A review on micro-patterning processes of vertically aligned carbon nanotubes array (VACNTs Array)

Vertically Aligned Carbon Nanotubes array which are also sometimes labeled as carbon nanotubes forests have many applications in several engineering fields for its remarkable mechanical, electrical, optical, and thermal properties. The Vertically Aligned Carbon Nanotubes array is often employed in developing microdevices such as pressure sensor, angle sensor, switches, etc. To successfully integrate carbon nanotubes forest to the micro-electro-mechanical systems based devices micropatterning of the carbon nanotubes forest is required. There are several methods available to realize micropatterning of Vertically Aligned Carbon Nanotubes array, from in-situ patterning during the growth process to post-patterning process. Each has its advantages and disadvantages. This paper will discuss elaborately different patterning processes of the carbon nanotubes forest and their different characteristics

Virtual prototype-based kinematic modeling and simulation of a multi-mode amphibious robot

The amphibious robot, which has the capability of multi-mode motion, can maneuver diverse environments with high mobility and adaptability. These are employed in the area of reconnaissance, search and rescue operations, and monitoring. The existing amphibious robots have lower maneuverability over the crawling period on uneven and slope surfaces on the land. In this paper, a kinematic model of the amphibious robot based on virtual prototyping is designed for multi-mode locomotion. ADAMS (Automated dynamic analysis of mechanical systems) is a multi-body dynamic solver adopted to build the simulation model for the robot. The novel amphibious robot employs a Rockerbogie mechanism equipped with wheel paddles. The locomotion analysis on land involves straight-going and obstacle negotiation, which is simulated using ADAMS. The simulation analysis result demonstrates increased maneuverability, achieving a robot's velocity of robot 1.6 m/s. Normal forces on the front and rear wheels show equal load distribution, contributing more to the robot’s equilibrium over uneven terrain. The simulation result reflects the accurate kinematic characteristics of the amphibious robot and provides a theoretical basis for developing an algorithm for robot motion control and optimization. Further, this research will concentrate on the kinematic simulation maneuvering in water mode with the wheel paddle

Locomation strategies for amphibious robots-a review

In the past two decades, unmanned amphibious robots have proven the most promising and efficient systems ranging from scientific, military, and commercial applications. The applications like monitoring, surveillance, reconnaissance, and military combat operations require platforms to maneuver on challenging, complex, rugged terrains and diverse environments. The recent technological advancements and development in aquatic robotics and mobile robotics have facilitated a more agile, robust, and efficient amphibious robots maneuvering in multiple environments and various terrain profiles. Amphibious robot locomotion inspired by nature, such as amphibians, offers augmented flexibility, improved adaptability, and higher mobility over terrestrial, aquatic, and aerial mediums. In this review, amphibious robots' locomotion mechanism designed and developed previously are consolidated, systematically The review also analyzes the literature on amphibious robot highlighting the limitations, open research areas, recent key development in this research field. Further development and contributions to amphibious robot locomotion, actuation, and control can be utilized to perform specific missions in sophisticated environments, where tasks are unsafe or hardly feasible for the divers or traditional aquatic and terrestrial robots

Development of micro-EDM machine with process parameter control for EDM drilling

One of the demanding manufacturing processes nowadays is Micro Electrical Discharge Machining (Micro-EDM). Micro-EDM drilling is used largely in the aerospace industry, producing cooling holes into aero blades and other components. Typically, a commercial micro-EDM machine is costly, bulky, and not suitable for small business enterprise (SME). Therefore, the objective of this paper is to develop a single purpose micro-EDM machine that is compact, cost-effective and can be catered towards small business enterprise (SME). The newly developed EDM machine was designed based on three aspects: CNC router design, power supply design and gap width monitoring design. Subsequently, the developed machine was compared to a commercialized DT-110 MIKROTOOLS EDM machine based on the material removal rate and taperness through the micro-EDM drilling process. An interesting observation was that the MRR of the new micro-EDM machine increased with feed rate value while the DT-110 showed the opposite trend. Overall, the result showed that the new developed micro-EDM machine was capable to produce similar performances to the DT-110 machine in term of micro-EDM drilling application

Optical anisotropy in micromechanically rolled carbon nanotube forest

The bulk appearance of arrays of vertically aligned carbon nanotubes (VACNT arrays or CNT forests) is dark as they absorb most of the incident light. In this paper, two postprocessing techniques have been described where the CNT forest can be patterned by selective bending of the tips of the nanotubes using a rigid cylindrical tool. A tungsten tool was used to bend the vertical structure of CNTs with predefined parameters in two different ways as stated above: bending using the bottom surface of the tool (micromechanical bending (M2B)) and rolling using the side of the tool (micromechanical rolling (M2R)). The processed zone was investigated using a Field Emission Scanning Electron Microscope (FESEM) and optical setup to reveal the surface morphology and optical characteristics of the patterned CNTs on the substrate. Interestingly, the polarized optical reflection from the micromechanical rolled (M2R) sample was found to be significantly influenced by the rotation of the sample. It was observed that, if the polarization of the light is parallel to the alignment of the CNTs, the reflectance is at least 2 x higher than for the perpendicular direction. Furthermore, the reflectance varied almost linearly with good repeatability (~10%) as the processed CNT forest sample was rotated from 0° to 90°

