Grasp Quality Evaluation in Underactuated and Compliant Robotic Hands: New Indexes and New Challenges

The new trend in the design of robotic hands is to make them underactuated and compliant, so that they can safely interact with the enviroment, and adapt to the objects they have to grasp.
Evaluating the grasping capabilities of such type of hands is a challenging task because there is the need of an evaluation method that takes into account i) which forces can be actually controlled by the hand, depending on its actuation system, and ii) the parameters that characterize the contact points such as the friction coefficient and the maximum and minimum applicable contact forces.
To this aim, the work presented in [1] revisits some traditional quality measures developed for multi-fingered, fully actuated hands, and applies them to the case of underactuated hands. Measures based on the wrench space computation, namely the largest minimum resisted wrench, and measures of contact and grasp robustness, namely the Potential Grasp Robustness (PGR) and the Potential Contact Robustness (PCR), are compared through simulated examples. Both types of indexes are found to be suitable for evaluating underactuated grasps in a realistic and coherent way, because they can account for friction constraints and physically achievable contact forces.
Underactuated and compliant hands can adapt to the shape of the objects they have to grasp and tend to perform power grasps, rather than precision grasps. This consideration lead to the work described in [2], where authors demonstrate that the PGR can be applied not only to precision grasps, but also to power grasps.
The workshop entitled “Evaluation and benchmarking of underactuated and soft robotic hands” was held at IROS 2016 to discuss on the possibility of having a common benchmarking framework for assessing the quality of compliant and underactuated manipulation systems, and highlighted that in the community there is a clear need of comparability and reproducibility, not only for soft and underactuated hands, but for general robotic grasping systems.
The posters and the slides that were presented at the workshop are available here.



[1] M. Pozzi, A. M. Sundaram, M. Malvezzi, D. Prattichizzo, and M. A. Roa, “Grasp quality evaluation in underactuated robotic hands,” in Proceedings, IEEE/RSJ International Conference on Intelligent Robots and Systems, 2016. [PDF]

[2] M. Pozzi, M. Malvezzi, and D. Prattichizzo, “On grasp quality measures: Grasp robustness and contact force distribution in underactuated and compliant robotic hands,” IEEE Robotics and Automation Letters, vol. 2, 2017. [Link]

A new perspective paper published on Frontiers on Neurorobotics

A human-robot interaction perspective on assistive and rehabilitation robotics

Philipp Beckerle, Gionata Salvietti, Ramazan Unal, Domenico Prattichizzo, Simone Rossi, Claudio Castellini, Sandra Hirche, Satoshi Endo, Heni Ben Amor, Matei Ciocarlie, Fulvio Mastrogiovanni, Brenna D. Argall and Matteo Bianchi

Abstract Assistive and rehabilitation devices are a promising and challenging field of recent robotics research. Motivated by societal needs such as aging populations, such devices can support motor functionality and subject training. The design, control, sensing and assessment of the devices become more sophisticated due to a human in the loop. This paper gives a human-robot interaction perspective on current issues and opportunities in the field. On the topic of control and machine learning, approaches that support but do not distract subjects are reviewed.  Options to provide sensory user-feedback that are currently missing from robotic devices are outlined. Parallels between device acceptance and affective computing are made. Furthermore, requirements for functional assessment protocols that relate to real-world tasks are discussed. In all topic areas, the design of human-oriented frameworks and methods is dominated by challenges related to the close interaction between the human and robotic device. This paper discusses the aforementioned aspects in order to open up new perspectives for future robotic solutions.
A human-robot interaction perspective on assistive and rehabilitation robotics. Available from:

Our paper on wearable haptics for Augmented reality is the most popular article in IEEE Transactions on Haptics

Screenshot from 2017-05-19 15-21-58


Wearable Haptic Systems for the Fingertip and the Hand: Taxonomy, Review, and Perspectives

Our group has just published a new survey article on the IEEE Transactions on Haptics!

The 23-pages-long manuscript presents a taxonomy and review of wearable haptic systems for the fingertip and the hand, focusing on those systems directly addressing wearability challenges. We also discuss the main technological and design challenges for the development of wearable haptic interfaces, and report on the future perspectives of the field.

This work is the result of a collaboration between my group SIRSLab, the CNRS at Irisa and Inria Rennes (C. Pacchierotti), UPMC (V. Hayward), Inria Chile (S. Sinclair), and SSSA (A. Frisoli and M. Solazzi), in the framework of project WEARHAP.


C. Pacchierotti, S. Sinclair, M. Solazzi, A. Frisoli, V. Hayward, D. Prattichizzo. “Wearable Haptic Systems for the Fingertip and the Hand: Taxonomy, Review, and Perspectives.” IEEE Transactions on Haptics, 2017.

