Mohd Azizi Abdul Rahman

A Review of Classification Techniques of EMG Signals during Isotonic and Isometric Contractions.

In recent years, there has been major interest in the exposure to physical therapy during rehabilitation. Several publications have demonstrated its usefulness in clinical/medical and human machine interface (HMI) applications. An automated system will guide the user to perform the training during rehabilitation independently. Advances in engineering have extended electromyography (EMG) beyond the traditional diagnostic applications to also include applications in diverse areas such as movement analysis. This paper gives an overview of the numerous methods available to recognize motion patterns of EMG signals for both isotonic and isometric contractions. Various signal analysis methods are compared by illustrating their applicability in real-time settings. This paper will be of interest to researchers who would like to select the most appropriate methodology in classifying motion patterns, especially during different types of contractions. For feature extraction, the probability density function (PDF) of EMG signals will be the main interest of this study. Following that, a brief explanation of the different methods for pre-processing, feature extraction and classifying EMG signals will be compared in terms of their performance. The crux of this paper is to review the most recent developments and research studies related to the issues mentioned above.

A high performance magnetorheological valve with a meandering flow path

The huge developments in the field of magnetorheological (MR) fluid-based devices will have a great influence on the future of mechatronic applications due to the ease of interfacing between electronic controls and the mechanical components that they provide. Among various MR fluid-based devices, an MR valve would be particularly significant for the development of other devices, if it could be successfully achieved. One of the most challenging obstacles to MR valve development is the difficulty of achieving device miniaturization while, at the same time, improving the achievable performance. This study demonstrates a novel design for an MR valve, using the meandering flow path approach in order to increase the effective area so that the MR fluid can be regulated within a small-sized valve. The meandering flow path is formed by combining multiple annular, radial and orifice flow channels. In order to analyze the valve performance, a mathematical model of the proposed MR valve is derived and combined with numerical simulation using the finite element method, with the intention of predicting the achievable pressure drop that can be generated by the valve. The predicted MR valve performances are then experimentally evaluated using an oscillation-disturbed bypass hydraulic cylinder. The simulation results show that the proposed MR valve design could yield substantial pressure drop improvement, which is confirmed by the experiment.

Model-Based Development and Simulation for Robotic Systems with SysML, Simulink and Simscape Profiles

In system-level design, it is difficult to achieve a system verification which fulfils the requirements of various stakeholders using only descriptive system models. Descriptive system models using SysML alone are insufficient for system behaviour verifications and engineers always use different simulation tools (e.g., the Mathworks Simulink or Modelica Dymola) to analyze systems behaviour. It is a good idea to combine descriptive and simulation models. This paper presents the development of a collaborative design framework which brings SysML, Simulink, and Simscape profiles within the domain of robotics. A conceptual design method is proposed to support execution models for simulation. In brief, the descriptive SysML system-level model is interpreted into the system-level simulation models (e.g., Simulink and Simscape). We then use a plugin-based model integration technique to keep both models in sync for automatic simulation. A simulation study is performed to evaluate the system. To illustrate the design of this system, we present a simulated closed-loop system.

Model-Based Detection and Tracking of Single Moving Object Using Laser Range Finder

Autonomous vehicles navigation in urban area suppose to deal with static and dynamic objects. To ensure safe autonomous navigation, the detection accuracy of a moving object is very critical to avoid false alarm while tracking the direction of moving object for collision avoidance. This paper presents the experimental results of the proposed Detection and Tracking Moving Object (DATMO) algorithm for a single moving object. Experiments were conducted in outdoor environment using a vehicle equipped with a laser range finder to provide the input data to the DATMO algorithm while the Kalman filter with the integration of constant velocity (CV) model was used for tracking. The results from the experiments showed that the DATMO algorithm developed successfully tracks a single moving object in an outdoor environment.

Bypass Rotary Magnetorheological Damper for Automotive Applications

A novel concept of bypass rotary Magneto-rheological (MR) damper is studied in the automotive suspension application. The proposed design is developed based on a vane-type damper structure with an MR control valve located outside of the damper. The design is intended to enhance the ease of maintenance and to reduce the thermal effect from the coil to the MR fluid. The valve is the key component of the damper that exploits the advance characteristics of MR fluid in which have sensitive rheological properties to magnetic field. The ability of the valve to modify the strength of magnetic field has given an advantage that the valve can be operated without any moving parts. The elimination of these parts in the throttling mechanism of the valve will provide benefit in terms of product lifetime and responsiveness. The main objective of this paper is to elaborate the advantages of the bypass rotary MR damper and to demonstrate the damper performance through force-velocity characteristics. The analytical model of the damper is developed and used in the determination of the force-velocity curves and the equivalent damping coefficients.

Model-Driven Development of Intelligent Mobile Robot Using Systems Modeling Language (SysML)

In Japan alone the number of disabled and elderly people are growing rapidly and they usually require personal transportation vehicles such as cars and wheelchairs. However, people currently have limited capabilities or difficulties to operate these vehicles in such complex environments like shopping malls or tourist-attraction centers. In recent years, a great number of studies of mobile robot applications have been proposed. However, only few of these studies have realized the model-based design approach in their entire development process. NEDO’s Intelligent Robot Technology (RT) Software project (Okano et al.,2009) started to promote the robot technology as the basic knowledge and technology to solve various problems in daily life. In this context, an intelligent mobile robot has been developed for providing mobility to the elderly and physically unfortunate people. Besides that, the National Institute of Advanced Industrial Science and technology, also known as AIST has developed the RT-Middleware (RTM) in order to achieve efficiency in developing robot software components (Ando et al., 2005). The main idea of this research is to develop robot software modules by looking from the system engineering analysis point of views. This is because most robotic systems are complex embedded systems. System engineering approaches focus on designing and constructing the complete system, and also on providing model reuse capabilities. Moreover, these approaches can enhance communications among the development teams, specification and design qualities and reuse of system specification and design artifacts. Modules’ reusability is our main concern in this paper. Past development efforts of robot software using Model Driven Architecture (OMG MDA, 2003) Model Driven Architecture® (OMG MDA, 2003) approach seem insufficient to support the demand of current industrial-to-domestic robot transitions. Developing intelligent robots in large scales is very demanding for experiment purposes. Thus, almost all robot systems have some common functions. However, much usable design information went to waste because of a serious lack of sharing and reusability. This motivates us to explore the

