Compliant Device Research Articles

A hybrid ankle-foot orthosis with soft pneumatic actuation

This paper presents the design, development, and analysis of a powered ankle-foot orthosis for dorsiflexion assistance which aims to improve gait restoration by addressing issues related to orthosis misalignment, limited degrees of freedom, restricted range of motion, and muscular disuse. The proposed orthosis utilizes a novel hybrid design with a combination of both traditional and soft robotics for compliant and unrestrictive ankle dorsiflexion assistance for sufferers of footdrop. This article describes the complete design of the orthosis including analytical modeling and experimental testing of the soft pneumatic actuator and the development of gait phase detection and ankle angular feedback systems using wearable sensors for accurate and responsive control. Preliminary analysis was completed which validates the orthosis as a lightweight, unrestrictive, and compliant device that is capable of dorsiflexing the ankle of a person up to 100 kg, and at walking speeds appropriate for safe and effective community ambulation of up to 1.04 m/s. The novel design of the device demonstrates the potential for improved rehabilitative outcomes for patients with footdrop, due to the ability to adjust the assistive force of the device, throughout the progression of rehabilitation, which encourages muscular participation of the user and therefore reduces issues caused by muscular disuse.

A green compliant hand-held selective electrode device for monitoring active pharmaceuticals and the kinetics of their degradation

An in-line smartphone connected to a screen-printed selective electrode hand-held device was used to determine the concentration of distigmine bromide (DB) in its pure and dosage forms as well as its degradation kinetics by continuously measuring the change in the produced emf over time. The main objective, supported by the data presented, is to produce a highly reliable smartphone integrated selective sensor as a portable analyzer with potential high cloud connectivity combining a wide linear dynamic range, the fastest response time with the lowest limits of detection and quantitation while best integrating green analytical chemistry principles. The choice of ionophore used in this approach was guided by computation and the data obtained was compared with traditional analytical techniques. DB, for which there are no previously reported stability-indicating methods and for which four novel such methods are proposed here, was selected as a model drug for this work. At-line UV-spectrophotometry DB assay was obtained by measuring the difference between the spectra of the degradation product and the same concentration of intact drug. The degradation kinetics were studied by this method through tracking the decrease of DB absorbance and/or the increase of a generated degradation product signal over time. Off-line separation based HPLC and TLC stability-indicating methods for DB were also presented. All methods employed in this work were validated for accuracy, precision, specificity, repeatability, linearity, range, detection and quantification limits according to the ICH guidelines and were applied to the analysis of laboratory prepared mixtures as well as commercial products. While all methods proposed were shown to be highly reliable, the smartphone integrated selective sensor is highlighted as a portable analyzer with potential high cloud connectivity and was shown to combine a wide linear dynamic range, the fastest response time with the lowest limits of detection and quantitation while best integrating green analytical chemistry principles.

Flippable and Hermetic E-Band RWG to GCPW Transition With Substrate Embedded Backshort

In this article, a novel millimeter wave (mm-wave), fully hermetic and flippable transitioning structure between grounded coplanar waveguides (GCPWs) and rectangular waveguides (RWGs) is introduced. This transition, realized through standard printed circuit board (PCB) technology, can be employed to feed a waveguide (WG) compliant device on any face of a board given its flexibility in trace routing and component placement. The proposed structure utilizes a mix of transmission line and substrate integrated waveguide (SIW) interconnected with an in-substrate embedded back-short. The transition, in all its configurations, targets a fractional bandwidth (FBW) wider than 20% to cover the commercial <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$</tex-math> </inline-formula> -band spectrum. Moreover, at center frequency the predicted insertion loss (IL) for both normal and flipped transitions is 0.4 and 0.46 dB, respectively. Parametric and yield analyses, together with postmanufacturing inspections have been performed to assess the robustness of the design and to identify the critical manufacturing inaccuracies. The experimental validations confirm the wideband operation with an IL bounded below 2.3 dB for the worst case of a back-to-back configuration.

