Speed Yaw Research Articles

Approach to imitate maneuvering of lunar roving vehicle under lunar gravity using a terrestrial vehicle

A lunar roving vehicle (LRV) is an important and indispensable detection tool that can not only transport astronauts a long distance from the lunar module but also ensures their safety when moving around the lunar surface. Thus, it is very important to train astronauts to drive the LRV on Earth. However, astronauts will experience different properties and driving sensations for the same vehicle owing to the difference in the gravities of Earth and the Moon. Thus, it is hard to train them on Earth using a normal LRV. Therefore, an approach is used to produce a vehicle that has the same steering properties and driving sensations as the LRV on the lunar surface. This approach involves a control algorithm that is developed in this paper using the H∞ control theory. The math calculation and visual simulation results show that a four-wheel steering imitating LRV, which uses an imitating control algorithm, with either a higher stiffness torsion bar spring or lower payload than the LRV has a high imitation accuracy for the yaw speed, slip angle, and lateral acceleration at the driver’s position. Finally, a highly accurate approach for imitating the steering of an LRV on the lunar surface has been realized, which lays the foundation for training astronauts to drive an LRV.

카메라영상에 의한 DGPS-GIS기반 차선변경 지원시스템의 평가 및 신뢰성 검증

This paper proposes a new assessment and reliability validation method of Lane Departure Assistance System based on DGPS-GIS by measuring lanes with camera vision. Assessment of lane departure is performed with yaw speed measurement and determination method for false alarm of ISO 17361 and performance validation is executed after generating departure warning boundary line by considering deviation error of LDAS using DGPS. Distance between the wheel and the lane is obtained through line abstraction using Hough transformation of the lane image with camera vision. Evaluation validation is obtained by comparing this value with the distance obtained with LDAS. The experimental result shows that the error of the extracted distance of the LDAS is within 5 cm. Also it proves performance of LDAS based on DGPS-GIS and assures effectiveness of the proposed validation method for system reliability using camera vision.

Study on the Control System of the Electro-Controlled Steering Damper Based on Magnetorheological Fluid

This paper introduces a kind of electro-controlled steering damper’s structure and working principle which uses the magnetorheological fluid as the working medium. In order to design the controll system of the electro-controlled steering damper, the model of the steering system and the damper based on magnetorheological fluid are established through the dynamic equations, and a PID controller is used. At last, the paper simulates the controll system using a simulation language Modelica on Works, which is a simulation flatform for comp lex physical system modeling and simulation. The results show that the damper can effectively increase the stabilizing speed of the steering system, decrease the over run of the vehicle’s yaw speed, and improve the vehicle’s steering stabilization, especially when the vehicle running in high speed.

1P1-A28 高速道路における横風を考慮した車両の直進安定走行支援

A strong crosswind has a dangerous effect on driver's operation when a vehicle runs at high speed on an expressway. Therefore, it is necessary to support a driver's operation to reduce a crosswind effect for driving safety. This paper describes a simulation model for stable driving support of a 4WAS (4 wheel active steering) vehicle considering a crosswind effect. A vehicle model was built and a simulation model to control steering angle of each wheel for reducing a crosswind effect was designed. In the simulation model, steering angles of front and rear wheels are calculated to control cornering forces to minimize a lateral acceleration and yaw speed. Simulation results using proposed model are presented.

Potential of electric wheel motors as new chassis actuators for vehicle manoeuvring

The stability and yaw control systems in today's vehicles are increasingly appreciated for active safety. They use individual wheel braking to obtain an extra yaw moment. Adding individual traction, e.g. through electric wheel motors, would increase the available extra yaw moment. The present work investigates the manoeuvrability potential of such a concept. A passenger car employing electric wheel motors at the rear axle is compared with the same vehicle using only brake intervention. The potential, or ultimate limits, are investigated for two driving situations. The time delay in yaw speed change when entering a curve is estimated. A reduction of some 10-30 per cent is found, the highest gains being at low longitudinal speed. For pure lateral translation, the maximum initial lateral acceleration is estimated and a 40 per cent increase is predicted. The investigation is based on mathematical analysis employing a modified version of the common bicycle model. The feasibility of introducing these solutions in series-produced vehicles is discussed briefly. Cost aspects are not considered in any great detail, but it is emphasized that such aspects must be weighed not only against improved manoeuvrability but also against reduced environmental impact and improved longitudinal driveability, all of which are attainable with electric propulsion.

A New Dynamic Multi-D.O.F. Tire-Model

A new dynamic model of the generation of shear forces by pneumatic tires for all speed is proposed. This model is suitable for a wide range of applications from the study of steering performance of vehicle at low speed to realism enhancement for interactive vehicle simulator. The elastic deformation of the belt with respect to the rim is takeninto account, along with the elasto-plastic behavior of rubber-road contact in the contact patch. The model reproduce tire behaviors like frictional vertical torque at standstill, lateral force and vertical torque due to yaw speed, and also relaxation length behavior. Moreover, as the “Pacejka Magic Formula”, it represents very well the standard stationary friction curves.

An Investigation of High-Speed Automobile Steering Response

SUMMARY The significance of the effects of steering compliance and aerodynamic life on high speed automobile's steering response was investigated on two vehicles, a Ford Falcon XW (1969) station-wagon and a GM-Holden Kingswood HQ (1974) sedan. An aerofoil was mounted above the front bumper bar of the Ford Falcon to enable the simulation of vehicles with very degraded aerodynamic characteristics. Mathematical analysis showed the importance of the inclusion of steering compliance effects in determining stability factor, and hence the vehicle's high speed yaw rate sensitivity. Both experiments and theory showed that the actual high speed yaw rate response is not significantly less than that predicted from a low speed skid pad test, however, slight errors were found which are likely to be due to steering system nonlinearity and the effects of aerodynamic lift.