Fabrizio Vecchi

The SPRING Hand: Development of a Self-Adaptive Prosthesis for Restoring Natural Grasping

Commercially available prosthetic hands are simple grippers with one or two degrees of freedom; these pinch type devices have two rigid fingers in opposition to a rigid thumb. This paper focuses on an innovative approach for the design of a myoelectric prosthetic hand. The new prosthesis features underactuated mechanisms in order to achieve a natural grasping behavior and a good distribution of pinching forces. In this paper it is shown that underactuation allows reproducing most of the grasping behaviors of the human hand, without augmenting the mechanical and control complexity.

Mechatronic Design and Characterization of the Index Finger Module of a Hand Exoskeleton for Post-Stroke Rehabilitation

This paper presents HANDEXOS, a novel wearable multiphalanges device for post-stroke rehabilitation. It was designed in order to allow for a functional and safe interaction with the users hand by means of an anthropomorphic kinematics and the minimization of the human/exoskeleton rotational axes misalignment. This paper describes the mechatronic design of the exoskeletons index finger module, simulation, modeling, and development of the actuation unit and sensory system. Experimental results on the validation of the dynamic model and experimental characterization of the index finger module with healthy subjects are reported, showing promising results that encourage further clinical trials.

NEUROExos: A Powered Elbow Exoskeleton for Physical Rehabilitation

This paper presents the design and experimental testing of the robotic elbow exoskeleton NEUROBOTICS Elbow Exoskeleton (NEUROExos). The design of NEUROExos focused on three solutions that enable its use for poststroke physical rehabilitation. First, double-shelled links allow an ergonomic physical human-robot interface and, consequently, a comfortable interaction. Second, a four-degree-of-freedom passive mechanism, embedded in the link, allows the users elbow and robot axes to be constantly aligned during movement. The robot axis can passively rotate on the frontal and horizontal planes 30° and 40°, respectively, and translate on the horizontal plane 30 mm. Finally, a variable impedance antagonistic actuation system allows NEUROExos to be controlled with two alternative strategies: independent control of the joint position and stiffness, for robot-in-charge rehabilitation mode, and near-zero impedance torque control, for patient-in-charge rehabilitation mode. In robot-in-charge mode, the passive joint stiffness can be changed in the range of 24-56 N·m/rad. In patient-in-charge mode, NEUROExos output impedance ranges from 1 N·m/rad, for 0.3 Hz motion, to 10 N·m/rad, for 3.2 Hz motion.

A Cosmetic Prosthetic Hand with Tendon Driven Under-Actuated Mechanism and Compliant Joints: Ongoing Research and Preliminary Results

This paper presents recent results aimed at developing a functional prosthetic hand characterized by an EMG-control and by a simple and low cost fabrication technology. In order to overcome some limitations of current prosthetic hands mainly related to the poor functionality and controllability, the prosthetic hand has been designed following a biomechatronic approach based on biologically-inspired design solutions. The core of the project described in this paper is the fabrication of a compliant under-actuated prosthetic hand: the structure of the hand (both palm and fingers) is moulded as a soft polymeric single part with compliant joints and embedded tendon driven underactuated mechanism for providing adaptive grasp. In order to make user trials, the hand is equipped with simple but functional EMG-based control of the single motor incorporated in the hand, and is integrated with a prosthesis socket. The paper presents the biomechatronics design, the fabrication process, the integration of the prosthetic device and first experimental results.

Experimental analysis of an innovative prosthetic hand with proprioceptive sensors

This paper presents an underactuated artificial hand intended for functional replacement of the natural hand in upper limb amputees. The natural hand has three basic functionalities: grasping, manipulation and exploration. To accomplish the goal of restoring these capabilities by implanting an artificial hand, two fundamental steps are necessary: to develop an artificial hand equipped with artificial proprioceptive and exteroceptive sensors and to fabricate an appropriate interface able to exchange sensory-motor signals with the amputees body and the central nervous system. In order to address these objectives, we have studied an underactuated hand according to a biomimetic approach, and we have exploited robotic and microengineering technologies to design and fabricate its building blocks. The architecture of the hand comprises the following modules: an actuator system embedded in the underactuated mechanical structure (artificial musculoskeletal system), a proprioceptive sensory system (position and force sensors), an exteroceptive sensory system (3D force sensors distributed on the cosmetic glove), an embedded control unit, and a human/machine interface. The first prototype of the artificial hand has been designed and fabricated. The hand is underactuated, and is equipped with opposable thumb and a proprioceptive sensory system. This paper presents the fabrication and experimental characterization of the hand, focusing on the mechanical structure, the actuator system and the proprioceptive sensory system.

