Abstract: This paper investigated the positioning control performance of a two-degree-of-freedom (2-DOF) robotic finger mechanism to achieve precision motion control as an initial study towards developing a multi-fingered robotic hand system. Previous research has shown that behaviours such as instability, large steady-state error and poor transient performance often occur in the robotic hand mechanism. Therefore, this paper described the design of a 2-DOF robotic finger mechanism, which was then compared with the performance of several controllers by Point-to-Point (PTP) positioning control. The proposed controllers relied on the angular position control of each motor joint, (i.e. the position control of the 2-DOF robotic finger mechanism). The closed-loop system for an uncompensated and compensated system were used in this study with several reference angles. Three different control strategies namely; (i) Proportional Integral Derivative (PID) controller (ii) Fuzzy Logic controller (FLC) and (iii) Linear Quadratic Regulator (LQR) controller were selected for comparison via simulation and in performing the experimental work. The controller results were validated by Point-to-Point (PTP) positioning control at different reference amplitudes. From the results, the FLC was found to provide optimal performance with a higher level of adaptability for the PTP positioning control with improvements in both response time by 97.9% (0.075 s) and steady-state error by 99.5% (0.01°) compared to the uncompensated system.

Abstract: This paper presents the design and experimental testing of an energy harvesting (EH) device that can harvest human motion energy at low frequency and wide bandwidth using the vibration absorber mode. Based on the concept of the 2-DOF vibration system, the parameters namely; the proof masses and spring constants for maximizing the power output, are selected to harvest energy at low frequency (1-10 Hz) and wide bandwidth (± 20% of the mean frequency), which matches the human motion. The piezoelectric layer used is polyvinylidene fluoride (PVDF) which portrays favorable characteristics. A finite element model is developed in COMSOL to investigate the system performance with the selected parameters. Experimental work is then carried out to validate the design with the selected parameters and investigate the system performance. The designed energy harvester prototype is expected to generate low power in the order of micro-watts to milli-watt in a range of frequencies between the system’s two resonant frequencies. This amount of power is sufficient enough to provide additional power for wearable devices and medical implants.

Abstract: Wind turbines are important in capturing power from varying wind speed. For maximum energy capture in low wind speed regime, a standard generator torque controller is normally used to track the incoming wind speed in order to maximize power production. In low wind speed regime, the rotor blade pitch angles are held constant at an optimum value that ensures maximum lift. This control strategy has some limitations, especially in large wind turbines due to induced structural loads. Though aerodynamic loads are not high in the low wind speed regime, maximum power point tracking can cause high torque variations in the drive-train which can lead to early fatigue failure of the wind turbine. Most studies done in this regime focuses on maximum energy capture, without considering structural loads, which are critical in large wind turbines that have large inertial loads. In this paper, a multi-objective control strategy that ensures utility scale wind turbines capture maximum power in low wind speed regime, while minimizing drive-train vibrations is proposed. An optimal generator torque controller is designed to achieve maximum energy capture, while an independent blade pitch controller is designed to reduce drive-train vibrational loads in the wind turbine. The two controllers are designed in MATLAB and simulated in Fatigue, Aerodynamics, Structural and Turbulence (FAST) software. TurbSim full-field turbulent wind simulator is used to generate varying wind profiles for simulation purposes. A fictitious 1.5 MW WindPACT wind turbine model is used to evaluate the proposed control strategy. When evaluated against a baseline controller for the low wind speed regime under stochastic wind excitation, the multi-objective control strategy improves drive-train torsional damping by 2.69%, with standard deviation decreasing by 3.28%, without compromising on power capture.

Abstract: Metal composite stacks such as stainless steel-glass fiber reinforced polymer or stainless steel-GFRP stacks can be considered as an innovative structural configuration in the manufacturing industry. Several industrial applications require holes to be drilled out in the stacked materials for assembly purposes. The high quality holes in stainless steel-GFRP stacks could be achieved by minimizing thrust force (Fz) and torque (Mz) of the drilling process, as well as the hole surface roughness (SR) and delamination (D). The drilling sequence strategy was drilling from stainless steel to GFRP. In this case, Fz and Mz were measured during stainless steel drilling process. The measurements of SR were also done in the holes of stainless steel, while the D measurements were performed in the GFRP’s holes. In this study, the minimization of Fz, Mz, SR, and D has been conducted by applying back propagation neural network (BPNN) combined with genetic algorithm (GA) optimization method. The drilling experiments were carried on by utilizing a full factorial 3x3x3 design of experiments. The varying drilling parameters were spindle speed, feed rate, and drill point angle. The quality characteristics of Fz, Mz, SR, and D were smaller the better. BPNN was first performed to obtain the modeling of drilling experiment and a prediction of optimum drilling responses. GA was then executed to attain the best combination of drilling parameters levels that would minimize Fz, Mz, SR, and D. The influence of spindle speed, feed rate, and drill point angle on responses was performed by reviewing the response graphs. The outcome of a confirmation experiment disclosed that the integration of BPNN and GA manage to substantially enhance and predict the multi-performance characteristics accurately.

