Showing papers in "Transaction on Control and Mechanical Systems in 2013"

Structural and Contact Analysis of Disc Brake Assembly During Single Stop Braking Event

Abstract: An automobile disc brake system is used to perform three basic functions, i.e. to reduce speed of a vehicle, to maintain its speed when travelling downhill and to completely stop the vehicle. During these braking events, the disc brake may suffer of structural and wear issues. It is quite sometimes that the disc brake components fail structurally and/or having severe wear on the pad. Thus, this paper aims to examine stress concentration, structural deformation and contact pressure of brake disc and pads during single braking stop event by employing commercial finite element software, ANSYS. The paper also highlights the effects of using a fixed calliper, different friction coefficients and different speeds of the disc on the stress concentration, structural deformation and contact pressure of brake disc and pads, respectively.

Utilization of Whale-Inspired Tubercles as a Control Technique to Improve Airfoil Performance

Abstract: This research exploits the Whale-inspired tubercles as a control technique to improve the performance of airfoils. The flow field of NACA0012 airfoil with spherical leading-edge tubercles was computationally simulated. This airfoil section resembles the flipper of the Humpback whale and is used in many engineering applications. Tubercles, with a diameter of 10% of the airfoil chord (C), are arranged such that the span-wise distance between the centerlines of two adjacent tubercles is 20% C. k- turbulence model was used for a wide range of angle of attack (α = 0 o - 25 o ) and Reynolds number (Re = 65,000 - 1,000,000). Results demonstrated that the presence of tubercles improves the airfoil performance by delaying or even preventing stall in the investigated range of operating conditions (α and Re). Simple active control scheme is proposed to obtain optimum performance (i.e., optimum values of lift and drag coefficients).

Data–driven Modelling of a Wind Turbine Benchmark for Fault Diagnosis Application

Abstract: In order to improve reliability and safety of wind turbines, it is important to detect and isolate faults as fast as possible, and handle them in an optimal way. This work describes a data–driven modelling approach oriented to the design of a diagnosis scheme, used to detect faults, and isolate them as early as possible, in order to avoid possible catastrophic consequences. A hybrid modelling approach is used here since the model under investigation is nonlinear, whilst the wind speed measurement is uncertain since it is influenced by the turbulence around the rotor plane. The modelling method relies on piecewise affine prototypes, which are identified from the noisy measurements acquired from the simulated wind turbine. The fault detection and isolation strategy is thus designed based on these hybrid models. The wind turbine simulator is finally used to validate the achieved performances of the suggested fault diagnosis scheme.

CFD Simulation of Fuselage Aerodynamics of the "ANSAT" Helicopter Protype

Abstract: This paper investigates the aerodynamic lift and drag of the ANSAT helicopter fuselage prototypes using Computational Fluid Dynamics. The CAD model of the fuselage was meshed using an unstructured grid and computed using a viscous flow model under the assumption of steady flow conditions. To account for the influence of the helicopter rotor an actuator disk model was used and the results were compared with computations for the isolated fuselage. The contributions to the total drag of the individual helicopter fuselage components were also studied using different turbulence models. The key components of the fuselage drag were identified.

A comparison between integer order and fractional order controllers applied to a hydro-electromechanical system

Abstract: The purpose of this paper is to compare the behaviors of two types of controllers: a traditional controller, represented by a PID controller, and two fractional order controllers, represented by a generalized PI l D m and a CRONE controllers. These three controllers are applied to a hydro-electromechanical test bench based on a double-direction pump, a uniform tank and a level sensor. In order to design the three controllers, an uncertain linearized model of the test bench is established using the grey-box approach. Then, a synthesis method for each controller, in frequency domain, is developed. In accordance with the user specifications and in order to do a significant comparison, the three control systems have the same behavior for the nominal operational point. Finally, a sensitivity analysis is made to observe the robustness of each control system. The obtained results show that the CRONE control system is more robust than the other control systems.

