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Multilateral teleoperation over communication time delay using the time-domain passivity approach (2019)
Journal Article
Ryu, J., Ha-Van, Q., & Jafari, A. (in press). Multilateral teleoperation over communication time delay using the time-domain passivity approach. IEEE Transactions on Control Systems Technology, https://doi.org/10.1109/TCST.2019.2948126

A general framework to stabilize multilateral teleoperation system over a communication time delay based on the well-known time-domain passivity approach (TDPA) is proposed. The uniqueness of this framework is that it is independent of the amount of... Read More about Multilateral teleoperation over communication time delay using the time-domain passivity approach.

Enhancing the rate-hardness of haptic interaction: Successive force augmentation approach (2019)
Journal Article
Singh, H., Janetzko, D., Jafari, A., Weber, B., Lee, C. I., & Ryu, J. H. (2020). Enhancing the rate-hardness of haptic interaction: Successive force augmentation approach. IEEE Transactions on Industrial Electronics, 67(1), 809-819. https://doi.org/10.1109/TIE.2019.2918500

© 1982-2012 IEEE. There have been numerous approaches that have been proposed to enlarge the impedance range of haptic interaction while maintaining stability. However, enhancing the rate-hardness of haptic interaction while maintaining stability is... Read More about Enhancing the rate-hardness of haptic interaction: Successive force augmentation approach.

Enhancing the force transparency of time domain passivity approach: Observer-based gradient controller (2019)
Presentation / Conference
Singh, H., Jafari, A., & Ryu, J. (2019, May). Enhancing the force transparency of time domain passivity approach: Observer-based gradient controller. Paper presented at The 2019 International Conference on Robotics and Automation (ICRA)

Passivity has been the most often used constraint for the stable controller design of bilateral teleoperation systems. Especially, Time Domain Passivity Approach (TDPA) has been used in many applications since it has been known as one of the least co... Read More about Enhancing the force transparency of time domain passivity approach: Observer-based gradient controller.

Enhancing the Command-Following Bandwidth for Transparent Bilateral Teleoperation (2018)
Journal Article
Singh, H., Jafari, A., Ryu, J. H., & Peer, A. (2018). Enhancing the Command-Following Bandwidth for Transparent Bilateral Teleoperation. Proceedings of the ... IEEE/RSJ International Conference on Intelligent Robots and Systems. IEEE/RSJ International Conference on Intelligent Robots and Systems, 4972-4979. https://doi.org/10.1109/IROS.2018.8593866

© 2018 IEEE. Enhancing transparency of a teleoperation system by increasing the command-following bandwidth has not received lots of attention so far. This is considered a challenging task since in a teleoperation system the command-following bandwid... Read More about Enhancing the Command-Following Bandwidth for Transparent Bilateral Teleoperation.

Lyapunov observer/controller for stable haptic interaction (2018)
Conference Proceeding
Jafari, A., Singh, H., Karunanayaka, H., Ryu, J. H., Chong, J., & Etoundi, A. (2018). Lyapunov observer/controller for stable haptic interaction. https://doi.org/10.1109/AIM.2018.8452311

© 2018 IEEE. Passivity has been the most common tool to achieve stability in haptic and teleoperation systems; however passivity-based approaches suffer from the conservativism of passivity criteria. Therefore, it is essential to have an approach whi... Read More about Lyapunov observer/controller for stable haptic interaction.

Modelling of a Bio-Inspired Knee Joint and Design of an Energy Saving Exoskeleton Based on Performance Maps Optimisation for Condylar Knee Prosthetics (2018)
Conference Proceeding
Etoundi, A., Chong, J., & Jafari, A. (2018). Modelling of a Bio-Inspired Knee Joint and Design of an Energy Saving Exoskeleton Based on Performance Maps Optimisation for Condylar Knee Prosthetics. https://doi.org/10.1109/CoDIT.2018.8394776

© 2018 IEEE. The process of designing bio-inspired knee joint for prosthetics/exoskeletons has been a challenging issue due to the complicated relationships between the performance criteria and the link lengths of the design space, or workspace in th... Read More about Modelling of a Bio-Inspired Knee Joint and Design of an Energy Saving Exoskeleton Based on Performance Maps Optimisation for Condylar Knee Prosthetics.

