scholarly journals A discrete path/trajectory planner for robotic arms

1989 ◽  
Vol 31 (1) ◽  
pp. 1-28 ◽  
Author(s):  
H. H. Tan ◽  
R. B. Potts
Keyword(s):  
Degrees Of Freedom ◽  
Minimum Cost ◽  
Challenging Problem ◽  
Final State ◽  
End Effector ◽  
Joint Torques ◽  
Robotic Arms ◽  
Joint Coordinates ◽  
Simulation Results

AbstractAn interesting and challenging problem in robotics is the off-line determination of the minimum cost path along which an end effector should move from a given initial to a given final state. This paper presents a discrete minimum cost path/trajectory planner which provides a general solution and allows for a range of constraints such as bounds on joint coordinates, joint velocities, joint torques and joint jerks. To demonstrate the practicability and feasibility of the planner, simulation results are presented for the Stanford manipulator using three and then the full six of its degrees of freedom. Simulation runs with two-link planar arms are also presented to enable a comparison with previously published results.

Gateway Configuration for Rapid Pick-and-Place Operations of 2-Degrees-of-Freedom Parallel Robots

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Andrea Martin-Parra ◽  
David Rodriguez-Rosa ◽  
Sergio Juarez-Perez ◽  
Guillermo Rubio-Gomez ◽  
Antonio Gonzalez-Rodriguez ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Degrees Of Freedom ◽  
Jacobian Matrix ◽  
Parallel Robots ◽  
End Effector ◽  
Joint Coordinates ◽  
Pick And Place ◽  
Low Energy Consumption ◽  
Simulation Results ◽  
The Difference

Abstract This article presents a new assembling for 2 degrees-of-freedom (DOFs) parallel robots for executing rapid pick-and-place operations with low energy consumption. A conventional design of 2-DOF parallel robots is based on five-bar mechanisms. Collisions between links are highly possible, restricting the end-effector workspace and/or increasing the trajectory time to avoid collisions. In this article, an alternative assembling for preventing collisions is presented. This novel assembling allows exploring the difference between the four five-bar mechanism configurations for the same position of the end-effector. Some of these configurations yield to lower time and/or lower energy consumption for the same motorization. First, a dynamic model of the robot has been developed using matlab® and simulink® and validated by comparison with the results obtained by adams® software. A robust cascade PD regulator for controlling joint coordinates has been tuned providing a high accurate end-effector positioning. Finally, simulation results of four configurations are presented for executing controlled maneuvers. The obtained results demonstrate that the conventional configuration is the worst one in terms of trajectory time or energy consumption and, conversely, the best one corresponds to an uncommonly used configuration. A workspace map where all configurations provide faster maneuvers has been obtained in terms of Jacobian matrix and mechanism elbows distance. The results presented here allow designing a rapid manipulator for pick-and-place operations.

scholarly journals Optimization of Dynamic Task Location within a Manipulator’s Workspace for the Utilization of the Minimum Required Joint Torques

Electronics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 288
Author(s):  
Adam Wolniakowski ◽  
Charalampos Valsamos ◽  
Kanstantsin Miatliuk ◽  
Vassilis Moulianitis ◽  
Nikos Aspragathos
Keyword(s):  
High Performance ◽  
Human Robot Interaction ◽  
Optimal Position ◽  
End Effector ◽  
Joint Torques ◽  
Dynamic Task ◽  
Arbitrary Position ◽  
Simulation Results ◽  
Set Up ◽  
Task Placement

The determination of the optimal position of a robotic task within a manipulator’s workspace is crucial for the manipulator to achieve high performance regarding selected aspects of its operation. In this paper, a method for determining the optimal task placement for a serial manipulator is presented, so that the required joint torques are minimized. The task considered comprises the exercise of a given force in a given direction along a 3D path followed by the end effector. Given that many such tasks are usually conducted by human workers and as such the utilized trajectories are quite complex to model, a Human Robot Interaction (HRI) approach was chosen to define the task, where the robot is taught the task trajectory by a human operator. Furthermore, the presented method considers the singular free paths of the manipulator’s end-effector motion in the configuration space. Simulation results are utilized to set up a physical execution of the task in the optimal derived position within a UR-3 manipulator’s workspace. For reference the task is also placed at an arbitrary “bad” location in order to validate the simulation results. Experimental results verify that the positioning of the task at the optimal location derived by the presented method allows for the task execution with minimum joint torques as opposed to the arbitrary position.

