scholarly journals USING THE INVERSE KINEMATICS AND THE MATLAB SYSTEM FOR CONTROLLING THE STEWART PLATFORM

2017 ◽  
Vol 2 (№8 2017) ◽  
pp. 216-220
Author(s):  
A.Zh. Seydakhmet ◽  
A.E. Abduraimov ◽  
A.N. Kamal
Keyword(s):  
Inverse Kinematics ◽  
Stewart Platform

scholarly journals An algorithm to solve the inverse kinematics to a stewart platform

2020 ◽  
Vol 11 (2) ◽  
pp. 263
Author(s):  
Florian Ion Tiberiu Petrescu ◽  
Relly Victoria Virgil Petrescu
Keyword(s):  
Inverse Kinematics ◽  
Stewart Platform ◽  
Point Of View ◽  
Mobile Systems ◽  
Relative Movement ◽  
Analytical Geometry ◽  
Method Of Calculation ◽  
Parallel Structures ◽  
Geometry Method ◽  
Exact Analytical Method

Mechanical systems in motion type parallel structures are solid, fast and accurate. Between mobile systems parallel the best known and used system is that of a Stewart platform, as being and the oldest system, quickly, solid and accurate. The paper presents a few main elements of the Stewart platforms. In the case where a motto element consists of a structure composed of two elements in a relative movement from the point of view of the train of propulsion and especially in the dynamic calculations, it is more convenient to represent the motto element as a single moving item. The paper presents an exact, original analytical geometry method for determining the kinematic and dynamic parameters of a parallel mobile structure. Compared with other methods already known, the presented method has the great advantage of being an exact analytical method of calculation and not one iterative-approximately.

scholarly journals Analysis and control of a Stewart platform as base motion compensators - Part I: Kinematics using moving frames

2021 ◽  
Author(s):  
Takeyuki Ono ◽  
Ryosuke Eto ◽  
Junya Yamakawa ◽  
Hidenori Murakami
Keyword(s):  
Lie Group ◽  
Inverse Kinematics ◽  
Center Of Mass ◽  
Base Plate ◽  
Stewart Platform ◽  
The Body ◽  
Scale Model ◽  
Moving Frames ◽  
Coordinate Frames ◽  
Control Application

AbstractKinematics and its control application are presented for a Stewart platform whose base plate is installed on a floor in a moving ship or a vehicle. With a manipulator or a sensitive equipment mounted on the top plate, a Stewart platform is utilized to mitigate the undesirable motion of its base plate by controlling actuated translational joints on six legs. To reveal closed loops, a directed graph is utilized to express the joint connections. Then, kinematics begins by attaching an orthonormal coordinate system to each body at its center of mass and to each joint to define moving coordinate frames. Using the moving frames, each body in the configuration space is represented by an inertial position vector of its center of mass in the three-dimensional vector space ℝ3, and a rotation matrix of the body-attached coordinate axes. The set of differentiable rotation matrices forms a Lie group: the special orthogonal group, SO(3). The connections of body-attached moving frames are mathematically expressed by using frame connection matrices, which belong to another Lie group: the special Euclidean group, SE(3). The employment of SO(3) and SE(3) facilitates effective matrix computations of velocities of body-attached coordinate frames. Loop closure constrains are expressed in matrix form and solved analytically for inverse kinematics. Finally, experimental results of an inverse kinematics control are presented for a scale model of a base-moving Stewart platform. Dynamics and a control application of inverse dynamics are presented in the part II-paper.

Design and kinematic analysis of a rotary positioner

Robotica ◽  
2006 ◽  
Vol 25 (1) ◽  
pp. 75-85 ◽  
Author(s):  
Borys Shchokin ◽  
Farrokh Janabi-Sharifi
Keyword(s):  
Kinematic Analysis ◽  
Inverse Kinematics ◽  
Parallel Manipulator ◽  
Stewart Platform ◽  
Optimal Combination ◽  
Variable Length ◽  
Mobile Platform ◽  
Constant Length ◽  
Forward And Inverse Kinematics ◽  
Circular Base

A rotary positioner (RP) is a type of parallel manipulator that is similar to a Stewart Platform. Instead of having variable-length bars, however, an RP has constant-length limbs located between a mobile platform as well as six circular motors distributed on a circular base. This paper offers a detailed investigation of an RP, focusing on its mechanism and analyzing its forward and inverse kinematics. It also computes an RP's constant orientation and orientation workspaces, taking into account the constraints imposed by passive joints and links interference. The optimal combination of the main parameters for an RP's maximum possible translation and orientation is also provided.

