Electrical equalization of load element sensitivity

Claim 1

A method of electrically equalizing the strain gauge sensitivity of at least two spaced load elements supporting a platform so that the output signal derived from at least four strain gauges, wherein each load element has secured to it one compression strain gauge and one tension strain gauge, is the same for different positions of a given load on the platform, comprising the steps of: a. providing a strain gauge bridge circuit having four legs including said four strain gauges, the two compression gauges being in opposite legs and the two tension gauges being in the remaining opposite legs; b. applying an input voltage to two opposite corners of the bridge; c. deriving an output signal from the remaining opposite corners of the bridge; d. comparing the output signals from the bridge when a given load is first positioned on said platform off-center closer to one element than the other and then shifted to an alternate position closer to another element than the one element; e. shunting a compression gauge and a tension strain gauge in the leg of said bridge associated with the element exhibiting the most sensitivity with first and second substantially equal resistances of value such that the measured output signals are the same for all positions of said given load on said platforms; and f. varying the value of one of said resistances relative to the other only to the extent necessary to avoid any shifting of the zero point of said output signal as a consequence of differences in the electrical properties of said strain gauges.

Claim 2

A method of electrically equalizing the strain gauge sensitivity of at least two spaced load elements supporting a platform so that the output signal derived from at least four strain gauges, wherein each load element has secured to it one compression strain gauge and one tension strain gauge, is the same for different positions of a given load on the platform, comprising the steps of: a. providing a strain gauge bridge circuit having four legs including said four strain gauges, the two compression gauges being in opposite legs and the two tension gauges being in the remaining opposite legs; b. applying an input voltage to two opposite corners of the bridge; c. deriving an output signal from the remaining opposite corners of the bridge; d. comparing the output signals from the bridge when a given load is first positioned on said platform off-center closer to one element than the other and then shifted to an alternate position closer to another element than the one element; e. shunting a compression gauge and a tension strain gauge in the leg of said bridge associated with the element exhibiting the most sensitivity with first and second substantially equal resistances of value such that the measured output signals are the same for all positions of said given load on said platforms; and f. varying the value of one of said resistances relative to the other only to the extent necessary to avoid any shifting of the zero point of said output signal as a consequence of differences in the electrical properties of said strain gauges.

Claim 3

A method of electrically equalizing the strain gauge sensitivity of four spaced load elements supporting a platform so that the output signal derived from strain gauges, wherein each load element has secured to it one tension strain gauge and one compression strain gauge, is the same for different positions of a given load on the platform, comprising the steps of: a. providing a strain gauge bridge circuit having four legs, two tension strain gauges being connected in series in one leg of said bridge, and two compression strain gauges being connected in series in an adjacent leg of said bridge, the remaining two tension gauges being connected in series in the leg of the bridge opposite to said one leg and the remaining two compression strain gauges being connected in the leg of the bridge opposite said adjacent leg, the tension and compression strain gauges in adjacent legs closer to the particular corner defined by said adjacent legs being secured to the same load element; b. shunting the tension and compression strain gauges nearest the corner of the bridge associated with the most sensitive load element with a first resistance; c. shunting the tension and compression strain gauges nearest an adjacent corner with a second resistance; d. adjusting the value of said first and second resistances such that the measured output signals are the same for all positions of said given load on said platform.

Claim 4

A method of electrically equalizing the strain gauge sensitivity of four spaced load elements supporting a platform so that the output signal derived from strain gauges, wherein each load element has secured to it one tension strain gauge and one compression strain gauge, is the same for different positions of a given load on the platform, comprising the steps of: a. providing a strain gauge bridge circuit having four legs, two tension strain gauges being connected in series in one leg of said bridge, and two compression strain gauges being connected in series in an adjacent leg of said bridge, the remaining two tension gauges being connected in series in the leg of the bridge opposite to said one leg and the remaining two compression strain gauges being connected in the leg of the bridge opposite said adjacent leg, the tension and compression strain gauges in adjacent legs closer to the particular corner defined by said adjacent legs being secured to the same load element; b. shunting the tension and compression strain gauges nearest the corner of the bridge associated with the most sensitive load element with a first resistance; c. shunting the tension and compression strain gauges nearest an adjacent corner with a second resistance; d. adjusting the value of said first and second resistances such that the measured output signals are the same for all positions of said given load on said platform.

