• Journal of Auto-vehicle Safety Association
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• v.14 no.1
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• pp.39-44
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• 2022

This paper presents a development of throttle and brake controller for autonomous vehicle simulation environment. Most of 3D simulator control autonomous vehicle by throttle and brake command. Therefore additional longitudinal controller is required to calculate pedal input from desired acceleration. The controller consists of two parts, feedback controller and feedforward controller. The feedback controller is designed to compensate error between the actual acceleration and desired acceleration calculated from autonomous driving algorithm. The feedforward controller is designed for fast response and the output is determined by the actual vehicle speed and desired acceleration. To verify the performance of the controller, simulations were conducted for various scenarios, and it was confirmed that the controller can successfully follow the target acceleration.

• IEMEK Journal of Embedded Systems and Applications
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• v.15 no.5
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• pp.215-225
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• 2020

Light detection and ranging (LiDAR) sensors detect the distance of the surrounding environment and objects. Conventional LiDAR sensors require a certain amount of a power because they detect objects by transmitting lasers at a regular interval depending on a constant resolution. The constant power consumption from operating multiple LiDAR sensors is detrimental to autonomous and electric vehicles using battery power. In this paper, we propose two algorithms that improve the inefficient power consumption during the constant operation of LiDAR sensors. LiDAR sensors with algorithms efficiently reduce the power consumption in two ways: (a) controlling the resolution to vary the laser transmission period (T_P) of a laser diode (LD) depending on the vehicle's speed and (b) reducing the static power consumption using a sleep mode depending on the surrounding environment. A proposed LiDAR sensor with a resolution control algorithm reduces the power consumption of the LD by 6.92% to 32.43% depending on the vehicle's speed, compared to the maximum number of laser transmissions (N_x·max). The sleep mode with a surrounding environment-sensing algorithm reduces the power consumption by 61.09%. The proposed LiDAR sensor has a risk factor for 4-cycles that does not detect objects in the sleep mode, but we consider it to be negligible because it immediately switches to an active mode when a change in surrounding conditions occurs. The proposed LiDAR sensor was tested on a commercial processor chip with the algorithm controlling the resolution according to the vehicle's speed and the surrounding environment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.5
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• pp.437-446
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• 2021

As flying vehicle's speed is getting faster, the magnitude of aerodynamic heating is getting bigger. High-speed vehicle's exterior skin is heated to hundreds of degrees, and electrical equipments inside the vehicle are heated, simultaneously. Since allowable temperature of electrical equipments is low, they are vulnerable to effect of aerodynamic heating. These days, lots of techniques are applied to estimate temperature of electrical equipments in flight condition, and to make them thermally safe from heating during flight. In this paper, new model building technique for thermal safety analysis is introduced. To understand internal thermal transient characteristic of electrical equipment, simple heating experiment was held. From the result of experiment, we used our new building technique to build thermal analysis model which reflects thermal transient characteristic of original equipment. This model can provide internal temperature differences of electrical equipment and temperature change of specific unit which is thermally most vulnerable part in the equipment. So, engineers are provided much more detailed thermal analysis data for thermal safety of electrical equipment through this technique.

• Smart Structures and Systems
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• v.29 no.5
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• pp.661-675
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• 2022

In this paper, an electric vehicle drives with efficient control and low cost hardware using four quadrant DC converter with Permanent Magnet Direct Current (PMDC) motor fed by DC boost converter is presented. The main idea of this work is to improve the energy efficiency of the conversion chain of an electric vehicle by inserting a boost converter between the battery and the four quadrant-DC motor chopper assembly. Consequently, this method makes it possible to maintain the amplification gain of the 4 quadrant chopper constant regardless of the battery voltage drop and even in the presence of a fault in the battery. One of the most important control problems is control under heavy uncertainty conditions. The higher order sliding mode control technique is introduced for the adjustment of DC bus voltage and mechanical motor speed. To implement the proposed approach in the automotive field, experimental tests were carried out. The performances obtained show the usefulness of this system for a better energy management of an electric vehicle and an ideal control under different operating conditions and constraints, mostly at nominal operation, in the presence of a load torque, when reversing the direction of rotation of the motor speed and even in case of battery chamber failure. The whole system has been tested experimentally and its performance has been analyzed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.6
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• pp.1125-1132
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• 2012

