Papers by Matteo Fantozzi
Institution of Engineering and Technology eBooks, Mar 24, 2018
In the last years compliant actuators have become extremely popular in the field of wearable robo... more In the last years compliant actuators have become extremely popular in the field of wearable robotics, due to their ability to realize safe human-robot interfaces. One of the most well-known example of a compliant actuator is the series elastic actuator (SEA), consisting of an elastic element (e.g. a spring) in series with a stiff actuator; such actuation architecture is considered to be the simplest design solution to realize compliant, compact, and light-weight actuators for wearable robots; in addition, from the control perspective, SEA architecture allows for simple force or torque control in addition to position control. In this chapter, three wearable robots for upperand lower-limb rehabilitation and assistance, developed at The BioRobotics Institute of Scuola Superiore Sant'Anna, are described. The three devices have similar SEA-based actuation units, integrating commercial electromagnetic motors and custom torsional springs, with constant stiffness and linear torque-deformation characteristics. Closed-loop torque control performance show that the systems can be highly transparent when controlled under zero-torque modality, i.e. the interaction with the human is minimal and the actuators do not hinder the user's movement, and bandwidths and output torques are compatible with the human movements to be assisted.
Mechatronics, Oct 1, 2023
IEEE robotics and automation letters, 2022
This study presents a novel torque-controlled hand exoskeleton, named HandeXos-gamma, which uses ... more This study presents a novel torque-controlled hand exoskeleton, named HandeXos-gamma, which uses a series-elastic actuator (SEA)-based architecture to allow a compliant actuation of the hand joints, and an intention decoding algorithm that combines surface electromyography (sEMG) signals with kinematic information from the exoskeleton's encoders. The algorithm was developed offline using data acquired from healthy subjects who performed two grasping movements (lateral and power grasp) under different operating conditions while wearing the exoskeleton. Performance was evaluated for three variants of the algorithm: one using sEMG signals only, another using kinematic data only, and the last combining sEMG and kinematic data. Results indicated that the combination of the two modalities conferred greater algorithm performance than sEMG alone, thus supporting a new paradigm for adaptive robotic hand rehabilitation.
Biosystems & biorobotics, Oct 13, 2016
Wearable lower-limb powered othoses represent valid tools for assisting people affected by gait d... more Wearable lower-limb powered othoses represent valid tools for assisting people affected by gait disorders given their capability to actively sharing the workload of energetically expensive tasks of activities of daily living, contrarily to passive lower-limb orthoses or braces. In this abstract we present the design of an active knee orthotic joint, endowed with a novel series elastic actuator, and the experimental characterization of its torque controller. Experimental results demonstrated that the performance of the active knee joint are suitable for assisting locomotion-related activities of mildly impaired people.
Lower-limb loss is a dramatic event affecting quality of life and often reducing independence. Mo... more Lower-limb loss is a dramatic event affecting quality of life and often reducing independence. Moreover, lower-limb losses are foreseen to double by 2050. An active Knee-Ankle Foot Orthosis (KAFO) could represent an assistive tool for lower-limb amputees to reduce the extra-torque typically generated by the muscles of the sound limb due to compensatory strategies adopted to deal with a passive prosthesis during gait. Within the CYBERLEGs project, a novel active KAFO was designed to assist the knee and the ankle joints during ground level walking. In this paper the mechatronic design of the device is presented for the first time. Moreover, the paper presents the control strategy developed to provide knee and ankle assistance and the experimental results with two volunteers with lower-limb amputation. The KAFO was shown to: (i) fulfill all the design functional requirements to comply with range of motion, torque, speed and power; and (ii) provide assistive torque in the most demanding phases of the gait cycle. Tests with end-users showed that the assistive action resulted in physiological profiles of the knee and ankle angles and torques, showing a first proof of feasibility for the presented system. Both subjects reported comfortable interaction with the exoskeleton, but