Resolving Hyper-Redundant Planar Serial Robots to Ensure Grasp

Hyper-redundant snakelike serial robots are of great interest due to their application in search and rescue during disaster relief in highly cluttered environments and recently in the field of medical robotics. A key feature of these robots is the presence of a large number of redundant actuated joints and the associated well-known challenge of motion planning. This problem is even more acute in the presence of obstacles. Obstacle avoidance for point bodies, nonredundant serial robots with a few links and joints, and wheeled mobile robots has been extensively studied, and several mature implementations are available. However, obstacle avoidance for hyper-redundant snakelike robots and other extended articulated bodies is less studied and is still evolving. This paper presents a novel optimization algorithm, derived using calculus of variation, for the motion planning of a hyper-redundant robot where the motion of one end (head) is an arbitrary desired path. The algorithm computes the motion of all the joints in the hyper-redundant robot in a way such that all its links avoid all obstacles present in the environment. The algorithm is purely geometric in nature, and it is shown that the motion in free space and in the vicinity of obstacles appears to be more natural. The paper presents the general theoretical development and numerical simulations results. It also presents validating results from experiments with a 12-degree-of-freedom (DOF) planar hyper-redundant robot moving in a known obstacle field.

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Force Capabilities of Two-Degree-of-Freedom Serial Robots Equipped With Passive Isotropic Force Limiters

Volume 5B: 39th Mechanisms and Robotics Conference ◽

10.1115/detc2015-46486 ◽

2015 ◽

Author(s):

Meiying Zhang ◽

Thierry Laliberté ◽

Clément Gosselin

Keyword(s):

Human Robot Interaction ◽

Contact Forces ◽

Degree Of Freedom ◽

Practical Implementation ◽

Robot Interaction ◽

End Effector ◽

Serial Robots ◽

Serial Robot ◽

Maximum Contact ◽

Two Degree Of Freedom

This paper proposes the use of passive force and torque limiting devices to bound the maximum forces that can be applied at the end-effector or along the links of a robot, thereby ensuring the safety of human-robot interaction. Planar isotropic force limiting modules are proposed and used to analyze the force capabilities of a two-degree-of-freedom planar serial robot. The force capabilities at the end-effector are first analyzed. It is shown that, using isotropic force limiting modules, the performance to safety index remains excellent for all configurations of the robot. The maximum contact forces along the links of the robot are then analyzed. Force and torque limiters are distributed along the structure of the robot in order to ensure that the forces applied at any point of contact along the links are bounded. A power analysis is then presented in order to support the results. Finally, examples of mechanical designs of force/torque limiters are shown to illustrate a possible practical implementation of the concept.

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On Force and Motion Control of Serial-Parallel Robots

Volume 2B: 24th Biennial Mechanisms Conference ◽

10.1115/96-detc/mech-1151 ◽

1996 ◽

Author(s):

Shih-Liang Wang

Keyword(s):

Control Algorithm ◽

Virtual Work ◽

Parallel Robot ◽

Parallel Robots ◽

Joint Torque ◽

Compact Structure ◽

Serial Robots ◽

S Matrix ◽

Serial Robot ◽

Rate Control Algorithm

Abstract A serial-parallel robot has the high stiffness and accuracy of a parallel robot, and a large workspace and compact structure of a serial robot. In this paper, the resolved force control algorithm is derived for serial-parallel robots, including a 3-articulated-arm platform robot, a linkage robot, and two cooperating serial robots. A S matrix is derived to relate joint torque to the external load. Using the principle of virtual work, S is used in resolved rate control algorithm to relate the tool velocity to joint rate. S can be easily expanded to the control of redundant actuation, and it can be used to interpret singularity. MATLAB is used to verify these control algorithms with graphical motion animation.

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Reliability-Based Analysis and Optimization of the Gravity Balancing Performance of Spring-Articulated Serial Robots with Uncertainties

Journal of Mechanisms and Robotics ◽

10.1115/1.4053048 ◽

2021 ◽

pp. 1-32

Author(s):

Vu Linh Nguyen ◽

Chin-Hsing Kuo ◽

Po Ting Lin

Keyword(s):

Pso Algorithm ◽

Reliability Based Design Optimization ◽

Swarm Optimization ◽

Reliability Based Design ◽

Serial Robots ◽

Simulation Based ◽

Serial Robot ◽

Simulation Results ◽

Uncertainty Level

Abstract This article proposes a method for analyzing the gravity balancing reliability of spring-articulated serial robots with uncertainties. Gravity balancing reliability is defined as the probability that the torque reduction ratio (the ratio of the balanced torque to the unbalanced torque) is less than a specified threshold. The reliability analysis is performed by exploiting a Monte Carlo simulation (MCS) with consideration of the uncertainties in the link dimensions, masses, and compliance parameters. The gravity balancing begins with a simulation-based analysis of the gravitational torques of a typical serial robot. Based on the simulation results, a gravity balancing design for the robot using mechanical springs is realized. A reliability-based design optimization (RBDO) method is also developed to seek a reliable and robust design for maximized balancing performance under a prescribed uncertainty level. The RBDO is formulated with consideration of a probabilistic reliability constraint and solved by using a particle swarm optimization (PSO) algorithm. A numerical example is provided to illustrate the gravity balancing performance and reliability of a robot with uncertainties. A sensitivity analysis of the balancing design is also performed. Lastly, the effectiveness of the RBDO method is demonstrated through a case study in which the balancing performance and reliability of a robot with uncertainties are improved with the proposed method.

