Singularity Free Path Planning for Parallel Robots

Lahouar, Samir; Zeghloul, S.; Romdhane, Lotfi

doi:10.1007/978-1-4020-8600-7_25

Cited by 8 publications

(8 citation statements)

References 10 publications

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“…Other works detect singular configurations during the path planning process. In (Lahouar et al, 2008) singularities of parallel robots were treated as obstacles and were avoided during path planning generation. This method was extended to cable-driven robots (Lahouar et al, 2009;Ismail et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Singularity Analysis of a Hybrid Serial-Cable Driven Planar Robot

Lahouar¹,

Romdhane²

2022

American Journal of Engineering and Applied Sciences

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In this study, we address the problem of singularities of a hybrid serial-cable driven planar robot. Based on an analytical kinetostatic analysis three types of singularities are determined, i.e., serial, parallel, and combined singularities. In addition, cable tensions should be positive, otherwise, the robot will be uncontrollable. The serial singularity corresponds to positions where the serial port of the robot is fully extended or fully folded. The parallel singularity corresponds to aligned cables and combined singularities correspond to both cases. Cable tensions distribution, within the workspace, is determined, which allowed the identification of regions where the cable tensions exceed an allowable value. The influence of physical parameters on the workspace of the robot and its singular configurations is also studied. An example of a gait rehabilitation system using this type of robot is shown. Based on the kinetostatic analysis, multi-objective optimization of the dexterity and the cable tensions is performed, which yielded solutions represented by a Pareto front. The results have been extended to the case of 3 degrees of freedom hybrid robot.

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Section: Introductionmentioning

confidence: 99%

Singularity Analysis of a Hybrid Serial-Cable Driven Planar Robot

Lahouar¹,

Romdhane²

2022

American Journal of Engineering and Applied Sciences

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“…The singularities associated with the direct kinematics of parallel manipulators (referred to as "parallel singularities" in this paper) may cause serious losses of stiffness and even control when they are approached [1]. Avoiding such singularities during motion has then drawn the interest of many researchers [2][3][4][5][6][7]. For non-redundant parallel manipulators, several strategies have been proposed to guaranty that the path to be followed by the moving platform remains sufficiently far from singular configurations [8][9].…”

Section: Introductionmentioning

confidence: 99%

Trajectory planning of kinematically redundant parallel manipulators by using multiple working modes

Ramos

Pamanes

Wenger³

2016

Mechanism and Machine Theory

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A method for joint trajectory planning of kinematically redundant parallel manipulators is presented in this paper. The method is based on the use of feasibility maps that allow the graphical assessment of postures related to the different working modes of the manipulator. Thus, in such maps suitable trajectories are found in order to improve the performance of the manipulator and to avoid parallel singularities. When the desired path cannot be achieved by using only one working mode of the manipulator without crossing parallel singularities then, by applying the approach proposed here, a number of working modes could be chosen and combined to complete the whole path. The method can be applied to parallel manipulators with one degree of kinematic redundancy, whose legs allow the changing of working modes. The efficiency of this method is shown in a case study with a 3-RRR parallel manipulator (note that this manipulator becomes kinematically redundant if the orientation of the mobile platform is not specified for a desired task), in which postures associated to four working modes are employed in such a way that parallel singularities can be avoided. The obtained joint trajectories are applied to an experimental prototype to successfully execute the desired task.

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“…The main advantage of the geometric approach is that, it establishes the nature of the boundary of the workspace [15]. A procedure to automatically generate the kinematic model of parallel mechanisms which further used for singularity free path planning is reported in [16] .…”

Section: Introductionmentioning

confidence: 99%

An Algebraic Method to Check the Singularity-Free Paths for Parallel Robots

Jha¹,

Chablat²,

Rouillier

et al. 2015

Volume 5C: 39th Mechanisms and Robotics Conference

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Trajectory planning is a critical step while programming the parallel manipulators in a robotic cell. The main problem arises when there exists a singular configuration between the two poses of the end-effectors while discretizing the path with a classical approach. This paper presents an algebraic method to check the feasibility of any given trajectories in the workspace. The solutions of the polynomial equations associated with the trajectories are projected in the joint space using Gröbner based elimination methods and the remaining equations are expressed in a parametric form where the articular variables are functions of time t unlike any numerical or discretization method. These formal computations allow to write the Jacobian of the manipulator as a function of time and to check if its determinant can vanish between two poses. Another benefit of this approach is to use a largest workspace with a more complex shape than a cube, cylinder or sphere. For the Orthoglide, a three degrees of freedom parallel robot, three different trajectories are used to illustrate this method.

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Singularity Free Path Planning for Parallel Robots

Cited by 8 publications

References 10 publications

Singularity Analysis of a Hybrid Serial-Cable Driven Planar Robot

Singularity Analysis of a Hybrid Serial-Cable Driven Planar Robot

Trajectory planning of kinematically redundant parallel manipulators by using multiple working modes

An Algebraic Method to Check the Singularity-Free Paths for Parallel Robots

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