目的探讨线上工作坊模式对内科专业住院医师规范化培训(简称住培)指导医师临床操作技能直接观察评估(direct observation of procedural skills,DOPS)师资培训的应用效果。方法选取2022年11月参加广东省内科专业住培普通师资培训班的45...目的探讨线上工作坊模式对内科专业住院医师规范化培训(简称住培)指导医师临床操作技能直接观察评估(direct observation of procedural skills,DOPS)师资培训的应用效果。方法选取2022年11月参加广东省内科专业住培普通师资培训班的45名指导医师为研究对象,采用线上分组讨论与教学视频评价反馈相结合的线上工作坊模式进行DOPS师资培训,采用问卷自评的方式评价指导医师对DOPS的掌握程度,并通过问卷调查了解培训前后指导医师对线上DOPS的培训需求与满意度。结果培训前仅17.8%的指导医师使用过DOPS量表;指导医师在培训后对DOPS的掌握程度明显高于培训前[(3.71±0.69)分比(2.29±0.87)分,P<0.01];且95.6%及以上的指导医师表示能够理解“DOPS评分项目的均质化制定方法”和“形成性反馈技巧”;100.0%的指导医师表示在今后住培教学中愿意尝试使用DOPS。课程的整体满意度评分为(8.40±1.70)分。结论线上工作坊模式对内科专业住培指导医师DOPS师资培训的短期效果满意,可进一步在住培形成性评价师资培训中推广应用。展开更多
This paper investigates interception missiles’trajectory tracking guidance problem under wind field and external disturbances in the boost phase.Indeed,the velocity control in such trajectory tracking guidance system...This paper investigates interception missiles’trajectory tracking guidance problem under wind field and external disturbances in the boost phase.Indeed,the velocity control in such trajectory tracking guidance systems of missiles is challenging.As our contribution,the velocity control channel is designed to deal with the intractable velocity problem and improve tracking accuracy.The global prescribed performance function,which guarantees the tracking error within the set range and the global convergence of the tracking guidance system,is first proposed based on the traditional PPF.Then,a tracking guidance strategy is derived using the integral sliding mode control techniques to make the sliding manifold and tracking errors converge to zero and avoid singularities.Meanwhile,an improved switching control law is introduced into the designed tracking guidance algorithm to deal with the chattering problem.A back propagation neural network(BPNN)extended state observer(BPNNESO)is employed in the inner loop to identify disturbances.The obtained results indicate that the proposed tracking guidance approach achieves the trajectory tracking guidance objective without and with disturbances and outperforms the existing tracking guidance schemes with the lowest tracking errors,convergence times,and overshoots.展开更多
目的探讨基于改良Peyton四步教学法的模拟教学联合操作技能直接观察(direct observation of procedural skills,DOPS)评估方法在西藏临床技能培训中的应用效果。方法选取西藏边坝县人民医院2021年5月—2022年5月参加临床技能培训的51名...目的探讨基于改良Peyton四步教学法的模拟教学联合操作技能直接观察(direct observation of procedural skills,DOPS)评估方法在西藏临床技能培训中的应用效果。方法选取西藏边坝县人民医院2021年5月—2022年5月参加临床技能培训的51名医护人员为研究对象,随机分为试验组与对照组。试验组采用结合改良Peyton四步教学法进行成人男性导尿术教学,并在培训开始前、培训中期及培训结束后,由带教教师采用DOPS评估方法对学员进行测评。对照组采用传统临床技能培训方法进行教学。在培训结束后发放满意度调查问卷,以了解学员对该教学模式的满意度。结果试验组技能考核平均成绩(90.12±5.50)分,对照组技能考核平均成绩(79.36±6.95)分,两组间成绩比较,其差异具有统计学意义(P<0.001);DOPS评估量表显示,试验组学员在培训结束后临床操作各项能力均较前有显著提高,其差异均具有统计学意义(P<0.05);课后满意度调查结果显示,在赞同“增强相关基础知识”等6个方面,试验组与对照组比较,其差异均具有统计学意义(P<0.001)。结论基于改良Peyton四步教学法的模拟教学联合DOPS评估方法的教学模式可提高西藏藏区医护人员的临床技能操作水平,适合在藏区医护人员临床技能培训中推广。展开更多
目的:评估操作技能直接观察评估(direct observation of procedural skills,DOPS)在血管超声技能教学中的效果。方法:选取浙江大学医学院附属第一医院超声医学2019级-2021级住培医师40名为对象。结果:三年级DOPS试验组成绩高于三年级传...目的:评估操作技能直接观察评估(direct observation of procedural skills,DOPS)在血管超声技能教学中的效果。方法:选取浙江大学医学院附属第一医院超声医学2019级-2021级住培医师40名为对象。结果:三年级DOPS试验组成绩高于三年级传统对照组(P=0.048),三年级传统对照组成绩与二年级DOPS试验组差异没有统计意义(P=0.512)。结论:应用DOPS可显著提升住培医师血管超声的技能操作能力和学习效率,值得进一步研究并在住院医师规范化培训中应用。展开更多
This paper proposes a new global fixed-time sliding mode control strategy for the trajectory tracking control of uncertain robotic manipulators.First,a fixed-time disturbance observer(FTDO) is designed to deal with th...This paper proposes a new global fixed-time sliding mode control strategy for the trajectory tracking control of uncertain robotic manipulators.First,a fixed-time disturbance observer(FTDO) is designed to deal with the adverse effects of model uncertainties and external disturbances in the manipulator systems.Then an adaptive scheme is used and the adaptive FTDO(AFTDO) is developed,so that the priori knowledge of the lumped disturbance is not required.Further,a new non-singular fast terminal sliding mode(NFTSM) surface is designed by using an arctan function,which helps to overcome the singularity problem and enhance the robustness of the system.Based on the estimation of the lumped disturbance by the AFTDO,a fixed-time non-singular fast terminal sliding mode controller(FTNFTSMC)is developed to guarantee the trajectory tracking errors converge to zero within a fixed time.The settling time is independent of the initial state of the system.In addition,the stability of the AFTDO and FTNFTSMC is strictly proved by using Lyapunov method.Finally,the fixed-time NFESM(FTNFTSM) algorithm is validated on a 2-link manipulator and comparisons with other existing sliding mode controllers(SMCs) are performed.The comparative results confirm that the FTNFTSMC has superior control performance.展开更多