Research on Robotic Compliance Control for Ultrasonic Strengthening of Aviation Blade Surface

In order to satisfy the requirement of the automatic ultrasonic strengthening of an aviation blade surface, this paper puts forward a robotic compliance control strategy of contact force for ultrasonic surface strengthening. By building the force/position control method for robotic ultrasonic surface strengthening., the compliant output of the contact force is achieved by using the robot’s end-effector (compliant force control device). Based on the control model of the end-effector obtained from experimental determination, a fuzzy neural network PID control is used to optimize the compliance control system, which improves the adjustment accuracy and tracking performance of the system. An experimental platform is built to verify the effectiveness and feasibility of the compliance control strategy for the robotic ultrasonic strengthening of an aviation blade surface. The results demonstrate that the proposed method maintains the compliant contact between the ultrasonic strengthening tool and the blade surface under multi-impact and vibration conditions.

Design of a compliant device for peg-hole separation in robotic disassembly

Disassembly is the first step in the remanufacturing of a product. This paper presents the design of a robot end-of-arm tool for removing a peg from a hole, a common operation in the disassembly of mechanical products. The device is a compliant structure that enables the peg to be pulled out of a closely fitting hole without jamming or wedging. The device is reminiscent of the Remote Centre Compliance (RCC) mechanism used by assembly robots to insert cylindrical pegs into cylindrical holes with small clearances. However, whereas the RCC mechanism has primarily to withstand compressive forces, the proposed compliant device must resist tensile forces because of the nature of disassembly operations. The paper details a finite-element modelling study of peg removal with and without using the compliant structure. The results obtained show that the structure markedly reduces the stresses at the points of contact between the peg and the hole and, consequently, the risk of damage to the components being disassembled.

Design and hybrid impedance control of a new compliant wrist rehabilitation device

Over a decade, wrist rehabilitation robots have been proved to be efficient in the rehabilitation of patients with stroke or wrist injuries. Wrist rehabilitation devices compensate for deficiencies in manual rehabilitation training and reduce the workload of physiotherapists with their repetitive and gradual training necessary to rehabilitate patients with wrist impairments properly. Two design approaches have been reported in literature for wrist rehabilitation robotic devices. In one design approach, the strategy of placing the actuators, either linear or rotary, on the forearm to minimise the weight and inertia has been proposed. This necessitates a use of sophisticated transmission systems. In the other design approach, rotary motors have been proposed to be placed directly on the wrist joints, which results in a high weight and inertia. In this paper, a new 2-DOF compliant wrist rehabilitation device that can achieve the flexion-extension and radial-ulnar rehabilitation movements compliantly is proposed. In the proposed design, two series elastic actuators (SEAs), each consists of a servomotor and a custom-designed series elastic unit, are proposed to be placed directly on the wrist joints. In order to minimise the inertia and the required torques, the device is counterweight balanced by optimising the centre of mass of the device in the SolidWorks model. Based on the device dynamics modelled by ADAMS software, hybrid position and force tracking impedance control with the incorporation of a disturbance observer controller for the rotary SEA is developed for position and force tracking through the different therapeutic exercises. The disturbance observer controller is incorporated for high precision force control and robustness against exogenous disturbances. Simulation results demonstrate high performance of the proposed wrist rehabilitation device in terms of precise position and force trajectories tracking and robustness against exogenous disturbance as well as patient safety during all therapeutic exercises.

A space crawling robotic bio-paw (SCRBP) enabled by triboelectric sensors for surface identification

With the rapid development of space crawling robotics technology, tactile perception, a significant source for the robot to sense the external environment, has become the preferred solution to gather information in space. Sensors embedded in the robotic end-effector unit can collect and encode the large tactile data, allowing the robot to feel and perceive the real surroundings. Therefore, a space crawling robotic bio-paw (SCRBP) inspired by a cat paw, which performs as a compliant device and can flat the impulse force during the robot’s contact process to the target surface, is proposed in this paper. Meanwhile, a touch-sensing system embedded on SCRBP with self-powered sensors based on the triboelectric nanogenerator (TENG) technology is proposed which can provide the multi-dimensional sensation information in real time. By combining with machine learning (ML), the sensory system can be used for surface identification from the footfall process to the robot’s controller hub. In conclusion, SCRBP device proposed in this paper has obvious advantages in surface information acquisition, space adaptability, power consumption, cost, reliable signal and minimized data. Accordingly, SCRBP system shows fabulous potential in space robotics.

