Search Results (699)

Continuum robots offer inherent compliance and dexterity for operation in confined and unstructured environments; however, achieving hybrid multi-segment functionality typically requires application-specific redesign and tightly coupled architectures. To address this limitation, this study proposes a reconfigurable hybrid continuum robot architecture based around a multi-lumen central integration backbone that supports multiple actuation modalities and robot configurations. The proposed design combines external tendon-driven disk modules for proximal actuation with a pneumatically actuated distal tip, while internal lumens allow routing of pneumatic lines and the insertion of optional stiffening elements without structural interference. The reconfigurability of the architecture is demonstrated through two configurations: Concept-1, a two-segment hybrid system, and Concept-2, a miniaturized three-segment configuration achieved by reducing the disk diameter and extending tendon actuation to the backbone. Experimental evaluations are conducted to characterize segment-wise actuation, coupled deformation behavior, and workspace capabilities, hysteresis response, tip contact force, and phantom-based target reachability. Results show that the integration of tendon-driven and pneumatic actuation significantly expands and reorients the reachable workspace. Additional functional tests showed repeatable loading–unloading behaviour of the tendon-driven segment, a maximum pneumatic tip contact force of approximately 0.45 N, and successful access to five representative targets within a stomach-like phantom using Concept-2. A kinematic model based on a constant-curvature formulation is validated against experimental data, yielding root-mean-square errors (RMSE) of 5.44 mm and 6.12 mm for Concept-1 and Concept-2, respectively. These results demonstrate consistent model accuracy across different configurations and scales. Overall, the proposed architecture enables modular, scalable, and reconfigurable hybrid continuum robots, providing a flexible framework for applications ranging from large-scale manipulation to gastroscopy-inspired minimally invasive procedures. Full article

This study investigates the station planning problem of a mobile manipulator for robotic 3D concrete printing. The problem is formulated as a station planning problem considering two trajectory-level performance objectives: kinematic dexterity and structural stiffness. A directional dexterity metric based on the minimum normalized velocity directional manipulability along the task path is used to evaluate the worst-case motion capability of the manipulator during trajectory execution. A stiffness-related metric based on the maximum absolute Z-axis deformation of the end-effector is used to evaluate the worst-case deformation under operational loads. These two trajectory-level criteria are normalized and integrated through a weighted scalarization strategy, and a genetic algorithm is employed to search for station configurations under reachability constraints. Case studies on representative wall geometries show that the proposed method improves motion performance and reduces deformation compared with non-optimized station placements. The results indicate that the proposed framework provides an effective station planning strategy for mobile manipulators in trajectory-following robotic tasks. Full article

The dual-arm cooperative operation mode can effectively address the problems of insufficient load capacity and limited motion flexibility of traditional single-arm robots during the installation of construction boards. However, the selection of the end-effector grasping position of dual-arm robots will significantly affect their motion performance during handling operations. To address this issue, this study proposes an end-effector grasping strategy for sheet installation in the dual-arm cooperative operation mode of a dual-arm robot, which determines the optimal grasping position to ensure the robot’s good operational performance. We developed a dual-arm robot prototype for board installation and established a kinematic model of the robot’s manipulators. Based on the dexterity index’s service sphere, we obtained the dexterity envelope surfaces of the robot end-effector at different grasping distances and analyzed the relationship between grasping distance and dexterity. The mechanical model of the robot was established, and simulations were performed for each joint. The effects of different grasping points on the torque, stiffness, and stability at the robot’s key points were investigated, and the end-effector grasping range of the robot with optimal mechanical performance was analyzed. Finally, the proposed robot grasping strategy was verified on the robot prototype. The results demonstrate that the strategy is feasible and effective, helping to improve the robot’s operational performance. Full article

Robotic assistance in minimally invasive surgery has significantly improved precision and dexterity; however, many supportive tasks, such as blood aspiration, still rely on manual operation. This work presents the design and implementation of a supervised autonomous robotic aspirator for detecting and removing bleeding in an in vitro experimental model. The proposed system integrates a perception module based on a convolutional neural network for real-time blood segmentation, a task planner for high-level action execution, and a control strategy based on artificial potential fields for autonomous navigation. Additionally, a mixed-reality human–robot interaction interface is incorporated to enable system supervision and seamless transition to teleoperation when required. The system was experimentally validated with a set of in vitro experiments under three representative bleeding scenarios, evaluating four suction strategies based on the computation method for the target selection. Results demonstrate high blood removal rates (above 80% in all cases) and high suction efficiency. The comparative analysis reveals that the performance of the suction strategies is scenario-dependent and highlights a trade-off between suction efficiency and removed area. These findings support the feasibility of autonomous robotic aspiration and provide insights into the design of adaptive strategies for surgical assistance, contributing toward increased task autonomy and reduced need for continuous manual suction control during minimally invasive procedures. Full article

