1,721,008 research outputs found
Biomimetic Tactile Sensing for Hannes Anthropomorphic Prosthetic Hand
No full textA prosthetic device replicating the human hand capabilities is very challenging to achieve, not only for the intrinsic nature of the very complex movements, anthropomorphism, and aesthetics but also for the sophisticated capabilities that its net of receptors offers from the somatosensory perspective. Therefore, providing seamless human hand capabilities in a single device is still an open topic. Hannes Hand prosthesis exemplifies advancements in prosthetic technology, and, for this research activity, a preliminary integration of P(VDF-TrFE) piezoelectric sensors enhances novel tactile sensing capabilities. This study focuses on the sensorization of the Hannes Hand, aiming to bridge the gap between human hand functionalities and prosthetic performance. We present a preliminary implementation of sensor arrays embedded within the prosthetic glove, ensuring high sensitivity and responsiveness. Our approach aims at emphasizing sensor fusion toward the development of comprehensive feedback and intuitive control. Through a preliminary comparison analysis with human mechanoreceptors, we highlight the effectiveness of our piezoelectric sensors in replicating rapid adaptive behaviours, crucial for dynamic interaction with the environment
Improving SEA Joint Torque Sensing for Enhanced Torque Estimation in Human-Machine Interaction
No full textEstimating human-robot interaction (HRI) in rehabilitative robotics poses challenges from both mechatronics and control standpoints. In this study, the authors introduce a method to tackle non-linear effects impacting Series Elastic Actuator (SEA) mechatronic systems. Achieving an accurate characterization of the SEA system enables improved torque estimation based on spring deformation. By improving torque sensing capabilities, the objective is to enhance HRI assessment for patient evaluation and enable compliant closed-loop control. The adopted method involves experimental testing, subjecting the SEA to mechanical stress under various load conditions. Experiments were conducted to explore SEA characteristics across different load configurations: joint at the bench with no-load, low-medium-high load, and joint assembled on an exoskeleton prototype. Analysis of the data revealed variability in SEA torque estimation errors, with higher loads associated with greater errors. To mitigate these errors and enhance torque estimation, the non-linearities have been characterized using two Fourier series (5th and 8th order) in both no-load and load conditions. Theoretical approaches and experimental results of this SEA characterization methodology will be presented to demonstrate the feasibility of this approach
Finite element modeling of an energy storing and return prosthetic foot and implications of stiffness on rollover shape
Full text linkEnergy storing and return (ESAR) prosthetic feet showed continuous improvements during the last 30 years. Despite this, standard guidelines are still missing to achieve an optimal foot design in terms of performances. One of the most important design parameters in ESAR feet is the Rollover Shape (RoS). This represents the foot Center of Pressure (CoP) path in a shank-based coordinate system during stance. RoS objectively describes the foot behavior according to its stiffness, which depends on foot geometry and material. This work presents the development of a finite element modeling methodology able to predict the stiffness characteristic of an ESAR foot and its RoS. The validation of the model is performed on a well-known commercially available prosthetic foot both in bench tests and realistic walking scenario. The obtained results confirm an error of +6.1% on stiffness estimation and +10.2% on RoS evaluation, which underlines that the proposed method is a powerful tool able to replicate the mechanical behavior of a prosthetic foot
Design Improvements to the Float Upper-Limb Exoskeleton Better Mimics the Glenohumeral Complex Kinematics
No full textThe shoulder glenohumeral complex stands out as one of the most complex structures within the human body. Designing a system that can effectively interface with it poses a significant challenge for researchers. In this study, we propose a methodology based on evaluating various metrics to assess the performance of new kinematic solutions for mimicking the glenohumeral complex. The proposed method is demonstrated on an existing design (Float) of an upper-limb exoskeleton. The results show a successful expansion of the reachable workspace and enhancement of the shoulder internal-external rotation. The improvements ensure the necessary range-of-motion for the patient’s natural use of the exoskeleton. Specifically, the existing Eulerian wrist architecture is replaced with a 3-degree-of-freedom RPY wrist to better resemble the glenohumeral shoulder joint complex. This study also explores the trade-offs between these enhancements and the desired system manipulability
Development of a high backdrivable partially powered Swing assistive actuator knee design: a multiobjective optimization framework
