• Journal of Mechanical Science and Technology
• /
• 제16권3호
• /
• pp.283-291
• /
• 2002

The paper demonstrates the tracking performance of a sliding horizon feedback/feedforward preview optimal control when applied to a hydraulic motion simulator which has been built to provide a means of replicating the actual ride dynamics of an automobile seat/human system. The design was developed by solving an ordinary differential equation problem instead of a Ricatti equation. Simulation results indicate that the proposed technique has good performance improvement in phase tracking when compared to the classical design methods. It is also found that the controller can be adjusted more easily for robustness due to more tuning parameters.

• Journal of Mechanical Science and Technology
• /
• 제20권12호
• /
• pp.2052-2060
• /
• 2006

The wear of engine valve and seat insert is one of the most important factors which affect engine performance. Because of higher demands on performance and the increasing use of alternative fuel, engine valve and seat insert are challenged with greater wear problems than in the past. In order to solve the above problems, a simulator was developed to be able to generate and control high temperatures and various speeds during motion. The wear simulator is considered to be a valid simulation of the engine valve and seat insert wear process with various speeds during engine activity. This work focuses on the different degrees of wear at three different singular test speeds (10 Hz, 25 Hz & multi-Hz). For this study, the temperature of the outer surface of the seat insert was controlled at 350$^{\circ}C$, and the test load was 1960 N. The test cycle number was $6.0{\times}10^6$. The mean ($\pm$standard error) wear depth of the valve at 10 Hz and 25 Hz was 45.1 ($\pm$3.7)$\mu$m and 81.7 ($\pm$2.5)$\mu$m, respectively. The mean wear depth of the seat insert at 10 Hz and 25 Hz was 52.7 ($\pm$3.9)$\mu$m and 91.2 ($\pm$2.7)$\mu$m, respectively. In the case of multi-Hz it was 70.7 ($\pm$2.4)$\mu$m and 77.4 ($\pm$3.8)$\mu$m, respectively. It was found that higher speed (25 Hz) cause a greater degree of wear than lower speed (10 Hz) under identical test condition (temperature, valve displacement, cycle number and test load). In the wear mechanisms of valves, adhesive wear, shear strain and abrasive wear could be observed. Also, in the wear mechanisms of seat inserts, adhesive wear, surface fatigue wear and abrasive wear could be observed.

• 한국자동차공학회논문집
• /
• 제11권6호
• /
• pp.14-20
• /
• 2003

The minimization of valve and seat insert wear is a critical factor in the pursuit of engine performance improvement. In order to achieve this goal, we have developed a new simulator, which can generate and control high temperatures up to $900^{\circ}C$ and various speeds up to 80Hz during motion, just like an actual engine. The wear simulator is considered to be a valid simulation of the engine valve and seat insert wear process with various speeds during engine activity. The objective of this work focuses on the different degrees of wear from two different test speeds (10Hz & 25Hz). For this study, the temperature of the outer surface of the seat insert was controlled at $350^{\circ}C$, the cycle number was 2.1$\times$106, and the test load was 1960N. The wear depth and surface roughness were measured before and after the testing using a confocal laser scanner. It was found that a higher speed (25Hz) causes more wear than a lower speed (10Hz) under identical test conditions (temperature, cycle number and test load). In the wear mechanism adhesive wear, shear strain and abrasive wear could be observed.

• 한국정밀공학회지
• /
• 제25권6호
• /
• pp.108-115
• /
• 2008

The wear on engine valve and seat insert is one of the most important factors affecting engine performance. The engine valve and seat insert must be able to withstand the severe environment that is created by: high temperature exhaust gases generated while the engine is running, rapid movement of the valve spring, high pressure generated in the explosive process. In order to study such problems, a simulator has been developed to generate and control high temperatures and various speeds during motion. The wear simulator is considered to be a valid simulation of the engine valve and seat insert wear process with various speeds during engine activity. This work focused on the test of various degrees of wear on four different exhaust valve materials such as HRV40, HRV40-FNV (face nitrided valve), STL #32, STL #6,. Throughout all tests performed in this study, the outer surface temperature of the seat insert was controlled at $350^{\circ}C$, the cycle number was $4.0{\times}10^6$, the test load was 6860 N, the fuel was LPG the test speed was 20 Hz (2400 RPM) and the seat insert material was HVS1-2. The mean (standard deviation) maximum roughness of the exhaust valve and seat insert was $25.44\;(3.16)\;{\mu}m$ and $27.53\;(3.60)\;{\mu}m$ at the HRV40, $21.58\;(2.38)\;{\mu}m$ and $25.94\;(3.07)\;{\mu}m$ at the HRV40-FNV, $36.73\;(8.98)\;{\mu}m$ and $61.38\;(7.84)\;{\mu}m$ at the STL #32, $73.64\;(23.80)\;{\mu}m$ and $60.80\;(13.49)\;{\mu}m$ at the STL #6, respectively. It was discovered that the maximum roughness of exhaust valve was lower as the high temperature hardness of the valve material was higher under the same test conditions such as temperature, test speed, cycle number, test load and seat insert material. The set of the HRV40-FNV exhaust valve and the HVS1-2 seat insert showed the best wear resistance.

