SynGrasp – A MATLAB Toolbox for Grasp Analysis of Human and Robotic Hands

SynGrasp is a new MATLAB Toolbox developed by SIRSLab for the analysis of grasping, suitable both for robotic and human hands. Download it from SynGrasp Website!

Grasp analysis for underacuated hands with synergies

This  post summarizes the research at SIRSLab on grasping with underactuated compliant robotic hands in the recent years. These studies have been realized  SIRSLab also in collaboration with other Universities and research centres, e.g. University of Pisa and DLR.

The complexity of robotic hands is needed to adapt themselves to the many kinds of tasks, but the large number of motors needed to fully actuate the DoFs comes at the cost of size, complexity and weight of devices. A possible approach to solve this problem consists of reducing the number of actuators thus resulting more efficient, simpler and reliable than their fully actuated alternatives. Reducing control inputs seems to inspire also biological systems and in particular motor control of human hands, which share with robotic hands the large number of DoFs.

Reducing the number of control inputs, from fully actuated joints to few synergies, might reduce the dimension of the force and motion controllability subspaces thus compromising the dexterity of the grasp. In [PrMaBi11] and later in [GaBiPrMa11] we introduced the compliance in the quasi-static model at the contact points, at the joints and at the synergy actuation synergies. In particular, the introduction of compliance at the synergy level was referred to as soft synergies.

The solution of the quasi-static grasp problem when only a few actuators are present in the hand is possible if compliance is introduced in the model. In

We investigated the main structural properties of grasping with underactuated hands and in particular to what extent a hand with many DoFs can exploit postural synergies to control force and motion of the grasped object.

An underactuated robotic hand with compliance at the contact, joint and synergy level.


The analysis of grasp in terms of possible motions of the manipulated object and reachable internal forces has been investigated for robotic hands with underactuation in [PrMaBi11] using explicit manipulation of input and output variables and in [PrMaGaBi11] an using implicit analysis based on the study of the kernel of a system of equations. Both approaches explicit and implicit lead to the same results but the explicit one is more easy to read in terms of control actions.

In [GaBiPrMa11] the authors investigated the role of synergies in the optimal choice of contact forces in grasping.

In [MaPr13] we described some preliminary evaluations on grasping properties with underactuated hands and in particular we evaluated grasp stiffness in hands with passive joints.


In [MaPr11, PrMaAgWi12] the authors studied an interesting problem: when the robotic hand has not enough degrees of freedom and present compliance, it is possible that if you change the internal force the grasped object moves, due to the different deformation of the equivalent contact springs. These papers implicitly consider the underactuated hands as those hands with fewer DoFs with respect to those needed to control internal forces without moving the object. The results of this study have been applied to a real robotic hand, the experimental tests are described in [PrMaAgWi13].

Main publications on this topic:

[PrMaBi11] D. Prattichizzo, M. Malvezzi, A. Bicchi. On motion and force controllability of grasping hands with postural synergies. In Robotics: Science and Systems VI, pp. 49-56, The MIT Press, Zaragoza, Spain, June 2011. [pdf]

[PrMaGaBi11] D. Prattichizzo, M. Malvezzi, M. Gabiccini, A. Bicchi. On the Manipulability Ellipsoids of Underactuated Robotic Hands with Compliance. Robotics and Autonomous Systems, Elsevier, 2012. [pdf]

[GaBiPrMa11] M. Gabiccini, A. Bicchi, D. Prattichizzo, M. Malvezzi. On the role of hand synergies in the optimal choice of grasping forces. Autonomous Robots, Springer, 31:235-252, 2011. [pdf]

[MaPr11] M. Malvezzi, D. Prattichizzo. Internal force control with no object motion in compliant robotic grasps. In Intelligent Robots and Systems (IROS), 2011 IEEE/RSJ International Conference on, Pages 1008-1014, September 2011. [pdf]

[PrMaAgWi12] D. Prattichizzo, M. Malvezzi, M. Aggravi, T. Wimboeck. Object motion-decoupled internal force control for a compliant multifingered hand. In Proc. IEEE Int. Conf. on Robotics and Automation, 2012. [pdf]

[MaPr13] M. Malvezzi, D. Prattichizzo, Evaluation of Grasp Stiffness in Underactuated Compliant Hands,  Accepted at IEEE Int. Conf. on Robotics and Automation, 2013. [pdf-draft]

[PrMaAgWi13] D. Prattichizzo, M. Malvezzi, M. Aggravi, T. Wimböck Compliant robotic hands with a low number of actuators: controlling grasping forces without affecting the object motion, submitted to the International Journal of Robotics Research, 2013.

