Samir Mekid

A review of machine tool accuracy enhancement through error compensation in serial and parallel kinematic machines

The accuracy of machine tools is a critical factor that affects the quality of manufactured products which is one of the most important considerations for any manufacturer. The consistent performance of the machine tool is constrained by the errors built in the machine (e.g., assembly error) or occurring on a periodic basis on the account of change in temperature and cutting forces. A number of studies have been conducted to identify, predict and compensate these errors to improve machine tools accuracy. This paper reviews these studies extensively and identifies the issues and challenges for machine tool accuracy enhancement leading to zero defects parts.

Foresight formulation in innovative production, automation and control systems

Purpose – This paper aims to define imminent and future key aspects in innovative production machines and systems but more specifically to focus on the automation and control aspects.Design/methodology/approach – The foresight analysis is based on the state‐of‐the‐art of current manufacturing technologies with a setup of key enabling features and a roadmap research.Findings – The paper finds that more integration of current and future technology development is required to build a strong platform for various applications featured with interoperability, trust, security and protection. Autonomy and close collaboration aspects in machines remain as crucial targets for the near future. An immediate action is required on smart strategies for the design patterns and agents to enable intuitive components for high quality dynamic user interfaces. This will allow rapid configuration and adaptation to new manufacturing tasks with highly improved machine learning.Originality/value – The paper describes the future of ...

Radio Frequency Energy Harvesting Characterization: An Experimental Study

This paper presents the outcomes of experiments performed to acquire data and to evaluate various parameters to: (1) assess the feasibility of harvesting the energy from the ambient RF power to energize wireless sensor nodes, and, (2) characterize commercially available PowerCastTM energy harvester. The parameters of interest are: (1) Ambient RF power along several bands, (2) Time, Tc, taken by PowerCastTM energy harvester for charging, and (3), The received signal strength indicator (RSSI) captured by PowerCast™ energy harvester. The former measurements are taken at different locations inside King Fahd University campus. The latter two quantities were computed from data acquired at various coordinates of the harvester relative to the transmitter and the source of energy. The data is acquired in indoor and outdoor scenarios. The acquired data was processed in MATLAB and it was concluded that: (1) The ambient RF power in not sufficient to energize the commercially available PowerCast™ RF power harvester which has a specified requirement of at least -10dBm power to successfully harvest RF energy. (2) The outdoor experiments suggested that Tc is directly, while RSSI is inversely proportional to the radial distance from the power transmitter. The two quantities are also significantly affected by the variation of azimuth and elevation of harvester w.r.t. the transmitter. (3) It is observed in the indoor experiments that trends of Tc and RSSI are not as regular as those in the case of outdoor experiments. Experimental procedure and all of the analyses are documented in detail so that it can be a useful reference for researchers working in this area.

Design strategy for precision engineering: second-order phenomena

To obtain higher precision and accuracy in mechanical systems, a design strategy is presented in this paper including both mechanical and servo-control design methodologies to ensure higher controllability and compensation of errors due to non-modelled phenomena. Examples of physical phenomena and modelling problems that may affect the accuracy at the second order are also presented.

Relay node placement in wireless sensor networks for pipeline inspection

Wireless sensor networks (WSNs) provide an effective approach for underground pipeline inspection. Such WSNs comprise sensor nodes (SNs) and relay nodes (RNs) for information sensing and communication. WSNs can perform accurate and realtime inspection, especially in adverse environments. However, transmitting information between underground and aboveground nodes is very challenging. First, in-pipe SNs conducting controlled maneuvers underground are mobile. Second, SNs need to transmit the information wirelessly to aboveground base stations (BSs). In addition, radio propagation is complex because radio waves travel in a multi-medium environment. Finally, the SNs have limited energy supply. Therefore, proper deployment of a WSN is critical to providing reliable communications and efficient inspection. This paper presents a channel-aware methodology for deploying aboveground RNs in WSNs for underground pipeline inspection. Specifically, first, the paper provides a path loss model for radio propagation over multiple transmission media. Then, based on the path loss model a method is developed for optimum placement of the RNs so as to minimize the energy use of SNs and allow reliable communications. This method takes into account characteristics of the wireless channels, power consumption constraint, pipeline coverage requirement, and the limit of the number of the RNs. We provide an algorithm for optimization of RN placement and SNs power consumption. Simulation results show the efficacy of the proposed framework.

Optimal coverage of an infrastructure network using sensors with distance-decaying sensing quality

Motivated by recent applications of wireless sensor networks in monitoring infrastructure networks, we address the problem of optimal coverage of infrastructure networks using sensors whose sensing performance decays with distance. We show that this problem can be formulated as a continuous p-median problem on networks. The literature has addressed the discrete p-median problem on networks and in continuum domains, and the continuous p-median problem in continuum domains extensively. However, in-depth analysis of the continuous p-median problem on networks has been lacking. With the sensing performance model that decays with distance, each sensor covers a region equivalent to its Voronoi partition on the network in terms of the shortest path distance metric. Using Voronoi partitions, we define a directional partial derivative of the coverage metric with respect to a sensors location. We then propose a gradient descent algorithm to obtain a locally optimal solution with guaranteed convergence. The quality of an optimal solution depends on the choice of the initial configuration of sensors. We obtain an initial configuration using two approaches: by solving the discrete p-median problem on a lumped network and by random sampling. We consider two methods of random sampling: uniform sampling and D^2-sampling. The first approach with the initial solution of the discrete p-median problem leads to the best coverage performance for large networks, but at the cost of high running time. We also observe that the gradient descent on the initial solution with the D^2-sampling method yields a solution that is within at most 7% of the previous solution and with much shorter running time.

