Zahurin Samad

Development of a low-cost modular pole climbing robot

This article reports on the design and development work on a modular pole climbing robot. Modularity was achieved by ensuring similar repeated structures can be coupled and controlled in almost similar fashion. The design considers the rudimentary aspect of climbing and adopts grasp-push-grasp motion arrangement. The resulting design consists of two grippers for grasping and two central arms for climbing and lowering, all of which employs pneumatic cylinders. The whole climbing motion was achieved in six steps and the climbing speed is determined from the rate of filling the pneumatic cylinders involved. Parallel four-bar linkages arrangement was used to ensure the horizontal orientation of the grippers to prevent locking. The structure of the robot are made from aluminum with pin joints throughout to allow for easy assembly. PLC was used at this stage for the motion control. The developed robot can climb a 150 mm diameter pole at a speed of 0.6 m/min.

Design and modeling magnetorheological directional control valve

Directional control valves are designed to control direction of flow, while actuators maintain required speeds and precise positions. Magnetorheological (MR) fluid is a controllable fluid. Utilizing the MR fluid properties, direct interface between magnetic fields and fluid power is possible, without the need for mechanical moving parts like spools. This study proposes a design of a four-way three-position MR directional control valve, presents a method of building, and explains the working principle of the valve. An analysis of the design and finite elements using finite element method of magnetism (FEMM) software was performed on each valve. The magnetic circuit of the MR valve was analyzed and the performance was simulated. The experiment showed the functional working principle of the MR valve. In conclusion, the MR valve proved to be effective in controlling the direction and speed of hydraulic actuators proportionally. The proposed new design has the potential to reduce the complexity of directional control valves in the future.

Magneto-rheological directional control valve

The main part in hydraulic system is directional control valve. Directional control valve has complex construction such as moving spool to control the direction of actuator for required speed. Magneto-rheological (MR) fluid is one of controllable fluids. Utilizing the MR fluid properties, direct interface can be realized between magnetic field and fluid power without the need for moving parts like spool in directional control valves. This study proposes the design of four ways/three position MR proportional directional control valve (4/3 MR valve). The construction of valve and the principle of work are presented. Analysis for magnetic circuit and simulation for valve performance were done. The experiment was conducted to show the principle work of the valve functionally. Design and finite elements analysis using FEMM software of the MR valves were done to reach the optimal design. The valve works proportionally to control the direction and speed of hydraulic actuators. As the result, the optimal design of the valve achieved the optimum performance. The experimental result demonstrates the operation of 4/3 MR valve in 12 configurations. The 4/3 MR valve can replace many types of the spool directional control valve for controlling hydraulic actuator.

Error-based autofocus system using image feedback in a liquid-filled diaphragm lens

A liquid-filled diaphragm (LFD) lens system that uses image feedback for automatic focus control has been designed and developed. The edge slope width (ESW) of the pixel intensity profile across a binary target was selected as the focus measure parameter. An algorithm was developed to achieve single- and dual-direction autofocus control. An improved autofocus method, which is based on the error between the expected ESW value for a focused image and the ESW value for the current (unfocused) image, was introduced to improve the performance of the system. An empirical equation of the focus measure error was used to predict the number of autofocus operation steps required to approach a near-focus region. A stepper motor was used for actuating a syringe-driven pump mechanism that injects or withdraws fluid into (or out of) the fluid lens chamber. The lens diaphragm was made of polydimethylsiloxane (PDMS) polymer that covers the fluid chamber. A monochrome CCD camera was attached to the LFD lens to capture live images of the target. The autofocus experiments carried out using the new differential error-based algorithm proved the viability of the algorithm in determining the near-focus region. A maximum reduction of time operation was also recorded to be 40 s in comparison with the normal autofocus algorithm.

Finite element analysis and experimental validation of flashless cold forging of propeller hubs and blade of autonomous underwater vehicle

Abstract In this paper three-dimensional finite element method analysis and experimental flashless cold forging of aluminium front and back hubs, and the blade of an autonomous underwater vehicle propeller are presented. The rigid—plastic finite element simulation is performed using Deform F-3V6.0, to estimate the optimum load required for the flashless cold forging. The complex profiles of the hubs and blade are modelled using Solidworks SP4.02007, which is also used for the modelling of the workpiece and die-punch assembly. The workpiece used is of AISI AL6061 and the die material is die steel (AISI D2). The process is optimized to form the propeller back and front hubs, and the blade. For all the models, three workpieces with different specifications are selected and investigated to obtain the optimum workpiece that gives flashless cold forging with no underfilling. Based on the simulation results, the flashless cold forging is successfully done on a 100 tonne C-type machine. The experimental forged samples conform well with the simulated models.

