O. Altuzarra, O. Salgado, V. Petuya and A. Hernández
This paper aims to provide tools for the complete Jacobian analysis of robotic manipulators of general topology, using a comprehensive velocity equation.
Abstract
Purpose
This paper aims to provide tools for the complete Jacobian analysis of robotic manipulators of general topology, using a comprehensive velocity equation.
Design/methodology/approach
First, a modelling process is made in order to build the velocity equation using simple constraint equations: i.e. length restriction, relative motion and rigid body constraints. Then the motion space is solved, i.e. the space that spans all feasible motions of the manipulator.
Findings
The velocity equation is comprehensive, i.e. it relates all kinematic variables, not only input and output. The Jacobian related to the comprehensive velocity equation is a square dimensionless matrix. This characteristic has great importance when evaluating manipulability or closeness to singularities. Employing the motion space, any kinematic entity can be studied: i.e. velocities and accelerations of any active/passive joints, screw axis, axodes, and so on. Also a comprehensive singularity analysis can be made.
Research limitations/implications
The approach presented is focused on the kinetostatic analysis of manipulators and, therefore, subjected to rigid body assumption.
Practical implications
The paper presents a proposal of effective codes for engineering analysis of manipulators.
Originality/value
This approach is based on a pure computational kinematic analysis that unifies all kinetostatic analysis for any manipulator topology (i.e. serial, parallel, hybrid manipulators, complex mechanisms, redundant‐or non‐redundant‐actuated). The characteristic Jacobian matrix is dimensionless and provides the means for a complete singularity analysis and an effective use of indicators.
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Keywords
Alfonso Hernández, Oscar Altuzarra, Oscar Salgado, Charles Pinto and Víctor Petuya
The purpose of this paper is to present a step‐by‐step methodology for the design of parallel kinematic machines (PKMs), from the initial stages of the conceptual definition of a…
Abstract
Purpose
The purpose of this paper is to present a step‐by‐step methodology for the design of parallel kinematic machines (PKMs), from the initial stages of the conceptual definition of a new machine to an optimum design fulfilling the complete set of design requirements.
Design/methodology/approach
The methodology includes consideration of the kinematic, static and dynamic features required for the manipulator, which must all be assessed in complete industrial design. It is applied to a 4‐degrees‐of‐freedom (DOF) Schönflies motion generator for pick & place operations by way of example.
Findings
The authors specify the key stages of a detailed design procedure for parallel manipulators.
Originality/value
There are many publications on the development of specific robots and parallel manipulators based on their particular characteristics. However, it is relatively rare to find a paper on the general procedure with a step‐by‐step methodology applicable to any parallel manipulator.
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Oscar Salgado, Oscar Altuzarra, Fernando Viadero and Alfonso Hernández
The purpose of this paper is to provide a general approach to compute, determine, and characterize the connectivity of the end‐effector of a robotic manipulator of arbitrary…
Abstract
Purpose
The purpose of this paper is to provide a general approach to compute, determine, and characterize the connectivity of the end‐effector of a robotic manipulator of arbitrary architecture, in any of the postures that it can reach.
Design/methodology/approach
The types of motion of this link, i.e. translational, screw motions, combinations thereof, and self‐motions, are first defined and determined, simplifying the understanding of the instantaneous behaviour of the manipulator, aided by the definition of an alternative input basis.
Findings
The characterization provided by this paper simplifies the understanding of the instantaneous behaviour of the manipulator. The mobility of the end‐effector is completely characterized by the principal screws of its motion, which can be obtained from a generalized eigenproblem. In the process, alternative demonstrations of well‐known properties of the principal screws are provided.
Research limitations/implications
The approach presented is focused on the kinetostatic analysis of manipulators, and therefore, subjected to rigid body assumption.
Practical implications
This paper proposes effective approaches for engineering analysis of robotic manipulators.
Originality/value
This approach is based on a pure theoretical kinematic analysis that can characterize computationally the motion that the end‐effector of an industrial robot of general morphology (i.e. serial, parallel, hybrid manipulators, complex mechanisms, redundant or non‐redundantly actuated). Also, being implemented on a general‐purpose software for the kinematic analysis of mechanisms, it provides visual information of the motion capabilities of the manipulator, highly valuable on its design stages.
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Mingzhe Tao, Jinghua Xu, Shuyou Zhang and Jianrong Tan
This work aims to provide a rapid robust optimization design solution for parallel robots or mechanisms, thereby circumventing inefficiencies and wastage caused by empirical…
Abstract
Purpose
This work aims to provide a rapid robust optimization design solution for parallel robots or mechanisms, thereby circumventing inefficiencies and wastage caused by empirical design, as well as numerous physical verifications, which can be employed for creating high-quality prototypes of parallel robots in a variety of applications.
Design/methodology/approach
A novel subregional meta-heuristic iteration (SMI) method is proposed for the optimization of parallel robots. Multiple subregional optimization objectives are established and optimization is achieved through the utilisation of an enhanced meta-heuristic optimization algorithm, which roughly employs chaotic mapping in the initialization strategy to augment the diversity of the initial solution. The non-dominated sorting method is utilised for updating strategies, thereby achieving multi-objective optimization.
Findings
The actuator error under the same trajectory is visibly reduced after SMI, with a maximum reduction of 6.81% and an average reduction of 1.46%. Meanwhile, the response speed, maximum bearing capacity and stiffness of the mechanism are enhanced by 63.83, 43.98 and 97.51%, respectively. The optimized mechanism is more robust and the optimization process is efficient.
Originality/value
The proposed robustness multi-objective optimization via SMI is more effective in improving the performance and precision of the parallel mechanisms in various applications. Furthermore, it provides a solution for the rapid and high-quality optimization design of parallel robots.