Yoshikazu Sawaragi

On the Cycling of a Real Control System Caused by a Backlash in the Pneumatic Controller

In this paper, the authors analysed a cycling phenomenon of a real control system. As the results, after some experiments we came to the conclusion that this phenomenon was caused by a backlash in the pneumatic controller. Carrying out the analysis of the control system including this non-linear characteristic by means of the gain-phase plane, it was found that the cycling frequency and amplitude were nearly in agreement with the experimental results. By the gain-phase plane the cycling should occur when the proportional sensitivity of a Paction controller is 19.0 db, but by our experiments it occurred when the proportional sensitivity is 18.5 db. The larger the sensitivity is, the larger the frequency and amplitude of cycling.

On the Creep of Rubber Vibration Absorber of Tread Type

In the creep of rubber vibration absorber of Tread type, we recognized experimentally the existence of virgin curve and found the creep strain was not proportional to the stress at a certain time after loading. These phenomena are explained reasonably by the dynamical model proposed by Sawaragi and Tokumaru for nonlinear viscoelastic bodies. In practice, it is not desirable to use these materials in the state in which virgin curve will be obtained, for then the permanent set from internal solid friction results. In order to make these materials useful in practice, we must get them to creep to a certain degree and to recover enough. Then we can get the stable state of these materials. In this report a suitable load and the duration time of load to give such a stable state are estimated.

On the Stationary Oscillation Induced in the Control Circuit by the Non-linear Characteristics in the Relay

In case the non-linearities are kept containing in the control circuit elements, the stationary oscillation which has the circular frequency and the amplitude determined by the nonlinear characteristics and the chasacteristic value of the circuit occurs. We hereby consideded the dead zone and saturating characteristics in the relay of pilot valve type, and found, by means of analysis and experiment, the stationary oscillation induced in the control circuit by the above characteristics in the circuit having the controller of the three types ; that is, integral, proportional and proportionl integral action. Thus it will be possible to observed the effect of the non-linear characteritics on the stability of the automatic control circuit.

The Effect of Friction in the Automatic Control System on Controlling Action

In the case where the effect of solid friction and inertia is studied at the same time, it is very difficult to solve the problem by the analytical method using differential equations. In such a case, it is effective to apply the vector locus which is obtained by means of approximate linearization of the non-linear element with solid friction. But the method of linearizing used hitherto does not bring exact results. It is especially so in the case of stop motion. Therefore, authors drew the vector locus utilizing Hartogs exact solution, and could obtain excellent results. In this paper, their method is explsined and the effect of solid friction on the stability of control system is considered.

On the Preventive Method against Hunting Utilizing Non-linear Characteristic of Pilot Valve

In the automatic controller with hydraulic servomotor, the pressure 1iquid to pilot valve is throttled frequently in order to prevent the hunting. Authers carried out experiments and analysis to give a theoretical basis to this preventive method. And the following were concluded : As to the steady oscillation due to the saturating characteristic of pilot valve, its frequency is equal to the frequency of linear control system at critical stable state, and its amplitude is proportional to the ordinate of intersecting point of saturating characteristic curve and critical stability line of linear control system. Therefore, inversely utilizing above conclusion we can practise this preventive method against hunting rationally.

On the Dynamical Characteristics of Rubber Vibration Absorbers for Automobile Engine Mounts (In Compression)

最近自動車ならびに他の車両においていわゆる防振ゴムを使用することが多くなった, しかして防振ゴムの動的な特性が明らかでないためその設計に当り適当な基準となるべき計算式が確立されていないように考えられる.ここにおいて筆者等は自動車発動機架に使用されるある種の防振ゴムについて動的な実験を行いその性質を調べた.この際ゴムの非線型性と履歴曲線をえがくことを念頭において動的な特性を静的特性より適当な計算式によって求めることが一つの実験的な係数の導入により容易に行えることを提唱したものである.

On the 1/3 Sub-Harmonic Resonance of the System with Non-Linear Restoring Force

In this report the sub-harmonic resonance of the dissipative system with the restoring force represented by a cubic curve is treated. The authors tried to solve this problems by Fourier series and investigate the stability of the solutions, and then acquired the graphical solution which is useful for actual practice We made an experiment to see the validity of the calculation, that is, we could find how the magnitudes of damping force and external force affect occurrence of sub-harmonic resonance in the non-linear system.

On the Vibration of a System with Variable and Non-linear Restoring Forces

In this paper, we investigate the character of the free vibration of a system whose equation of motion is given by the formula : [numerical formula], and compare the results of the calculations with those of the experiments. In our calculations, we assume a sinusoidal solution with half frequency of variable as a periodic one. Adopting the new method of successive approximation, we obtain theoretical expressions for this problem with sufficient accuracy. This enables us to examine the stability of vibration. It is shown that coincidence between our calculations and experiments very satisfactory.