scholarly journals New Sensor Device to Accurately Measure Cable Tension in Cable-Driven Parallel Robots

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3604
Author(s):  
Guillermo Rubio-Gómez ◽  
Sergio Juárez-Pérez ◽  
Antonio Gonzalez-Rodríguez ◽  
David Rodríguez-Rosa ◽  
Lis Corral-Gómez ◽  
...  
Keyword(s):  
Parallel Robots ◽  
Control Algorithms ◽  
Cable Tension ◽  
End Effector ◽  
New Device ◽  
Fixed Frame ◽  
Serial Robots ◽  
Sensor Device ◽  
Wide Range ◽  
Improved Accuracy

Cable-driven parallel robots are a special type of robot in which an end-effector is attached to a fixed frame by means of several cables. The position and orientation of the end-effector can be controlled by controlling the length of the cables. These robots present a wide range of advantages, and the control algorithms required have greater complexity than those in traditional serial robots. Measuring the cable tension is an important task in this type of robot as many control algorithms rely on this information. There are several well-known approaches to measure cable tension in cable robots, where a trade-off between complexity and accuracy is observed. This work presents a new device based on strain gauges to measure cable tension specially designed to be applied in cable-driven parallel robots. This device can be easily mounted on the cable near the fixed frame, allowing the cable length and orientation to change freely, while the measure is taken before the cable passes through the guiding pulleys for improved accuracy. The results obtained from the device show a strong repeatability and linearity of the measures

scholarly journals Dexterous Grasping Tasks Generated With an Add-on End Effector of a Haptic Feedback System

2016 ◽  
Vol 16 (3) ◽  
Author(s):  
Jean-Claude Leon ◽  
Thomas Dupeux ◽  
Jean-Rémy Chardonnet ◽  
Jérôme Perret
Keyword(s):  
Force Feedback ◽  
Haptic Feedback ◽  
Feedback System ◽  
Validation Process ◽  
End Effector ◽  
New Device ◽  
Virtual Hand ◽  
Wide Range ◽  
Hand Exoskeleton ◽  
Technical Solutions

The simulation of grasping operations in virtual reality (VR) is required for many applications, especially in the domain of industrial product design, but it is very difficult to achieve without any haptic feedback. Force feedback on the fingers can be provided by a hand exoskeleton, but such a device is very complex, invasive, and costly. In this paper, we present a new device, called HaptiHand, which provides position and force input as well as haptic output for four fingers in a noninvasive way, and is mounted on a standard force-feedback arm. The device incorporates four independent modules, one for each finger, inside an ergonomic shape, allowing the user to generate a wide range of virtual hand configurations to grasp naturally an object. It is also possible to reconfigure the virtual finger positions when holding an object. The paper explains how the device is used to control a virtual hand in order to perform dexterous grasping operations. The structure of the HaptiHand is described through the major technical solutions required and tests of key functions serve as validation process for some key requirements. Also, an effective grasping task illustrates some capabilities of the HaptiHand.

scholarly journals A Fuzzy Sliding Mode Controller for Planar 4-Cable Direct Driven Robot

Enfoque UTE ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 99-109
Author(s):  
Xavier Iván Aguas ◽  
Andrés Cuaycal ◽  
Israel Paredes ◽  
Marco Herrera
Keyword(s):  
Sliding Mode ◽  
Single Point ◽  
Kinematic Model ◽  
Parallel Robots ◽  
Sliding Mode Controller ◽  
End Effector ◽  
Wide Range ◽  
Potential Applications ◽  
Fuzzy Sliding Mode ◽  
Movement Simulation

Cable Direct Driven Robots (CDDRs) are a special class of parallel robots but they are formed by replacing all the supporting rigid links with cables. Compare with traditional robots, these robots are good candidates for performing a wide range of potential applications. A Planar CDDR model is considered in this paper since no rotational move and no moment resistance are required on the end-effector, all 4 cables convene in a single point and the end-effector is modeled as a point mass. The main goal of this paper is to present a new approach in control by developing a Sliding Mode Controller (SMC) with a Fuzzy-PI as sliding surface using Fuzzy logic toolbox in Matlab/Simulink. The tests performed were Step change reference test and Tracking trajectory test to observe the behavior of the cables during the trajectory and the end-effector movement. Simulation was carried out on Planar 4-Cable CDDR to prove the effectiveness of the proposed control law and the results were compared with a PI Controller and a conventional SMC in terms of integral square error (ISE) index. Only the kinematic model of Planar 4-Cable CDDR is considered in this paper.