Robotics as a future and emerging technology: biomimetics, cybernetics, and neuro-robotics in European projects

The evolution of the paradigm of modern biomechatronics and robotics can be seen in two main directions, standing as two extremities of a range of future biomechatronics systems: increasing the performance and miniaturization of the hardware platform and increasing the intelligence of the integrated system. Regarding the first direction, the current challenge is to develop sophisticated machines with a higher level of miniaturization and performance, as they can be inspired by insects. Towards the other extremity, there is research on intelligent and autonomous robots, like humanoids. At intermediate levels, one can envisage the development of machines with a good degree of sophistication and performance and with a moderate degree of intelligence and that are more prone to human supervision and control or even to integration with natural bodies as bionic components. In this article, three projects funded by the European Commission in the 5th Framework Programme, in the Information Society Technology-Future and Emerging Technologies (IST-FET) program, are presented as implementing three levels of this evolution of the biomechatronic paradigm: from the biomimetic wormlike microrobot for endoscopic exploration to a cybernetic hand prosthesis to an anthropomorphic robotic platform implementing learning schemes for sensory-motor coordination in manipulation.

Sensing Pressure Distribution on a Lower-Limb Exoskeleton Physical Human-Machine Interface

A sensory apparatus to monitor pressure distribution on the physical human-robot interface of lower-limb exoskeletons is presented. We propose a distributed measure of the interaction pressure over the whole contact area between the user and the machine as an alternative measurement method of human-robot interaction. To obtain this measure, an array of newly-developed soft silicone pressure sensors is inserted between the limb and the mechanical interface that connects the robot to the user, in direct contact with the wearer’s skin. Compared to state-of-the-art measures, the advantage of this approach is that it allows for a distributed measure of the interaction pressure, which could be useful for the assessment of safety and comfort of human-robot interaction. This paper presents the new sensor and its characterization, and the development of an interaction measurement apparatus, which is applied to a lower-limb rehabilitation robot. The system is calibrated, and an example its use during a prototypical gait training task is presented.

HANDEXOS: Towards an exoskeleton device for the rehabilitation of the hand

This paper introduces a novel exoskeleton device (HANDEXOS) for the rehabilitation of the hand for post-stroke patients. The nature of the impaired hand can be summarized in a limited extension, abduction and adduction leaving the fingers in a flexed position, so the exoskeleton goal is to train a safe extension motion from the typical closed position of the impaired hand.

A Wearable Biomechatronic Interface for Controlling Robots with Voluntary Foot Movements

This paper presents an experimental investigation on a novel interface for high level control of mechatronic systems, by exploiting voluntary users foot movements. Based on a biomechanical analysis of the foot anatomy and joint kinematics, a sensory system is designed for detecting pressure variations on selected areas of the insole, obtained from four different foot movements that can be purposively controlled by the person. A prototype is developed that integrates four sensitive areas, battery, and electronics into a wearable insole; electronics are used for data acquisition and wireless transmission, in order to have a stand-alone device. The prototype foot interface is experimentally tested in the control of a prosthetic hand, as a model of a typical device that can be effectively operated by foot movements. Experimental trials were conducted with ten able-bodied subjects and the results confirmed the usability and effectiveness of the foot interface in terms of correct and prompt transmission of the users intention to the controlled device. Comparative experimental trials were performed with electromyography (EMG)-based control of the same prosthesis, which represents the most advanced interface currently available in clinical implants for amputees. The comparative results showed a significant decrease in required adaptation and learning from the users side

Development of an in-shoe pressure-sensitive device for gait analysis

In this work, we present the development of an in-shoe device to monitor plantar pressure distribution for gait analysis. The device consists in a matrix of 64 sensitive elements, integrated with in-shoe electronics and battery which provide an high-frequency data acquisition, wireless transmission and an average autonomy of 7 hours in continuous working mode. The device is presented along with its experimental characterization and a preliminary validation on a healthy subject.