Force measuring system having several force-measuring cells and a circuit calculating a total signal

• US 20050121236A1
• Filed: 11/12/2004
• Published: 06/09/2005
• Est. Priority Date: 05/15/2002
• Status: Active Grant

• Current Assignee: Sartorius Lab Instruments GmbH & Co. KG (Sartorius AG)
• Original Assignee: Sartorius AG
• Inventors: Oldendorf, Christian, Lauke, Juergen, Schink, Thomas
• Granted Patent: US 7,211,748 B2
• Time in Patent Office: Days
• US Class Current: 177/144
• CPC Class Codes: G01G 19/4142 for controlling activation of safety devices, e.g. airbag systems electrical circuits for triggering safety arrangements in case of vehicle accidents B60R21/015
• CPC Class Codes: G01G 23/3707 using a microprocessor
• CPC Class Codes: G01G 3/147 involving digital counting

Abstract

A force measuring system with at least two load cells (1, 2), which detect and convert partial forces of the force to be measured into a digital output signal, and with an electronic circuit (5), which calculates a total signal from the output signals of the individual load cells according to the amount of the force to be measured and transmits this total signal to another electronic unit (3) for further processing or data output. The electronic circuit (5) is integrated into at least one load cell (2), whereby the hardware requirements are minimized while detection of the measured values is clearly separated from further processing of the measured values. Advantageously the electronic circuit (5) can be integrated into each load cell (2).

Claims

1. A system for measuring a force, comprising:

at least two load cells, each detecting a partial force of the force to be measured and outputing a corresponding digital output signal,

an electronic unit; and

an electronic circuit that, based on the output signals of the load cells, calculates a total signal corresponding to a magnitude of the force to be measured and transmits the total signal to the electronic unit for further processing or data output;

wherein the electronic circuit is integrated into one of the load cells.

2. The system as claimed in claim 1, wherein an electronic circuit is integrated into each load cell.

3. The system as claimed in claim 1, wherein the load cells are interconnected by a bus system.

4. The system as claimed in claim 3, wherein the electronic unit is connected to the bus system.

5. The system as claimed in claim 4, further comprising at least one additional electronic circuit, wherein each of the electronic circuits is integrated into a different one of the load cells, and wherein a determination as to which of the electronic circuits calculates the total signal and transmits the total signal to the electronic unit is made by connector coding, selector switch or parameterization in a read-only memory.

6. The system as claimed in claim 4, further comprising at least one additional electronic circuit, wherein each of the electronic circuits is integrated into a different one of the load cells, wherein at least two of the electronic circuits each calculates a respective total signal and transmits that the respective total signal to the electronic unit, wherein the transmitted total signals are compared, and wherein an error signal is output if the transmitted total signals do not match.

7. The system as claimed in claim 4, further comprising at least two additional electronic circuits, wherein each of the electronic circuits is integrated into a different one of the load cells, wherein each of the electronic circuits calculates a respective total signal and forwards that the respective total signal to the electronic unit, wherein the three forwarded total signals are compared, and wherein an output is generated by the electronic unit only if at least two of the respective total signals match.

8. The system as claimed in claim 1, wherein at least one of the load cells has an additional connection for the electronic unit.

9. The system as claimed in claim 1, comprising at least three load cells and a common weighing platform, and wherein the common weighing platform is supported by the at least three load cells.

10. The system as claimed in claim 9, wherein the electronic circuit that calculates the total signal and transmits the total signal to the electronic unit calculates additional parameters.

11. The system as claimed in claim 10, wherein the additional parameters include the position of the center of gravity or the point of application of the force to be measured.

12. The system as claimed in claim 1, comprising at least three load cells and a seat, and wherein the at least three load cells determine the load on the seat.

13. The system as claimed in claim 12, wherein the electronic circuit that calculates the total signal and transmits the total signal to the electronic unit calculates additional parameters.

14. The system as claimed in claim 13, wherein the additional parameters include the position of the center of gravity or the point of application of the force to be measured.

15. A system for measuring a force, comprising:

a first load cell that detects a first part of the force to be measured and outputs a corresponding first load cell signal;

a second load cell that detects a second part of the force to be measured and outputs a corresponding second load cell signal;

a first electronic circuit; and

a separate electronic unit downstream of the first and second load cells; and

wherein, based on the first load cell signal and the second load cell signal, the first electronic circuit calculates a first total signal corresponding to a magnitude of the force to be measured and transmits the first total signal to the electronic unit for further processing or data output; and

wherein the first electronic circuit is integrated into the first load cell.

16. The system as claimed in claim 15, further comprising a second electronic circuit integrated into the second load cell.

17. The system as claimed in claim 15, wherein the first and second load cells are interconnected by a bus system.

18. The system as claimed in claim 17, wherein the electronic unit is connected to the bus system.

19. The system as claimed in claim 15, further comprising a second electronic circuit integrated into the second load cell;

and wherein a determination that the first electronic circuit calculates the first total signal and transmits the first total signal to the electronic unit is made by connector coding, selector switch or parameterization in a read-only memory of at least one of the first and second load cells.

20. The system as claimed in claim 15, further comprising a second electronic circuit integrated into the second load cell;

wherein the second electronic circuit calculates a second total signal corresponding to a magnitude of the force to be measured and transmits that second total signal to the electronic unit; and

wherein the transmitted first and second total signals are compared and an error signal is output if the transmitted total signals do not match.

21. The system as claimed in claim 15, further comprising:

a second electronic circuit integrated into the second load cell,

a third load cell that detects a third part of the force to be measured and outputs a corresponding third load cell signal; and

a third electronic circuit integrated into the third load cell;

wherein the second electronic circuit calculates a second total signal corresponding to a magnitude of the force to be measured and transmits that second total signal to the electronic unit;

wherein the third electronic circuit calculates a third total signal corresponding to a magnitude of the force to be measured and transmits that third total signal to the electronic unit; and

wherein, the first through third total signals are compared and at least one of the first through third total signals is output only if at least two of the total signals match.

22. The system as claimed in claim 21, wherein, the comparison of the first through third total signals is made before any of the first through third total signal are transmitted to the electronic unit.

23. The system as claimed in claim 15, wherein at least one of the first and second load cells has a separate connection to the electronic unit.

24. The system as claimed in claim 15, further comprising a third load cell that detects a third part of the force to be measured and outputs a corresponding third load cell signal, and

a common weighing platform, and

wherein the common weighing platform is supported by the three load cells.

25. The system as claimed in claim 15, further comprising a motor vehicle seat supported at least in part by the first and second load cells, and wherein the force to be measured is a weight of a person seated in the motor vehicle seat.

26. A method for measuring a force, comprising the steps of:

detecting a first part of the force to be measured with a first load cell and outputting a corresponding first load cell signal;

detecting a second part of the force to be measured with a second load cell and outputting a corresponding second load cell signal;

using electronic circuitry integrated in the first load cell to calculate, based on the first load cell signal and the second load cell signal, a first total signal corresponding to a magnitude of the force to be measured and transmitting the first total signal to an electronic unit separate from the first and second load cells for further processing or data output.

27. The method according to claim 26, wherein the force to be measured is the weight of a person on a motor vehicle seat.