Skid and Roll Tracking System

• US 20180120428A1
• Filed: 10/31/2016
• Published: 05/03/2018
• Est. Priority Date: 10/31/2016
• Status: Active Grant

• Current Assignee: Trackman A/S
• Original Assignee: Trackman A/S
• Inventors: TUXEN, Fredrik, BRASCH, Jesper
• Granted Patent: US 10,444,339 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 13/58 Velocity or trajectory determination systems; Sense-of-movement determination systems
• CPC Class Codes: G01S 13/583 using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets
• CPC Class Codes: G01S 13/584 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 13/723 by using numerical data
• CPC Class Codes: G01S 7/35 Details of non-pulse systems

Abstract

A system for tracking an object includes a first tracking device aimed so that a first field of view of the first tracking device covers at least a portion of a target volume into which an object is to be launched from a launch location and a processor receiving data from the tracking device and identifying from the data the velocity of the object over time, the processor identifying, based on changes in the velocity of the object over time, a first portion of a path of the object during which the object was in one of a bouncing state and a sliding state.

Claims

1. A system for tracking the velocity an object, comprising:

a first tracking device aimed so that a first field of view of the first tracking device covers at least a portion of a target volume into which an object is to be launched from a launch location; and

a processor receiving data from the tracking device and identifying from the data the velocity of the object over time, the processor identifying, based on changes in the velocity of the object over time, a portion of a path of the object during which the object was in one of a bouncing state, a sliding state or a rolling state.

2. The system of claim 1, wherein for each of a plurality of time frames, the processor receives from the first tracking device a signal and calculates from this signal object data including position and velocity values for the object.

3. The system of claim 2, wherein the processor determines a velocity as a function of time of the object.

4. The system of claim 3, wherein the processor separates the velocity curve into a plurality of segments, each segment being a portion of the velocity which is continuous and has a continuous derivative.

5. The system of claim 4, wherein each of the plurality of segments is identified as one of a bouncing, sliding and rolling state based on the slope of the velocity of the segment.

6. The system of claim 5, wherein, when the slope of the velocity of the segment is less than a first predetermined threshold and the previous segment was not a roll state, the object is determined to be in a sliding state.

7. The system of claim 5, wherein, when the slope of the velocity of segment is less than a second predetermined threshold, the object is determined to be in a rolling state.

8. The system of claim 5, wherein, when the slope of the velocity of the segment is greater than the predetermined roll threshold and the distance traveled during the segment divided by the total distance traveled is greater than a third predetermined threshold, the object is determined to be in a bouncing state.

9. The system of claim 5, wherein a distance the object has traveled in the one of the bouncing, sliding or rolling state is determined by calculating the area under the respective bouncing, sliding and rolling segment(s) of the velocity vs. time curve.

10. The system of claim 3, wherein the processor detects discontinuities in the velocity and a derivative thereof and identifies these discontinuities as time separators—

between adjacent segments.

11. The system of claim 10, wherein the processor detects discontinuities at locations where a difference in one of velocity and acceleration between adjacent time intervals is greater than a set threshold.

12. The system of claim 1, wherein the tracking device is a continuous wave Doppler radar.

13. The system of claim 5, wherein the slope of the surface over which the object moves in each segment is used to compensate the slope of the velocity, where the slope of the surface is determined from the measured height of the object over the distance traveled.

14. The system of claim 12, wherein a first radar transmit frequency is between 10 and 125 GHz.

16. The system of claim 1, further comprising a second tracking device aimed so that a second field of view of the second tracking device covers at least a portion of the target volume including a portion of the target volume outside the first field of view.

17. A method for tracking the movement of an object, comprising:

positioning a first tracking device aimed so that a first field of view of the first tracking device covers at least a portion of a target volume into which an object is to be launched from a launch location;

determining, using a processor, based on data received from the first tracking device, a velocity value of the object at each of a plurality of time frames to form a velocity curve as a function of the time;

separating the velocity curve into a plurality of segments, each segment being a portion of the curve in which all changes between adjacent time frames in one of velocity and a derivative of velocity are less than a threshold value; and

identifying each segment as one of a bouncing, sliding and rolling state based on the slope of the velocity of the segment.

18. The method of claim 17, further comprising:

determining the distance the object traveled in one of a bounce or slide state by calculating the area under the respective bounce or slide velocity vs. time segment curve.

19. The method of claim 17, wherein the processor detects discontinuities in the velocity and a derivative thereof to identify end points for each segment.

20. The method of claim 17, wherein the first radar transmit frequency is between 10 and 125 GHz.