• 제어로봇시스템학회논문지
• /
• 제14권10호
• /
• pp.1022-1028
• /
• 2008

This article presents an omni-tread snake robot that designed to locomote on narrow space and rough terrain. The omni-tread snake robot comprises three segment, which are linked to each other by 2 degrees of freedom joints for the pitch and yaw motion. Moving tracks on all four sides of each segment guarantee propulsion even when the robot rolls over. The 2 DOF joint are actuated by 2 servo motors which produce sufficient torque to lift the one leading or trailing segments up and overcome obstacles. This paper applies articulated steering technique to get omni-tread snake robot's kinematics model.

• 로봇학회논문지
• /
• 제9권4호
• /
• pp.250-257
• /
• 2014

In this paper, a new mobile robot, so called a rollerbot, is presented, which has single body and rugby-ball shaped roller wheel. A rollerbot has single point contact on ground and low energy consumption in motion because of the reduced friction. By changing center of mass using a balancing weight, a rollerbot is able to get steering force. The vertical position of mass center of the rollerbot in this paper is designed to lie inside radius of the roller wheel, so that to have stable equilibrium position. Thus, the posture and the steering control of the rollerbot can be easily done by changing the center of mass. Kinematics of the rollerbot is derived by transformation of differential motion in this paper.

• 한국안전학회지
• /
• 제14권4호
• /
• pp.85-92
• /
• 1999

Vehicle rollover is an important issue for the traffic safety. Rollover can occur from the driver's action, the vehicle characteristics, or the road condition. This study is about the rollover propensity analysis of a jeep vehicle using the steering and braking maneuver, which is the combined result by the driver and the vehicle. Simple equations of roll motion is used to analyze the roll motion and a special purpose vehicle dynamics program is used to simulate the rollover of the jeep vehicle. From the simulation, an incipient rollover motion of the vehicle was found. However, the more complete rollover propensity analysis would require further investigation using roll dynamic sensitivity study.

• 대한기계학회논문집A
• /
• 제23권6호
• /
• pp.931-942
• /
• 1999

This paper develops a 3 DOF vehicle model which includes lateral, roll and yaw motion to study a 4WS vehicle. The model is used for the simulation of a 4WS vehicle behavior, and to derive a control algorithm for rear wheel steering. This paper uses a feedforward plus feedback control scheme to compute a rear wheel steering angle. The feedforward control scheme for computing the first rear wheel steering angle uses a gain which is acquired by multiplying a proper value on a gain to maintain a zero sideslip angle. The feedback control scheme for computing the second rear wheel steering angle uses fuzzy logic and model following control scheme. A linear 2 DOF model is used as a reference model for model following control, and is derived from the developed 3 DOF model by neglecting sprung mass roll motion. A reference state variable is yaw rate, and is computed using the linear 2 DOF model. J-turn and lane change maneuver simulation are performed to show the effectiveness of the developed control scheme. The simulation results show that the 4WS vehicle with the developed control scheme has much better performance in yaw rate, lateral acceleration, roll angle, and sideslip angle than the 2WS vehicle. Also, the results show that the performance of the developed control is close to the one of an optimal control which assumes all states are perfect.

• 한국해양공학회지
• /
• 제19권2호
• /
• pp.67-73
• /
• 2005

This paper describes depth, heading and speed control of an underwater vehicle that has four stern thrusters of which forces are coupled in the diving and, steering motion, as well as the speed of the vehicle. The optimal linear quadratic controller is designed based on a linearized- state space model, developed by combining the dynamic equations of speed, steering and diving motion. The designed controller gives provides an optimal thrust distribution, minimizing the given performance index to control speed, depth and heading simultaneously. To validate the performance of the controller, a simulation and tank-test are carried out with DUSAUV (Dual Use Semi-Autonomous Underwater Vehicle), developed by KORDI as a test-bed for testing new underwater technologies. Optimal gains of the controller are tuned, using a computer simulation environment with a nonlinear 6-DOF numerical DUSAUV model, developed by PMM (Planner Motion Mechanism) test. To verify the performance of the presented controller in experiment, a tank-test with DUSAUV is carried out in the ocean engineering basin in KORDI. The experimental results are also compared with the simulation results to investigate the accordance of the numerical and the real mode.

