Model-based design of flexure hinges for rectilinear guiding with compliant mechanisms in precision systems

Flexure hinges are often used in precision systems because in addition to other advantages they allow the simple adjustment of a required deformation and motion behavior of monolithic compliant mechanisms by geometrical design. In this contribution, the potential of improving the motion precision as well as the motion range by specific design of the flexure hinge dimensions and in particular of their notch contour is described using the example of two four-bar compliant rectilinear guiding mechanisms. To verify the detailed investigation of the notch contour as a recent approach of the compliant mechanism synthesis, the model-based FEM results are compared to the guiding error of the rigid body counterparts.Festkörpergelenke werden vielfach in Präzisionssystemen eingesetzt, weil sie die einfache Einstellung eines gewünschten Verformungs- und Bewegungsverhaltens von monolithischen nachgiebigen Mechanismen durch geometrische Gestaltung ermöglichen. Im Hinblick auf einen vergrößerten Bewegungsbereich und eine erhöhte Bewegungspräzision wird in diesem Beitrag das Potenzial der Gestaltung der Abmessungen und insbesondere der Aussparungskontur der Festkörpergelenke beispielhaft an zwei nachgiebigen Geradführungsmechanismen beschrieben. Um den neuen Syntheseansatz der modellbasiert ermittelten FEM-Ergebnisse zu verifizieren, werden die Führungsfehler mit denen der Starrkörpermechanismen verglichen

OPTIMAL SYNTHESIS OF A MANIPULATOR USING TWO COMPETITIVE METHODS

This paper defines a program realization for finding the optimal geometry of a planar Z-mechanism. The paper shows the mathematical procedure for defining the objective function, the constraint function and the search fields which are used for solving the optimization problem. Starting from the solutions in practice, a numerical example is given to determine an optimum design with four optimization parameters. All the optimization parameters are geometric on the mechanism for defining the bucket position. The problem is solved by two different numerical methods - the method of formal search of hyperspace (passive scanning method) and the approximate method of Sequential Quadratic Programming - SQP (applying the function fminmax of the Matlab optimization toolbox). The verification is performed with animation using software for geometric modeling. The results are graphically illustrated

The improvement of hygienic and technological quality of raw milk

Poslije mužnje moguća je kontaminacija sirovog mlijeka sa mikroorganizmima. Da bi ustanovili stepen kontaminacije sirovog mlijeka uzeli smo 100 uzoraka iz sabirne cisterne u stoji i 50 uzoraka istih sirovih mlijeka iz transportne cisterne i odredili ukupan broj mikroorganizama i prisustvo pojedinih vrsta patogenih mikroorganizama u njima. Ispitivanja su pokazala da u pogledu pojedinih mikrobioloških karakteristika postoje značajne razlike između sirovog mlijeka uzorkovanog iz sabirne cisterne u štali i sirovog mlijeka uzorkovanog iz transportne cisterne na prijemnoj rampi mljekare.The contamination of raw milk with microorganisms is possible after the completion of milking. In order to determine the level of contamination of raw milk, 100 samples were taken from the transportation tank, and the total number of microorganisms and presence of various pathogenic microorganisms were determined. Tests have shown that significant differences exist between raw milk samples from the collecting tank in the stable, and those samples taken from the transportation tank when entering the dairy

Analytical model of conductive graphite foam based sensors characteristics

Sensors play an important role in the control systems, because they provide the necessary information from surroundings to the controller of an automated systems. Today’s sensors are very sophisticated, with high accuracy, fast acquisition rate and good signal-to-noise ratio. But most of these sensors are too much expensive. Low cost sensor for measuring the force (pressure) or the displacement could be realized by utilizing conductive elastomer that exhibits property of changing the electrical resistance when the elastomer is deformed. This paper introduced a novel conductive graphite foam based sensors. The sensors are formed by inserting two thin copper wires within conductive foam, parallel to each other at the two opposite sides. The main problem of conductive foam based sensors is that the force-electrical resistance characteristic, or the displacement-electrical resistance characteristic, of conductive foam is highly nonlinear. This paper presents the analytical model of the conductive graphite foam sensors for measurement of the displacement. By measuring the changes in the electric resistance between two points of the foam and using the developed analytical model it should be possible to accurately estimate the displacement when the conductive foam is deformed