Latency on a Stewart platform using washout filter

2018 ◽  
Vol 122 (1252) ◽  
pp. 1003-1019 ◽  
Author(s):  
R.C. Lemes ◽  
M. Moreira Souza ◽  
E.M. Belo ◽  
J.H. Bidinotto
Keyword(s):  
Inverse Kinematics ◽  
Stewart Platform ◽  
External Factors ◽  
Specific Force ◽  
Signal Delay ◽  
Washout Filter ◽  
Total Latency ◽  
Angular Velocities ◽  
Movable Platform ◽  
Aircraft Motion

ABSTRACTThe aim of this work is to investigate and quantify the latency on a Stewart Platform caused exclusively by a Classic washout filter. This washout filter is intended to recreate the sensations of motion caused by changes of translational and rotational acceleration that an aircraft can provide, due to changes in attitudes caused by external factors, and those caused by the pilot’s command. The input signal was generated by a FlightGear Simulator in order to obtain the specific forces and angular velocities of a Boeing 747 during a take-off procedure. These signals are then filtered by a washout filter and sent to the inverse kinematics of the movable platform, which will transform the aircraft motion sensations in platforms actuator position, thereby causing a certain signal delay. Experiments were performed in a Stewart Platform to obtain the latency caused by the mathematical modelling of the entire washout filter system. This latency are then compared to the latency caused by the control and dynamics of the platform’s actuators. Results indicate that the washout filter is the most responsible for the latency of the specific force signals to be reproduced by the platform in this experiment, and that the natural frequency and damping coefficient values must be properly estimated in order to optimise the total latency.

Inverse Kinematics and Geometric Relations of an Intelligent Modified Stewart Platform for Thrust Vector Control

Aerospace ◽  
2004 ◽  
Author(s):  
Mehrdad N. Ghasemi Nejhad
Keyword(s):  
Vector Control ◽  
Inverse Kinematics ◽  
Vibration Suppression ◽  
Intelligent System ◽  
Research Effort ◽  
Stewart Platform ◽  
Fine Tuning ◽  
Precision Positioning ◽  
Thrust Vector Control ◽  
Thrust Vector

Adaptive or intelligent structures which have the capability for sensing and responding to their environment promise a novel approach to satisfying the stringent performance requirements of future space missions. This research effort focuses on the development of an intelligent thruster mount structure with precision positioning and active vibration suppression capability for use in a space satellite. The intelligent thruster mount would utilize piezoelectric stacks and patches for precision positioning and vibration suppression to provide fine-tuning of position tolerance for thruster alignment and low transmissibility of vibration to the satellite structure. This vibration, if not suppressed, renders sensitive optical or measurement equipment non-operational until the disturbance has dissipated. This intelligent system approach would greatly enhance mission performance by fine tuning attitude control, potentially eliminating the non-operational period as well as minimizing fuel consumption utilized for position correction. The configuration of the intelligent thruster mount system is that of a modified Stewart platform. Precision positioning of this structure is achieved using active composite strut members that use piezoelectric stack actuators and extend or contract to tilt the top device-plate where the thruster is mounted. The geometric relationship between the Stewart platform and the modified Stewart platform is described, and an inverse kinematics analysis of the modified Stewart platform has been developed and is used to determine the required axial displacement of the active struts for the desired angular tilt of the top device-plate. The active struts can participate in precision positioning as well as vibration suppression of the top device-plate where the thruster, i.e., the source of the unwanted vibrations and misalignment, is mounted. The proposed Thrust Vector Control (TVC) intelligent platform offers a promising method for achieving fine tuning of positioning tolerances of a thruster as well as minimizing the effects of the disturbances generated during thruster firing in spacecraft such as a satellite.

Inverse kinematics analysis of 6 – DOF Stewart platform based on homogeneous coordinate transformation

2018 ◽  
Vol 522 (1) ◽  
pp. 108-121 ◽  
Author(s):  
Wang Wei ◽  
Zhang Xin ◽  
Han Li-li ◽  
Wang Min ◽  
Zhong You-bo
Keyword(s):  
Coordinate Transformation ◽  
Inverse Kinematics ◽  
Stewart Platform ◽  
Kinematics Analysis
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