Modeling and Robust Backstepping Sliding Mode Control with Adaptive RBFNN for a Novel Coaxial Eight-rotor UAV

This paper focuses on the robust attitude control of a novel coaxial eight-rotor unmanned aerial vehicles (UAV) which has higher drive capability as well as greater robustness against disturbances than quad-rotor UAV. The dynamical and kinematical model for the coaxial eight-rotor UAV is developed, which has never been proposed before. A robust backstepping sliding mode controller (BSMC) with adaptive radial basis function neural network (RBFNN) is proposed to control the attitude of the eightrotor UAV in the presence of model uncertainties and external disturbances. The combinative method of backstepping control and sliding mode control has improved robustness and simplified design procedure benefiting from the advantages of both controllers. The adaptive RBFNN as the uncertainty observer can effectively estimate the lumped uncertainties without the knowledge of their bounds for the eight-rotor UAV. Additionally, the adaptive learning algorithm, which can learn the parameters of RBFNN online and compensate the approximation error, is derived using Lyapunov stability theorem. And then the uniformly ultimate stability of the eight-rotor system is proved. Finally, simulation results demonstrate the validity of the proposed robust control method adopted in the novel coaxial eight-rotor UAV in the case of model uncertainties and external disturbances. © 2014 Chinese Association of Automation.

Four Wheel Independent Drive Electric Vehicle Lateral Stability Control Strategy

In this paper,a kind of lateral stability control strategy is put forward about the four wheel independent drive electric vehicle.The design of control system adopts hierarchical structure.Unlike the previous control strategy,this paper introduces a method which is the combination of sliding mode control and optimal allocation algorithm.According to the driver’s operation commands(steering angle and speed),the steady state responses of the sideslip angle and yaw rate are obtained.Based on this,the reference model is built.Upper controller adopts the sliding mode control principle to obtain the desired yawing moment demand.Lower controller is designed to satisfy the desired yawing moment demand by optimal allocation of the tire longitudinal forces.Firstly,the optimization goal is built to minimize the actuator cost.Secondly,the weighted least-square method is used to design the tire longitudinal forces optimization distribution strategy under the constraint conditions of actuator and the friction oval.Beyond that,when the optimal allocation algorithm is not applied,a method of axial load ratio distribution is adopted.Finally,Car Sim associated with Simulink simulation experiments are designed under the conditions of different velocities and different pavements.The simulation results show that the control strategy designed in this paper has a good following effect comparing with the reference model and the sideslip angle is controlled within a small rang at the same time.Beyond that,based on the optimal distribution mode,the electromagnetic torque phase of each wheel can follow the trend of the vertical force of the tire,which shows the effectiveness of the optimal distribution algorithm.

The Indirect Shared Steering Control Under Double Loop Structure of Driver and Automation

Due to the critical defects of techniques in fully autonomous vehicles,man-machine cooperative driving is still of great significance in today’s transportation system.Unlike the previous shared control structure,this paper introduces a double loop structure which is applied to indirect shared steering control between driver and automation.In contrast to the tandem indirect shared control,the parallel indirect shared control put the authority allocation system of steering angle into the framework to allocate the corresponding weighting coefficients reasonably and output the final desired steering angle according to the current deviation of vehicle and the accuracy of steering angles.Besides,the active disturbance rejection controller(ADRC)is also added in the frame in order to track the desired steering angle fleetly and accurately as well as restrain the internal and external disturbances effectively which including the steering friction torque,wind speed and ground interference etc.Eventually,we validated the advantages of double loop framework through three sets of double lane change and slalom experiments,respectively.Exactly as we expected,the simulation results show that the double loop structure can effectively reduce the lateral displacement error caused by the driver or the controller,significantly improve the tracking precision and keep great performance in trajectory tracking characteristics when driving errors occur in one of driver and controller.

