• International Journal of Automotive Technology
• /
• v.7 no.2
• /
• pp.187-193
• /
• 2006

When emergency evasion during running is required, a driver sometimes causes a vehicle to drift, that is, a condition in which the rear wheels skid due to rapid steering. Under such conditions, the vehicle enters a very unstable state and often becomes uncontrollable. An unstable state of the vehicle induced by rapid steering was simulated and the effect of differential steering assistance was examined. Results indicate that, in emergency evasion while cornering and during which the vehicle begins to drift, unstable behavior like spins can be avoided by differential steering assistance and both the stability and control of the vehicle is improved remarkably. In addition, reduction of overshoot during spin evasion by the differential steering assistance has been shown to enable the vehicle to return to a state of stability in a short time in emergency evasion during straight-line running. Moreover, the effectiveness of differential steering assistance during emergency evasion was confirmed using a driving simulator.

• Journal of Biosystems Engineering
• /
• v.34 no.5
• /
• pp.331-341
• /
• 2009

A double-end rod hydraulic cylinder is widely used with a steering valve for the steering control system in large tractors. For the development of automatic steering controller, the feasibility of using a proportional control valve replacing the conventional manual steering valve to control the position of hydraulic steering cylinder was investigated in terms of the max. overshoot, the steady-state error and the rise time. A simulation model for the electrohydraulic steering system with load using AMESim package was developed to be valid so that the proper control algorithm could be chosen through the computer simulation. It could be concluded that the P-control algorithm was sufficient to control the electrohydraulic steering system, where the control frequency should be no greater than 20 Hz at the P-gain of 5. In particular, the performance of the developed steering controller was satisfactory even at the conditions of varying flow rates and loads.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1874-1879
• /
• 2004

This paper validates new type electric power steering (EPS) system which is driven by a uni-direction rotational motor and two electromagnetic clutches. The assist motor of the new type EPS produces a torque for assisting the steering in only one direction and two electromagnetic clutches transmit the assist torque to the pinion gear in either left or right direction with respect to the steering rotation. In order to evaluate the static and dynamic characteristics of the new type EPS, the EPS has been modeled by using the well known customized software such as MSC.ADAMS and MSC.CarSim. The ADAMS software has been used to investigate the static characteristics of the proposed system. ADAMS, however, can not describe dynamics of a vehicle and perform the simulation under the various road conditions. Thus the dynamic characteristics of the vehicle including the EPS are analyzed very well by using the CarSim software. A sinusoidal steering input command is applied to the propose EPS system in order to evaluate the static characteristics, while the double lane changes are applied to the vehicle with the EPS in order to evaluate the dynamic performance. Through a series of simulations, we can conclude that the propose EPS shows the stable dynamic characteristics when the rotational direction is changed.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.2
• /
• pp.111-119
• /
• 2017

This paper presents a method to determine the rear steering angle in integrated chassis control with electronic stability control (ESC) and rear wheel steering (RWS). A control yaw moment needed to stabilize a vehicle should be distributed into the tire forces generated by the ESC and RWS. Weighted pseudo-inverse control allocation (WPCA) is adopted to determine the tire forces. Four methods are proposed to calculate the rear wheel steering angle. To validate the proposed methods, a simulation is performed using a vehicle simulation software package, CarSim. The simulation results show that the proposed method for determining the rear wheel steering angle improves the performance of the integrated chassis control.

• Journal of the Ergonomics Society of Korea
• /
• v.28 no.2
• /
• pp.9-16
• /
• 2009

The aim of this study was to evaluate the effects of the driving performance and workload according to changing driving environment and types of steering wheel. Twelve drivers who participated in this study consisted of two groups; six Japanese as the left-lane drivers who was accustomed to driving on left-hand side of the road, and six Europeans, Americans, and Korean as the right-lane drivers who was accustomed to driving on right-hand side of the road. They were asked to operate a driving simulator while using two different types of steering wheel (for the left-hand side driving and the right-hand side driving). During the experiment, a range of data were measured including driving performance, mental workload, and eye movements which were recorded in order to identify the amount of time looking towards the in-vehicle route guidance. Results indicated that the use of the steering wheel by parallel moving led to increase high attentional demand and worse glance behavior to traffic signs for the left-lane drivers. In the case of the right-lane drivers, the effects by changing driving direction were more effective than the types of steering wheel due to their habit or traits.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1483-1488
• /
• 2005

