Knee Bending Research Articles

Tracking Control for FES Alternate Knee Bending and Stretching Trike With Electric Motor Assistance

This paper deals with a new control method for functional electrical stimulation (FES) alternate knee bending and stretching trike with electric motor assistance. While FES-cycling is known as a beneficial exercise for people with movement disorders, a paraplegia patient could not pedal smoothly by applying the previous method. One of the possible reasons is that there is a dead point in the pedaling motion intrinsically. To overcome this drawback, we developed a trike system which can be moved by alternating knee bending and stretching of the left and right legs for paraplegia patients. Electric motor assistance plays an important role to recover deceleration of the trike when switching between flexion and extension. Stability of the developed control law is analyzed through Lyapunov-based methods.

Design and biomechanical analysis of a self-force source power-assisted knee orthotics actuated by liquid spring

A micro silicone oil liquid spring was designed and manufactured in this article. The performance of the liquid spring was studied by simulation analysis and mechanical test. A self-force source power-assisted knee orthosis was designed based on the liquid spring. This power-assisted knee orthosis can convert the kinetic energy of knee flexion into the elastic potential energy of liquid spring for storage, and release elastic potential energy to generate assisted torque which drives the knee joint for extension. The results showed that the average maximum reset force of the liquid spring was 1 240 N, and the average maximum assisted torque for the knee joint was 29.8 N·m. A musculoskeletal multibody dynamic model was used to analyze the biomechanical effect of the knee orthosis on the joint during knee bending (90°knee flexion). The results showed that the power-assisted knee orthosis could effectively reduce the biomechanical load of the knee joint for the user with a body weight of 80 kg. The maximum forces of the femoral-tibial joint force, patellar-femoral joint force, and quadriceps-ligament force were reduced by 24.5%, 23.8%, and 21.2%, respectively. The power-assisted knee orthosis designed in this article provides sufficient assisted torque for the knee joint. It lays a foundation for the subsequent commercial application due to its small size and lightweight.

Simultaneously Stretchable and Compressible Flexible Strain Sensors Based on Carbon Nanotube Composites for Motion Monitoring and Human–Computer Interactions

Simultaneously stretchable and compressible flexible strain sensors are highly desired in many advanced applications including the wearable field. However, the fabrication of such dual-function sensors with a wide sensing range is still challenging. In this work, a simultaneously stretchable and compressible foam strain sensor was fabricated by skillfully introducing oriented pores into the highly stretchable elastic composite based on carbon nanotubes and poly(styrene-b-ethylene–butylene-b-styrene) (SEBS) by a freeze-drying method, in which cyclohexane was employed as the freeze-drying solvent. The high stretchability of SEBS and the abundant compressible space imparted by the pores endowed the resultant flexible foam sensor with highly stretchable (250%) and compressive (−50%) characteristics simultaneously. Thanks to the outstanding flexible features, the foam sensor enabled simultaneous monitoring of multiple human movements, such as bidirectional wrist bending, knee bending, foot stepping, and so forth. The foam sensor could encrypt human gesture signals into electrical signals and transmit them to the machine to realize the human–computer interaction, which could greatly broaden the application prospect of flexible strain sensors in the field of intelligent sensing.