Deep reinforcement learning (DRL) has shown strong capability for multi-finger dexterous in-hand manipulation, where high-dimensional control and complex object interactions make policy learning challenging. However, many existing DRL approaches emphasize task completion and learning efficiency without explicitly accounting for manipulation risk, which can lead to overly aggressive behaviors and unstable object handling. This study proposes Risk-Prioritized Experience Replay (Risk-PER), a replay-sampling strategy that incorporates task-specific risk scores derived from prior transitions. The proposed method assigns each transition a risk score based on three binary indicators related to manipulation instability and then biases replay toward lower-risk experiences while still allowing the agent to learn from risk-related events. Risk-PER is integrated with Deep Deterministic Policy Gradient (DDPG) and evaluated in MuJoCo simulation on two Allegro Hand in-hand manipulation tasks involving a block and an egg. Across the evaluated settings, Risk-PER achieves higher success rates, lower manipulation risk, and more stable learning behavior than HER and reward–penalty-based risk-averse baselines. These results suggest that incorporating task-specific risk awareness into replay prioritization can improve both learning efficiency and manipulation stability in dexterous in-hand manipulation. Full article

Essential tremor (ET) is among the most prevalent movement disorders, causing significant impairment in manual dexterity and daily functioning. Although ET affects individuals across the lifespan, exercise intervention research has focused almost exclusively on older adults, leaving young adults, for whom early intervention may prevent long-term neuromuscular deterioration, critically underrepresented. Furthermore, the effects of strength–endurance oriented exercise combined with task-specific motor activities remain insufficiently explored in any ET population. This quasi-experimental pre-test–post-test study investigated the effects of a 6-week progressive strength–endurance and task-specific exercise program on tremor severity, manual dexterity, and upper extremity functional performance in young adult males with ET (n = 18; mean age: 22.6 ± 4.1 years). The 24-session intervention (four sessions/week) combined proximal upper extremity strength–endurance exercises with seven ADL-specific fine motor tasks. Tremor severity was assessed using the Fahn–Tolosa–Marin Tremor Rating Scale (FTMTRS), manual dexterity using the Nine-Hole Peg Test (NHPT), and upper extremity stability using the Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST). The Wilcoxon signed-rank test was used for within-group comparisons, with rank biserial correlation (r) and Cohen’s d reported as effect size indices. Significant pre-to-post improvements were observed across nearly all outcome measures, with medium-to-large effect sizes. Spiral drawing performance improved significantly in five of six conditions (r = 0.47–0.62), with the exception of the Spiral left–B task (p = 0.083). Postural tremor, NHPT (both hands), and CKCUEST also showed significant improvements (r = 0.47–0.73). A composite tremor score, integrating all tremor sub-scores, demonstrated a 14.1% overall reduction (p = 0.001, r = 0.83), providing strong evidence of program-wide effectiveness. Session adherence was 95.8%. To our knowledge, this is one of the first studies to show that a structured strength–endurance and task-specific exercise program was associated with reductions in tremor severity and improvements in upper extremity function, specifically in young adults with ET. These findings support the clinical utility of exercise as a non-pharmacological intervention in this underserved population and highlight the importance of early, targeted intervention during young adulthood. Full article

