The lower limb rigid rehabilitation exoskeleton is research emphasis in lower limb disability assistance and rehabilitation. Modular joints integration in exoskeleton provides high-efficient ...human-robot interaction. However, it is difficult to achieve miniaturization of structure design. Meanwhile, the lack of constraint design in control makes it difficult to meet the requirements of interaction. A novel SEA modular joint is proposed and the related control problem under constraints are established in this paper. Benefited from interval switching strategy, the proposed SEA modular joint has variable stiffness characteristics while the control complexity introduced by nonlinearity is reduced. On the control of SEA modular joint, the framework of model predictive control (MPC) is applied. The iterative linearization is presented to resolve the nonlinearity of system and the modified cost function in MPC is presented to achieve the prescribed degree of stability. The trajectory tracking and disturbance experiments are conducted. The results show that the proposed method can realize the tracking of reference trajectory while satisfying control constraints. The controller can reject disturbance effectively and modified cost function enhances MPC performance significantly.
In this paper, an adaptive weighted control method for Hammerstein-Wiener nonlinear systems has been derived by considering the tracking of the references while simultaneously minimizing the control ...effort. Based on the parameterization model of Hammerstein-Wiener systems, parameter adaptation is implemented throughout the use of internal variable estimations. Based on these estimates, the control law is designed by analyzing a new criterion function which takes the whole nonlinear systems into account and penalizes the excessive control action according to the nonlinear gains. By simplifying the above complex control law, we obtain a simple adaptive weighted control algorithm, which reduces overshoot and oscillation effectively. The closed-loop stability and output tracking properties are analyzed to demonstrate the proposed novel concepts. Illustrative simulation results are presented to verify the effectiveness of the proposed algorithms.
This paper designs a compliance controller by imitating human walking characteristics, balance recovery strategy, and combining anomaly detection algorithm for lower limb exoskeleton. Our final goal ...is to run it on the lower limb exoskeleton. We first analyze the characteristics human balance control and introduce an anomaly detection algorithm based on One-Class Support Vector Machine (OCSVM). Then, according to the abnormal index, the controller is designed for each joint with the law of human joint activity. Finally, the results of human-exoskeleton experiment showed that the exoskeleton can balance recovery when the Center of Mass (CoM) of the human-exoskeleton system is over the range of balance.
Objective： To determine whether maternal β-human chorionic gonadotropin（β-hCG） level in second-trimester may be associated with subsequent development of pregnancy-induced hypertension（PIH）. Methods： ...Seven hundred and sixty-two women in mid-trimester were to have maternal urine β-hCG standardized concentrations and maternal serum ~-hCG measurements. Their case histories were recorded and reviewed from mid-trimester to delivery. The relation was observed between maternal urine, serum markers and subsequent development of PIH. Results： Among 762 women, 504 cases were normal pregnancies, 42 cases had PIH, 94 cases had premature rupture of membrane （PROM）, 69 cases had preterm delivery （PD）, 53 other cases were excluded by various reasons. The levels of maternal urine, serum β-hCG in PIH were （61.75±9.78） IU/L and （304.56 ±54.17） ng/mg respectively, which were higher significantly than normal pregnancy group （20.65 ±7.61 IU/L and 146.34±47.81 ng/mg, P〈0.05）. When maternal serum, urine β-hCG levels ≥2 MOM （multiple of mean） , the incidences of developing PIH were increased significantly as compared with those of β-hCG 〈2 MOM women. The incidence of PIH increased from 5.1% in pregnancies with urine β-hCG ≥2 MOM to 11.7% in cases with urine β-hCG ≥4 MOM. Conclusion： The elevation of maternal mid-trimester urine, serum β-hCG levels is not only an early signal for dysfunction of placenta but also a dangerous signal for development of PIH. Second-trimester maternal urine β-hCG measurement proves to be superior to serum marker in clinical prediction.
Machine vision faces bottlenecks in computing power consumption and large amounts of data. Although opto-electronic hybrid neural networks can provide assistance, they usually have complex structures ...and are highly dependent on a coherent light source; therefore, they are not suitable for natural lighting environment applications. In this paper, we propose a novel lensless opto-electronic neural network architecture for machine vision applications. The architecture optimizes a passive optical mask by means of a task-oriented neural network design, performs the optical convolution calculation operation using the lensless architecture, and reduces the device size and amount of calculation required. We demonstrate the performance of handwritten digit classification tasks with a multiple-kernel mask in which accuracies of as much as 97.21% were achieved. Furthermore, we optimize a large-kernel mask to perform optical encryption for privacy-protecting face recognition, thereby obtaining the same recognition accuracy performance as no-encryption methods. Compared with the random MLS pattern, the recognition accuracy is improved by more than 6%.
We tested the hypothesis that 1,25‐dihydroxyvitamin D31α,25(OH)2D3 has antiaging effects via upregulating nuclear factor (erythroid‐derived 2)‐like 2 (Nrf2), reducing reactive oxygen species (ROS), ...decreasing DNA damage, reducing p16/Rb and p53/p21 signaling, increasing cell proliferation, and reducing cellular senescence and the senescence‐associated secretory phenotype (SASP). We demonstrated that 1,25(OH)2D3‐deficient 1α(OH)ase−/− mice survived on average for only 3 months. Increased tissue oxidative stress and DNA damage, downregulated Bmi1 and upregulated p16, p53 and p21 expression levels, reduced cell proliferation, and induced cell senescence and the senescence‐associated secretory phenotype (SASP) were observed. Supplementation of 1α(OH)ase−/− mice with dietary calcium and phosphate, which normalized serum calcium and phosphorus, prolonged their average lifespan to more than 8 months with reduced oxidative stress and cellular senescence and SASP. However, supplementation with exogenous 1,25(OH)2D3 or with combined calcium/phosphate and the antioxidant N‐acetyl‐l‐cysteine prolonged their average lifespan to more than 16 months and nearly 14 months, respectively, largely rescuing the aging phenotypes. We demonstrated that 1,25(OH)2D3exerted an antioxidant role by transcriptional regulation of Nrf2 via the vitamin D receptor (VDR). Homozygous ablation of p16 or heterozygous ablation of p53 prolonged the average lifespan of 1α(OH)ase−/− mice on the normal diet from 3 to 6 months by enhancing cell proliferative ability and reducing cell senescence or apoptosis. This study suggests that 1,25(OH)2D3 plays a role in delaying aging by upregulating Nrf2, inhibiting oxidative stress and DNA damage，inactivating p53‐p21 and p16‐Rb signaling pathways, and inhibiting cell senescence and SASP.
1,25(OH)2D3 deficiency results in increasing oxidative stress through inhibiting transcription of Nrf2 and enhancing DNA damage; in addition, activation of p16/Rb and p53/p21 signaling occurs. These events then lead to inhibition of cellular proliferation and induction of cellular senescence and SASP, and thus acceleration of aging. These processes may be rescued to different degrees and aging postponed by supplementation of exogenous 1,25(OH)2D3, calcium/phosphate alone or combined calcium/phosphate and antioxidant NAC, or knockdown of p53 or knockout of p16.
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