Compliant quasi-zero stiffness device for vibration energy harvesting and isolation

Using a small piezoelectric device to extract energy from low frequency (< 5 Hz) and ultra-low level (< 0.05 g) vibration environments is a very challenging task. The device with quasi-zero stiffness (QZS), widely used in vibration isolation, could be a good candidate for a low frequency energy harvester. However, the conventional QZS devices with complex frames are not very suitable for small-scale harvesters operating in low vibration conditions. To solve these problems, we propose a compact W-shaped compliant mechanism with the direct QZS. Both static and dynamic models have been established to investigate the performance. A compact prototype is fabricated for testing. The experimental results are in good agreement with numerical predictions and demonstrate a good energy harvesting performance under the excitation level below 0.02 g. The normalized power density can even reach 2.3 mW/cm 3 g 2 under the excitation level of 0.007 g at 3.5 Hz. This device can also serve as a compact low-frequency vibration isolator with the transmissibility of − 20 dB at 10 Hz. Overall, this compact QZS device shows a great potential to scalable applications of low-frequency energy harvesting and vibration isolation. Schematic diagram of the energy harvester. • A compact, W-shape compliant system is proposed with a quasi-zero stiffness. • The energy harvester can be used in low frequency environments ( < 5 Hz), and ultra-low vibration (< 0.02 g). • The device with a small size also shows a good performance in the isolation of vibrations at low frequencies.

Towards Unsupervised Rehabilitation: Development of a Portable Compliant Device for Sensorimotor Hand Rehabilitation.

Sensorimotor impairments of the hand after stroke can drastically reduce the ability to perform activities of daily living. Recently, there has been an increased interest in minimally supervised and unsupervised rehabilitation to increase therapy dosage and to complement conventional therapy. Several devices have been developed that are simple to use and portable. Yet, they do not incorporate diversified somatosensory feedback, which has been suggested to promote sensorimotor recovery. Here we present the prototype of a portable one-degree-of-freedom hand trainer based on a novel compliant shell mechanism. Our solution is safe, intuitive, and can be used for various hand sizes. Importantly, it also provides rich sensory feedback through haptic rendering. We complement our device with a rehabilitation game, where we leverage interactive tangible game elements with diverse haptic characteristics to provide somatosensory training and foster recovery.

Design and modeling of a series–parallel compliant device for reliable assembly during a position or angle deviation

Design and modeling of a series–parallel compliant device for reliable assembly during a position or angle deviation

Influence of viscoelastic property of compliance material in achieving successful robotic Peg-In-Hole

Automation of assembly tasks is an inevitable requirement in the manufacturing industries due to the complex design of the components and the requirement for shorter assembly time. In a real-world assembly environment, the misalignments between the mating parts and the necessity for faster insertion due to the time constraints lead to large reactive forces during the insertion. These reactive forces in turn lead to the failure of the insertion process. The successful insertion depends on the handling of these reactive forces using, Remote Centre Compliance (RCC) devices. The selection of the appropriate RCC devices depends on the estimation of stiffness coefficient and damping factors from the dynamic modelling of the assembly process. In order to select the appropriate compliance device and to improve the success rate of the assembly process, this article analyses the contact forces during the dynamic insertion of a single peg component into a hole component, through simulation of the 3-DOF planar robot-aided compliant peg-in-hole assembly process. Rather than considering only the elastic behaviour modelling of compliant devices, this work includes the viscoelastic property of the compliant material in the assembly modelling. An interactive simulation is carried out using the multibody dynamics simulation software MSC Adams/View and MATLAB which is used to precisely compute the contact forces during the insertion phase of the assembly. The results enable one to choose optimal values for lateral and angular stiffness and damping coefficient for a compliant device to achieve a successful assembly task.