Dry Sliding Studies of Porosity on Sintered Cu-based Brake Materials

Abstract: Cu-based composites with its promising engineering application due to their excellent thermophysical properties coupled with better high temperature mechanical properties as compared to pure copper and copper alloys. An investigation on a Cu-based composite frictional material re-inforced with other elements for train brake was treated under P/M route for its wear behavior in terms of sintering temperature and porosity. The dry sliding wear characteristics investigation test with a high pressure pad-on-disc tester was developed for the three different sintering temperatures samples. The optimal porosity was obtained at the highest sintering temperature of 950 o C. That same optimal porosity gave the lowest wear frictional coefficient, and the highest coefficient of friction. Three forms of wear mechanisms were observed during the dry sliding process, namely, delamination wear, plowing wear and abrasive wear. High wear rates were found on samples sintered at 850 o C and 900 o C. Abrasive wear and the delamination wear were the main cause of high wear coefficient, low wear number and low coefficient of friction. The nature of abrasive surfaces observed were classified into three divisions, namely, smooth abrasive surfaces; rough abrasive surface; and the highly abrasive surface. The dominance of wear is discussed in the light of SEM photography of the worn surfaces.

MRAS for Speed Sensorless Direct Torque Control of a PMSM Drive Based on PI Fuzzy Logic and Stator Resistance Estimator

Abstract: In this paper, a sensorless Direct Torque control (DTC) for Permanent Magnet Synchronous Motor (PMSM) drive based on Adaptive Model Reference (MRAS) algorithm and PI with adapted gains fuzzy logic (FL) are presented. The MRAS is utilized to estimate speed and stator resistance and compensate the effects of parameter variation on (stator resistance variation introduce errors flux and torque estimation and affect the performance of DTC). In other hand, speed regulation by PI with two adaptive FLC is investigated and compared with classical PI controller. Simulation results are presented and show the effectiveness of the proposed method.

Bridging Cell Multiscale Modeling of Nanoindentation at Finite Temperature

Abstract: This paper presents the simulation of nanoindentation in copper thin film using a multiscale finite element framework for modeling coupled continuum/atomistic systems at finite temperature. Seamless coupling between the atomistic and continuum domains is performed through bridging cells where the underlying atoms define the constitutive formulation for the cells with an overlapping local energy contribution accounting for the missing atomic interactions at the continuum/atomistic interface. The method implements a temperature dependent potential for finite temperature simulations avoiding the use of small timesteps. The results from the nanoindentation simulation are compared to a fully molecular dynamics simulation with respect to indenter load vs. displacement for various temperatures. Differences between multiscale and fully atomistic simulations were very small with the use of the multiscale modeling resulting in a significant reduction in simulation time showing the accuracy of the temperature dependent potential and proposed coupling scheme.

A Practical Methodology for Cellular Manufacturing Systems Design – an Industrial Study

Abstract: The product oriented organization of manufacturing systems based on group technology cells, typical of lean production, is a very effective organization to timely meet customer requirements and take full advantage of production resources. Frequently it has been pointed out that studies on cellular manufacturing systems tend to be theoretical and addressing only a few of the relevant practical issues. In this paper, a comprehensive industrial study for reconfiguring a production system into a product oriented manufacturing system, based on GT cells, carried out in a company manufacturing leather goods, it is reported. This study take into account all important and necessary issues, for system reconfiguration, namely capacity requirements, actual and expected future demand, existing resources and required and available physical space. A practical methodological approach for part family formation, machines allocation to cells and cellular layout planning are put forward. Procedures for dealing with exceptional elements towards minimizing intercellular workflow and for streamlining material flow within cells and across cells are also described and implemented. In this particular study separating kits of raw parts at the beginning of parts processing and joined them together again at the end of processing was a requirement that needed to be addressed and made reliable to avoid severe mistakes when assembling parts into final products. This requirement was an additional motivation for organizing production into cells leading to a much more reliable kitting operation greatly due to the streamlined and synchronized work flow of parts achieved. The study proposes reorganizing the system into three autonomous GT cells and a gateway work centre, with resources practically reduced to the minimum required based on product demand. The study compares the initial configuration solution with the proposed one showing advantages of the proposed solution under a few evaluation issues, namely in relation to work flow organization, movement of materials and reliability of the parts kitting for final assembly.

