Investigating the Use of Low-cost and Low-power Millimeter Wave RADAR to Improve Quality of Tomato Harvesting

Low-cost and low-power millimeter wave RADAR is a novel and promising method that is emerging in the field of sugar content analysis. As fruit ripens, its sugar content increases while starch content reduces, this in turn lowers the relative permittivity. Thus the ability to measure sugar content in a whole fruit will enable better harvest quality. RADAR provides a fast, non-destructive method that could be used to measure properties of fruit which is considered ideal compared to traditional methods of measurement involving direct contact. In this study, the measurement setup of Acconeer A1 pulsed coherent RADAR sensor was investigated and proposed. Measurements were taken to correlate the RADAR reflectance readings with the analysed soluble sugar content (SSC) from High Performance Liquid Chromatography (HPLC), a well-established destructive chemical analytical method. Linear regression was used to statistically analyse the RADAR against fructose and glucose. Out of these two SSC, fructose content proved to have a stronger correlation with RADAR measurements and should be explored for future work. Additional future work to reduce measurement variability is to utilise a different RADAR setup whereby the transmitter and receiver angles can be varied to study the effect of the energy dispersion.