Advanced Compliant Anti-Gravity Robot System for Lumbar Stabilization Exercise Using Series Elastic Actuator.

Background: The lumbar stabilization exercise is one of the most recommended treatments in medical professionals for patients suffering from low back pain. However, because lumbar stabilization exercise is calisthenics, it is challenging to perform because of the body load of the elderly, disabled, and patients that lack muscle strength. Additionally, it interferes with the effect of exercise because it can strain parts of the body. Methods: To overcome them, a compliant anti-gravity rehabilitation proto-type device using the Series Elastic Actuator (SEA) was developed previously to provide quantitative assist force to the person, producing similar exercise effects with calisthenics. From an exercise experiment with 20 participants, it caused discomfort to participants during exercise owing to the non-ergonomic design of the previous device. Different muscle activation tendencies were observed between calisthenics and exercise using the device. For advanced technical solutions to clinical needs, which is exercise using the rehabilitation robot to produce a similar effect to calisthenics, the mechanical design of the rehabilitation robot was improved based on the previous device after receiving feedback from clinical trials and static analysis. For the safety of exercise using the robot, a cascade PID-PI controller was used to reduce the influence of friction and disturbance due to the external movement. Results: Surface electromyography(sEMG) signal from lumbar muscles showed desired monotonic reduction ratio and higher similarity results compared to the previous device, which proved the exercise effectiveness using the robot. Conclusion: The proposed robot is considered as a solution to a clinical need of lumbar rehabilitation for the elderly, disabled, and patients.

Modelling on Impact of Building Obstruction for V2I Communication Link in Micro Cellular Environment

In vehicular communication, signal transmission in vehicle-to-infrastructure (V2I) mode typically takes place on highways, urban, suburban and rural environments. The presence of buildings in these environments poses a challenge to model path loss (PL) due to multiple propagation mechanisms such as diffractions and reflections. However, very little attention has been made to address building effects on the performance of V2I communication links in microcell environment. This paper investigates signal propagation characteristics caused by the impact of building under micro-cellular environment whereby the base station or road-side-unit (RSU) is usually located under the rooftop of building to allow communication between RSU and mobile station or on-board-unit (OBU) on the road. The goal of this paper is to validate and discuss available path loss models based on effect of building obstruction towards RSU-OBU links specifically in residential housing area. The channel measurements are conducted based on static line-of-sight (LOS) settings of a real-world environment at 2.4 GHz frequency band using IEEE 802.15.4 XBee S2C compliant device to measure its receive power. The results are demonstrated based on received signal strength indicator (RSSI) and root mean square error (RMSE). The attenuation profile is validated and compared with suitable path loss models to evaluate best fit and most compatible model based on our measurements data and environment. The analysis shows that several V2I path loss models and V2V channel models are applicable to be used as a reference to model in LOS microcell environment with building obstruction. The finding shows that PL Urban yields the best fit V2I path loss model in terms of RMSE when compared to our measurement campaign at 2.4 GHz.

Design and analysis of a compliant 3D printed energy harvester housing for knee implants

Instrumented implants have the potential to detect abnormal loading patterns which could be deleterious to implant longevity, indicating a need for intervention which could reduce the need for more complicated revision surgeries. Reliably powering such devices has been one obstacle preventing widespread usage of instrumented implants in clinical populations. This study presents a 3D-printed titanium interpositional device designed to integrate triboelectric generators (TEGs) into a commercially available total knee replacement (TKR). The device's stiffness, durability, and efficacy as a TEG housing were determined. Surprisingly, the stiffness of the 3D printed prototype was 73% less than what was calculated in a corresponding computational model, and under long-term durability testing failed after approximately 30,000 cycles of simulated gait loading. Under cyclical compressive loading, TEGs embedded in the device were able to generate 10.05 μW of power which is sufficient to run the frontend electronics for a load measurement system. The stiffness discrepancy between the computational and experimental models and the premature fatigue failure are suspected to be a result of internal porosity, unfused material and surface roughness of the 3D printed metal. Further refinements in design and manufacturing of the compliant device are required to improve its durability and TEG power output.

