scholarly journals Empirical Quasi-Static and Inverse Kinematics of Cable-Driven Parallel Manipulators Including Presence of Sagging

2020 ◽  
Vol 10 (15) ◽  
pp. 5318
Author(s):  
Phan Gia Luan ◽  
Nguyen Truong Thinh
Keyword(s):  
Kinematic Model ◽  
Static Problem ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
Inverse Kinematic ◽  
Inverse Kinematic Problem ◽  
Redundant Actuators ◽  
Small Change ◽  
Feasible Solutions ◽  
Flexible Cables

Cable-driven parallel manipulators (CDPMs) have been of great interest to researchers in recent years because they have many advantages compared to the traditional parallel robot. However, in many studies they lack the cable’s elasticity that leads to flexible cables just being considered as extendable rigid links. Furthermore, an external force acts on the extremities of cable and the self-weight is relevant to the length of it. Experimentally, a small change in length produces a huge change in tension act on the entire cable. By this property, the adjusting length of cable is often added to the traditional inverse kinematic solution in order to reduce the tension force exerted on the cable. This means that the load on the actuator is also reduced. Because of the relationship between tension that acts on the cable and its length, the kinematic problem itself does not make sense without concerning the static or dynamic problems. There is often interest in planning forces for actuators and the length of cables based on a given quasi-static trajectory of the moving platform. The mentioned problem is combined with the quasi-static problem with the inverse kinematic problem of CDPM. In this study, we introduce a novel procedure to produce the quasi-static model and inverse kinematic model for CDPM with the presence of sagging by using both an analytic approach and empirical approach. The produced model is time-efficient and is generalized for spatial CDPM. To illustrate the performance of the proposed model, the numerical and experimental approaches are employed to determine particular solutions in the feasible solutions set produced by our model in order to control the two redundant actuators’ CDPM tracking on a certain desired trajectory. Its results are clearly described in the experimental section.

scholarly journals Using a Cable-Driven Parallel Robot with Applications in 3D Concrete Printing

2021 ◽  
Vol 11 (2) ◽  
pp. 563
Author(s):  
Tuong Phuoc Tho ◽  
Nguyen Truong Thinh
Keyword(s):  
3D Printing ◽  
Large Scale ◽  
Trust Region ◽  
Parallel Robot ◽  
Inverse Kinematic ◽  
Programming Algorithm ◽  
Construction Time ◽  
Inverse Kinematic Problem ◽  
Robot Configuration ◽  
Printing Method

In construction, a large-scale 3D printing method for construction is used to build houses quickly, based on Computerized Aid Design. Currently, the construction industry is beginning to apply quite a lot of 3D printing technologies to create buildings that require a quick construction time and complex structures that classical methods cannot implement. In this paper, a Cable-Driven Parallel Robot (CDPR) is described for the 3D printing of concrete for building a house. The CDPR structures are designed to be suitable for 3D printing in a large workspace. A linear programming algorithm was used to quickly calculate the inverse kinematic problem with the force equilibrium condition for the moving platform; this method is suitable for the flexible configuration of a CDPR corresponding to the various spaces. Cable sagging was also analyzed by the Trust-Region-Dogleg algorithm to increase the accuracy of the inverse kinematic problem for controlling the robot to perform basic trajectory interpolation movements. The paper also covers the design and analysis of a concrete extruder for the 3D printing method. The analytical results are experimented with based on a prototype of the CDPR to evaluate the work ability and suitability of this design. The results show that this design is suitable for 3D printing in construction, with high precision and a stable trajectory printing. The robot configuration can be easily adjusted and calculated to suit the construction space, while maintaining rigidity as well as an adequate operating space. The actuators are compact, easy to disassemble and move, and capable of accommodating a wide variety of dimensions.

