Load cell having strain gauges of arbitrary location
View Patent ↗A load cell utilizes a plurality of strain gauges mounted upon the load cell body such that there are six independent load-strain relations. Load is determined by applying the inverse of a load-strain sensitivity matrix to a measured strain vector. The sensitivity matrix is determined by performing a multivariate regression technique on a set of known loads correlated to the resulting strains. Temperature compensation is achieved by configuring the strain gauges as co-located orthogonal pairs.
1. A load cell comprising:
a body adapted for receiving a load;
strain gauges mounted upon the body such that there are at least six independent load-strain relations, each gauge producing an output, each gauge mounted at an arbitrary location on the body; and
processing means in communication with the strain gauge outputs, the processing means including a computer readable medium tangibly embodying at least one set of instructions to decouple load-strain relations.
2. The load cell of claim 1 wherein the computer readable medium tangibly embodying at least one set of instructions to decouple load-strain relations comprises a computer readable medium tangibly embodying at least one set of instructions to generate a decoupling matrix.
3. The load cell of claim 2 wherein the computer readable medium tangibly embodying at least one set of instructions to generate a decoupling matrix comprises a computer readable medium tangibly embodying at least one set of instructions to generate a coefficient matrix by performing a multivariate regression technique on a set of applied loads correlated to the resulting strains.
4. The load cell of claim 3 wherein the computer readable medium tangibly embodying at least one set of instructions to generate a coefficient matrix by performing a multivariate regression technique on a set of applied loads correlated to the resulting strains further comprises a computer readable medium tangibly embodying at least one set of instructions to apply the inverse of the coefficient matrix to a measured strain vector to determine load components.
5. The load cell of claim 1 wherein the strain gauges are configured to achieve temperature compensation.
6. The load cell of claim 5 wherein the strain gauges comprise co-located orthogonal pairs of strain gauges.
7. A method of designing a load cell, the method comprising:
providing a body adapted for receiving a load;
mounting a plurality of strain gauges upon the body such that there are at least six independent load-strain relations, each of the plurality of strain gauges mounted at an arbitrary location on the body;
applying a known load to the body; and
calibrating the load cell by gathering load-strain data and developing a sensitivity matrix for the load cell.
8. The method of claim 7 further comprising compensating for temperature.
9. The method of claim 8 wherein compensating for temperature comprises co-locating orthogonal pairs of strain gauges.
10. A method of determining load using a load cell, the method comprising:
providing a body adapted for receiving a load;
mounting strain gauges upon the body such that there are at least six independent load-strain relations, each gauge mounted at an arbitrary location on the body;
applying a load to the load cell; and
mathematically decoupling load-strain relations.
11. The method of claim 10 wherein mathematically decoupling load-strain relations comprises applying the inverse of a coefficient matrix to a measured strain vector to determine load components.
12. The method of claim 11 wherein the coefficient matrix comprises a coefficient matrix generated by performing a multivariate regression technique on load-strain relations.
13. The method of claim 10 further comprising compensating for temperature.
14. The method of claim 13 wherein compensating for temperature comprises co-locating orthogonal pairs of strain gauges.
15. A computer readable medium tangibly embodying at least one set of instructions to perform the steps of:
gathering load-strain data from a load cell, the load cell comprising a body adapted for receiving a load, strain gauges mounted upon the body such that there are at least six independent load-strain relations, each gauge producing an output, each gauge mounted at an arbitrary location on the body; and
developing a load-strain sensitivity matrix for the load cell.
16. The computer readable medium of claim 15 further comprising at least one set of instructions to perform the step of determining a load applied to the load cell by applying the inverse of the load-strain sensitivity matrix to a measured strain vector.
17. The computer readable medium of claim 15 wherein the load-strain sensitivity matrix comprises a coefficient matrix generated by performing a multivariate regression technique on a set of applied loads correlated to resulting strains.