Design of anatomy-based 3D patient-specific knee replacement implant model from medical imaging (2018)
Presentation / Conference
Chong, J., Matthews, J., Jafari, A., & Appolinaire, E. (2018, June). Design of anatomy-based 3D patient-specific knee replacement implant model from medical imaging. Paper presented at 2018 The 2nd International Conference on Mechanical, System and Control Engineering (ICMSC 2018)

This paper focuses on the design of an anatomy-based 3D patient-specific knee replacement implant model, which is derived from medical imaging. The investigation extracted the knee profiles from MRI scans to develop a 3D model of the knee, including... Read More about Design of anatomy-based 3D patient-specific knee replacement implant model from medical imaging.

A conceptual exoskeleton shoulder design for the assistance of upper limb movement (2018)
Journal Article
Perez, C. N., Georgilas, I., Etoundi, A., Chong, J., & Jafari, A. (2018). A conceptual exoskeleton shoulder design for the assistance of upper limb movement. Lecture Notes in Artificial Intelligence, 10965 LNAI, 291-302. https://doi.org/10.1007/978-3-319-96728-8_25

© Springer International Publishing AG, part of Springer Nature 2018. There is an increased interest on wearable technologies for rehabilitation and human augmentation. Systems focusing on the upper limbs are attempting to replicate the musculoskelet... Read More about A conceptual exoskeleton shoulder design for the assistance of upper limb movement.

Realizing low-impedance rendering in admittance-type haptic interfaces using the input-to-state stable approach (2017)
Journal Article
Nabeel, M., Jafari, A., & Ryu, J. H. (2017). Realizing low-impedance rendering in admittance-type haptic interfaces using the input-to-state stable approach. Proceedings of the ... IEEE/RSJ International Conference on Intelligent Robots and Systems. IEEE/RSJ International Conference on Intelligent Robots and Systems, 2017-September, 914-919. https://doi.org/10.1109/IROS.2017.8202254

© 2017 IEEE. This paper proposes an approach to enlarge the impedance range of admittance-type haptic interfaces. Admittance-type haptic interfaces have advantages over impedance-type haptic interfaces in the interaction with high impedance virtual e... Read More about Realizing low-impedance rendering in admittance-type haptic interfaces using the input-to-state stable approach.

The Input-to-State Stable (ISS) approach for stabilizing haptic interaction with virtual environments (2017)
Journal Article
Jafari, A., Nabeel, M., & Ryu, J. H. (2017). The Input-to-State Stable (ISS) approach for stabilizing haptic interaction with virtual environments. IEEE Transactions on Robotics, 33(4), 948-963. https://doi.org/10.1109/TRO.2017.2676127

© 2004-2012 IEEE. Passivity has been a major criterion for designing a stable haptic interface due to its numerous advantages. However, passivity-based controllers have suffered from the design conservatism of the passivity criterion, particularly wh... Read More about The Input-to-State Stable (ISS) approach for stabilizing haptic interaction with virtual environments.

Increasing the rate-hardness of haptic interaction: Successive force augmentation approach (2017)
Conference Proceeding
Singh, H., Jafari, A., & Ryu, J. (2017). Increasing the rate-hardness of haptic interaction: Successive force augmentation approach

There have been numerous approaches that have been proposed to enlarge the impedance range, however it is still a challenging issue to increase the rate-hardness of haptic interaction while maintaining stability. The actual perceived rate-hardness ha... Read More about Increasing the rate-hardness of haptic interaction: Successive force augmentation approach.

Multi degree-of-freedom successive stiffness increment approach for high stiffness haptic interaction (2016)
Presentation / Conference
Singh, H., Jafari, A., & Ryu, J. (2016, November). Multi degree-of-freedom successive stiffness increment approach for high stiffness haptic interaction. Paper presented at Asia Haptics

In haptic interaction, stability and the object’s hardness perception are of great significance. Although numerous studies have been done for stable haptic interaction, however, most of them sacrifice the actual displayed stiffness as a cost of stabi... Read More about Multi degree-of-freedom successive stiffness increment approach for high stiffness haptic interaction.

Stable and transparent teleoperation over communication time-delay: Observer-based input-to-state stable approach (2016)
Journal Article
Jafari, A., Nabeel, M., Singh, H., & Ryu, J. (2016). Stable and transparent teleoperation over communication time-delay: Observer-based input-to-state stable approach. IEEE Haptics Symposium : [proceedings]. IEEE Haptics Symposium, 2016-April, 235-240. https://doi.org/10.1109/HAPTICS.2016.7463183

In this paper, an observer-based input-to-state stable approach is proposed to stabilize teleoperation systems over communication time-delay with better transparency compared with passivity approaches. In this paper, input-to-state stable approach is... Read More about Stable and transparent teleoperation over communication time-delay: Observer-based input-to-state stable approach.