Full text linkThis manuscript presents a multiobjective optimization framework for high backdrivable partially powered swing assistive actuator knee design. The research exploits a Serial Elastic Actuator (SEA), in parallel with a motor valves controlled hydraulic cylinder, with the purpose of expanding the prosthesis capabilities into the power quadrants of the power plane, without sacrificing the benefits relative to existing microprocessorcontrolled-knee prostheses (MPKs), able to allow a strictlypassive ballistic swing-phase. The mechatronic design parameters are optimized by exploiting the multi-objective evolutionary genetic algorithm and validated by means of a knee prosthesis multibody model. The backdrive torque found with the described model corresponds to a relatively low value of 2.56 Nm at the knee joint, allowing the pursued high backdrivability of the system
A Preliminary Approach to Assessing Scapular Synergies with the FloatEvo Exoskeleton
No full textRobotic rehabilitation is increasingly adopted to enhance intensity and quality of rehabilitative sessions after traumatic events. Exoskeletons, in particular, show promise in delivering precise, intensive, and physiologically relevant physical therapy. Beyond providing movement guidance, these technologies can also be used to monitor and measure patient activity, with a particular focus on human kinematics, such as range of motion and motion synergies. In the context of upper limb rehabilitation, this study presents a preliminary investigation into the FloatEvo capability to monitor scapular rhythm and synergy exclusively through its integrated sensors
Long-Term Upper-Limb Prosthesis Myocontrol via High-Density sEMG and Incremental Learning
Full text linkNoninvasive human-machine interfaces such as surface electromyography (sEMG) have long been employed for controlling robotic prostheses. However, classical controllers are limited to few degrees of freedom (DoF). More recently, machine learning methods have been proposed to learn personalized controllers from user data. While promising, they often suffer from distribution shift during long-term usage, requiring costly model re-training. Moreover, most prosthetic sEMG sensors have low spatial density, which limits accuracy and the number of controllable motions. In this work, we address both challenges by introducing a novel myoelectric prosthetic system integrating a high density-sEMG (HD-sEMG) setup and incremental learning methods to accurately control 7 motions of the Hannes prosthesis. First, we present a newly designed, compact HD-sEMG interface equipped with 64 dry electrodes positioned over the forearm. Then, we introduce an efficient incremental learning system enabling model adaptation on a stream of data. We thoroughly analyze multiple learning algorithms across 7 subjects, including one with limb absence, and 6 sessions held in different days covering an extended period of several months. The size and time span of the collected data represent a relevant contribution for studying long-term myocontrol performance. Therefore, we release the DELTA dataset together with our experimental code
Knee prosthesis powered by a fully integrated and highly back-drivable electro-hydrostatic actuator
No full textIn this paper, we propose the design and experimental validation of an electro-hydrostatic actuator, as an alternative to traditional actuation technologies, for a powered knee prosthesis. The aim is to demonstrate that the adopted system-level design yields a highly integrated, lightweight, back-drivable device able to satisfy the biomechanical torque and speed requirements of the knee. Moreover, the back-drivable nature of the actuators allows for active and regenerative operations in the four quadrants of the torque-speed plane. In the context of knee biomechanics, this could lead to a potential advantage with respect to other powered prosthetic solutions, in terms of power consumption and device autonomy. Different control strategies, such as position, admittance and regenerative braking controllers, are implemented and tested on a dedicated rig to validate the design choices and demonstrate the prosthesis functionality and performance
Comparative analysis of inverse kinematics methodologies to improve the controllability of rehabilitative robotic devices
No full textThe solution of the inverse kinematics problem in multi-degrees of freedom robots has been tackled, through the last three decades, by several different approaches including analytical, geometrical, differential and numerical methods. All these techniques present their own advantages and drawbacks. However, a guideline on which approach is better to follow, depending on the kind of task to perform and the type of robotic device used, is still missing. In this work, a quantitative comparative analysis of three different inverse kinematics methodologies for the control of rehabilitative robotic devices is proposed, with aim of devising best practices and guidelines for the selection of the most suitable approach. The analyzed methodologies are implemented and numerically tested on two actual devices, specifically an upper-limb exoskeleton and an upper-limb prosthetic arm
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