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This paper presents the research and development of a 3–legged micro parallel kinematic manipulator (PKM) for positioning in micromachining and assembly operations. The structural characteristics associated with parallel manipulators are evaluated and the PKMs with translational and rotational movements are identified. Based on these identification...
Citations
... Stewart platform is a parallel manipulator with applications across various fields [1]. The foundational concept of the Stewart platform can be traced back to Gough, who pioneered a parallel system that resembled a tire testing apparatus [2]. ...
This study introduces an approach for modeling an arm of a Stewart platform to analyze the location of sections with a high deflection among the arms. Given the dynamic nature of the Stewart platform, its arms experience static and dynamic loads. The static loads originate from the platform's own weight components, while the dynamic loads arise from the movement or holding of equipment in a specific position using the end-effector. These loads are distributed among the platform arms. The arm encompasses various design categories, including spring-mass, spring-mass-damper, mass-actuator, and spring-mass-actuator. In accordance with these designs, joint points should be strategically placed away from critical sections where maximum buckling or deformation is prominent. The current study presents a novel model employing Euler's formula, a fundamental concept in buckling analysis, to propose this approach. The results align with experimental and numerical reports in the literature that prove the internal force of the platform arm is affecting the arm stiffness. The equal stiffness of an arm is related to its internal force and its deflection. The study demonstrates how higher levels of dynamic loading influence the dynamic platform, causing variations in the maximum arm's buckling deflection, its precise location, and the associated deflection slope. Notably, in platform arms capable of adjusting their tilt angles relative to the vertical axis, the angle of inclination directly correlates with deflection and its gradient. The assumption of linearity in Euler's formula seems to reveal distinctive behavior in deflection gradients concerning dynamic mechanisms.
... From the literature review, it can be observed that the modular method has been increasingly proposed to develop reconfigurable and self-repairable robotic systems [14], while only a few researchers have used it to deal with problems faced by flexure-based mechanisms. C.C. Ng designed a 3-UPU parallel MPS based on a fixed-dimension module and varied-dimension module unit for micro-manufacturing assembly and verified modular architectures which have the same control performance as the monolithic one [15]. J.J. Yu proposed a method to design large displacement flexure-based MPSs based on ...
... To clarify this point, the introductions of these requirements are described in the following subsections. modular architectures which have the same control performance as the monolithic one [15]. J.J. Yu proposed a method to design large displacement flexure-based MPSs based on flexure block modules [16]. ...
With flexure-based micro-positioning stages (MPSs) being in high demand for high-precision applications, the performance and cost of flexure-based MPSs are two issues that urgently need to be addressed. In addition, the current MPSs are being developed toward complex spatial configurations, which further precludes monolithic fabrication. To address the aforementioned issues, modular MPSs using designed standardized modules are introduced in this paper. Firstly, the motivations are described, followed by the modular design. In addition, a new assembly concept analogy with composing compounds is proposed for guiding module assembly, including some proposed planar and spatial configurations. For validation, the static and dynamic performances of modular MPSs with respect to different modules and materials are presented as case studies. The proposed modular MPSs can provide better flexibility and functionality for further applications.
... Moreover, the Stewart platform's drawbacks are not insignificant and cause obstacles. Form limitation, direct complicated kinematic, control algorithm, and essential of the precise spherical joint are the most impediments [8,9]. ...
Because of the mechanical stress importance in the dynamic mechanisms, a Stewart platform is subjected to analysis to extract its critical stress areas in this study. The Stewart platform is an effective mechanism because it has been employed as a stabilizer or motion simulator. When this mechanism is subjected to static and dynamic forces in various applications, its components are at risk of failure in critical stress areas. This issue can be considered when designing, and parts failure can be prevented by knowing the essential points and stress values. This study is modeled the Stewart platform with specific dimensions and mechanical properties in Ansys Inc. and subjected it to static and Modal analysis with a numerical approach. The results present effective parameters that could be used in the mechanical design for this category of this platform.
... During the literature review, only a few researchers used modular method to design flexure-based mechanism and dealt with problems faced. Ng reported a parallel kinematic manipulator assembled by same modular units in modular configurations (Ng et al. 2006). Gendreau developed a modular architecture of micro-manufacturing systems for microassembly (Gendreau et al. 2010). ...
... However, for reconfigurable MPSs, some of the pre-given modules are optional, which depends on the design requirements. Overall, the configuration of reconfigurable MPSs can be adjusted to meet different functional and non-functional requirements, such as directional stiffness, dynamic performance, motion range, resolution, light weight and size of structure by changing modules, also the self-repair ability can be realized in this way (Ng et al. 2006). The remainder of the paper is arranged as follows: Sect. 2 answers why we need reconfigurable MPSs. ...
