design, development and evaluation of an automatic blade depth controller system for a laser-guided land-leveler

excessive cutting depth during leveling of agricultural land increases power needed by the tractor drawbar and will result in undesirable slippage and excessive strain on the tractor engine.  the result of sustained excess will be the break-down of the tractor. an auxiliary blade depth controller to prevent overloading during leveling was designed, fabricated and evaluated in this study. the system consists of a closed loop that obtains the real tractor engine speed using a dynamo and compares the critical and desired speeds of the engine as controlled by the user by means of a manual keyboard. the data is recorded in the main microcontroller memory and displayed online on a lcd. the system governing the blade depth prevents attainment of critical engine speed that will cause overloading. the depth controller system overrides manual control and sends pulses to the solenoid valve to adjust the blade depth cylinder to decrease the depth of excavation until the desired engine speed is attained. after eliminating the risk of overload, the system switches blade command back to the laser control box. the system was evaluated on a laser-guided land leveler on farmland. fuel consumption and field performance of the machine were determined with and without use of the proposed control system. the test was carried out using a t-test with five replications. the result demonstrated a significant difference at 5% probability for use of the proposed system (p < 0.05). the new system decreased fuel consumption 18.4% and increased field performance 19.7%, which makes it an effective cost-saving measure.