• 농업과학연구
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• 제43권1호
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• pp.116-126
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• 2016

The objective of this study is to predict the fuel efficiency of an agricultural tractor. The fuel efficiency of the tractor during rotary tillage was predicted using numerical modeling. A numerical model was developed using Simulation X. Based on tractor power flow, numerical modeling consisted of an engine, transmission, PTO (power take off), and hydraulics. The specifications of major components utilized in the numerical model were the same as those of a 71 kW tractor (field test tractor). The load that was inputted for fuel efficiency prediction into the simulation model was obtained from a field test. Fuel efficiency predictions were conducted by comparing field test results and simulation results. In addition, it was performed by dividing the rotary tillage and steering section. Main results are as follows: first, t-values of engine torque were measured to be 0.31 in the rotary tillage and 0.92 in the steering section. Second, t-values of fuel consumption were measured to be 0.51 and 5.41 in the rotary tillage and the steering section, respectively. Finally, t-values of fuel efficiency were measured to be 1.72 and 40 in the rotary tillage and the steering section, respectively. The results show no significant differences with t-values of less than 5% in the rotary tillage. But, it shows significant differences in the steering section. Therefore, simulation for accurate fuel efficiency prediction requires a suitable algorithm or detailed design of the simulation model in the steering section.

• Journal of Biosystems Engineering
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• 제40권1호
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• pp.19-27
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• 2015

Purpose: A system to measure the visibility of agricultural tractor operators was designed and evaluated according to ISO standards, and a blind area diagram around the tested tractor was created based on the manual method recommended by the National Institute for Occupational Safety and Health (NIOSH). Methods: A visibility measurement system was designed and evaluated based on the ISO 5006 and ISO 5721-1 standards. Two bulbs used to simulate the operator's eyes were mounted on a bar with a supporting frame. A wooden frame was used to determine the seat index point position. The 12-m visibility test circle was divided into six sectors of vision, and the test tractor was placed at the center of the circle. Artificial light was supplied in the darkened environment, and shadow or masking effects were measured manually around the 12-m circle. Results: When the bulbs were placed at the operator's eye level, front visibility was good; no masking was found in the "A" vision sector, but larger masking widths were found in the "B" and "C" vision sectors. Since the masking width exceeded 700 mm, additional tests, such as movement of the light sources to both sides of the operator's eye level, were performed. Less than six masking effects were found in the semi-circle of vision to the front, and more than one masking was found in the "B" and "C" visual fields. The minimum distance between the centers of two masking effects exceeded 2500 mm when measured as a chord on the semi-circle of vision. A blind area diagram was created to define the exact nature of the blind spots and mirror visibility. Conclusions: Visibility evaluation is an effective way to enable proper and safe operation for agricultural tractor operators. Inclusion of this visibility evaluation test in the general testing process might aid tractor manufacturers.

• 드라이브 ㆍ 컨트롤
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• 제19권4호
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• pp.36-45
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• 2022

The aim of this study was to verify an E-driving system of a 44 kW-class electric tractor using agricultural workload data. Workload data were acquired during field test (plow tillage, rotary tillage, loader operation, field driving, asphalt driving) using a conventional tractor with a load measurement system. These workload data were converted to data of a 44 kW-class tractor based on the load factor of the engine. These data were used to verify the design of the E-driving system of an electric tractor. High-load operations such as plow tillage, rotary tillage, and loader operation could be performed at stage L and stage M. High-speed operation (asphalt driving) could be effectively performed at stage H using a rated rotational speed of the motor. As a result, the E-driving system of the electric tractor was possible to perform all major agricultural operations according to gear stages of range shift. Based on results of this research, we plan to develop an electric tractor equipped with an E-driving system and conduct research on actual vehicle verification in the future.

• Journal of Positioning, Navigation, and Timing
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• 제2권2호
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• pp.123-130
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• 2013

Autonomous agricultural machines that are operated in small-scale farmland frequently experience turning and changes in direction. Thus, unlike when they are operated in large-scale farmland, the steering control systems need to be controlled precisely so that travel errors can be minimized. This study aims to develop a control algorithm for improving the path tracking performance of a steering system by analyzing the effect of the setting of the waypoint, which serves as the reference point for steering when an autonomous agricultural machine moves along a path or a coordinate, on control errors. A simulation was performed by modeling a 26-hp tractor steering system and by applying the equations of motion of a tractor, with the use of a computer. Path tracking errors could be reduced using an algorithm which sets the waypoint for steering on a travel path depending on the radius of curvature of the path and which then controls the speed and steering angle of the vehicle, rather than by changing the steering speed or steering ratio which are dependent on mechanical performance.

• Journal of Biosystems Engineering
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• 제34권1호
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• pp.8-14
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• 2009

When a farmer buys a tractor, the power size of a tractor is determined by various factors such as farm size, farmer's age, farming type, topographical area of farm. Relationships between tractor selection and these factors were found. Three regression models were developed to analyze the relationship. Those models were an OLS-1 model (based on 567 samples having tractors), an OLS-2 model, and a Tobit model (both based on the 1,941 samples). Regression analysis results showed that farm size and farmer's age affected selection of power size for all models at an 1% significance level. It was also shown that some farming types also had significant relationships with the tractor power size. Upland cultivating farmers and livestock farmers had larger tractors than rice cultivating farmers, while orchard farmers had smaller tractors. As for the topographical area, only middle area had significant difference with plain area. Farmers who had a rice-transplanter or a combine had larger tractors than those who didn't.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2001년도 동계 학술대회 논문집
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• pp.83-89
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• 2001

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2001년도 하계 학술대회 논문집
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• pp.85-90
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• 2001

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.1267-1268
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• 2011

• 농업과학연구
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• 제38권2호
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• pp.343-347
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• 2011

Precise traveling and tillage operation using an autonomous tractor is difficult with the data from the Geographic Information System(GIS) because it does not include the data of the width and inclination of the field to work. The minimum turing radius of the tractor could be different from the value presented by the tractor maker due to the moisture content of the field soil or operators' skill. Two programs were developed to process data obtained with the tillage path measuring system: one for recognizing coordinates of the 4 field corners, and the other for recognizing the minimum turning radius of the tractor.

• Journal of Biosystems Engineering
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• 제26권6호
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• pp.509-516
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• 2001

This paper introduced some advantages of the time-frequency analysis of vibration and investigated, using the time-frequency transform, the characteristics of the transient motion of a tractor seat, which occurred during the tractor traversed over a rectangular obstacle on the flat surface. The characteristics of the short-time courier and wavelet transforms as time-frequency analysis methods were introduced and discussed to figure out which is more suitable to the analysis of the transient motions of agricultural tractors. Using each transform, transient vibration of a tractor seat was analyzed. Results of the analysis showed that the transient vibration of the seat was influenced by the natural frequencies of vertical mode of chassis, pitching mode of engine and pitching mode of cab of the tractor. The time sequence of the natural mode of tractor vibration was also revealed by the time-frequency analysis. The vibration path analysis by the time-frequency transform showed that the vibration energies transmitted from the front mounts to the seat were less than those from the rear mounts. The energy reduction ratios between the cab mounts and seat were also estimated to be about 72∼78%. The front mounts showed larger reduction than the rear mounts. However, the reduction difference between the right and left sides mounts was negligibly small. The short time Fourier transform was found to be a proper method for investigating the transient motions of farm machines and their effects on the ride vibration.