A Laboratory Study of Ultrasonic Sensors to Determine Position and Orientation of Mobile Robots for Greenhouse Applications



In recent years many researches are carried out to develop robots for agricultural applications. One of the main steps in agricultural robot fabrication is the generation of guidance signals. The objective of this research was a feasibility study of ultrasonic sensors in generating guidance signals to determine the position and orientation of a mobile robot for greenhouse applications. A series of experiments were performed to evaluate the accuracy of the ultrasonic sensors to determine the most applicable arrangement of sensors around the chassis of a robot. The most suitable detected distance ranges of the sensors were 15 to 200 cm. In distances less than 15 cm and angles more than 30 degrees the accuracy was found as low. The maximum width of view of the sensors for flat reflected objects was 17.15 and for curved objects 33.20 cm. The final arrangement of sensors was found out too. Experimental results proved that one can use ultrasonic sensors for generating guidance signals of robot inside greenhouses. With the designed averaging algorithm, one can calculate the lateral and heading errors for corrected data of ultrasonic sensors. Also, in comparison with reference sensors, the maximum error and RMSE for positions were 3 and 0.714 cm and for orientation they were 11.23 and 4.036 cm, respectively