A variable admittance control strategy for stable physical human–robot interaction

Ferraguti, Federica; Landi, Chiara Talignani; Sabattini, Lorenzo; Bonfè, Marcello; Fantuzzi, Cesare; Secchi, Cristian

doi:10.1177/0278364919840415

Cited by 136 publications

(68 citation statements)

References 37 publications

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“…Additionally, they have experimentally shown that increasing admittance mass as well as damping contributes to the stability of the system, when instability is detected [7]. Recently, Ferraguti et al proposed an improved heuristic method for detecting the emergence of instability and a passivity-preserving inertia adaptation strategy with the use of energy tanks concept [17].…”

Section: A Related Workmentioning

confidence: 99%

“…Earlier studies in pHRI have relied on increasing the damping of the controller to increase the stability robustness of a system through energy dissipation. Some alternative approaches adapt the mass and/or the ratio between mass and damping of the controller [7], [15]- [17]. Making such alterations in the controller parameters are shown to be promising and result in better responses than an LTI interaction controller with fixed parameters.…”

Section: B Contributionsmentioning

confidence: 99%

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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 Related Workmentioning

confidence: 99%

Section: B Contributionsmentioning

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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“…The method proposed in Piwowarczyk et al ( 2020 ) uses an admittance controller to scale the force applied by the user on the robot in relation to force applied to the environment. The stability of admittance-controlled robots and their ability to cope with different environmental forces have been investigated in Ferraguti et al ( 2019 ). Admittance control was used in Li et al ( 2018 ) for an exoskeleton robot to create a reference trajectory based on measured force.…”

Section: Prior Workmentioning

confidence: 99%

Robotic Ultrasound Scanning With Real-Time Image-Based Force Adjustment: Quick Response for Enabling Physical Distancing During the COVID-19 Pandemic

et al. 2021

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During an ultrasound (US) scan, the sonographer is in close contact with the patient, which puts them at risk of COVID-19 transmission. In this paper, we propose a robot-assisted system that automatically scans tissue, increasing sonographer/patient distance and decreasing contact duration between them. This method is developed as a quick response to the COVID-19 pandemic. It considers the preferences of the sonographers in terms of how US scanning is done and can be trained quickly for different applications. Our proposed system automatically scans the tissue using a dexterous robot arm that holds US probe. The system assesses the quality of the acquired US images in real-time. This US image feedback will be used to automatically adjust the US probe contact force based on the quality of the image frame. The quality assessment algorithm is based on three US image features: correlation, compression and noise characteristics. These US image features are input to the SVM classifier, and the robot arm will adjust the US scanning force based on the SVM output. The proposed system enables the sonographer to maintain a distance from the patient because the sonographer does not have to be holding the probe and pressing against the patient's body for any prolonged time. The SVM was trained using bovine and porcine biological tissue, the system was then tested experimentally on plastisol phantom tissue. The result of the experiments shows us that our proposed quality assessment algorithm successfully maintains US image quality and is fast enough for use in a robotic control loop.

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“…In [19] the wave variable transformation was exploited to modulate the energy and improve the transparency of a teleoperation system. Regarding the energy tank, [20] proposes an impedance control with time-varying stiffness to guarantee system passivity. For admittance controlled robots, [21] exploits the tank for controlling a robotic arm for surgical application and [22] extends the method considering interactions with the environment.…”

Section: Introductionmentioning

confidence: 99%

Time-delay Compensation Using Energy Tank for Satellite Dynamics Robotic Simulators

Stefano

Vezzadini

Secchi

2019

2019 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

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In this work we present a novel approach which compensates the destabilising effects of the time delay intrinsic in the control loop of an admittance-controlled robot employed for satellite dynamics simulation. The method is based on an energy storing element, the tank, which is exploited by the controller to preserve the passivity of the system and to avoid instability. Furthermore, we compare the performance of the proposed method with existing energy-based approaches, namely time-domain-passivity and wave variable transformation. The performance comparison and robustness of the methods are analysed in a Montecarlo simulation and validated experimentally.

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A variable admittance control strategy for stable physical human–robot interaction

Cited by 136 publications

References 37 publications

A Variable-Fractional Order Admittance Controller for pHRI

A Variable-Fractional Order Admittance Controller for pHRI

Robotic Ultrasound Scanning With Real-Time Image-Based Force Adjustment: Quick Response for Enabling Physical Distancing During the COVID-19 Pandemic

Time-delay Compensation Using Energy Tank for Satellite Dynamics Robotic Simulators

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