Textbook Outcome as a measure of surgical quality assessment and prognosis in gastric neuroendocrine carcinoma:A large multicenter sample analysis

Objective:Quality assurance is crucial for oncological surgical treatment assessment.For rare diseases,singlequality indicators are not enough.We aim to develop a comprehensive and reproducible measurement,called the"Textbook Outcome"(TO),to assess the quality of surgical treatment and prognosis of gastric neuroendocrine carcinoma(G-NEC)patients.Methods:Data from patients with primary diagnosed G-NEC included in 24 high-volume Chinese hospitals from October 2005 to September 2018 were analyzed.TO included receiving a curative resection,≥15 lymph nodes examined,no severe postoperative complications,hospital stay≤21 d,and no hospital readmission≤30 d after discharge.Hospital variation in TO was analyzed using a case mix-adjusted funnel plot.Prognostic factors of survival and risk factors for non-Textbook Outcome(non-TO)were analyzed using Cox and logistic models,respectively.Results:TO was achieved in 56.6%of 860 G-NEC patients.TO patients had better overall survival(OS),disease-free survival(DFS),and recurrence-free survival(RFS)than non-TO patients(P<0.05).Moreover,TO patients accounted for 60.3%of patients without recurrence.Multivariate Cox analysis revealed non-TO as an independent risk factor for OS,DFS,and RFS of G-NEC patients(P<0.05).Increasing TO rates were associated with improved OS for G-NEC patients,but not hospital volume.Multivariate logistic regression revealed that nonlower tumors,open surgery,and>200 mL blood loss were independent risk factors for non-TO patients(P<0.05).Conclusions:TO is strongly associated with multicenter surgical quality and prognosis for G-NEC patients.Factors predicting non-TO are identified,which may help guide strategies to optimize G-NEC outcomes.

Multi-centric clinical study of the effect of intervention time on efficacy of gastroparesis external application prescription treatment of gastrointestinal tumor postsurgical gastroparesis

Objective:This intervention has been shown to be clinically efficacious and safe.The aim of this study was to determine the effect of different intervention times on the efficacy of gastroparesis external application prescription versus placebo for the treatment of gastrointestinal tumor postoperative,postsurgical gastroparesis.Methods:A multicenter,randomized,double-blind,placebo controlled phaseⅢclinical trial was designed to demonstrate superiority and conducted at four grade 3A hospitals in Beijing.Patients diagnosed with gastrointestinal tumor postsurgical gastroparesis and local cold syndrome in the abdomen were enrolled and received conventional treatment(nutritional support,gastrointestinal decompression,and prokinetic medication).Treatment and control groups respectively received gastroparesis external application prescription or placebo acupoint application over a treatment course of 14 days or until the primary efficacy endpoint(clinical efficiency)was achieved.Results:A total of 120 patients were enrolled in the treatment and control groups(n Z 60 per group),and 15 patients dropped out of the study because of skin allergies(n Z 7)or poor efficacy(nZ8).The efficacy among patients in Class B of Group A(treatment group)was marginally better than that of Group B(control group)(64.28%vs.55.56%)although the difference between the two groups was not significant.However,the efficacy among patients in Class C of Group A was significantly better than that of Group B(79.49%vs.43.33%).For Group A,the time for patients in the three classes to achieve the efficacy endpoint increased significantly with disease progression(3.00,6.78,and 8.29 days for Class A,B,and C,respectively).Conclusions:Gastroparesis external application prescription can effectively treat gastrointestinal tumor postsurgical gastroparesis and may be more efficacious in progressive disease compared placebo.Patients with gastrointestinal tumor postsurgical gastroparesis should therefore undergo intervention at an earlier stage.

中国胃癌肝转移患者临床诊疗特征及预后分析:全国多中心队列研究(RECORD研究)

Despite surgical improvements and pharmacological advances,management of late-stage gastric cancer patients,especially those with hepatic metastasis remains challenging[1–3].Although nationwide registry data from SEER(Surveillance,Epidemiology,and End Results)[4]and the Nordic database[5]in Western countries have provided epidemiological information for patients with gastric cancer liver metastasis(GCLM),little is known about the detailed clinical characteristics.

Adjuvant chemotherapy may be unnecessary for ypT0-2N0 gastric cancer patients after neoadjuvant chemotherapy and curative gastrectomy

To the Editor:Gastric cancer(GC)is the sixth most common type of cancer and the third most common cause of cancer-related deaths worldwide.[1]Due to the lack of typical clinical symptoms in the early stage of GC,most patients have advanced-stage disease at the time of initial treatment and have a poor prognosis.The rate of radical resection is low.Even after radical resection,recurrence or death occurs in 50%to 90%of patients,and the 5-year overall survival(OS)rate is less than 30%.[2]Therefore,various multimodal strategies,which would presumably reduce the risk of cancer recurrence and improve survival,are being explored to eliminate any residual tumors and micro-metastases.Neoadjuvant chemotherapy(NAC)followed by surgery is recommended as the standard of care for patients with localized resectable GC.

