Performance Testing of Thermal Cutting Systems for Sweet Pepper Harvesting Robot in Greenhouse Horticulture

Abstract

This paper proposes design of end-effector and prototype of thermal cutting system for harvesting sweet peppers. The design consists of two parallel gripper bars mounted on a frame connected by specially designed notch plate and operated by servo motor. Based on voltage and current, two different types of thermal cutting system prototypes; electric arc and temperature arc respectively were developed and tested for performance. In electric arc, a special electric device was developed to obtain high voltage to perform cutting operation. At higher voltage, electrodes generate thermal arc which helps to cut stem of sweet pepper. In temperature arc, nichrome wire was mounted between two electrodes and current was provided directly to electrodes which results in generation of high temperature arc between two electrodes that help to perform cutting operation. In both prototypes, diameters of basic elements were varied and the effect of this variation on cutting operation was investigated. The temperature arc thermal system was found significantly suitable for cutting operation than electric arc thermal system. In temperature arc thermal cutting system, 0.5 mm nichrome wire shows significant results by accomplishing harvesting operation in 1.5 seconds. Also, thermal cutting system found suitable to increase shelf life of fruits by avoiding virus and fungal transformation during cutting process and sealing the fruit stem. The harvested sweet peppers by thermal cutting system can be preserved at normal room temperature for more than 15 days without any contamination.