Actuation Technologies for Humanoid Robots with Facial Expressions(HRwFE)

Abstract: Actuators are key components for creating Humanoid Robots with Facial Expressions (HRwFE). HRwFE are those robots capable of demonstrating expressions utilizing artificial muscles, deformable skin, motion control systems and artificial intelligence. The main objective of this paper is to briefly assess various actuation technologies: electromagnetic, pneumatic piezoelectric, shape memory alloy, conducting polymer actuators in terms of various performance indices and comparing the properties with muscles in human head. Research in HRwFE are getting momentum and there exist a strong derive to build them because they can potentially be used for various applications including health care, military, industry, and household. For all kinds of humanoid robots, the selection or synthesis of actuators that meet the need of biological head is challenging. This paper focuses on the issues mentioned above and presents comparative assessment of the actuation technologies focusing on humanoid head.

Thermomechanical Analysis of a Disc Braking System

Abstract: The main purpose of this study is to analysis the thermomechanical behavior of the dry contact between the brake disc and pads during the braking phase. The simulation strategy is based on computer code ANSYS11. The modeling of transient temperature in the disk is actually used to identify the factor of geometric design of the disk to install the ventilation system in vehicles. The thermal-structural analysis is then used to determine the deformation established and the Von Mises stresses in the disk, the contact pressure distribution in pads. The results are satisfactory compared to those found in the literature

New automatic control solutions for the drilling industry

Abstract: The goal of this paper is to address automatic control challenges within drilling for the oil and gas industry. The potential for automatic control is great for the drilling industry. Heavy machinery is used to handle pipes and other equipment topside and in and out of the hole. These machines can be controlled remotely with a joystick. Very advanced tools are being used downhole several km away from the rig and these are often controlled remotely. Mud pulse telemetry with low bandwidth is used to communicate with downhole equipment. Drilling involves certain risks and mistakes may have disastrous consequences both for people and economically, e.g. a blow-out. Safety is therefore always the most important issue, and new solutions must be robust and fault tolerant. Extensive testing is required before being used in an actual drilling operation. Managed pressure drilling is a relative new method for drilling challenging wells with narrow margins requiring precise pressure control. Nonlinear model based control solutions and observers have been developed for this technology. This is addressed in this paper together with experimental results. In addition an overview of some other interesting challenges is given.

Numerical Assessments of Impingement Flow over Flat Surface due to Single and Twin Circular Long Water Jets

Abstract: Hydrodynamics of impingement flow is a key partner of heat transfer analysis of run-out table (ROT) steel cooling. Velocity and pressure profiles before and after impingement of long circular free-surface industrial water jets (Re = 16,669-50,068) was numerically studied and also wetting front propagation and size of impingement zone were computed. The turbulent models represented impingement water flows over surface better in good agreement with the experimental data at the ROT facility. Higher velocity gradient was obtained for long turbulent jets indicating enhanced heat transfer at impingement zone. The effect of local pressure on saturation temperature changes predication of boiling heat transfer correlations up to 9% which is noticeable for ROT cooling. Impingement zone was found smaller respect to the estimation used in ROT modeling obtained from short jets experiments. For twin jets, simulation show calm interaction of low flow rate water jets with no splashing in accordance with the experiment. Water film thickness in interaction zone is elevated toward jet-jet axis.

Fuzzy Control of Piezoelectric Stewart Platform for Active Vibration Control Purpose

Abstract: This paper presents a simulation study aimed at investigating the potential of using fuzzy controller for active vibration control in a piezoelectric Stewart platform. The focus of the study is to assess, through simulation, the control authority of the piezo stack actuators for effectively controlling the Stewart platform vibration. Dynamic analysis of the structure is performed using Matlab/Simulink. Each leg of the active interface consists of a linear piezo stack actuator, a collocated velocity sensor and flexible tips for the connections with the two end plates. The piezoelectric stack is modeled as a bar element and the electro-mechanical coupling property is simulated. The open loop and closed loop dynamic response simulations are done in Matlab/Simulink. The closed loop implementation is aimed at achieving maximum damping of the six rigid body modes of the system, through six local fuzzy velocity feedback controllers. Simulations are carried out to characterize the effect of control on the overall response of the closed loop control to white noise disturbance forces, with the constraint on the stack actuator voltage to be within a specified bound. Using fuzzy controller shows improvement in the damping of the structure.

