Context acquisition based on load sensing

• US 7,434,459 B2
• Filed: 09/26/2003
• Issued: 10/14/2008
• Est. Priority Date: 09/30/2002
• Status: Active Grant

• Current Assignee: SAP SE
• Original Assignee: SAP AG (SAP SE)
• Inventors: Kubach, Uwe, Friday, Adrian, Strohbach, Martin, Laerhoven, Kristof Van, Gellersen, Hans-W., Schmidt, Albrecht
• Primary Examiner(s): BARNES-BULLOCK, CRYSTAL JOY
• Application Number:
  US10/670,781
• Publication Number:
  US 20040148089A1
• Time in Patent Office: 1,845 Days
• Field of Search: 700/56, 700/57, 700/58, 700/60, 700/61, 700/62, 700/64, 700/65, 700/258, 700/301, 700/302, 700/305, 702/47, 702/92, 702/93, 702/104, 702/188, 702/128, 702/129, 702/138, 702/139, 702/173, 73/11.5, 737/45, 737/54, 737/06, 737/15, 737/77, 731/72, 738/623.25, 738/620.42, 738/620.45, 738/620.46, 340/426.24, 340/856.3, 340/995.28, 340/540, 340665-667, 324/207.11, 324/207.12, 324/207.13
• US Class Current: 73/172
• 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,

wherein computing a center of force comprises;

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

computing the center of force of the object on the surface;

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.

2. 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.

3. The method of claim 1 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.

4. 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.

5. The method of claim 4 comprising:

identifying the object as a person; and

tracking the position of the person.

6. The method of claim 4 comprising:

identifying the first and second objects as people; and

tracking a center of activity of the people.

7. 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.

8. The method of claim 7 comprising compensating for the force applied by the surface to the load cells.

9. A method comprising:

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

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

computing an average force on the surface during each of the time intervals;

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.

10. The method of claim 9 comprising computing a variability in the force on the surface during each of the time intervals.

11. The method of claim 9 comprising comparing a difference between the first average weight and the second average weight to an average weight threshold.

12. The method of claim 9 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.

13. 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;

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

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,

wherein computing a 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.

14. 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;

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

sensing the force information at a later period of time;

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

identifying the object as a person;

tracking the position of the person;

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.