As the current trend in numerous industrial domains is to miniaturise products, micro-positioning stage(MPS) capable of performing micro-manipulation and micro-assembly tasks with sub-micrometer or nanometer precision is playing an increasing important role in these fields. In addition, well performances and low cost are two emergency issues need to be addressed for widely using flexure-based MPSs. However, the design and fabrication process for MPSs at present are costly both in time and money. Especially, the designed configurations are tailored to a specific application without flexibility. Thus, the purpose of this paper is to introduce a design of precision flexure-based reconfigurable MPSs which provide better flexibility and functionality and allows to reduce the time to market significantly. To begin with, performance requirements and benefits for reconfigurable MPSs are introduced. Then, some typical modules and their functions are introduced in detail. Finally, some selective stages assembled with function modules are proposed as case studies, for the purpose of validating the benefits of reconfigurable MPSs.
... The workspace is an important indicator for evaluating the working capacity of a robot with an end-effector and can be categorized into the translation workspace, orientation workspace, reachable workspace and dexterous workspace. For the parallel mechanism, the reachable workspace, defined as the set of reachable poses in an arbitrary orientation by the moving platform, was selected in most analyses [56][57][58]. ...
As the population ages, increasingly more individuals experience ankle disabilities caused by stroke and cerebral palsy. Studies on parallel robots for ankle rehabilitation have been conducted under this circumstance. This paper presents a novel parallel ankle rehabilitation robot with the key features of a simple configuration and actuator non-redundancy. The mechanical design is determined, and a prototype is built. Additionally, inverse position solution is addressed to calculate the workspace of the parallel robot. Jacobian matrices, mapping the velocity and force from the active joint space to the task space are derived, and kinetostatic performance indices, namely, motion isotropy, force transfer ratio and force isotropic radius, are defined. Moreover, the inverse dynamic model is presented using the Newton–Euler formulation. Dynamic evaluation index, i.e., dynamic uniformity, is proposed according to the derived Jacobian matrix and inertia matrix. Based on the workspace analysis, the parallel robot demonstrates a sufficient workspace for ankle rehabilitation compared with measured range of motion of human ankle joint complex. The results of the kinetostatic and dynamic performance analysis indicate that the parallel robot possesses good motion isotropy, high force transfer ratio, large force isotropic radius and relatively uniform dynamic dexterity within most of the workspace, especially in the central part. A numerical example is presented to simulate the rehabilitation process and verify the correctness of the inverse dynamic model. The simplicity and the performance of the proposed robot indicate that it has the potential to be widely used for ankle rehabilitation.
... The interference-free workspace is a crucial indicator to evaluate the working ability of an external fixator and can be defined as the size of the motion volume of the end frame without collision between different mechanical parts/human Fig. 2 Parametric description of (a) PDA-Uos (b) distraction rod body (i.e., the set of reachable postures in an arbitrary orientation by the end frame). The interference-free workspace of the PDA-Uos varies according to the spatial arrangement of the distraction rods and can be calculated by adopting numerical searching method [27][28][29][30] based on the inverse position solution while considering the constraint condition. This interference-free workspace calculation algorithm can be described in detail as: given a searching range in the threedimensional space, and then examine each point (corresponds to each posture of the end frame) within this range. ...
As a basic osteotomy technique, U osteotomy can be applied for certain complex foot and ankle deformities. Gradual correction cases using Ilizarov apparatus and Taylor Spatial Frame have been reported. This paper proposes a novel parallel distraction apparatus for U osteotomy (PDA-Uos) to supplement the correction equipment for surgeon. Designed with an adjustable structure, the PDA-Uos can adopt different assembly shapes (joint connection points). However, the influence of the change in assembly shape on interference-free workspace and self-structural performance of the external fixator have received little attention. To address this issue and enhance the selection of the most suitable assembly shape for patient, an algorithm to obtain the interference-free workspace of different assembly shapes is proposed based on the inverse position solution of the PDA-Uos. Additionally, correction ability indices are defined according to the requirements of accurately controlled motion and high structural stiffness of the external fixator along the correction path. The results of simulation cases indicate that the interference-free workspace and the correction ability vary according to the assembly shape and thus the proposed method can be used to select an assembly shape with sufficient workspace and the best correction ability before performing correction for a given patient.
