
timestamp the reception of the fourth signal; and
wherein the position calibration unit is configured to compute the position of the additional transceiver location further based on:
the reception timestamp of the fourth signal; and
a known location of the fourth transceiver relative to the first, second, and third transceivers.
15. The transceiver network of claim 13 , further comprising a synchronizing unit configured to synchronize the first, second, and third transceivers in time, wherein computing the position of the additional transceiver is further based on transmission timestamps of the first, second, and third signals in the synchronized time.
16. The transceiver network of claim 13 , wherein the additional transceiver is configured to wirelessly transmit at least one additional signal prior to the wireless transmission of the first, second, and third signals and wherein the at least one additional signal is spread over a bandwidth that exceeds the lesser of 125 MHz and 5% of an arithmetic center frequency of the signal, the network further comprising:
memory configured to store at least one transmission timestamp of the at least one additional signal in the additional transceiver clock time;
wherein the first transceiver is configured to receive an additional signal from the additional transceiver;
wherein the second transceiver is configured to receive an additional signal from the additional transceiver;
wherein the third transceiver is configured to receive an additional signal from the additional transceiver; and
wherein the position calibration unit is configured to compute the position of the additional transceiver further based on:
the at least one transmission timestamp of the at least one additional signal;
a known first transmission delay between a reception of a signal at the first transceiver and a corresponding transmission of a signal from the first transceiver;
a known second transmission delay between a reception of a signal at the second transceiver and a corresponding transmission of a signal from the second transceiver; and
a third known transmission delay between a reception of a signal at the third transceiver and a corresponding transmission of a signal from the third transceiver.
17. The transceiver network of claim 13 , wherein the scheduling unit is configured to determine the schedule transmission time slot by adjusting a transmission schedule of signals to include scheduled transmissions of signals from the additional transceiver.
18. The transceiver network of claim 13 , further comprising:
a synchronizing unit configured to synchronize the first, second, and third transceivers in time,
wherein the position calibration unit is configured to compute the position of the additional transceiver further based on transmission timestamps of the first, second, and third signals in the synchronized time.
19. The transceiver network of claim 13 , wherein the first, second, and third transceivers and the additional transceiver are each configured to:
transmit a signal; and
embed in the signal relative position information of the transmitting transceiver.
20. The transceiver network of claim 19 , further comprising:
a self-localizing apparatus configured to:
receive signals from the first, second, and third transceivers and the additional transceiver; and
compute a relative position of the self-localizing apparatus based on the received signals.