Development of Admittance Control Method with Parameter Self-optimization for Hydraulic Series Elastic Actuator

Haoran Zhong,Xinyu Li,Liang Gao,Haozhen Dong 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.7

Series elastic actuators (SEAs) have emerged as promising devices to enhance the safety of human-robot interactions in the manufacturing industry. However, the control of a hydraulic SEA under disturbance remains an unexplored issue. To address this problem, an admittance control method with parameter self-optimization is developed in this study. The hydraulic SEA and its dynamic model are first developed, and then, an admittance controller that combines a passive disturbance observer (DOB) and a feedback compensator is developed based on load movement dynamics. The control law of the framework is made independent of the hydraulic dynamics by considering the uncertainty and tracking error as disturbances. This simplifies the controller computation, enhances system robustness, and facilitates practical application. Next, the control performance is further improved by optimizing the control parameters using an improved crowding-based dynamic population size differential evolution (crowdingbased dynNP-DE) algorithm. Benchmark and optimization experiments are performed to verify the superiority of the modified algorithm and obtain the control parameters. Finally, the optimized parameters are applied to practical experiments to validate the improved performance of the proposed admittance control scheme. The results show that the proposed method effectively reduces the SEA stiffness tracking error, with respect to the external contact force.

Oxygen tank for synergistic hypoxia relief to enhance mitochondria-targeted photodynamic therapy

Xianghui Li,Haoran Wang,Zhiyan Li,Dandan Li,Xiaofeng Lu,Shichao Ai,Yuxiang Dong,Song Liu,Jinhui Wu,Wenxian Guan 한국생체재료학회 2022 생체재료학회지 Vol.26 No.4

Background: Mitochondria play an essential role in cellular redox homeostasis maintenance and meanwhile serve as an important target for organelle targeted therapy. Photodynamic therapy (PDT) is a promising strategy for organelle targeted therapy with noninvasive nature and highly spatiotemporal selectivity. However, the efficacy of PDT is not fully achieved due to tumor hypoxia. Moreover, aerobic respiration constantly consumes oxygen and leads to a lower oxygen concentration in mitochondria, which continuously limited the therapeutic effects of PDT. The lack of organelle specific oxygen delivery method remains a main challenge. Methods: Herein, an Oxygen Tank is developed to achieve the organelle targeted synergistic hypoxia reversal strategy, which not only act as an oxygen storage tank to open sources and reduce expenditure, but also coated with red blood cell membrane like the tank with stealth coating. Within the oxygen tank, a mitochondrion targeted photosensitizer (IR780) and a mitochondria respiration inhibitor (atovaquone, ATO) are co-loaded in the RBC membrane (RBCm) coated perfluorocarbon (PFC) liposome core. Results: Inside these bio-mimic nanoparticles, ATO effectively inhibits mitochondrial respiration and economized endogenous oxygen consumption, while PFC supplied high-capacity exogenous oxygen. These Oxygen modulators reverse the hypoxia status in vitro and in vivo, and exhibited a superior anti-tumor activity by mitochondria targeted PDT via IR780. Ultimately, the anti-tumor effects towards gastric cancer and colon cancer are elicited in vivo. Conclusions: This oxygen tank both increases exogeneous oxygen supply and decreases endogenous oxygen consumption, may offer a novel solution for organelle targeted therapies.

DeepPTP: A Deep Pedestrian Trajectory Prediction Model for Traffic Intersection

( Zhiqiang Lv ),( Jianbo Li ),( Chuanhao Dong ),( Yue Wang ),( Haoran Li ),( Zhihao Xu ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.7

Compared with vehicle trajectories, pedestrian trajectories have stronger degrees of freedom and complexity, which poses a higher challenge to trajectory prediction tasks. This paper designs a mode to divide the trajectory of pedestrians at a traffic intersection, which converts the trajectory regression problem into a trajectory classification problem. This paper builds a deep model for pedestrian trajectory prediction at intersections for the task of pedestrian short-term trajectory prediction. The model calculates the spatial correlation and temporal dependence of the trajectory. More importantly, it captures the interactive features among pedestrians through the Attention mechanism. In order to improve the training speed, the model is composed of pure convolutional networks. This design overcomes the single-step calculation mode of the traditional recurrent neural network. The experiment uses Vulnerable Road Users trajectory dataset for related modeling and evaluation work. Compared with the existing models of pedestrian trajectory prediction, the model proposed in this paper has advantages in terms of evaluation indicators, training speed and the number of model parameters.