Quality Analysis of Taekwondo Side Kick

<p>目的：本文針對跆拳道品勢側踢質量分析，探討品勢側踢關鍵特徵與專業教練評分之相關性以及其重要程度排序，並以此跆拳道側踢動作關鍵特徵，提供教練及選手客觀之依據，將有助於跆拳道品勢技能足技動作競技水準之提升。方法：本研究以臺北市立龍山國民中學以及國立臺灣師範大學品勢運動員為研究對象，共計10人，透過錄製運動員之側踢影像，研擬品勢側踢關鍵計有七項特徵，並分析品勢運動員在其側踢過程中，與教練評分之相關性和重要程度排序，最終針對結果進行整理及系統性分析。結果：共探討七項品勢側踢關鍵特徵，分析其與專業教練評分之相關性，根據相關性關鍵特徵重要程度依序為夾膝時與軀幹之夾角、收腳過程的平均速度、踢擊最高點至開始收腳的時間、踢擊最高點之持續時間、夾膝完成至踢擊最高點的加速過程、支撐腳腳根與腳尖之夾角、收腳過程軀幹與支撐腳之夾角。結論：一、研究顯示側踢品質主要以夾膝時與軀幹之夾角判定，與動作評分呈現高度相關性。二、在側踢關鍵特徵中，表明(1)當踢擊最高點至開始收腳的時間越長(2)收腳過程中，軀幹與支撐腳之夾角越小(3)收腳過程的平均速度越快(4)夾膝時與軀幹之夾角越小，教練對於側踢表現之評分越高。</p> <p> </p><p>Purpose: This paper examines the quality of the Side Kick in Taekwondo and investigates the correlation between the key characteristics of the Side Kick and the professional coach’s rating, as well as the ranking of their importance. Providing coaches and players with an objective basis from our analysis will help to raise the level of Poomsae competition in foot techniques. Method: In this study, a total of 10 athletes from Taipei Longshan National High School and National Taiwan Normal University participated as the subjects. Using the videos of the athletes’ side kicks, we analyzed the importance of the judges’ ratings during the side kick stance and provided a reference for coaches and athletes in training or competition. Finally, the results were collected and systematically analyzed. Results: Seven key features of the Side Kick were analyzed, in descending order of importance, as follows: the angle between the bent knee and the torso, the average speed from the recovery process, the time between the highest point of the kick and the start of the leg retraction, the duration of the highest point of the kick, the acceleration between the completion of the knee clinch and the highest point of the kick, the angle between the heel and tiptoe of the supporting foot, and the angle between the torso and the supporting foot during the recovery process. Conclusion: 1. Research has shown that Taekwondo instructors mainly judge the quality of a Side Kick by the angle between the knee and the torso, which shows a high correlation with movement scores. 2. Among the seven key characteristics of the Side Kick, it shows that the following four characteristics will result in a higher score of the performance for the Side Kick: (1) the longer time between the highest point of the kick and the start of the recovery; (2) the smaller the angle between the torso and the supporting foot; (3) the faster the average speed of the recovery; and (4) the smaller the angle between the torso and the knee during the recovery.</p> <p> </p>

Power and Play

Power and Play

An Ergonomic Design Process of the Functional Clothing for Yoga Sports

Abstract Reports attribute many physical, psychological and mental benefits to yoga sports. However, when it comes to actual research, yoga clothing has not attracted the same level of attention. The aim of this study, which involved a questionnaire survey, clothing development and clothing performance evaluation, is to propose an ergonomic design process for the design of yoga functional clothing. Results showed that textile material was rated as the most important factor for yoga clothing. The shoulder and the waist-belly regions were considered as the most important areas for yoga clothing. The newly designed clothing prototype was observed to subject significantly lower pressure to the waist under the forward bending pose (p<0.05), but with significantly higher pressure on the buttocks at the posture of the deep knee bending pose (p<0.05). It also resulted in a lower change rate of clothing vertical displacement, especially at the shoulder and waist regions. The newly designed prototype was rated with a significantly lower tightening sensation and pulling sensation during the deep knee bending posture (p<0.05). Results indicate that proper design of yoga clothing structure and selection of fabric material could reduce clothing deformation, pressure on the skin and improve subjective wearing sensations.

3D printable and stretchable PVA‐PAAm dual network hydrogel with conductivities for wearable sensors

AbstractConductive hydrogel has broad potential applications in wearable sensors and flexible electronic devices. However, due to the complicated and restrictive mold‐casting process, the manufacture of hydrogel‐based sensors is still facing great challenges. In this paper, we adopt direct inkjet printing (DIW) technology to fabricate three‐dimensional structures of chemically and physically cross‐linked hydrogels by integrating fumed silica as a rheological modifier into crosslinked poly(vinyl alcohol)/poly(acrylamide) (PVA/PAAm) network. Fumed silica not only enables hydrogels with excellent rheological properties, but also provides more hydrogen bond crosslinking sites, further improving mechanical properties. Meanwhile, calcium chloride (CaCl2) is supplemented to construct conductive channels in the hydrogel, which powers the hydrogel with good conductivity and strain sensitivity. The sensor assembled from 3D printed hydrogel shows cycle stability and accurate recognition ability in detecting mechanical deformation and various human movements (for example knee bending and frown). This work extends the application of 3D printing hydrogel in the field of wearable devices.