A Stiffness Variable Passive Compliance Device with Reconfigurable Elastic Inner Skeleton and Origami Shell

Devices with variable stiffness are drawing more and more attention with the growing interests of human-robot interaction, wearable robotics, rehabilitation robotics, etc. In this paper, the authors report on the design, analysis and experiments of a stiffness variable passive compliant device whose structure is a combination of a reconfigurable elastic inner skeleton and an origami shell. The main concept of the reconfigurable skeleton is to have two elastic trapezoid four-bar linkages arranged in orthogonal. The stiffness variation generates from the passive deflection of the elastic limbs and is realized by actively switching the arrangement of the leaf springs and the passive joints in a fast, simple and straightforward manner. The kinetostatics and the compliance of the device are analyzed based on an efficient approach to the large deflection problem of the elastic links. A prototype is fabricated to conduct experiments for the assessment of the proposed concept. The results show that the prototype possesses relatively low stiffness under the compliant status and high stiffness under the stiff status with a status switching speed around 80 ms.

Conformable polyimide-based μECoGs: Bringing the electrodes closer to the signal source

Structural biocompatibility is a fundamental requirement for chronically stable bioelectronic devices. Newest neurotechnologies are increasingly focused on minimizing the foreign body response through the development of devices that match the mechanical properties of the implanted tissue and mimic its surface composition, often compromising on their robustness. In this study, an analytical approach is proposed to determine the threshold of conformability for polyimide-based electrocorticography devices. A finite element model was used to quantify the depression of the cortex following the application of devices mechanically above or below conformability threshold. Findings were validated in vivo on rat animal models. Impedance measurements were performed for 40 days after implantation to monitor the status of the biotic/abiotic interface with both conformable and non-conformable implants. Multi-unit activity was then recorded for 12 weeks after implantation using the most compliant device type. It can therefore be concluded that conformability is an essential prerequisite for steady and reliable implants which does not only depend on the Young's modulus of the device material: it strongly relies on the relation between tissue curvature at the implantation site and corresponding device's thickness and geometry, which eventually define the moment of inertia and the interactions at the material-tissue interface.

4242 Evaluating the effect of a compliant stent-graft prototype on effective stiffness in a cadaveric aorta

OBJECTIVES/GOALS: High aortic stiffness is associated with increased cardiovascular morbidity and mortality. The purpose of this work is to demonstrate the potential of our compliant stent-graft design to therapeutically increase aortic compliance over a standard aortic stent-graft. METHODS/STUDY POPULATION: The aorta from a human cadaver will be excised and placed into a pulse duplicator circuit. The stiffness of the system will be estimated using the pulse wave velocity (PWV), which will be calculated using the time delay between pressure measurements at proximal and distal locations in the system. Baseline measurements with the unstented aorta will be compared to two cases: (1) with a standard stent-graft placed, and (2) with our compliant stent-graft prototype in the descending thoracic aorta. PWV is calculated as the distance between the pressure sensors divided by the time delay. Faster PWV is associated with a stiffer vessel, or lower aortic compliance. RESULTS/ANTICIPATED RESULTS: Prior work in vitro showed that the compliant stent-graft reduced peak and pulse pressures compared a standard, rigid stent-graft. We also expect the compliant device to exhibit lower PWV compared to a rigid stent-graft. Depending on the aortic tissue stiffness, the compliant stent-graft could raise or lower PWV compared to no stent. Mean pressure in the compliant case is likely to be slightly higher than the other two cases because the compliant stent-graft’s narrower lumen increases flow resistance. Although mean pressure will be higher, peak pressure should be lower than in the standard stent-graft because the added compliance decreases overall pressure swing between systole and diastole. DISCUSSION/SIGNIFICANCE OF IMPACT: Lower PWV in the compliant stent-graft over the standard stent-graft will indicate its potential to therapeutically lower aortic stiffness in patients needing aortic stenting. Positive outcomes from this study will be a step toward the eventual translation of a compliant stent-graft to clinical use.

