Adaptive Feed Rate Control of Small Combine Harvester (I)

Digital Sampled Data Adaptive Control System

Abstract

The digital sampled data adaptive control system with the logical operation of the combine was investigated. In this control system 3 inputs of the engine load, the feed rate and its fluctuation were sensed, and the traveling speed of the combine was controlled. The setting value of the feed rate was automatically adjusted to adapt to the change of the grain conditions.
The feed rate was detected as the straw layer thickness on the lower conveyor of the combine by a differential transformer. The engine load was detected by a tachometer generator as the threshing cylinder rotating speed. Sampling and holding was done by RST flip-flop after transforning two input signals into on-off signals.
The fluctuation of the feed rate was detected by comparing the present feed rate with that of 4.5 seconds before (the time required for the crop detected by the differential transformer to reach the threshing chamber).
The increase of the traveling speed of the combine was done in case that the load in the threshing chamber was expected to decrease orr the engine output had surplus. Decreasing of it was done in reverse condition.
The setting value of the feed rate was lowered by giving lower speed than R2 judging from the logic that the setting value was too high, if both signals of the feed rate were lower than its lower limit (LL) though the engine was overloaded (in FIG. 1), It was in reverse if both signals of the feed rate were higher than its upper limit (LH) even though the engine speed was over upper limit (RH),
With Boolean algebra these logics were calculated and simplified to construct electronic circuit.
The field experiment of this adaptive control system using g P. S. small combine with hydrostatic drive showed better results than the conventional control system.