Independent force and position control for cooperating manipulators handling an unknown object and interacting with an unknown environment (2016)
Journal Article
Ryu, J. H., Jafari, A., & Jee-Hwan, R. (2016). Independent force and position control for cooperating manipulators handling an unknown object and interacting with an unknown environment. Journal of The Franklin Institute, 353(4), 857-875. https://doi.org/10.1016/j.jfranklin.2015.12.010

© 2016 The Franklin Institute. Published by Elsevier Ltd. All rights reserved. This paper presents a unified framework for system design and control in cooperative robotic systems. It introduces a highly generalized cooperative system configuration t... Read More about Independent force and position control for cooperating manipulators handling an unknown object and interacting with an unknown environment.

Increasing the impedance range of admittance-type haptic interfaces by using Time Domain Passivity Approach (2015)
Journal Article
Hwang, J. H., Nabeel, M., Lee, J., Mehmood, U., Jafari, A., & Ryu, J. H. (2015). Increasing the impedance range of admittance-type haptic interfaces by using Time Domain Passivity Approach. Proceedings of the ... IEEE/RSJ International Conference on Intelligent Robots and Systems. IEEE/RSJ International Conference on Intelligent Robots and Systems, 2015-December, 585-590. https://doi.org/10.1109/IROS.2015.7353431

© 2015 IEEE. This paper proposes a method to increase the impedance range of admittance-type haptic interfaces. Admittance-type haptic interfaces are used in various applications that typically require interaction with high impedance virtual environm... Read More about Increasing the impedance range of admittance-type haptic interfaces by using Time Domain Passivity Approach.

Stable bilateral teleoperation with input-to-state stable approach (2015)
Conference Proceeding
Jafari, A., Nabeel, M., & Ryu, J. (2015). Stable bilateral teleoperation with input-to-state stable approach

Passivity has been the most often used constraint for the controller design of bilateral teleoperation systems. However passivity has been suffering from its own design conservatism since this is a sufficient condition for stability and representing... Read More about Stable bilateral teleoperation with input-to-state stable approach.

Network formulation and stability improvement of a bilateral teleoperation system with admittance-type master interfaces (2015)
Conference Proceeding
Nabeel, M., Jafari, A., & Ryu, J. H. (2015). Network formulation and stability improvement of a bilateral teleoperation system with admittance-type master interfaces. https://doi.org/10.1109/AIM.2015.7222796

© 2015 IEEE. This paper introduces a network formulation of bilateral teleoperation systems with admittance-type master interfaces to improve their stability range with Time Domain Passivity Approach (TDPA). Since traditional network representation o... Read More about Network formulation and stability improvement of a bilateral teleoperation system with admittance-type master interfaces.

Input to state stable approach to release the conservatism of passivity-based stable haptic interaction (2015)
Journal Article
Jafari, A., & Ryu, J. (2015). Input to state stable approach to release the conservatism of passivity-based stable haptic interaction. IEEE International Conference on Robotics and Automation, https://doi.org/10.1109/ICRA.2015.7139013

Passivity has been a major criterion on designing a stable haptic interface due to many advantages. However, passivity has been suffering from its intrinsic conservatism since it only represents a small set of the whole stable region. Therefore, ther... Read More about Input to state stable approach to release the conservatism of passivity-based stable haptic interaction.

Stable admittance type haptic interaction based on time domain passivity approach (2015)
Journal Article
Jafari, A., Totorkulov, K., & Ryu, J. (2015). Stable admittance type haptic interaction based on time domain passivity approach

In this paper, we propose a stable and high transparent admittance haptic display even in free space haptic rendering. Because considering admittance haptic rendering as a one-port network is not enough to detect the active energy, new representation... Read More about Stable admittance type haptic interaction based on time domain passivity approach.

6-DOF extension of memory-based passivation approach for stable haptic interaction (2014)
Journal Article
Jafari, A., & Ryu, J. H. (2015). 6-DOF extension of memory-based passivation approach for stable haptic interaction. Intelligent Service Robotics, 8(1), 23-34. https://doi.org/10.1007/s11370-014-0161-y

© 2014, Springer-Verlag Berlin Heidelberg. This paper extends previously proposed memory-based passivity approach (MBPA) to 6 degrees-of-freedom (DOF) haptic interactions. By introducing 6-DOF virtual proxy and virtual object, connected with haptic i... Read More about 6-DOF extension of memory-based passivation approach for stable haptic interaction.


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