Clearance-Induced Position Uncertainty of Planar Linkages and Parallel Manipulators

2017 ◽  
Author(s):  
Kwun-Lon Ting ◽  
Kuan-Lun Hsu
Keyword(s):  
Kinematic Model ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Position Uncertainty ◽  
Joint Clearances ◽  
Planar Linkages ◽  
Oscillation Characteristics ◽  
Linkage Model ◽  
Input Error

The paper presents a simple and effective kinematic model and methodology, based on Ting’s N-bar rotatability laws [2629], to assess the extent of the position uncertainty caused by joint clearances for any linkage and manipulators connected with revolute or prismatic pairs. The model is derived and explained with geometric rigor based on Ting’s rotatability laws. The significant contribution includes (1) the clearance link model for P-joint that catches the translation and oscillation characteristics of the slider within the clearance and separates the geometric effect of clearance from the input error, (2) a simple uncertainty linkage model that features a deterministic instantaneous structure mounted on non-deterministic flexible legs, (3) the generality of the method, which is effective for multiloop linkages and parallel manipulators. The discussion is carried out through symmetrically constructed planar eight-bar parallel robots. It is found that the uncertainty region of a three-leg parallel robot is enclosed by a hexagon, while that of its serial counterpart is enclosed by a circle inscribed by the hexagon. A numerical example is also presented. The finding and proof, though only based on three-leg planar 8-bar parallel robots, may have a wider implication suggesting that based on kinematics, parallel robots tends to inherit more position uncertainty than their serial counterparts. The use of more loops in parallel robots cannot fully offset the adverse effect on position uncertainty caused by the use of more joints.

Kinematics, Workspace Optimization, and Performance Evaluation of a 3-Leg 6-DOF Robot in RRRS Configuration

2020 ◽  
Author(s):  
Nathan A. Jensen ◽  
Carl A. Nelson
Keyword(s):  
Performance Evaluation ◽  
Degrees Of Freedom ◽  
Experimental Validation ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
Inverse Kinematic ◽  
And Performance ◽  
Workspace Optimization ◽  
Optimization And Performance

Abstract Underactuated parallel manipulators that achieve 6 DOF via multiple controllable degrees of freedom per leg are often pursued and reported due to their large workspaces. This benefit comes at a cost to the manipulator’s performance, however. Such manipulators must then be evaluated in order to characterize their kinematics in terms of position and motion. This paper establishes a pair of inverse kinematic solutions for a previously proposed and prototyped 3-leg, 6-DOF parallel robot. These solutions are then used to define the robot’s workspace with experimental validation and to optimize the robot’s geometry for maximum workspace volume. The linear components of the Jacobian are then defined, allowing for analysis of the manipulability of the robot. The full Jacobian is also defined, and singularities are examined throughout the workspace of the robot.

An analytical and a Deep Learning model for solving the inverse kinematic problem of an industrial parallel robot

2020 ◽  
pp. 106682
Author(s):  
Juan S. Toquica ◽  
Patrícia S. Oliveira ◽  
Witenberg S.R. Souza ◽  
José Maurício S.T. Motta ◽  
Díbio L. Borges
Keyword(s):  
Deep Learning ◽  
Parallel Robot ◽  
Learning Model ◽  
Inverse Kinematic ◽  
Inverse Kinematic Problem ◽  
Deep Learning Model

scholarly journals Control of a 3-RRR Planar Parallel Robot Using Fractional Order PID Controller

2020 ◽  
Vol 17 (6) ◽  
pp. 822-836
Author(s):  
Auday Al-Mayyahi ◽  
Ammar A. Aldair ◽  
Chris Chatwin
Keyword(s):  
Fractional Order ◽  
Material Handling ◽  
State Of The Art ◽  
Kinematic Model ◽  
Parallel Robot ◽  
Inverse Kinematic ◽  
Open Loop ◽  
Parallel Robots ◽  
The State ◽  
Revolute Joints

