Desenvolvimento de um sensor capacitivo de medição da massa específica de sementes para automação da mesa de gravidade

Abstract

The automation of unit operations for seed processing is a real necessity to improve the operation, operation and adjustment of the machines. The specific gravity of the seeds may be associated with vigor, because seeds with problems of filling, attacked by insects or even broken, suffer a reduction of the specific gravity, consequently a decrease in the physiological quality of the seed lot. The objective of this work was to develop a capacitive sensor to measure the specific gravity of seeds and analyze the association between the relative dielectric permittivity and the physiological quality of seeds benefited in a gravity table. In the experiment soybean and coriander seeds were used. Pearson correlation was used to analyze the variables of specific gravity (ρ), water content (𝑈) and temperature (𝑇) with the total relative (𝜀), real (𝜀′) and imaginary (ε'') In the frequencies of 1 kHz, 10 kHz and 100 kHz. Pearson correlation was used to analyze the association between relative permittivity and the physiological and physical attributes of the seeds. Relative dielectric permissiveness, physiological and physical attributes were submitted to analysis of variance and, if significant, the variables were compared by the Tukey test at 5% probability. There was a high correlation between the variables with the relative permissivity analyzed at almost all frequencies, however, there is an improvement in the stability of the data with increasing frequency. The sensor was efficient for the determination of the specific gravity of the seeds, previously knowing the water content and the temperature of the seeds. By the Tukey's test the relative permissiveness allowed the rank of discharge nozzles, similar to the physiological and physical attributes except emergency. The linear regression indicated that with increasing frequency, the compliance of permissiveness values improved. The sensor was relatively efficient for determining the specific gravity.