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Novel use of the Monte-Carlo methods to visualize singularity configurations in serial manipulators

JOURNAL OF MECHANICAL ENGINEERING AND SCIENCES ◽

10.15282/jmes.15.2.2021.02.0627 ◽

2021 ◽

Vol 15 (2) ◽

pp. 7948-7963

Author(s):

Mohamed Aboelnasr ◽

Hussein M Bahaa ◽

Ossama Mokhiamar

Keyword(s):

Monte Carlo ◽

Numerical Methods ◽

Curve Fitting ◽

Jacobian Matrix ◽

Forward Kinematics ◽

Graphical Methods ◽

Kinematic Singularity ◽

Serial Manipulators ◽

Serial Robots ◽

Contour Plots

This paper analyses the problem of the kinematic singularity of 6 DOF serial robots by extending the use of Monte-Carlo numerical methods to visualize singularity configurations. To achieve this goal, first, forward kinematics and D-H parameters have been derived for the manipulator. Second, the derived equations are used to generate and visualize a workspace that gives a good intuition of the motion shape of the manipulator. Third, the Jacobian matrix is computed using graphical methods, aiming to locate positions that cause singularity. Finally, the data obtained are processed in order to visualize the singularity and to design a trajectory free of singularity. MATLAB robotics toolbox, Symbolic toolbox, and curve fitting toolbox are the MATLAB toolboxes used in the calculations. The results of the surface and contour plots of the determinate of the Jacobian matrix behavior lead to design a manipulator’s trajectory free of singularity and show the parameters that affect the manipulator’s singularity and its behavior in the workspace.

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Extended Mobility Carried Out with a Double Hexapod Robot

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.166-167.271 ◽

2010 ◽

Vol 166-167 ◽

pp. 271-276 ◽

Cited By ~ 1

Author(s):

Mihai Margaritescu ◽

Ana Maria Eulampia Ivan ◽

Vlad Vaduva ◽

Cornel Brisan

Keyword(s):

Fast Response ◽

High Accuracy ◽

Positioning System ◽

Hexapod Robot ◽

Parallel Kinematics ◽

High Stiffness ◽

Serial Robots ◽

Visual Comparison ◽

Operating Space

The double hexapod robot consists in two staged hexapod platforms – Stewart Gough platforms - combining in a certain measure the advantages of the robots with parallel kinematics and of the serial robots: high accuracy, high stiffness, fast response and small dimensions, having an extended operating space. Different modelling and construction aspects were described in few previous articles. Some examples of trajectories generated with this positioning system are now presented to illustrate its mobility, as well as the workspaces for one and two hexapods in order to make possible a visual comparison between the two volumes.

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Forward kinematic analysis of Dobot using closed-loop method

IAES International Journal of Robotics and Automation (IJRA) ◽

10.11591/ijra.v9i3.pp153-159 ◽

2020 ◽

Vol 9 (3) ◽

pp. 153

Author(s):

Javier Dario Sanjuan De Caro ◽

Mohammad Rahman ◽

Ivan Rulik

Keyword(s):

Analytical Solution ◽

Kinematic Analysis ◽

Closed Loop ◽

Dynamical Model ◽

Forward Kinematics ◽

Loop Method ◽

Serial Robots ◽

Forward Kinematic

Dobot is a hybrid robot that combines features from parallel and serial robots. Because of this characteristic, the robot excels for is reliability, allowing its implementation in diverse applications. Therefore, researchers have studied its kinematics to improve its capabilities. However, to the extent of our knowledge, no analysis has been reported taking into consideration the closed-loop configuration of Dobot. Thus, this article presents the complete analytical solution for the forward kinematics of Dobot, considering each link. The results are expected to be utilized in the development of a dynamical model that contemplates the dynamics of each element of the robot.

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Influence of the Manufacturing Accuracy of the Planetary Cycloid Gear on the Positioning Accuracy of the Parallel Robot

Proceedings of Higher Educational Institutions Маchine Building ◽

10.18698/0536-1044-2021-11-13-21 ◽

2021 ◽

pp. 13-21

Author(s):

S.V. Palochkin ◽

Y.V. Sinitsyna ◽

K.G. Erastova

Keyword(s):

High Speed ◽

Printed Circuit Boards ◽

Parallel Robot ◽

Circuit Boards ◽

Positioning Accuracy ◽

Printed Circuit ◽

Serial Robots ◽

Sequential Structure ◽

Robot Positioning ◽

Manufacturing Accuracy

The increased accuracy in high-speed positioning of the parallel robot effector in comparison with that of serial robots with a sequential structure is often the main reason for their use in various modern industries, such as the manufacture of printed circuit boards for microelectronics. However, despite the higher theoretical positioning accuracy, due to the kinematic structure of the parallel robot, in practice this characteristic largely depends on the accuracy of manufacturing individual elements of this mechanism, the most important of which are the gearboxes of the drives of its input pairs. A solution to the urgent problem of determining the effect of the manufacturing accuracy of planetary pinion gearboxes included in the drive of a five-link parallel robot on the positioning accuracy of its output link is proposed. A specific relationship has been determined between the grade of accuracy number of the gear part dimensions and the robot positioning accuracy. The unevenness of the positioning accuracy along the coordinate axes of its working area is revealed. It was found that near the area of certain robot positions the accuracy of its positioning drops sharply.

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