Papers by Keyword: Stewart Platform

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Authors: Ahmad Majdi Abdul-Rani, Subramaniam Krishnan, T. Nagarajan, T.V.V.L.N. Rao
Abstract: In this paper, the analyses results on the behavior of Shape Memory Alloy (SMA) in Medical application were carried out. SMA materials are known by their aptitude to recover its original form when undergone suitable thermal changes. SMA is widely used in robotics, automotive, aerospace and it can be a potential application in biomedical engineering due to its low cost, high corrosion resistance and can be easily integrated with human applications. Stewart platform with two different upper platform diameters of 150 mm and 300 mm were designed, fabricated and used as experimental test-rig. Inverse kinematic calculations were carried out to identify a maximum deflection of Stewart platform that can promote continuous passive motion (CPM). The 150 mm base diameter Stewart platform is found to be the suited for generating substantial displacement between ankle and foot. The mechanical changes induced by the heat could be used as a property in manufacturing of rehabilitation device for foot and ankle.
Authors: Aleksander Gwiazda, Krzysztof Herbuś, Gabriel Kost, Piotr Ociepka
Abstract: Modern CAD/CAE allows supporting the process of design and construction at many stages, from concept development through specific engineering calculations to the creation of design documentation. In the case of constructing mechanisms, the kinematic and dynamic analysis of the proposed system is an important step in the introduced process. The paper presents an example of the kinematic and dynamic analysis of the Stewart platform using Siemens NX software [1, 2]. The conducted investigation has allowed determining the geometric characteristics of the mechanism of the Stewart platform as well as the geometric parameters of actuators and their location. A dynamic analysis of the platform helped with establishing the required motor forces for realizing the moves with the maximum speed and acceleration. This allowed the initial selection of the parameters of electric motors. Traffic analysis was also performed for investigating collisions between the parts of the hexapod and between the hexapod and its environment.
Authors: Yu Yang, Shu Tao Zheng, Jun Wei Han
Abstract: To improve the fidelity of the motion cueing in the flight simulator, an improved adaptive motion drive algorithm was presented. In this algorithm, the motion limits of single degree of freedom, which calculate according to the Stewart platform kinematics, was introduced in to reduce the possibility of actuators exceeding theirs motion limits. So the algorithm parameters can be tuned more “open up” to improve the fidelity of motion cueing. The improved motion drive algorithm was verified in the airplane takeoff and landing. The results show that the algorithm can improve the fidelity when the platform has more available motion space; and can avoid exceeding motion limits when the platform has small motion space.
Authors: Jian Qin Mao, Chao Li, Hui Bin Xu, Cheng Bao Jiang, Lin Li
Abstract: A six degree-of-freedom (DOF) Stewart platform is constructed, which consists of six TbDyFe alloy magnetostrictive actuators, and applied to active vibration control. To control the smart structure, a real time computer control system is built. An improved adaptive filtering algorithm is proposed in this paper, which is used for the computer control system. The results of experiments show that the smart structure and the proposed algorithm are efficient for active vibration control. More than 30 dB of vibration attenuation is achieved in real-time experiments.
Authors: Zhi Yong Qu, Zheng Mao Ye
Abstract: This paper presents an algorithm to develop a mission-based optimal joint space control for a Stewart manipulator. The proposed algorithm consists of two optimization phases. The first phase seeks an inverse kinematic model and controller for the closed loop control of a Stewart manipulator using a feedback value. The second phase optimally tunes the controller called amplitude phase control (apc) in order to meet special mission requirements. Iteration algorithm is used in this phase as the optimization method. The proposed amplitude phase control optimal joint space control shows the capability to reduce the error in tracking the sin signals.
Authors: Zhi Yong Qu, Zheng Mao Ye
Abstract: Stewart platforms have recently attracted attention as simulator and machine tools because of their conceptual potentials in high motion dynamics and accuracy combined with high structural rigidity due to their closed kinematic loop. This paper, composed of inverse kinematic design and optimization, attempts to ground the foundation on dynamics design and choice in the future.
Authors: Yu Hui Zhang, Li Wen Guan, Li Ping Wang, Yong Zhi Hua
Abstract: The forward kinematics analysis of parallel manipulator is a difficult issue, which has been studied by many researchers recently. In this paper, in order to solve the difficult issue, a new computing method with higher calculation accuracy, good operation steadiness and faster speed is mentioned. Firstly, the mathematical model of direct kinematics of the Stewart platform is founded, which is nonlinear equations. Secondly, with the rapid development of artificial intelligence technology, Memetic algorithms (MA) are applied to solve the systems of nonlinear equations more and more, replacing the traditional algorithms. MA is a kind of meta-heuristic algorithm combined genetic algorithms (GA) with local search at the end of iteration. Finally, the validity of this algorithm has been testified by simulating iteration operation. The numerical simulation shows that MA can surely and rapidly get global optimum solution and greatly improve convergence rate. Thereby, MA can be widely used as a general-purpose algorithm for solving the forward kinematics of parallel mechanism.
Authors: Thilo Pirling, Giovanni Bruno, Philip J. Withers
Abstract: SALSA (Strain Analyser for Large Scale engineering Applications) is a novel instrument for strain imaging at the high flux neutron reactor of the Institut Max von Laue – Paul Langevin (ILL) in Grenoble, France. It is the first of its kind that uses a precise robotic sample stage for sample manipulation. In addition to standard xyz-translation it provides tilts up to ±30° about any horizontal axis. Its load capacity is more than 500 kg and samples up to 1.5 m in length can be scanned with high accuracy. Thanks to a double focusing monochromator and supermirror guide count times are very short. A broad wavelength range, variable beam optics, including radial focusing collimators for high lateral resolution, make it a very flexible instrument for a large variety of strain imaging applications in small and large specimens. The instrument has been commissioned in 2005 and is open for access by a peer review proposal system and as well by industry. The paper describes the important aspects of the instrument and results from the first experiments.
Authors: Wacław Banaś, Krzysztof Herbuś, Gabriel Kost, Andrzej Nierychlok, Piotr Ociepka, Daniel Reclik
Abstract: The paper presents the implementations of the control algorithm of a virtual system (Stewart platform) in the CAD/CAE system (Siemens NX) and in the NI LabVIEW supervisory and control system. The combination of both systems enables the virtual simulation and presentation of the results in relation to the chosen in the work virtual model of the Stewart platform. The virtual model of the Stewart platform with the imposed constraints and mobility limitations was built in the Siemens NX CAD/CAE system. Each of the modeled elements is based on the real components of the car simulator prepared for the persons with mobility impairments. The chosen model of a Stewart platform is a system with six degrees of freedom that is often used to build various types of simulators (e.g. flight, car). Using the NI LabVIEW software, a mathematical model of the Stewart platform was built and inverse kinematics task was implemented in relation to the model of the platform. The created mathematical model that describes the behavior of the Stewart platform was used to determine the inputs to the control system of platform actuators.
Authors: Jing Wei Hou, Ding Xuan Zhao, Ying Zhao, Yu Xin Cui
Abstract: a virtual prototype program of hydraulic Stewart force feedback master-slave system is developed to solve the modeling problems when plant developing and controller design. The following work is done based on the Stewart manipulator simulation program built in Matlab/SimMechanics platform: 1. Master/slave force feedback control framework is built based on the relationship between force on cylinders and upper platform.; 2. A new Stewart platform with load force model on the upper platform hydraulic servo system is built as the slave hand. The validity of the functions is verified by simulation experiment.
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