Intrinsically adhesive, conductive organohydrogel with high stretchable, moisture retention, anti-freezing and healable properties for monitoring of human motions and electrocardiogram

A novel self-adhesive conductive organohydrogel without catechol adhesive components is developed for long-term, continuous monitoring of human motions and electrocardiogram. The organohydrogel is achieved by covalent cross-linking polymerization of acrylamide, N-acryloylglycinamide, and reduced graphene oxide, followed by soaking into ethylene glycol-water mixture. The organohydrogel exhibits intrinsic adhesion to various substances, excellent healing ability of nearly 100% conductivity repair rate, long-lasting moisture retention (about 30 days), extreme temperature tolerance (–20–60 °C), stable conductivity and extraordinary mechanical properties with a maximum tensile strength of 300 kPa, high stretchability over 1700%, compressive stress over 5 MPa. This organohydrogel can adhere to human skin without other fixture for human motions monitoring, such as the bending of wrist, finger, elbow and knee, and throat actions. Moreover, the organohydrogel can achieve long-term, continuous monitoring of human ECG signals in various daily activities, such as a night of sleep, standing, walking, performing leg curls and leg presses, and using an elliptical machine. This research offers a new strategy to develop self-adhesive conductive organohydrogel for long-term, continuous, and imperceptible monitoring of human health signals.

Patient-reported impairment following TKA is reduced when a computationally simulated predicted ideal alignment is achieved

PurposeJoint dynamics following Total Knee Arthroplasty (TKA) may influence patient-reported outcome. Simulations allow many knee alignment approaches to a single patient to be considered prior to surgery. The simulated kinematics can be matched to patient-reported outcome to predict kinematic patterns most likely to give the best outcome. This study aims to validate one such previously developed algorithm based on a simulated deep knee bend (the Dynamic Knee Score, DKS).Methods1074 TKA patients with pre- and post-operative Computerised Tomography (CT) scans and 12-month post-operative Knee Injury and Osteoarthritis Outcomes (KOOS) Scores were identified from the 360 Med Care Joint Registry. Landmarking and registration of implant position was performed on all CT scans, and each of the achieved TKAs was computationally simulated and received a predictive outcome score from the DKS. In addition, a set of potential alternative surgical plans which might have been followed were simulated. Comparison of patient-reported issues and DKS score was evaluated in a counter-factual study design.ResultsPatient-reported impairment with the knee catching and squatting was shown to be 30% lower (p = 0.005) and 22% lower (p = 0.026) in patients where the best possible DKS result was the one surgically achieved. Similar findings were found relating attainment of the best tibial slope and posterior femoral resection DKS plans to patient-reported difficulty straightening the knee (40% less likely, p < 0.001) and descending stairs (35% less likely, p = 0.006).ConclusionThe DKS has been shown to correlate with presence of patient-reported impairments post-TKA and the resultant algorithm can be applied in a pre-operative planning setting. Outcome optimization in the future may come from patient-specific selection of an alignment strategy and simulations may be a technological enabler of this trend.Level of evidence.III (Retrospective Cohort Study).

Sustainable, bio-based conductive materials from peanut waste for flexible electronics and tunable piezoresistive strain sensors

Sustainable engineering applications are of great significance in materials science because of limited natural resources. This study presents a sustainable, bio-based approach for the fabrication of flexible electronics and sensors by using peanut shell and skin as the precursors for conductive carbon-based fillers. Carbonized samples showed differences in terms of morphological, structural, and electrical properties. While peanut shell-based carbon showed higher crystallinity and morphology with multiple channels; peanut skin-based carbon showed stacked, layered morphology with smaller particle size. Elastic modulus of the samples increased, tensile strength, and tensile strain values were decreased for both composite sets. The electrical conductivity of the samples prepared by carbon from peanut shell showed lower percolation concentration. Both composites showed piezoresistive response under cycling loading/unloading and tunable piezoresistive sensors were shown to be sensitive to human motions including horizontal and vertical elbow movement and back and forth knee bending and squatting.

