A hyperelastic torque-reversal mechanism for soft joints with compression-responsive transient bistability.

In this paper, a dynamic system consisting of a robot manipulator and a target is analyzed. The target is considered in a general way as a dynamic subsystem having finite mass and moments of inertia (e.g., a rigid body or a second robot). The situation investigated is when the robot establishes interaction with the target in such a way that it intercepts and captures a reference element of the target. The analysis of target capture is divided into three phases in terms of time: the precapture, “free” motion (finite motion); the transition from free to constrained motion in the vicinity of interception and capture (impulsive motion); and the postcapture, constrained motion (finite motion). The greatest attention is paid to the analysis of the phase of transition, the impulsive motion, and dynamics of the system. Based on the use of impulsive constraints and the Jourdainian formulation of analytical dynamics, a novel approach is proposed for the dynamic modeling of target capture by a robot manipulator. The proposed approach is suitable to handle both finite and impulsive motions in a common analytical framework. Based on the dynamic model developed and using a geometric representation of the system’s dynamics, a detailed analysis and a performance evaluation framework are presented for the phase of transition. Both rigid and structurally flexible models of robots are considered. For the performance evaluation analyses, two main concepts are proposed and corresponding performance measures are derived. These tools may be used in the analysis, design, and control of time-varying robotic systems. The dynamic system of a three-link robot arm capturing a rigid body is used to illustrate the material presented.

ConspectusPhotoelectrochemical (PEC) systems are among the most promising solar-to-electrochemical energy conversion and storage technologies and are uniquely positioned to address global energy demand and environmental sustainability. Mimicking the essential functions of natural photosynthesis, including light harvesting, catalytic water oxidation, CO2 reduction, and energy storage, requires materials that integrate efficient photon capture with rapid charge transport and robust catalytic activity. However, conventional photoelectrochemical materials are limited by the incomplete utilization of the solar spectrum and rapid charge recombination, leading to a narrowed redox potential window and compromised overall conversion efficiency. In this context, organic molecular PEC materials offer distinct advantages through their tunable, well-defined structures, enabling precise control over their electronic properties, redox behavior, and broad-spectrum light utilization. Integrating electron donor-acceptor (D-A) frameworks with redox-active or catalytic units into porous assemblies establishes spatially organized pathways for charge separation and catalytic transformation, although such a molecular-level design remains in its early stages. The central challenge lies in translating these structure-function insights into design principles that deliver multifunctional materials capable of controlled charge modulation, long-range electron transfer, and adaptive catalysis, thereby advancing the realization of complete artificial photosynthesis.In this Account, we begin with decoding PEC systems through the design principles of molecular materials, emphasizing how molecular-level modifications influence key performance metrics. The main concept of developing molecular materials through molecular engineering for artificial photosynthesis, centered on PEC energy conversion and storage, is presented in this Account. It focuses on the state-of-the-art construction of efficient D-A structures by tuning functional groups and incorporating single and dual metals, with charge dynamics regulated by thermodynamic and kinetic processes. Advances and challenges in molecular engineering are highlighted, emphasizing that designing efficient D-A architectures requires the appropriate selection of molecular functional groups, tailored structures, and optimized properties, which are crucial for regulating long-lived charge separation states and driving diverse redox reactions in PEC systems. We outline best practices for designing and assembling coupled D-A architectures, highlighting our research contributions and the broader progress in solar-to-electrochemical energy conversion and storage during the past decade. The discussion further explores coupled/decoupled strategies, which offer solutions to challenges associated with solar-driven CO2 splitting (for CO and O2 generation), N2 reduction (for NH3 synthesis), and organic molecular-level energy storage devices (solar batteries), and is extended to perspectives on sustainable development. Taken together, we anticipate that this Account will outline emerging strategies for integrating multifunctionality into PEC molecular assemblies, providing valuable design insights for adaptable materials that enhance solar-to-electrochemical energy conversion and storage efficiency.

