Estimating positions of a device and at least one target in an environment
A method/system for estimating a state of a device and at least one target in an environment. The process involves computing a state vector using an error state form of the position of the device in a local coordinate reference frame.
1. A method of estimating a position of a device (and at least one target in an environment, the method including computing a state vector defined by:
a vector representing a position of the device with respect to an origin of a global coordinate reference frame;
a vector representing an estimated position of the at least one target with respect to an origin of an estimated local coordinate reference frame; and
an error state form based on a difference between the origin of the estimated local coordinate reference frame and an origin of a correction-free local coordinate reference frame in which a position of the device is assumed to be error-free,
wherein the state vector is based on a correction-free local frame simultaneous localization and mapping (SLAM) model, and wherein computing the state vector includes deterministically deriving the error-free position of the device.
2. A method according to claim 1 , wherein the position of the device in the correction-free local coordinate frame is formally independent of estimated quantities used in the state vector computation.
3. A method according to claim 1 , wherein if the origin of the global coordinate reference frame is not co-incident with the origin of the estimated local coordinate frame then the vector state is further defined by a vector describing relative positions of these origins.
4. A method of estimating a position of a device and at least one target in an environment, the method including computing a state vector defined by:
a vector representing a position of the device with respect to an origin of an estimated local coordinate frame associated with the device;
a vector representing an estimated position of the at least one target with respect to an origin of the estimated local coordinate reference frame; and
an error state form based on a difference between the origin of the estimated local coordinate reference frame and an origin of a correction-free local coordinate reference frame in which a position of the device is assumed to be error-free,
wherein the state vector is based on a correction-free local frame simultaneous localization and mapping (SLAM) model, and wherein computing the state vector includes deterministically deriving the error-free position of the device.
5. A computer program product comprising a tangible computer readable medium, having thereon computer program code, when the program code is loaded, to make the computer execute a method of estimating a state of a device and at least one target in an environment according to claim 1 .
6. Apparatus configured to estimate a position of a device and at least one target in an environment, the apparatus including a device configured to compute a state vector defined by:
a vector representing a position of the device with respect to an origin of a global coordinate reference frame;
a vector representing an estimated position of the at least one target with respect to an origin of an estimated local coordinate reference frame; and
an error state form based on a difference between the origin of the estimated local coordinate reference frame and an origin of a correction-free local coordinate reference frame in which a position of the device is assumed to be error-free,
wherein the state vector is based on a correction-free local frame simultaneous localization and mapping (SLAM) model, and wherein computing the state vector includes deterministically deriving the error-free position of the device.
7. Apparatus according to claim 6 , including at least one sensor for taking measurements relating to a said target in a vicinity of the device.
8. Apparatus according to claim 7 , wherein the at least one sensor is mounted onboard the device.
9. Apparatus according to claim 6 , including:
a device for receiving information relative to the global coordinate reference frame.
10. Apparatus according to claim 9 , wherein the device for receiving global information is configured to receive a GPS locating signal.
11. The apparatus according to claim 6 , in combination with a vehicle.