Torque Control of Rotary Tiller (II)

The Response Characteristics to the Long Periodical Variation

Abstract

The torque control system which controls the resistant torque of the rotary tiller consists with the gear type torque detector, the control valve and the power cylinder. To find the control system responses to the periodical variation with a long period of time such as the change of the tillage depth by the tractor pitching, we made a ridge and a ditch on the field and then field experiments were done crossing them.
(1) Eliminating the components of short periodical variation such as each tine impact, the responses to the tractor pitching at the ridge and the ditch were good.
(2) As the tractor is running on the flat field after passing over the ridge, the response of the system is affected by the pitching on it and has the damping oscillation curve with over shoot
(3) The response of the system of which the spring constant k₁ is larger and the tillage pitch is smaller, is more stable and its torque variance is smaller. By the experiments it is obvious that the stability is higher but the sensibility is lower as the gain constant K of the system is smaller.
(4) Analyzing the damping oscillation curve of the rotary displacement on the flat part of the field, we obtained the transfer function of the system with smoothing inputs. This transfer function is the same type as the theoretical transfer function but has smaller gain constant and larger time constant.