DD280820A1

DD280820A1 - SELECTIVE FORCE MEASURING DEVICE

Info

Publication number: DD280820A1
Application number: DD27079184A
Authority: DD
Inventors: Christof Kreuziger
Original assignee: Forsch U Entwicklungs Stelle F
Priority date: 1984-12-14
Filing date: 1984-12-14
Publication date: 1990-07-18

Abstract

Die Erfindung betrifft eine Kraftmesseinrichtung fuer Kraefte, deren Wirkungsrichtung variabel ist und deren Komponente in einer definierten Richtung zu bestimmen ist. Ziel der Erfindung ist es, mit geringem technischen Aufwand die Messgenauigkeit derartiger Kraftmesseinrichtungen zu erhoehen. Erfindungsgemaess besteht das Messglied aus zwei Doppelbiegebalken, die miteinander durch eine der Krafteinleitung dienende Achse verbunden sind, wobei die Achse in der Symmetrieebene durch die Dehnungsmessstreifen tragenden aktiven Verformungskoerper der Doppelbiegebalken liegt und in einer Messschaltung die Summe der an den von den Dehnungsmessstreifen gebildeten Wheatstonschen Widerstandsbruecken entstehenden elektrischen Spannungshuebe erfasst wird. Fig. 2The invention relates to a force measuring device for forces whose direction of action is variable and whose component is to be determined in a defined direction. The aim of the invention is to increase the measurement accuracy of such force measuring devices with little technical effort. According to the invention, the measuring element consists of two double bending beams, which are connected to each other by an axis of force introduction axis, wherein the axis lies in the plane of symmetry by the strain gauge carrying active deformation of the double bending beam and in a measuring circuit, the sum of the Wheatstone resistance bridges formed by the strain gauges electrical Spannungshuebe is detected. Fig. 2

Description

Explanation of the essence of the invention

Der Erfindung liegt die Aufgabe zugrunde, die Kraft so in das mit Dehnungsmeßstreifen bestückte Meßglied einzuleiten, daß die Wirkung der Querkräfte kompensierbar ist und daß nur die Kraftkomponente in der gewünschten Richtung das Meßsignal bestimmt.The invention has for its object to initiate the force in the equipped with strain gauges Meßglied that the effect of the shear forces can be compensated and that only the force component in the desired direction determines the measurement signal.

Erfindungsgemäß wird das dadurch erreicht, daß das Meßglied aus zwei Doppelbiegobalken besteht, die miteinander durch eine der Krafteinleitung dienende Achse derart verbunden sind, daß die Achse in der Symmetrieebene der die Dehnungsmeßstreifen tragenden aktiven Verformungskörper der Doppelbiegebalken liegt und daß in einer Moßschaltung die Summe der an den von den Dehnungsmeßstreifen gebildeten Wheatstonschen Widerstandsbrücken entstehenden elektrischen Spannungshübe erfaßt wird. Hierbei ist die Summe dieser Spannungshübe proportional der Kraftkompcnente des umlaufenden Kraftvektors bezüglich der empfindlichen Achse.According to the invention this is achieved in that the measuring element consists of two double bending bars, which are connected to each other by an axis of force serving axis such that the axis lies in the plane of symmetry of the strain gauges carrying active deformation body of the double bending beam and that in a Moßschaltung the sum of the electrical voltage strokes generated by the strain gauges Wheatstone resistance bridges is detected. Here, the sum of these voltage strokes is proportional to the force component of the rotating force vector with respect to the sensitive axis.