Heterogeneous nanostructure array for electrochemical energy conversion and storage

In patients with total knee arthroplasty, the improvement of knee extensor muscle strength is an important factor in restoring stability, movement and function, and reducing pain. The purpose of this study was to investigate the effectiveness of cryotherapy to improve knee extensor strength and balance ability of total knee arthroplasty patients. In this study, 14 patients with total knee arthroplasty patients were recruited from a rehabilitation hospital. They were divided into two groups: a cryotherapy group (n=7) and a control group (n=7). They all received 30 minutes of continuous passive motion (CPM) and sit to stand training for 15 minutes and cryotherapy five times a week for two weeks. Knee extensor strength and balance ability were measured. Knee extensor strength was measured by Biodex system 3, balance ability was measured by Balancia software. To verify the difference in muscle strength and balance ability between groups, the pre-intervention value was set as a covariate and an analysis of covariance was performed. After the training period, the cryotherapy group showed a significant improvement in knee extensor muscle strength (p<0.05). There was no significant difference between groups in balance ability (p>0.05). This study examined the effect of cryotherapy on muscle strength and balance ability after rehabilitation exercise in patients with total knee arthroplasty. The cryotherapy after rehabilitation exercise was found to have an effect on muscle strength improvement. However, it did not affect the balance ability. Therefore, it is recommended to improve muscle strength by applying cryotherapy after rehabilitation exercise for total knee arthroplasty patients.

A pilot study on the design and validation of a hybrid exoskeleton robotic device for hand rehabilitation

Soft joint shape measurement is challenging because, in most cases, it relies solely on internal sensors. Existing shape estimation methods commonly take measurements at discrete points and utilize curve-fitting schemes, which are inefficient for complex joint shapes that require continuous measurements. Therefore joint shape measurement sensors rely on the fiber Bragg grating (FBG) due to its sensitivity, immunity to electromagnetic interference, and flexibility. Nevertheless, FBG demodulation is still an open research case. Hence, we propose a shape measurement device appropriate for FBG-based continuous measurements that employs a sensor with only three FBGs thrusting inside the soft joint to measure its 3D shape. Moreover, we develop a simple demodulating system exploiting the FBG's filter overlapping properties and design a calibrating process for FBG signals. Soft joint shape measurement experiments highlight our method's effectiveness, providing a relative error within 0.7%. Further tests involving continuum robot measurement reveal that the achieved precision is of the same level as a motion-capturing system.

Using a fluid-orbit coupling simulator, we numerically solve the three-dimensional Navier-Stokes equations with exchanging information of six-degree-of-freedom reactions for predicting impulsive flight motions of a laser propulsion vehicle driven by blast waves. By feedback of angular and translational velocities into the flowfield, pressure and viscous drags induced by the unsteady vehicle motion are introduced to provide precise motion analysis. In the impulsive-motion estimation of the laser-boosted vehicle, restoring forces and moments are underestimated if the vehicle motion effect is modeled using aerodynamic coefficients of steady flow. Also, a simple model using impulse data examined by experiments for predicting the impulsive motion is compared with our coupling approach which can reproduce instantaneous acceleration resulting from the interaction between the vehicle and the blast wave. Velocity overshoot is generated by evaluating sharp thrust through the coupling calculation, and the flight height becomes 6% larger than conventional prediction using the impulse data.

This paper presents a bio-mimetic flytrap robot based on the Venus flytrap, which has rapid snap-through motion. The robot employs a bi-stable unsymmetrically laminated carbon fiber reinforced prepreg (CFRP) structure, which has a bi-stable mechanism that is similar to the Venus flytrap's passive elastic mechanism. By embedding shape memory alloy springs, large deformation is induced and bi-stable structure can be triggered to snap through. The robot's working performance shows that the leaves close in about 100ms, and this time for closure is almost the same as that of the Venus flytrap. This concept of the flytrap robot can be applied to rapid grippers of various sizes.

Global tool-path smoothing for CNC machine tools with uninterrupted acceleration

Through a case study approach the motion of a dryline (on 16 May 1991) within a synoptically active environment in the southern plains, along which severe storms ultimately developed, is examined in detail. Observations from research aircraft, surface mesonetwork stations, mobile ballooning vehicles, radar, wind profilers, and operational surface and upper air networks are examined and combined. Additionally, output from the operational mesoscale Eta Model is examined to compare predictions of dryline motion with observations and to aid in interpretation of observations. The dryline on this day advanced rapidly eastward and included formation of a bulge; additionally, in at least two instances it exhibited redevelopment (loss of definition at one location and gain at another). Aircraft observations revealed that an eastward redevelopment occurred in the early afternoon and was characterized by a series of four “steps” along the western edge of the boundary layer moisture. The westernmost and easternmost steps coincide with the locations of the dryline before and after redevelopment, respectively. The retreat of the dryline in the central and southern portion of the analysis domain in the late afternoon included both continuous motion and redevelopment toward the west-northwest. This dual-mode retreat of the dryline was accompanied by gradual backing of the winds and moistening in low levels. The Eta Model forecast initialized at 1200 UTC produced dryline features that were qualitatively similar to observed fields. The eastward motion of a broad area of enhanced moisture gradient agreed well with observations following an initial spinup period. A north–south moisture convergence axis preceded the rapid eastward motion of the dryline by several hours. Lack of subsidence in the air behind the modeled dryline leads to the conclusion that processes other than downward transfer of horizontal momentum by larger-scale motions (that would support eastward advection) produced the rapid dryline motion and observed eastward dryline bulge. Results of diagnosing physical processes affecting model dryline motion point toward boundary layer vertical mixing coupled with advection of dry air aloft as vital components in rapid advance of the dryline eastward in this synoptically active case.