results on the metabolic consumption were not conclusive. This feasibility study will be extended in the future with an optimized controller to further explore the effectiveness of the system. I. MOTIVATIONS Worldwide, the main causes of lower-limb amputation are vascular disorders, such as diabetes and peripheral arterial diseases and the incidence of those is foreseen to grow in the next years, leading to twice as many amputations in 2050 compared to 2005. By then, more than 2 million people are expected to undergo a lower-limb amputation only in the USA [1]. Lower-limb loss is a dramatic event affecting health and quality of life, in many cases reducing independence and causing psychological distress. Indeed, typically dysvascular amputees adopt a slower gait speed of that of non-amputees (about 40%) and expend 2.5 times the energy that non-amputees expend. Consequently, physical
IEEE transactions on medical robotics and bionics, Feb 1, 2019
As a consequence of limb loss, trans-femoral amputees exert 60% additional knee extension torque ... more As a consequence of limb loss, trans-femoral amputees exert 60% additional knee extension torque and 50% more plantar flexion torque in the healthy limb compared to nonamputees. In this paper, we developed an active knee-ankle-foot orthosis (KAFO) designed to assist the healthy leg of transfemoral amputees in activities of daily living, such as walking, ascending/descending stairs, and transitioning from sit-to-stand with adequate range of motion, speed, and peak torque. Our KAFO was designed to exceed the performance of similar assistive devices reported in literature in terms of: 1) portability; 2) power; 3) compliance; and 4) versatility. It is based on onedegree-of-freedom active series-elastic actuators in both the knee and ankle, with an additional passive degree of freedom at the ankle level to allow natural inversion/eversion. The knee module consists of a worm-gear surrounded by two pre-compressed springs. The ankle actuator relies on a mechanically adjustable compliance system combined with a 4-bar linkage transmission. The actuators were designed to optimize the torque output at the joints while fulfilling low-power requirements. This novel KAFO is controlled with a three-layer structure. The optimized low level, based on a closed-loop torque controller, has adequate performances for the targeted application. The device is also shown to fulfill the three pre-defined functional requirements for all locomotion modes.
WORLD SCIENTIFIC eBooks, Aug 28, 2018
Wearable Technologies
Passive ankle-foot prostheses are light-weighted and reliable, but they cannot generate net posit... more Passive ankle-foot prostheses are light-weighted and reliable, but they cannot generate net positive power, which is essential in restoring the natural gait pattern of amputees. Recent robotic prostheses addressed the problem by actively controlling the storage and release of energy generated during the stance phase through the mechanical deformation of elastic elements housed in the device. This study proposes an innovative low-power active prosthetic module that fits on off-the-shelf passive ankle-foot energy-storage-and-release (ESAR) prostheses. The module is placed parallel to the ESAR foot, actively augmenting the energy stored in the foot and controlling the energy return for an enhanced push-off. The parallel elastic actuation takes advantage of the amputee’s natural loading action on the foot’s elastic structure, retaining its deformation. The actuation unit is designed to additionally deform the foot and command the return of the total stored energy. The control strategy o...
Grazie all’aumento delle potenze elettriche disponibili a bordo delle nuove generazioni di veicol... more Grazie all’aumento delle potenze elettriche disponibili a bordo delle nuove generazioni di veicoli spaziali, la propulsione elettrica offre vantaggi sempre maggiori rispetto a quella chimica, soprattutto per gli enormi vantaggi logistici. Dagli anni '90 ad oggi i propulsori ad effetto Hall si sono sempre più affermati come soluzione in campo spaziale per le manovre di station-keeping e riposizionamento orbitale. Negli ultimi anni, a causa dei costi sempre crescenti dello Xenon, il propellente convenzionalmente usato nei propulsori a effetto Hall, si è iniziato a sperimentare l’uso di propellenti alternativi. Il presente lavoro di tesi descrive parte di una campagna sperimentale, svolta presso i laboratori di Alta S.p.A., mirata a determinare il punto di funzionamento e le prestazioni di un propulsore a effetto Hall del tipo SPT-100 da 1,5 kW di potenza nominale, utilizzando come propellente sia azoto puro, sia una miscela di azoto e ossigeno. Nella parte centrale del lavoro si d...
