A Stability Analysis for the Acceleration-based Robust Position Control of Robot Manipulators via Disturbance Observer

This paper proposes a new nonlinear stability analysis for the acceleration-based robust position control of robot manipulators by using Disturbance Observer (DOb). It is shown that if the nominal inertia matrix is properly tuned in the design of DOb, then the position error asymptotically goes to zero in regulation control and is uniformly ultimately bounded in trajectory tracking control. As the bandwidth of DOb and the nominal inertia matrix are increased, the bound of error shrinks, i.e., the robust stability and performance of the position control system are improved. However, neither the bandwidth of DOb nor the nominal inertia matrix can be freely increased due to practical design constraints, e.g., the robust position controller becomes more noise sensitive when they are increased. The proposed stability analysis provides insights regarding the dynamic behavior of DOb-based robust motion control systems. It is theoretically and experimentally proved that non-diagonal elements of the nominal inertia matrix are useful to improve the stability and adjust the trade-off between the robustness and noise sensitivity. The validity of the proposal is verified by simulation and experimental results.Comment: 9 pages, 9 figures, Journa

A Stability Analysis for the Acceleration-based Robust Position Control of Robot Manipulators via Disturbance Observer

This paper proposes a new nonlinear stability analysis for the acceleration-based robust position control of robot manipulators by using Disturbance Observer (DOb). It is shown that if the nominal inertia matrix is properly tuned in the design of DOb, then the position error asymptotically goes to zero in regulation control and is uniformly ultimately bounded in trajectory tracking control. As the bandwidth of DOb and the nominal inertia matrix are increased, the bound of error shrinks, i.e., the robust stability and performance of the position control system are improved. However, neither the bandwidth of DOb nor the nominal inertia matrix can be freely increased due to practical design constraints, e.g., the robust position controller becomes more noise sensitive when they are increased. The proposed stability analysis provides insights regarding the dynamic behavior of DOb-based robust motion control systems. It is theoretically and experimentally proved that non-diagonal elements of the nominal inertia matrix are useful to improve the stability and adjust the trade-off between the robustness and noise sensitivity. The validity of the proposal is verified by simulation and experimental results

CXCL12 is expressed by skeletal muscle cells in tongue oral squamous cell carcinoma

Abstract Background The CXCL12/CXCR4 axis plays a pivotal role in the progression of various malignancies, including oral squamous cell carcinoma (OSCC). In this study, we aimed to clarify the biological and clinical significance of CXCL12 in the tumor microenvironment of OSCCs. Methods Publicly available single‐cell RNA‐sequencing (RNA‐seq) datasets were used to analyze CXCL12 expression in head and neck squamous cell carcinomas (HNSCC). Immunohistochemical analysis of CXCL12, α‐smooth muscle antigen (α‐SMA), fibroblast activation protein (FAP) and CD8 was performed in a series of 47 surgically resected primary tongue OSCCs. Human skeletal muscle cells were co‐cultured with or without OSCC cells, after which CXCL12 expression was analyzed using quantitative reverse‐transcription PCR. Results Analysis of the RNA‐seq data suggested CXCL12 is abundantly expressed in stromal cells within HNSCC tissue. Immunohistochemical analysis showed that in grade 1 primary OSCCs, CXCL12 is expressed in both tumor cells and muscle cells. By contrast, grade 3 tumors were characterized by disruption of muscle structure and reduced CXCL12 expression. Quantitative analysis of CXCL12‐positive areas within tumors revealed that reduced CXCL12 expression correlated with poorer overall survival. Levels of CXCL12 expression tended to inversely correlate α‐SMA expression and positively correlate with infiltration by CD8+ lymphocytes, though these relations did not reach statistical significance. CXCL12 was significantly upregulated in muscle cells co‐cultured with OSCC cells. Conclusion Our results suggest that tongue OSCC cells activate CXCL12 expression in muscle cells, which may contribute to tumor progression. However, CXCL12 is reduced in advanced OSCCs due to muscle tissue destruction

Discovery of Gemilukast (ONO-6950), a Dual CysLT₁ and CysLT₂ Antagonist As a Therapeutic Agent for Asthma

An orally active dual CysLT₁ and CysLT₂ antagonist possessing a distinctive structure which consists of triple bond and dicarboxylic acid moieties is described. Gemilukast (ONO-6950) was generated via isomerization of the core indole and the incorporation of a triple bond into a lead compound. Gemilukast exhibited antagonist activities with IC₅₀ values of 1.7 and 25 nM against human CysLT₁ and human CysLT₂, respectively, and potent efficacy at an oral dose of 0.1 mg/kg given 24 h before LTD₄ challenge in a CysLT₁-dependent guinea pig asthmatic model. In addition, gemilukast dose-dependently reduced LTC₄-induced bronchoconstriction in both CysLT₁- and CysLT₂-dependent guinea pig asthmatic models, and it reduced antigen-induced constriction of isolated human bronchi. Gemilukast is currently being evaluated in phase II trials for the treatment of asthma

Discovery of Gemilukast (ONO-6950), a Dual CysLT₁ and CysLT₂ Antagonist As a Therapeutic Agent for Asthma

An orally active dual CysLT₁ and CysLT₂ antagonist possessing a distinctive structure which consists of triple bond and dicarboxylic acid moieties is described. Gemilukast (ONO-6950) was generated via isomerization of the core indole and the incorporation of a triple bond into a lead compound. Gemilukast exhibited antagonist activities with IC₅₀ values of 1.7 and 25 nM against human CysLT₁ and human CysLT₂, respectively, and potent efficacy at an oral dose of 0.1 mg/kg given 24 h before LTD₄ challenge in a CysLT₁-dependent guinea pig asthmatic model. In addition, gemilukast dose-dependently reduced LTC₄-induced bronchoconstriction in both CysLT₁- and CysLT₂-dependent guinea pig asthmatic models, and it reduced antigen-induced constriction of isolated human bronchi. Gemilukast is currently being evaluated in phase II trials for the treatment of asthma