A device for acceleration measurements and, in particular, for gravitational field measurements in, for example, earth orbits, which has a body arranged movably in a force field, the position of which can be detected by a position location device. The force acting upon the body is anisotropic and, at least in the direction of the acceleration to be determined, is not a linear function of the deflection of the body from its resting position. In a preferred further development the body is suspended by four tension springs, which in the resting position of the body are arranged in a plane perpendicular to the direction of the acceleration to be determined, and which each form right angles with the adjacent spring. With 3 separate optoelectronic position detector receivers plus corresponding illuminators which provides some measurement redundancy, all acceleration planes can be measured with a great dynamic range. In the main direction, forces as small as 10.sup.-12 g will be measurable. With the position detectors, the device is much simpler and more compact than interferometric devices at equal precision. Other embodiments are described.
A field-based movement sensor adapted for measuring strain along a certain axis in an object on which the sensor is attached. The sensor includes a substrate having a working surface and formed with a pair of fingers projecting from a first direction, and a third finger projecting from a direction opposite the first direction, to a position between the pair of fingers. The pair of fingers and third finger extend generally perpendicular to the axis along which strain is to be measured, with the pair of fingers being moveable with respect to the third finger along the axis when the strain occurs. An electrically charged element for producing an electric field is disposed on the working surface of the third finger, and a pair of field-effect transistors (FETS) are each disposed on a working surface of a different one of the pair of fingers. As the object is subjected to strain causing the pair of fingers to move relative to the third finger, the variation in the strength of the electric field from the charged elements to the FETS is determined and this provides a measure of the variation in distance between the third finger and the pair of fingers and this, in turn, provides a measure of the strain in the object to which the substrate is attached.
A floating mass accelerometer having at least one elastic member contacting a mass that is supported by a low friction surface is disclosed. At least one proximity sensor is located adjacent the mass and provide an output based upon the distance between the sensor and the mass as regulated by the degree of elastic member flexion. Acceleration forces acting upon the mass cause the mass to move in response thereto, thereby causing deflection of the at least one elastic member. The change in distance between the mass and the at least one proximity sensor is relayed to a digital signal processor which processes the acceleration information and sends this information to a display and/or memory unit. In a preferred embodiment, a two axis accelerometer is disclosed wherein acceleration values greater than a predetermined level are stored in memory and may be recalled later to provide an indication as to acceleration forces encountered by the device. Alternative embodiments provide for an pre-impact monitor wherein a buffer holds acceleration information for the last time period; a shipping monitor wherein acceleration forces are time-tagged for later retrieval; a seismic monitor with an optional output relay capable of remote operations.
The present invention relates to a two dimensional stress relaxation testing device in which a plus shaped sample is stretched in mutually perpendicular directions simultaneously to monitor the stress and also the relaxation process of any sheet material in both axes. In view of this advantage, the present device provides the closest approximation to the in situ failure of the material.
A closed loop sensor that utilizes a piezoelectric structure. In one embodiment, driven/non-control electrodes apply drive voltages to the piezoelectric structure and drive/control electrodes apply drive/control voltages to the piezoelectric structure to cause drive mode displacement of the piezoelectric structure and cancel motion induced pickup mode and quadrature displacements of the piezoelectric structure. In another embodiment, pickup/control electrodes detect a pickup signal from the piezoelectric structure corresponding to the motion induced pickup mode and quadrature displacements and apply a control signal to the piezoelectric structure so as to cancel these displacements. In still another embodiment of the invention, an optical sensing device optically senses the motion induced pickup mode and quadrature displacements and control electrodes apply a control signal to the piezoelectric structure so as to cancel them.
In order to improve a sensor comprising an emitting element emitting a bundle of light rays in a direction of propagation, a receiving element receiving the bundle of light rays and having at least one receiving surface for the bundle of light rays, and an evaluating device generating an output signal of the sensor, such that exact determination of the deflection and the direction of deflection is possible, it is proposed that in each deflection position, a receiving surface be illuminated by only a partial bundle of rays of the bundle of light rays in the direction of deflection, that the receiving element generate for the receiving surface an integral intensity signal corresponding to the total intensity impinging upon this receiving surface and that the evaluating device detect the intensity signal and determine the deflection with a processor.