Nomogram for predicting the overall survival of patients after D2/R0 resection and chemoradiotherapy for stage Ⅲ gastric cancer or gastroesophageal junction cancer

Objective:To explore the independent factors associated with the overall survival(OS)after D2/R0 resection and adjuvant chemoradiotherapy(CRT)for stage Ⅲ gastric cancer(GC)and gastroesophageal junction(GEJ)cancer,and establish and validate a nomogram model to predict the OS in this patient population.Methods:A total of 569 stage Ⅲ GC or GEJ cancer patients who underwent D2/R0 resection and adjuvant CRT at our center from January 2013 to May 2018 were retrospectively enrolled in this study.The patients were randomly divided into training and validation cohorts in a 3:1 ratio.In the training cohort,univariate and multivariate analysis were conducted to identify clinical factors associated with OS,and a nomogram model was established on the basis of the independent factors.The concordance index(C-index)and the calibration curve were used to validate the prediction power of the nomogram.Results:Overall,427 and 142 patients were enrolled in the training and validation cohorts,respectively.In the univariate and multivariate analyses,age,Lauren's classification,TNM stage,and administration of adjuvant CRT were independent factors for OS to construct the nomogram.The C-index values were 0.654 and 0.613 in the training and validation cohorts,respectively.The calibration curves were identical to the actual OS.Risk stratification based on the nomogram model showed good risk stratification for OS in both groups.Conclusion:Our study included adjuvant CRT as a predictive factor and established a nomogram model for predicting the OS in patients with stage III GC or GEJ after D2/R0 resection and adjuvant therapy.This nomogram could facilitate more individualized prediction of OS in clinical practice.

Survival of patients with gastric cancer surgically treated at the National Cancer Center of China from 2011 to 2018 according to stage at diagnosis

Objective:The postoperative survival rates of patients with gastric cancer at different stages treated at the National Cancer Center(NCC)of China have not been reported.Therefore,we evaluated the survival of patients with gastric cancer who underwent surgery at the NCC from 2011 to 2018 to provide baseline information for further studies.Methods:We identified 7,301 patients with primary gastric carcinoma who underwent surgery at the NCC be-tween January 2011 and May 2018;among these,5,008 patients were enrolled in this study.Follow up was completed on April 30,2020.We analyzed the 5-year survival according to the stage,sex,age,and other clini-copathological features.Results:Five-year survival rates of patients with pTNM stages ⅠA,ⅠB,ⅡA,ⅡB,ⅢA,ⅢB,ⅢC,and Ⅳ treated at the NCC were 94.9%,91.8%,86.5%,76.1%,61.1%,44.2%,29.7%,and 8.1%,respectively,which were similar to those reported in Japan during the same period.Five-year survival rates of patients with ypTNM stages I,II,III,and IV were 93.1%,63.2%,27.2%,and 0.0%,respectively.In multivariable analysis,age,signet ring cell carcinoma,adjuvant chemotherapy,and degree of differentiation were revealed as important prognostic factors.Conclusion:The survival rates of patients with gastric cancer treated at the NCC have been significantly improved,reaching the levels of Japan in the same period.

Backstepping sliding mode tracking control of quad-rotor under input saturation

Purpose–The quad-rotor is an under-actuation,strong coupled nonlinear system with parameters uncertainty,unmodeled disturbance and drive capability boundedness.The purpose of the paper is to design a flight control system to regulate the aircraft track the desired trajectory and keep the attitude angles stable on account of these issues.Design/methodology/approach–Considering the dynamics of a quad-rotor,the closed-loop flight control system is divided into two nested loops:the translational outer-loop and the attitude inner-loop.In the outer-loop,the translational controller,which exports the desired attitude angles to the inner-loop,is designed based on bounded control technique.In consideration of the influence of uncertain rotational inertia and external disturbance,the backstepping sliding mode approach with adaptive gains is used in the inner-loop.The switching control strategy based on the sign functions of sliding surface is introduced into the design procedure with respect to the input saturation.Findings–The validity of the proposed flight control system was verified through numerical simulation and prototype flight experiment in this paper.Furthermore,with relation to the flying,the motor speed is kept in the predetermined scope.Originality/value–This article introduces a new flight control system designed for a quad-rotor.