Ausführungsbeispielembodiment

In der Zeichnung ist ein Ausführungsbeispiel der erfindungsgemäßen Kraftmeßeinrichtung an einer Einrichtung zur Ermittlung der vortriebswirksamen Komponente der Dollenkraft von Rennruderbooten dargestellt. Es zeigen:In the drawing, an embodiment of the force measuring device according to the invention is shown on a device for determining the propulsive component of the dollar force of racing rowing boats. Show it:

Fig. 1: eine Draufsicht auf dia KraftmeßeinrichtungFig. 1: a plan view of dia force measuring device

Fig. 2: eine Seitenansicht der KraftmeßeinrichtungFig. 2: a side view of the force measuring device

Fig.3: eine Dolle mit Kraftmeßeinrichtung3: a Dolle with force measuring device

Fig.4: eine Draufsicht auf die Dolle mit Kraftmeßeinrichtung4 shows a plan view of the Dolle with force measuring device

Die Kraftmeßeinrichtung besteht aus dem Meßglied 1, das zwei Doppelbiegebalken 2 enthält. Die Doppelbiegebalken 2 bestehen bekanntermaßen aus aktivem Verforrnungskörper 3 und passivem Vorformungskörper 4. Der aktive Verfr rmungskörper 3 ist symmetrisch mit Dehnungsmeßstreifen 5 beklebt. Beide Doppelbiegebalken 2 sind miteinander durch eine Achse 6 zur Krafteinleitung verbunden, wobei die Längsachse der verbindenden Achse 6 in der Symmetrieebene des die Dehnungsmeßstreifen 5 tragenden aktiven Verformungskörpers 3 angeordnet ist.The force measuring device consists of the measuring element 1, which contains two double bending beam 2. The double bending beam 2 are known to consist of active Verforrnungskörper 3 and passive Vorformungskörper 4. The active Verfr rmungskörper 3 is symmetrically glued with strain gauges 5. Both double bending beams 2 are connected to each other by an axis 6 for introducing force, wherein the longitudinal axis of the connecting axis 6 in the plane of symmetry of the strain gauges 5 supporting active deformation body 3 is arranged.

In einer nicht dargestellten Meßschaitung werden die Summen der an den von den Dehnungsmeßstreifen 5 gebildeten Wheatstonschen Widersiandsbrückan entstehenden elektrischen Spannungshübe orfaßt und ausgewertet. Hierbei ist die Summe dieser Spannungshübe proportional der Kraftkomponente des umlaufenden Kraftvektors bezüglich der empfindlichen Achse 7 der Kraftmeßeinrichtung.In a Meßschaitung, not shown, the sums of the voltage generated by the strain gauges 5 Wheatstone's Wideriandsbrückan resulting electrical voltage strokes orgest and evaluated. Here, the sum of these voltage strokes is proportional to the force component of the revolving force vector with respect to the sensitive axis 7 of the force measuring device.

Bei Anwendung der Kraftmeßeinrichtung gemäß Ausführungsbeispiel an einem Rennruderboot sind die Dollen 8 an Auslegern 9 am Boot gehalten, wobei zwischen Dolle 8 und Ausleger 9 die Kraftmeßeinrichtung angeordnet ist. Hierbei ist die Dollenachse als kraftaufnehmende Achse 6 der Kraftmeßeinrichtung ausgebildet. Jede ander Dolle angreifende Kraft wird über diese Achse 6 aufgenommen, die Komponente entlang ihrer empfindlichen Achse 7 in eine kraftproportionale Verformung der Doppelbiegebalken 2 mit den Dehnungsmeßstreifen 5 und mittels dor nicht dargestellten Meßschaltung in einen entsprechenden elektrischen Spannungshub umgewandelt. Auf diese Weise ist die Bestimmung der Vortriebskomponente der Dollenkraft in Fahrtrichtung mit hoher Genauigkeit möglich.When using the force measuring device according to the embodiment of a racing rowing boat the sheaves 8 are held on jibs 9 on the boat, between Dolle 8 and boom 9, the force measuring device is arranged. Here, the Dollenachse is designed as a force-absorbing axis 6 of the force measuring device. Each Dolle attacking force is absorbed via this axis 6, the component along its sensitive axis 7 in a force-proportional deformation of the double bending beam 2 with the strain gauges 5 and converted by means not shown measuring circuit in a corresponding electrical voltage swing. In this way, the determination of the propulsion component of the dollar force in the direction of travel with high accuracy is possible.