Bicycle Simulator with Cylindrical Magnetorheological Fluid Brake

Abstract: Cycling is a healthy and moderate aerobic exercise for the elderly and it works well not only to their physical functions but also to their mentalities. In order for the exercise machine that can facilitate the moderate aerobic exercise for users who cannot do real cycling, we have developed the virtual reality bike (VR Bike) with a cylindrical MR fluid brake. In this paper, system integration of the VR Bike and control of its pedal resistance based on the virtual reality environment are described. We developed a pedal torque controller with a PIC microcomputer, and a visual controller with a PC. These controllers were integrated and connected each other. Validation tests were conducted to evaluate the validity of the system. According to the results, the developed controller adequately performed pedal torques on the basis of the conditions (with / without air resistance and rolling friction, on flat / slope road) of the bike in the virtual world.

Influence of Roughness and Friction Coefficient on the Contact Wear in Partial Slip Conditions

Abstract: Based on a numerical model to investigate wear for smooth and rough contacting bodies under partial slip conditions, the paper presents the main influences of the roughness and coefficient of friction on this phenomenon. The wear simulation is based on the Archard’s wear law and is applied to a sphere on flat geometry. The influence of roughness, even for small magnitudes, is an important factor that cannot be neglected. A comparison between influence of a constant coefficient of friction and a variable one in the slip area is also presented. The material is considered as being deformed elastically and no plastic effect is considered.

Micro Languages for Systems

Abstract: Systems are generally described by using many various languages for their specification, realization, implementation, etc. In this context, the paper explains how generic datatypes and higher-order functions can be used to model languages and to pass more easily and formally from one language to another. As an application the paper present a (meta)model for temporal properties, states-transitions models, and implementation, and the transformations between them.

Heat Transfer Performance of Loop Thermosyphon using Enhanced Boiling and Condensation Surfaces

Abstract: We have developed a loop thermosyphon to provide high cooling performance for cooling electronic devices. The loop thermosyphon used a porous structure on a boiling surface and a microgroove structure on a condensation surface. In this study, we measured the heat transfer performance and we obtained the following results. The evaporation heat transfer of the porous structure is about six times as large as that of the flat surface. The total thermal resistance of the thermosyphon using a porous structure on the boiling surface and a microgroove structure on the condensation surface is about half of that using flat surfaces.

Performance Decay Simulation of a Gas Turbine for Helicopter Propulsion

Abstract: The effects of turbines blades erosion on the performance of a twin shafts gas turbine engine for helicopter propulsion are investigated by simulation. The engine behavior has been simulated by amathematical model extensively validated. In order to understand the effects of low (LPT) and high (HPT) pressure turbine stator erosion (increase of throat section and blade thickness reduction according to the experimental evidence from the engine tests from Piaggio Aero Industries), the LPT and HPT performance have been simulated and their performance maps have been obtained with a high level of accuracy. Nine degradation levels have been considered. The introduction of the modified turbine characteristics into the gas turbine simulator has allowed to estimate the degradation effects on the overall engine performance, both in constant fuel mass flow rate (engine on the test bed), and engine running under effective operative conditions (engine installed on the helicopter) with the addition of the fuel control module into the simulator.

Measurement and Evaluation System for Self-Training System of Bed-Making Activity

Abstract: This paper aims to construct a nursing self-training system of bed-making in which nurses must perform some skills for handling equipment (a bed, a bed pad, and a sheet) and for avoiding bodily injury. Eight evaluation points of the bed-making task, related to trainees’ posture and states of equipment, were identified through nursing textbooks and discussed with nursing teachers. To recognize and evaluate the points by image processing, we developed a system using three RGB-D (RGB color and depth) sensors. To increase the recognition rate, we clustered the color information by the K-means clustering method and then divided the bed-making procedure into three segments using color and depth information of the whole images. The average accuracy achieved by the proposed system in the evaluation experiment where 15 trainees participated was 80 %, an average consistent with that achieved by a human nursing teacher.

