Stability of haptic systems with fractional order controllers

Tokatlı, Ozan; Patoğlu, Volkan

doi:10.1109/iros.2015.7353518

Cited by 11 publications

(7 citation statements)

References 31 publications

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“…respectively, where ω is the frequency [5], [20], [21]. The admittance matching approach used in [5] utilizes these relations to find an IOAC that matches the admittance of a given FOAC for a frequency of interest ω 0 , e.g., the operating frequency of the drill ω 0 = 34 Hz.…”

Section: A Controller Parametersmentioning

confidence: 99%

A Variable-Fractional Order Admittance Controller for pHRI

Sirintuna

Aydın

Çaldıran

et al. 2020

2020 IEEE International Conference on Robotics and Automation (ICRA)

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In today's automation driven manufacturing environments, emerging technologies like cobots (collaborative robots) and augmented reality interfaces can help integrating humans into the production workflow to benefit from their adaptability and cognitive skills. In such settings, humans are expected to work with robots side by side and physically interact with them. However, the trade-off between stability and transparency is a core challenge in the presence of physical human robot interaction (pHRI). While stability is of utmost importance for safety, transparency is required for fully exploiting the precision and ability of robots in handling labor intensive tasks. In this work, we propose a new variable admittance controller based on fractional order control to handle this tradeoff more effectively. We compared the performance of fractional order variable admittance controller with a classical admittance controller with fixed parameters as a baseline and an integer order variable admittance controller during a realistic drilling task. Our comparisons indicate that the proposed controller led to a more transparent interaction compared to the other controllers without sacrificing the stability. We also demonstrate a use case for an augmented reality (AR) headset which can augment human sensory capabilities for reaching a certain drilling depth otherwise not possible without changing the role of the robot as the decision maker.

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Section: A Controller Parametersmentioning

confidence: 99%

A Variable-Fractional Order Admittance Controller for pHRI

Sirintuna

Aydın

Çaldıran

et al. 2020

2020 IEEE International Conference on Robotics and Automation (ICRA)

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“…Among many application areas, fractional order calculus has been utilized in modeling of viscoelastic materials and for motion control of robotic systems. An impedance controller using fractional order calculus for haptic rendering of virtual walls can be found in [10]. In this study, the Grunwald-Letnikov formulation is used for calculation of fractional order derivative/integral (differintegral) since this formulation allows easier implementation of the differintegral in discrete time domain [11].…”

Section: A Fractional Order Controlmentioning

confidence: 99%

Fractional order admittance control for physical human-robot interaction

Aydın

Tokatlı

Patoğlu

et al. 2017

2017 IEEE World Haptics Conference (WHC)

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Abstract-In physical human-robot interaction (pHRI), the cognitive skill of a human is combined with the accuracy, repeatability and strength of a robot. While the promises and potential outcomes of pHRI are glamorous, the control of such coupled systems is challenging in many aspects. In this paper, we propose a new controller, fractional order admittance controller, for pHRI systems. The stability analysis of the new control system with human in-the-loop is performed and the interaction performance is investigated experimentally with 10 subjects during a task imitating a contact with a stiff environment. The results show that the fractional order controller is more robust than the standard admittance controller and helps to reduce the human effort in task execution.

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“…Haptic interfaces are desired to remain stable as they inevitably work in conjunction with a human operator. Stability of uniform-rate controllers has been studied extensively in the literature [2,[7][8][9][10][11][12]; as opposed to this, multi-rate controllers have received very limited attention [3][4][5]. Gil et al [7], for instance, performed stability analysis of a 1-DoF haptic device by direct application of Routh's criterion.…”

Section: Introductionmentioning

confidence: 99%

“…This work was later extended by Hulin et al in [8] to consider the effect of the human operator and by Gil et al in [9] to study the effect of time delay and physical damping on stability, respectively. In [10] stability analysis of fractional-order haptic controllers was presented. Mashayekhi et al [11] carried out stability analysis using frequency response function analysis; and more recently, the same group used Lyapunov-Krazuvskii functional approach in [12].…”

Section: Introductionmentioning

confidence: 99%

Stability Analysis of a Dual-Rate Haptics Controller Using Discrete-Time Root-Locus Method

Ganiny

Koul

Ahmad

2021

Lecture Notes in Mechanical Engineering

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In this paper, the classical discrete-time root-locus method is extended for analyzing the stability of a dual-rate haptics controller. The given controller involves two closed-loop feedback gains, damping and stiffness (of the virtual wall), implemented at different sampling rates. Owing to the multi-variable and multi-rate nature of such controllers, analyzing their stability by the direct application of the root-locus method is not feasible. At the outset, the characteristic equation of the controller is thereby set up in a suitable mathematical form amenable to the rootlocus analysis. Thereafter the analysis is carried out by sequentially considering the damping and stiffness as feedback gains. Besides helping in establishing the stability bounds readily, the classical discrete-time root-locus method provides qualitative information about the stability contours of the dual-rate haptics controller.

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Stability of haptic systems with fractional order controllers

Cited by 11 publications

References 31 publications

A Variable-Fractional Order Admittance Controller for pHRI

A Variable-Fractional Order Admittance Controller for pHRI

Fractional order admittance control for physical human-robot interaction

Stability Analysis of a Dual-Rate Haptics Controller Using Discrete-Time Root-Locus Method

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