• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.2
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• pp.227-235
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• 2017

In this paper, a systematic 5-mode(road steering, all-wheel steering, crab steering, reduced swing out mode and independent steering) steering algorithm design process for an all-terrain mobile crane with 5 axles and all steerable wheels is proposed. Steering angles for each steering mode are designed based not only on basic theory but also on vehicle specification, design limitation and requirements. A multi-body dynamic analysis is carried out to investigate the feasibility of the steering algorithm. According to the results, the proposed steering algorithm meets the objective of each steering mode.

• Journal of Drive and Control
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• v.14 no.2
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• pp.30-36
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• 2017

This paper presents a sliding mode observer-based fault detection algorithm for steering inputs of an all-terrain crane. All-terrain cranes with multi-axles have several steering modes for various working purposes. Since steering angles at the other axles except the first wheel are controlled by using the information of steering angle at the first wheel, a reliable signal of the first axle's steering angle should be secured for the driving safety of cranes. For the fault detection of steering input signal, a simplified crane model-based sliding mode observer has been used. Using a sliding mode observer with an equivalent output injection signal that represents an actual fault signal, a fault signal in steering input was reconstructed. The road steering mode of the crane's steering system was used to conduct performance evaluations of a proposed algorithm, and an arbitrary fault signal was applied to the steering angle at the first wheel. Since the road steering mode has different steering strategies according to different speed intervals, performance evaluations were conducted based on the curved path scenario with various speed conditions. The design of algorithms and performance evaluations were conducted on Matlab/Simulink environment, and evaluation results reveal that the proposed algorithm is capable of detecting and reconstructing a fault signal reasonably well.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.2
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• pp.95-101
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• 2015

In this paper, we develop a sliding mode control for steering wheel angle control based on torque overlay in order to resolve the problem of previous methods for Electric Power Steering (EPS) systems in the Lane Keeping System (LKS) of autonomous vehicles. For the controller design, we propose a 2nd order model of the electric power steering system in an autonomous LKS. The desired state model is designed to prevent a rapid change of the steering wheel angle. The sliding mode steering wheel angle controller is developed for the robustness of the disturbance. Since the proposed method is designed based on torque overlay, torque integration with basic functions of the EPS system for the steering wheel angle control is available for the driver's convenience. The performance of the proposed method was validated via experiments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.120-124
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• 2003

NVH issue at idle condition is one of the major concerns of Passenger and Commercial Vehicle including Sports Utility Vehicle Especially steering wheel vibration at idle condition is a very complex problem and affected by firing frequency of the engine, stiffness of a steering wheel system and the body to which the steering wheel system is attached. To avoid vibration mode coupling between each system of a vehicle, experimental and analytical method has been used at the pre-prototype stage. The resonance frequency of the body and the frame has been decoupled by CAE and the resonance frequency of steering wheel system has been set in between the 1st bending frequency of body and frame. These Results has been used as design guidelines tot the prototype drawing stage. The experimental verification of tile modified pre-prototype vehicle shows good results of the vibration mode decouple. Modal test of prototype vehicle also confirms the vibration mode decouple between each system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.208-211
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• 2005

This paper describes the development process of steering system for reduce idle vibration through the data level of frequency and sensitivity. High stiffness and light weight vehicle is a major target in the refinement of passenger cars to meet customers' contradictable requirements between NVH performance and fuel economy. The target frequency of the steering system is set by benchmarking of a competitive vehicle and the vibration mode map is used to separate steering column modes from resonance of body structure and engine idle rpm. This paper descirbes the analysis approach process for high stiffness of steering system and the design guideline is suggested about steering column and support system by using mother car at initial design stage. We used a patent map in order to analyze accurately a technical trend and suggested the design process using dynamic damper of steering system considering sensitivity. And we established techniques of analysis on steering system and evaluated the level of accuracy of analysis through correlating the test and analysis results. It makes possible to design the good NVH performance vehicle at initial design stage and save vehicles to be used in tests. These improvements can lead to shortening the time needed to develop better vehicles.

