Measuring and testing – Inspecting
Reexamination Certificate
2001-08-02
2003-10-28
Noland, Thomas P. (Department: 2856)
Measuring and testing
Inspecting
C073S104000, C033S773000, C033S775000, C033S512000, C600S587000
Reexamination Certificate
active
06637278
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to a measuring system for determining the shape and length of a surface line of a body with a freely movable measuring instrument, which is equipped with a measuring device for measuring the length of a displacement path of the measuring instrument along the surface line and a measuring device for determining angular changes of a measuring axis of the measuring instrument with respect to a predetermined reference axis, with a data transfer device to a computer and a computer which processes the path and angle measurements of the two measuring instruments and generates a representation of the surface line.
Such measuring systems are in particular applied for acquiring and scanning the shape and length of body contours and of ranges of motion in the case of articulated bodies, in particular human bodies. Of particular interest are the acquisition of the shape and length of the course of the vertebral column and measuring for checking its mobility, but also for measuring the course of motions on other joints, such as, for example, hip or knee joints. A measuring system of this type is known, for example, from DE 40 90 228 C1, in which different application feasibilities in the area of measurements on the vertebral column are also described. In this known system, a freely movable measuring instrument is available, which is:connected to a computer for evaluating and representing the data. In the movable measuring instrument a measuring device is available for measuring the length of the displacement path of the measuring instrument, and specifically an electric path-measuring sensing element. This path measuring device includes rollers or cylinders, which, during the displacement of the measuring instrument, track along the surface or line to be measured and means, known per se, for converting this tracking motion into electric signals, for example via an incremental displacement transducer. The measuring instrument further includes also an angle measuring device in the form of a vertical pendulum device. This vertical pendulum device is developed such that it can be applied in two positions pivoted by 90°. This allows in a first measuring process by tracing the surface line with the movable measuring instrument determining curvatures in one direction and by repeating the tracing process and resetting the vertical pendulum device by 90°, curvatures of the surface line in a plane at right angles to [the first plane]. To determine the curvature and shape of the surface line, at specific points, or intervals of the path of this surface line, the corresponding angular deviations via the vertical pendulum and on that basis to determine the curvature of the surface line. The vertical pendulums applied for angle measurements represent relatively sensitive, and also correspondingly expensive, measuring instruments, and, in the commercially available implementations, they also have only a limited angle measuring range. If, in the case of measurements on the human body, for example in patients with back complaints, measurements must be carried out on the standing and also on the lying body, these different measurements require a resetting of the measuring instrument, for example of the vertical pendulum device, for the particular position of the patient. As a consequence, the measuring electronics must also be newly initiated and the originating point of the measurement must be started accordingly. This is time consuming and can also lead to discrepancies of the measuring results and to errors, since movements in the interim by the patient cannot be excluded.
A further measuring system for acquiring the back contour of a human being is known from DE 44 02 562 A1. In this system a vertical pendulum is also applied for angle measurements in the movable measuring instrument. While this vertical pendulum has an increased angle measuring range, it entails, however, additionally the disadvantage that vertical pendulums are sensitive measuring instruments with a complicated interior structure. They are therefore correspondingly expensive and also require careful handling and correct application. During the measurements the vertical pendulum must be oriented as must as feasible in a vertical plane since otherwise the damping could falsify the measurement results. With too great a deviation from the vertical plane, measurements can even become impossible.
In practice difficulties are therefore repeatedly encountered since the measured object on which the shape and length of a surface line is to be acquired, must be moved into a position which corresponds to the permissible measuring range of the measuring system. In particular in the case of measurements on the human body and wherever measurements or sequences of measuring series must be carried out rapidly, this makes the course of measurement difficult. The known measuring systems therefore require corresponding training and practice in the application. Even with correspondingly trained operators the time expenditure for carrying out measurements is, to some extent, still considerable, and, in particular, resetting the angle measuring device and the respective initialization are time-consuming.
SUMMARY OF THE INVENTION
The objective of the present invention is to provide a measuring system or a measuring instrument, with which the acquisition of shape and length of surface lines of a body in a plane over an angular range from 0 to 360° is possible, with changes of position of the measuring instrument or with changing measuring processes no initialization and calibration of the measuring instrument is necessary, the measuring device for determining the angular changes in [three-dimensional] space is structured simple and freely movable, and the course of the surface line in the same measuring process can be determined with respect to two measuring surfaces, oriented at right angles to one another, or as a space vector.
This object is attained through the features defined in the claims to and forming part of this application.
In the measuring system according to the invention the movable measuring instrument is equipped with a measuring device, known per se, for measuring the length of a displacement path along a surface line, as is described in prior art. In combination with this length measuring device, known per se, the measuring device for determining angular changes of a measuring axis of the measuring instrument, is developed with two acceleration sensors. Application of acceleration sensors for determining angular changes of the measuring device yields the advantage that sensors can be employed which have a precisely defined measuring axis and, additionally, no movable parts exist which must be supported such that they are pivotable about an axis or are equipped with damping elements. This significantly simplifies the structure of the measuring device for determining angular changes and the susceptibility to malfunction is considerably reduced. The acceleration sensors proposed for use, are sensors which normally are applied to determine accelerations and decelerations of moving objects in the direction of their measuring axis. But such sensors, known per se, also have the property that even in the stationary state, i.e. without a motion component in the direction of their measuring axis, they output measuring signals with angular changes of the measuring axis. This effect can be traced back to the normal gravitational force, or acceleration due to gravity, which always acts on the sensor. If an acceleration sensor is oriented such that the measuring axis is parallel to the gravitational axis, the full acceleration due to gravity acts on the measuring element of the acceleration sensor. If the measuring axis of the acceleration sensor is precisely at right angles to the gravitational axis, the measuring element of the acceleration sensor is not deflected and no component of the acceleration due to gravity acts in the direction of the measuring axis. Depending on t
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Noland Thomas P.
Notaro & Michalos P.C.
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