An Emergency Tracking Controller Design for a Manipulator After its Actuator Failure

2015 ◽  
Author(s):  
Elżbieta Jarzębowska ◽  
Adam Szewczyk
Keyword(s):  
Degrees Of Freedom ◽  
Controller Design ◽  
Actuator Failure ◽  
End Effector ◽  
Model Based ◽  
Rest Position ◽  
Control Goal ◽  
Tracking Controllers ◽  
Tracking Controller ◽  
Simulation Results

This paper presents a development of two model-based emergency tracking controllers which can be turned on when one of actuators of a system fails during motion. The system is represented by a manipulator possessing 3 degrees of freedom, which may work in horizontal or vertical planes. The control goal is to enable an end effector of a broken manipulator completing tracking a predefined task as good as possible and then get back to its rest position. Simulation results confirm good performance of the designed emergency tracking controllers.

Minimum Energy Control of Redundant Cartesian Manipulators

2012 ◽  
Author(s):  
Yoram Halevi ◽  
Emanuele Carpanzano ◽  
Giuseppe Montalbano
Keyword(s):  
Degrees Of Freedom ◽  
Minimum Energy ◽  
Joint Motion ◽  
Energy Control ◽  
End Effector ◽  
Considerable Saving ◽  
Minimum Energy Control ◽  
Simulation Results ◽  
The Individual ◽  
The Cost

In redundant manipulation systems the end-effector path does not completely determine the trajectories of all the individual degrees of freedom (dof). The redundancy is used in this paper to minimize energy consumption. A full electromechanical model is used, and the invested energy is calculated explicitly. The optimization includes also displacement limits via penalty functions that are included in the cost function. The solution is based on separating the system and the input into two parts. One that is completely determined by the end-effector path and the other that is driven by it, yet free for optimization. The boundary conditions are resolved in a similar manner, where the physical values are translated to the scaled down system by using a specific projection. Simulation results show that even with limited joint motion, the redundancy can lead to a considerable saving in energy.

Analytical Determination of Principal Twists and Singular Directions in Robot Manipulators

2003 ◽  
Author(s):  
Sandipan Bandyopadhyay ◽  
Ashitava Ghosal
Keyword(s):  
Degrees Of Freedom ◽  
Riemannian Metric ◽  
Degree Of Freedom ◽  
Body Motion ◽  
Inner Product ◽  
Analytical Determination ◽  
End Effector ◽  
Singular Configurations ◽  
Analytical Expressions

The identification of principal twists of the end-effector of a manipulator undergoing multi-degree-of-freedom motion is considered to be one of the central problems in kinematics. In this paper, we use dual velocity vectors to parameterize se(3), the space of twists, and define an inner product of two dual velocities as a dual number analog of a Riemannian metric on SE(3). We show that the principal twists can be obtained from the solution of an eigenvalue problem associated with this dual metric. It is shown that the computation of principal twists for any degree-of-freedom (DoF) of rigid-body motion, requires the solution of at most a cubic dual characteristic equation. Furthermore, the special nature of the coefficients yields simple analytical expressions for the roots of the dual cubic, and this in turn leads to compact analytical expressions for the principle twists. We also show that the method of computation allows us to separately identify the rotational and translational degrees-of-freedom lost or gained at singular configurations. The theory is applicable to serial, parallel, and hybrid manipulators, and is illustrated by obtaining the principal twists and singular directions for a 3-DoF parallel, and a hybrid 6-DoF manipulator.

Minimum Energy Control of Redundant Manipulators With Axes Coupling and Compounded Path

2014 ◽  
Author(s):  
Lior Alpert ◽  
Yoram Halevi
Keyword(s):  
Energy Consumption ◽  
Degrees Of Freedom ◽  
Minimum Energy ◽  
Joint Motion ◽  
Redundant Manipulators ◽  
End Effector ◽  
Minimum Energy Control ◽  
Optimization Simulation ◽  
Simulation Results ◽  
The Individual

In redundant manipulation systems the end-effector path does not completely determine the trajectories of all the individual degrees of freedom and this freedom can be used to enhance the performance in some sense. The paper deals with utilizing the redundancy to minimize energy consumption. It extends previous results by considering more general cases of possible coupling between the axes, e.g. three axes for planar motion, and more general paths comprising of several primitive motions connected dynamically. The solution is based on projections into lower subspaces that separate the system and the input into two parts. One that is completely determined by the end-effector path and the other that is free for optimization. Simulation results show that redundancy, even with limited joint motion, can lead to a considerable reduction in energy consumption.