Abstract: Hybrid synthetic-natural polymer matrix composites (HSNPMCs) are becoming more important and attractive for many structural applications. Partial replacement of synthetic fibres (SFs) with natural fibres (NFs) are an interesting subject for engineers considering the environmental awareness and cost reduction. In this study, the glass/jute fibre-reinforced polyester composites were fabricated with different jute-to-glass content ratios while keeping the same fibre weight fractions that equal to about 18% for all composites. The mechanical tests like tensile, flexural, and absorbed energy (Charpy impact test) were conducted for glass, jute, and hybrid composite specimens and compared among each other. Free vibration analysis was carried out to these composite specimens to find their fundamental natural frequencies and damping ratios. The results indicated that hybrid composites with a stacking sequence of G-J-G exhibited promising tensile and flexural properties and good absorbed energy. Concerning the free vibrational characteristics, the G-J-J-G composite type offered the highest fundamental frequency with good dampening characteristics. Higher benefits could be obtained when using specific mechanical properties and vibrational characteristics of hybrid composites when compared with glass composites. It can be suggested that the incorporation of jute fibres into the glass fibre composite in hybrid structure, as presented in this study, can improve the dynamic characteristics of the composites with encouraging mechanical performance.

Abstract: This paper proposes an experimental-based approach to estimate the kinematic parameters and develop a cascade controller of a Cartesian robot. The aim is to satisfy the position accuracy in the trajectory execution, guaranteeing a high dynamics. The proposed procedure consists of a set of experimental tests executed on a reference trajectory, varying the velocity and acceleration in a specific range. The model is based on the Least-Square-Estimation and the Genetic Algorithms. Once the kinematic parameters have been calculated and evaluated, the controller has been built using an iterative procedure to estimate the PID gains of the position, velocity and current loops. Finally, the overall system has been validated through a set of reference trajectories, comparing the observed results with the predicted values. The RMSE index of torque has shown a congruence between the obtained results with a maximum value lower than 8.0 Nm.

Abstract: This paper presents a model-driven control implementation, which is derived from the Model-Based Systems Engineering (MBSE) approach combined with the Unified Modeling Language (UML)/Systems Modeling Language (SysML), the specification of the Unscented Kalman Filter (UKF) algorithm and hybrid automata in order to conveniently realize and deploy controllers for quadrotor Unmanned Aerial Vehicles (UAVs). The study is step-by-step carried out by the adaptation of quadrotor UAV dynamics and control structure, which are then combined with the specialization of MBSE features as follows: the object-oriented analysis model is defined by the specification of use-case model combined with hybrid automata to closely gather the requirement analysis for control; the object-oriented design model is then built on the defined analysis with the real-time UML/SysML’s features enclosed with the timing concurrency of evolution, in order to intensively design structures and behaviors for the controller; the detailed object-oriented design model is next converted into the object-oriented implementation models by using open-source platforms to quickly simulate and deploy the quadrotor UAV controller. Following this proposed model, a trajectory-tracking controller, which permits a quadrotor UAV to reach and follow a reference trajectory, was completely deployed and successfully taken on trial flights.

Abstract: Unlike the conventional machine tool, laser radiation does not experience tool wear and tool hardness does not impact the machining speed. LBM relies entirely on the optical characteristics of the laser beam, and thermo-physical characteristics of the workpiece. In LBM, however, it is still a challenge to determine the best process variables for a particular material. Inappropriately chosen parameters can lead to low material removal rate, large heat affected zone, poor geometry of cutting and poor surface finish. This research aimed at optimizing the LBM process of acrylic sheet for best material removal rate, kerf width and kerf depth. To accomplish this, the impact of machining parameters such as power, machining speed, focal length on process performance were investigated. Experiments were conducted by setting different values of these parameters. After that an Artificial neural network (ANN) model was created, trained, tested and validated with the experimental obtained data using MATLAB. The ANN model after being deployed to Simulink was used to predict the level of kerf width, kerf depth and material removal rate for specific level of speed, Power and focal length outside the domain of experiment and training input. Moreover, ANOVA analysis was used to study the effect of input parameters over output parameters. Finally, Gray relational analysis (GRA) was used to get the most optimum output, that is maximum material removal rate (MRR), minimum kerf width and kerf depth of 5 mm. Upon completion of this research, Validation experiments were conducted, these experimental results showed conformity to the optimal conditions obtained using the ANN and GRA.

Abstract: The main parameter influencing the increase in the performance efficiency of the Savonius wind turbine is the geometry of the blade shape. Therefore, a lot of research has been done on developing and improving this parameter. In this study, a series of numerical tests were performed on the Savonius wind turbine by means of a 2D unsteady simulation (CFD Fluent) to the validation of the experimental results of the elliptical Savonius turbine and also to test different types of turbulence models which are Standard k-ω, (SST) k-ω, Standard k-ϵ and Realizable k-ϵ. After that, the new model is developed by changing the internal surface of the concave blade to increase its surface area (wavy shape) and it is experimental tested in the open wind tunnel with wind velocity (6 m/s, 9 m/s) and record the maximum power coefficient was (0.296) with the tip speed ratio (0.72). The new blade design showed a better performance than the classical elliptical Savonius turbine model.

