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.

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.

Geometric and algebraic approach to the inverse kinematics of four-link manipulators

Robotica ◽  
1994 ◽  
Vol 12 (1) ◽  
pp. 59-64 ◽  
Author(s):  
I. Uzmay ◽  
S. Yildirim
Keyword(s):  
Inverse Kinematics ◽  
Robot Manipulator ◽  
Algebraic Approach ◽  
Geometric Approach ◽  
Inverse Kinematics Problem ◽  
Angular Velocities ◽  
Definite Difference ◽  
Cubic Polynomials ◽  
Derivatives Of ◽  
Algebraic Approaches

This paper presents an example of the application of geometric and algebraic approaches to the inverse kinematics problem of four-link robot manipulators. A special arm configuration of the robot manipulator is employed for solving the inverse kinematics problem by using the geometric approach. The obtained joint variables as angular positions are defined in the form of cubic polynomials. The other kinematic parameters of the joints, such as angular velocities and angular accelerations, are the time derivatives of these polynomials. It is evident that there is no definite difference between the results of the two approaches. Consequently, if an appropriate arm configuration for the geometric approach can be established, the inverse kinematics can be solved in a simpler and shorter way.

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.

scholarly journals Three-Dimensional Upper Body Kinematics and Inter-articular Kinematic Sequence During a Canoe Polo Throw

2021 ◽  
Vol 3 ◽  
Author(s):  
Najoua Assila ◽  
Cyril Delavallade ◽  
Yoann Blache ◽  
Christian Berger-Vachon ◽  
Philippe Collotte ◽  
...  
Keyword(s):  
Angular Velocity ◽  
Inverse Kinematics ◽  
Three Dimensional ◽  
Statistical Parametric Mapping ◽  
Vertical Axis ◽  
Axial Rotation ◽  
Upper Body ◽  
Parametric Mapping ◽  
Overhead Sports ◽  
Angular Velocities

Canoe polo is an increasingly popular discipline requiring both kayaking and ball-handling skills. While the kinematics of the upper body during throw has been investigated for several overhead sports, the canoe polo throw has still to be studied. Therefore, the aim of this study is to analyze the canoe polo throw kinematics in terms of angles and inter-articular sequencing to understand its specificity. A secondary aim was to investigate whether adding pelvis mobility has an impact. Nineteen male players of canoe polo were equipped with reflective body markers for the throw analysis. They performed 5 throws with the pelvis fixed and 5 throws with additional pelvic mobility in rotation around a vertical axis. Inverse kinematics was performed with OpenSim providing pelvis, trunk, and glenohumeral rotations. Angular velocities were calculated to build the inter-articular sequences relative to these throws. Statistical parametric mapping was used to assess the effect of pelvis mobility on the throwing kinematics. Similar kinematics patterns as in other overhead sports were observed, however, a different inter-articular sequence was found for the canoe polo throw with a maximal angular velocity occurring sooner for the thorax in axial rotation than for the pelvis in rotation. While the limitation of rotation of the pelvis around a vertical axis has an influence on the pelvis and trunk kinematics, it did not modify the kinematic sequence.

scholarly journals Towards Washout Filter Concepts for Motion Simulators on the Base of a Stewart Platform

PAMM ◽  
2011 ◽  
Vol 11 (1) ◽  
pp. 955-956 ◽  
Author(s):  
Klemens Springer ◽  
Hubert Gattringer ◽  
Hartmut Bremer
Keyword(s):  
Stewart Platform ◽  
Washout Filter

scholarly journals Backstepping controller for laser ray tracking of a target mobile robot

2020 ◽  
Vol 53 (7-8) ◽  
pp. 1540-1547
Author(s):  
Yun Ling ◽  
Jian Wu ◽  
ZhanQiang Lyu ◽  
Pengwen Xiong
Keyword(s):  
Mobile Robot ◽  
Tracking Control ◽  
Inverse Kinematics ◽  
Proportional Integral Derivative ◽  
Proportional Integral Derivative Controller ◽  
Angular Velocities ◽  
Backstepping Controller ◽  
Skid Steering ◽  
The Relationship ◽  
Shooting Ranges

Tracking control, which is applied to the target mobile robots in the process of rushing toward the trainees, is one of the critical technologies in the advancement of anti-terrorist training. Considering the disadvantages of various types of traditional tracking methods, this paper proposes a novel laser ray tracking mechanism and a backstepping controller for the target mobile robot that is used in shooting ranges. The mechanism and principle of the laser ray tracking is illustrated in detail. Based on the unique structure, the light intensity distributions are measured to further locate the laser spots on the cut-ray boards. Then, the relationship between the positions of the laser spots on the cut-ray boards and the pose of the target mobile robot is demonstrated. According to the features of the tracking situation, a backstepping controller is designed to achieve the laser ray tracking. After that, the inverse kinematics of the wheeled skid-steering mobile robot is analyzed to map the linear and angular velocities of the robot to the velocities of its left wheels and right wheels. The conventional proportional–integral–derivative controller is applied in the experiments to compare with the proposed backstepping controller. The experimental results show that the proposed controller is more robust, and converges faster for the laser ray tracking.

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