• 재활복지공학회논문지
• /
• 제8권1호
• /
• pp.1-7
• /
• 2014

본 연구에서는 기존의 시/청각 방식의 운전정보 전달체계의 한계를 극복하고 더불어 교통약자들의 운전 수행에 도움이 되는 자동차용 햅틱시트 기술을 개발하고자 하였다. 이를 위해 동전형 모터 30개를 사용한 진동자극용 시트커버형 시제품과 모터드라이버모듈을 제작하였고 촉각이상이 없는 젊은 남녀 10명을 대상으로 6자유도 모션베이스 상에 구축된 가상운전 시뮬레이터를 사용하여 가상운전상황에서의 시트진동자극에 대한 실험을 진행하였다. 모터의 동작전압(1.5V, 2.5V, 3.5V)에 따라 세기가 가변되는 30개소의 진동자극의 위치별 인지율을 측정하여 분석하였다. 피험자들은 2.5V,3.5V로 동작하는 30개소의 모터 진동자극을 모두 인지하였고 최저작동전압인 1.5V에서도 일정수준 이상의 인지율을 보여주는 결과를 얻었으며 이 결과는 차량 내에서의 시트를 통한 진동자극의 운전정보 유용성을 보여주는 것으로 사료된다.

• 제어로봇시스템학회논문지
• /
• 제18권3호
• /
• pp.181-187
• /
• 2012

Horse riding is widely recognized as a valuable form of education, exercise and therapy. But, the injuries observed in horse riding range from very minor injuries to fatalities. In order to reduce these injuries, the effective horseback riding simulator is required. In this paper, we proposed the implementation method of horse gait and riding aids for horseback riding robot simulator HRB-1. For implementation of horse gait to robot simulator, we gathered and modified real motion data of horse. We obtained two main frequencies of each gait by frequency analysis, and then simple sinusoidal functions are acquired by genetic algorithm. In addition, we developed riding aids system including hands, leg, and seat aids. With the help of a developed robotic system, beginners can learn the skill of real horse riding without the risk of injury.

• 대한인간공학회지
• /
• 제24권4호
• /
• pp.55-62
• /
• 2005

This study examined the effect of ergonomic heel rest that was designed for drivers who have physical handicap in the low leg muscles or have to drive prolonged hours with frequent foot pedaling. An experiment was designed to test the ergonomic heel rest with traditional foot pedal. Forty subjects participated in the experiment. Electromyography(EMG) was used to monitor the muscle activity and fatigue of right leg, and Electro-goniometer was used to measure the ranges of motions of the knee and ankle. A simulator of driver's seat was built for the experiment and the heel rest was installed on it. In order to examine the low muscle activity and range of motion, subjects used the foot pedal for 15 minutes repetitively for each experimental condition. Another 15 minutes test without the heel rest was also performed for comparison. The Root Mean Square(RMS) and Mean Power Frequency(MPF) Shift were used to quantify the level of muscle activity and local muscle fatigue. In results, statistically significant decreases of muscle activity and fatigue were found in all the low leg muscles. The range of motion of the knee and ankle joint also decreased when the heel rest was used. The mechanism of the heel rest effect was discussed in this study. This type of heel rest can be applied to real driving situation after ensuring the safety, or overcoming the psychological discomfort possibly due to unfamiliarity.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.297-302
• /
• 2007

Vibrating test of vehicle component can be possible in lab-based simulators instead of field testing owing to the development of technology in control algorithm as well as computational process. Currently, Multi-Axial Simulation Table(MAST) is recommended as a vibrating equipment, which excites a target component for 3-directional translation and rotation motion simultaneously and hence, vibrational condition can be fully approximated to that of real road test. But, the vibration-free performance of target component is not guaranteed with MAST system, which is only simulator subjective to the operator. Rather, the reliability of multi-axial vibration test is dependent on the quality of input profile which should cover the required severity of vibrating condition on target component. In this paper, multi-axial vibration testing methodology of vehicle component is presented here, from data acquisition of vehicle accelerations to the obtaining the input profile of MAST using severe data at proving ground. To compare the severity of vibration condition, between real road test and proving ground one, energy principle of equivalent damage is proposed to calculate energy matrices of acceleration data and then, it is determined the optimal combination of special events on proving ground which is equivalent to real road test at the aspects of vibration fatigue using sequential searching optimal algorithm. To explain the vibration methodology clearly, seat and door component of vehicle are selected as a example.