Multiphase induction motor drives - a technology status review

The area of multiphase variable-speed motor drives in general and multiphase induction motor drives in particular has experienced a substantial growth since the beginning of this century. Research has been conducted worldwide and numerous interesting developments have been reported in the literature. An attempt is made to provide a detailed overview of the current state-of-the-art in this area. The elaborated aspects include advantages of multiphase induction machines, modelling of multiphase induction machines, basic vector control and direct torque control schemes and PWM control of multiphase voltage source inverters. The authors also provide a detailed survey of the control strategies for five-phase and asymmetrical six-phase induction motor drives, as well as an overview of the approaches to the design of fault tolerant strategies for post-fault drive operation, and a discussion of multiphase multi-motor drives with single inverter supply. Experimental results, collected from various multiphase induction motor drive laboratory rigs, are also included to facilitate the understanding of the drive operatio

The 'spinning disk touches stationary disk' problem revisited: an experimental approach

A popular Newtonian mechanics problem, featured in textbooks, physics olympiads and forums alike, concerns two disks with different radii and moment of inertia that rotate differently and that touch each other. Most students struggle to calculate the final angular velocity of the disks, erroneously attempting to use different conservation laws. In this paper we propose a simple experiment that should help physics teachers explain this challenging exercise in an engaging way for the students. By using a smartphone/tablet and video analysis tools, the angular velocity of both disks can easily be tracked as a function of time, clearly showing the three stages of the interaction (before touching, only one disk rotating; touching with slippage; and touching without slippage). Processing and plotting of the data in a spreadsheet immediately shows which quantities are conserved and which are not. Several extensions to the core experiment are also suggested

The Penn Jerboa: A Platform for Exploring Parallel Composition of Templates

We have built a 12DOF, passive-compliant legged, tailed biped actuated by four brushless DC motors. We anticipate that this machine will achieve varied modes of quasistatic and dynamic balance, enabling a broad range of locomotion tasks including sitting, standing, walking, hopping, running, turning, leaping, and more. Achieving this diversity of behavior with a single under-actuated body, requires a correspondingly diverse array of controllers, motivating our interest in compositional techniques that promote mixing and reuse of a relatively few base constituents to achieve a combinatorially growing array of available choices. Here we report on the development of one important example of such a behavioral programming method, the construction of a novel monopedal sagittal plane hopping gait through parallel composition of four decoupled 1DOF base controllers. For this example behavior, the legs are locked in phase and the body is fastened to a boom to restrict motion to the sagittal plane. The platform's locomotion is powered by the hip motor that adjusts leg touchdown angle in flight and balance in stance, along with a tail motor that adjusts body shape in flight and drives energy into the passive leg shank spring during stance. The motor control signals arise from the application in parallel of four simple, completely decoupled 1DOF feedback laws that provably stabilize in isolation four corresponding 1DOF abstract reference plants. Each of these abstract 1DOF closed loop dynamics represents some simple but crucial specific component of the locomotion task at hand. We present a partial proof of correctness for this parallel composition of template reference systems along with data from the physical platform suggesting these templates are anchored as evidenced by the correspondence of their characteristic motions with a suitably transformed image of traces from the physical platform.Comment: Technical Report to Accompany: A. De and D. Koditschek, "Parallel composition of templates for tail-energized planar hopping," in 2015 IEEE International Conference on Robotics and Automation (ICRA), May 2015. v2: Used plain latex article, correct gap radius and specific force/torque number

Application of redundancy in the Saturn 5 guidance and control system

The Saturn launch vehicle's guidance and control system is so complex that the reliability of a simplex system is not adequate to fulfill mission requirements. Thus, to achieve the desired reliability, redundancy encompassing a wide range of types and levels was employed. At one extreme, the lowest level, basic components (resistors, capacitors, relays, etc.) are employed in series, parallel, or quadruplex arrangements to insure continued system operation in the presence of possible failure conditions. At the other extreme, the highest level, complete subsystem duplication is provided so that a backup subsystem can be employed in case the primary system malfunctions. In between these two extremes, many other redundancy schemes and techniques are employed at various levels. Basic redundancy concepts are covered to gain insight into the advantages obtained with various techniques. Points and methods of application of these techniques are included. The theoretical gain in reliability resulting from redundancy is assessed and compared to a simplex system. Problems and limitations encountered in the practical application of redundancy are discussed as well as techniques verifying proper operation of the redundant channels. As background for the redundancy application discussion, a basic description of the guidance and control system is included

