1980 Volume 42 Issue 1 Pages 85-89
(1) For the use of automatic position control of cutter bar for tea-plucking machine, two control systems, the on-off control system with limit switch and solenoid valve and the feedback control system with electro-hydraulic servo-mechanism, were constructed and the performance of these two control systems was examined respectively by practicing the plucking test using the machine equipped with the control system in the tea garden.
(2) With the on-off control system, the accuracy of plucking depends greatly on the operation interval of limit switch, and good results were obtained without vibration when the operation interval of limit switch was 5mm or so and the vertical movement velocity of the cutter bar was about 0.03m/s. This control system was considered to be the most satisfactory system in view of its functional properties, manner of treatment and low cost.
(3) It was proved that the feedback control system with electro-hydraulic servo-mechanism was functionally for superior than the on-off control system. However, there may exist problems of treatment and cost on the use of the feedback control system, and this system cannot be offered to employ for the present.
(4) With both two types of the automatic position control systems for the cutter bar mentioned above, desirable position control of cutter bar should be done through the following procedure;
(a) Putting load of about 1g/cm2 on the sensing plate according to the tea shoot condition, and the cutter bar was setted at the same level surface as the sensing plate for a while.
(b) In the beginning, test plucking was practiced and according to its results, the relative position of the sensing plate and cutter bar should be corrected in this way; the sensing plate was brought down for deep skiffing and raised up for light skiffing.
The following would be pointed out; what tea plants are controlled to grow uniformly was very important for plucking tea leaves equally at the optimum plucking surface all over the tea garden.
