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In this paper, general strategies are presented by which a multi-domain, multi-objective, mechanism-based optimization problem may be efficiently formulated and solved by means of a genetic algorithm. These strategies include integration of traditional precision position techniques with genetic optimization, efficient selection of design variables and search bounds, and a nested optimization structure. A case study illustrating these methods is presented in which a hydraulic rescue spreader is simultaneously optimized for four objectives relating to structural efficiency and kinematic behavior. The solution obtained is shown to be equal or superior to a comparable commercially available device with respect to all four objectives. [ABSTRACT FROM AUTHOR]

Abstract: The switch-mode continuously variable transmission is the mechanical analog of a DC–DC boost converter circuit and allows coupling a high speed flywheel to a mechanical load. The system requires a high-frequency clutch with a variable duty ratio and low slip during engagement and disengagement. In this paper, the synthesis and baseline testing of a novel digital clutch for this application are presented. The custom clutch design utilizes a double dwell axial cam with a profile that varies with radius. The duty cycle of the clutch is controlled through positioning the radial location of three translating followers, connected through a linkage. The axial clamping force of the clutch is generated through designed deflection of the system components and springs in series with the cam followers. Through baseline testing, the clutch was operated at angular velocities up to 45rad/s, creating clutch switching frequencies up to 22Hz. The average clutch efficiency at 20% duty cycle was 55%, yet the efficiency is highly dependent on the duty cycle and can be improved in future testing. [Copyright &y& Elsevier]

Transmission angle control is well studied for both crank rocker and Grashof crank slider mechanisms. However, non-Grashof slider-crank mechanisms have received less attention. For these mechanisms, the fully rotatable crank constraint is removed increasing the complexity of the problem. Furthermore, methods of linkage synthesis by optimization are becoming more prevalent. When optimizing a mechanism, it is important to prevent the evaluation of non-constructible and undesirable linkages. Presented here is a method of solution rectification by means of transmission angle control for slider-crank mechanisms which can be used to parameterize a problem to prevent the evaluation of invalid linkages. The solution is kept general to include fully rotatable crank slider mechanisms as well. The solution considers both crank driven and slider driven mechanisms as well as a reversible driver mechanism. An example is provided to demonstrate the method. It will be shown that by defining a transmission angle, valid linkages can be generated preventing the evaluation of invalid solutions. [ABSTRACT FROM AUTHOR]

• Forward and inverse cam generation methods for cam-linkage mechanism. • Cam-rocker-slider mechanism for function generation. • Forward method specifies cam shape, inverse method specifies linkage output. • Evaluation of cam profiles for the design of hydraulic motor. • Case study of hydraulic motor with radially spaced linkage mechanisms. This paper presents a comparison between the forward and inverse cam generation methods applied to the design of a multi-lobed cam-rocker slider mechanism for function generation. In the forward method, the cam profile is specified directly and then the linkage output is determined using kinematics. In the inverse method, the trajectory of the output link is specified first and then the cam profile is determined using inverse linkage kinematics. First, the cam-linkage mechanism is introduced, and relevant kinematic equations are presented. Then, the cam generation methods are thoroughly explained. The two cam generation methods are applied to a case study of a hydraulic motor using a multi-lobed cam and multiple linkage mechanisms. While the forward method has direct control of the cam shape, the inverse method has direct control of the linkage output and offers an advantage in calculation speed. For the mechanism selected, the cam designed with the inverse method achieved a reduction of at least 50.97% in the torque ripple when compared to the cam designed with the forward method. [ABSTRACT FROM AUTHOR]