Mechatronic development and dynamic control of a 3-DOF parallel manipulator

This is an Author's Accepted Manuscript of an article published in Mechanics Based Design of Structures and Machines: An International Journal, 40:4, 434-452 [September 2012] [copyright Taylor & Francis], available online at: http://www.tandfonline.com/10.1080/15397734.2012.687292The aim of this article is to develop, from the mechatronic point of view, a low-cost parallel manipulator (PM) with 3-degrees of freedom (DOF). The robot has to be able to generate and control one translational motion (heave) and two rotary motions (rolling and pitching). Applications for this kind of parallel manipulator can be found at least in driving-motion simulation and in the biomechanical field. An open control architecture has been developed for this manipulator, which allows implementing and testing different dynamic control schemes for a PM with 3-DOF. Thus, the robot developed can be used as a test bench where control schemes can be tested. In this article, several control schemes are proposed and the tracking control responses are compared. The schemes considered are based on passivity-based control and inverse dynamic control. The control algorithm considers point-to-point control or tracking control. When the controller considers the system dynamics, an identified model has been used. The control schemes have been tested on a virtual robot and on the actual prototype. © 2012 Taylor & Francis Group, LLC.The authors wish to express their gratitude to the Plan Nacional de I+D, Comision Interministerial de Ciencia y Tecnologia (FEDER-CICYT) for the partial financing of this study under the projects DPI2009-13830-C02-01 and DPI2010-20814-C02-(01, 02). This work was also supported in part by the CDCHT-ULA Grant I-1286-11-02-B.Vallés Miquel, M.; Díaz-Rodríguez, M.; Valera Fernández, Á.; Mata Amela, V.; Page Del Pozo, AF. (2012). Mechatronic development and dynamic control of a 3-DOF parallel manipulator. 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IEEE Transactions on Robotics and Automation, 19(3), 403-410. doi:10.1109/tra.2003.810242Clavel , R. ( 1988 ). DELTA, a fast robot with parallel geometry.Proceedings of 18th International Symposium on Industrial Robot.Switzerland: Lausanne, April, pp. 91–100 .Díaz-Rodríguez, M., Mata, V., Farhat, N., & Provenzano, S. (2008). Identifiability of the Dynamic Parameters of a Class of Parallel Robots in the Presence of Measurement Noise and Modeling Discrepancy#. Mechanics Based Design of Structures and Machines, 36(4), 478-498. doi:10.1080/15397730802446501Díaz-Rodríguez, M., Mata, V., Valera, Á., & Page, Á. (2010). A methodology for dynamic parameters identification of 3-DOF parallel robots in terms of relevant parameters. Mechanism and Machine Theory, 45(9), 1337-1356. doi:10.1016/j.mechmachtheory.2010.04.007García de Jalón, J., & Bayo, E. (1994). Kinematic and Dynamic Simulation of Multibody Systems. Mechanical Engineering Series. doi:10.1007/978-1-4612-2600-0Gough , V. E. , Whitehall , S. G. ( 1962 ). Universal tire test machine.Proceedings of 9th International Technical Congress FISITA, London, pp. 117–137 .Sung Kim, H., & Tsai, L.-W. (2003). Kinematic Synthesis of a Spatial 3-RPS Parallel Manipulator. Journal of Mechanical Design, 125(1), 92-97. doi:10.1115/1.1539505Lee, K.-M., & Shah, D. K. (1988). Kinematic analysis of a three-degrees-of-freedom in-parallel actuated manipulator. IEEE Journal on Robotics and Automation, 4(3), 354-360. doi:10.1109/56.796Li, Y., & Xu, Q. (2007). Design and Development of a Medical Parallel Robot for Cardiopulmonary Resuscitation. IEEE/ASME Transactions on Mechatronics, 12(3), 265-273. doi:10.1109/tmech.2007.897257Merlet, J.-P. (2000). Parallel Robots. Solid Mechanics and Its Applications. doi:10.1007/978-94-010-9587-7Merlet , J. P. ( 2002 ). Optimal design for the micro parallel robot MIPS.Proceedings IEEE International Conference on Robotics and Automation, Washington, DC, pp. 1149–1154 .Ortega, R., & Spong, M. W. (1989). Adaptive motion control of rigid robots: A tutorial. Automatica, 25(6), 877-888. doi:10.1016/0005-1098(89)90054-xPaccot, F., Andreff, N., & Martinet, P. (2009). A Review on the Dynamic Control of Parallel Kinematic Machines: Theory and Experiments. The International Journal of Robotics Research, 28(3), 395-416. doi:10.1177/0278364908096236Rosillo, N., Valera, A., Benimeli, F., Mata, V., & Valero, F. (2011). Real‐time solving of dynamic problem in industrial robots. Industrial Robot: An International Journal, 38(2), 119-129. doi:10.1108/01439911111106336Stewart , D. A. ( 1965 ). A platform with 6 degree of freedom.Proceedings of the Institution of Mechanical Engineers.Part 1 15:371–386 .Syrseloudis , C. E. , Emiris , I. Z. ( 2008 ). A parallel robot for ankle rehabilitation-evaluation and its design specifications.Proceeding of 8th IEEE International Conference on BioInformatics and BioEngineering, Athens, October 1–6