The paper is available from IEEEXplore (Open Access!):

New paper on Transaction on Neural System and Rehabilitation Engineering

While attending at the Consortium Meeting of the EU project SoftPro, we are happy to announce our new paper on the Robotic Sixth Finger appeared in Transaction on Neural System and Rehabilitation Engineering. The paper is part of the Special Issue on Wearable Robotics for Motion Assistance and Rehabilitation.

Compensating Hand Function in Chronic Stroke Patients Through the Robotic Sixth Finger  

G. Salvietti, I. Hussain, D. Cioncoloni, S. Taddei, S. Rossi, D. Prattichizzo

A novel solution to compensate hand grasping abilities is proposed for chronic stroke patients. The goal is to provide the patients with a wearable robotic extra-finger that can be worn on the paretic forearm by means of an elastic band. The proposed prototype, the Robotic Sixth Finger, is a modular articulated device that can adapt its structure to the grasped object shape. The extra-finger and the paretic hand act like the two parts of a gripper cooperatively holding an object. We evaluated the feasibility of the approach with four chronic stroke patients performing a qualitative test, the Frenchay Arm Test. In this proof of concept study, the use of the Robotic Sixth Finger has increased the total score of the patients of 2 points in a 5 points scale. The subjects were able to perform the two grasping tasks included in the test that were not possible without the robotic extra-finger. Adding a robotic opposing finger is a very promising approach that can significantly improve the functional compensation of the chronic stroke patient during everyday life activities.


Paper bibtex file:

Author = {Salvietti, G. and Hussain, I. and Cioncoloni, D. and Taddei, S. and Rossi, S. and Prattichizzo, D.},
Title = {Compensating Hand Function in Chronic Stroke Patients Through the Robotic Sixth Finger},
Journal = {Transaction on Neural System and Rehabilitation Engineering},
Volume = {25},
Number = {2},
Pages = {142–150},
Year = {2017}

New paper “Steering and control of miniaturized untethered soft magnetic grippers with haptic assistance” on IEEE T-ASE

A new paper has been published on the IEEE Transactions on Automation Science and Engineering (IF 2.7).

C. Pacchierotti, F. Ongaro, F. van den Brink, C. Yoon, D. Prattichizzo, D.H. Gracias, S. Misra. “Steering and control of miniaturized untethered soft magnetic grippers with haptic assistance”. IEEE Transactions on Automation Science and Engineering. In Press, 2017.


The work is a collaboration between our lab, the Surgical Robotics Lab at the University of Twente, and the Gracias Laboratory at the Johns Hopkins University.

Full paper: and


Talk (screencast of IROS2016) on Cooperative aerial tele-manipulation with haptic feedback

This is the screencast of the talk that Domenico Prattichizzo gave in IEEE IROS 2016 in Korea to present the IROS paper:

M. Mohammadi, A. Franchi, Davide Barcelli, and D. Prattichizzo,
“Cooperative aerial tele-manipulation with haptic feedback”,
2016 IEEE/RSJ International Conference on Intelligent Robots and Systems(IROS), Daejeon, Korea, 2016, pp. 5092-5098.

Summary of the paper: In this paper, we propose a bilateral tele-operation scheme for cooperative aerial manipulation in which a human operator drives a team of Vertical Take-Off and Landing (VTOL) aerial vehicles, that grasped an object beforehand, and receives a force feedback depending on the states of the system.

In this paper, we propose a bilateral tele-operation scheme for cooperative aerial manipulation in which a human operator drives a team of Vertical Take-Off and Landing (VTOL) aerial vehicles, that grasped an object beforehand, and receives a force feedback depending on the states of the system. For application scenarios in which dexterous manipulation by each robot is not necessary, we propose using a rigid tool at- tached to the vehicle through a passive spherical joint, equipped with a simple adhesive mechanism at the tool-tip that can stick to the grasped object. Having more than two robots, we use the extra degrees of freedom to find the optimal force allocation in term of minimum power and forces smoothness. The human operator commands a desired trajectory for the robot team through a haptic interface to a pose controller, and the output of the pose controller along with system constraints, e.g., VTOL limited forces and contact maintenance, defines the feasible set of forces. Then, an on-line optimization allocates forces by minimizing a cost function of forces and their variation. Finally, propeller thrusts are computed by a dedicated attitude and thrust controller in a decentralized fashion. Human/Hardware in the loop simulation study shows efficiency of the proposed scheme, and the importance of haptic feedback to achieve a better performance.


Check out the video on youtube:

The paper is here linked