Abstract3-RRR planar parallel robots are utilized for solving precise material-handling problems in industrial automation applications. Thus, robust and stable control is required to deliver high accuracy in comparison to the state of the art. The operation of the mechanism is achieved based on three revolute (3-RRR) joints which are geometrically designed using an open-loop spatial robotic platform. The inverse kinematic model of the system is derived and analyzed by using the geometric structure with three revolute joints. The main variables in our design are the platform base positions, the geometry of the joint angles, and links of the 3-RRR planar parallel robot. These variables are calculated based on Cayley-Menger determinants and bilateration to determine the final position of the platform when moving and placing objects. Additionally, a proposed fractional order proportional integral derivative (FOPID) is optimized using the bat optimization algorithm to control the path tracking of the center of the 3-RRR planar parallel robot. The design is compared with the state of the art and simulated using the Matlab environment to validate the effectiveness of the proposed controller. Furthermore, real-time implementation has been tested to prove that the design performance is practical.

Kinematic uncertainty analysis of a cable-driven parallel robot based on an error transfer model

2021 ◽  
pp. 1-23
Author(s):  
Jun Gao ◽  
Bin Zhou ◽  
Bin Zi ◽  
Sen Qian ◽  
Ping Zhao
Keyword(s):  
Uncertainty Analysis ◽  
Kinematic Model ◽  
Evidence Theory ◽  
Parallel Robot ◽  
Fast Response ◽  
Inverse Kinematic ◽  
Parallel Robots ◽  
Transfer Model ◽  
The Given ◽  
Error Transfer

Abstract Cable-driven parallel robots (CDPRs) are a kind of mechanism with large workspace, fast response, and low inertia. However, due to the existence of fixed pulleys, it is unavoidable to bring uncertain cable lengths and lead to pose errors of the end-effector (EE). The inverse kinematic model of a CDPR for picking up medicines is established by considering radii of fixed pulleys. The influence of radii of fixed pulleys on errors of cable lengths is explored. Error transfer model of the CPDR is constructed, and uncertain sources of cable lengths are analyzed. Based on evidence theory and error transfer model, an evidence theory-based uncertainty analysis method (ETUAM) is presented. The structural performance function for kinematic response is derived based on error transfer model. Belief and plausibility measures of joint focal elements under the given threshold are obtained. Kinematic error simulations show that errors of cable lengths become larger with the increase of radii of fixed pulleys. Compared with the vertex method and Monte Carlo method, numerical examples demonstrate the accuracy and efficiency of the ETUAM when it comes to the kinematic uncertainty analysis of the CDPR.

Redundancy Resolution of Kinematically Redundant Parallel Manipulators Via Differential Dynamic Programing

2017 ◽  
Vol 9 (4) ◽  
Author(s):  
João Cavacanti Santos ◽  
Maíra Martins da Silva
Keyword(s):  
Parallel Manipulators ◽  
Projection Methods ◽  
Inverse Kinematic ◽  
Gradient Projection ◽  
Redundancy Resolution ◽  
Inverse Kinematic Problem ◽  
Serial Manipulators ◽  
Optimal Inputs ◽  
Dynamic Programing ◽  
Gradient Projection Methods

Kinematic redundancy may be an efficient way to improve the performance of parallel manipulators. Nevertheless, the inverse kinematic problem of this kind of manipulator presents infinite solutions. The selection of a single kinematic configuration among a set of many possible ones is denoted as redundancy resolution. While several redundancy resolution strategies have been proposed for planning the motion of redundant serial manipulators, suitable proposals for parallel manipulators are seldom. Redundancy resolution can be treated as an optimization problem that can be solved locally or globally. Gradient projection methods have been successfully employed to solve it locally. For global strategies, these methods may be computationally demanding and mathematically complex. The main objective of this work is to exploit the use of differential dynamic programing (DDP) for decreasing the computational demand and mathematical complexity of a global optimization based on the gradient projection method for redundancy resolution. The outcome of the proposed method is the optimal inputs for the active joints for a given trajectory of the end-effector considering the input limitations and different cost functions. Using the proposed method, the performance of a redundant 3PRRR manipulator is investigated numerically and experimentally. The results demonstrate the capability and versatility of the strategy.

