Design of On-line Detection System for Apple Early Bruise Based on Thermal Properties Analysis

How to distinguish the early mechanical bruise is a persistent problem in fruit defects sorting system. Due to the sensitivity of infrared camera to object surface temperature changes during thermal excitation, an on-line active thermal imaging system for apple early bruise detection was designed, which consist of transport and heating unit, apple orientation and rotation unit, bruise detection and control unit. With the analysis of fruit surface thermal properties on-line in computer, the bruise defect can be recognized effectively in experiment. This online test results show that a 90% recognition rate for defective apple and a 83.3% recognition rate for sound apple, while the good apple with calyx can be completely distinguished.