Self-Forcing Mechanism of the Braided Tube as a Robotic Gripper

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
Zufeng Shang ◽  
Jiayao Ma ◽  
Jinhua Li ◽  
Zemin Zhang ◽  
Guokai Zhang ◽  
...  
Keyword(s):  
The Self ◽  
Design Parameters ◽  
Robot Arm ◽  
End Effector ◽  
Detailed Understanding ◽  
New Device ◽  
Cylindrical Object ◽  
Object Weight ◽  
Wide Range ◽  
Different Shapes

Robotic grippers, which act as the end effector and contact the objects directly, play a crucial role in the performance of the robots. In this paper, we design and analyze a new robotic gripper based on the braided tube. Apart from deployability, a self-forcing mechanism, i.e., the holding force increases with load/object weight, facilitates the braided tube as a robotic gripper to grasp objects with different shapes, weights, and rigidities. First, taking a cylindrical object as an example, the self-forcing mechanism is theoretically analyzed, and explicit formulas are derived to estimate the holding force. Second, experimental and numerical analyses are also conducted for a more detailed understanding of the mechanism. The results show that a holding force increment by 120% is achieved due to self-forcing, and the effects of design parameters on the holding force are obtained. Finally, a braided gripper is fabricated and operated on a KUKA robot arm, which successfully grasps a family of objects with varying shapes, weights, and rigidities. To summarize, the new device shows great potentials for a wide range of engineering applications where properties of the objects are varied and unpredictable.

scholarly journals Wrench-Feasible Workspace of Mobile Cable-Driven Parallel Robots

2020 ◽  
Vol 12 (3) ◽  
Author(s):  
Tahir Rasheed ◽  
Philip Long ◽  
Stéphane Caro
Keyword(s):  
Convex Hull ◽  
Case Studies ◽  
High Speed ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Static Equilibrium ◽  
Equilibrium Conditions ◽  
Cable Tension ◽  
End Effector ◽  
Novel Concept

Abstract Cable-driven parallel robots (CDPRs) hold numerous advantages over conventional parallel robots in terms of high speed and large workspace. Cable-driven parallel robots whose workspace can be further increased by the modification of their geometric architecture are known as reconfigurable cable-driven parallel robots. A novel concept of reconfigurable cable-driven parallel robots that consists of a classical cable-driven parallel robot mounted on multiple mobile bases is known as mobile CDPR. This paper proposes a methodology to trace the wrench-feasible workspace of mobile cable-driven parallel robots by determining its available wrench set. Contrary to classical cable-driven parallel robots, we show that the available wrench set of a mobile cable-driven parallel robot depends, not only on the cable tension limits but also on the static equilibrium conditions of the mobile bases. The available wrench set is constructed by two different approaches known as convex hull approach and hyperplane shifting method. Three case studies are carried out for the validation of the proposed methodology. The proposed approach is experimentally validated on a mobile cable-driven parallel robot with a point-mass end-effector and two mobile bases.

A step identification method of joint parameters of robots based on the measured pose of end-effector

2015 ◽  
Vol 229 (17) ◽  
pp. 3218-3233 ◽  
Author(s):  
Lijin Fang ◽  
Pengfei Dang
Keyword(s):  
Optimization Problem ◽  
Particle Swarm Optimization Algorithm ◽  
Kinematic Model ◽  
Identification Problem ◽  
Parallel Robots ◽  
Identification Accuracy ◽  
End Effector ◽  
Identification Method ◽  
Serial Robots ◽  
Joint Parameters

According to the measured pose error of end-effector, a step identification method of joint parameters based on quantum-behaved particle swarm optimization algorithm is proposed to improve the accuracy of robots. Due to the nonlinear characteristic of kinematic model of robots, the identification problem of joint parameters is regarded as a nonlinear optimization problem, and solved through the two-step identification. Firstly, the joint parameters are individually optimized in the convergence order, and the prior converged joint parameter is substituted into optimization model to continue iteration until all of the joint parameters are converged. And secondly, the joint parameters are further optimized simultaneously in the searching space around previous converged values to finish the kinematic identification. The simulation results illustrate that not only the identification accuracy, but the identification efficiency can be improved by adopting this method. Furthermore, the step identification method of joint parameters is feasible for both serial robots and parallel robots.

scholarly journals Dynamic and Oscillatory Motions of Cable-Driven Parallel Robots Based on a Nonlinear Cable Tension Model

2017 ◽  
Vol 9 (6) ◽  
Author(s):  
Sana Baklouti ◽  
Eric Courteille ◽  
Stéphane Caro ◽  
Mohamed Dkhil
Keyword(s):  
Dynamic Response ◽  
Dynamic Modeling ◽  
Dynamic Modulus ◽  
Mechanical Analysis ◽  
Parallel Robots ◽  
Original Formulation ◽  
Cable Tension ◽  
End Effector ◽  
Numerical Investigations ◽  
Softening Behavior

In this paper, dynamic modeling of cable-driven parallel robots (CDPRs) is addressed where each cable length is subjected to variations during operation. It is focusing on an original formulation of cable tension, which reveals a softening behavior when strains become large. The dynamic modulus of cable elasticity is experimentally identified through dynamic mechanical analysis (DMA). Numerical investigations carried out on suspended CDPRs with different sizes show the effect of the proposed tension formulation on the dynamic response of the end-effector.