• 한국산학기술학회논문지
• /
• 제16권7호
• /
• pp.4842-4848
• /
• 2015

본 논문은 재구성 빔 스티어링 안테나와 전방향성(루프) 안테나 간 정지상태와 이동상태일 때 통신 성능 비교를 보여준다. 두 안테나는 동일한 직물(${\varepsilon}_r=1.35$, $tqn{\delta}=0.02$) 위에 제작되었으며 5 GHz 대역에서 동작한다. 재구성 안테나는 빔 방향을 조향할 수 있도록 설계되었다. 빔 스티어링 기능을 수행하기 위해 안테나는 두 개의 핀 다이오드를 사용한다. 측정된 최대 이득은 5.9-6.6 dBi 이고 반 전력 빔 폭(HPBW)는 $102^{\circ}$ 이다. 통신효율을 비교하기 위해 GNU Radio Companion 소프트웨어툴과 USRP(User Software Radio Peripheral) 장비를 이용하여 두 안테나의 BER(Bit Error Rate)과 SNR(Signal-to-Noise Ratio)를 측정하였다. 그리고 송, 수신 안테나 사이의 일정한 거리에서 수신 안테나가 고정된 상태와 이동중인 상태 두 가지 경우를 비교하였다. 본 측정은 이상적인 전파환경인 무손실 안테나 챔버와 전파간섭이 존재하는 실제적인 환경인 스마트홈에서 진행되었다. 본 측정의 결과로 빔 스티어링 안테나의 성능이 루프 안테나보다 우수함을 알 수 있다. 또한, 통신효율을 비교하면 측정환경 측면에서는 무손실 안테나 챔버가 스마트홈보다 우수하며, 안테나의 고정/이동 측면에서는 고정된 상태가 이동중인 상태보다 좋은 결과를 보임을 알 수 있다.

• Journal of Advanced Research in Ocean Engineering
• /
• 제1권2호
• /
• pp.134-147
• /
• 2015

This study proposes a method to determine the effective angular velocity of each motor of a specific four-rows tracked vehicle (FRTV) in order to follow a given turning radius. The configuration of the four-rows tracked vehicle is introduced, and its dynamics analysis model is built using the DAFUL commercial software. The soil has been assumed to be hard ground, and the friction force between the ground and the tracked links is calculated using the Coulomb friction model. This paper uses a simulation to show that the error in the position increased with respect to the angle of the curvatures, so a method is proposed to compensate for the error in the motion of the motors. Various simulations are then carried out to verify the proposed formulation. The effects of the soil characteristics and the driving velocity will be further investigated in future studies.

• Journal of Advanced Marine Engineering and Technology
• /
• 제33권2호
• /
• pp.288-294
• /
• 2009

The purpose of this study is manufacturing of monolithic housing for modularization of steering gear. Monolithic housing is difficult to weld with only rotation and linear motion. It is for this reason that housing of joining parts have a slope of 76.3 degrees. For this reason, welding trajectory was measured by the cooperative controled robot system, and then allowing for measured results, we developed the dedicated system. The developed system can be welded by using only 3 axises in contrast with robot system using 8 axises in housing welding. In addition, we applied CMT and laser welding device to dedicated system and as a result of experiment, sound bead and excellent roundness could be obtained.

• 대한기계학회논문집A
• /
• 제25권1호
• /
• pp.32-38
• /
• 2001

This paper presents an approximate synthesis of 5-SS multi link suspension for 2 D.O.F motions. In the proposed synthesis method, alteration curves of camber, toe, kingpin and caster angles are optimized during the bump rebound and the steering motions. And joint positions can be located within desired boundari es. Especially, steering motions are considered for control of kingpin offset and caster trail. Prescribed motions contain both wheel center positions and imaginary kingpin axes in the multi link type suspension. Constraint equations are formulated with di splacement matrix and velocity matrix using instantaneous screw axis.

• 한국생산제조학회지
• /
• 제8권1호
• /
• pp.150-157
• /
• 1999

In this study, the loader was completed that has 4-wheel gear driven drivetrain of study (Ⅰ), the 4-wheel steering with power wheel type, all-wheel traction system, and joy-stick type lever for hydraulic control valve. From driving test of the developed 4WD and 4WS type loader, we obtained that the minimum circling radius and the necessary width in circling motion reduced about 40% and 33% compared with 2WS type loader. Also, all-wheel traction system could keep the tires glued to the ground with greater stability, the power steering allowed a smoother operation, and the joy-stick type lever offered easily to control. Thus, the developed loader having these functions was very fit in a small cattle shed or rugged ground.