As the development of microprocessor technology, electric power steering(EPS) system which uses an electric motor came to use a few years ago. It can solve the problems associated with hydraulic power steering. The motor only operates when steering assistance is needed, so it can save fuel and can reduce weight and cost by eliminating hydraulic pump and piping. As one of performance criteria of EPS systems, the transmissibility from road wheel load to steering wheel torque is considered in this paper. The transmissibility can be studied by fixing the steering wheel and calculating the torque needed to hold the steering wheel from road wheel load. A proportion-plus-derivative control is needed for EPS systems to generate desired static torque boost and avoid transmissibility of fluctuation. A pure proportion control can' satisfy both requirements.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.5
• /
• pp.747-752
• /
• 2011

Recently, skid steering methods have been increasingly applied to unmanned ground vehicles since they can provide a narrow turn that general steering methods like ackerman steering may not provide. However, dynamic behaviors of the skid steering vehicles with articulating arms which occur during a steering are very complicated and coupled. This makes it difficult to control vehicles and in severe case vehicles may loose stability. There are two methods to control unmanned ground vehicles. The first one is speed control method generally used with easiness and robustness in remote vehicle control. The next one is torque control allowing the vehicles to get better performance in several cases provided careful application is achieved. This paper addresses dynamic phenomena of skid steering vehicles during steering and compares with vehicle driving control methods between torque(traction force) control and speed control.

• Korean Journal of Agricultural Science
• /
• v.37 no.1
• /
• pp.123-130
• /
• 2010

A steering control system based on CAN(Controller Area Network) for autonomous tractor was developed to reduce duty of a central processing computer and to improve performance of steering control in terms of reduced control interval and error. The steering control system consisted of a SCU (Steering Control Unit), an EHPS system, and a potentiometer. The SCU consisted of an MCU (Micro Controller unit), an A/D converter, and a DC-DC converter, and a PID controller was used to control steering angle. The steering control system was communicated with the computer by CAN-bus. Each actuator and implement was connected to a multi-function board interfacing with the computer through a USB cable. Without CAN, control interval of the autonomous tractor was 1.5 seconds. When the CAN-based steering control system was combined with the autonomous tractor, however, control interval of the integrated system was reduced to those less than 0.05 seconds. When the autonomous tractor was operated with 1.5-s and 0.05-s control cycles at a 0.63-m/s travelling speed, the trajectories were close to straight lines for both of the control cycles. For a 1.34-m/s traveling speed, tractor trajectory was close to sine wave with a 1.5-s control cycle, but was straight line with a 0.05-s control cycle.

• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.5
• /
• pp.403-409
• /
• 2014

For ground-based telescope application, the performance assessment of tip-tilt actuator is important because the optical quality of telescope depends upon the windshake compensation ability of the fast steering secondary mirror. But it is difficult to measure the performance characteristics of the actuators due to the large size mirror and test facilities including the vacuum support and structural frame. In this paper, the full-scale tip-tilt test bed for the large size secondary mirror with diameter of 1m is built and the several tests are performed including the range, resolution and frequency response function. From the measurement results, it is shown that the tip-tilt actuator can successfully compensate the windshake with frequency of maximum 12 Hz and be a candidate for the Giant Magellan Telescope.

• Aerospace Engineering and Technology
• /
• v.7 no.2
• /
• pp.53-57
• /
• 2008

In this article, we discuss steering laws for control moment gyro cluster, which have been studied on the project, "Development of control moment gyro engineering model for middle-size spacecraft", supported by Ministry of Knowledge Economy, Korea. We compare performance of MP, SR, SR Escape/Avoidance steering laws and check each law's performance by simulations and experiments.