Raffaele Molino Lova

CYBERLEGs: A User-Oriented Robotic Transfemoral Prosthesis with Whole-Body Awareness Control

Restoring the mobility of transfemoral dysvascular amputees is essential to their rehabilitation process. Impeding the restoration of mobility, exhaustion is often the cause of noneffective deambulation of elderly lowerlimb amputees using a prosthesis as they use more energy for locomotion than younger amputees do. This article presents finite-state control of a novel powered prosthesis prototype for transfemoral amputees based on whole-body awareness. Intention detection was implemented through a noninvasive, distributed wireless wearable sensory system. The cybernetic lower-limb cognitive orthoprosthesis (CYBERLEGs) system was evaluated in a study involving three amputees. The subjects were able to walk with the prosthesis without training, showing accurate performance of the intention detection. The functionality of the CYBERLEGs approach was confirmed by gait pattern analysis and intention detection statistics.

Walking Assistance Using Artificial Primitives: A Novel Bioinspired Framework Using Motor Primitives for Locomotion Assistance Through a Wearable Cooperative Exoskeleton

Bioinspiration in robotics deals with applying biological principles to the design of better performing devices. In this article, we propose a novel bioinspired framework using motor primitives for locomotion assistance through a wearable cooperative exoskeleton. In particular, the use of motor primitives for assisting different locomotion modes (i.e., ground-level walking at several cadences and ascending and descending stairs) is explored by means of two different strategies. In the first strategy, identified motor primitives are combined through weights to directly produce the desired assistive torque profiles. In the second strategy, identified motor primitives are combined to serve as neural stimulations to a virtual model of the musculoskeletal system, which, in turn, produces the desired assistive torque profiles.

Experimental Validation of Motor Primitive-Based Control for Leg Exoskeletons during Continuous Multi-Locomotion Tasks

An emerging approach to design locomotion assistive devices deals with reproducing desirable biological principles of human locomotion. In this paper, we present a bio-inspired controller for locomotion assistive devices based on the concept of motor primitives. The weighted combination of artificial primitives results in a set of virtual muscle stimulations. These stimulations then activate a virtual musculoskeletal model producing reference assistive torque profiles for different locomotion tasks (i.e., walking, ascending stairs, and descending stairs). The paper reports the validation of the controller through a set of experiments conducted with healthy participants. The proposed controller was tested for the first time with a unilateral leg exoskeleton assisting hip, knee, and ankle joints by delivering a fraction of the computed reference torques. Importantly, subjects performed a track involving ground-level walking, ascending stairs, and descending stairs and several transitions between these tasks. These experiments highlighted the capability of the controller to provide relevant assistive torques and to effectively handle transitions between the tasks. Subjects displayed a natural interaction with the device. Moreover, they significantly decreased the time needed to complete the track when the assistance was provided, as compared to wearing the device with no assistance.

Whole Body Awareness for Controlling a Robotic Transfemoral Prosthesis

Restoring locomotion functionality of transfemoral amputees is essential for early rehabilitation treatment and for preserving mobility and independence in daily life. Research in wearable robotics fostered the development of innovative active mechatronic lower-limb prostheses designed with the goal to reduce the cognitive and physical effort of lower-limb amputees in rehabilitation and daily life activities. To ensure benefits to the users, active mechatronic prostheses are expected to be aware of the user intention and properly interact in a closed human-in-the-loop paradigm. In the state of the art various cognitive interfaces have been proposed to online decode the users intention. Electromyography in combination with mechanical sensing such as inertial or pressure sensors is a widely adopted solution for driving active mechatronic prostheses. In this framework, researchers also explored targeted muscles re-innervation for an objective-oriented surgical amputation promoting wider usability of active prostheses. However, information kept by the neural component of the cognitive interface deteriorates in a prolonged use scenario due to electrodes-related issues, thereby undermining the correct functionality of the active prosthesis. The objective of this work is to present a novel controller for an active transfemoral prosthesis based on whole body awareness relying on a wireless distributed non-invasive sensory apparatus acting as cognitive interface. A finite-state machine controller based on signals monitored from the wearable interface performs subject-independent intention detection of functional tasks such as ground level walking, stair ascent, and sit-to-stand maneuvres and their main sub-phases. Experimental activities carried out with four transfemoral amputees (among them one dysvascular) demonstrated high reliability of the controller capable of providing 100% accuracy rate in treadmill walking even for weak subjects and low walking speeds. The minimum success rate was of 94.8% in performing sit-to-stand tasks. All the participants showed high confidence in using the transfemoral active prosthesis even without training period thanks to intuitiveness of the whole body awareness controller.

Motor primitive-based control for lower-limb exoskeletons

Assistive technology forecasts better autonomy for people with lifelong disabilities and for the elderly facing motor decline. As the population of developed countries is becoming greyer, there is thus a high probability of observing a significant increase in the demand for assistive locomotion devices. Designing the controller for such devices is not trivial, and requires both to set up a compliant framework and to manage the cross adaptation between the device and its user (the so-called interface). Taking inspiration from neuromechanical principles governing human locomotion is an approach which is currently investigated by several groups to address these challenges. In this contribution, we develop a bio-inspired controller based on motor primitives for lower-limb assistance. Motor primitives are combined in order to generate muscle stimulations that serve as neural inputs to a virtual musculoskeletal model, which in turn produces reference sagittal joint torques. This controller is also adaptable to different configurations of lower-limb exoskeletons and sensory inputs. This paper further reports the validation of the controller through two different experiments. Results showed the capability of the controller to provide coherent joint torque profiles for different configurations and locomotion tasks. These profiles could be used as assistive torques by scaling them as a function of the level of support being required, and transmitting them through an assistive device like an exoskeleton.

A Portable Active Pelvis Orthosis for Ambulatory Movement Assistance

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.

Gastrocnemius Myoelectric Control of a Robotic Hip Exoskeleton Can Reduce the User's Lower-Limb Muscle Activities at Push Off

We present a novel assistive control strategy for a robotic hip exoskeleton for assisting hip flexion/extension, based on a proportional Electromyography (EMG) strategy. The novelty of the proposed controller relies on the use of the Gastrocnemius Medialis (GM) EMG signal instead of a hip flexor muscle, to control the hip flexion torque. This strategy has two main advantages: first, avoiding the placement of the EMG electrodes at the human–robot interface can reduce discomfort issues for the user and motion artifacts of the recorded signals; second, using a powerful signal for control, such as the GM, could improve the reliability of the control system. The control strategy has been tested on eight healthy subjects, walking with the robotic hip exoskeleton on the treadmill. We evaluated the controller performance and the effect of the assistance on muscle activities. The tuning of the assistance timing in the controller was subject dependent and varied across subjects. Two muscles could benefit more from the assistive strategy, namely the Rectus Femoris (directly assisted) and the Tibialis Anterior (indirectly assisted). A significant correlation was found between the timing of the delivered assistance (i.e., synchronism with the biological hip torque), and reduction of the hip flexors muscular activity during walking; instead, no significant correlations were found for peak torque and peak power. Results suggest that the timing of the assistance is the most significant parameter influencing the effectiveness of the control strategy. The findings of this work could be important for future studies aimed at developing assistive strategies for walking assistance exoskeletons.