Abstract: Composite materials reinforced using natural fibers have great intense in the last few years, due to their advantages to health and it is considered a friendly environment. Nowadays, the date palm trees are attractive, especially in the middle east region, this is due to their widespread which make them cheap and available with a large amount. The date palm trees are used in ancient years in many simple industries such as ropes, scuttle …etc. In the present study date, palm trees have been used to reinforce epoxy resin to be used in advanced industrial applications. Firstly, three different types of chemical treatments are carried out on the date palm trees; the fibers are immersion in three different types of a chemical solution (CH3COOH, HCl, and alkaline NaOH) with three different concentrations 10% and 20 % and 50 % at boiling temperature for 1 and 2hrs. Then, these fibres are mechanically grinding to small chipped fibres. These fibres are mixed with epoxy resin. The effect of chemical treatment in the date palm trees fibres is analysis using electro-scan microstructure (SEM) examination. The tensile test is carried out over the standard tensile test specimens of that composite to study the effectiveness of reinforcement with the epoxy resin. The resistance to fracture and to crack propagation are investigated measuring surface release energy of each composite specimen of date palm trees fibres reinforced epoxy (DPTFRE). The fracture properties are measured using standard composite compact tension test specimen at room temperature. The maximum and minimum values of tensile, crack resistance are measures. The results show that HCl treatment gives good compatibility with date palm trees fibres.

Abstract: Osteogenesis imperfecta (OI) is a fragile bone disease characterized by easy fractures. The femur consists of cortical and cancellous bone, each with different mechanical properties. Bone fractures often occur throughout patients’ lifetime. However, doctors still have no quantitative method to predict fractures. Therefore, this project’s purpose is to investigate the OI femoral fracture risk to help prevent fractures. The project consists of three sections; cortical and cancellous segmentation, reconstruction of 3D OI femoral model and finite element analysis (FEA) of the OI femur to obtain fracture risk. The fracture risk in daily activities and the fracture load were examined. All the stress values were judged by the fracture criteria, assumed as 115 MPa. The exercises that exerted force more than 6 times of body weight can cause fractures. In addition, the optimal compressive force and tensile force were 919.7 N and 912.1 N, respectively, while medial and lateral impact were 230.8 N. Cancellous bone was not affected even a fracture happen. Based on these findings, we can conclude that when the OI femur is subjected to lateral or medial forces, the femur breaks easily. The bone can be reconstructed into a solid body without having to separate bone into cortical and cancellous.

Abstract: This paper presents a robotic gripper design which relies on flexural joints rather than prismatic and revolute joints to ensure gripping action. The designed flexure-based gripper exhibits large displacement that fall within the millimetre scale range. With large displacements, the gripper is used to handle kiwifruit and at the same time determine its softness for sorting purposes. Flexural joint grippers with kiwifruit-size range of displacement are currently non-existent in the industry. Flexural joint mechanism is based on the intrinsic compliance of a material to achieve structural elastic deformation to achieve displacement. The gripper is monolithic in nature to properly accommodate flexure joints and also any further works in microelectronics process integration. The monolithic model exhibits more lumped compliancy displacement than distributed compliancy. The feasibility of the design is examined through a series of numerical analysis and simulations on COMSOL platform. Crucial design standards factored in are low fabrication and material costs, parallel gripping motion of fingers, large finger displacement, low joint stress concentrations and low output forces. A prototype is realised through subtractive fabrication of the prototype. Through a series of experiments the maximum range of motion for the gripper is found to be 20mm, half of which is contributed by each finger. Another set of experiments were done to investigate whether the gripper can accurately affirm the softness of the manipulated kiwifruits. The flexural gripper was able to successfully grasp and manipulate kiwifruit, at the same time determining fruit softness.

Abstract: This paper focuses on theoretical design and experimental investigation of multiple hydraulic actuators used for precise positioning of elements in a reconfigurable assembly fixture. Design analysis of the hydraulic system is achieved by deriving mathematical models of the components. A physical model of the hydraulic system was developed in SimHydraulics using Matlab-Simulink. The developed model was parameterized using the result obtained from the design analysis. The responses of the actuators were obtained for different input signals at the directional control valves. Experiment was carried out on an electrohydraulic test bench in order to observe the performance of the system, and confirm the synchronized extension and retraction of the actuators. Results obtained from the simulation and experiment are presented graphically and discussed extensively.

Abstract: The paper aims to develop the finite element (FE) models of tibia with Osteogenesis Imperfecta (OI) based on a patient-specific computed tomography (CT)-images. Two types of FE model have been developed. The first model was set the tibia bone as a single solid model whereas the second model consists of cortical bone and cancellous bone. The developed FE models were used for FE analysis using Voxelcon under various loadings, and then the results of the different models were compared. It was found that the single model yields relatively in agreement to piecewise model, with percentage different of below than 2% for all loading conditions. It seems that the reconstructed FE model considering the cancellous bone did not give significant effect compared to the solid model that neglecting the microstructure of cancellous bone. Hence, we can conclude that the single solid FE model with OI has predicted well, at least for the present boundary conditions, although the cancellous bone was neglected in the model reconstruction.