Fabrication of Nano-periodic Structure on Plastic Film for Water Repellent Using Femtosecond Laser

Abstract: The lotus has been a symbol of extreme water-repellent (superhydrophobicity) characterized by a high contact angle and low sliding angle. We demonstrate a methodology to fabricate a three-dimensional (3-D) nano-periodic structure on a thin plastic film in an attempt to process a superhydrophobic surface. The whole fabrication process was carried out in two steps:(i) writing a nano-periodic 3-D pattern on a metal (mold) surface by focused femtosecond (fs) laser pulses and (ii) transferring the 3-D pattern from the mold to a plastic film by hot embossing. This technique allows the fabrication of nano-periodic structures as small as 800 nm in pitch. The contact angles were improved on both the surfaces of the metal mold and the plastic film.

Manipulation of Biological Cells Using a Nano-Micronewton Force Controlled Gripper

Abstract: Nano-micro grippers are able to pick-transport-place the micro or nanometer –sized materials, such as manipulation of biological cells or DNA molecules in a liquid medium. This paper proposes a novel monolithic nano-micro gripper structure with two axis piezoresistive force sensor which its resolution is under nanoNewton. The results of the study have been obtained by the simulation of the proposed gripper structure in Matlab software. Motion of the gripper arm is produced by a voice coil actuator. The behavior of the cell has been derived using the assumptions in the literatures. Moreover, two simple PID controllers, one for control of the gripper motion and another for control of the force during manipulation of a biologic cell, have been implemented. Although the proposed gripper has not been fabricated, since the geometrical dimensions of the proposed gripper is the same as previously developed electrothermally actuated micro-nano gripper, the results of force control have been also compared with it. The simulated results with the very simple PID force controller which has a more rapid response than previously developed electrothermally actuated micro-nano gripper show that the designed gripper has the potential to be considered and fabricated for manipulation of biological cells in the future.

Integrating Multi-Sensors for Observing Post ACL Reconstruction Recovery Progress

Abstract: This study investigates the integration of wireless micro-electro-mechanical-systems (MEMS) and electromyography (EMG) sensors for developing a motion analysis system for post-operative recovery monitoring of Anterior Cruciate Ligament (ACL) reconstructed subjects based on biofeedback mechanism. The kinematics and neuromuscular signals have been combined using mixed signal processing techniques and a feature set has been generated for classification of recovery status of subjects. Two intelligent techniques (Feed-forward Artificial Neural Network and Fuzzy Rule-based Classifier) have been tested and compared for providing rehabilitation status of the subjects. The system has been tested on a group of national athletes and it provides an un-obstructive assessment of the kinematics and neuromuscular changes occurring after ACL reconstruction in an athlete. The successful implementation and testing of multimodal sensors' integration show its feasibility in identifying the clinical stage of the recovery process of athletes after ACL repair and using it as an assistive tool for clinical decision-making during the rehabilitation regimen.

3D Sensing and Mapping by a Tracked Mobile Robot using a Movable Laser Ranger Finder

Abstract: This paper presents 3D sensing and mapping method for a mobile robot that is equipped with an arm-type sensor movable unit and a laser range finder (LRF). The arm-type sensor movable unit is mounted on the robot and the LRF is installed at the end to change its position. Changing the height of the sensor by keeping flat is also possible for the system. It may be difficult for moving robot to apply mapping algorithms such as the iterative closest point (ICP) because sets of the 2D data at each sensor height may be distant in a common surface. This paper proposes a method for this kind of sensing by using an interpolation. Dynamic programming was applied to compute corresponding sensing points for the ICP. Several experimental results provide validity of proposed methods.

