Systems and methods of tracking position and speed in GNSS applications
View Patent ↗Systems and methods of tracking a mobile subject based on Global Navigation Satellite Systems (GNSS) data, including a boundary test unit to evaluate a boundary violation according to the current actionable position and current actionable speed of the mobile subject relative to a predetermined boundary, wherein the current actionable position is a sum of a prior actionable position and a product of a degraded position difference and a position tracking coefficient, and a current actionable speed is a function of a prior actionable speed and a degraded speed estimate.
1. An apparatus to track a mobile subject based on Global Navigation Satellite Systems (GNSS) data, comprising:
a motion detector to detect motion of the mobile subject independently of the GNSS data;
a boundary determining unit to define a predetermined boundary area relative to the mobile subject;
an actionable position and speed determination unit configured to receive the GNSS data and determine a current actionable position and a current actionable speed of the mobile subject,
wherein the actionable position and speed determination unit is configured to calculate the current actionable position according to a sum of a prior actionable position and a product of a degraded position difference and a position tracking coefficient, the degraded position difference being a product of a position degrade coefficient and a difference between a current GNSS position and the prior actionable position, the position degrade coefficient being a function of current GNSS position solution metrics, current GNSS signal metrics, prior GNSS position solution metrics, and prior GNSS signal metrics, and the position tracking coefficient being a function of the actionable speed and a detected motion from the motion detector, and
wherein the actionable position and speed determination unit is configured to calculate the current actionable speed of the mobile subject according to a function of a prior actionable speed and a degraded speed estimate, the degraded speed estimate being a product of a speed estimate and a speed degrade coefficient, the speed estimate being a function of the prior speed estimate and a GNSS speed estimate, the speed degrade coefficient being a function of current GNSS speed solution metrics, current GNSS signal metrics, prior GNSS speed solution metrics and prior GNSS signal metrics; and
a boundary test unit configured to evaluate a boundary violation according to the current actionable position and current actionable speed of the mobile subject relative to the predetermined boundary.
2. The apparatus of claim 1 , wherein the position degrade coefficient is lower bounded by whether or not the prior actionable position and speed resulted in a boundary violation.
3. The apparatus of claim 1 , wherein the speed degrade coefficient is lower bounded by whether or not the prior actionable position and speed resulted in a boundary violation.
4. The apparatus of claim 1 , wherein the current actionable speed is further a function of GNSS solution metrics.
5. The apparatus of claim 1 , wherein the current actionable speed is further a function of whether or not the prior actionable position and speed resulted in a boundary violation.
6. The apparatus of claim 1 , wherein the GNSS solution metrics include an horizontal dilution of precision, estimated horizontal position error, estimated speed error, the horizontal dilution of precision times the estimated horizontal position error, the horizontal dilution of precision times the estimated speed error, or any combination thereof.
7. The apparatus of claim 1 , wherein the GNSS signal metrics include a quantity representative of the aggregate observable GNSS signal to noise ratio and/or a quantity representative of the aggregate eligible GNSS signal to noise ratio, observable indicating all GNSS signals used to determine the GNSS position and speed, and eligible indicating all decodable GNSS signals emanating from satellites above a predetermined elevation threshold.
8. The apparatus of claim 1 , wherein said motion detector is a micro electro-mechanical systems (MEMS) device.
9. The apparatus of claim 1 , wherein said motion detector is an omnidirectional vibration sensor.
10. The apparatus of claim 1 , wherein a predetermined location within a containment area is used as an initial start location of the mobile subject.
11. The apparatus of claim 1 , wherein the prior actionable position and speed are maintained in response to the motion detector detecting no motion of the mobile subject.
12. The apparatus of claim 1 , wherein the GNSS data includes GNSS PVT (position, velocity, time) signals, pseudo-range error data, time assist data, ephemeris assist data, or any combination thereof.