Energy Harvesting and Sensing Integrated Woven Structure Kneepad Based on Triboelectric Nanogenerators

AbstractTriboelectric nanogenerators (TENGs) are extensively studied because of their great potential in energy harvesting and sensing. Traditional chemical batteries cannot meet the requirements of wearable electronic products because of their inherent limitations such as large weight, large size, limited endurance, and limited lifespan. To address the issue, the self‐powered energy harvester has attracted considerable interest among researchers. Here, the woven structure TENG consists of flexible silicone mixed with polyvinylidene fluoride as dielectric layers, silver fabric, and conductive tape as electrodes. The electrical output performance of the pattern structure processed by tip design is nearly three times higher. The whole TENG and flexible printed circuit board are encapsulated by polydimethylsiloxane film, reducing inconvenient, and discomfort sensation during wearing. The woven structure TENG can not only harvest energy to power wearable electronic devices but also be used to recognize human motion as the waveforms changing when people are in different states. Taking the knee bending angle data as an example to conduct machine learning, it is able to classify different states of human motion. This work extends the application of the woven TENG as an integrated device for sensing and energy harvesting.

WEARABLE ROBOTIC DEVICE DESIGNED TO IMPROVE MUSCULAR STRENGTH IN CEREBRALPALSY

Cerebral palsy has traditionally been thought of as a mobility and gait issue caused by a non-progressive damage to the developing mind. While indicative usual symptoms may occur at an earlier age, the characteristics of this entity develop over time, and the particular cerebral palsy condition may not be recognized until the child is between the ages of 3 and 5. Crouch walk, and severe knee bending when moving, is one of the most prevalent indicators of cerebral palsy. Leg splints, muscle damage, physical therapy, and leg surgeries can all assist children with cerebral palsy enhance their walking skills. Current gait trainers are primarily concerned with managing full joint trajectories, avoiding postural control, and tailoring therapy to a specific patient. Robotic exoskeletons used for adult with total paralysis, this one did not walk for the participant. They used their muscle to walk and assisted robot. The hope is that the device which is use will strengthen a child’s muscle to improve unassisted walking. The use of the CP Walker, a revolutionary mechanical system for children with spastic palsy.

Highly stretchable and self-adhesive ionically cross-linked double-network conductive hydrogel sensor for electronic skin

Flexible, wearable sensors are attracting considerable interest because of their potential applications for human–machine interfaces, human-activity monitoring, and personal healthcare diagnosis. Hydrogels are promising material candidates for the wearable sensors due to their biocompatibility, high water content, structural similarity to natural soft tissues, and resemblance to extracellular matrix. However, the wearable hydrogel sensors have the limitations of poor adhesion and low electroconductivity. Herein, a healable, adhesive, and conductive wearable hydrogel sensor was designed by incorporating polydopamine decorated carbon nanotubes (PDA-CNTs) and FeCl3 into acrylamide-co-acrylic acid polymer (P(AAm-co-AAc)) matrix, forming a catechol/P(AAm-co-AAc)/Fe3+ double-network hydrogel sensor. The hydrogel sensor displayed good stretchability and high sensitivity with a gauge factor of 44.2 at 700% strain. And it exhibited fast and repeatable self-healing ability (healed completely after 60 s at room temperature without any external assistance). The resistance of the hydrogel showed repeatable and periodic variations during multiple cyclic stretching (1000 cycles), demonstrating good stability of this hydrogel sensor. The PDA-CNT hydrogel also showed strong adhesiveness to various substrates, including glass, metal, and plastic. When adhered onto a human body, the hydrogel was able to accurately monitor various motions, such as the bending of finger, wrist, elbow, and knee. These results showed the hydrogel sensor’s sensitivity and repeatability for detecting human motions. The healable, adhesive, conductive hydrogel is a promising material for wearable sensors to monitor human motion and can be used for personal healthcare diagnosis and therapy.

Using Long-Duration Static Stretch Training to Counteract Strength and Flexibility Deficits in Moderately Trained Participants.

