Robust Visual Control of Parallel Robots under Uncertain Camera Orientation

Trujano, Miguel A.; Garrido, R.; Soria, Alberto

doi:10.5772/51743

Cited by 8 publications

(7 citation statements)

References 49 publications

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“…The parallel mechanism experimental platform (as depicted in Figure 3) can be employed to validate the trajectory tracking accuracy performance. 49,50…”

Section: Simulations and Experimentsmentioning

confidence: 99%

Non-singular terminal sliding mode control for redundantly actuated parallel mechanism

Zhang

Fang

Zou

2020

International Journal of Advanced Robotic Systems

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In this article, the trajectory tracking control is developed by implementing a non-singular terminal sliding mode control for the redundantly actuated parallel mechanism system. The proposed control scheme could guarantee that the tracking errors converge to zero asymptotically. The problem of singularity with regard to conventional terminal sliding mode control scheme can be eliminated with the presented novel non-singular terminal sliding mode surface as well. The corresponding stability of the proposed control scheme has also been proved theoretically in terms of Lyapunov method. In addition, simulations and experiments are conducted for trajectory tracking to validate the effectiveness of the proposed scheme. The illustrative results demonstrate that the proposed scheme is available to solve the uncertainties and external disturbances with self-tuning in real time. Furthermore, the prominent characteristics of the presented control scheme are quick convergence, high accuracy, and high robustness, which can achieve excellent tracking performance as compared with computed torque control scheme and conventional sliding mode control scheme.

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“…The parallel mechanism experimental platform (as depicted in Figure 3) can be employed to validate the trajectory tracking accuracy performance. 49,50…”

Section: Simulations and Experimentsmentioning

confidence: 99%

Non-singular terminal sliding mode control for redundantly actuated parallel mechanism

Zhang

Fang

Zou

2020

International Journal of Advanced Robotic Systems

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“…The most common approach consists of the direct observation of the end-effector pose [6,7,8]. However, some applications prevent the observation of the end-effector of a parallel mechanism by vision [9,10,11,12]. For instance, it is not wise to imagine observing the end-effector of a machine-tool while it is generally not a problem to observe its legs that are most often designed with slim and rectilinear rods [2].…”

Section: Introductionmentioning

confidence: 99%

Minimal representation for the control of parallel robots via leg observation considering a hidden robot model

Briot¹,

Rosenzveig²,

Martinet

et al. 2016

Mechanism and Machine Theory

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Previous works on the visual servoing of parallel robots using the observation of their leg directions validated the feasibility of the approach but they have enlighten two main surprising results for which no answer was given: (i) the observed robot which is composed of n legs could be controlled in most cases using the observation of only m leg directions (m < n), and that (ii) in some cases, the robot did not converge to the desired end-effector pose, even if the observed leg directions did (i.e. there was not a global diffeomorphism between the observation space and the robot space). Recently, it was shown that the visual servoing of the leg directions of the Gough-Stewart platform and the Adept Quattro with 3 translational degrees of freedom was equivalent to controlling other virtual robots that have assembly modes and singular configurations different from those of the real ones. These hidden robot models are tangible visualizations of the mapping between the observation space and the real robots Cartesian space. Thanks to this concept, all the aforementioned points were answered for the mentioned robots. In this paper, the concept of hidden robot model is generalized for any type of parallel robots controlled using visual servos based on the observation of the leg directions. It is shown that the concept of hidden robot model is a powerful tool that gives useful insights about the visual servoing of robots using leg direction observation. With the concept of hidden robot model, the singularity problem of the controller can be addressed and the convergence issues of the controller can be explained, understood and solved. All these results are validated in simulations and through experiments on a Quattro robot.

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“…Planar parallel robots are widely used in various industrial applications and, for this reason, they have attracted increasing attention of many researchers. [20][21][22] Clearly, it is crucial to analyze their singularities. Within this scope, Sefrioui and Gosselin 23 studied the graphical representation of singularity contours in the workspace.…”

Section: Introductionmentioning

confidence: 99%

Singularity analysis of two-legged planar parallel robots with three degrees of freedom

Özdemir

2016

Proceedings of the Institution of Mechanical Engineers, Part C:

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Planar two-legged parallel robots with three degrees of freedom have been suggested in the literature as a solution to reduce the leg interference problem of their conventional three-legged counterparts, and since then have attracted considerable attention. This paper presents a singularity analysis of these robots. Three alternatives, namely the robots with 2-RRR, 2-RPR, and 2-PRR structures are considered. Type I, II, and III singularity conditions are obtained taking into account all possible actuation schemes. Several singularity-free actuation schemes are enumerated and discussed. The performed analysis also shows that adjustable designs are possible for manipulators with 2-PRR structures to have singularity-free operation. The proposed design concept and its effectiveness are illustrated through numerical examples.

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Robust Visual Control of Parallel Robots under Uncertain Camera Orientation

Cited by 8 publications

References 49 publications

Non-singular terminal sliding mode control for redundantly actuated parallel mechanism

Non-singular terminal sliding mode control for redundantly actuated parallel mechanism

Minimal representation for the control of parallel robots via leg observation considering a hidden robot model

Singularity analysis of two-legged planar parallel robots with three degrees of freedom

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