Surface roughness modelling of the micromechanically patterned CNT forests

Introduction: A new method of modelling surface roughness of the resultant structure from various parameters in the microforming of CNT forests has been developed. One of the top-down microforming methods of CNT forests is called micromechanical bending (M2B). The method uses a high-speed rotating spindle to compact and flatten the surface of CNT forests. It results in the surface structure becoming smoother and increased reflectance of the surface. The reason for this phenomenon is the porosity that decreases by bending CNTs, hence preventing light from passing through. Moreover, the surface roughness is also significantly reduced. However, a study has yet to be conducted to estimate the theoretical value of surface roughness from the identified parameters. Aim: This research aims to develop an approach to model the surface roughness of resultant surface from a set of parameters in a micropatterning method. Methods: Experiments were conducted using a CNC machine to pattern onto CNT Forests using specific parameters, such as 1000, 1500, and 2000 rpm (spindle speed) with feed rates of 1, 5 and 10 mm/min. The step size was kept fixed at 1 μm for each level of the patterning pass. It was found that the periodic pattern of trochoidal mark was engraved on the surface, contributing to the value of measured surface roughness. Results: The results were compared with the theoretical value from the calculation of surface roughness using trochoidal motion with the assumption of the grain sizes of 0.2 μm, 0.3 μm, and 0.4 μm. The actual value of surface roughness was measured using the XE-AFM machine. The grain of 0.2 μm produced the same experimental trend with the theoretical value at rotational speeds of 1000, 1500, and 2000 rpm. However, the theoretical result was shifted downward because the surface could return to the original position due to the elastic properties of the CNTs, hence reducing the surface roughness. The best-fit result was reported for the grain of 0.4 μm, rotational speed of 2000 rpm, and speed rate of 1 mm/min, showing less than 1% difference

Optical resolver and method of use

The invention relates to a rotary system in general. More particularly, the invention relates to an optical resolver capable of measuring rotation angle of a rotating member for determining speed, displacement and direction

Application of CANFIS for modelling and predicting multiple output performances for different materials in μEDM

Micro Electrical Discharge Machining (μEDM) is one of the most demanding manufacturing processes available today. The selection of EDM parameters remains a challenge since it is frequently based on machinist intuition and heuristic approaches. Artificial intelligence algorithms have been used to model and predict the μEDM machining process in recent years. However, artificial intelligence has not been established for predicting μEDM performances based on material properties. Therefore, this paper has proposed a model that considers the material properties, such as thermal conductivity, melting point, and electrical resistivity. Since μEDM is a non-linear and stochastic process, Coactive Neuro-Fuzzy Inference Systems (CANFIS) was proposed to model and predict the multiple μEDM performances on various materials. The material properties, feed rate, capacitance, and gap voltage are input parameters in a three-level design based on a full factorial experiment. The CANFIS model can accurately predict the material removal rate (MRR), total discharge pulse, overcut, and taperness in a single model. The mean average percentage error (MAPE) of various outputs (predicted by the model) for test dataset such as MRR, total discharge pulse, overcut, and taper angle were found to be 4.5% (95.4% accuracy), 6.8% (93.2% accuracy), 15.4% (84.6% accuracy) and 15.2% (84.8% accuracy) respectively

Angular sensor

This discovery presents methods for angle measurement using CNT forests as a reflector which is first of its kind. The sensor comprised of partially polarized laser source, polarizer, patterned CNT forests and a photo detector to measure the transmitted polarized power coming through a polarizer. CNTs forest was patterned in two different ways, using bottom of the rotating tool and side of the rotating tool. It will generate two different types of surface, trochoidal motion type and anisotropic alignment in the direction of the tool motion. On the first sample, two measurement methods are described here, first by varying the polarization angle, Ɵ1 of the incident laser and second by varying the incident angle itself, Ɵ2. For the second sample, sample is rotated at its axis, Ɵ3 to see the difference in reflectance value

Prototype of single degree of freedom optical resolver

Optical resolvers are helpful for a wide variety of application, for example, automation and manufacturing industries. Different kinds of optical resolvers are available based on different material properties. In this paper, a prototype of a single Degree of Freedom optical resolver for measuring the angle of rotation is proposed. The device is based on the combination of the single wavelength (partially polarized) laser beam, a linear polarizer and a photodetector circuit is used for the rotational angle measurement. We present the result of sensitivity, accuracy and repeatability test to ensure the proper execution of single DOF optical resolver. The sensitivity of a single DOF optical resolver is around 0.467 V/degree and the standard deviation is 0.2 Volt. We obtained highly accurate and repeatable measurements according to the variation of the angle of the polarizer. Newly developed prototype optical resolver is cost effective, compact in size, no electromagnetic interference