• 한국공작기계학회논문집
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• 제14권3호
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• pp.81-86
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• 2005

The agricultural working tractor of this study is equipped with 4 wheel driving system developed in study 1 and 4-type wheel steering system. The wheel steering system has four type of steering methods that are front wheel steering, rear wheel steering, 4 wheel steering with opposite phase, and 4 wheel steering with corresponding phase. This study introduces the hydraulic circuit of the 4-type wheel steering system and the construction of working tractor. Judging from the field test results of the developed working tractor, it is apparent that 4-type wheel steering system has many advantages when driving in a narrow corral.

• 한국기계가공학회지
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• 제3권3호
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• pp.71-78
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• 2004

The loader of this study is an agriculture machine for a stock farmer. We has much researched about power train and steering system in order to develop a new stock machine. So, the loader developed in this study has a 4 wheel driving system and a 4-type wheel steering system. Though the technological region is some large and general, these technologies are very important and their technical life may be very long. The power train of the loader is consisted of many units as follows, engine, clutch, transmission, and axles. And, the 4-type wheel steering system is consisted of oil tank, oil pump, steering valve, solenold valve, electronic controller, hydraulic cylinders, and touch sensors. This study shows construction logics of power train and steering system. We could know from many working tests that the developed loader with 4-type steeling system has many advantages when driving in a narrow corral.

• 한국공작기계학회논문집
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• 제14권1호
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• pp.66-72
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• 2005

The working tactor of this study, an agriculture machine, is consisted of 4 wheel driving system with gear trains and 4-type wheel steering system. Since technological regions for 4 wheel driving system and 4-type wheel steering system are some large, we divide on two studies on 4 wheel driving system and 4-type wheel steering system This study develops transmission and axle that are very important units for strong working operation because the power of tractor is largely affected by transmission and axle. Even if the development of the power train is some common technology, it is very complicated work and needs many experience know-hows. So, for new given specifications fitted to the working tractor, a kind of new agriculture machine, this study haws out processes that are development of assembly drawing and strength analysis through classical method and CAE software for all internal parts and housing cases.

• 한국자동차공학회논문집
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• 제3권3호
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• pp.66-78
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• 1995

In this paper, we address vehicle modeling and dynamic analysis of four wheel steering systems (4WS). 4WS is one of the devices used for the improvement of vehicle maneuverability and stability. All research done here is based on a production vehicle from a manufacturer. To study actual system response, a three dimensional, full vehicle model was created. In past research of this type, simple, two dimensional, bicycle vehicle models were typically used. First, we modelled and performed a dynamic analysis on a conventional two wheel steering(2WS) vehicle. The modeling and analysis for this model and subsequent 4WS vehicles were performed using ADAMS(Automatic Dynamic Analysis of Mechanical Systems) software. After the original vehicle model was verified with actual experiment results, the rear steering mechanism for the 4WS vehicle was modelled and the rear suspension was changed to McPherson-type forming a four wheel independent suspension system. Three different 4WS systems were analyzed. The first system applied a mechanical linkage between the front and rear steering mechanisms. The second and third systems used, simple control logic based on the speed and yaw rate of the vehicle. 4WS vehicle proved dynamic results through double lane change test.

• 한국생산제조학회지
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• 제8권1호
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• pp.150-157
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• 1999

In this study, the loader was completed that has 4-wheel gear driven drivetrain of study (Ⅰ), the 4-wheel steering with power wheel type, all-wheel traction system, and joy-stick type lever for hydraulic control valve. From driving test of the developed 4WD and 4WS type loader, we obtained that the minimum circling radius and the necessary width in circling motion reduced about 40% and 33% compared with 2WS type loader. Also, all-wheel traction system could keep the tires glued to the ground with greater stability, the power steering allowed a smoother operation, and the joy-stick type lever offered easily to control. Thus, the developed loader having these functions was very fit in a small cattle shed or rugged ground.

