This paper describes the results of two-axis manual tracking control systems which are compounded with two single-axis systems, by using a complex display and operation.
Each of the reference values is independent Gaussian noise angular frequency of break point is 0.5-6.0rad/sec. The display is a two-channel synchroscope. The controller is a two-axis stick manufactured by authors and also additionally knobs, and its values operated are transfered to D.C. voltage by potentiometers. And each of the controlled systems is propotional dynamics without cross coupling.
The results are shown as follows. 1) Horizontal and vertical manual tracking control well agreed with each other. 2) Pursuit and compensatory manual tracking task well agreed with each other. 3) Each of control performances is approximated by A× (the angular frequency of break point of reference value) B, where A=0.207-0.218, B=0.843-0.866, and correlation coefficients are 0.995-0.998. 4) Cross coupling in the human information processing system from eyes to arm is little. 5) Two-axis stick is superior in the case of two-axis manual tracking control and also knob in the case of single-axis.
Furtter investigations which is examining the influence of cross coupling between horizontal and vertical controlled systems and its dynamics, are carring out.

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Two mechanisms of vergence eye-movement and accommodation in human eyes are connected to each other constructing a control system which is called the accommodation-vergence eye-movement control system. The response of this controll system was measured when a subject watched a moving target displayed on a stereoscope. The relation between vergence and accommodation in this case is different from that measured when a subject watches a real three-dimensional object. However it is infered that there exists substantially no difference between the characteristics of the control system in these two cases.
Then we concluded that the characteristics of the connecting mechanism between vergence and accommodation did not change according to the characteristics of inputs. And we proposed a fundamental linear model of the accommodation-vergence eye-movement control system.
Changes of the characteristics of the control system with time in stereoscopic vision were measured, and their relation to asthenopia was discussed.

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The vibration of the vibrating tools such as chain saw, pneumatic hammer, rock drill, etc. often causes damage to worker's nerve, muscles, joint of elbow, hands (as the Raynaud's phenomenon) and shoulders.
When we design the tools and estimate the vibration greatness of them, the dynamic characteristics of human body is very important but it is not well understood today.
The author investigates the vibration of the vibrating tools and the dynamic characteristics of human body exposed to vibration which is similar to that of the vibrating tools. The investigation has been done for the typical posture of the worker using vibrating tools by both hands. Coil springs are used in the experiments. As far as practical use is concerned, a dynamic model of human body and the effect of coil springs are presented.
The author also investigates the finger tips transmissibility of vibrations from hand to finger tips.
These result will be useful as the basic data for designing the vibrating tools.

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Past works concerning the human operator dynamics are replete with the single-loop characteristics. Multi-loop control characteristics of the human operator have been unable to be evaluated from the single-loop data due to a number factors that are unique to multi-loop systems. One of the important factors in the multi-loop control system is the scanning characteristics exhibited by the human operator.
An experiment has been made to investigate the scanning rule of the human operator controlling a multi-loop system with separated displays. It has been found out that the human operator sets his permissible error region in each display and controls the system referring to the permissible error region. As a result of this experiment, a scanning model is proposed and the distribution functions of fixation time and sampling time are studied theoretically.

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