SiC IGBT degradation mechanism investigation under HV‑H3TRB tests

Ziming Wu,Zongbei Dai,Jian Zhou,Huafeng Dong,Wencan Wang,Feiwan Xie,Haoran Wang,Jiahui Yan,Xiyu Chen,Shaohua Yang,Fugen Wu 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.2

The high voltage-high humidity-high temperature reverse bias (HV-H3TRB) test was utilized to evaluate the reliability of silicon carbide insulated gate bipolar transistors (SiC IGBTs). Moisture invasion often induces termination/passivation and metal corrosion. Therefore, the HV-H3TRB test is generally used to assess termination / passivation robustness. However, under the HV-H3TRB test conditions, gate quality degradation may occur. In this study, the dominant degradation mechanism of SiC IGBTs was investigated. The changes of the most sensitive static characteristics (e.g., threshold voltage, breakdown voltage, and leakage current) were recorded. The threshold voltage decreased and leakage current increased substantially after > 1000 h of HV-H3TRB tests under 85 ℃/85% RH climate conditions. Capacitance-voltage (C-V) curve measurements indicated that the mobile ions at the SiC/SiO2 interface or in the gate oxide likely caused the threshold-voltage instability in the SiC IGBTs after the HV-H3TRB tests. This instability can be recovered by applying a negative gate bias. Subsequent failure analysis confirmed no corrosion of metals or termination/passivation in the device, which indicates the robustness of the passivation (consisting of phosphor-silicate glass and Si3N4). Therefore, the gate quality appears to be a significant reliability risk for SiC IGBTs under high humidity, high temperature, and high voltage conditions.

Updated Bayesian Network Meta-Analysis of Adjuvant Targeted Treatment Regimens for Early Human Epidermal Growth Factor Receptor-2 Positive Breast Cancer

Xinyan Li,Litong Yao,Mozhi Wang,Mengshen Wang,Xiang Li,Xueting Yu,Jingyi Guo,Haoran Dong,Xiangyu Sun,Yingying Xu 한국유방암학회 2020 Journal of breast cancer Vol.23 No.4

Purpose: Combining targeted agents with adjuvant chemotherapy prolongs survival in human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients, but also increases the risk of adverse effects. The updated results of 3 randomized controlled trials (RCTs) were reported in 2019. Given the lack of adequate head-to-head pairwise assessment for anti-HER2 agents, network meta-analysis facilitates obtaining more precise inference for evidence-based therapy. Methods: RCTs comparing at least 2 anti-HER2 regimens in an adjuvant setting for HER2- positive early-stage breast cancer (EBC) were included. Hazard ratios for overall survival (OS) and disease free survival (DFS), with respective 95% confidence intervals were pooled for assessment of efficacy. A Bayesian statistical model was used, and odds ratios (ORs) for adverse events (AEs) were used to pool effect sizes. Results: We demonstrated that 1-year trastuzumab plus chemotherapy had increased efficacy compared to shorter or longer treatment duration. The OR of cardiac events gradually increased from 6 months to 1 and 2-year trastuzumab arms, relative to chemotherapy only. Compared to trastuzumab plus chemotherapy, dual HER2-targeting therapies increased DFS, especially for hormone receptor negative patients. Dual anti-HER2 blockade regimens revealed an increased probability of gastrointestinal reactions. As a second agent, pertuzumab showed significantly higher DFS and OS. Conclusion: We conclude that 1-year adjuvant trastuzumab should remain as the standard treatment for HER2-positive EBC patients, as it has greater efficacy and a manageable proportion of AEs. Clinical efficacy can be increased for hormone receptor-negative tumors by including a second HER2-targeted agent to the treatment regimen. For hormone receptor-positive cases with basal disease, it is acceptable to reduce the risk of cardiotoxicity by shortening the duration of trastuzumab.