압전 밸브용 압력 레귤레이터

윤소남,김찬용,서우석,박중호,함영복 사단법인 유공압건설기계학회 2006 드라이브·컨트롤 Vol.3 No.2

The pressure regulator which is used for controlling the reducing pressure in the piezoelectrically driven pneumatic valve has been studied. The pneumatic valve of this study object is 2-stage type and consists of a piezoelectric actuator, a controller, a poppet valve and a pressure regulator. Nominal flow of 50 1pm, maximum operating pressure of 0.9MPa and frequency characteristic of 10Hz and over are required in this pneumatic valve, but the pressure regulator is needed because piezoelectric actuator has no ability to control the pressure of 0.9MPa directly. In this study, bimorph type PZT actuator of 25.2 mm(L)x7.2 mm(W)x0.5 mm(H) with constant of -220x10-12 CN-1 was proposed and investigated. Maximum operating force of 0.052 N and maximum displacement of 63 ㎛ were gotten from the fabricated PZT actuator. From the analysis results, the orifice diameter or 0.6mm for a piezoelectric actuator was derived and then the pressure regulator which can be operated under 0.15 MPa easily was designed and manufactured. Performance and effects of design parameters were simulated by the Simulink of Matlab software, and it was confirmed that the performance characteristics of manufactured pressure regulator are superior in the common use pressure of 0.5 MPa to 0.7MPa, The results show that the proposed pressure regulator is suitable for the pneumatic valve with a PZT actuator.

제조 로봇용 서보모터의 양산성능 평가 연구

류경하,이태현,박종원,권혁성,강보식 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.4

The performance and reliability of foreign servomotors and domestic servomotors for manufacturing robots were compared and verified. The mass productivity was confirmed by satisfying the requirements of the demanding companies. The servomotor was designed in consideration of mass productivity while satisfying the requirements of the demanding company. It was mounted on a real robot to check its performance and reliability. To secure mass-production performance, we designed and manufactured easy-to-manufacture parts and jigs to manufacture servomotors and achieved the goal of the mass-production evaluation of servomotors through individual performance evaluation, robot mounting test evaluation, and supplementation.

에어-드롭 해머와 카운터블로 해머 프레스 단조공정의 기계진동 비교해석

김수태,최영휴,주경진 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.4

Air-drop hammer press and counterblow hammer press are widely used power-drop forging hammersemploying different forging blow mechanisms. It is important and necessary to analyze mechanical vibrations of these two different hammers in their forging processes in order to develop high performance forging hammers. In this study, these two forging hammers were mathematically modelled as mass-spring-damper systems. For these two different types of forging hammers, the forging efficiency and mechanical vibrations due to hammer forging blow were theoretically analyzed and compared. The force transmitted to the ground was also determined and compared. Especially, effects of mass ratio and restitution coefficient on forging efficiency were investigated.

농작업 부하데이터를 활용한 44 kW급 전기구동 트랙터의 E-driving 시스템 설계 검증

백승윤,백승민,전현호,이준호,김완수,김용주 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.4

The aim of this study was to verify an E-driving system of a 44 kW-class electric tractor using agricultural workload data. Workload data were acquired during field test (plow tillage, rotary tillage, loader operation, field driving, asphalt driving) using a conventional tractor with a load measurement system. These workload data were converted to data of a 44 kW-class tractor based on the load factor of the engine. These data were used to verify the design of the E-driving system of an electric tractor. High-load operations such as plow tillage, rotary tillage, and loader operation could be performed at stage L and stage M. High-speed operation (asphalt driving) could be effectively performed at stage H using a rated rotational speed of the motor. As a result, the E-driving system of the electric tractor was possible to perform all major agricultural operations according to gear stages of range shift. Based on results of this research, we plan to develop an electric tractor equipped with an E-driving system and conduct research on actual vehicle verification in the future.

지게차 마스트 작동내구를 위한 실차 기반 무인시험장치 개발

조재홍,나선준,김민석,박명관 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.4

In this paper, we develops an unmanned test system for the purpose of realizing an actual forklift-based test-bed for the operation durability of the forklift mast. First, two robot actuators were applied to the lever to replace lever manipulation of the operator. For detecting the height of the fork and the tilt angle of the mast, the laser displacement sensor and the inclinometer were installed to the forklift. Next, the embedded control system was used to control the robot actuator with reference to test mode. Experimental evaluation verified that developed test system was effective and practical for the viewpoint of the repeatability of the test mode.