13. The apparatus of claim 1 , wherein the mobile subject is a human or animal.
14. The apparatus of claim 1 , wherein the apparatus is attached to or worn by the mobile subject.
15. A method of tracking a mobile subject based on Global Navigation Satellite Systems (GNSS) data, the method comprising:
detecting motion of the mobile subject independently of the GNSS data with a motion detector;
defining a predetermined boundary area relative to the mobile subject with a boundary determining unit;
receiving the GNSS data at an actionable position and speed determination unit, and determining an actionable position and an actionable speed of the mobile subject,
wherein the actionable position and speed determination unit is configured to calculate the current actionable position according to a sum of a prior actionable position and a product of a degraded position difference and a position tracking coefficient, the degraded position difference being a product of a position degrade coefficient and a difference between a current GNSS position and the prior actionable position, the position degrade coefficient being a function of current GNSS position solution metrics, current GNSS signal metrics, prior GNSS position solution metrics, and prior GNSS signal metrics, and the position tracking coefficient being a function of the actionable speed and a detected motion from the motion detector, and
wherein the current actionable position and speed determination unit is configured to calculate the current actionable speed of the mobile subject according to a function of a prior actionable speed and a degraded speed estimate, the degraded speed estimate being a product of a speed estimate and a speed degrade coefficient, the speed estimate being a function of the prior speed estimate and a GNSS speed estimate, the speed degrade coefficient being a function of current GNSS speed solution metrics, current GNSS signal metrics, prior GNSS speed solution metrics, and prior GNSS signal metrics; and
evaluating a boundary violation according to the current actionable position and current actionable speed of the mobile subject relative to the predetermined boundary.
16. The method of claim 15 , wherein the GNSS solution metrics include an horizontal dilution of precision, estimated horizontal position error, estimated speed error, the horizontal dilution of precision times the estimated horizontal position error, the horizontal dilution of precision times the estimated speed error, or any combination thereof.
17. The method of claim 15 , wherein the GNSS signal metrics include a quantity representative of the aggregate observable GNSS signal to noise ratio and/or a quantity representative of the aggregate eligible GNSS signal to noise ratio, observable indicating all GNSS signals used to determine the GNSS position and speed, and eligible indicating all decodable GNSS signals emanating from satellites above a predetermined elevation threshold.
18. The method of claim 15 , wherein a predetermined location within a containment area is used as an initial start location of the mobile subject.
19. The method of claim 15 , wherein the prior actionable position and speed are maintained in response to detecting no motion of the mobile subject.
20. The method of claim 15 , wherein the GNSS data includes GNSS PVT (position, velocity, time) signals, pseudo-range error data, time assist data, ephemeris assist data, or any combination thereof.
21. The method of claim 15 , wherein the mobile subject is a human or animal.
22. A non-transitory computer readable storage medium having recorded thereon a program to cause a computer to perform a method of tracking a mobile subject to detect a boundary violation based on Global Navigation Satellite Systems (GNSS) data, the method comprising:
detecting motion of the mobile subject independently of the GNSS data with a motion detector;
defining a predetermined boundary area relative to the mobile subject with a boundary determining unit;
receiving the GNSS data at an actionable position and speed determination unit, and determining an actionable position and an actionable speed of the mobile subject,
wherein the actionable position and speed determination unit is configured to calculate the current actionable position according to a sum of a prior actionable position and a product of a degraded position difference and a position tracking coefficient, the degraded position difference being a product of a position degrade coefficient and a difference between a current GNSS position and the prior actionable position, the position degrade coefficient being a function of current GNSS position solution metrics, current GNSS signal metrics, prior GNSS position solution metrics, and prior GNSS signal metrics, and the position tracking coefficient being a function of the actionable speed and a detected motion from the motion detector, and
wherein the actionable position and speed determination unit is configured to calculate the current actionable speed of the mobile subject according to a function of a prior actionable speed and a degraded speed estimate, the degraded speed estimate being a product of a speed estimate and a speed degrade coefficient, the speed estimate being a function of the prior speed estimate and a GNSS speed estimate, the speed degrade coefficient being a function of current GNSS speed solution metrics, current GNSS signal metrics, prior GNSS speed solution metrics, and prior GNSS signal metrics; and
evaluating a boundary violation according to the current actionable position and current actionable speed of the mobile subject relative to the predetermined boundary.
23. An apparatus to track a mobile subject based on Global Navigation Satellite Systems (GNSS) data, comprising:
an actionable position and speed determination unit configured to receive GNSS data and determine a current actionable position and a current actionable speed of the mobile subject,
wherein the actionable position and speed determination unit is configured to calculate the current actionable position by processing current GNSS position data according to one or more estimate parameters derived from one or more previous actionable positions previously calculated by the actionable position and speed determination unit, and
wherein the actionable position and speed determination unit is configured to calculate the current actionable speed by processing current GNSS speed data according to one or more estimate parameters derived from one or more previous actionable speeds previously calculated by the actionable position and speed determination unit.
24. The apparatus of claim 23 , further comprising a boundary test unit to evaluate a boundary violation according to the current actionable position and current actionable speed of the mobile subject relative to a predetermined boundary.