• 대한의용생체공학회:의공학회지
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• 제38권4호
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• pp.197-204
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• 2017

The aim of this study was to evaluate driving performance of normal subjects for controlling the steering wheel by using foot operated steering devices in the driving simulator. Many people with complete bilateral loss or loss of use of upper limbs but with normal lower limbs are frequently left without use and/ or control of their hands, arms, or the upper extremities of their bodies. As a result, persons disabled in this manner have problems in operation an automobile because they cannot grasp and manipulate a conventional steering wheel. Therefore, if foot operated steering devices are used for controlling the vehicle on in people with disabilities, the disabled people could improve their community mobility by driving a car safely. Ten normal subjects were involved in this research to evaluate steering performance by using three types of steering devices(conventional steering wheel, pedal type foot steering, circular type foot steering) in driving simulator. STISim Drive 3 program was used for testing the driving performance in two road scenarios: straight road and curved road at low and high speed of vehicle (40 km/h and 80 km/h). This study used two-way ANOVA to compare the influences of two factors(type of foot steering device and road scenario) in the three dependent variables of steering performance(standard deviation of lateral position, the lateral position of vehicle and the number of line crossing). The average values of the three dependent variables(standard deviation of lateral position, lateral position and the number of line crossing) of driving performance were significantly smaller for conventional steering wheel or pedal type foot steering than circular type foot steering.

• 한국생산제조학회지
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• 제7권6호
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• pp.141-148
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• 1998

A loader is construction & road or agricultural machinery for lifting, moving, and mixing. This study deals with the agricultural mini loader for stock raising farming. The performance of the machine is established by pulling power, working lifting capacity, and minimum circling radius, etc. Also, driving easiness and endurance are very important in manufacturing. Thus, this study has developed the loader with the 4-wheel driving equipment by gear transmission, the 4-wheel steering equipment by power handle steering type, and the equipment making four wheels touch simultaneously on the rugged ground. The developed loader having these functions was very fit in a small cattle shed or a rugged ground. This study is divided into two parts; (I) development of 4WS transmission and (II) construction of the loader by 4WS system and other equipments.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.39-51
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• 1996

In the turning maneuver of the vehicle, its motion is mainly dependent on the genuine steering characteristics in view of the directional stability for stable turning ability. The under steer vehicle has an ability to maintain its own directonal performance for unknown external disturbances to some extent. From a few years ago, in order to acquire the more enhanced handling performance, some types of four wheel steering vehicle were considered and constructed. And, various rear wheel control logics for external disturbances has not been suggested. For this reason, in this posed rear wheel control logic is based on the yaw rate feed back type and is slightly modified by an yaw rate tuning factor for more stable turning performance. And an external disturbance is defined as a motivation of the additional yaw rate in the center of gravity by an uncertain input. In this study, an external disturbance is applied to the vehicle as a form of the additional yawing moment. Finally, the proposed rear wheel control logic is tested on the multi-body analysis software(ADAMS). J-turn and double lane change test are performed for the validation of the control logic.

• 유공압시스템학회논문집
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• 제7권4호
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• pp.9-14
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• 2010

Most power steering systems work by using a hydraulic system to turn the vehicle's wheels. The pressure is usually provided by a hydraulic pump driven by the vehicle's engine. A double-acting hydraulic cylinder applies a force to the steering gear, which in turn applies a torque to the steering axis of the road wheels. The flow to the cylinder is controlled by valves operated by the steering wheel ; the more torque the driver applies to the steering wheel and the shaft it is attached to, the more fluid the valves allow through to the cylinder, and so the more force is applied to steer the wheels in the appropriate direction. Since the pumps employed are of the positive displacement type, the flow rate they deliver is directly proportional to the speed of the engine. And for a long time, the type of hydraulic pump pulley was boss welding type. But recently, monolith type driving pulley is widely used. Therefore in this paper we studied the safety of monolith type driving pulley to the extracting force and endurance by FEM analysis and experiments.

• 산업경영시스템학회지
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• 제29권4호
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• pp.1-7
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• 2006

This study determined the optimal positions of the movable steering wheel and pedal systems of industrial vehicle by various body dimensions. The position of objects and starting driving posture were measured by Martin-type anthropometer and goniometer. The X, Y and Z axis of movable steering wheel and pedal systems were measured horizon distance from right side to left side, horizon distance from front side to rear side and vertical distance from floor to ceiling. During the experiment in order to exclude learning effectiveness with forklift driving, 27 subjects who had male not experiences in driving a forklift used in the experiment. The relationship between the position of steering wheel and driver's posture with body dimensions was analyzed by using correlation relation and paired comparison t-test based on the measured data. The pedal location in X and Z axises was not related with various body dimensions. Also, the steering wheel was different among the angles of the right elbow and shoulder depending on the various body dimensions.