Transactions of the Canadian Society for Mechanical Engineering
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Volume 37 (2013), Issue 2
Design for optimal performance of 3-RPS parallel manipulator using evolutionary algorithms
Sabbavarapu Ramana Babu, Vegesina Ramachandra Raju, Koona Ramji
This paper presents an optimal kinematic design for a general type of 3-RPS spatial parallel manipulator based on multi-objective optimization. The objective functions considered are Global Conditioning Index (GCI), Global stiffness Index (GSI) and Workspace volume. The objective functions are optimized simultaneously to improve the dexterity as well as the workspace volume which represents the working capacity of a parallel manipulator. A multi-objective Evolutionary Algorithm based on the control elitist non-dominated sorting genetic algorithm is adopted to find the true optimal Pareto front. A constraint Jacobian matrix is derived analytically and the manipulator workspace is generated by numerical search method. The static analysis of the manipulator is also carried out to determine the compliance of the end-effecter.
Motion planning for 6-DOF assembly part positioning and alignment adjustment
Jun Hong, Shao F. Wang, Emenike Chukwuma, Jing H. Zhang, Zhi G. Liu
In this paper, a 4-PPPS redundantly actuated parallel mechanism and its motion planning method are proposed. The mechanism can be applied to the positioning and alignment of large subassembly in engineering assembly. The optimization of the positioning and alignment trajectory is performed with the minimum energy consumption as the objective function. The system test data shows that the assembly platform and the motion planning method can satisfy the requirements of accuracy, efficiency and stability of the positioning and alignment operations.
Design of a sonic drill based on virtual prototype technology
Yu Wang, Baolin Liu, Qin Zhou, Yuanbiao Hu, Guomin Li
Sonic drilling is a novel sampling technology applied in many fields. Based on SolidWorks software, a dynamics virtual prototyping is utilized to develop a physical sonic driller by demonstrating collision detection and optimizing overall layout and key component structures. Key hydraulic and structural parameters are optimized using a mathematical model. Search for the optimized parameters and operating conditions for this multi-body mechanical system is conducted experimentally. The practical results show that the virtual prototype technology not only shortens the design cycle but also improves the quality of the conventional design. The new sonic driller designed by this method is both environmentally friendly and smarter.
Optimum synthesis of path generating adjustable mechanisms with improved slope continuity of the control parameter
Hrishikesh Y. Raste, Ameya P. Apte, Gunesh R. Gogate
Adjustable mechanisms have been studied in literature for path and function generation. In this paper, a path generating four-bar mechanism with an alternate single parameter adjustment is proposed and optimally synthesized, using the method of Differential Evolution. Two new approaches are developed, aimed at improving the slope continuity characteristic of the control parameter. Optimum synthesis results are obtained using the proposed approaches. The results show that the proposed approaches lead to improved slope continuity characteristics of the control parameter.
Workspace of wire-actuated parallel manipulators and variations in design parameters
Vahid Nazari, Leila Notash
The purpose of the paper is to investigate the effect of small variations (uncertainties) and large variations in design parameters on the size and shape of the workspace of the wire-actuated parallel manipulators. The static force/moment balance equations, taking into account the null space of the Jacobian matrix, are used for the workspace analysis. The parameters examined include: the winding direction of wires on the pulleys; the radius of the pulley; the orientation, radius, and mass of the mobile platform; the peg length; and the ratio of the peg radii at the entrance and exit. Also, the effect of the geometric arrangement of wire attachment points and the number of wire connection points on the mobile platform, on the size and shape of the workspace is considered. The simulation results show the effect of small and large variations in the aforementioned parameters on the workspace of wire-actuated parallel manipulators without and with gravity.
Application of the Taguchi quality method to design navigation constants that are robust to target maneuvers
Chien-Chun Kung, Feng-Lung Chiang, Ciann-Dong Yang
The object of this paper is to present a quality control approach to design the navigation constants for missile guidance law that are robust for targetís maneuverability and missileís performance. Targetís maneuvers and missile's time constants are considered to be noise factors and Taguchi Quality Method (TQM) is used to conduct matrix experiments and determine the robust navigation constants. From the simulation results for three kinds of guidance laws, we find that robust navigation constants have a greater ability to enhance the interception of targets that are performing uncertain maneuvers with less interception time and smaller miss distances in the hitting phase.
Numerical and experimental investigations of EGR distribution in a di turbocharged diesel engine
Reza Rahimi, S. Jafarmadar, S. Khalilarya, A. Mohebbi
This paper presents the results of numerical and experimental investigations to evaluate the distribution of exhaust gas recirculation (EGR) between cylinders in a DI turbocharged diesel engine. The turbulent three-dimensional flow field was analyzed by the numerical solution of conservation equations with an appropriate turbulence model. EGR was applied to intake manifold with various rates at cooled and non-cooled states. The experiments were conducted on an MT4.244 turbocharged DI diesel engine under full load condition at 1900rpm. The model was validated by experimental data with a good agreement between experimental measurements and numerical predictions. Using this method, it is possible to control EGR distribution so as to reduce emissions formation as well as to improve performance.
Structural synthesis of ancient Chinese original crossbow
The original crossbow was one of the most important weapons in ancient China. Since crossbows have diversified types and were widely used in ancient China after the Spring and Autumn Period (770-476 BC), the original crossbow should have many designs in different eras and regions. The aim of this work is to synthesize mechanism structures of the original crossbow. Based on the analyses of crossbows, the structural characteristics and design constraints of this device are concluded. Then, according to the concepts of generalization and specialization subject to the concluded design constraints, twelve feasible structures of mechanism that meet the technological standards of the subjectís time period are reconstructed.
Full journal title: Transactions of the Canadian Society for Mechanical Engineering
Abreviated journal title: Trans. Can. Soc. Mech. Eng.
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