Towards sensor array materials: can failure be delayed?

Abstract Further to prior development in enhancing structural health using smart materials, an innovative class of materials characterized by the ability to feel senses like humans, i.e. ‘nervous materials’, is discussed. Designed at all scales, these materials will enhance personnel and public safety, and secure greater reliability of products. Materials may fail suddenly, but any system wishes that failure is known in good time and delayed until safe conditions are reached. Nervous materials are expected to be the solution to this statement. This new class of materials is based on the novel concept of materials capable of feeling multiple structural and external stimuli, e.g. stress, force, pressure and temperature, while feeding information back to a controller for appropriate real-time action. The strain–stress state is developed in real time with the identified and characterized source of stimulus, with optimized time response to retrieve initial specified conditions, e.g. shape and strength. Sensors are volumetrically embedded and distributed, emulating the human nervous system. Immediate applications are in aircraft, cars, nuclear energy and robotics. Such materials will reduce maintenance costs, detect initial failures and delay them with self-healing. This article reviews the common aspects and challenges surrounding this new class of materials with types of sensors to be embedded seamlessly or inherently, including appropriate embedding manufacturing techniques with modeling and simulation methods.

Fiber-Embedded Metallic Materials: From Sensing towards Nervous Behavior

Embedding of fibers in materials has attracted serious attention from researchers and has become a new research trend. Such material structures are usually termed “smart” or more recently “nervous”. Materials can have the capability of sensing and responding to the surrounding environmental stimulus, in the former, and the capability of feeling multiple structural and external stimuli, while feeding information back to a controller for appropriate real-time action, in the latter. In this paper, embeddable fibers, embedding processes, and behavior of fiber-embedded metallic materials are reviewed. Particular emphasis has been given to embedding fiber Bragg grating (FBG) array sensors and piezo wires, because of their high potential to be used in nervous materials for structural health monitoring. Ultrasonic consolidation and laser-based layered manufacturing processes are discussed in detail because of their high potential to integrate fibers without disruption. In addition, current challenges associated with embedding fibers in metallic materials are highlighted and recommendations for future research work are set.

Characteristics comparison of piezoelectric actuators at low electric field: analysis of strain and blocking force

This paper presents measurements and analyses of the strain and blocking forces generated by three different piezoelectric actuators (PXE5, PC5H and Pz28) at low electric field in order to design micro-actuators for nanomotion. The degree of non-linearity and the strain activity are assessed by the introduction of a new parameter with an attempt to relate the capabilities of the actuators to their piezoelectric properties. The blocking forces and the strains were calculated using a finite element method and compared to measurements. The PC5H, a soft type, showed the highest strain and blocking force due to its electromechanical properties.

A NEW ANALYSIS OF WORKSPACE PERFORMANCES AND ORIENTATION CAPABILITY FOR 3-DOF PLANAR MANIPULATORS

A systematic study is performed for the workspace characteristics and orientation capability analysis of 3R planar manipulators. This study will aid the design and control of this kind of manipulators. This particular manipulator is well suited for industrial applications in aided automation manufacturing as well as medical applications for orthopaedic surgery robotics and micro holder for tactile sensing fingers. Based on the characteristics chart method proposed for closed-loop chains in former work (W.Z. Guo, H.J. Zou, B. Han, & Q. Zhang, Mobility of 4R1P-type five-bars using characteristics chart, Proc. ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Salt Lake City, Utah, 2004, 627–634; W.Z. Guo, Q.G. Huang, H.J. Zou et al., Grashof criteria for 4R1P-type five-bar planar parallel mechanisms with active/passive prismatic joint, Chinese Journal of Mechanical Engineering, 41 (8), 2005, 66–73. [in Chinese]), a complete classification and workspace composition are obtained for all the possible 3R planar manipulators. Class I manipulators have one inner circular dexterous regions, while Class II and III manipulators have no inner dexterous regions. If the three-link lengths are not equal to each other at all, the three classes of manipulators have an annular dexterous workspace when the shortest link is serving as the end-effector link. Furthermore, if any two links are the same in length, Class II and III manipulators have no dexterous workspace. By introducing the physical model of the solution space, workspace atlases are produced to show the global performance distributions over the link dimension range in terms of workspace classification, workspace shape, and workspace size. To investigate the joint rotation ranges of the manipulators including orientation capability of the end-effectors, joint space maps are displayed over the characteristics chart by using angled arc at end-effector position which denotes the joint rotation angle range. The study presents a ∗ State Key Laboratory of Mechanical System and Vibration, Institute of Design and Control Engineering for Heavy Equipments, Shanghai Jiao Tong University, Shanghai, 200240, China; e-mail: {wzguo, fengg}@sjtu.edu.cn ∗∗ School of Mechanical, Aerospace, and Civil Engineering, The University of Manchester, P.O. Box 88, Sackville Street, Manchester M60 1QD, UK; e-mail: S.Mekid@manchester.ac.uk Recommended by Prof. A. Alimi (paper no. 206-3226) useful tool to assist synthesis, analysis and motion planning of planar manipulators by describing global performances over the whole design space and the whole reachable workspace.