Claim 6

An apparatus including a circuit for electrically equalizing strain gauge sensitivity comprising, in combination: a. at least two spaced load elements; b. a platform supported by said load elements; c. at least four strain gauges wherein each load element has secured to it at least one compression strain gauge and one tension strain gauge; d. an electrical strain gauge bridge having four legs, two compression strain gauges being in opposite legs and two tension strain gauges being in the remaining opposite legs; e. first and second substantially equal resistances shunting a compression strain gauge and a tension strain gauge respectively associated with the load element exhibiting the most sensitivity such that the measured output signal from said bridge when a load is applied off-center on said platform closer to one of said load elements than another, is the same as the output signal when the same load is applied off-center on said platform closer to another of said load elements than the one load element, one of said resistances being variable such that its value may be changed relative to the other only to the extent necessary to avoid any shifting of the zero point of said output signals as a consequence of differences in the electrical properties of said srain gauges.

Claim 7

An apparatus including a circuit for electrically equalizing strain gauge sensitivity comprising, in combination: a. at least two spaced load elements; b. a platform supported by said load elements; c. at least four strain gauges wherein each load element has secured to it at least one compression strain gauge and one tension strain gauge; d. an electrical strain gauge bridge having four legs, two compression strain gauges being in opposite legs and two tension strain gauges being in the remaining opposite legs; e. first and second substantially equal resistances shunting a compression strain gauge and a tension strain gauge respectively associated with the load element exhibiting the most sensitivity such that the measured output signal from said bridge when a load is applied off-center on said platform closer to one of said load elements than another, is the same as the output signal when the same load is applied off-center on said platform closer to another of said load elements than the one load element, one of said resistances being variable such that its value may be changed relative to the other only to the extent necessary to avoid any shifting of the zero point of said output signals as a consequence of differences in the electrical properties of said srain gauges.

Claim 9

An apparatus including a circuit for electrically equalizing strain gauge sensitivity comprising, in combination: a. four spaced load elements; b. a platform supported by said load elements; c. eight strain gauges, wherein each load element has secured to it one compression strain gauge and one tension strain gauge; d. an electrical strain gauge bridge having four legs, two tension strain gauges being connected in series in one leg of said bridge and two compression strain gauges being connected in series in an adjacent leg of said bridge, the remaining two tension gauges being connected in series in the leg of the bridge opposite to said one leg and the remaining two compression gauges being connected in series in the remaining leg of the bridge opposite said adjacent leg, the tension and compression strain gauges in adjacent legs closest to the corner defined by said adjacent legs being secured to the same load element; and, e. a first resistance shunting the tension and compression strain gauges nearest the corner of the bridge associated with the most sensitive load element and having a value such that the measured output signal from said bridge when the load is applied off-center on the platform closer to one of the elements than another is the same as the output signal when the same load is applied off-center on the platform closer to another of the load elements than the one load element.

Claim 10

An apparatus including a circuit for electrically equalizing strain gauge sensitivity comprising, in combination: a. four spaced load elements; b. a platform supported by said load elements; c. eight strain gauges, wherein each load element has secured to it one compression strain gauge and one tension strain gauge; d. an electrical strain gauge bridge having four legs, two tension strain gauges being connected in series in one leg of said bridge and two compression strain gauges being connected in series in an adjacent leg of said bridge, the remaining two tension gauges being connected in series in the leg of the bridge opposite to said one leg and the remaining two compression gauges being connected in series in the remaining leg of the bridge opposite said adjacent leg, the tension and compression strain gauges in adjacent legs closest to the corner defined by said adjacent legs being secured to the same load element; and, e. a first resistance shunting the tension and compression strain gauges nearest the corner of the bridge associated with the most sensitive load element and having a value such that the measured output signal from said bridge when the load is applied off-center on the platform closer to one of the elements than another is the same as the output signal when the same load is applied off-center on the platform closer to another of the load elements than the one load element.