Graphical abstract
... The configuration of the relevant combinations of auxiliary, periphery and basic modules is a matter that needs significant attention [12]. At present, there have been extensive researches on RMT and the modular design of machine tools [13][14][15][16][17][18][19][20][21]. An innovative approach of modular machine tool frames (MMTFs) equipped with microsystem technology was presented that aimed at enhancing flexibility of mutable production processes [22]. ...
The modular design of reconfigurable machine tools (RMTs) is the key enabling technology to reconfigurability. A systematic methodology for setting the constituent modules of RMTs is proposed in this paper. According to the structural and functional characteristics of the components that construct the machine tools, the geometry modules and the basic structure modules are generated, and on this basis, the conceptual autonomous functional modules of RMTs can be constructed. According to the reconfigurable manufacturing process planning for a part family, the optimal processing plans of a family of parts can be obtained, which include a series of processing segments. And through the generated motion-schemes of a RMT of each processing segment, the RMT configurations can be constructed from a set of the autonomous functional modules to meet the process requirements. Finally, a set of RMT modules with particular sizes and structures can be generated, which will be used to construct RMTs to accommodate required changes in existing products or parts. Taking the production of a gearbox part family as an example, the validity of the method is verified.
... PKM nin kalibrasyonu CMM (Coordinate Measuring Machine) kullanılarak yapılmıştır. Platformun hassasiyeti ve tekrar edilebilirliği 100 mikron olarak tanımlanmıştır [9]. ...
Stewart platforms are used in many areas in the industry. They are used as machine tools in recent years. Many machine manufacturers continue their research and development activities of machine tools in this structure which are more precise and functional. In this study, 3D model of 6x6 Stewart based machine tool design was generated. An alternative joint design has been realized in the model. It is stated that the alternative joint is prominently applied and can be easily applied at the cost which is low compared to the spherical joint used in the current situation. In addition to this, a software has been developed that can calculate leg lengths by using inverse kinematics method according to desired coordinate information with desired fixed and moving platform diameters of Stewart based machine tool. In the developed software, the length of the legs has calculated for various coordinate data.The alternative joint design has been successfully integrated into the 3D machine model, and the length of the legshave been successfully calculated in the developed software.
... En (Ng, Ong y Nee, 2006) se diseña y desarrolla un robot paralelo de 3 GDL con estructura 3-UPU. En el trabajo además se hace un análisis de las singularidades que presenta el diseño inicial del robot y, para su eliminación, se adiciona en el centro de la estructura paralela una articulación prismática pasiva quedando una nueva estructura PS-3UPU. ...
... Los autores demuestran que el robot construido es de total fiabilidad para el manejo de micro-herramientas industriales. (Ng, Ong y Nee, 2006) Por otro lado Brecht desarrolla una plataforma Gough-Stewart, pero de 3 GDL con el objetivo de efectuar la rehabilitación de tuberías de agua. El robot se encarga de mover un efector con un spray instalado el cual se le aplica al interior de las tuberías dañadas para su reparación. ...
... En (Ng, Ong y Nee, 2006) se diseña y desarrolla un robot paralelo de 3 GDL con estructura 3-UPU. En el trabajo además se hace un análisis de las singularidades que presenta el diseño inicial del robot y, para su eliminación, se adiciona en el centro de la estructura paralela una articulación prismática pasiva quedando una nueva estructura PS-3UPU. ...
... Los autores demuestran que el robot construido es de total fiabilidad para el manejo de micro-herramientas industriales. (Ng, Ong y Nee, 2006) Por otro lado Brecht desarrolla una plataforma Gough-Stewart, pero de 3 GDL con el objetivo de efectuar la rehabilitación de tuberías de agua. El robot se encarga de mover un efector con un spray instalado el cual se le aplica al interior de las tuberías dañadas para su reparación. ...
Technological progress and development in the field of robotics have made robots an indispensable factor for mankind in many ways, including education. This research presents the creation of a three-degree parallel robot prototype that can be used as a teaching medium, with a low-cost approach and the possibility of trajectory tracking. The robot is designed taking into account current trends in specialized literature, demonstrating the novelty of the subject. On the other hand, the equations of the inverse kinematics of the created robot that are validated after the experimental tests are obtained. The hardware that is part of the robot's control, as well as the data processing, satisfactorily meets the requirements demanded by the developed system. The interface created for handling the robot has three modes: Automatic, Manual and Pre-programmed Trajectory, which allows the platform to operate in different ways. Experimental tests were developed for each of the modes of operation and were validated by measuring roll and pitch angles through an Inertial Measurement Unit.