The researches on driver assistance systems that can prevent an accident have been actively performed due to social issues of traffic accidents with development of vehicle industry in recent. It is required for researchers to develope systems which assist driver's perception and judgment when considering that over 70% of traffic accidents occur by drivers' carelessness and 75% of the total accidents occur at the speed of less 29km per hour. In this paper, we implemented a front and rear vehicle monitoring system that monitors distance from a vehicle to obstacles in real-time at the low-speed or back-ward driving. The proposed system consists of ultrasonic sensors of high angle and wide angle of beam spread, ATmega128, and DSP processor.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.440-445
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• 2002

In this paper, traction system for urban transit maglev system is proposed. Using vector control strategy to control magnitude and frequency of output voltage transiently is general. But in case of traction system for railway vehicle, it is impossible that adapt vector control because there is one-pulse mode in a high speed region. So this paper proposes the control strategy using vector control in a low speed region and slip frequency control in a high speed region. And also proposes overmodulation method that makes to change in one-pulse mode softly. The performance of traction system will be verified by simulation results using ACSL.

• Journal of Auto-vehicle Safety Association
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• v.9 no.3
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• pp.7-12
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• 2017

The whiplash is the most important issue of low speed rear-impact. So auto makers are committed to developing a seat to improve whiplash injury. Most NCAP tests have been used by same pulse (Mid Velocity 16kph). Only Euro NCAP uses different pulse that consists of Low, Mid, High velocity. But Euro NCAP also uses same pulse in Mid velocity as other NCAP test. That Mid velocity NCAP pulse was made by rear impact that has 90's vehicle structure properties. That pulse was used until now days. However these days, auto maker use more high tensile steel than 90's as customer and society demand more fuel efficiency and light vehicle with good safety structure. So modern vehicles have different pulse patterns of rear impact than NCAP pulse and 90's vehicle crash properties. In this paper, the test was conducted by following condition. Target car was impacted by the rigid barrier with certain velocity. Finally target vehicle gained delta V 16kph which was same velocity as NCAP Mid Velocity pulse. It is critical velocity which occur long period neck injury. It is very different pulse that was gained by real car impact from NCAP pulse. And it has higher peak G with high fluctuation and short duration than NCAP pulse.

• Proceedings of the KSR Conference
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• 2003.10a
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• pp.210-215
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• 2003

Korean High Speed Train (KHST) has been tested on high speed line in JungBu site since it was developed in 2002. The KHST figured 7 cars was modeled for dynamic simulation with Vampire program. and the data acquisition system was used to test successfully the on-line test for proving the dynamic performance of KHST. The comparison between test and simulation results for dynamic behavior of KHST was tried in this paper and it was very difficult because the environmental conditions and running conditions have an effect on the test results and these conditions are unable to be modeled for dynamic analysis. Also the parameters for data acquisition system for test are usually not same to simulation conditions. Therefor, in this paper the acceleration data after filtering with low pass filter below 1Hz were used to compare between test and simulation results because the low frequency range is useful to evaluate the dynamic performance for railway vehicle system, so as steady state curving acceleration. The results show that both are similar in low frequency range.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.403-404
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• 2017

In an electric vehicle driving system, the regeneration power charging the battery with electricity is applied as the driver controls the brake. This paper is proposed a torque compensation algorithm that can regenerate due to extend regeneration area at the low speed of EV system. In order to verify the proposed method, PSIM simulation is performed and it is confirmed that regeneration occurred the proposed method is regenerated at low speed by comparing the existing method with the proposed method.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.5
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• pp.79-83
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• 2006

The present low speed crash regulations and RCAR test for insurance estimate do not tend to reflect car crash occurred on a road. Therefore, car makers are trying to readjust test standard be similar to a real situation. Passenger cars and SUV vehicles on the market will be subject to this study for car to car crash. In addition, we will discuss improvement of test methods for a low speed crash and direction of bumper design by performing this impact analysis.