Experimental Measurement of Viscosity of Boron Nitride-Polyalpha Olefin Nanofluid

Abstract: : A new nanofluid of boron nitride (BN) nanoparticles dispersed in polyalpha-olefin oil (PAO) base fluid has been developed and its rheological behavior has been studied experimentally. Nanofluids of volumetric concentrations 0.25%, 6% and 1% in PAO base fluid were tested. It was found that the nanofluid behaved as newtonian fluid for the tested temperature range from -20°C to 70°C. The experimental results showed that the viscosity increases with an increase in concentration and decreases with increase in temperature. New correlations were developed expressing the viscosity as a function of nanoparticle concentration and nanofluid temperature.

A Survey on the Application of Control and Mechanical Systems for Human Motor Learning and Recovery

Abstract: Rehabilitation engineering is a strong emerging field in control and mechanical systems that provides technological solutions to disabled individuals. One branch of rehabilitation engineering is the application of control systems and robotic technology for human motor recovery. This paper outlines the recent developments in rehabilitation robotic research and related control systems. The available techniques are discussed in the context of upper limb rehabilitation and lower limb / gait rehabilitation. The control systems technology utilized in rehabilitation robotics is discussed in three versions of complexity. The potential benefits of each version are outlined with the different improvements seen in the progression of technology. The conclusion of this paper identifies the outcomes and challenges faced in this area of research.

Analysis of an Estimate of The Region of Attraction of an IDA-PBC Control of a Ball and Beam Underactuated Mechanism

Abstract: The ball and beam machanism belongs to the class of underactuated mechanical systems. Recently, several control design techniques have been proposed to control underactuated systems. The Interconnection and Damping Assignment (IDA) — a formulation of Passivity – Based Control (PBC) — is one of these control design tools. The IDA-PBC technique applied to the stabilization of a ball and beam mechanism has been recently reported. The contribution of this paper is a novel analysis to obtain an estimate of the region of attraction of the IDA-PBC control of a ball and beam mechanism that resolves the practical motivated formulation of ensuring simultaneously that the beam evolves within upward configurations and the ball remains in the beam. Numerical simulations illustrate these results.

Vibration analysis of a rotating axially non-homogeneous magnetorheological fluid sandwich beam

Abstract: Vibration responses of a rotating multi-layer beam structure comprising axially homogeneous and non-homogeneous magneto-rheological (MR) fluids layer are investigated. The governing equation of motion of a rotating multi-layer MR beam is formulated in finite element form. The validity of the proposed finite element formulation is demonstrated by comparing the simulation results with those obtained from Ritz method. Simulations are performed to investigate the influences of the rotational speed and the hub radius on the natural frequencies, the loss factor and the mode shapes of the non- homogeneous MR fluid sandwich beam. It is concluded through various parametric studies that in addition to the applied magnetic field, the rotational speed of the MR fluid sandwich beam and the hub radius significantly affects the variation in natural frequencies and the loss factor of the MR adaptive beam. It is also concluded that the application of non-homogeneous MR fluids could also alter the deflection pattern of the beam, particularly the location of the peak deflection.

Development of a Bilateral Support System with Force Input Deflecting Construction

Abstract: Finishing processes are performed by workers on a piece-by-piece basis. Accordingly, the accuracy of the product depends on the worker's skill. The aim of this research is to develop a machining support system via bilateral control system which accepts various machining theories and reflects the operation force into the machining geometry. Here, we propose a new bilateral controller for machining support which has an original component, FID coefficient for changing the connecting force between master and slave robot dynamically. The effectiveness of this system is shown in simulations and experimental result with press motion.

Realization of an E-field Sensory System for Sensor Based M/M Cooperation

Abstract: In this paper we describe the realization of a proximity and contact sensor which exploits E-field measurements. E-field sensors of that kind can be profitably employed to equip industrial manipulators for detecting proximity and contact with obstacles. Such feature allows the realization of work-cells where man and robot share safely the same workspace and cooperate by exchanging basic information. In facts, by interpreting the sensory signal with the aid of additional information about the robot’s motion, unintentional proximity or unintentional contact between man and robot can be distinguished from intentional contact. In the first situation, the robot motion can be stopped to avoid damages, while, in the second situation, intentional contact can be used to transmit suitable commands. After describing the sensor architecture and characteristics, an experimental prototypal installation on an industrial manipulator is described and the results of various tests are illustrated.