Norhazimi Hamzah

A review of active yaw control system for vehicle handling and stability enhancement

Yaw stability control system plays a significant role in vehicle lateral dynamics in order to improve the vehicle handling and stability performances. However, not many researches have been focused on the transient performances improvement of vehicle yaw rate and sideslip tracking control. This paper reviews the vital elements for control system design of an active yaw stability control system; the vehicle dynamic models, control objectives, active chassis control, and control strategies with the focus on identifying suitable criteria for improved transient performances. Each element is discussed and compared in terms of their underlying theory, strengths, weaknesses, and applicability. Based on this, we conclude that the sliding mode control with nonlinear sliding surface based on composite nonlinear feedback is a potential control strategy for improving the transient performances of yaw rate and sideslip tracking control.

Yaw stability improvement for four-wheel active steering vehicle using sliding mode control

Active steering control is one of the approach that can be used to improve the vehicles lateral and yaw stability. By combining active front steering and active rear steering control, the vehicles handling and stability can be improved via four wheel active steering (4WAS) control. In this paper, a robust control algorithm of sliding mode control is designed for 4WAS vehicle. Single track 2 d.o.f linear model is utilized for controller design and simulation purpose. Simulation for 4WAS and front steering (AFS) is carried out in Simulink for step steer and double lane change maneuver to verify the effectiveness of the proposed control system. The result shows that the 4WAS perform better than the AFS in tracking the desired response trajectory.

Advanced single-phase AC-DC converter using single-phase matrix converter topology

This paper proposes advanced single-phase AC-DC converter using single-phase matrix converter (SPMC) topology incorporating with active power filter function. The topology is also capable of incorporating many other features for controlled rectifier operation that includes; bidirectional, regenerative and dual converter capabilities. The PWM technique was used to calculate the switch duty ratio to synthesize the output. Switch commutation arrangements were developed that allows dead time to avoid current spikes of non-ideal switches whilst providing a current path for the inductive load to avoid voltage spikes. Selected simulation and experimental results are presented to verify proposed operation.

Computer simulation of single-phase control rectifier using single-phase matrix converter with reduced switch count

In this paper, single-phase control rectifier using single-phase matrix converter with reduced switch count is proposed. The proposed method is able to perform AC-DC converter operation using only six switches as perform by conventional single-phase matrix converter that uses eight main switches. The PWM technique was used to calculate the switch duty ratio to synthesize the output. Switch commutation arrangements were developed that allows dead time to avoid current spikes of non-ideal switches whilst providing a current path for the inductive load to avoid voltage spikes. The SPMC topology with reduced switch count can be easily control using suitable proposed switching algorithm. The feasibility of the proposed topology was verified by a computer simulation.

A control performance of linear model and the MacPherson model for active suspension system using composite nonlinear feedback

The purposes or functions of the commercial car suspension system are to take care on the car body weight, to isolate the car body from road profiles disturbance and to maintain the grip force between the wheel and road profiles. The Composite Nonlinear Feedback (CNF) control law is proposed in this comparative study between conventional linear model and Macpherson model. The control performance consists of velocity of car body, suspension deflection, wheel deflection and velocity of a car wheel. The main measurement in this study is the acceleration of the car body. The Linear Quadratic Regulator (LQR) and passive model are involved in this control performance is for comparison purposes. The mathematical model of linear model and MacPherson model are focused on the quarter car model active suspension system. The simulation work is done by using MATLAB and SIMULINK to see the control performance on the quarter car active suspension model. In this paper we can conclude that the CNF achieved the main objective of active suspension which is the ride comfort and road handling.

Skin detection based on thresholding in RGB and hue component

This paper presents a skin detection of color image using thresholding in hue component of HSV (Hue, Saturation, and Value) and RGB (Red, Green and Blue) color spaces. The reason for choosing hue component for thresholding compared to two other components is hue gives the best result for skin detection. The process of thresholding in hue component is done in order to get candidate pixels of skin regions. Then, the rectangular box of these blob regions are estimated and used to do thresholding in RGB color space where the mean and standard of each rectangular box is calculated. This method, is similar to adaptive thresholding technique in grayscale image processing, is able to detect the skin region of the test images accurately and with an acceptable robustness.

Automated measurements of power electronics research test rig for investigation of single-phase matrix converter operating as a controlled rectifier

This paper investigates and implement an automated measurement system for measuring power electronics research test rig based on single-phase matrix converter (SPMC) operating as a controlled rectifier. The output waveform of voltage and current are measured by an oscilloscope that is connected to a PC via a LabVIEW interface. The advantages of this method are its capability to process the data without the hassle of external aid and ability to record longer data length a limitation in normal oscilloscopes.

Vehicle stability enhancement based on second order sliding mode control

The vehicle handling and stability in emergency situation can be enhanced with direct yaw moment control (DYC). In this paper, a new controller using super twisting technique based on second order sliding mode control (SOSM) is proposed for the yaw moment control. The controller is designed based on two degree of freedom (2DOF) nonlinear model. The effectiveness of the proposed controller is compared to PI controller and conventional sliding mode controller by co-simulations in CarSim and Matlab/Simulink. The results show that the SOSM give better performance in tracking the desired response necessary for the vehicle handling and stability. In addition, the chattering phenomenon is also reduced, giving a smooth tracking trajectory.

Realization assessment of stabilizer with presonication on size-distribution of itraconazole nanoparticulate in wet-nanomilling

The paper investigates fabrication of itraconazole nanoparticulate in wet-nanomilling by appropriate alteration of the suspension properties and the milling parameters. By wet-nanomilling, stable nano-scale particulate can be prepared which have better physical properties. In this study, effects of adding stabilizer on nanoparticulate size and polydispersity index were performed during production of itraconazole nanoparticulate. In addition, the effect of pre-sonication followed by wet grinding was assessed on the particulate size of itraconazole in dispersion containing stabilizer. The size of drug particulate was reduced to less than 200nm with a polydispersity index (PDI) below 1.0 thus influencing the milling process under these conditions.

De-noising of noisy MRI brain image using the switching-based clustering algorithm

Magnetic Resonance Image is one of the technologies used for diagnosing brain cancer. Radiographers use the information obtained from MRI images to diagnose the disease and plan further treatment for the patient. MRI images are always corrupted with noise. Removing noise from images is crucial but it is not an easy task. Filtering algorithm is the most common method used to remove noise. A segmentation technique is normally used to process the image in order to detect the abnormality that has been observed, specifically in the brain. However, segmentation alone would be best to implement when the images are in good condition. In the case where the images are corrupted with noise, there are pre-processing steps that need to be implemented first before we can proceed to the next task. Therefore, in this project, we have proposed a simpler method that can de-noise and at the same time segment the image into several significant regions. The proposed method is called the switching-based clustering algorithm. The algorithm is implemented on the MRI brain images which are corrupted with a certain level of salt-and-pepper noise. During the segmentation process, the results show that the proposed algorithm has the ability to minimize the effect of noise without degrading the original images. The density of noise in the MRI images varies from 5% to 20%. The results are compared with the conventional clustering algorithm. Based on the experimental result obtained, the switching-based algorithm provides a better segmentation performance with fewer noise effects than the conventional clustering algorithm. Quantitative and qualitative analyses have shown positive results for the proposed switching-based clustering algorithm.