Abstract
(1) The characteristics of indicial and frequency response of the feedback control system with electro-hydraulic servo-mechanism were tested by using the following test signals; step input and sine wave input. And the most suitable operational technique was discussed when employing this system for the automatic position control of cutter bar for tea-plucking machine.
(2) The transfer function of this control system could be approximated as first or second order time-lag element when the transformed output was given as indicial or frequency response.
(3) An increase in the sensitivity of servo-amplifier makes the time response of both indicial and frequency response higher, and the time required for the response to reach the final value is shortened.
(4) As the characteristics of the frequency response, the gain (the ratio of input to output) decreases and the phase-lag increases as the input frequency becomes higher, and the degree of its increase and decrease becomes great in inverse proportion to the sensitivity of servo-amplifier.
(5) When employing this control system for the automatic position control of cutter bar for tea-plucking machine, the desirable characteristics of the frequency response are as follows;
(a) The gain must equal unity or so for the wide frequency range regardless of the sensitivity of servo-amplifier.
(b) The phase-lag must equal the time required for the tea-plucking machine to advance the distance between the sensing plate and the cutter bar. This delayed time was expressed in terms of phase angle as equation (11).