Recent progress in prosthetic manipulation highlights the need for perception-driven control strategies that can adapt to diverse objects and user intent. This work presents a modular vision-guided grasping pipeline that integrates VLM-based object identification, orientation-aligned geometric modeling, and per-finger grasp planning for dexterous prosthetic hands. A Vision–Language Model (VLM) identifies the target object and activates the grasping pipeline only when recognition is confident, supporting intent-aware operation. From the segmented point cloud, an object-aligned bounding box (OBB) is constructed to provide a compact, orientation-aware representation of the object’s global extents, enabling more accurate distance and collision queries than axis-aligned boxes. Using this representation, the system evaluates candidate fingertip trajectories and selects contact poses for each finger independently, followed by Damped Least Squares inverse kinematics for joint-level execution. Preliminary experiments on a limited set of representative objects using the Linker Hand O7 demonstrate that the proposed pipeline achieves consistent grasp execution and exhibits promising real-time performance within controlled scenarios. In simulation, the proposed pipeline achieved a maximum segmentation accuracy of 93.4%, while hardware experiments on the Linker Hand O7 achieved 93.2% segmentation accuracy, confirming stable grasp execution across representative objects. While the evaluation is not yet comprehensive, the results indicate that combining semantic object identification with lightweight geometric reasoning can support efficient and adaptable grasp generation suitable for future prosthetic applications. Full article

The Nine-Hole Peg Test (9-HPT) is widely used in clinical settings but typically relies on the assessor’s expertise to record execution time. Here, we propose a novel sensorized 9-HPT capable of automatically measuring total execution time and, importantly, extracting a set of newly defined temporal parameters that enable a more detailed and objective characterization of task performance. We first demonstrated concurrent validity between the sensorized 9-HPT and stopwatch-based measurements recorded by an assessor (ρ always > 0.98; p < 0.001) in healthy participants. Agreement between methods was further supported by the Bland–Altman analysis, showing negligible bias and narrow limits of agreement. A linear mixed-effects model confirmed no systematic differences between methods but showed significant differences between dominant and non-dominant hands. Test–retest reliability of total completion time, assessed across two sessions, was good for both the dominant (ICC = 0.81) and non-dominant (ICC = 0.74) hands. The newly introduced temporal parameters also showed significant reliability (ICC = 0.73–0.78), particularly for the dominant hand. Overall, these findings support the reliability of the sensorized 9-HPT for standard outcome measures and highlight its added value in providing novel temporal metrics that more precisely capture the different phases of task execution. Full article

In this paper, an engineering model (EM) of a multi-joint space gripper for on-orbit servicing (OOS) is proposed. OOS missions demand robotic systems capable of reliable physical interactions under dynamic uncertainties and harsh space environments. While prior space-qualified grippers have demonstrated dexterous manipulation through anthropomorphic, high-DoF configurations, this work adopts a design direction widely established in industrial applications: a three-finger, lower-DoF configuration that balances grasp versatility, structural simplicity, and system integration for OOS missions. The developed gripper features a tendon-driven mechanism with a structural design optimized for space-environment compatibility and mechanical compliance. The kinematic characteristics of the mechanism are analyzed, while workspace and manipulability analyses are conducted to evaluate its operational limits. To verify the functional feasibility of the proposed design, representative grasping experiments were performed using a fabricated EM. The mechanical reliability and grasping performance were evaluated through a series of empirical experiments. The results indicate that the proposed design achieves a practical balance among grasp versatility, structural simplicity, and system integration for OOS missions, with a shielding-oriented structural configuration adopted as a design baseline. Its functional feasibility is supported by kinematic analysis, repeatability verification, and grasping experiments. This study provides a basis for the design and evaluation of three-finger robotic grippers in future OOS missions. Full article

Background: Spinal cord injury (SCI) impairs sensorimotor function below the lesion and reshapes supralesional circuits, potentially influencing motor control above the injury. Although upper extremity strength and sensation are clinically normal in paraplegia, it is not known whether supralesional reorganization may produce subclinical alterations in the fine motor skills of the upper extremities. The aim of the study was to compare manual dexterity evaluated through the Purdue Pegboard Test between patients with SCI (PwSCI) and healthy subjects (HS). Methods: We recruited 18 PwSCI with complete paraplegia and 18 age- and sex-matched HS. Participants completed the four subtests of the Purdue Pegboard Test: dominant hand (1), non-dominant hand (2), bimanual (3), and assembly (4). For the first three subtests, a mixed 3 × 2 ANOVA (3 subtests × 2 groups) was performed, whereas for the fourth subtest, an independent samples t-test was performed. Spearman’s rho quantified correlations among subtests and with clinical findings. Results: PwSCI showed full upper extremity muscle strength and sensation. The mean scores of the four subtests were significantly lower in PwSCI than in HS. Unilateral and bimanual subtests correlated with each other in both groups; however, the bimanual subtest was not as well predicted by dominant hand alone, as PwSCI depended more on non-dominant ability. In PwSCI, the assembly subtest strongly depended on dominant, non-dominant, and bimanual scores, whereas this dependency was weaker in HS. The subtests were influenced by ageing in PwSCI. Conclusions: Despite upper extremity muscle strength and sensation being clinically normal, PwSCI showed impaired manual dexterity. This may reflect diminished ascending somatosensory input to supraspinal centres and plastic changes in supralesional motor pathways. These preliminary results open new rehabilitation perspectives for PwSCI. Full article

