Abstract
The characteristics of the torque control system were investigated with the method of the spectral analysis to the random inputs having the short period of time.
(1) Tillage torque of the rotary tiller is the random process with the periodical variation components.
(2) It has the peculiar variations according to each arrangement of tines and tillage pitch. As the frequency of the rotary revolution is fo c/s, they are the harmonics of the frequency fo, 2fo, 3fo and 4fo.
(3) The power spectrall density in 4fo is the greatest for the sixteen tines arrangement but in fo greater than in (4) fo for the twelve tines arrangement.
(4) The wave form of the tillage torque was concluded by the theory of the tine arrangement and the driving procedure.
(5) The system may control desirably the tillage depth in accordance with the changes of the tillage pitch.
(6) As the gain to the inputs with the higher frequency is lower, the system is stable enough to do the tillage works.