Many sports injuries result in surgery and prolonged periods of immobilization, which may lead to significant atrophy accompanied by loss of maximal strength and range of motion and, therefore, a weak-leg/strong-leg ratio (as an imbalance index ∆ ) lower than 1. Consequently, there are common rehabilitation programs that aim to enhance maximal strength, muscle thickness and flexibility; however, the literature demonstrates existing strength imbalances after weeks of rehabilitation. Since no study has previously been conducted to investigate the effects of long-duration static stretch training to treat muscular imbalances, the present research aims to determine the possibility of counteracting imbalances in maximal strength and range of motion. Thirty-nine athletic participants with significant calf muscle imbalances in maximal strength and range of motion were divided into an intervention group (one-hour daily plantar flexors static stretching of the weaker leg for six weeks) and a control group to evaluate the effects on maximal strength and range of motion with extended and bent knee joint. Results show significant increases in maximal strength (d = 0.84–1.61, p < 0.001–0.005) and range of motion (d = 0.92–1.49, p < 0.001–0.002) following six weeks of static stretching. Group * time effects (p < 0.001–0.004, η² = 0.22–0.55) revealed ∆ changes in the intervention group from 0.87 to 1.03 for maximal strength and from 0.92 to 1.11 in range of motion. The results provide evidence for the use of six weeks of daily, one hour stretching to counteract muscular imbalances. Related research in clinical settings after surgery is suggested.

How does asymmetric tibial insert affect tibiofemoral kinematics and contact stresses in total knee Arthroplasty?

BackgroundAsymmetric tibial insert design is expected to restore normal knee kinematics better than symmetric design. A tri-condylar implant has asymmetric and symmetric tibial inserts with a ball-and-socket joint to replace the post-cam mechanism. The purpose of this study was to compare the knee kinematics of the two designs and to measure tibiofemoral contact stresses, including that of the ball-and-socket joint. MethodsUsing a computer simulation, the anteroposterior position and axial rotation of the femoral component were simulated during a weight-bearing deep knee bend for six validated models. Contact forces were simultaneously simulated in the medial, lateral, and ball-and-socket compartments. The relative position and the magnitude and direction of each contact force were applied to aforce/displacement control knee simulator. The contact stresses were measured individually using a pressure sensor. ResultsThe asymmetric tibial insert demonstrated a more posterior position of the femoral component in the lateral compartment during the entire range of motion and greater external rotation of the femoral component, compared to the symmetrical tibial insert. The mean peak contact stress of the medial and lateral compartments was < 9 Mpa, with no significant differences between the two designs except at 0°. The contact stress of the ball-and-socket joint was < 5 MPa. ConclusionsAsymmetry of the tibial insert shows significant kinematic difference and has little influence on the peak contact stress, which is considerably lower than the yield strength of polyethylene. The asymmetric tibial insert can lead to clinical benefits owing to its kinematic and kinetic properties.

Conductive, self-healing, and antibacterial Ag/MXene-PVA hydrogel as wearable skin-like sensors.

The rapid development of flexible electronic technology has led to the in-depth study of flexible wearable sensors to achieve accurate sensing under different external stimuli. However, it is still a huge challenge to develop hydrogel-based wearable skin-like sensors with super ductility, high sensitivity, and self-healing properties. Herein, the Ti3C2 type of MXene was synthesized, and the Ag/MXene nanocomplexes were incorporated into polyvinyl alcohol-borax matrix to construct a novel composite hydrogel as the multifunctional nanofillers, which could bring both improved properties and novel functionalities. The Ag/MXene-Poly (vinyl alcohol) (PVA) hydrogel displayed integrated merits of highly strain sensitive (GF = 3.26), self-healing (within 10 min, 91% healing efficiency), and excellent antibacterial activity. The hydrogel could be assembled into a wearable skin-like sensor to monitor human movement, including large deformations (finger, elbow, wrist, and knee bending) and tiny deformations (mouth's movement and throat vocalization) in real time. Therefore, this work shed a new light on the development of flexible wearable skin-like sensors for the personalized healthcare monitoring, human-machine interfaces, and artificial intelligence.

Wide-Range Flexible Capacitive Pressure Sensors Based on Dielectrics with Various Porosity.