• Journal of Auto-vehicle Safety Association
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• v.15 no.2
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• pp.13-20
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• 2023

This paper presents a fault tolerant control strategy for Steer-by-Wire (SbW) systems. Among many problems to be solved before commercialization of SbW systems, maintaining reliability and fault tolerance in such systems are the most pressing issues. In most previous studies, dual steering motors are used to achieve actuation redundancy. However, relatively few studies have been conducted to introduce fault tolerant control strategies using rear wheel steering system. In this work, an actuator fault in front wheel steering is compensated by active rear wheel steering. The proposed fault tolerant control algorithm consists of disturbance observer and sliding mode control. The fault tolerant control performance of the proposed approach is validated via computer simulation studies with Carsim vehicle dynamics software and MATLAB/Simulink.

• Journal of KSNVE
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• v.8 no.3
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• pp.494-503
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• 1998

In this paper, in order to analyze dynamic characteristics of an automobile steering system consisting of many components, natural frequencies and transfer functions of each component and the total system are found on a FFT analyzer by experiments. Then, the data are transmitted to a commercial package program, CADA-PC. By analyzing the data, the mode shape of each natural frequency and damping values are obtained. Also, the function of a rubber coupling in column and telescoping effects on system are considered. C.A.E commercial programs are used to compare with the results of experiments. For the finite element modeling, I-DEAS is used. Data processing and post processing are operated on NASTRAN and XL, respectively. The ball-bearing and the linkage of shaft with column are modeled by spring element. Stiffness is modified from the results of experiments. The results of those show close agreement. In the mode shape of total system, wheel mode is dominant at lower frequency, while the column mode is main mode at higher. The role of rubber coupling in vibration isolation is clear on mode shape. Telescoping function makes natural frequency of column changed.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.5
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• pp.577-585
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• 2015

This paper deals with development of an autopilot system for leisure yacht based on NMEA 2000 network and android platform. The developed system can operate both for manual steering and automatic navigation mode. In automatic steering mode, after manipulation of commands which are NMEA 0183 sentences by android platform, the developed system translates and sends the packets through NMEA 2000 network. Then the controller which is connected to NMEA 2000 network receives the commands and controls the boat's rudder system automatically. The automatic steering mode is achieved by cooperation of two controllers; one for controlling the rudder system, and the other for controlling the vessel's heading. To control the vessel's rudder and heading angle two PID controllers are developed with an adjustable dead-band gain. Also, in order to eliminate the steady-state error occurred by applying dead-band, an integral controller which specifically supervises the system's behavior inside the dead-band area is developed. In this paper, at the first stage, simulations are accomplished using computer in order to examine the feasibility of the proposed based on simulation results. In the next step, the system on a real hydraulic steering model is implemented and at the end the performance examination by implementing it on a real boat and doing test navigation is executed.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.99-108
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• 2007

The bi-modal tram guided by the magnetic guidance system has two car-bodies and three axles. Each axle of the vehicle has an independent suspension to lower the floor of the car and improve ride quality. The turning radius of the vehicle may increase as a consequence of the long wheel base. Therefore, the vehicle is equipped with the All-Wheel-Steering(AWS) system for safe driving on a curved road. Front and rear axles should be steered in opposite directions, which means a negative mode, to minimize the turning radius. On the other hand, they also should be steered in the same direction, which means a positive mode, for the stopping mode. Moreover, only the front axle is steered for stability of the vehicle upon high-speed driving. In summary, steering angles and directions of the each axle should be changed according to the driving environment and steering mode. This paper proposes an appropriate AWS control algorithm for stable driving of the bi-modal tram. Furthermore, a multi-body model of the vehicle is simulated to verify the suitability of the algorithm. This model can also analyze the different dynamic characteristics between 2WS and AWS.

• Journal of the Korean Society for Railway
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• v.10 no.4
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• pp.444-450
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• 2007

The bi-modal tram guided by the magnetic guidance system has two car-bodies and three axles. Each axle of the vehicle has an independent suspension to lower the floor of the car and improve ride quality. The turning radius of the vehicle may increase as a consequence of the long wheel base. Therefore, the vehicle is equipped with the All-Wheel-Steering(AWS) system for safe driving on a curved road. Front and rear axles should be steered in opposite directions, which means a negative mode, to minimize the turning radius. On the other hand, they also should be steered in the same direction, which means a positive mode, for the stopping mode. Moreover, only the front axle is steered for stability of the vehicle upon high-speed driving. In summary, steering angles and directions of the each axle should be changed according to the driving environment and steering mode. This paper proposes an appropriate AWS control algorithm for stable driving of the bi-modal tram. Furthermore, a multi-body model of the vehicle is simulated to verify the suitability of the algorithm. This model can also analyze the different dynamic characteristics between 2WS and AWS.