Design and Experiments of Coaxial Contra-Rotating Sugarcane Base Cutter with Time-Frequency Control

Abstract

Abstract. A laboratory-based cutting platform with speed control was developed to investigate the cutting mechanism for the support-cutting of sugarcane. A coaxial contra-rotating base cutter was designed to facilitate sugarcane support-cutting in a laboratory setting. The cutting platform, which consists of two discs with cutting blades, was driven by two variable-frequency electric motors. To manipulate the speed of each motor independently, a time-frequency controller was designed to handle system nonlinearity and to maintain system stability subject to speed variation. To validate the cutter design, a series of idle running tests and cane-cutting tests were implemented using the laboratory-based cutting platform. The results indicated that the rotating speed of the two cutting discs could be adjusted smoothly. The controller capped the overshoot under 1% in the speed step response and kept the fluctuation of the speed difference of the two cutting discs at less than 2.5 rpm. Evaluating the cane quality of support-cutting against free-cutting showed that support-cutting decreased the stubble damage rate from 22.67% to as little as 6.67%. The results also suggested that the time-frequency-controlled cutting platform was feasible for subsequent investigation for a better understanding of sugarcane support-cutting, such as the variation of energy consumption or stubble damage rate with different rotating speed or different blade shape, which will provide constructive suggestions for the future base cutter design. Keywords: Base cutter, Support-cutting, Cutting platform, Time-frequency control.