Abstract:
An electrostatic force generator is disclosed. The electrostatic force generator includes an RF AC voltage source, a capacitive module, a resonant capacitive-inductive bridge (CIB) module, a lock-in amplifier module, and a proportional-integral-derivative (PID) controller. The resonant capacitive-inductive bridge module converts the differential capacitance to a differential signal. The differential signal from the resonant capacitive-inductive bridge module is demodulated at the RF excitation frequency by the lock-in amplifier module. The PID controller receives the output signal from the lock-in amplifier module and generates two audio frequency AC signals to generate a compensation electrostatic force and maintain the capacitance balance inside the capacitive module.
Abstract:
For the automatic weighing of a beam balance with electromagnetic force compensation, substitution control weights and digital recording are used. An indicator signals the position of balance beam to a microcomputer. The load compensation is carried out with a limited number of variable electromagnetic compensation forces of constant amplitude, which are produced by means of a corresponding number of discrete constant currents. The currents are graded according to decreasing powers of a numerical system of a suitable basis; as a rule, just like decimally organized figures according to units and powers of ten of these units. Starting out from upper to lower decades, a count is made in each decade as to how many compensation units are needed in order to overcompensate the load. For this purpose, a decision is made merely in the case of every compensation step--without determining precisely the rest position of the balance beam--as to whether the load applied is larger or smaller than the compensation force. Whenever the indicator signals an overcompensation, then the preceding counting step is regarded as the weighing result of this decade. Numerical correction values are assigned to each compensation step of each decade. The weighing results develops from the sum of the weighing results of all decades and the sum of correction values which had been assigned to the evaluated compensation steps of each decade.
Abstract:
The invention relates to a fiber optical device for measuring physical magnitudes such as force, elongation, pressure, acceleration, temperature, etc., comprising a transducer unit and an electronic unit, in which the quantity to be measured is supplied to the transducer unit to affect the resonance frequency of an oscillating body included in the tansducer unit by changing the dimensions, mass, density, modulus of elasticity and/or mechanical stress of the body. A property of the body oscillation, such as frequency, phase position and/or amplitude, is used as a value of the quantity to be measured. The oscillations of the body are detected optically by means of a fiber optical position/movement detector.
Abstract:
A closed loop control system for maintaining a force transducer assembly in a balanced position is disclosed. The control system has a feedback loop control circuit for providing a force rebalance signal at one of a plurality of predetermined discrete amplitude values during each of a plurality of successive equal duration time intervals. The signal has a constant amplitude during each interval. The control circuit further provides a respective digital representation for each amplitude value of the rebalance signal for each of the successive time intervals. Thereby, a precise determination of the value of the time-force product can be generated with the concomitant determination of the forces acting upon the force responsive transducer. The control system is particularly useful for non-linear transducers, such as square law devices where the time-force product is difficult to determine with continuously variable amplitude values.
Abstract:
Es wird ein Bewegungs- und Kraftsensor angegeben, der eine Fassung zur Aufnahme einer Kugel oder Walze sowie eine in der Fassung aufgehängte Kugel oder Walze mit ferromagnetischem Material umfasst, wobei die Kugel oder Walze drehbar aufgehängt ist, der weiterhin wenigstens einen magnetoelastischen Sensorkopf zur Aufnahme der magnetischen Permeabilität der Oberfläche der Kugel oder Walze und eine Auswerteeinrichtung aufweist, ausgestaltet zur Ermittlung einer Drehbewegung der Kugel oder Walze anhand eines Vergleichs der vom Sensorkopf gemessenen Permeabilität mit in der Auswerteeinrichtung gespeicherten Daten zur Permeabilität der Oberfläche der Kugel oder Walze.
Abstract:
Embodiments of the invention relate to a thrust stand and a method of measuring thrust. Embodiments of the invention pertain to a method of calibrating a thrust stand. Embodiments of the subject thrust stand can incorporate a passive eddy current based damper. Specific embodiments of the passive eddy current based damper can function without contact with the balance arm. Further specific embodiments of the passive eddy current based damper can be used in a vacuum. Embodiments can utilize signal analysis techniques to identify and reduce noise. A logarithmic decrement method can be used to calibrate the thrust stand. Force measurements can be made with embodiments of the subject thrust stand for a standard macroscale dielectric barrier discharge (DBD) plasma actuator and/or other thrust producing devices.
Abstract:
Die Erfindung bezieht sich auf eine Kraftmessvorrichtung, umfassend - einen an einer Basis abgestützten Verformungskörper (10), welcher sich ohne äußere Krafteinwirkung (13) in einer Nulllage (12) befindet und welcher durch eine äußere Krafteinwirkung (13) auslenkbar ist, und - einen Sensor (30), welcher ein Piezoelement umfasst und mittels dessen ein von der Verformung des Verformungskörper (10) abhängiges Signal erzeugbar und an eine Steuereinrichtung übermittelbar ist, wobei eine für die äußere Krafteinwirkung (13) repräsentative Messgröße mittels der Steuereinrichtung ermittelbar ist. Die Erfindung zeichnet sich dadurch aus, dass ein Aktor (31), welcher ein Piezoelement umfasst, in Abhängigkeit von dem Sensorsignal durch die Steuereinrichtung so ansteuerbar ist, dass dadurch eine Rückstellkraft entgegen der äußeren Krafteinwirkung (13) auf den Verformungskörper (10), welcher dadurch in seine Nulllage (12) zurücküberführbar ist, ausübbar ist.
Abstract:
La présente invention concerne un dispositif (101, 102, 103, 104) de mesure de force, comprenant: un organe mobile (1); des moyens de guidage (2) de l'organe mobile selon au moins un degré de liberté; des moyens (3) de mesure de position de l'organe mobile; au moins un actionneur (4) pour soumettre une force d'actionneur (7) sur l'organe mobile; un système de commande (5), agencé pour envoyer un signal de commande à l'au moins un actionneur, la force d'actionneur dépendant du signal de commande, le système de commande étant agencé pour modifier le signal de commande en fonction d'une mesure de position de l'organe mobile par les moyens de mesure de position; des moyens de mesure de force (6) agencés pour, à partir du signal de commande envoyé par le système de commande à l'au moins un actionneur, fournir une valeur d'une force à mesurer (8) s'exerçant sur l'organe mobile et distincte de la force d'actionneur. Les moyens de guidage de l'organe mobile sont dénués de force de rappel sur l'organe mobile selon l'au moins un degré de liberté.