The design of structures that combine the principles of minimum energy and bistable mechanisms is presented. A minimum energy configuration is achieved by the interaction of one or more elastic elements and two strips of stretched elastomer, which also operate as dielectric actuators. The system has two equilibrium states, and the actuators are used to trigger the switch from one state to the other. An analytical model, based on the approach of energy minimization, was implemented to assist the design of the geometrical parameters. A prototype shows bistability and is able to switch equilibrium state varying its bending angle from −40° to 40°.

The synergistic integration of acoustic metasurfaces with the adaptive reconfigurability of origami art has demonstrated significant promise in thedynamic modulation of sound waves. This paper proposes an innovative approach to acoustic metasurfaces that incorporates bistable origami-inspired folding structure and digital coding to enable dynamic reconfiguration of beam scanning. The unit cell of the metasurface is optimized to realize two equilibrium states with 180-degree phase difference that can be coded as binary 0 and 1. In particular, by programming each element of the metasurface with different coding sequences, two symmetric reflected acoustic beams can be manipulated at different angles. The proposed design signifies a noteworthy advancement in the field of acoustic metasurfaces, offering a flexible and versatile solution applicable to acoustic imaging, communication, and sensing applications.

Correlations among flexibility, stiffness, strength and muscle ultrasound parameters in older males afflicted with hamstrings tightness

Effective physiotherapy interventions are required for haemophilic arthropathy (HA) of the elbow due to its biomechanical differences and contribution to upper limb functionality. To investigate the effects of manual therapy & exercises on bleeding frequency, pain, range of motion (ROM), strength, joint health, functionality and quality of life (QoL) in HA of the elbow. Seventeen participants with HA of the elbow were randomized as Manual Therapy & Exercises Group (MTEG=9) and Home Exercises Group (HEG=8). Soft tissue mobilization, joint traction (grade I-II) and Mulligan's mobilization with movement as manual therapy, and stretching/strengthening exercises were applied to MTEG, while HEG had only same exercises as home programme. The interventions lasted 3days/weekly for 5weeks. Bleeding frequency was evaluated with patients' records; pain with Numeric Pain Scale; ROM with goniometer; strength with digital dynamometer; joint health with HJHS; functionality with Quick-Disability of Arm, Shoulder and Hand questionnaire; and QoL with Oxford Elbow Score. Bleeding frequency and activity pain were decreased, while elbow ROMs and flexor strength were increased in MTEG (P˂0.05). Also significantly improvements were seen in joint health, functionality and QoL in MTEG. HEG showed improvements in activity pain, QoL and some ROMs. MTEG had better results in ROMs, joint health and functionality (P˂0.05). Manual therapy & exercises may be used without causing bleeding and pain to increase the functionality, joint health and QoL, and is superior to home exercise for joint health and functionality. Home exercises may be ameliorated in pain, QoL and some ROMs.

Soft, thin, skin-integrated electronics, i.e. epidermal electronics, has become a hotspot in biomedical engineering and drawn great attention for their applications in health monitoring, disease diagnosis and therapies. However, soft powering system is still a challenge for epidermal electronics, since the thickness and weight of the existing flexible energy harvesting and storage devices are very hard to meet the requirements of epidermal electronics. Here we present a stretchable and flexible self-powering epidermal electronic device based on rubbery piezoelectric composites formed by a ternary blend of PDMS, lead zirconate titanate (PZT) and graphene. The mixed PZT rubber is soft, ultra-thin and light weight and intrinsically stretchable. By combining soft PDMS substrate and advanced mechanics designed interdigital electrodes/interconnects, a stretchable and skin-integrated device for tactile sensing is realized. The soft device can not only accurately measure a board range of force from 2.84 kPa to 11.72 kPa but also exhibit great flexibility that can maintain stable performance under various mechanical deformations, such as bending, stretching and twisting. On-skin demonstration tests reveal that this self-powering device can clearly distinguish the differences among mechanical stimulations such as touching, poking, tapping and hitting. Furthermore, the self-powering nature of these devices allows energy to be harvested from daily body actives, for instance, hard touching by hand can lighten up to 15 light-emitting diodes.