• The Journal of Korea Robotics Society
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• v.18 no.3
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• pp.299-307
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• 2023

In the midst of accelerating wars around the world, unmanned robot technology that can guarantee the safety of human life is emerging. ERP-42 is a modular platform that can be used according to the application. In the field of defense, it can be used for transporting supplies, reconnaissance and surveillance, and medical evacuation in conflict areas. Due to the nature of the military environment, atypical environments are predominant, and in such environments, the platform's path followability is an important part of mission performance. This paper focuses on reducing the minimum turning radius in terms of improving path followability. The minimum turning radius of the existing 2WS/2WD in-wheel platform was reduced by increasing the torque of the independent driving in-wheel motor on the rear wheel to generate oversteer. To determine the degree of oversteer, two GPS were attached to the center of the front and rear wheelbases and measured. A closed-loop speed control method was used to maintain a constant rotational speed of each wheel despite changes in load or torque.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.4
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• pp.26-31
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• 2005

ITR(Inne. Tie Rod) is one of the core parts in an automobile steering system. The front wheels are connected to the steering system, which are controlled by steering wheel through the ITR. Improvement of assembling ITR is needed f3r drivers' satisfaction. Therefore, the parameters influencing the rotational torque were studied and analyzed. The useful results can be obtained, and could be applied to manufacture ITR. Through these manufacturing technologies, high quality ITR have been manufactured with high productivity.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.409-414
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• 2007

Nowadays, with the advancement of computational mechanics, and vehicle dynamics simulation linked up with virtual testing laboratory(VTL) and virtual proving ground(VPG) technologies has become a useful method for analyzing numerous driving performances and diverse noise/vibration characteristics. In this paper, the analytical vehicle model based on multi-body dynamics theory was developed to investigate the vibration characteristics according to various road conditions. For the purpose, the whole vehicle parameters, each vehicle's part parameter, and part connecting elements such as spring, damper, and bush were measured by an experiment. Also, the vehicle dynamics model, which includes the front suspension, rear suspension, steering, front wheel, rear wheel, and body subsystems has been constructed for computer simulation. With the developed vehicle dynamics model, three forces and three moments measured at each wheel center were applied to evaluate and analyze dynamics and vibration characteristics for miscellaneous road conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1276-1283
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• 2006

This study proposes two ESP systems which are designed to enhance the lateral stability of a vehicle. A BESP uses an inner rear wheel braking pressure controller, while a EBESP employs an inner rear wheel and front outer wheel braking pressure controller. The performances of the BESP and EBESP are evaluated for various road conditions and steering inputs. They reduce the slip angle and eliminate variation in the lateral acceleration, which increase the controllability and stability of the vehicle. However EBESP enhances the lateral stability and comfort. A driver model is also developed to control the steer angle input. It shows good performances because the vehicle tracks the desired lane very well.

• Journal of the Korea Convergence Society
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• v.3 no.4
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• pp.35-44
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• 2012

In this study, a simulation program is developed in order to investigate non steady-state cornering performance of 6WD/6WS special-purpose vehicles. 6WD vehicles are believed to have good performance on off-the-road maneuvering and to have fail-safe capabilities. But the cornering performances of 6WS vehicles are not well understood in the related literature. In this paper, 6WD/6WS vehicles are modeled as a 18 DOF system which includes non-linear vehicle dynamics, tire models, and kinematic effects. Then the vehicle model is constructed into a simulation program using the MATLAB/SIMULINK so that input/output and vehicle parameters can be changed easily with the modulated approach. Cornering performance of the 6WS vehicle is analyzed for brake steering and pivoting, respectively. Simulation results show that cornering performance depends on the middle-wheel steering as well as front/rear wheel steering. In addition, a new 6WS control law is proposed in order to minimize the sideslip angle. Lane change simulation results demonstrate the advantage of 6WS vehicles with the proposed control law.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.76-85
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• 1997

The understeer characteristics of four wheel steering system(4WS system) in a high speed region have a negative effect upon the yaw velocity, leading to a decrease in the handling ability of vehicle. As a result, even if the side slip angle of vehicle can be kept up a minimum, a driver must compensate a decrease in yaw velocity by increasing the steering wheel angle in order to track the desired vehicle path. In this study, to keep the side slip angle of vehicle at zero and achieve a suitable yaw velocity in vehicle motion, a full active 4WS system(FA 4WS system) with actively steerable front and rear wheels is presented based on a nonlinear vehicle model and a model following control of yaw velocity. And the analysis results show the fat that, besides the excellent stability of vehicle, the FA 4WS system is able to realize better handling performance of vehicle than the previous 4WS systems in the high speed region.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.34-42
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• 2006

As many systems depend on electronics, concern for fault tolerance is growing rapidly. For example, a car with its steering controlled by electronics and no mechanical linkage from steering wheel to front tires(steer-by-wire) should be fault tolerant because a failure can come without any warning and its effect is devastating. In order to make system fault tolerant, there has been a body of research mainly from aerospace field. This paper presents the structure of predictive smoothing voter that can filter out most erroneous values and noise. In addition, several numerical simulation results are given where the predictive smoothing voter outperforms well-known average and median voters.

• International Journal of Control, Automation, and Systems
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• v.6 no.1
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• pp.126-134
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• 2008

As many systems depend on electronics, concern for fault tolerance is growing rapidly. For example, a car with its steering controlled by electronics and no mechanical linkage from steering wheel to front tires (steer-by-wire) should be fault tolerant because a failure can come without any warning and its effect is devastating. In order to make system fault tolerant, there has been a body of research mainly from aerospace field. This paper presents the structure of predictive hybrid redundancy that can remove most erroneous values. In addition, several numerical simulation results are given where the predictive hybrid redundancy outperforms wellknown average and median voters.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.248-251
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• 2004

Stability of truck and trailer are the most significance in Thai automotive industry. This paper presents the mathematical model of a six-degree-of-freedom semi-trailer vehicle. Search method was implemented to obtain the optimum design variables of the trailer which are the distance from the fifth wheel to the centroid of the trailer and the distance from the centroid of the trailer to the trailer axel. The objective function is to minimize the steady side slip velocity, steady-state yawing velocity and steady-state angle between the tractor and the trailer. From the calculation , the optimum distance from the fifth wheel to the centroid of the trailer and the optimum distance from the centroid of the trailer to the trailer axle are 5.50 and 3.25 meters respectively. The stability of the optimal semi-trailer vehicle was also examined in steady state. The steady side slip velocity, yawing velocity and the angle between tractor and trailer are also obtained using linearization technique under unit step disturbance of the tractor front wheel steering angle.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.3
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• pp.13-19
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• 2012

The fatalities rate for passenger vehicles, vans, and commercial vehicles is 1.23, 1.90 and 2.46 deaths per 10,000 registered vehicles, respectively. This shows that vans and commercial vehicles are vulnerable compare to passenger vehicles. To evaluate the crashworthiness of van and Light Truck Vehicle(LTV), we carried out frontal offset crash test at 64km/h, 40% overlap as per IIHS(Insurance Institute for Highway Safety). The test result show that LTV is very poor to protect occupant at frontal crash cause there is no safety system such as airbag and pretensioner and front end length(distance from front bumper to steering wheel) is short. One of the van rated as the lowest rating even it is equipped with airbag, cause its safety cage was collapsed during the test. This result shows that the structural integrity is very important in terms of occupant protection.