CA2082345A1

CA2082345A1 - Computer hinge caliper

Info

Publication number: CA2082345A1
Application number: CA 2082345
Authority: CA
Inventors: Kenneth George Wiebe
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-11-06
Filing date: 1992-11-06
Publication date: 1994-05-07

Abstract

Abstract A computerized hinge caliper for measuring tree growth ring radial increments, seashell yearly growth accretions, or other objects. The computerized hinge caliper includes two legs, hinged at one end with terminal points on the opposite ends, a variable electronic transducer and an electrical switch. The transducer and switch are electrically connected to electronic circuitry and a computer.

Description

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Spe~ification The present invention relates to hinge calipers cc)mprising two legs joined at one end by a hinge, and terminated with points on the opposite ends. In this embodiment, a variable electronic transducer interacts with the legs such that as the angle between the legs changes, a corresponding change occurs in the transducer. This change is intended to be interpreted by circuitry and software in an electrically attached computer. An electrical push button switch is mounted on one leg of the caliper, and depression of this switch can also be interpreted by circuitry and software in an electrically attached computer.
When foresters make determinations about a particular stand of trees, they often perform a series of analytical measurements on a selected sample of trees within that stand. This is known as 'stem analysis'. One particular set of measurements involves sectioning the tree stems into what are known as 'cookies' due to the similarity of shape of the tree stem sections and cookies.
These 'cookies' are subjected to rigorous measurements~ one of which is a series of stem radial increment measurements. In essence, each cookie has each growth ring radius measured several times and each measurement recorded. These measurements are taken along several different rays on each cookie. The rays are hand drawn on each cookie and emanate from the centre to the outside ring. This is done in order to accurately gauge the volume of wood in a non-syrnmetrical tree stem. In any given stem analysis project there may be hundreds or even thousands of 'cookies', each one of which may have hundreds of growth rings, and each growth ring may have its radius measured along three or four rays.
The measurements are recorded on paper and then entered into a computer far filrther calculations and analysis. This is a time consuming and error-prone process.
This process is unsatisfactory because of the substantial time and operator skill required to measure, gauge, record, and transcribe hundreds or even thousands of measured values into a computer. It is also unsatisfactory because operator fatigue or inattention results in incorrect and inaccurate measurement data being recorded. The time and expense involved in this analysis means that it is often not performed to the extent it should be, which can result in unnecessary implementation of costly forest treatment regimes or environmentally unsound logging activities. Mechanisms for automating the measurement process are available which work on entirely different principles, and are composed of large, fixed location, precision machinery which is operated by highly skilled people.
I have found that these disadvantages may be overcome by providing a computerized hinge caliper which contains a variable electronic transducer and an electronic switch connected to a computer. Coupled with appropriate software, this type of caliper enables a relatively unsophisticated operator to make many accurate distance measurements in a short period of time, and automatically have those measurements recorded in a computer sy.stem. This reduces the time and expense of such analysis by at least an order of magnitude.

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In drawings which illustrate this embodiment of the invention, Figure 1 is a front view, Figure 2 is a rear view, Figure 3 is a side view, and Figure 4 is an electrical schematic.
The front leg I has a bushing and set screw 5 fastened to the transducer 4 shaft. The transducer 4 body is fixed to the rear caliper leg 2. The electrical switch 3 is fixed to the rear caliper leg.

In use, the operator runs the computer program which recognizes the calipers. Certain initial descriptive information may be entered into the computer at this time. Optionally, the software may be instructed to calibrate the calipers from time to time as necessary.
When calibrating, a rule is used and the caliper is opened to preset distances along the rule, and the switch is depressed. The software will build a table of standard values for each measurement which it will then use in the future for distance determination. From time to time, this calibration table should be updated to account for wear in the mechanism.
In operation, the operator places the terminal point of the front caliper arm t at the initial measurement point of the object to be measured. The terminal point of the rear caliper arm 2 is placed at any point diametrically opposite the ray being measured. Then the switch 3 is depressed to set the 0 measurement. Thereafter, the terminal point of the front caliper arm I is placed on each successive point to be measured and the switch 3 is depressed.
The computer software will indicate a valid measuremer~t has been recorded by issuing a short tone. The operator will continue on to the next measurement point and repeat this process for each desired measurement on the object being measured. Through this method, the operator need not remove his attention from the object being measured until all measurements have been made. Each measurement takes less that one-half second to measure and record on an industry standard personal computer.
Though this invention has been designed primarily ~vith forestry applications in mind, it is readily applicable to many other disciplines. In its current form this invention uses a resistive transducer but a variable capacitor, variable inductor or optical transducer may be readily substituted for equal or better accuracy, should an application require it. The variable resistor transducer has been employed initially7 due to the ease of acquiring standard computer interface circuitry and minimal electronic circuit complexity.

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Claims

1. A computerized hinge caliper for measuring distance, said caliper comprising: two hinged legs;
a transducer attached to the two legs such that the relative angle between the legs is sensed by the transducer and translates said angle into an electrical change in the transducer;
an electrical switch such that said switch may be sensed by attached electronic circuitry and/or computer software.

2. The computerized hinge caliper of claim 1, wherein the transducer component comprises the mechanical elements of the hinge mechanism.

3. The computerized hinge caliper of claim 1, wherein the electrical switch is not mounted on the caliper leg, but is operated remotely by means of a foot switch or other external event.