Forward kinematics modelling of a parallel ankle rehabilitation robot using modified fuzzy inference

With the closed-loop structure, parallel manipulators possess some inherent advantages, such as high stiffness, enhanced dynamics, and compact structure. As a result, parallel manipulators gradually gain wide application. In the great variety of parallel manipulators, a kind of high-speed parallel robot, the limb of which is composed of active pendulum and passive parallelogram, gets popular and has realized industrial application firstly. Dynamic performance is the core of the high-speed parallel manipulator, which is usually illustrated through dynamic performance analysis with the aid of the index. Thus, developing reasonable dynamic performance indices is of great theoretical and practical significance for the high-speed parallel manipulator. In this paper, the Coefficient of Variation of joint-space Inertia (CVI) index is proposed to illustrate the acceleration consistency of each limb of the parallel manipulator. By taking the X4 high-speed pick-and-place parallel manipulator as object, the dynamic model and joint-space inertia matrix is established, and the dynamic performance analysis is carried out with the proposed CVI index and the existing Joint-Reflected Inertia (JRI) index. Simulation results illustrate changes of the dynamic performance of the X4 parallel manipulator, and reveal that the JRI index is well complemented with the CVI index. Finally, the workspace with good dynamic performance is discussed. This paper provides a new approach for dynamic analysis and optimal design of high-speed parallel manipulator. Limb Jacobian matrices of the X4 manipulator are given.Dynamic model and inertia matrix of the X4 manipulator are deduced.The CVI index is proposed to evaluate the dynamic performance.Dynamic performance of the X4 mahipulator is analyzed with indices.The workspace with good dynamic performance is disscussed.

Dynamic performance analysis of the X4 high-speed pick-and-place parallel robot

Dynamic modeling and control of a 6-DOF micro-vibration simulator

With the development of the parallel manipulator, inertia matching as an essential factor to realize good potentials of the parallel manipulator is taken serious gradually. However, neither definite inertia index nor inertia matching method has been proposed so far. In this paper, the above issues are discussed by taking the Stewart parallel manipulator as a study object. Firstly, adopting limb Jacobian matrices, the concise algebraic expression of the joint-space inertia matrix of the Stewart parallel manipulator is deduced, based on the dynamic modeling. Next, on the basis of the coupling analysis of the joint-space inertia matrix, the inertia index of the parallel manipulator, the Joint-Reflected Inertia, is proposed. Then, the practical inertia matching principles of the Stewart parallel manipulator are concluded on the basis of simulations, considering multiple factors, such as mechanical resonance frequency, acceleration torque and dynamic performance. Finally, the available range of the motor inertia is deduced, and the inertia matching of the Stewart parallel manipulator is finished as the case study. The inertia index and inertia matching method suggested in this paper can be further used in other parallel manipulators for dynamic analysis and motion system design.

Research on the inertia matching of the Stewart parallel manipulator

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Design Analysis and Control of Wearable Ankle Rehabilitation Robot

The development of a flight simulator is a challenging work because of its complexity and tremendous cost. We have accomplished a flight simulator composed of PC cluster and non-flight-certified COTS components and have proved its fidelity and coordination characters as a flight training device. The main purpose of this project is to find a low cost solution to man-in-the-loop flight simulation while still accomplishing a competitive high level of quality. This paper describes the architecture of the flight simulator, the software development tools and hardware platform. These software and hardware constituted a PC based simulation environment and made the expense of the simulation application affordable. We also present the simulation modeling process. And for the integrity of the cueing system, we established a virtual prototype of the motion system which should support the cockpit of the simulator. The integrated system gave us a chance to testify the fidelity and coordination of the simulator. The validation method and simulation results are presented finally to show the feasible design based on PC to carry out flight simulation application with high quality and low cost.

PC Based High Quality and Low Cost Flight Simulator

Object-oriented landing gear model in a PC-based flight simulator

Many systems have stiff characteristics To simulate such system in real-time demands solver of differential equation having small fixed step size to guarantee stability and accuracy even if it may cost large number of computing resource An adaptive variable minor step size Euler method is developed for real-time simulation It alternately uses forward Euler and backward Euler method based on morbid degree And then it divides fixed major step equally into multiple minor steps in according to local truncation error Because of this, it is more precise and more robust than classic Euler method While simulating large scale system, it realizes computing resource dynamic allocation in different sub-systems The advantageous abilities are verified by typical real-time simulation problems and the usage in a flight simulator These shows the method is very suitable for a long real-time simulation

Variable step euler method for real-time simulation

A 3-dof rotational parallel mechanism is presented which has three struts and three actuators and is a plasmodium of the Stewart platforms. The kinematics of this robot is derived, and the kinematics analysis is investigated based on analytical solution of the inverse kinematics and numerical solution of the forward kinematics. This mechanism is popular in the fields of simulators and parallel kinematics machines.

Kinematics Analysis of a 3-dof Rotational Parallel Mechanism

Previous biological experiments show that the fish use their muscles to stiffen their bodies for improving the swimming performance. Inspired by that, we propose a planar model of oscillatory propulsor with variable stiffness using hyper redundant serial-parallel mechanisms to mimic a fish. Our goal in the paper is to identify the swimming characteristics with respect to the body stiffness. Moreover, a simulation model is presented and its results show that the swimming performance is largely dependent on the body stiffness and the driven frequency. Our primary conclusions include: 1) when the driven frequency is closed to the design frequency, the robotic fish with the calculated body stiffness has a super swimming performance. 2) Driven at the design frequency, the forward speed of robotic fish is linearly proportional to the driving frequency and the Strouhal number is consistent with the experiment results 0.25<St<0.35.Copyright © 2013 by ASME

Jiang Hongzhou

Papers

PC Based High Quality and Low Cost Flight Simulator

Object-oriented landing gear model in a PC-based flight simulator

Variable step euler method for real-time simulation

Kinematics Analysis of a 3-dof Rotational Parallel Mechanism

A Study of the Planar Serial-Parallel Mechanism With Various Stiffness for a Biotic Compliant Fish