This study deals with the development of a nondestructive impedance spectroscopic technique that may assess the conditions of the fruits to pluck them with the help of robotic arms. Preliminary investigations are made with the help of two-terminal probe and an accurate LCR meter. The bulk impedance of mango has been measured to characterise raw and ripe fruits. Effective resistance and effective capacitance vs. frequency characteristics have been determined. The bulk effective resistances, of the ripe fruits, are found to be more than those of the raw fruits, in the frequency range of 1-6 kHz. In the same frequency range, effective capacitances of the raw fruits are found more than those of the ripe fruits. In the light of the data obtained, it can be said that the effective resistance may be used to differentiate between raw and ripe fruits in the frequency range of 1-6 kHz.Keywords Automatic sorting of fruits, electrical impedance spectroscopy, nondestructive testing of fruits, post harvest assessment, quality assessment of fruits.

No abstract

No abstract

A capacitive angular position sensor capable of covering 360" is presented. It is made up of four quadrants, each of which consists of a parallel plate capacitor whose higher potential plate (HPP) has a specific shape. A grounded semi-circular plate, whose angular position is measured, moves between these capacitors. When these capacitors are supplied with sinusoidal voltages of mutually shifted phases in a bridge system, the phase of the output voltage of the bridge changes with the mechanical angle. Simulation results show that this relationship can be linearised if the shape of the HPPs is modified. A simple prototype has been developed in which the shaping of the HPPs gives satisfactory improved results. The phase of the output voltage is measured digitally and the relationship between the angular position and the digital output is found to be linear, with a linearity error f0.5% and a resolution of 3 arc minutes.

No abstract