scholarly journals Dynamic and Wrench-Feasible Workspace Analysis of a Cable-Driven Parallel Robot Considering a Nonlinear Cable Tension Model

2021 ◽  
Vol 12 (1) ◽  
pp. 244
Author(s):  
Vu N. D. Kieu ◽  
Shyh-Chour Huang
Keyword(s):  
Parallel Robot ◽  
Mechanical Analysis ◽  
Industrial Applications ◽  
Parallel Robots ◽  
Kinematic Equation ◽  
Cable Tension ◽  
End Effector ◽  
Tension Distribution ◽  
Workspace Analysis ◽  
High Dynamics

Cable-driven parallel robots (CDPRs) have several advantages and have been widely used in many industrial fields, especially industrial applications that require high dynamics, high payload capacity, and a large workspace. In this study, a design model for a CDPR system was proposed, and kinematic and dynamic modeling of the system was performed. Experiments were carried out to identify the dynamic modulus of elastic cables based on the dynamic mechanical analysis (DMA) method. A modified kinematic equation considering cable nonlinear tension was developed to determine the optimal cable tension at each position of the end-effector, and the wrench-feasible workspace was analyzed at various motion accelerations. The simulation results show that the proposed CDPR system obtains a large workspace, and the overall workspace is satisfactory and unrestricted for moving ranges in directions limited by the X-axis and the Y-axis from −0.3 to 0.3 m and by the Z-axis from 0.1 to 0.7 m. The overall workspace was found to depend on the condition of acceleration as well as the moving ranges limited by the end-effector. With an increase in external acceleration, the cable tension distribution increased and reached a maximum in the case of 100 m/s2.

The Kinetostatic Conditioning of Two-Limb Schönflies Motion Generators

2008 ◽  
Vol 1 (1) ◽  
Author(s):  
Jean-François Gauthier ◽  
Jorge Angeles ◽  
Scott B. Nokleby ◽  
Alexei Morozov
Keyword(s):  
Characteristic Length ◽  
Kinematic Chain ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Substantial Part ◽  
Robot Arm ◽  
End Effector ◽  
Serial Robots ◽  
Fixed Orientation ◽  
Schönflies Motion

This paper introduces a study on the kinetostatic conditioning of two-limb Schönflies motion generators. These are robots capable of producing the motions undergone by the end-effector of what is known as selective-compliance assembly robot arm (SCARA) systems, which can best be described as the motions of the tray of a waiter: three independent translations plus one rotation about an axis of fixed orientation. SCARA systems are usually understood as four-axis serial robots, Schönflies motion generators being a generalization thereof, that encompass first and foremost parallel architectures. Kinetostatic conditioning is understood here in connection with the condition number of each of the two Jacobian matrices of the parallel robot under study. After a brief introduction on the geometry and the kinematics of two-limb parallel systems, the kinetostatics of this class of robots is discussed; whence, the calculation of the kinetostatic conditioning of these robots is undertaken. The motivation behind this work is the need to understand an unstable behavior of the prototype in a substantial part of its workspace, which is attributed to poor conditioning. A main result of this paper is the correlation between the shortest dimension of the robot kinematic chain and the characteristic length, which hints to the need of specifying the range of the characteristic length when optimizing the dimensions of robots of the class studied here, a result that may equally hold for parallel robots in general.

Nonlinear solution of the reaction–diffusion equation using a two-step third–fourth-derivative block method

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Oluwaseun Adeyeye ◽  
Ali Aldalbahi ◽  
Jawad Raza ◽  
Zurni Omar ◽  
Mostafizur Rahaman ◽  
...  
Keyword(s):  
Diffusion Equation ◽  
Reaction Diffusion ◽  
Numerical Approach ◽  
Reaction Diffusion Equations ◽  
Reaction Diffusion Equation ◽  
Block Method ◽  
Wide Range ◽  
Higher Derivatives ◽  
Fourth Derivative ◽  
Improved Accuracy

AbstractThe processes of diffusion and reaction play essential roles in numerous system dynamics. Consequently, the solutions of reaction–diffusion equations have gained much attention because of not only their occurrence in many fields of science but also the existence of important properties and information in the solutions. However, despite the wide range of numerical methods explored for approximating solutions, the adoption of block methods is yet to be investigated. Hence, this article introduces a new two-step third–fourth-derivative block method as a numerical approach to solve the reaction–diffusion equation. In order to ensure improved accuracy, the method introduces the concept of nonlinearity in the solution of the linear model through the presence of higher derivatives. The method obtained accurate solutions for the model at varying values of the dimensionless diffusion parameter and saturation parameter. Furthermore, the solutions are also in good agreement with previous solutions by existing authors.

scholarly journals Smallest Maximum Cable Tension Determination for Cable-Driven Parallel Robots

2021 ◽  
pp. 1-20
Author(s):  
Hussein Hussein ◽  
Joao Cavalcanti Santos ◽  
Jean-Baptiste Izard ◽  
Marc Gouttefarde
Keyword(s):  
Parallel Robots ◽  
Cable Tension
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