Kinematic Analysis and Singularity Loci of Spatial Four-Degree-of-Freedom Parallel Manipulators

1996 ◽  
Author(s):  
Jiegao Wang ◽  
Clément M. Gosselin
Keyword(s):  
Kinematic Analysis ◽  
Parallel Manipulators ◽  
Inverse Kinematic ◽  
Degree Of Freedom ◽  
Numerical Determination ◽  
Inverse Kinematic Problem ◽  
Flight Simulators ◽  
Important Design ◽  
Robotic Applications

Abstract The kinematic analysis and the determination of the singularity loci of spatial four-degree-of-freeedom parallel manipulators with prismatic or revolute actuators are discussed in this article. After introducing the architecture of the spatial parallel four-degree-of-freedom manipulators, algorithms for the solution of the inverse kinematic problem are provided for the two kinds of manipulators considered. Two different methods are presented for the derivation of the velocity equations and the corresponding Jacobian matrices are derived. The numerical determination of the workspace boundaries is then briefly discussed. Finally, the determination of the singularity loci is performed using the velocity equations and examples are given to illustrate the results obtained. Spatial four-degree-of-freedom parallel manipulators can be used in several robotic applications as well as in flight simulators. The determination of their singularity loci is a very important design issue.

scholarly journals NAVARO II, a Novel Scissor-Based Planar Parallel Robot1

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Damien Chablat ◽  
Luc Rolland
Keyword(s):  
Geometric Property ◽  
Kinematic Model ◽  
Parallel Robot ◽  
Inverse Kinematic ◽  
Mobile Platform ◽  
Compact Form ◽  
Revolute Joint ◽  
Actuation Mechanism ◽  
Working Space ◽  
Orthogonal Plane

This article presents a new variable actuation mechanism based on the 3-RPR parallel robot. This mechanism is an evolution of the NaVARo robot, a 3-RRR parallel robot, for which the second revolute joint of the three legs is replaced by a scissor to obtain a larger working space and avoid the use of parallelograms to operate the second revolute joint. To obtain better spatial rigidity, the leg mechanism is constructed by placing the scissors in an orthogonal plane to the plane of the manipulator displacement (3-RRR or even the 3-RPR). This geometric property brings the significant consequence of allowing the scissors to directly substitute the prismatic chains in the 3-RPR and enjoy the same kinematics advantages for the overall robots as only one solution to the inverse kinematic model. From the Jacobian expression, surfaces of singularity can be calculated and presented in a compact form. The singularity equations are presented for a robot with a similar base and mobile platform. The properties of the scissors are then determined to have a prescribed regular workspace.

Kinematic Analysis for Hybrid 2-(6-UPU) Manipulator Using Wavelet Neural Network

2014 ◽  
Vol 1016 ◽  
pp. 726-730 ◽  
Author(s):  
Arash Rahmani ◽  
Ahmad Ghanbari ◽  
Siamak Pedrammehr
Keyword(s):  
Neural Network ◽  
Parallel Manipulators ◽  
Inverse Kinematic ◽  
Wavelet Neural Network ◽  
Learning Ability ◽  
Parallel Structure ◽  
Specific Class ◽  
Inverse Kinematic Problem ◽  
Highly Nonlinear ◽  
Spiral Trajectories

This paper addresses forward and inverse kinematics of a specific class of serial-parallel manipulators, known as 2(6-UPU) manipulators. This manipulator composed of two modules which consist of elementary manipulators with the parallel structure of Stewart Platform. At first, the Kinematics Model of the hybrid manipulator is obtained. As there is a highly nonlinear relations between joint variables, and position and orientation of the end effectors, the inverse kinematic problem of these manipulators is quite complicated to solve. In this study, wavelet based neural network (WNN) with its inherent learning ability, is used to solve the inverse kinematic problem. Also, proposed wavelet neural network is applied to approximate the paths of mid and upper plates in circle and spiral trajectories. Finally, the results of simulation show high accurate performance of proposed method.

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