IEEE Transactions on Medical Robotics and Bionics, 2019
As a consequence of limb loss, trans-femoral amputees exert 60% additional knee extension torque ... more As a consequence of limb loss, trans-femoral amputees exert 60% additional knee extension torque and 50% more plantar flexion torque in the healthy limb compared to nonamputees. In this paper, we developed an active knee-ankle-foot orthosis (KAFO) designed to assist the healthy leg of transfemoral amputees in activities of daily living, such as walking, ascending/descending stairs, and transitioning from sit-to-stand with adequate range of motion, speed, and peak torque. Our KAFO was designed to exceed the performance of similar assistive devices reported in literature in terms of: 1) portability; 2) power; 3) compliance; and 4) versatility. It is based on onedegree-of-freedom active series-elastic actuators in both the knee and ankle, with an additional passive degree of freedom at the ankle level to allow natural inversion/eversion. The knee module consists of a worm-gear surrounded by two pre-compressed springs. The ankle actuator relies on a mechanically adjustable compliance system combined with a 4-bar linkage transmission. The actuators were designed to optimize the torque output at the joints while fulfilling low-power requirements. This novel KAFO is controlled with a three-layer structure. The optimized low level, based on a closed-loop torque controller, has adequate performances for the targeted application. The device is also shown to fulfill the three pre-defined functional requirements for all locomotion modes.
Biosystems & Biorobotics, 2016
Aging of population and increased incidence of gait impairments are dominant trends undermining s... more Aging of population and increased incidence of gait impairments are dominant trends undermining social welfare and healthcare system. Lower-limb wearable robots proved to be a viable solution for recovering mobility of people affected by gait disorders. This work presents the design of the mechatronic architecture of a fully self-contained active pelvis orthosis (APO) for assisting hip flexion/extension movements during daily living activities. The APO could act compliantly with the human biomechanics thanks to series-elastic actuation and to a novel kinematics chain endowed with passive degrees of freedom. The portability and autonomy of the control system have opened the horizon to explore different assistive tasks in out-of-lab scenarios.
Robotics and Autonomous Systems, 2015
h i g h l i g h t s • Development of a novel lightweight wearable powered bilateral pelvis orthos... more h i g h l i g h t s • Development of a novel lightweight wearable powered bilateral pelvis orthosis. • Design of a novel compact, lightweight series-elastic actuator (SEA). • SEA closed-loop torque control bandwidth equal to 15 Hz. • SEA output impedance ranges from 1 to 35 N m /rad in human gait frequency spectrum. • The overall system usability was proved by tests with a healthy subject.
The Encyclopedia of Medical Robotics
Lower-limb loss is a dramatic event affecting quality of life and often reducing independence. An... more Lower-limb loss is a dramatic event affecting quality of life and often reducing independence. An active Knee-Ankle-Foot Orthosis (KAFO) could represent an assistive tool for lower-limb amputees to reduce the additional metabolic effort resulting from compensatory strategies due to walking with a passive prosthesis. Within the CYBERLEGs project, a novel active KAFO was designed to assist the knee and the ankle joints during ground level walking. In this paper the mechatronic design of the device is presented for the first time. Moreover, the paper presents the control strategy developed to provide knee and ankle assistance and the experimental results with two volunteers with lower-limb amputation. The KAFO was shown to: (i) fulfill all the design functional requirements to comply with range of motion, torque, speed and power; and (ii) provide assistive torque in the most demanding phases of the gait cycle. Tests with end-users showed that the assistive action resulted in physiologi...
— Gait impairment is a common consequence with people getting old, bringing a great inconvenience... more — Gait impairment is a common consequence with people getting old, bringing a great inconvenience for their daily life. In this paper, a lightweight active pelvis orthosis is used to provide assistance to improve the mobility of the elderly. An adaptive oscillator based control strategy is proposed to predict the next status of a hip joint angle. Then the desired assistive torque is estimated by multiplying the predicted and current angle difference by a virtual stiffness. This control strategy is evaluated with an elder subject walking on the treadmill wearing the orthosis. Experiment results showed usability of the device for elderly gait assistance. Under transparent mode utilization, the orthosis does not hinder intentional movement of the wearer while, under assistive mode utilization, it is capable to provide user with a suitable assistive torque.
IEEE Robotics and Automation Letters
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Papers by Matteo Fantozzi