Optimum Synthesis and Design of a Hood Linkage for Static Balancing in One-Step

The conventional approach of the mechanism design process, generally, has a two-step procedure: Kinematic synthesis/analysis of the mechanism in the first step and optimization of the synthesized/analyzed mechanism based on optimization criteria in the second step. This study presents an approach that combines kinematic synthesis with the static balancing of the same, and optimization, into a one-step procedure. As an example of this one-step design process, a tension-spring assisted four-bar hood linkage optimal synthesis and design is performed in one-step. This one-step solution includes kinematic synthesis and analysis of the hood linkage, virtual work, static balancing with tension spring, and optimization in the presence of joint friction. The resulting design requires a minimum force to raise and lower the hood in the presence of unknown optimum levels of joint friction while the hood is statically balanced for its entire range of motion. A total of twelve different scenarios are investigated and the results are discussed

Optimization and Analysis of Underactuated Linkage Robotic Finger

In this study it is required to maximize the transmission performance, which is leading to increase the transmitted torque from the actuated joints to the underactuated joints through transmission mechanism. Accordingly grasping forces in finger phalanges will increase. Studying the four bar mechanism parameters of a specific configuration within defined limits led to the linkage transmission defect parameter, which play a major role in deciding the linkage performance, used as optimization objective function to be minimized. This study presents an optimization procedure carried out using matlab fminunc function, formulated by using Freudenstein's equations to be applied on a (Cassino-Underactuated-Multifinger-Hand) design , using  one finger and a thumb .A mathematical model of grasping forces of the finger were introduced taking into account the solid links in the( Ca.U.M.Ha)  robotic finger . Keywords: Linkage , underactuated, optimizatio

Design Optimization of Slider-Crank Mechanisms Subject to Coulomb Bearing Friction

Optimization techniques are applied to the design of slider-crank mechanisms operating as single acting compressors subject to Coulomb bear ing friction. The dynamic force analysis is performed by the solution of a set of nonlinear equations in dimensionless form. The optimization re sults presented are for various cases of inertia, friction, and external loading. The optimization procedure developed minimizes a weighted sum of the input work and bearing shear stress by adjusting the mechanism\u27s dimensions. The independent dimensions that are varied are the connecting rod length, the offset, and the three bearing radii. The results of the optimization are different optimum slider-crank linkage configurations, where each link age minimizes a different level of the work-stress combination. This optimization procedure can be useful in the design of slider- crank mechanisms employed in compressors. Further, the method can be ex panded to other mechanism types and loading forms

A cryocooler for applications requiring low magnetic and mechanical interference

A very low-power, low-interference Stirling cryocooler is being developed based on principles and techniques described in several previous publications over the last four years. It differs in several important details from those built previously. It uses a tapered displacer based upon an analytical optimization procedure. The displacer is driven by an auxiliary piston and cylinder (rather than by mechanical linkage) using some of the working fluid itself to provide the driving force. This provides smooth, vibration-free motion, and, more importantly, allows complete mechanical and spatial separation of the cryostat from the pressure-wave generator. Either of two different pressure-wave generators can be used. One is a non-contaminating, unlubricated ceramic piston and cylinder. The other is a compressed-air-operated rubber diaphragm with motor-driven valves to cycle the pressure between appropriate limits

Computer-Aided Design of Coupler-Driven Watt I and Tolerance Synthesis for Four-Bar Linkages

Theory to rectify circuit defects in rocker-crank and double-rocker at the synthesis level is described based on the angular joint displacements. It complements the crank-rocker and double-crank circuit rectification to complete the circuit rectification of four-bar linkages. The procedure utilizes the algebraic method where special points followed by a line construction procedure are employed to validate the range of the critical angle that can identify the circuit defects as a function of the design positions prior to the completion of the linkage. A complete procedure of the rectified synthesis of the coupler-driven Watt I six-bar linkage to pass through the pre-defined four design positions is presented. This is done by de-coupling the six-bar mechanism as a coupler-driven and crank-driven four-bar linkages with common links. The vector component mechanism modeling method is applied to these linkages where the dyad and triad synthesis approaches are adopted in conjunction with the vector-algebraic method to find the solutions. The linkage with the coupler-driver is initially synthesized and rectified, then followed by the crank-driven four-bar linkage. The six-bar linkage is thus insured to assemble free of circuit, branch, and order defects. Optimization techniques are used to render the best solution linkages according to the specified design criteria. The process is coded and added to a mechanism design platform--RECSYN that allows a designer to synthesize coupler-driven Watt I linkages and the new circuit rectification theory is also applied in the program. A methodology to determine the optimum link length tolerance and joint clearance distributions in four-bar linkages for motion generation with specified structural error in order to manufacture the linkages is proposed. A stochastic model incorporated with tolerances and clearances for four-bar motion generation is proposed. The statistical characteristics of the random variables in the model are discussed. The mechanical error of four-bar motion generation as a function of statistical properties of random variables is defined. The tolerances and clearances are obtained as a result of solving an optimization problem with the objective function of link length tolerances and joint clearances and structural error as constraints. A FORTRAN code is written based on the proposed theory and ADS is employed as an optimization design tool. With this program, optimum link length tolerance and joint clearance distribution can be computed when the user input the required linkage information and structural errors. Examples of assigning tolerance and clearance for four-bar motion generation are presented to demonstrate the application of the method

Hybrid Optimization Based Mathematical Procedure for Dimensional Synthesis of Slider-Crank Linkage

In this paper, an optimization procedure for path generation synthesis of the slider-crank mechanism will be presented. The proposed approach is based on a hybrid strategy, mixing local and global optimization techniques. Regarding the local optimization scheme, based on the null gradient condition, a novel methodology to solve the resulting non-linear equations is developed. The solving procedure consists of decoupling two subsystems of equations which can be solved separately and following an iterative process. In relation to the global technique, a multi-start method based on a genetic algorithm is implemented. The fitness function incorporated in the genetic algorithm will take as arguments the set of dimensional parameters of the slider-crank mechanism. Several illustrative examples will prove the validity of the proposed optimization methodology, in some cases achieving an even better result compared to mechanisms with a higher number of dimensional parameters, such as the four-bar mechanism or the Watt’s mechanism.The authors wish to acknowledge financial support received from the Spanish government through the Ministerio de Economía y Competitividad (Project DPI2015−67626-P (MINECO/FEDER, UE)), the support for the research group through Project Ref. IT949−16, provided by the Departamento de Educación, Política Lingüística y Cultura from the regional Basque Government, and the Program BIKAINTEK 2020 (Ref. 012-B2/2020) provided by the Departamento de Desarrollo Económico, Sostenibilidad y Medio Ambiente from the regional Basque Government