Context acquisition based on load sensing

• US 20040148089A1
• Filed: 09/26/2003
• Published: 07/29/2004
• Est. Priority Date: 09/30/2002
• Status: Active Grant

• Current Assignee: SAP SE
• Original Assignee: SAP AG (SAP SE)
• Inventors: Van Laerhoven, Kristof, Kubach, Uwe, Friday, Adrian, Strohbach, Martin, Gellersen, Hans-W., Schmidt, Albrecht
• Granted Patent: US 7,434,459 B2
• Time in Patent Office: Days
• US Class Current: 701/124
• CPC Class Codes: G06F 3/0414 using force sensing means to determine a position

Abstract

Methods and systems are described for sensing force information at a plurality of points on a continuous surface, and detecting contextual information about an object on the surface based on the distribution of force on the surface. For example, a plurality of sensors may be included below different points on such a substantially continuous surface, where the sensors are operable to sense force information. Then, a processor connected to the sensors may determine a location of the object relative to the surface, based on the force information from the sensors.

Claims

1. A method comprising:

sensing force information at a plurality of points on a substantially continuous surface, the force information related to an object on the surface;

calculating a distribution of force exerted by the object, relative to the surface, based on the force information; and

determining a location of the object on the surface, based on the distribution of force.

2. The method of claim 1 wherein computing the center of force comprises:

computing a total force applied to the surface by the object; and

computing a center of force of the object on the surface.

3. The method of claim 2 wherein computing the center of force comprises:

determining a first component of the center of force by computing a first quotient of a first sum and a total force applied to the surface by the object, the first sum obtained by summing a first force applied at a first point and a second force applied at a second point; and

determining a second component of the center of pressure, perpendicular to the first component, by computing a second quotient of a second sum and the total force, the second sum being obtained by summing the first force applied at the first point and a third force applied at a third point.

4. The method of claim 1 comprising:

sensing a variation in the force information; and

detecting a change in the location of the object, relative to the surface, based on the variation in the force information.

5. The method of claim 3 comprising:

computing the first and second components of the center of force of the object at a first period of time;

computing the first and second components of the center of force of the object at a second period of time; and

detecting a new location of the object on the surface, based on a change in the first and second components from the first period to the second period.

6. The method of claim 1 comprising:

sensing the force information at a later period of time; and

detecting a second location of a second object on the surface based on the force information.

7. The method of claim 6 wherein computing the center of force comprises:

determining a first component of the center of force by computing a first quotient of a first sum and a total force applied to the surface by the object, the first sum obtained by summing a first force applied at a first point and a second force applied at a second point; and

determining a second component of the center of pressure, perpendicular to the first component, by computing a second quotient of a second sum and the total force, the second sum being obtained by summing the first force applied at the first point and a third force applied at a third point.

8. The method of claim 1 in which sensing force information includes measuring a voltage level at a plurality of load cells, each of the load cells corresponding to each of the plurality of points.

9. The method of claim 8 comprising compensating for the force applied by the surface to the load cells.

10. The method of claim 6 comprising:

identifying the object as a person; and

tracking the position of the person.

11. The method of claim 10 comprising:

identifying the second object as a possession of the person;

detecting an absence of the person on the surface; and

alerting the person that the second object has been left behind.

12. The method of claim 6 comprising:

identifying the first and second objects as people; and

tracking a center of activity of the people.

13. A system comprising:

a plurality of sensors below different points on a substantially continuous surface, the sensors operable to sense force information; and

a processor connected to the sensors and operable to determine contextual information about a first object on the surface, based on the force information.

14. The system of claim 13 comprising a location determination module operable to determine a center of force of the object.

15. The system of claim 14 wherein the location determination module is operable to determine a change in a first location of the object relative to the surface.

16. The system of claim 14 wherein the location determination module is operable to determine a second location of a second object.

17. The system of claim 13 comprising an interaction characterizer module for characterizing an interaction of the object with the surface.

18. The system of claim 17 wherein the interaction characterizer identifies a change in the number of objects on the surface.

19. The system of claim 13 comprising a visualizer that is operable to generate visual representations of the force information.

20. The system of claim 13 wherein the sensors include four load sensors in a rectangular configuration.

21. The system of claim 13 wherein the surface includes a table.

22. The system of claim 13 wherein the surface includes a shelf.

23. The system of claim 13 further comprising a personal computer connected to the processor.

24. The system of claim 13 comprising:

a second plurality of sensors below different points on a second surface;

a second processor connected to the second plurality of sensors; and

a personal computer connected to the processor and second processor.

25. A method comprising:

sampling force information at points on a continuous surface during a plurality of time intervals; and

identifying an interaction between an object and the surface based on the sampled information.

26. The method of claim 25 comprising computing an average force on the surface during each of the time intervals.

27. The method of claim 26 comprising computing a variability in the force on the surface during each of the time intervals.

28. The method of claim 26 comprising:

comparing a first average weight during a starting interval to a second average weight during an ending interval;

determining that a first variability during the starting interval meets or exceeds a variability threshold value;

comparing a second variability during the ending interval to a third variability during an intermediate interval, between the starting and ending intervals; and

identifying a change in a number of objects on the surface, based on the first and second average weights, and the first second, and third variabilities.

29. The method of claim 28 comprising comparing a difference between the first average weight and the second average weight to an average weight threshold.

30. The method of claim 28 comprising:

determining that a difference between the first and second average weights meets or exceeds an average weight threshold;

determining that the third variability meets or exceeds a variability threshold value;

comparing the third variability to the first and second variabilities; and

identifying a change in object position.