가상 환경에서의 강화학습 기반 긴급 회피 조향 제어

이훈기,김태윤,김효빈,황성호 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.4

Recently, various studies have been conducted to apply deep learning and AI to various fields of autonomous driving, such as recognition, sensor processing, decision-making, and control. This paper proposes a controller applicable to path following, static obstacle avoidance, and pedestrian avoidance situations by utilizing reinforcement learning in autonomous vehicles. For repetitive driving simulation, a reinforcement learning environment was constructed using virtual environments. After learning path following scenarios, we compared control performance with Pure-Pursuit controllers and Stanley controllers, which are widely used due to their good performance and simplicity. Based on the test case of the KNCAP test and assessment protocol, autonomous emergency steering scenarios and autonomous emergency braking scenarios were created and used for learning. Experimental results from zero collisions demonstrated that the reinforcement learning controller was successful in the stationary obstacle avoidance scenario and pedestrian collision scenario under a given condition.

승용형 농기계용 직진 자동조향장치 주행특성 연구

원진호,전진택,홍영기,양창주,김경철,권경도,김국환 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.4

This paper introduces an automatic steering system for straight traveling capable of being mounted on drivable agricultural machinery which user can handle it such as a tractor, a transplant, etc. The modular automatic steering device proposed in the paper is composed of RTK GNSS, IMU, HMI, hydraulic valve, and wheel sensor. The path generation method of the automatic steering system is obtained from two location information(latitude and longitude on each point) measured by GNSS in advance. From HMI, a straight path(AB line) can be created by connecting latitude and longitude on each point and the device makes the machine able to follow the path. During traveling along the reference path, it acquires the real time position data every sample time(0.1s), compares the reference with them and calculates the lateral deviation. The values of deviation are used to control the steering angle of the machine using hydraulic valve mounted on the axle of front wheel. In this paper, Pure Pursuit algorithm is applied used in autonomous vehicles frequently. For the analysis of traveling characteristics, field tests were executed about these conditions: velocity of 2, 3, 4km/h which is applied to general agricultural work and ground surface of solid(asphalt) and weak condition(soil) such as farmland. In the case of weak ground state, two experiments were executed about no-load(without work) and load(with work such as plowing). The maximum average deviations were presented 2.44cm, 7.32cm, and 11.34cm during traveling on three ground conditions : asphalt, soil without load and with load(plowing).

2속 변속 감속기의 구조 안전성 분석과 위험속도 해석

강진경,유영락,박규태 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.4

The structure and operating principle of the 2-speed shift reducer were explained, the allowable bending stress value of the material was compared with the analysis result through FM structural analysis program, and the average stress distribution value of von Mises was performed on the gear root atmosphere. The structural safety of the 2-speed planetary gear reducer was verified through FM structural analysis. The natural frequency was calculated by applying the specifications of the planetary gears of the 2-speed gearbox, and the critical speed of resonance was calculated by calculating the natural frequency and the transmission error of the engaged gear pair. As a result of analyzing the critical speed, since it is formed higher than the actual operating speed range, it is considered safe because there is no resonance problem due to the suggested specifications of the planetary gears of the 2-speed shift reduction.

전지형 크레인의 인양물 충돌방지를 위한 환경탐지 센서 시스템 개발

김지철,김영재,김민극,이한민 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.4

Construction machinery is exposed to accidents such as collisions, narrowness, and overturns during operation. In particular, mobile crane is operated only with the driver's vision and limited information of the assistant worker. Thus, there is a high risk of an accident. Recently, some collision avoidance device using sensors such as cameras and LiDAR have been applied. However, they are still insufficient to prevent collisions in the omnidirectional 3D space. In this study, a rotating LiDAR device was developed and applied to a 250-ton crane to obtain a full-space point cloud. An algorithm that could provide distance information and safety status to the driver was developed. Also, deep-learning segmentation algorithm was used to classify human-worker. The developed device could recognize obstacles within 100m of a 360-degree range. In the experiment, a safety distance was calculated with an error of 10.3cm at 30m to give the operator an accurate distance and collision alarm.

콘 크러셔의 전달 하중 및 기여도 분석

김대지,정진태,이창선,송창헌 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.4

The aims of this study was to estimate transfer force delivered to cone crusher housing and contribution of force transmission. The rock crushing condition caused vibrations in the cone crusher housing, which were experimentally measured, and frequency response functions (FRF) were also found through modal impact tests. Vibration data and frequency response functions were applied to the transfer path analysis (TPA) model. Next, transfer forces delivered to the cone crusher housing were quantified via the TPA method. Contribution of force transfer was also analyzed based on force estimation results. Finally, this study describes basic concepts and components of the TPA method and reviews its applicability to rotating machinery that experiences impact vibrations and forces.