Robust attitude control design for a low-cost hexarotor micro aerial vehicle

This article proposes a new practical robust attitude state feedback controller of a low-cost hexarotor micro aerial vehicle under the effects of noise in angular velocity measurements and multiple uncertainties (called the equivalent disturbance), which consist of external time-varying wind disturbance, nonlinear dynamics, coupling and parametric uncertainties. The proposed method is designed in two simple steps. Firstly, a nominal cascade controller is designed to reduce noise in angular velocity measurements and to achieve good attitude tracking performance in nominal conditions. Then, a second-order robust compensator is integrated into the closed-loop system to reduce the effects of the equivalent disturbance. The proposed control design is a linear time-invariant controller which is easily implemented in practical applications. Compared to other advanced attitude controllers, the proposed controller incurs lower computational costs and can easily be implemented in a low-cost embedded microcontroller system. In addition, a practical computational design procedure and an intuitive online tuning method for the proposed controller are presented in this article in order to provide a complete reference to micro aerial vehicle developers. The simulation and experimental results are presented to demonstrate the robustness of the proposed controller in operation in outdoor environments, to show good steady-state and dynamic tracking performance of the closed-loop system and to prove that the tracking errors are ultimately bounded within desired limits.

Electrocardiographic (ECG) and Electromyographic (EMG) signals fusion for physiological device in rehab application

In this paper, a preliminary work on improving fitness for the post-stroke rehab application is investigated. For this purpose, a fusion of the Electrocardiographic (ECG) and Electromyographic (EMG) biosignals is proposed to produce a significant control signal and to achieve a biosignals multimodal fusion system. In this work, a mathematical approach such as the Bayesian network will be applied in order to combine both ECG and EMG biosignals. Furthermore, the significant fused elements can be applied to manipulate the control of physiological devices (PDs) for emulating the classic rehabilitation exerdse (e.g., cycling). Consequently, the proposed method for a multimodal fusion of muscle contractions for heart and lower limbs shall give improvement on monitoring the rehabilitation progress with better accuracy for signals fusion.

Effect of leader information broadcasted throughout vehicle platoon in a constant spacing policy

The constant spacing policy is a strategy to design longitudinal controller for vehicle platoon. The inter-vehicle spacing distances are set to be constant between consecutive cars in the platoon and independence with vehicle speed. The additional communication link in cooperative adaptive cruise control (CACC) structure, make it worth to be revisited to study the improvement that can be offered. The unstable string behavior of this strategy can be overcome with this new communication structure. In this paper, we use one of the communication structure, with leading vehicle speed and acceleration information been broadcasted throughout the platoon. The simulation result in homogenous traffic scenario has been presented and the performance of this structure has been analyzed. The improvement in string stability and small inter-vehicle spacing distance has also been discussed.

Modular design of artificial potential field and nonlinear model predictive control for a vehicle collision avoidance system with move blocking strategy

The collision avoidance (CA) system is a pivotal part of the autonomous vehicle. Ability to navigate the vehicle in various hazardous scenarios demands reliable actuator interventions. In a complex CA scenario, the increased nonlinearity requires a dependable control strategy. For example, during collisions with a sudden appearing obstacle (i.e. crossing pedestrian, vehicle), the abrupt increment of vehicle longitudinal and lateral forces summation during the CA maneuver demands a system with the ability to handle coupled nonlinear dynamics. Failure to address the aforementioned issues will result in collisions and near-miss incidents. Thus, to solve these issues, a nonlinear model predictive control (NMPC)-based path tracking strategy is proposed as the automated motion guidance for the host vehicle CA architecture. The system is integrated with the artificial potential field (APF) as the motion planning strategy. In a hazardous scenario, APF measures the collision risks and formulates the desired yaw rate and deceleration metrics for the path replanning. APF ensures an optimal replanned trajectory by including the vehicle dynamics into its optimization formulation. NMPC then acts as the coupled path and speed tracking controller to enable vehicle navigation. To accommodate vehicle comfort during the avoidance, NMPC is constrained. Due to its complexity as a nonlinear controller, NMPC can be time-consuming. Therefore, a move blocking strategy is assimilated within the architecture to decrease the system’s computational burden. The modular nature of the architecture allows each strategy to be tuned and developed independently without affecting each others’ performance. The system’s tracking performance is analyzed by computational simulations with several CA scenarios (crossing pedestrian, parked bus, and sudden appearing moving vehicle at an intersection). NMPC tracking performance is compared to the nominal MPC and linear controllers. The effect of move blocking strategies on NMPC performance are analyzed, and the results are compared in terms of mean squared error values. The inclusion of nonlinear tracking controllers in the architecture is shown to provide reliable CA actions in various hazardous scenarios. The work is important for the development of a reliable controller strategy for multi-scenario CA of the fully autonomous vehicle.