Method for adjusting a resistance-gage force transducer and an adjusted force transducer thus obtained
First Claim
1. A method for adjusting a resistance-gage force transducer (resistance gages R1, R2, R3, R4) comprising a resilient bar (1) attached at one end to a stationary support (2) and subjected at the other end to the force (P) to be measured, said bar (1) being adapted to carry resistance gages (R1, . . . R4) electrically connected to each other so as to form a measuring bridge for delivering an electrical signal which is a function of the force applied to said other end of the bar, said transducer being adjustable by means of said method in such a manner as to ensure that said electrical signal is proportional to the applied force and insensitive to the torsional and flexural couples generated by the displacements of the point of application of the force (P) to be measured, said method being distinguished by the following steps:
- A. Determination of the initial characteristics of the transducer,B. Computation of the relative errors of the transducer arising from a displacement of the applied force (P) as a function of the angle θ
formed between the resistance gages (R1, . . . R4) and the longitudinal direction (Ox) of the bar,C. Cancellation of these errors by making modifications in one or a number of resistance gages in order to produce a modification of the angle θ
aforesaid.
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Accused Products
Abstract
A force transducer comprises a resilient bar (1) which carries a measuring bridge formed by resistance gages (R1, . . . R4). One end of the bar is attached to a stationary support (2) and the other end is subjected to a force (P) to be measured. A method for ensuring that the signal delivered by the measuring bridge is proportional to the applied force and insensitive to parasitic couples consists in determining the initial characteristics of the transducer, in computing the relative errors arising from a displacement of the force (P) applied as a function of the angle made between the resistance gages (R1, . . . R4) and the longitudinal direction (Ox) of the bar (1) and in cancelling these errors by making changes in one or a number of gages in order to modify the angle aforesaid.
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Citations
11 Claims
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1. A method for adjusting a resistance-gage force transducer (resistance gages R1, R2, R3, R4) comprising a resilient bar (1) attached at one end to a stationary support (2) and subjected at the other end to the force (P) to be measured, said bar (1) being adapted to carry resistance gages (R1, . . . R4) electrically connected to each other so as to form a measuring bridge for delivering an electrical signal which is a function of the force applied to said other end of the bar, said transducer being adjustable by means of said method in such a manner as to ensure that said electrical signal is proportional to the applied force and insensitive to the torsional and flexural couples generated by the displacements of the point of application of the force (P) to be measured, said method being distinguished by the following steps:
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A. Determination of the initial characteristics of the transducer, B. Computation of the relative errors of the transducer arising from a displacement of the applied force (P) as a function of the angle θ
formed between the resistance gages (R1, . . . R4) and the longitudinal direction (Ox) of the bar,C. Cancellation of these errors by making modifications in one or a number of resistance gages in order to produce a modification of the angle θ
aforesaid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A resistance-gage force transducer (resistance gages R1, . . . R4) comprising a resilient bar (1) such that one end of said bar is intended to be attached to a stationary support (2) and the other end is subjected to the force (P) to be measured, said bar (1) being adapted to carry resistance gages (R1, . . . R4) electrically connected to each other so as to form a measuring bridge for delivering an electrical signal which is a function of the force (P) applied to said other end of the bar, said transducer being so adjusted as to ensure that the signal is proportional to the applied force (P) and insensitive to the torsional and flexural couples generated by the displacements of the point of application of the force to be measured, wherein the angle θ
- formed between one or a plurality of resistance gages (R1, . . . R4) and the longitudinal direction (Ox) of the bar (1) satisfies the following relations;
space="preserve" listing-type="equation">e.sub.x =e.sub.x.sbsb.o +1/C.sub.x Σ
cos 2θ
=0
space="preserve" listing-type="equation">e.sub.z =e.sub.z.sbsb.o +1/C.sub.z Σ
sin 2θ
=0where ex and ez are the errors due to a displacement of the force (P) applied respectively along the axis (Ox) of the bar (1) and along an axis (Oz) perpendicular to said axis of the bar and to the applied force, ex.sbsb.o and ez.sbsb.o are the initial errors determined during a step which involves initial characterization of the transducer, Cx and Cz are known constants established by design and by the conditions of said initial characterization. - View Dependent Claims (10, 11)
- formed between one or a plurality of resistance gages (R1, . . . R4) and the longitudinal direction (Ox) of the bar (1) satisfies the following relations;
Specification