Design and Research of Wearable Fall Protection Device for the Elderly / 中国医疗器械杂志

A protective device was designed that can be worn on the elderly, which consists of protective airbag, control box and protective mechanism. The combined acceleration, combined angular velocity and human posture angle are selected as the parameters to determine the fall, and the threshold algorithm and SVM algorithm are used to detect the fall. The protective mechanism is an inflatable device based on CO2 compressed air cylinder, and the equal-width cam structure is applied to its transmission part to improve the puncture efficiency of the compressed gas cylinder. A fall experiment was designed to obtain the combined acceleration and angular velocity eigenvalues of fall actions (forward fall, backward fall and lateral fall) and daily activities (sitting-standing, walking, jogging and walking up and down stairs), showing that the specificity and sensitivity of the protection module reached 92.1% and 84.4% respectively, which verified the feasibility of the fall protection device.

Evaluation method of dynamic postural stability for functional ankle instability based on acceleration signals / 中国康复理论与实践

ObjectiveTo compare the retest reliability and discriminant validity of dynamic postural stability indices for functional ankle instability (FAI) obtained by different algorithms based on acceleration signals at different positions of human body. MethodsFrom April to June, 2021, 21 subjects with unilateral FAI and 21 subjects with normal ankle were recruited. Three inertial sensors were attached to the waist points, knee and ankle positions. The ground reaction force (GRF) and kinematics data of the subjects in multi-direction single leg landing test were collected synchronously by 3D force plate and inertial sensors. The unbounded third order polynomial (UTOP) fitting method was used to calculate the stability time, and the root mean square was used to caculate the stability index. ResultsMost of the indicators calculated based on acceleration signal correlated with that based on GRF with low coefficient (|r| = 0.116 to 0.368, P < 0.05). The stability time and stability index based on the acceleration signals of different positions of human body showed low to high retest reliability (CMC 0.30 to 0.91). For the females, among the stability time based on acceleration signal, eleven indexes achieved average to very high discriminant validity (AUC = 0.702 to 0.942, P < 0.05); eight of the stability indexes reached general level of discriminant validity (AUC = 0.717 to 0.782, P < 0.05). No algorithms achieved good discriminant effect in male subjects. ConclusionBased on the acceleration signal of waist point in single-leg landing stability test, the stability time calculated by UTOP algorithm can evaluate the dynamic postural stability of female FAI patients with high discriminant validity and medium to high retest reliability.

Knee Joint Moment Estimation During Walking via Wearable Inertial Sensor Network / 医用生物力学

Objective To estimate knee adduction moment (KAM) and knee flexion moment (KFM) under different gait test conditions via an inertial sensor network (ISN). Methods Twelve healthy young male subjects wore eight inertial sensors (located in the trunk, pelvis, both thighs, both shanks, both feet) and walked under different test conditions (changing foot progression angle, trunk sway angle, step width and walking speed). An ISN was used to extract biomechanical features as the input of recurrent neural network (RNN), so as to estimate the KAM and KFM. Results The overall KAM estimation accuracy: relative root mean square error (rRMSE) was 8.54% and r=0.84. The overall KFM estimation accuracy was rRMSE=6.40% and r=0.94. Conclusions The model can be used as the basis for load estimation of knee joints out of the lab and its potential application includes gait training and rehabilitation assessment after knee surgery.

Utilização de sensores inerciais no teste timed up and go: uma revisão narrativa / Use of inertial sensors in the timed up and go test: a narrative review

O teste funcional Timed Up and Go (TUG) é amplamente utilizado para avaliar o risco de queda, através do equilíbrio e mobilidade, por ser de fácil aplicação e boa reprodutibilidade na prática clínica. Porém, o TUG ainda possui algumas limitações, pois se concentra no tempo total em que o teste é realizado. Uma proposta de avaliação é através da utilização de sensores inerciais, baseados na tecnologia de sistemas microeletromecânicos, e vem sendo muito utilizados para análise do movimento humano. Logo, o objetivo desse estudo foi realizar uma revisão narrativa sobre o uso dos sensores inerciais nas medidas temporais e cinemáticas do TUG e suas subfases. Metodologia: Essa revisão narrativa foi realizada nas bases de dados PubMed, CENTRAL, BVS e PEDro, por meio do vocabulário MeSH entre o período de maio a junho de 2020. Os critérios de inclusão foram estudos que utilizaram sensores inerciais para avaliação de medidas temporais e cinemáticas do TUG e suas subfases. Resultados: Foram incluídos 11 artigos de um total de 2305 achados. Desses, 5 utilizaram os sensores de smartphones. Não houve padronização em relação à quantidade utilizada, nem à fixação e posicionamento. Os sensores conseguiram mostrar diferenças no TUG e suas subfases nas medidas temporais e cinemáticas nos diferentes grupos avaliados. Considerações Finais: Sensores inerciais são capazes de avaliar medidas temporais e cinemáticas do TUG e de suas subfases, mostrando serem ferramentas confiáveis. Entretanto, mesmo obtendo resultados satisfatórios, necessita-se de mais estudos abrangendo uma população maior.

The Timed Up and Go (TUG) functional test is widely used to assess the risk of falling through balance and mobility since it is easy to apply and presents good reproducibility in clinical practice. However, the TUG test still has some limitations, as it focuses on the total time the test is performed. A proposal for evaluation is the use of inertial sensors, based on the microelectromechanical system technology, which has been widely used for the analysis of human movement. Therefore, the objective of this study was to carry out a narrative review on the use of inertial sensors in the temporal and kinematic measurements of TUG and its subphases. Methodology: This narrative review was carried out in the PubMed, CENTRAL, BVS, and PEDro databases using the MeSH vocabulary between the period of May to June 2020. The inclusion criteria were studies using inertial sensors to evaluate temporal and kinematic measurements of the TUG and its subphases. Results: A total of 11 articles were selected from 2305 hits. From these, five (5) used smartphone sensors. There was no standardization regarding the quantity used, nor their fixation and positioning. The sensors were able to show differences in the TUG and its subphases in the temporal and kinematic measurements in the different groups evaluated. Final Considerations: Inertial sensors are capable of evaluating temporal and kinematic measurements of the TUG and its subphases, showing that they are reliable tools. Nevertheless, although satisfactory results were obtained, further studies are needed covering a larger population.

A simulating fracture manual reduction training system based on virtual reality technology / 军事医学

Objective To design a virtual reality(VR) system for fracture reduction training using manikin technology.Methods The real-time posture information of the manikin skeleton was acquired by the inertial measurement unit(IMU).3DMAX was used to construct a 3-dimensional human skeleton model based on the human skeleton CT.The model was driven by the received sensor data and displayed the instant attitude.The skeletal attitudes and operation information were displayed in real time through the Visual Studio platform,which was displayed on the screen facing the trainee.Thus,a VA combination interactive training system was constructed.Results and Conclusion A set of simulated fracture reduction training system with high accuracy,low cost and VR combination was designed.Compared with the high-cost,precision optical instrument,the root mean square error (RMSE) of the fraction angle calculation was 0.595° in the static state,and was 1.609° in the dynamic state.This system can provide effective information for training operations and provide a new interactive platform for fracture reduction training.