I-RIM Conference 2019 October 18 - 20, Rome, Italy ISBN: 9788894580501 Design of a parallel device for neurorehabilitation Jawad Yamine∗, Alessio Prini†, Tito Dinon†, Hermes Giberti‡ and Matteo Malosio† ∗Dipartimento di Meccanica, Politecnico di Milano, via La Masa 1, 20156 Milano, Italia Email: jawad.yamine@mail.polimi.it †Istituto di Sistemi e Tecnologie Industriali per il Manifatturiero Avanzato, Consiglio Nazionale delle Ricerche via Alfonso Corti, 12, 20133 Milano, Italia Email: alessio.prini@stiima.cnr.it, tito.dinon@stiima.cnr.it, matteo.malosio@cnr.it ‡Dipartimento di Ingegneria Industriale e dell’Informazione, Universit`a di Pavia, Via A. Ferrata 5, 27100 Pavia, Italia Email: hermes.giberti@unipv.it Abstract—This paper presents the mechanical architecture and the design of a 2DOF parallel device for upper-limb neurorehabil- itation. Geometric parameters have been obtained by optimizing kinematic performances. The prototype has been designed so that it can be bound on one side of a table with a clamp. The structure embeds two single-point load cells to measure the force exchanged with the patient, and to allow the execution of assist-as-needed therapies. Index Terms—Parallel kinematic architecture; kinematic op- timization; rehabilitation robotics; assist-as-needed control algo- rithms. I. INTRODUCTION Stroke is one of the main causes of long-term disability in the world and the most common in Western countries [1]. The number of patients having difﬁculties in performing activities of daily livings due to physical disabilities is constantly increasing while the number of therapists and caregivers is increasingly inadequate, creating an unmet market need. Robotic devices for neurorehabilitation have been widely investigated, developed and introduced to the market to offer an alternative to conventional therapy and meet a portion of the created need [2], [3]. Since the invention of the MIT-Manus [4], robot-assistance, force-feedback and force-based control are stat-of-the-art features of neurorehabilitation devices [5], enabling them to sense and react to patient interactions with the robot and adapt the level of physical assistance provided to the patient. Most of the proposed robots are technically advanced, but relatively expensive and designed for clinical settings, which makes it hard for patients to afford such treatment. On the other side, and focusing on upper-limb rehabilitation, a number of low-cost rehabilitation devices are currently available, but they are typically passive or passively gravity-balanced [6]. The lack of actuation and of an assist- as-needed support precludes them to be effectively used by patients with low-medium motion capabilities. Therefore, there is still a signiﬁcant need to develop home- based devices that provide similar or better functionality for a reduced cost. From there, rises the idea of our project that consists of designing and implementing a planar and relatively This work was partially funded by Fondazione Cariplo within the EMPA- TIA@Lecco project, Rif. 2016-1428 Decreto Regione Lombardia 6363 del 30/05/2017. affordable home-based upper-limb rehabilitation device that offers assist-as-needed functionalities to give the patient the best rehabilitation experience. Focusing on planar robotic devices for neurorehabilitation, two of them stand out in literature: the MIT-Manus [4] and the Braccio di Ferro [7]. A negative aspect of their structure is that both of them are characterized by a distribution of the inertia ellipses which are not symmetric, with respect to the sagittal plane of the patient. Zollo et al. faced this issues by developing a planar orthogonal device, characterized by an isotropic behavior throughout the whole workspace [8]. Nevertheless, in the opinion of the authors, such architecture is relatively cumbersome and complex to allow an effective commercial exploitation, especially in the domestic environment. For these reasons, a new device, namely PLANarm2, b