Feasibility studies of Arduino microcontroller usage for IPMC actuator control

This paper investigates the usage of Arduino microcontroller to control closed loop of Ionic Polymer Metal Composite (IPMC) actuator response designed for compact underwater application. We demonstrate control of single IPMC actuator by PID controller using MATLAB/Simulink Arduino Input Output (ArduinoIO) support package. Experimental results show that the microcontroller able to differentiate response speed, stability and tracking error of different thicknesses of IPMC actuator when stimulated by multiple voltage waves and frequencies. Based on step signal and square waves tracking performance results, thinner IPMC (t1) has more than 5 times respond speed than thicker IPMC (t2). However, IPMC t1 has lower steady-state stability and more sensitive to external noise compared to IPMC t2 due to IPMC actuator mechanism factors and current Arduino setup limitation such as low sampling rate. For sinusoidal waves tracking analysis, IPMC t2 with lower frequency reference input shows minimum erms error (3.12 %), while IPMC t2 with higher frequency contains highest erms error (28.70 %). Therefore, added with further improvements in improving analog read sampling rate and analog write resolution, Arduino microcontroller can accurately control and analyse the IPMC actuator, thus manage to replace expensive and bulky current DAQ hardware.

Autonomous Underwater Vehicle Propeller Simulation using Computational Fluid Dynamic

Recently AUV development was stressed on improving the operation range and time. To achieve this requirement sufficient energy to propel and operate the device must be taken into consideration. However, the AUV power mainly supply by on board battery (Neocleous, and Schizas, 1999). Thus, the range of operation only depends on how much power it has. There are two options in order to improve the operation time, the first is developing very efficient battery and the second is optimized the AUV system either electrically or mechanically. For the first option, it takes time in order to develop very efficient battery. Then for time being, the second option is always selected by the researcher in order to improve the operation range of the AUV. Takinaci and Atlar, (2002) improved the energy power management in order to optimized the power consumption. Olsen, (2004) develops the optimum design of propeller that has less energy consumption but high thrust. Beside that Husaini, et al. (2009) work on AUV hull design by using numerical method to reduce the drag. As mentioned by Takekoshi, et al., (2005) AUV speed was affected by resistance force along the body. This resistance was due to drag force. Stanway and Stefanov-Wagner (2006) reported that the thrust produced by the propeller was quadraticly by increasing in propeller speed. This phenomenon can be understood by reviewing lifting line theory in Carlton, (2007). Although the thrust was increase in rotational speed, the torque also shows the same behavior Chen and Shih,(2007). In electrical point of view, this torque represents the shaft torque of the motor. This torque will introduced power output of the motor. From the theory that explained before, power consumption can be minimized by optimizing the propeller speed during operation. As mentioned in Olsen (2004) the power increases by increasing in speed. This is because to increase the speed of the vehicle more, thrust is needed. To increase the thrust, propeller speed must be increased. Thus, the power increases because the torque will be rise due to increasing in propeller speed. By knowing the power and thrust relationship, the developer is able to design the specific control system algorithm for certain task.

Precision Hole Making on Laminates Composite: Comparison between Drilling and Punching

Accurate and strong fastener assembly depends on precision of the hole. For structural material likes composites, these criteria is very important. Drilling is the most common method in producing hole on composites. But the main problem of drilling is excessive tool wear that may affect the quality of the holes. Punching is another alternative in making a hole. The main objective of this study is to compare between drilling and punching in terms of hole quality. The scanned images of the produced hole will be captured using commercial 3D optical surface measurement method namely Alicona IFM. The effect to the quality of the produced hole will be measured and compared between drilling and punching.

2D Contractile Water Jet Thruster Characterization for Bio-Inspired Underwater Robot Locomotion

This research was conducted to analyze the thrust performance generated from a two dimensional contractile water jet thruster (CWJT). The main aim of this research is to investigate the relation and reaction between the input parameters of the contractile water jet thruster. The major parameter of this study is the actuating force as the input and the thrust force as the output. In addition to these parameters, nozzle area and fluid velocity influence were also considered in the investigation. Two pneumatic cylinders were applied to actuate the contraction. Thrust force was measured by both experimentally and theoretically. Generally the increment of the contraction force increases the thrust force. However, generated thrust at different contraction force depends on the size of the nozzle.

Fabrication and Characterization of IPMC Actuator for Underwater Micro Robot Propulsor

The usage of Ionic Polymer-Metal Composite (IPMC) actuator as the propulsor for underwater robot has been worked out by many scientists and researchers. IPMC actuator had been selected due to its advantages such as low energy consumption, low operation noise and ability to work underwater. This paper presents the fabrication and characterization of the IPMC actuator. The IPMC actuator samples had been fabricated using electroless plating for three different thickness and lengths. The characterization was conducted to determine the influence of the thickness, length, input frequency, drive voltage and orientation angle on the tip force and output frequency. The results show that IPMC thickness has significant influence on the tip force generation and lower input frequency would results wider displacement. The recorded results are essential as future reference in developing the propulsor for the underwater robot.