Robotic hand, object displacements and contact forces obtained in the numerical experiments presented in [PrMaAgWi12], first row: controlling only the contact forces, without compensating the object motion; second row: with the proposed object motion-decoupled control. The left figures show the initial

hand and object configuration, the right ones the final.

Current Research in Robotics at the SIRSLab in Siena (Dipartimento di Ingegneria dell'Informazione)

In these slides I outlined the current research activity of the SIRSLab in Robotics at the University of Siena.

Domenico Prattichizzo

Wearable Haptics / Cutaneous devices / Mechano-tactile devices / Skin devices / Cutaneous-Kinesthetic dissociation / Sensory subtraction / Needle insertion: the research so far in our SIRSLab



This short post summarizes the research on wearable haptics and sensory subtraction in the recent years. The wearable cutaneous devices we have developed are presented in [1]. We have used them in several applications but the most relevant work employing them, which aims at comparing the performance of kinesthetic and cutaneous feedback, is [2]. In [2,3] we analyzed the performance of cutaneous and kinesthetic feedback in a simple teleoperation task (needle insertion in 1 DoF) pointing out how cutaneous feedback can improve the overall safety of the system. After that, we have developed other types of cutaneous devices. For instance the one presented in [4] can be attached to the end-effector of commercial kinesthetic devices (such as the Omegas) in order to be able to easily switch between cutaneous + kinesthetic and cutaneous only.

To get wearability in haptics it is very important to deal with the skin. Devices we are developing are able to apply cutaneous forces without  kinesthetic force feedback. This is of course an issue but it is mandatory if we want to have wearable device. It is a requirement for the design of the devices. Which are the errors we get in using cutaneous only stimulation instead of kinesthetic feedback? To which extent we can avoid kinesthetic feedback ? An answer to this questions has been provided in [6] in cooperation with K. Minamizawa, who developed the gravity grabber which inspired our research on wearable haptics.


Publications/Videos/pdf also available on our website (

[1] F. Chinello, M. Malvezzi, C. Pacchierotti, D. Prattichizzo. A three DoFs wearable tactile display for exploration and manipulation of virtual objects. In Proc. IEEE Haptics Symposium (HAPTICS), Volume, Pages 71-76, Vancouver, Canada, 2012. [pdf]

[2] D. Prattichizzo, C. Pacchierotti, G. Rosati. Cutaneous force feedback as a sensory subtraction technique in haptics. IEEE Transactions on Haptics, PrePrint available on IEEEXplore, 2012. [pdf]

[3] C. Pacchierotti, F. Chinello, D. Prattichizzo. Cutaneous device for teleoperated needle insertion. In Proc. 4th IEEE RAS EMBS Int. Conf. on Biomedical Robotics and Biomechatronics (BioRob), Pages 32-37, Rome, Italy, 2012. [pdf]

[4] C. Pacchierotti, F. Chinello, M. Malvezzi, L. Meli, D. Prattichizzo. Two finger grasping simulation with cutaneous and kinesthetic force feedback. In Haptics: Perception, Devices, Mobility, and Communication. Eurohaptics 2012, Lecture Notes in Computer Science, Pages 373-382, Tampere, Finland, 2012. [video] [pdf]

[5]  K. Minamizawa, D. Prattichizzo, S. Tachi. Simplified Design of Haptic Display by Extending One-point Kinesthetic Feedback to Multipoint Tactile Feedback. In IEEE Haptic Symposium, Pages 257-260, Waltham, Massachusetts, USA, 2010. [video] [pdf]



The Next Step in Robotic Neurosurgery | Techland |

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In the European Project ROBOCAST, leaded by Politecnico di Milano, the research unit at Dipartimento di Ingegneria dell’Informazione at the University of Siena designed and developed the haptic loop. As reported in the article:

“Needles and catheters inserted through the skull can then be moved by a probe operated by a surgeon, who can feel the resistance of the brain thanks to an advanced haptic device which gives tactile feedback to the operator of the machine. In the future, the probe will be used to perform surgical procedures not possible today, such as allowing surgeons to take a curved path from an entry point in the skull to a targeted lesion.”

Read more:

The article on

A movie on our youtube channel

Scientific paper

D. De Lorenzo, E. De Momi, R. Manganelli, I. Dyagilev, A. Formaglio, D. Prattichizzo, M. Shoham, G. Ferrigno. Force feedback in a piezoelectric linear actuator for neurosurgery. The International Journal of Medical Robotics and Computer Assisted Surgery, 2011

Domenico Prattichizzo

Presentation of our experiment project HANDS.DVI

Our experiment project Hands.dvi has been recently presented at IROS and at AUTOMATICA.IT. For more details check the section News on hands.dvi website.

