Development of a self-leveling system for the bucket of an agricultural front-end loader using an electro hydraulic proportional valve and a tilt sensor

Abstract

A front-end loader (FEL) mounted on an agricultural tractor is one of the most commonly used implements for farm work. However, when the tractor carries material using the bucket attached to the FEL on a sloping ground, the materials can spill or roll back over the operator due to the tilted body, thereby requiring the bucket surface to remain level at a constant value regardless of varying slopes. In this study, an active system for controlling the angle of the FEL bucket on a tractor based on the real-time measurement of ground slopes was developed to enable the bucket to constantly remain level. A FEL simulator operated based on an electro hydraulic proportional valve (EHPV) was constructed in the laboratory to develop a proportional-integral-derivative (PID) controller forming a virtual electronic control unit (ECU) on the computer, which could automatically adjust the bucket angles depending on varying input angles while sending SAE-J1939 associated messages via CAN BUS to the EHPV. The different parameter values for the PID controller due to the gravity effect of the bucket were determined using a manual PID tuning method while assuming that the tractor travels on either an ascending slope or a descending slope. The developed PID control-based self-leveling system showed a mean of steady-state errors of within 1° and a mean of delayed times of ~ 0.8s when the step input of +20° was given, implying that the developed system and control algorithm would be effective in maintaining the bucket angle at a certain value. Future studies include the improvement of the control algorithm to reduce such a time delay as well as the application of the developed algorithm to the FEL mounted on a tractor tested at a testing ground.

Experimental Structural Safety Analysis of Front-End Loader of Agricultural Tractor

“…S y σ max (2) where S.F. is static safety factor, S y is tensile yield strength of the material, MPa, and σ max is measured maximum normal stress during the operation, MPa.…”

“…Various implements have been mounted on prime movers to improve the efficiency and productivity of agricultural work [1]. Among them, the front-end loader is attached to the front of the agricultural tractors and controlled through tractor hydraulic systems to transport soil, agricultural products, and byproducts [2,3]. The front-end loader can fail or become deformed under large loads when it performs loading or unloading and is exposed to irregular road surfaces or obstacles due to the nature of the working environment [4,5].…”

Evaluation of Hydraulic Characteristics of Electrohydraulic Proportional Valve (EHPV) for an Auto-Steering Tractor Application

“…Research on EHPVs employed in agricultural machinery has been performed by several researchers around the world. These works include studies on the major tractor components such as a front loader [13], the power shuttle system [14], the hitch controller [15,16], and the transmission [17]. Most related studies focused on the development of valve control algorithms.…”

A Model of an Extending Front Loader

“…An important aspect of the safe operation of a front loader is the self-leveling of the working tool. For this purpose, active systems are used to control the angle of inclination of the front loader's working tool based on real-time measurement of the terrain inclination using a simulation based on an electro-hydraulic proportional valve [12]. Supervisory systems and dedicated control algorithms are also being developed [13].…”