Hybrid wearable robotics, combining soft and rigid elements, offer a promising solution for upper limb assistance by balancing comfort and functionality. This study evaluates a hybrid soft-rigid elbow exosuit designed for elbow movement support in dynamic and endurance tasks, focusing on biomechanical impact, user perception, and ergonomics. A theoretical model guided the design, optimizing device dynamics and assistive force delivery. A generic interaction controller, combined with fixed system parameters, provided effective assistance across participants without the need for subject-specific tuning, simplifying deployment in practical settings. During dynamic tasks, the exosuit significantly reduced biceps muscle activity compared to the unassisted condition, with an average reduction of 28.40%. In endurance tasks, it reduced infraspinatus activity by an average of 44.55% and mitigated increased muscle activation during load-carrying. Subjective assessments indicated lower perceived physical demand, while the System Usability Scale confirmed high usability and acceptance. These findings highlight the exosuit's ability to reduce physical effort and improve muscle coordination while maintaining comfort. The robust mechatronic design enabled effective assistance through a generic controller, emphasizing the importance of hardware reliability.

Work-related musculoskeletal disorders (WMDs) affect a high percentage of operators performing repeated weight lifting and load carrying in industrial scenarios. Since upper limb muscles are affected in the process, the assistance provided by upper body exoskeletons is increasingly needed to prevent WMDs and their consequent cost to the health system. This paper presents the evaluation of Flexos, a portable, bilateral, shoulder exoskeleton prototype designed to assist logistic and industrial operators in performing occupational tasks. An in-lab assessment was conducted on twelve healthy subjects - 9 males, 3 females - to evaluate Flexos capability in assisting the user during the execution of isometric, dynamic, and carrying-load tasks. Different metrics were extracted from time-series signals to assess the effort related to five targeted muscles surrounding the shoulder complex. Despite the limited experimental size and the prototypal level of the device, Flexos managed to cover almost all the shoulders range of motion - 89.2% flexion/extension, and 88.4% internal/external rotation - and to globally decrease muscular activity in occupational activities, particularly when isometric contractions are required for a prolonged time, with average reductions of -27.2% for the static task, -18.6% for the dynamic task and -23.4% for the carrying-load task.

The intention-detection strategy used to drive an exosuit is fundamental to evaluate the effectiveness and acceptability of the device. Yet, current literature on wearable soft robotics lacks evidence on the comparative performance of different control approaches for online intention-detection. In the present work, we compare two different and complementary controllers on a wearable robotic suit, previously formulated and tested by our group; a model-based myoelectric control (myoprocessor), which estimates the joint torque from the activation of target muscles, and a force control that estimates human torques using an inverse dynamics model (dynamic arm). We test them on a cohort of healthy participants performing tasks replicating functional activities of daily living involving a wide range of dynamic movements. Our results suggest that both controllers are robust and effective in detecting human–motor interaction, and show comparable performance for augmenting muscular activity. In particular, the biceps brachii activity was reduced by up to 74% under the assistance of thedynamic armand up to 47% under themyoprocessor, compared to a no-suit condition. However, themyoprocessoroutperformed thedynamic armin promptness and assistance during movements that involve high dynamics. The exosuit work normalized with respect to the overall work was$68.84 \pm 3.81\%$when it was ran by themyoprocessor, compared to$45.29 \pm 7.71\%$during thedynamic armcondition. The reliability and accuracy of motor intention detection strategies in wearable device is paramount for both the efficacy and acceptability of this technology. In this article, we offer a detailed analysis of the two most widely used control approaches, trying to highlight their intrinsic structural differences and to discuss their different and complementary performance.

In this paper, we present a novel prototype of a flat and compact series elastic actuator (SEA) intended for use in assistive and portable upper limb exoskeletons. The elastic joint in series to the brushless motor is based on reliable and robust linear tension springs to achieve a high torque to weight ratio while keeping the design simple and cheap. A method to design the spring stiffness, based on the joint requirements, is proposed, and the torque controller for the device is presented. Characterization experiments have been carried out to verify the concept model and to tune and validate the torque estimator based on the elastic joint. The SEA exhibits suitable performance for the intended application: 39.7 Hz bandwidth in closed-loop torque control; about 0.2 Nm RMS torque in transparency operations; stability and acceptable torque tracking performance in compliant control mode.

Search and rescue robotics is becoming a relevant topic in the last years and the growing number of robotic platforms and dedicated projects is the evidence of the interest in this area. In this context, the possibility to drive a remote robot with an exoskeleton is a promising strategy to enhance dexterity, reduce operator effort and save time. However, the use of haptic feedback (bilateral teleoperation) may lead to instability in the presence of communication delay and more complex is the case of bimanual teleoperation where the two arms can exchange energy. In this work, we present a bimanual teleoperation system based on an exoskeletal master, where multi-degrees of freedom (multi-DoFs) and kinematically different devices are involved. In the implemented architecture the two slaves are managed in parallel and independently passivated using the Time Domain Passivity Approach (TDPA) extended for multi-DoFs devices. To investigate the stability of the architecture we designed two tasks highly related to real disaster scenarios: the first one was useful to verify the system behavior in case of small movements and constrained configurations, whereas the second experiment was designed to involve larger contact forces and movements. Moreover, we compared the effect of both delay and low control loop frequency on the stability of the system when TDPA was applied. From the results, it was evident that the overall system exhibited a stable behavior with the use of the TDPA, even passivating the two slaves independently, under simulated time delay and in presence of a low control loop frequency.

This paper presents the development and the experimental validation of a controller for the simulation of the behavior of automotive automatic gearshifts. For this purpose a gearshift simulator was developed based on 2 DOF haptic interface to evaluate users qualitative judgment of automatic gearshifts response. In fact, many car manufacturers use vehicle and primary controls simulators to evaluate the characteristics of a new model before building physical mock-ups or even prototypes. A dedicated control law was designed in order to reproduce different experimentally measured force profiles during forward and backward run of the gearshift handle. The force feedback control law was based on an impedance model with different stiffness values along the path of the gearshift. A state machine selects the characteristics of the force feedback profile according to lever position and velocity. An additional state machine implements the hysteresis behavior of the force profiles by a transition function. The transition algorithm and constraints related to stability are discussed in this paper. The rendered force/position profiles were obtained from experimental data using a real gearshift. Several gearshift response profiles were tested and simulated and experimental results were compared and highlighted good fidelity in force reproduction.