Stiffness Design for a Spatial Three Degrees of Freedom Serial Compliant Manipulator Based on Impact Configuration Decomposition

2012 ◽  
Vol 5 (1) ◽  
Author(s):  
Dongming Gan ◽  
Nikos G. Tsagarakis ◽  
Jian S. Dai ◽  
Darwin G. Caldwell ◽  
Lakmal Seneviratne
Keyword(s):  
Degrees Of Freedom ◽  
General Procedure ◽  
Joint Torque ◽  
End Effector ◽  
Joint Torques ◽  
Serial Manipulators ◽  
Stiffness Design ◽  
Compliant Joint ◽  
The Impact ◽  
Three Degrees Of Freedom

This paper proposes a method of stiffness design for a spatial Three Degrees of Freedom (3DOF) serial compliant manipulator with the objective of protecting the compliant joint actuators when the manipulator comes up against impact. System dynamic equations of serial compliant manipulators integrated with an impact model are linearized to identify the maximum joint torques in the impact. Based on this, a general procedure is given in which maximum joint torques are calculated with different directions of end-effector velocity and impact normal in the manipulator workspace based on a given magnitude of end-effector velocity. By tuning the stiffness for each compliant joint to ensure the maximum joint torque does not exceed the maximum value of the actuator, candidate stiffness values are obtained to make the compliant actuators safe in all cases. The theory and procedure are then applied to the spatial 3DOF serial compliant manipulator of which the impact configuration is decomposed into a 2DOF planar serial manipulator and a 1DOF manipulator with a 2DOF link based on the linearized impact-dynamic model. Candidate stiffness of the 3DOF serial compliant manipulator is obtained by combining analysis of the 2DOF and 1DOF manipulators. The method introduced in this paper can be used for both planar and spatial compliant serial manipulators.

AN INTERVAL ANALYSIS METHOD FOR WRENCH WORKSPACE DETERMINATION OF PARALLEL MANIPULATOR ARCHITECTURES

2016 ◽  
Vol 40 (2) ◽  
pp. 139-154 ◽  
Author(s):  
Joshua K. Pickard ◽  
Juan A. Carretero
Keyword(s):  
Interval Analysis ◽  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Parallel Manipulators ◽  
Design Parameters ◽  
End Effector ◽  
Interval Analysis Method ◽  
Reachable Workspace ◽  
Manipulator Design

This paper deals with the wrench workspace (WW) determination of parallel manipulators. The WW is the set of end-effector poses (positions and orientations) for which the active joints are able to balance a set of external wrenches acting at the end-effector. The determination of the WW is important when selecting an appropriate manipulator design since the size and shape of the WW are dependent on the manipulator’s geometry (design) and selected actuators. Algorithms for the determination of the reachable workspace and the WW are presented. The algorithms are applicable to manipulator architectures utilizing actuators with positive and negative limits on the force/torque they can generate, as well as cable-driven parallel manipulator architectures which require nonnegative actuator limits to maintain positive cable tensions. The developed algorithms are demonstrated in case studies applied to a cable-driven parallel manipulator with 2-degrees-of-freedom and three cables and to a 3-RRR parallel manipulator. The approaches used in this paper provide guaranteed results and are based on methods utilizing interval analysis techniques for the representation of end-effector poses and design parameters.

scholarly journals Optimization of Joint Torques of Robot Using Dynamic Redundant Degrees of Freedom.

1992 ◽  
Vol 10 (5) ◽  
pp. 682-688
Author(s):  
Tamio ARAI ◽  
Shih-Hsuan CHIU ◽  
Akira SAIKI ◽  
Hisashi OSUMI
Keyword(s):  
Degrees Of Freedom ◽  
Joint Torques

scholarly journals Finite-Horizon Kinetic Energy Optimization of a Redundant Space Manipulator

2021 ◽  
Vol 11 (5) ◽  
pp. 2346
Author(s):  
Alessandro Tringali ◽  
Silvio Cocuzza
Keyword(s):  
Kinetic Energy ◽  
Real Time ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Computational Time ◽  
Redundant Manipulators ◽  
Space Robotics ◽  
Optimal Method ◽  
End Effector ◽  
Global Optimal

The minimization of energy consumption is of the utmost importance in space robotics. For redundant manipulators tracking a desired end-effector trajectory, most of the proposed solutions are based on locally optimal inverse kinematics methods. On the one hand, these methods are suitable for real-time implementation; nevertheless, on the other hand, they often provide solutions quite far from the globally optimal one and, moreover, are prone to singularities. In this paper, a novel inverse kinematics method for redundant manipulators is presented, which overcomes the above mentioned issues and is suitable for real-time implementation. The proposed method is based on the optimization of the kinetic energy integral on a limited subset of future end-effector path points, making the manipulator joints to move in the direction of minimum kinetic energy. The proposed method is tested by simulation of a three degrees of freedom (DOF) planar manipulator in a number of test cases, and its performance is compared to the classical pseudoinverse solution and to a global optimal method. The proposed method outperforms the pseudoinverse-based one and proves to be able to avoid singularities. Furthermore, it provides a solution very close to the global optimal one with a much lower computational time, which is compatible for real-time implementation.

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