Transactions of the Canadian Society for Mechanical Engineering

Volume 34 (2010), Issue 1

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In this paper, an algorithm for the inertial sensors errors reduction in a strap-down inertial navigation system, using several miniaturized inertial sensors for each axis of the vehicle frame, is conceived. The algorithm is based on the idea of the maximum ratio-combined telecommunications method. We consider that it would be much more advantageous to set a high number of miniaturized sensors on each input axis of the strap-down inertial system instead of a single one, more accurate but expensive and with larger dimensions. Moreover, a redundant system, which would isolate any of the sensors in case of its malfunctioning, is obtained. In order to test the algorithm, Simulink code is used for algorithm and for the acceleration inertial sensors modeling. The Simulink resulted sensors models include their real errors, based on the data sheets parameters, and were conceived based on the IEEE analytical standardized accelerometers model. An integration algorithm is obtained, in which the signal noise power delivered to the navigation processor, is reduced, proportionally with the number of the integrated sensors. At the same time, the bias of the resulted signal is reduced, and provides a high redundancy degree for the strap-down inertial navigation system at a lower cost than at the cost of more accurate and expensive sensors.

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Because of the necessity of maintenance and operation in industries in which the equipment layout is occasionally tight, the space for a muffler is constrained. An interest in maximizing the acoustical performance of mufflers within a limited space is of paramount importance. As mufflers hybridized with reverse-flow ducts may visibly increase acoustical performance, the main purpose of this paper is to numerically analyze and maximize their acoustical performance within a limited space. In this paper, a four-pole system matrix for evaluating the acoustic performance — sound transmission loss (STL) — is derived by using a decoupled numerical method. Moreover, simulated annealing (SA), a robust scheme used to search for the global optimum by imitating the metal annealing process, has been used during the optimization process. Before dealing with a broadband noise, the STL’s maximization with respect to a onetone noise (300 Hz) is introduced for a reliability check on the SA method. Moreover, an accuracy check of the mathematical model is performed. Results reveal that the STL of a muffler with reverse-flow perforated ducts can be maximized at the desired frequency for pure tone elimination; moreover, the noise reduction for a broadband noise can reach 97.5 dB. Consequently, the approach used for the optimal design of the mufflers is simple and effective.

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The library of symbolic C++ routines is broadly used throughout the world. In this article, we consider its application in the symbolic treatment of rigid multibody systems through a new software KINDA (KINematic & Dynamic Analysis). Besides the attraction which represents the symbolic approach and the effectiveness of this algorithm, the capacities of algebraical manipulations of symbolic routines are exploited to produce concise and legible differential equations of motion for reduced size mechanisms. These equations also constitute a powerful tool for the validation of symbolic generation algorithms other than by comparing results provided by numerical methods. The appeal in the software KINDA resides in the capability to generate the differential equations of motion from the choice of the multibody formalism adopted by the analyst.

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Six-degree-of-freedom instrumented spatial linkages are often used to measure anatomical joint motion for clinical studies or research applications in biomechanics. Their appropriate design is a fundamental issue to allow for accurate measurements and ease of application, and this mainly relies on addressing the kinematic analysis of the linkage. The aim of this paper is to integrate and extend past literature in the field by giving a generalized set of guidelines and ready-to-use mathematical relationships to approach the whole kinematic analysis of a general instrumented spatial linkage in a systematic way. The direct kinematics is formulated using common robotics formulation and, with reference to a specific linkage architecture, a geometrical approach is proposed to solve for the inverse kinematics in closed-form. Kinematic error analysis is addressed in a generalized way by using differential transformation theory, and it is then applied to the specific case under study. By the proper definition of a virtual joint, the inverse kinematics is used to estimate the static performance of the linkage over its specific task space.

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Tensegrity mechanisms are slowly emerging as potential alternatives to more conventional mechanisms for certain types of applications where a reduced inertia of the mobile parts and a high payload to weight ratio are sought. With this in mind, a two-degree-of-freedom planar tensegrity mechanism is developed using a simple actuation strategy to keep the mechanism in self-stressed configurations. Solutions to the mechanism’s direct and inverse kinematic problems are first developed and are then used to determine analytical expressions for its workspace boundaries.

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In this study, it was aimed to investigate the effect of ceramic coating on a turbocharged diesel engine performance and energy balance. For this purpose, cylinder head, valves and pistons of the engine were coated with yttria stabilized zirconia layer with a thickness of 0.35 mm nickel-chromiumaluminium bond coat, as well as the atmospheric plasma spray coating method with a thickness of 0.15 mm. Then, the engines were tested for full load. The heating values of the diesel fuel and ethanol were 46.2 and 25.182 MJ/kg, respectively. Because of the lower heating values of the ethanol, compared with the diesel fuel, it appears to have lower following to engine power, torque and SFC. Compare to engine power of SDE, LHRe has increased about 2%, LHReth has decreased about 22% at all engine speed. Compare to engine torque of SDE, LHRe has increased about 2.5%, LHReth has decreased about 23% at all engine speeds. Compare to SFC of SDE, LHRe has decreased about 1.1%, LHReth has increased about 54% at all engine speeds. Compare to exhaust turbine inlet temperature of SDE, LHRe has increased about 15%, LHReth has decreased about 17% at all engine speeds.

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The singularities for a class of kinematically simple 7-jointed revolute manipulators are found. Within the class, unnecessary lengths and 4-jointed spherical groups of joints are avoided, and successive joints are perpendicular or parallel. Four different joint layouts are required to complete this class. The concept of screw reciprocity is used to find the singular (velocity-degenerate) configurations. Reciprocal screw quantities characterizing the lost instantaneous motions are derived.

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This study focuses on the optimum design of the damped dynamic vibration absorber (DVA) for damped primary systems. Different from the conventional way, the DVA damper is connected between the absorber mass and the ground. Two numerical approaches are employed. The first approach solves a set of nonlinear equations established by the Chebyshev’s equioscillation theorem. The second approach minimizes a compound objective subject to a set of the constraints. First the two methods are applied to classical systems and the results are compared with those from the analytical solutions. Then the modified Chebyshev’s equioscillation theorem method is applied to find the optimum damped DVAs for the damped primary system. Various results are obtained and analyzed.

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This paper presents the design and implementation of a systematic fuzzy modelling methodology for the inverse dynamic modelling of robot manipulators. The fuzzy logic modelling methodology is motivated in part by the difficulties encountered in the modelling of complex nonlinear uncertain systems, and by the objective of developing an efficient dynamic model for the real-time model-based control. The methodology is applied to build the fuzzy logic-based inverse dynamic model of a prototyped wire-actuated parallel manipulator with uncertain dynamics. The developed inverse dynamics has been used in a fuzzy model-based adaptive robust controller for the tracking control of the parallel manipulator.

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This paper presents an approach for synthesizing all possible mechanism systems of kinematic building blocks in a mechanism concept library. The kinematic building blocks are defined as SISO primitive mechanisms, and their serial and/or parallel combinations are expressed as corresponding out-trees based on graph representation. By representing the constructive building blocks as labeled vertices and their possible combination relationships as directed edges, the synthesis approach is developed by adopting graph enumeration theorem. An illustrative example of four kinematic building blocks, including two crank-rocker linkages and two slider-crank mechanisms, is provided to validate the presented approach. The result shows that all feasible mechanism systems can be obtained effectively by following the synthesis method and which provides more alternatives in the library during design or re-design of mechanisms.