Abstract :
This paper gives a brief account of a series of measurements of the movement of the controller handle and of the error of aim under conditions simulating the laying of a gun on a moving target by manually-controlled power operation. The results are analysed with the object of obtaining the ¿ operator´s response, ¿ i.e. the relationship between the movement made by the operator´s hand and the error and its variations as seen by the eye. It is found that the response relationship is non-linear, but the relationship may to a useful extent be approximated by a ¿ nearest linear law, ¿ namely that the speed of handle movement is dependent upon both the error and the rate of change of error, subject to a time delay which corresponds to that known to be involved in nerve transmission. The actual movement is found to differ from this relationship, both in being intermittent or jerky and also in being subject to apparently haphazard variations. A project for further investigation is outlined by which the difficulties in more detailed analysis may be overcome. On the basis of the results so far obtained it is shown that an explanation is provided for some of the outstanding phenomena observed in the laying of guns and in other cases of manual control of power-driven apparatus, and it is shown that there is an upper limit to the accuracy of control obtainable. Finally, the paper shows how the error incurred in tracking a target is fundamentally related to and depends upon the time delay which occurs between the stimulus received by the eye and the resulting muscular response, and gives comparative values for the theoretical limit of accuracy obtainable with controllers having various types of response characteristics, as a function of this delay time, for an otherwise ideal operation. The lines along which an improvement of performance may be sought are discussed in the light of these limits and the other phenomena observed.
