• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.1
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• pp.63-71
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• 2000

A shift control algorithm of a newly developed two-speed gear shift system is proposed for electric vehicle applications. The algorithm is formulated according to the motor torque map and optimized to obtain the adequate propulsion characteristics for vehicle. Two speed gear system with shift control algorithm has proved greater efficiencies in terms of energy economy with its simplified hardware and software structures. The gear shifting is designed to be carried out by an actuator and the control signal from a vehicle control unit equipped with $\mu$-processor. The results of performances and efficiency of the algorithm by simulation and vehicle test are described.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.639-645
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• 2011

Wheel-loader is a construction vehicle for uploading soil or sand into truck and transportation of materials, which requires large driving power and high rotational speed. To improve the working efficiency, the operator has to shift gears and control levers for bucket & boom simultaneously. Therefore, the automatic transmission has been introduced to enhance operator's convenience and enable effective operation. To develop the automatic transmission for the wheel-loader, technologies such as gears and a clutch-pack design and shift algorithm are required for improvement of shift quality. In this paper, the shift algorithm for the wheel-loader was developed and its shift pattern was analyzed. As the shift control is affected by the pressure profile for the clutch control, the shift quality depending on the pressure profile has been evaluated using experiment and simulation model analysis.

• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.2
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• pp.7-20
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• 2007

TCU is a shift controller far automatic transmission of which major functions are to determine the shift point and manage the shifting process based on the various input signals. As the recent digital control technologies advance, it plays a key-role to improve a transmission performance and its algorithm becomes more complicated. This paper describes the development of transmission simulator fur wheel loader that enables a TCU for normal stand-alone operation by the real-time emulation of TCU interface signals. It can be utilized for the analysis of shift control algorithm implemented in a commercial TCU as well as for the development of brand new TCU.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.129-130
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• 2007

• Journal of Drive and Control
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• v.20 no.4
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• pp.17-26
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• 2023

A forklift is an industrial vehicle that lifts or transports heavy objects using a hydraulically operated fork, and is equipped with an automatic transmission for the convenience of repetitive transportation, loading, and unloading work. The Transmission Control Unit (TCU) is a key component in charge of the shift control function of an automatic transmission. It consists of an electric circuit with an input/output signal interface function and firmware running on a microcontroller. To develop TCU firmware, the development process of shifting algorithm design, firmware programming, verification test, and performance improvement must be repeated. A simulator is a device that simulates a mechanical system having dynamic characteristics in real time and simulates various sensor signals installed in the system. The embedded transmission simulator is a simulator that is embedded in the TCU firmware. information related to the mechanical system that is necessary for TCU normal operation. In this study, an embedded transmission simulator applied to the originally developed forklift TCU firmware was designed and used to verify various forklift shift control algorithms.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3849-3855
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• 2012

This paper describes a control algorithm and test results of an automated manual transmission clutch actuated by a stepping motor. The control algorithm extracts driver's demand from CAN signals and decides the exact timing to engage or disengage the clutch based on the demand. A pulse signal is generated to drive the clutch and the travel of the clutch can be calculated by accumulating the pulse signal. An auto code generation method was introduced in implementing the control logic to the micro-processor of the prototype controller and a series of basic tests were carried out to validate its performance.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.100-109
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• 2000

In this paper a stepping motor drive electronic ratio control system for a metal belt CVT is suggested. The electronic ratio control system developed in this study is designed to control flow rate which is required to obtain the shift speed and to control the primary actuator pressure to maintain the desired ratio. Considering these control characterstics a fuzzy logic is used for the CVT ratio control. Using the fuzzy logic dynamic models of the ratio control system is investigated and compared with the experimental results. The experimental and simulation results show that the electronic ratio control system developed in this study can be used in CVT system for the active control of the speed ratio.

• Journal of Drive and Control
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• v.15 no.4
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• pp.30-38
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• 2018

Electronic control units (ECUs) are currently popular, and have evolved further towards the high-end application of autonomous vehicles in the automotive industry. Such digital technologies have also become widespread, in agriculture and construction equipment. Likewise, transmission control of high-speed tracked vehicles is based on the transmission control unit (TCU), performing complex gear change control functions, and diagnostic algorithms (a TCU's self-diagnostic and reporting capability of malfunction data through CAN communication). Since all functions of TCU are implemented by embedded-software, it is hardly possible to analyze specifications by reverse engineering. In this paper a real-time transmission simulator adaptable to TCU is presented, for analysis of diagnosis algorithm and standards. Signal simulation circuits are deliberately designed considering electrical characteristics of TCU inputs and various analysis tools, such as analog input auto scan function, and global output enable switch, are implemented in software. Test results from hardware-in-the-loop simulator verify tolerance time for each error, as well as cause of fault, error reset conditions.

• Journal of Drive and Control
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• v.17 no.3
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• pp.47-56
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• 2020

As a shift control of automatic transmission was managed with the electronic control unit (ECU), shift quality which is a measure of shift shock during gear change has markedly improved. However, the initial clutch pressure control of the clutch filling phase should continue to rely on the predetermined control input since the input and output speeds are unchanged until the shifting process attains the inertia phase. It is critical to minimize the clutch response time and control the clutch pressure accurately at the end of clutch fill to achieve quick shift response and smoothness. Advanced transmission companies have adopted an auto calibration method which establishes the databases for the clutch piston fill-up attributes and the frictional characteristics of the disks. In this study, a distinctive auto calibration algorithm for forklift transmission under development is proposed and verified with the real-vehicle test. The experimental calibration results showed consistent turbine dynamics at the initial stage of shifts with the properly calibrated clutch-fill control parameters. By using this technique, it is necessary to finalize the shift control for the various operation conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.86-96
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• 1997

In this paper, engine-CVT consolidated control algorithm was developed. Engine -CVT control strategy suggested uses throttle control based on power difference and CVT ratio control based in CVT ratio map. Simulation results showed that the larger the rate of CVT ratio, the better the engine performance in the optimal operation line. Also, it was found that the engine performance where the magnitude of the acceleration changes abruptly depends on the magnitude of the rate of CVT ratio. Comparing the results of CVT control only without engine control, the engine-CVT control algorithm suggested in this work showed better performance demonstrating that the consolidated control algorithm should be required for the engine optimal operation.