Il progetto RemoTouch selezionato per l’Expo di Shangai 2010


Il progetto RemoTouch è stato selezionato come uno dei progetti meritevoli per la presentazione all’EXPO SHANGAI 2010 Expo nell’ambito dell’iniziativa “Italia degli Innovatori” promossa dal Ministro per la Pubblica Amministrazione e l’Innovazione, Renato Brunetta, e il Commissario Generale del Governo per l’Expo 2010, Beniamino Quinteri.

Il progetto REMOTOUCH è stato selezionato insieme ad altri 265 progetti per la realizzazione di una mostra temporanea all’EXPO SHANGAI 2010 con eventi collaterali dedicati alle eccellenze tecnologiche con l’obiettivo di mettere in evidenza l’ingegno e la tradizionale inventiva italiana.

Il Ministro Brunetta ed il Commissario Generale del Governo, Beniamino Quinteri hanno tenuto una conferenza stampa sull’iniziativa Italia degli Innovatori nell’ambito della quale il progetto REMOTOUCH è stato presentato insieme ad altre cinque idee innovative.

Il comunicato stampa del ministero è leggibile al seguente indirizzo

Il progetto del nostro Dipartimento è REMOTOUCH ed è reperibile al seguente indirizzo

In breve cosa è RemoTouch:

RemoTouch è un progetto svolto dal nostro Dipartimento in cooperazione con la Tokyo University per lo sviluppo di tecnologie e applicativi per “toccare a distanza”. L’esempio paradigmatico è quello riportato in un video del sito ( dove una mamma con un guanto sensorizzato tocca un bambino e trasmette a distanza le informazioni tattili al compagno che, attraverso un guanto attuato, percepisce in tempo reale l’esperienza tattile acquisita attraverso la mano della mamma

Il sistema può essere anche utilizzato per registrare esperienze tattili per poi riviverle a distanza di tempo.

Il tatto è l’unico dei cinque sensi che ha recettori sparsi su tutto il corpo e spesso è utilizzato in modo quasi inconsapevole. Il tatto è essenziale nella vita di tutti i giorni: senza il feedback tattile sarebbe molto difficile eseguire compiti semplici come ad esempio afferrare una penna e non potremmo accorgerci di eventuali situazioni di pericolo derivanti dal contatto con oggetti.

Negli ultimi anni abbiamo assistito ad un grande sviluppo e diffusione dei dispositivi elettronici volti alla “remotizzazione” dell’udito (microfoni e altoparlanti integrati nei telefoni) e della vista (telecamere e schermi dei portatili). La loro capillare diffusione ha inoltre consentito un notevole abbattimento dei costi ed una riduzione delle dimensioni a beneficio della portabilità.

RemoTouch è uno dei primi esempi di esperienza tattile remota ottenuta con dispositivi semplici, portatili e a basso costo. Si ritiene che le tecnologie per la trasmissione e per la comunicazione tattile saranno sempre più diffuse nei prossimi anni. La comunicazione tattile, può essere importante in molti contesti. Oltre a quello prima rappresentato dove c’è un grande coinvolgimento emotivo dovuto al contatto con il proprio figlio, si pensi alle comunicazioni di tipo commerciale dove ad esempio la trama e la consistenza del cuscino di un divano o di un abito viene trasmessa a distanza a qualcuno che non è potuto recarsi al particolare punto vendita. RemoTouch può essere di grande interesse in molti ambiti. In quello medico, si immagini ad esempio di poter registrare l’esperienza tattile di un paziente che esegue un esercizio di riabilitazione per poi riproporlo al medico curante o al fisioterapista per la verifica delle prestazioni. Nei social network, si immagini di arricchire la comunicazione audio video o chat con la trasmissione di sensazioni tattili per aumentare la sensazione di presenza in ambienti remoti.

Questo progetto ha visto un coinvolgimento degli studenti, in paritocolare, Claudio Pacchierotti, Lenorado Meli e Francesco Chinello, e di molti colleghi del nostro Dipartimento e senza i quali non si sarebbero potuti ottenere i risultati di cui stiamo parlando.

Per maggiori informazioni si rimanda

*** alla Conferenza Stampa del Ministero per la pubblica amministrazione e l’innovazione

*** Articolo su Affari e Finanza / Repubblica del 22 Marzo 2010

*** al sito del progetto RemoTouch