An open-source solution to performance portability for Summit and Sierra supercomputers

Programming models that use a higher level of abstraction to express parallelism can target both CPUs and any attached devices, alleviating the maintainability and portability concerns facing today's heterogenous systems. This article describes the design, implementation, and delivery of a compliant OpenMP device offloading implementation for IBM-NVIDIA heterogeneous servers composing the Summit and Sierra supercomputers in the mainline open-source Clang/LLVM compiler and OpenMP runtime projects. From a performance perspective, reconciling the GPU programming model, best suited for massively parallel workloads, with the generality of the OpenMP model was a significant challenge. To achieve both high performance and full portability, we map high-level programming patterns to fine-tuned code generation schemes and customized runtimes that preserve the OpenMP semantics. In the compiler, we implement a low-overhead single-program multiple-data scheme that leverages the GPU native execution model and a fallback scheme to support the generality of OpenMP. Modular design enables the implementation to be extended with new schemes for frequently occurring patterns. Our implementation relies on key optimizations: sharing data among threads, leveraging unified memory, aggressive inlining of runtime calls, memory coalescing, and runtime simplification. We show that for commonly used patterns, performance on the Summit and Sierra GPUs matches that of hand-written native CUDA code.

005 Impact of Continuous Positive Airway Pressure on the Atrial Substrate in Patients With Obstructive Sleep Apnoea and Atrial Fibrillation: The SLEEP-AF Substrate Sub-Study

Obstructive sleep apnoea (OSA) is associated with an increasingly remodeled atrial substrate in atrial fibrillation (AF). Management of OSA has also been linked with improved management outcomes of AF. However, the impact of OSA management on the electrophysiologic atrial substrate has not been evaluated. To determine the impact of OSA management on the atrial substrate in AF. We recruited 24 consecutive patients having catheter ablation for AF with at least moderate OSA (AHI ≥15). Participants were randomised in a 1:1 ratio to receive continuous positive airway pressure (CPAP) or no therapy. At baseline, all participants underwent invasive electrophysiologic study comprising high density right atrial mapping and evaluation of effective refractory periods (ERP). After minimum of 6 months, the electrophysiologic protocol was repeated. Data was blinded and analysed offline. Outcome variables were atrial voltage (mV), conduction velocity (m/s), atrial surface area <1.5mV (%), atrial surface area <0.5mV (%), complex points (%) and atrial ERP (ms). There were no differences in baseline characteristics between groups and electrophysiologic parameters were comparable at baseline. Participants having CPAP were highly compliant (device usage: 79±19%, usage time: 268±91mins) resulting in significant AHI reduction (mean reduction: 31±23). There were no differences in blood pressure or body mass index between groups over time. The table presents data showing that CPAP results in marked reverse atrial remodelling. CPAP therapy results in reversal of atrial remodelling, providing mechanistic evidence advocating for management of OSA in AF.

An ISO/IEEE 11073 Standardized Digital Twin Framework for Health and Well-Being in Smart Cities

The use of the digital twin has been quickly adopted in industry in recent years and continues to gain momentum. The recent redefinition of the digital twin from the digital replica of a physical asset to the replica of a living or nonliving entity has increased its potential. The digital twin not only disrupts industrial processes, but also expands the domain of health and well-being towards fostering smart healthcare services in smart cities. In this paper, we propose an ISO/IEEE 11073 standardized digital twin framework architecture for health and well-being. This framework encompasses the process of data collection from personal health devices, the analysis of this data, and conveying the feedback to the user in a loop cycle. The framework proposes a solution to include not only X73 compliant devices, but also noncompliant health devices, by interfacing them with an X73 wrapper module as we explain in this paper. Besides, we propose a configurable X73 mobile application, designed to work with any X73 compliant device. We designed and implemented the proposed framework, and the X73 mobile app, and conducted an experiment as a proof of concept of the digital twin in the domain of health and well-being in smart cities. The experiment shows promising results and the potential of benefiting from the proposed framework, by gaining insights on the health and well-being of individuals, and providing feedback to the individual and caregiver.