Background: Upper extremity deficits in unilateral cerebral palsy (UCP) severely restrict daily autonomy. Although movement-based priming is known to stimulate neuroplasticity, the distal transfer of lower extremity (LE) training to augment paretic upper limb (UL) function remains largely uninvestigated. This randomized controlled trial evaluated whether a 6-week LE cross-training (CT) priming regimen enhances UL functional restoration in pediatric UCP. Methods: Thirty-six children (6–8 years) were randomized to a conventional physical therapy cohort (n = 18) or an experimental CT cohort (n = 18). The CT group performed high-resistance contractions utilizing the non-paretic LE immediately preceding standard therapy. Blinded evaluations quantified Handgrip Strength (HGS) via dynamometry, grasping proficiency via the Peabody Developmental Motor Scales (PDMS-2), and gross dexterity via the Box and Block Test (BBT) pre and post intervention. Results: Analysis indicated a robust, near-significant between-group effect (Wilks’ Λ = 0.775, p = 0.057). While both cohorts achieved substantial internal improvements, the CT participants displayed superior developmental trajectories across all domains, notably in grasping age equivalence (34.28 ± 6.33 vs. 25.78 ± 3.26 months) and HGS (3.89 ± 0.79 vs. 3.03 ± 0.53 kg). Conclusions: LE cross-training priming may be a feasible adjunct, but it did not demonstrate statistically significant additional UL benefit versus standard rehabilitation in this sample. Therefore, these results should be interpreted as exploratory and hypothesis-generating. This potential cross-segmental transfer may theoretically operate via interhemispheric facilitation, warranting further investigation in larger, adequately powered trials. Full article

To address the challenge that existing soft grippers have difficulty achieving fine manipulation comparable to the human finger’s “circular twisting” motion, this paper proposes a four-chamber spatial bending soft actuator based on the principle of virtual work. The actuator incorporates an internal cross-shaped restricting layer that divides its cross-section into four independent pneumatic chambers. Through independent regulation of the pressure in each chamber, continuous and controllable bending in arbitrary spatial directions is achieved, replicating the bending and abduction/adduction degrees of freedom (DoFs) of a human finger and their composite motions on a single actuator. Based on the Yeoh hyperelastic constitutive model and the principle of virtual work, a static deformation model of the actuator is established. By introducing an engineering assumption of “deformation vector superposition” and correction coefficients fitted from experimental data, high-precision prediction from multi-chamber pressure input to spatial bending output is realized. Furthermore, a three-finger soft gripper is constructed based on this actuator, successfully demonstrating fingertip pinching and enveloping grasping. Through open-loop programmed control, the fine “circular twisting” manipulation is demonstrated (exemplified by light bulb installation). This study provides an effective structural design and modeling method for soft actuators to achieve decoupled multi-DoF motion control, showcasing their application potential in adaptability and dexterous manipulation. Full article

Thumb degree-of-freedom (DOF) allocation in anthropomorphic robot hands involves a trade-off between functional mobility and mechanical-control complexity. This study presents a controlled multi-metric framework for comparing recurring thumb DOF configurations under common palm geometry, non-thumb finger structure, reference frames, Denavit–Hartenberg kinematics, and sampling assumptions. Five literature-derived thumb configurations, namely 3-1-1, 2-2-1, 2-1-1, 2-0-1, and 1-1-1, were evaluated to determine which thumb DOFs should be preserved when kinematic complexity is reduced. The theoretical evaluation included Kapandji Opposition Test reachability, opposition alignment, workspace volume, workspace compactness, cylindrical grasp opportunity, and Jacobian-based dexterity. A targeted experimental validation of the 2-1-1 and 2-0-1 prototypes was then performed on a tendon-driven test bench. The results showed that qualitatively similar thumb configurations are quantitatively unequal: several designs achieved identical Kapandji scores but differed substantially in workspace, alignment, dexterity, and grasp feasibility. Overall, 3-1-1 achieved the strongest overall capability, while 2-2-1 emerged as the strongest reduced-complexity alternative and achieved the best mean dexterity. Retaining two active carpometacarpal DOFs preserved a large share of dexterous function, whereas metacarpophalangeal fixation maintained selected cylindrical grasps but narrowed the feasible task boundary. Full article

