The influence of coordinates in robotic manipulability analysis

Lachner, Johannes; Schettino, Vincenzo; Allmendinger, Felix; Fiore, Mario D.; Ficuciello, Fanny; Siciliano, Bruno

doi:10.1016/j.mechmachtheory.2019.103722

Cited by 22 publications

(20 citation statements)

References 32 publications

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“…What is not quite often remarked from other authors is that those ellipsoids are dependent from the joint coordinate choice [3]. A change of this parametrization will lead to a different ellipsoid, meaning that any desired ellipsoid can be generated given a suitable coordinate choice.…”

Section: A Indexes For Kinematic Singularitiesmentioning

confidence: 99%

“…And if it makes sense, how can this be realized? In this work, we try to answer to these questions and we propose an approach to detect conflicts between tasks, considering a coordinate invariant measure used for the analysis of kinematic singularities of an open-chain mechanical structure already introduced in [3]. Then we give a geometrical interpretation of the detected algorithmic singularity.…”

Section: Introductionmentioning

confidence: 99%

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Geometrical Interpretation and Detection of Multiple Task Conflicts using a Coordinate Invariant Index

Schettino

Fiore

Pecorella

et al. 2020

2020 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

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Modern robots act in dynamic and partially unknown environments where path replanning can be mandatory if changes in the environment are observed. Task-prioritized control strategies are well known and effective solutions to ensure local adaptation of robot behaviour. The highest priority in a stack of tasks is typically given to the management of correct robot operation or safe interaction with the environment such as obstacles or joint limits avoidance, that we can consider as constraints. If a constraint makes impossible achieving a certain task, such as tracking a Cartesian trajectory, a local control algorithm partially sacrifices the latter which is only accomplished to the best of the robot's ability to generate internal motions. In this control framework, problems may occur in some applications, like in the surgical domain, where it is not safe that some tasks are simply sacrificed without prior notice. The contribution of this work is to introduce a coordinate invariant index, that is used to provide a geometrical interpretation of task conflicts in a task-priority control framework and to develop a method for on-line detection of algorithmic singularities, with the goal of increasing safety and performances during robot operations.

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Section: A Indexes For Kinematic Singularitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Geometrical Interpretation and Detection of Multiple Task Conflicts using a Coordinate Invariant Index

Schettino

Fiore

Pecorella

et al. 2020

2020 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

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“…Similarly to [2], also the machinery used to speed-up the computation strongly relies on the consideration of such cost function. However, joint velocity minimization has been shown to have drawbacks for robots whose joint coordinates present mixed units, which is often the case when considering robots with a large number of DOFs, e.g., mobile manipulators [30]. This aspect is also essential in the context of energy-aware motion generation [31].…”

Section: A Relevant Literaturementioning

confidence: 99%

A General Framework for Hierarchical Redundancy Resolution Under Arbitrary Constraints

Fiore¹,

Meli²,

Ziese³

et al. 2022

Preprint

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The increasing interest in autonomous robots with a high number of degrees of freedom for industrial applications and service robotics demands control algorithms to handle multiple tasks as well as hard constraints efficiently. This paper presents a general framework in which both kinematic (velocity-or acceleration-based) and dynamic (torque-based) control of redundant robots are handled in a unified fashion. The framework allows for the specification of redundancy resolution problems featuring a hierarchy of arbitrary (equality and inequality) constraints, arbitrary weighting of the control effort in the cost function and an additional input used to optimize possibly remaining redundancy. To solve such problems, a generalization of the Saturation in the Null Space (SNS) algorithm is introduced, which extends the original method according to the features required by our general control framework. Variants of the developed algorithm are presented, which ensure both efficient computation and optimality of the solution. Experiments on a KUKA LBRiiwa robotic arm, as well as simulations with a highly redundant mobile manipulator are reported.

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“…We assume that the ellipse (16) is a subset of some admissible input space U 0 ⊂ R 2 , that is, the semi-axes λ 1 = 1/ √ ρ and λ 2 = 1/ √ μ satisfy: λ 1 ≤ ω 0m and λ 2 ≤ v 0m , see (2). The positive-definite weighting matrix M allows one to account for different units of the components of input vector u 0 , [4], [29].…”

Section: A Control-input Ellipsementioning

confidence: 99%

Trailer-Maneuverability in N-Trailer Structures

Michałek

2020

IEEE Robot. Autom. Lett.

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The letter presents a trailer-maneuverability analysis for the N-trailer kinematic structures comprising a tractor and an arbitrary number of single-axle trailers equipped with steerable or fixed wheels. For an elliptically-shaped set of tractor's inputvelocities, we derive a mobility-ellipse generated in a velocity space of the (last) trailer. We show that the on-axle type of hitching present in the N-trailer leads to a singularity of a trailer-mobility (at least one degree of mobility is lost). Furthermore, we provide some relations between kinematic parameters of the N-trailer and its control inputs which enable shaping the trailer-mobility ellipse and decoupling it from a joint-configuration of the vehicle.

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The influence of coordinates in robotic manipulability analysis

Cited by 22 publications

References 32 publications

Geometrical Interpretation and Detection of Multiple Task Conflicts using a Coordinate Invariant Index

Geometrical Interpretation and Detection of Multiple Task Conflicts using a Coordinate Invariant Index

A General Framework for Hierarchical Redundancy Resolution Under Arbitrary Constraints

Trailer-Maneuverability in N-Trailer Structures

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