Estimation of offset between clocks in a distributed system
AssigneeTrimble Inc.
InventorsGuilherme F. Trigo, Lorenz Görcke
Life of this patent
Estimating the term…
Abstract
Some embodiments of the invention pertain to methods for estimating an offset between clocks of separate devices, for example for clock synchronization purposes. The devices are moving, at least for a period of time, with respect to each other. An estimator is operated, which computes values of its state variables based on time-tagged measurement data from the respective devices, wherein the time-tagged measurement data represents a motion of a first device measured, on the one hand, by the first device and, on the other hand, by a second device. The method does not necessarily depend on good GNSS coverage. Systems and devices for carrying the method, or a part thereof, are also disclosed.
Claims19
Method, carried out by a system comprising a first device, hereinafter referred to as “device A”, and a second device, hereinafter referred to as “device B”, wherein
- device A and device B are moving, at least for a period of time, with respect to each other;
- a first clock, hereinafter referred to as “clock A”, runs on device A;
- a second clock, hereinafter referred to as “clock B”, runs on device B;
- and
- device A comprises a motion sensor;
- the method comprising:
- measuring, using the motion sensor of device A, a motion of device A, wherein data indicative of the motion of device A measured using the motion sensor of device A is hereinafter referred to as “measurement data A”, and measurement data A is time-tagged using clock A;
- measuring, by device B, a motion of at least one point of device A with respect to device B, wherein data indicative of the motion of the at least one point of device A with respect to device B as measured by device B [is hereinafter referred to as “measurement data B”, and measurement data B is time-tagged using clock B];
- operating an estimation process, hereinafter referred to as “estimator”, wherein
- the estimator uses state variables comprising:
- at least one state variable representing an estimated offset between clock A and clock B or from which the estimated offset can be derived, and
- at least one position-related state variable;
- and
- the estimator computes values of its state variables based on:
- the time-tagged measurement data A, and
- the time-tagged measurement data B;
- and
- outputting, by the estimator, at least one of:
- the estimated offset between clock A and clock B;
- and
- at least one estimated motion state of device A.
Method, carried out by a device or a set of devices, for estimating an offset between a first clock, hereinafter referred to as “clock A”, and a second clock, hereinafter referred to as “clock B”, wherein
- clock A runs on a first device, hereinafter referred to as “device A”;
- clock B runs on a second device, hereinafter referred to as “device B”;
- device A and device B are moving, at least for a period of time, with respect to each other;
- and
- device A comprises a motion sensor;
- the method comprising:
- obtaining data indicative of a motion of device A measured using the motion sensor of device A, wherein the data is hereinafter referred to as “measurement data A”, and measurement data A is time-tagged using clock A;
- obtaining data indicative of a motion of the at least one point of device A with respect to device B as measured by device B, wherein the data is hereinafter referred to as “measurement data B”, and measurement data B is time-tagged using clock B;
- operating an estimation process, hereinafter referred to as “estimator”, wherein
- the estimator uses state variables comprising:
- at least one state variable representing an estimated offset between clock A and clock B or from which the estimated offset can be derived, and
- at least one position-related state variable;
- and
- the estimator computes values of its state variables based on:
- the time-tagged measurement data A, and
- the time-tagged measurement data B;
- and
- outputting, by the estimator, at least one of:
- the estimated offset between clock A and clock B;
- and
- at least one estimated motion state of device A.
Device or set of devices for estimating an offset between a first clock, hereinafter referred to as “clock A”, and a second clock, hereinafter referred to as “clock B”, wherein
- clock A is configured for running on a first device, hereinafter referred to as “device A”;
- clock B is configured for running on a second device, hereinafter referred to as “device B”;
- device A and device B are configured for moving, at least for a period of time, with respect to each other;
- and
- device A comprises a motion sensor;
- the device, or the set of devices, being configured for:
- obtaining data indicative of a motion of device A measured using the motion sensor of device A, wherein the data is hereinafter referred to as “measurement data A”, and measurement data A is time-tagged using clock A;
- obtaining data indicative of a motion of the at least one point of device A with respect to device B as measured by device B, wherein the data is hereinafter referred to as “measurement data B”, and measurement data B is time-tagged using clock B;
- operating an estimation process, hereinafter referred to as “estimator”, wherein
- the estimator uses state variables comprising:
- at least one state variable representing an estimated offset between clock A and clock B or from which the estimated offset can be derived, and
- at least one position-related state variable;
- and
- the estimator computes values of its state variables based on:
- the time-tagged measurement data A, and
- the time-tagged measurement data B;
- and
- outputting, by the estimator, at least one of:
- the estimated offset between clock A and clock B;
- and
- at least one estimated motion state of device A.
Dependencies are inferred from the claim text.