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


New Review paper “Haptic Feedback for Microrobotics Applications: A Review” on Frontiers in Robotics and AI

A new article has been published on Frontiers in Robotics and AI.

C. Pacchierotti, S. Scheggi, D. Prattichizzo, S. Misra. “Haptic feedback for microrobotics applications: a review. Frontiers in Robotics and AI, 3(53), 2016.

Screenshot from 2016-09-05 09-15-11

Full article:

SIRSLab uses MATLAB® and Simulink® for grasp analysis of human and robotic hands

Researchers and students of SIRSLab of Univerisity of Siena use MATLAB® and Simulink® for grasp analysis of human and robotic hands.

Here’s the link to the video of Professor Prattichizzo explaining the job of our team: MathWorks Video.


mathworks 5

Paper on “THE” Project published on Physics of Life Reviews

An article summarising the results of the four years EU project “The Hand Embodied – THE “ has been published on the prestigious journal Physics of Life Reviews. Here the link to the article. As University of Siena, we have contributed to the modelling of hand synergies and we have studied a systematic way to transfer human hand skills onto robotic hands. These results can be found here.

Abstract of the paper

The term ‘synergy’ – from the Greek synergia – means ‘working together’. The concept of multiple elements working together towards a common goal has been extensively used in neuroscience to develop theoretical frameworks, experimental approaches, and analytical techniques to understand neural control of movement, and for applications for neuro- rehabilitation. In the past decade, roboticists have successfully applied the framework of synergies to create novel design and control concepts for artificial hands, i.e., robotic hands and prostheses. At the same time, robotic research on the sensorimotor integration underlying the control and sensing of artificial hands has inspired new research approaches in neuroscience, and has provided useful instruments for novel experiments.

The ambitious goal of integrating expertise and research approaches in robotics and neuroscience to study the properties and applications of the concept of synergies is generating a number of multidisciplinary cooperative projects, among which the recently finished 4-year European project “The Hand Embodied” (THE). This paper reviews the main insights provided by this framework. Specifically, we provide an overview of neuroscientific bases of hand synergies and introduce how robotics has leveraged the insights from neuroscience for innovative design in hardware and controllers for biomedical engineering applications, including myoelectric hand prostheses, devices for haptics research, and wearable sensing of human hand kinematics. The review also emphasizes how this multidisciplinary collaboration has generated new ways to conceptualize a synergy-based approach for robotics, and provides guidelines and principles for analyzing human behavior and synthesizing artificial robotic systems based on a theory of synergies.

Creating an artificial sense of touch through electrical stimuli


A study led by neuroscientists from UChicago shows that artificial touch is highly dependent on several features of electrical stimuli, such as the strength and frequency of signals, and describes the specific characteristics of these signals.

Source: Creating an artificial sense of touch through electrical stimuli