Die Anwendung der Erfindung ist jedoch nicht auf das Ausführungsbeispiel beschränkt. Vielmehr ist der Einsatz der erfindungsgemäßen Kraftmeßeinrichtung überall dort möglich, wo in ihrer Wirkungsrichtung variabel angreifende Kräfte in einer definierten Richtung zu bestimmen sind.However, the application of the invention is not limited to the embodiment. Rather, the use of the force measuring device according to the invention is everywhere possible where in its direction of action variably attacking forces are to be determined in a defined direction.

Claims

Selective force measuring device for forces whose direction of action is variable and whose component is to be determined in a defined direction, with a measuring element having strain gauges equipped with double bending beam and a measuring circuit for evaluating the resistance of the strain gauges, characterized in that the measuring element (1) consists of two double bending beams (2) which are connected to each other by an axis (6) serving to introduce the force, the axis (6) being in the plane of symmetry of the strain gauges (5) bearing active deformation elements (3) of the double bending beams (2) is located and in the measuring circuit, the sum of the at the of the strain gauges (5) formed Wheatstone resistance bridges resulting electrical voltage swings is detected.

For this

2 pages drawings

Field of application of the invention

The invention relates to a force measuring device for forces whose direction of action is variable and whose component is to be determined in a defined direction. Appropriate application is the Stn'ische and dynamiscne selective force measurement in a plane of rotating forces whose direction of effect is not known. So it is necessary, for example, to determine the propulsive component of the Dollenkraft of racing rowboats.

Characteristic of the known technical solutions

There are known force measuring devices for forces whose direction of action coincide with the sensitive axis of these force measuring devices (Erler, W., Walther, L. Electrical measurement of non-electrical quantities with semiconductor resistors, Verlag Technik Berlin 1971, DE-AS 1 573725). Such force measuring devices have a double bending beam as a deformation body, which is provided with strain gauges whose resistance change is evaluated electrically. The introduction of the force in the double bending beam via a plunger, which lies outside the Symmntrieebono of the double bending beam.

With force measuring devices designed in this way, angular deviations between the direction of action of force and the direction of the sensitive axis are permissible up to 10 ° depending on the desired accuracy, but deviations beyond this lead to large measuring errors due to the increasing transverse force component of the force to be measured. For this reason, such force measuring devices are not suitable to measure variable forces in their direction of action. Furthermore, force measuring devices are known which serve for the separate detection of the components arbitrarily directed forces and / or moments (DE-A 5 2122924). This force measuring device has a linearly elastic cylindrical body on which at least three strain gauges are applied in an arbitrary arrangement. The introduction of the force via a plunger, which acts on the cylindrical body from the outside. The evaluation of the measurement signals obtained from the strain gauges via an elaborate logic circuit, which makes it possible to individually represent the derived via a calibration matrix measurement signals as components of the introduced force. Finally, a measuring device for three-dimensional force measurement by means of strain gauges has become known (DE-OS 3226386). Here, a force-absorbing plate is provided, which is connected to a measuring frame via a plurality of pairs arranged webs. All webs carry strain gauges and serve to detect the force components in the X and Y plane. To initiate the force to be measured on the kroftaufnehmende plate is a bar, which is also provided with four strain gauges for determining the lateral force in the! -Plane in aor Torsionsmessung. The evaluation of the measurement results takes place in a measuring device designed as a bridge circuit, which makes it possible to detect the individual force components.

The effort of the two latter measuring devices is considerable. As a major drawback beyond the insufficient measurement accuracy is to be considered, which is all known measuring devices own. It results from the quark force-dependent feature, i. Their sensitivity to force components perpendicular to their sensitive axis. This disturbing lateral force sensitivity is caused by the eccentric position of the point of force application, se that exerted by the transverse force, a moment on the force measuring, the eirio asymmetric not or only with unreasonably high cost - compensatable deformation of the elastic measuring element, z. B. dos double bending beam and thus causes an undesirable measurement error.

Object of the invention

It is an object of the invention to provide a force measuring device for forces whose direction of action is variable and whose component can be determined in a defined direction with großur measurement accuracy and low technical complexity.