Wide-range flexible pressure sensors are in difficulty in research while in demand in application. In this paper, a wide-range capacitive flexible pressure sensor is developed with the foaming agent ammonium bicarbonate (NH4HCO3). By controlling the concentration of NH4HCO3 doped in the polydimethylsiloxane (PDMS) and repeating the curing process, pressure-sensitive dielectrics with various porosity are fabricated to expand the detection range of the capacitive pressure sensor. The shape and the size of each dielectric is defined by the 3D printed mold. To improve the dielectric property of the dielectric, a 1% weight ratio of multi-walled carbon nanotubes (MWCNTs) are doped into PDMS liquid. Besides that, a 5% weight ratio of MWCNTs is dispersed into deionized water and then coated on the electrodes to improve the contact state between copper electrodes and the dielectric. The laminated dielectric layer and two electrodes are assembled and tested. In order to verify the effectiveness of this design, some reference devices are prepared, such as sensors based on the dielectric with uniform porosity and a sensor with common copper electrodes. According to the testing results of these sensors, it can be seen that the sensor based on the dielectric with various porosity has higher sensitivity and a wider pressure detection range, which can detect the pressure range from 0 kPa to 1200 kPa and is extended to 300 kPa compared with the dielectric with uniform porosity. Finally, the sensor is applied to the fingerprint, finger joint, and knee bending test. The results show that the sensor has the potential to be applied to human motion detection.

Interpretation of natural tibio-femoral kinematics critically depends upon the kinematic analysis approach: A survey and comparison of methodologies

While there is general agreement on the transverse plane knee joint motion for loaded flexion activities, its kinematics during functional movements such as level walking are discussed more controversially. One possible cause of this controversy could originate from the interpretation of kinematics based on different analysis approaches. In order to understand the impact of these approaches on the interpretation of tibio-femoral motion, a set of dynamic videofluoroscopy data presenting continuous knee bending and complete cycles of walking in ten subjects was analysed using six different kinematic analysis approaches. Use of a functional flexion axis resulted in significantly smaller ranges of condylar translation compared to anatomical axes and contact approaches. All contact points were located significantly more anteriorly than the femur fixed axes after 70° of flexion, but also during the early/mid stance and late swing phases of walking. Overall, a central to medial transverse plane centre of rotation was found for both activities using all six kinematic analysis approaches, although individual subjects exhibited lateral centres of rotation using certain approaches. The results of this study clearly show that deviations from the true functional axis of rotation result in kinematic crosstalk, suggesting that functional axes should be reported in preference to anatomical axes. Contact approaches, on the other hand, can present additional information on the local tibio-femoral contact conditions. To allow a more standardised comparison and interpretation of tibio-femoral kinematics, results should therefore be reported using at least a functionally determined axis and possibly also a contact point approach.

Knee Bending Prevention System for Robotic Knee Prosthesis Using Finite State Machine

Knee Bending Prevention System for Robotic Knee Prosthesis Using Finite State Machine

In vivo kinematic comparison of medial pivot total knee arthroplasty in weight-bearing and non-weight-bearing deep knee bending

BackgroundThis study aimed to determine the kinematics of medial pivot total knee arthroplasty by comparing weight-bearing and non-weight-bearing deep knee bending and to evaluate the effect of the weight-bearing state on the kinematics. MethodsThe kinematics of 19 knees were investigated under fluoroscopy during squatting (weight-bearing) and active-assisted knee bending (non-weight-bearing) using two- to three-dimensional registration technique. Accordingly, range of motion, anteroposterior translation for the medial and lateral low contact points, axial rotation of the femoral component relative to the tibial component and kinematic pathway were evaluated. FindingsThere was no difference in range of motion between the two states. The medial anteroposterior translation showed no significant movement with no anterior translation in both the weight-bearing and non-weight-bearing from 0° to 90° of flexion. Regarding the lateral anteroposterior translation, a posterior translation was observed during weight-bearing, whereas a slight anterior translation from 0° to 30° of flexion and subsequent posterior translation were found in the non-weight-bearing. Femoral external rotation was observed in the weight-bearing, whereas femoral internal rotation was seen from 0° to 30° of flexion and subsequent femoral external rotation was observed in the non-weight-bearing. The kinematic pathway showed medial pivot motion and subsequent bicondylar rollback in the weight-bearing, whereas only medial pivot motion was observed in the non-weight-bearing. InterpretationThe medial anteroposterior translation of the femur during deep knee bending showed no anterior motion in the two states. The lateral anteroposterior translation and femoral rotation were different in the mid-flexion range between the two states.