Razvoj adaptivnog gipkog sistema za upravljanje oblikom radne površine

This dissertation presents the new solution of adaptive compliant system i.e. adaptive compliant structure with embedded actuators and sensors that is capable of changing its shape on demand. By embedding actuators and sensors within the compliant mechanism structure, the system can realize both sensing (via sensors) and appropriate response (via actuators and internal structure) to the unknown external environment, thus making the system adaptive - ˝intelligent˝. In dissertation a computer-coded algorithm for the synthesis of the adaptive shape morphing compliant system is developed, where placement of actuators (type, orientation, size and location) is also included in the synthesise process. It is shown that obtained solution of adaptive compliant system can achieve multiple shapes of its output surface with tree embedded actuators; by using combination of different active actuators compliant system can realize more complex shapes of its output surface. Based on the obtained solution, the 3D model of adaptive compliant system with embedded actuators is designed. The nonlinear FEM simulations are performed to investigate the behaviour of the developed compliant system. The physical prototype of the adaptive shape morphing compliant structure with embedded actuators is manufactured as one monolithic structure and tested. Two possible applications of the developed compliant system are presented, for the adaptive compliant gripper and the shape morphing wing. The actuators and sensors that can easily be embedded within the complaint system structure are developed. Actuators are developed by using shape memory alloy wires, and sensors were developed by using conductive foam that can change its electrical resistance when deformed. The adaptive compliant system with embedded nitinol wire actuators and conductive foam sensors is tested, and it is shown that such compliant system can achieve multiple shapes of its output surface. The developed adaptive compliant system with embedded nitinol wire actuators and conductive foam sensors and with controller (which was also developed) represents highly embedded mechantronical system which has many advantages over existing solution of shape morphing structure

Razvoj adaptivnog gipkog sistema za upravljanje oblikom radne površine

This dissertation presents the new solution of adaptive compliant system i.e. adaptive compliant structure with embedded actuators and sensors that is capable of changing its shape on demand. By embedding actuators and sensors within the compliant mechanism structure, the system can realize both sensing (via sensors) and appropriate response (via actuators and internal structure) to the unknown external environment, thus making the system adaptive - ˝intelligent˝. In dissertation a computer-coded algorithm for the synthesis of the adaptive shape morphing compliant system is developed, where placement of actuators (type, orientation, size and location) is also included in the synthesise process. It is shown that obtained solution of adaptive compliant system can achieve multiple shapes of its output surface with tree embedded actuators; by using combination of different active actuators compliant system can realize more complex shapes of its output surface. Based on the obtained solution, the 3D model of adaptive compliant system with embedded actuators is designed. The nonlinear FEM simulations are performed to investigate the behaviour of the developed compliant system. The physical prototype of the adaptive shape morphing compliant structure with embedded actuators is manufactured as one monolithic structure and tested. Two possible applications of the developed compliant system are presented, for the adaptive compliant gripper and the shape morphing wing. The actuators and sensors that can easily be embedded within the complaint system structure are developed. Actuators are developed by using shape memory alloy wires, and sensors were developed by using conductive foam that can change its electrical resistance when deformed. The adaptive compliant system with embedded nitinol wire actuators and conductive foam sensors is tested, and it is shown that such compliant system can achieve multiple shapes of its output surface. The developed adaptive compliant system with embedded nitinol wire actuators and conductive foam sensors and with controller (which was also developed) represents highly embedded mechantronical system which has many advantages over existing solution of shape morphing structure

Razvoj adaptivnog gipkog sistema za upravljanje oblikom radne površine

This dissertation presents the new solution of adaptive compliant system i.e. adaptive compliant structure with embedded actuators and sensors that is capable of changing its shape on demand. By embedding actuators and sensors within the compliant mechanism structure, the system can realize both sensing (via sensors) and appropriate response (via actuators and internal structure) to the unknown external environment, thus making the system adaptive - ˝intelligent˝. In dissertation a computer-coded algorithm for the synthesis of the adaptive shape morphing compliant system is developed, where placement of actuators (type, orientation, size and location) is also included in the synthesise process. It is shown that obtained solution of adaptive compliant system can achieve multiple shapes of its output surface with tree embedded actuators; by using combination of different active actuators compliant system can realize more complex shapes of its output surface. Based on the obtained solution, the 3D model of adaptive compliant system with embedded actuators is designed. The nonlinear FEM simulations are performed to investigate the behaviour of the developed compliant system. The physical prototype of the adaptive shape morphing compliant structure with embedded actuators is manufactured as one monolithic structure and tested. Two possible applications of the developed compliant system are presented, for the adaptive compliant gripper and the shape morphing wing. The actuators and sensors that can easily be embedded within the complaint system structure are developed. Actuators are developed by using shape memory alloy wires, and sensors were developed by using conductive foam that can change its electrical resistance when deformed. The adaptive compliant system with embedded nitinol wire actuators and conductive foam sensors is tested, and it is shown that such compliant system can achieve multiple shapes of its output surface. The developed adaptive compliant system with embedded nitinol wire actuators and conductive foam sensors and with controller (which was also developed) represents highly embedded mechantronical system which has many advantages over existing solution of shape morphing structure

SOFTWARE FOR SYNTHESIS OF COMPLIANT MECHANISMS WITHOUT INTERSECTING ELEMENTS

A compliant mechanism is defined as a single piece structure that transfer motion or force through elastic deformation. The synthesis of this kind of mechanisms represents a challenging task, especially because their flexible segments usually must undergo large, nonlinear deflections which include difficult nonlinear analysis. In this paper the new software for synthesis of compliant mechanisms is developed. The software uses an improved topology optimization technique that is especially useful when the designer does not have a particular compliant mechanism already in mind. Intersection between elements in the compliant mechanisms obtained by using existing topology optimization technique often increases stiffness of the structure which need to be flexible. The topology optimization technique is improved in the software so that compliant mechanisms without intersecting elements are obtained. The methodology that software uses and its capability will be shown on the examples of synthesis of the compliant gripper and the compliant displacement inverter