Project Description
Brief Introduction
Fruit firmness is an important quantifier for overall fruit quality, and as such, the detection and evaluation of fruit firmness is of great use to those involved with the distribution and processing of fruit. My project was about investigating methods of non destructive fruit firmness testing focusing on non contact ultrasonic methods.
Abstract
Many NDT methods have been applied to determining fruit firmness including Ultrasound, infrared spectrometry, acoustic and the laser-air puff method. The use of any of these methods means that the older, manually applied and often destructive testing methods may be replaced with automatic Non-destructive systems allowing for faster testing for all individual pieces of fruit. The difficulties with most of these methods is that they lack the appropriate levels of accuracy, are too slow and in some cases are simply too awkward to implement in a automatic system such as a large scale fruit sorter.
This thesis investigates the possibility of applying Non-Contact Ultrasound (NCU), and other methods, to this problem based on more conventional contact based experiments. The investigation lead to the design of a NCU capable device made up of Off The Shelf equipment that interfaced with an IBM PC using the PCI interface. Also, simulations of how fruit might respond to ultrasound where made to confirm what was found in the available literature.
Based on the literature and the results of the simulation, it can be inferred that ultrasound is sufficient for estimating the firmness of fruit. Based on timing calculations, the system designed was shown to be fast enough to facilitate real time processing of fruit, although more work is needed on the classification algorithms to confirm that a full system would be also be sufficiently fast.