Design and testing of a fuzzy logic based seeding depth control system

The control system in this research utilizes a microprocessor-based fuzzy logic control process in combination with a novel seeding depth gauge system. The fuzzy algorithm is modelled upon expert human control by means of linguistic variables that describe the error between the measured seeding depth and the desired depth set point. Three scenarios were examined: a 3-membership function, a 5-membership function, and a 7-membership function fuzzy control algorithm. The 5-membership function algorithm was found to provide the best combination of control and complexity for this application. Two controller units were constructed using the Motorola MC68HC16Z1 microprocessor unit as the main controller, for testing in laboratory simulations and under field conditions. The 3-membership function algorithm was tested under field conditions. Data was logged from the field trials, with error mean from the set point being 2 mm, with variation and standard deviation being 17.1 cm and 2.8 cm, respectively, based on converted A/D readings.