Structural Synthesis of Serial Robotic Manipulators Subject to Specific Motion Constraints

2010 ◽  
Author(s):  
Chin-Hsing Kuo ◽  
Jian S. Dai
Keyword(s):  
Coordinate System ◽  
Local Coordinate System ◽  
Robotic Manipulators ◽  
Robotic Manipulator ◽  
Industrial Applications ◽  
Global Coordinate System ◽  
Structural Synthesis ◽  
End Effector ◽  
Serial Manipulators ◽  
Motion Constraints

An intuitive approach for the structural synthesis of serial robotic manipulator subject to specific motion constraints is presented in this paper. According to the required f-DOF αRβT motion of the end-effector, for f = 2, 3, … or 6 and α, β = 0, 1, 2 or 3, all feasible serial-type robot structures can be systematically generated via the proposed method. The approach begins at the enumeration of joint connectivity, proceeds with the assignment of joint types, and continues by the consideration of motion constraints for the robot. A couple of examples, including the synthesis of the 3-, 4- and 5-DOF serial manipulators, are furnished for illustration. It shows that this method is especially exploitable when the end-effector is required to be immovable in certain orientations or directions with respect to either local coordinate system or global coordinate system. The result is particularly beneficial for practical industrial applications.

Consistent co-rotational framework for Euler-Bernoulli and Timoshenko beam-column elements under distributed member loads

2021 ◽  
pp. 136943322098663
Author(s):  
Yi-Qun Tang ◽  
Wen-Feng Chen ◽  
Yao-Peng Liu ◽  
Siu-Lai Chan
Keyword(s):  
Coordinate System ◽  
Stiffness Matrix ◽  
Traditional Method ◽  
Local Coordinate System ◽  
Frame Structures ◽  
Global Coordinate System ◽  
Single Element ◽  
Geometrically Nonlinear ◽  
Geometrically Nonlinear Analysis ◽  
Geometric Stiffness

Conventional co-rotational formulations for geometrically nonlinear analysis are based on the assumption that the finite element is only subjected to nodal loads and as a result, they are not accurate for the elements under distributed member loads. The magnitude and direction of member loads are treated as constant in the global coordinate system, but they are essentially varying in the local coordinate system for the element undergoing a large rigid body rotation, leading to the change of nodal moments at element ends. Thus, there is a need to improve the co-rotational formulations to allow for the effect. This paper proposes a new consistent co-rotational formulation for both Euler-Bernoulli and Timoshenko two-dimensional beam-column elements subjected to distributed member loads. It is found that the equivalent nodal moments are affected by the element geometric change and consequently contribute to a part of geometric stiffness matrix. From this study, the results of both eigenvalue buckling and second-order direct analyses will be significantly improved. Several examples are used to verify the proposed formulation with comparison of the traditional method, which demonstrate the accuracy and reliability of the proposed method in buckling analysis of frame structures under distributed member loads using a single element per member.

New repetitive motion planning scheme with cube end-effector planning precision for redundant robotic manipulators

Robotica ◽  
2021 ◽  
pp. 1-22
Author(s):  
Limin Shen ◽  
Yuanmei Wen
Keyword(s):  
Theoretical Analysis ◽  
Motion Planning ◽  
Robotic Manipulators ◽  
Robotic Manipulator ◽  
Repetitive Motion ◽  
End Effector ◽  
Difference Formula ◽  
Planning Scheme ◽  
Simulation Results ◽  
The Difference

Abstract Repetitive motion planning (RMP) is important in operating redundant robotic manipulators. In this paper, a new RMP scheme that is based on the pseudoinverse formulation is proposed for redundant robotic manipulators. Such a scheme is derived from the discretization of an existing RMP scheme by utilizing the difference formula. Then, theoretical analysis and results are presented to show the characteristic of the proposed RMP scheme. That is, this scheme possesses the characteristic of cube pattern in the end-effector planning precision. The proposed RMP scheme is further extended and studied for redundant robotic manipulators under joint constraint. Based on a four-link robotic manipulator, simulation results substantiate the effectiveness and superiority of the proposed RMP scheme and its extended one.

Development of Path Tracking Control Algorithm for a 4 DOF Spatial Manipulator Using PID Controller

2017 ◽  
pp. 314-327
Author(s):  
Pradeep Reddy Bonikila ◽  
Ravi Kumar Mandava ◽  
Pandu Ranga Vundavilli
Keyword(s):  
Pid Controller ◽  
Dynamic Models ◽  
Control Method ◽  
Robotic Manipulator ◽  
Industrial Applications ◽  
Path Tracking ◽  
End Effector ◽  
Straight Line ◽  
Feedback Control Method ◽  
Manipulator Arm

The path tracking phenomenon of a robotic manipulator arm plays an important role, when the manipulators are used in continuous path industrial applications, such as welding, machining and painting etc. Nowadays, robotic manipulators are extensively used in performing the said tasks in industry. Therefore, it is essential for the manipulator end effector to track the path designed to perform the task in an effective way. In this chapter, an attempt is made to develop a feedback control method for a 4-DOF spatial manipulator to track a path with the help of a PID controller. In order to design the said controller, the kinematic and dynamic models of the robotic manipulator are derived. Further, the concept of inverse kinematics has been used to track different paths, namely a straight line and parabolic paths continuously. The effectiveness of the developed algorithm is tested on a four degree of freedom manipulator arm in simulations.