Background/Objectives: Recovery of upper limb function after stroke is highly heterogeneous, and accurate prediction of clinically meaningful functional transition remains a major challenge in rehabilitation medicine. We developed and temporally validated machine learning (ML)-based prognostic models for predicting transition from non-functional movement to functionally usable upper limb capacity in patients undergoing intensive inpatient rehabilitation during the early subacute phase of stroke. Methods: This retrospective cohort study included 960 patients with ischemic or hemorrhagic stroke admitted to a tertiary rehabilitation center between 2010 and 2025. Three functional recovery outcomes were defined: motor impairment recovery, defined as Fugl-Meyer Assessment for Upper Extremity score ≥ 32; gross manual dexterity recovery, defined as Box and Block Test score ≥ 2 blocks/min; and functional pinch strength recovery, defined as pinch strength ≥ 1.1 kgf. Multidimensional predictors spanning demographic, clinical, neurophysiological, neuroimaging, and rehabilitation-related domains were integrated. Four ML algorithms were evaluated using stratified 5-fold cross-validation and temporal validation in a chronologically independent cohort (2024–2025). Models were developed under two tracks: Track A, incorporating only baseline variables available at admission (primary prognostic model), and Track B, additionally incorporating cumulative rehabilitation-related variables (exploratory). Results: Random Forest demonstrated the best overall performance. During temporal validation, models achieved AUROC of 0.800 for motor impairment recovery, 0.958 for gross manual dexterity recovery, and 0.888 for functional strength recovery. Baseline motor severity and corticospinal tract integrity were the dominant biological determinants of recovery. Earlier rehabilitation initiation and greater upper-limb robot-assisted therapy exposure were also associated with improved outcomes; however, these findings should be interpreted as observational associations subject to treatment-selection bias rather than evidence of causal effects. Conclusions: Probabilistic ML prediction integrating neural reserve and rehabilitation-related exposure variables can support individualized precision rehabilitation planning and improve functional outcome stratification in early subacute stroke. Full article

Background and Objectives: Multiple sclerosis (MS) is characterized by progressive disability and a spectrum of motor and cognitive impairments. Exergames and virtual reality (VR) are proposed as motivating exercise tools, potentially useful for improving adherence and expanding access to rehabilitation. The objectives are to explore the feasibility and safety of a supervised rehabilitation program based on a high-intensity exercise program with immersive virtual reality (IVR) in people with MS and to describe its effects on physical, cognitive, and functional domains, as well as on the serum biomarker neurofilament light chain (sNfL). Materials and Methods: Pre–post exploratory study in five volunteers from a local MS Association [Vigo, Spain]. Intervention: 8 weeks, two sessions/week, 10 min/session of an IVR boxing-based exergame combined with usual rehabilitation, supervised by a physiotherapist. The variables studied were safety (Simulator Sickness Questionnaire [SSQ]), usability (System Usability Scale [SUS]), disability (Expanded Disability Status Scale [EDSS]), gait (25-Foot Walk Test [25FWT]), manual dexterity (9 Hole Peg Test [9HPT]), cognition (Symbol Digit Modalities Test [SDMT]), and axonal damage biomarker (sNfL). Results: The intervention could be feasible and safe (100% adherence, no adverse events (without SSQ symptoms), 95% usability [SUS]). There were positive changes in all variables studied (mean ± SD): EDSS −0.5 ± 0.9; 25FWT −4.9 ± 9.8 s; right 9HPT −3.3 ± 0.9 s; sNfL −4.4 ± 4.5 pg/mL, except for left 9HPT +0.5 ± 5.0 s and cognition (SDMT −2.4 ± 1.3 points). Conclusions: A brief, supervised exercise program combing an IVR exergame with standard rehabilitation was feasible and safe in people with MS. Although the results seem promising with the proposed design, the clinical and biological changes are merely exploratory, and it is not possible to infer their efficacy. Our findings open the door to future controlled studies including perceived high-intensity exercise programs and larger sample sizes to explore efficacy and estimate clinically relevant effect sizes. Full article