Active control of dynamic platforms

The control of a dynamic platform system for offshore operations in adverse weather conditions is discussed in this paper. The aim is to control the deck of the dynamic platform system to remain stationary irrespective of displacement-type base disturbances and force/ torque-type deck disturbances. Two control schemes based on the principle of invariance are described. Open-loop control, with drift cancellation, is implemented for the heave (vertical) motion, which is not always possible to obtain in practical systems. An experimental rig has been used to investigate and validate simulation results. Good simulation and experimental results have been obtained

Time-domain harmonic balance method for aerodynamic and aeroelastic simulations of turbomachinery flows

A time-domain Harmonic Balance method is applied to simulate the blade row interactions and vibrations of state- of-the-art industrial turbomachinery configurations. The present harmonic balance approach is a time-integration scheme that turns a periodic or almost-periodic flow problem into the coupled resolution of several steady computations at different time samples of the period of interest. The coupling is performed by a spectral time-derivative operator that appears as a source term of all the steady problems. These are converged simultaneously making the method parallel in time. In this paper, a non-uniform time sampling is used to improve the robustness and accuracy regardless of the considered frequency set. Blade row interactions are studied within a 3.5-stage high-pressure axial compressor representative of the high-pressure core of modern turbofan engines. Comparisons with reference time-accurate computations show that four frequencies allow a fair match of the compressor performance, with a reduction of the computational time up to a factor 30. Finally, an aeroelastic study is performed for a counter-rotating fan stage, where the rear blade is submitted to a prescribed harmonic vibration along its first torsion mode. The aerodynamic damping is analysed, showing possible flutter

Suspensions of prolate spheroids in Stokes flow. Part 2. Statistically homogeneous dispersions

The simulation method for prolate spheroids in Stokes flow introduced in a companion paper (Claeys & Brady 1993a) is extended to handle statistically homogeneous unbounded dispersions. The convergence difficulties associated with the slow decay of velocity disturbances at zero Reynolds number are overcome by applying O';Brien's renormalization procedure. The Ewald summation technique is employed to accelerate the evaluation of all mobility interactions. As a first application of this new method, the hydrodynamic transport properties of equilibrium hard-ellipsoid structures are calculated for aspect ratios ranging from 3 to 50. Calculated viscosities in the isotropic phase agree reasonably well with published experimental measurements