Investigation on the rudder force of a ship in large drifting conditions with the MMG model

Journal of Marine Science and Technology - The rudder force, including interference with a ship hull in large drifting conditions, is investigated in this study by captive model tests using a ship...     

Analysis of a large injection-molded body using knowledge-based flow process technology

A knowledge-based flow process is presented for large injection-molded body technology (LIMBT). Injection molding of a large body is a difficult technique because of the many factors and their interactions during the molding process. The proposed flow process can support LIMBT through integration of CAE(Computer-Aided Engineering), CAI (Computer-Aided Inspection), and monitoring systems. CAE and DOE (Design of Experiment) are used to construct an optimal mold design in terms of gates and runners and to identify working conditions for the molding process. CAI and monitoring systems with temperature sensors and pressure sensors can be used to inspect the physical molding process and the molded parts. The flow process of a large body is systematically planned and constructed using a knowledge-based flow process with DOE and computer-aided technologies. The proposed flow process is implemented for the molding process of an automobile front bumper fascia.     

Lateral controller design for an unmanned vehicle via Kalman filtering

This paper proposes a lateral control system for an unmanned vehicle that is designed to improve the responsiveness of the system with the use of a PD control. The vehicle heading error can be stabilized, and the transient response characteristics can be improved using the proposed controller. A mathematical model of the vehicle dynamics using two degrees of freedom was developed for the controller design. The waypoint tracking method for autonomous navigation was tested with incorporation of the Point-to-Point algorithm with position and heading measurements received from GPS receivers via Kalman filtering. The performance of the designed controller was verified through experiments with a real vehicle.     

Effects of ground vehicle inclination on underhood compartment cooling

This work reports on experiments carried out on a real passenger vehicle in a large wind tunnel to investigate the effects of car inclination on underhood cooling. The vehicle??s underhood is instrumented by thermocouples that measure the temperatures of many underhood components during different car functioning modes. Measurements are carried out for three thermal functioning points at car speeds 90, 110 and 130 km/h. In these experiments the engine was in operation and the front wheels positioned on the test facility with power-absorption-controlled rollers. Three car inclinations are investigated: flat, uphill and downhill. The results show that car inclination, even if very small, can have significant effects on underhood cooling and must be taken into consideration in numerical simulations and controlled in experimental tests. It was shown that down-hill and up-hill inclinations increase temperatures of components, air zones and engine parameters in the underhood, with higher effect for the down-hill inclination. Temperature increases in constant-speed driving phase are higher than in thermal soak phase.     

Simulation of the vertical bending fatigue test of a five-link rear axle housing

This study seeks a practical method for simulating the vertical bending fatigue test of the BANJO housing of a five-link rear axle. Linear static and transient dynamic finite element models are constructed for the rear axle in which the rubber bushings and the bearings of the axle shafts are reasonably modeled with solid and shell elements, respectively, for simplicity. The calculated results are compared with the measured strain histories, and the results indicate that the finite element models constructed are reasonable. The hypothesis of equal fatigue damage is applied to determine the Hainan proving ground driving life prediction that is equivalent to the constant amplitude fatigue life in the vertical bending fatigue test.     

Validation of the 6-dof vehicle dynamics model and its related VBA program under the constant radius turn manoeuvre

For a 6-dof (degrees of freedom) nonlinear vehicle dynamics model and its related VBA (Visual Basic for Applications) program, which were recently derived and coded by the authors, validations are carried out under the constant radius turn manoeuvre. This model has the uniqueness that the longitudinal translation, lateral translation and yaw rotation of a platform are described by an inertial ground coordinate system and the body-roll, body-pitch, and body-yaw rotations by a platform-fixed coordinate system. The simplified STI tire model is applied for the calculation of combined longitudinal and lateral tire forces. Vehicles used in the calculation are a NISSAN DATSUN 210 (manufactured in 1980) and a HONDA ACCORD (1984). The calculation results of the present 6-dof model are compared with the published test data and those of a simpler 3-dof lateral dynamic equation based on another coordinate system. As a result of the comparison, the present 6-dof results agree very well with those of the 3-dof model and give a partial consistency with the test data.     

Current sensorless drive method for electric power steering

This paper proposes a current sensorless drive method by using the mathematical modeling of a surface-mounted permanent magnet synchronous motor (SPMSM) and a dead-time compensation method to reduce the calculated current error caused by differences between real output voltages and voltage commands. The proposed method is implemented by using only a processor algorithm internally, i.e., without any voltage-sensing circuit hardware, such as filtering circuits and current sensor feedback circuits. To show the effectiveness of the proposed method, MATLAB simulations are carried out with an Electric Power Steering (EPS) System containing an SPMSM, a motor drive system and a mechanical gear system. The result shows the validity of the proposed method.     

Robust yaw stability control for electric vehicles based on active front steering control through a steer-by-wire system

A robust yaw stability control design based on active front steering control is proposed for in-wheel-motored electric vehicles with a Steer-by-Wire (SbW) system. The proposed control system consists of an inner-loop controller (referred to in this paper as the steering angle-disturbance observer (SA-DOB), which rejects an input steering disturbance by feeding a compensation steering angle) and an outer-loop tracking controller (i.e., a PI-type tracking controller) to achieve control performance and stability. Because the model uncertainties, which include unmodeled high frequency dynamics and parameter variations, occur in a wide range of driving situations, a robust control design method is applied to the control system to simultaneously guarantee robust stability and robust performance of the control system. The proposed control algorithm was implemented in a CaSim model, which was designed to describe actual in-wheel-motored electric vehicles. The control performances of the proposed yaw stability control system are verified through computer simulations and experimental results using an experimental electric vehicle.     

Travel differences by gender for older people in London

As a guarantee of life quality, older people’s travel demand has to be satisfied, so understanding their travel demand is important. An important point to bear in mind is that older people are not a homogeneous group but that distinguishing between older women and older men in their mobility needs and travel patterns is necessary. Older people’s travel demand needs to be investigated from many different aspects, including trip generation, travel time, and mode choice. In this study, the investigation is focused on older people’s trip chaining, including trip chain complexity, tour composition in a chain.     

A method for extracting key performance indicators from maritime safety management norms

The maritime transportation industry currently employs several mandatory and non-mandatory norms of organizational safety management. These safety norms are commonly included in integrated maritime safety management systems, which aim at developing, monitoring, controlling and improving the safety of all related shipping operations. These systems are typically evaluated by following key performance indicators, which enable defined measures for various safety management components. However, the identification of indicators addressing safety management requirements constitutes a complex and generally unsystematic process for safety managers in the maritime industry. This article proposes a new method to assess the guidelines available in maritime safety management norms. The proposed method is applied to assess the content of two maritime safety management norms. The aim of this assessment is to identify a set of maritime safety management indicators that can systematically measure the most relevant components of maritime safety management. The application of this method resulted in the identification of 53 key performance indicators for monitoring and reviewing 23 identified safety management components that are commonly integrated into the functioning of maritime safety management systems. The method proposed provides guidance to accurately capture the actual aim and function of the key performance indicators. Furthermore, the indicators and safety components obtained with this method can be adopted as the basis for a safety management system and/or for the analysis of a safety management system already established in the industry.