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A mechanical binary logic function generator might be defined as a mechanical device which can generate a specific logic function from two or more binary inputs. The output may also be binary. Little formal investigation has been done in this field prior to this study although the inherent reliability advantages of these mechanisms make them a potential useful device in many fields.
The purpose of this study has been threefold, (1) to derive a technique by use of which a mechanical binary logic function generator may be derived, (2) to determine methods by use of which the expected accuracy of a given function generator may be evaluated, and (3) to numerically evaluate the accuracy of a particular logic function generator, thereby giving an approximate idea of the accuracy to be expected from typical logic function generatorв.
The design technique which is derived consists of three steps:
(1) The desired logic function is defined and referred
to as the output of the mechanism. Since there are two binary inputs to the linkage, each point on the mechaniam will have four possible positions. The four positions of one particular point, A on the coupler link are known as "A points" and form the "delta pattern". These points have particular importance in the overall design. The determination of delta patterns which yield the de-sired output constitutes the primary procedure step.
(4) Having selected a delta pattern, the designer then is able to design the input links by use of a delta pat-tern atlas, similar to the atlas which is included in the appendix of this writing
(3) Optimisation techniques are next applied in order to improve the output accuracy of the mechaniem. A graphical, an analytical and an electronic computer technique are possible optimizing methods.
The degree of precision of the mechaniam is important not only because it determines the quality of the mechaniam but also because the degree of accuracy dictates whether miniaturization of the particular linkage is feasible. In order to evaluate the accuracy and the feasibility of miniaturization of these linkages, either an analytical technique or an electronic computer programming method may be used.
The results of an accuracy analysis on one particular mechanical logic function generator showed that a deviation of 0.005 inches in the length of any of the 15 linear parameters would never cause the out-put to deviate more than two degrees and generally no more than 0.5 degrees. This fact was based upon average link lengths of one inch. As the links are made longer or the tolerance is held tighter, the deviation becomes proportionately less. Similarily, as the links are designed shorter or the tolerance is increased, a greater deviation of the output angle results. The result in this particular case may be expected to be fairly typical of other logic function generators. However, each individual mechanism may yield accuracy results considerably different.
Methods of improving accuracy in a given generator by redesign of only a portion of it are readily applicable. Therefore, it is felt that the numerical results stated above are very conservative as compared to other logic function generator designs.
In conclusion, it is felt that these mechanisms have a definite potential use in engineering. The use of mechanical devices such as these has certain inherent reliability features that its counter-parts do not. The conservative accuracy figures stated above indicate that miniaturization of these linkages is indeed feasible.