Study on Establishment and Transformation of Coordinate System of Steel Structure in 3D Software

2014 ◽  
Vol 501-504 ◽  
pp. 2541-2545
Author(s):  
Kai Sun ◽  
Lu Shuang Wei ◽  
Li Xuan ◽  
Lun Gang Zhou
Keyword(s):  
Coordinate System ◽  
3D Visualization ◽  
Local Coordinate System ◽  
Steel Structure ◽  
Structure Design ◽  
Global Coordinate System ◽  
3D Space ◽  
Steel Members ◽  
Safe Condition ◽  
3D Software

The 3D visualization design of steel structure under the CAD environment needs to work in the global coordinate system (WCS), but design of various steel members in the 3D space must be completed in the local coordinate system (UCS), so it is perplexing for the conversion and calculation between UCSi (i=1,2,3....n) and WCS. It is proved that the maize grains are not polluted and food production is in safe condition. The article describes classification of several common coordinate systems, discuss the method of setting up coordinates system. Describe the process of type convertion of coordinate system in steel structure design and detailing softwares, and explained the advantage of the application in the real world project.

A Finite Element Formulation of Flexible Slider Crank Mechanism Using Local Coordinates

1994 ◽  
Author(s):  
Behrooz Fallahi ◽  
S. Lai ◽  
C. Venkat
Keyword(s):  
Rigid Body ◽  
Coordinate System ◽  
High Speed ◽  
Displacement Vector ◽  
Lagrange Equation ◽  
Local Coordinate System ◽  
Body Motion ◽  
Elastic Displacement ◽  
Global Coordinate System ◽  
Element Formulation

Abstract The need for higher productivity has lead to the design of machines operating at higher speeds. At high speed the rigid body assumption is no longer valid and the links should be considered flexible. In this work a method which is based on Modified Lagrange Equation for modeling flexible mechanism is presented. The method posses a more computational efficiency for not requiring the transformation from the local coordinate system to the global coordinate system. Also an approach using the homogeneous coordinate for element matrices generation is presented. The approach leads to a formalism where the displacement vector is expressed as a product of two matrices and a vector. The first matrix is a function of rigid body motion. The second matrix is a function of rigid body configuration. The vector is a function of elastic displacement. This formal separation helps to facilitate the generation of element matrices using symbolic manipulations.

Development of Path Tracking Control Algorithm for a 4 DOF Spatial Manipulator Using PID Controller

2020 ◽  
pp. 433-445
Author(s):  
Pradeep Reddy Bonikila ◽  
Ravi Kumar Mandava ◽  
Pandu Ranga Vundavilli
Keyword(s):  
Pid Controller ◽  
Dynamic Models ◽  
Control Method ◽  
Robotic Manipulator ◽  
Industrial Applications ◽  
Path Tracking ◽  
End Effector ◽  
Straight Line ◽  
Feedback Control Method ◽  
Manipulator Arm

The path tracking phenomenon of a robotic manipulator arm plays an important role, when the manipulators are used in continuous path industrial applications, such as welding, machining and painting etc. Nowadays, robotic manipulators are extensively used in performing the said tasks in industry. Therefore, it is essential for the manipulator end effector to track the path designed to perform the task in an effective way. In this chapter, an attempt is made to develop a feedback control method for a 4-DOF spatial manipulator to track a path with the help of a PID controller. In order to design the said controller, the kinematic and dynamic models of the robotic manipulator are derived. Further, the concept of inverse kinematics has been used to track different paths, namely a straight line and parabolic paths continuously. The effectiveness of the developed algorithm is tested on a four degree of freedom manipulator arm in simulations.

A Finite Element Formulation of a Flexible Slider Crank Mechanism Using Local Coordinates

1995 ◽  
Vol 117 (3) ◽  
pp. 329-335 ◽  
Author(s):  
Behrooz Fallahi ◽  
S. Lai ◽  
C. Venkat
Keyword(s):  
Rigid Body ◽  
Coordinate System ◽  
Displacement Vector ◽  
Lagrange Equation ◽  
Local Coordinate System ◽  
Body Motion ◽  
Elastic Displacement ◽  
Global Coordinate System ◽  
Element Formulation ◽  
Crank Mechanism

