PID control for sprayer sections under laboratory conditions

H. Karadöl¹, S. Arslan²* and A. Aybek³

¹Kahramanmaraş Sütçü İmam University, Graduate School of Natural and Applied Sciences, Department of Biosystems Engineering, TR 46100 Kahramanmaraş, Turkey
²Uludağ University, Faculty of Agriculture, Department of Biosystems Engineering, TR 16059 Bursa, Turkey
³Kahramanmaraş Sütçü İmam University, Faculty of Agriculture, Department of Biosystems Engineering, TR 46100 Kahramanmaraş, Turkey
*Correspondence: sarslan@uludag.edu.tr

Abstract:

The objective of this study was to develop and test a PID controller to adjust the height of bum sections of sprayer booms. This study was conducted under laboratory conditions using an experimental frame representing the boom sections of the sprayer. The boom section was operated using an electro-hydraulic system driven by a hydraulic power pack. Ultrasonic distance sensors were used to adjust the height of the boom tips based on the set height values. During the on-off control, the sudden openings of the hydraulic valve conduits caused oscillations, resulting in unstable operation. In the PID control, increased gain up to 100% resulted in unstable operations and resembled the response of on-off control. With the use of low gain values, oil flow delivered to the hydraulic actuator was adjusted accurately using the proportional valves and smoother boom section motion was possible. The effects of different disturbances on the system dynamic responses were presented graphically using PID control.

Key words:

Development of an active boom controller for field sprayers

H. Karadöl¹ and S. Arslan²

¹Kahramanmaraş Sütçü İmam University, Graduate School of Natural and Applied Sciences, 46100, Kahramanmaraş, Turkey
²Kahramanmaraş Sütçü İmam University, Biosystems Engineering Department, 46100 Kahramanmaraş, Turkey,
e-mail: sarslan@ksu.edu.tr

Abstract:

The objective of this study was to develop an electronic control system to automatically control the boom of an agricultural sprayer. This paper addresses the electronic circuits and programmes used to accomplish active boom control under laboratory conditions. The boom sections were mounted on two sides of the frame in the laboratory and ultrasonic sensors were placed at the tips of boom sections. The sensors were tested at varying heights from 50 cm to 150 cm to obtain a
calibration equation correlating voltage output of the sensors to the boom
height. In the lab experiments, the calibration of the ultrasonic distance
sensors could be done with a high coefficient of determination (R²=0.999).
Both PLC and PIC programming were used to develop the
control programmes. The simulations of control programs were written in
PIC C and Ladder programming languages and were executed on a computer. The
sensor data were interpreted with the control programme loaded on the control
device and automatically controlled the hydraulic valves and cylinders. The
control program was programmed to neglect vertical oscillations with magnitudes
less than 3.5 cm
under laboratory conditions, which can be varied for field conditions. It was
concluded that PLC and PIC circuits could work fast enough to sample analogue
signals generated by the sensors at a forward speed of 6-8 km/h when used in real
field conditions. Further research is ongoing to adapt the system to a field
sprayer for field experiments.

Key words:

active boom control, electro-hydraulic control, field sprayer, sensors