The need for higher manufacturing throughput has lead to the design of machines operating at higher speeds. At higher speeds, the rigid body assumption is no longer valid and the links should be considered flexible. In this work, a method based on the Modified Lagrange Equation for modeling a flexible slider-crank mechanism is presented. This method possesses the characteristic of not requiring the transformation from the local coordinate system to the global coordinate system. An approach using the homogeneous coordinate for element matrices generation is also presented. This approach leads to a formalism in which the displacement vector is expressed as a product of two matrices and a vector. The first matrix is a function of rigid body motion. The second matrix is a function of rigid body configuration. The vector is a function of the elastic displacement. This formal separation helps to facilitate the generation of element matrices using symbolic manipulators.

scholarly journals GPS-Free Localization Algorithm for Wireless Sensor Networks

Sensors ◽  
2010 ◽  
Vol 10 (6) ◽  
pp. 5899-5926 ◽  
Author(s):  
Lei Wang ◽  
Qingzheng Xu
Keyword(s):  
Wireless Sensor Networks ◽  
Sensor Networks ◽  
Coordinate System ◽  
Probability Model ◽  
Local Coordinate System ◽  
Convergence Time ◽  
Wireless Sensor ◽  
Global Coordinate System ◽  
Multiplication Factor ◽  
Localization Scheme

Localization is one of the most fundamental problems in wireless sensor networks, since the locations of the sensor nodes are critical to both network operations and most application level tasks. A GPS-free localization scheme for wireless sensor networks is presented in this paper. First, we develop a standardized clustering-based approach for the local coordinate system formation wherein a multiplication factor is introduced to regulate the number of master and slave nodes and the degree of connectivity among master nodes. Second, using homogeneous coordinates, we derive a transformation matrix between two Cartesian coordinate systems to efficiently merge them into a global coordinate system and effectively overcome the flip ambiguity problem. The algorithm operates asynchronously without a centralized controller; and does not require that the location of the sensors be known a priori. A set of parameter-setting guidelines for the proposed algorithm is derived based on a probability model and the energy requirements are also investigated. A simulation analysis on a specific numerical example is conducted to validate the mathematical analytical results. We also compare the performance of the proposed algorithm under a variety multiplication factor, node density and node communication radius scenario. Experiments show that our algorithm outperforms existing mechanisms in terms of accuracy and convergence time.

Modelling time-dependent mechanical behaviour of softwood using deformation kinetics

Holzforschung ◽  
2011 ◽  
Vol 65 (2) ◽  
Author(s):  
Emil Tang Engelund ◽  
Staffan Svensson
Keyword(s):  
Coordinate System ◽  
Mechanical Behaviour ◽  
Local Coordinate System ◽  
Microfibril Angle ◽  
Significant Degree ◽  
Local System ◽  
Time Dependent ◽  
Global Coordinate System ◽  
Time Dependent Behaviour ◽  
Dependent Behaviour

Abstract The time-dependent mechanical behaviour (TDMB) of softwood is relevant, e.g., when wood is used as building material where the mechanical properties must be predicted for decades ahead. The established mathematical models should be able to predict the time-dependent behaviour. However, these models are not always based on the actual physical processes causing time-dependent behaviour and the physical interpretation of their input parameters is difficult. The present study describes the TDMB of a softwood tissue and its individual tracheids. A model is constructed with a local coordinate system that follows the microfibril orientation in the S2 layer of the cell wall. The inclination of the local system to the global coordinate system reflects the microfibril angle of the tracheid. Normal excitations in the local system perform linear elastically, whereas shearing excitation in the local system produces both elastic and inelastic responses. The results of the model are compared with experimental results of different types. It was observed that the model is able to describe the results. Moreover, to some surprise, the introduction of only elastic and viscous properties on the microscopic scale leads to an apparent macroscopic viscoelasticity, i.e., the time-dependent processes are to a significant degree reversible.

Instantaneous Kinematics of Parallel-Chain Robotic Mechanisms

1992 ◽  
Vol 114 (3) ◽  
pp. 349-358 ◽  
Author(s):  
V. Kumar
Keyword(s):  
Inverse Kinematics ◽  
Robotic Manipulators ◽  
Parallel Manipulators ◽  
Parallel Structure ◽  
End Effector ◽  
Serial Manipulators ◽  
Parallel Scheme ◽  
Parallel Chain ◽  
Manipulation System ◽  
Dual Arm

This paper addresses the instantaneous kinematics of robotic manipulators which have an in-parallel scheme of actuation. Hybrid geometries which require both serial and parallel actuation are also considered. Multifingered grippers, walking vehicles, and multiarm manipulation systems in addition to robot arms with a parallel structure can be included in this broad category. The direct and inverse kinematics (and statics) of these devices is discussed with particular attention to applications in control. An analytical method based on screw system theory for obtaining transformation equations between joint and end-effector coordinates is described. Special configurations in which the end-effector gains or loses a degree of freedom, which are also known as geometric singularities, are an important consideration in this study. This is because the number of special configurations or singularities in the workspace is far more for in-parallel manipulators than that for serial manipulators. The special configurations for a planar dual-arm manipulation system, which can be kinematically modeled as a 5-R linkage, are discussed in some detail as an example.

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