In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated...In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated estimation guidance and control nonlinear model with limited actuator deflection angle is established considering the seeker's FOV constraint.The boundary time-varying integral barrier Lyapunov function(IBLF)is employed in backstepping design to constrain the body line-of-sight(BLOS)in IEGC system to fit a circular FOV.Then,the nonlinear adaptive controller is designed to estimate the changing aerodynamic parameters.The generalized extended state observer(GESO)is designed to estimate the acceleration of the maneuvering targets and the unmatched time-varying disturbances for improving tracking accuracy.Furthermore,the command filters are used to solve the"differential expansion"problem during the backstepping design.The Lyapunov theory is used to prove the stability of the overall closed-loop IEGC system.Finally,the simulation results validate the integrated system's effectiveness,achieving high accuracy strikes against maneuvering targets.展开更多
With the increasing precision of guidance,the impact of autopilot dynamic characteristics and target maneuvering abilities on precision guidance is becoming more and more significant.In order to reduce or even elimina...With the increasing precision of guidance,the impact of autopilot dynamic characteristics and target maneuvering abilities on precision guidance is becoming more and more significant.In order to reduce or even eliminate the autopilot dynamic operation and the target maneuvering influence,this paper suggests a guidance system model involving a novel integral sliding mode guidance law(ISMGL).The method utilizes the dynamic characteristics and the impact angle,combined with a sliding mode surface scheme that includes the desired line-ofsight angle,line-of-sight angular rate,and second-order differential of the angular line-of-sight.At the same time,the evaluation scenario considere the target maneuvering in the system as the external disturbance,and the non-homogeneous disturbance observer estimate the target maneuvering as a compensation of the guidance command.The proposed system’s stability is proven based on the Lyapunov stability criterion.The simulations reveale that ISMGL effectively intercepted large maneuvering targets and present a smaller miss-distance compared with traditional linear sliding mode guidance laws and trajectory shaping guidance laws.Furthermore,ISMGL has a more accurate impact angle and fast convergence speed.展开更多
This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theor...This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theory,a disturbance observer with integral sliding mode and adaptive techniques is proposed to mitigate total disturbance effects,irrespective of initial conditions.By introducing an error integral signal,the dynamics of the SGGP are transformed into two separate second-order fully actuated systems.Subsequently,employing the high-order fully actuated approach and a parametric approach,the nonlinear dynamics of the SGGP are recast into a constant linear closed-loop system,ensuring that the projectile's attitude asymptotically tracks the given goal with the desired eigenstructure.Under the proposed composite control framework,the ultimately uniformly bounded stability of the closed-loop system is rigorously demonstrated via the Lyapunov method.Validation of the effectiveness of the proposed attitude autopilot design is provided through extensive numerical simulations.展开更多
In this paper,a bandwidth-adjustable extended state observer(ABESO)is proposed for the systems with measurement noise.It is known that increasing the bandwidth of the observer improves the tracking speed but tolerates...In this paper,a bandwidth-adjustable extended state observer(ABESO)is proposed for the systems with measurement noise.It is known that increasing the bandwidth of the observer improves the tracking speed but tolerates noise,which conflicts with observation accuracy.Therefore,we introduce a bandwidth scaling factor such that ABESO is formulated to a 2-degree-of-freedom system.The observer gain is determined and the bandwidth scaling factor adjusts the bandwidth according to the tracking error.When the tracking error decreases,the bandwidth decreases to suppress the noise,otherwise the bandwidth does not change.It is proven that the error dynamics are bounded and converge in finite time.The relationship between the upper bound of the estimation error and the scaling factor is given.When the scaling factor is less than 1,the ABESO has higher estimation accuracy than the linear extended state observer(LESO).Simulations of an uncertain nonlinear system with compound disturbances show that the proposed ABESO can successfully estimate the total disturbance in noisy environments.The mean error of total disturbance of ABESO is 15.28% lower than that of LESO.展开更多
Hydraulic manipulators are usually applied in heavy-load and harsh operation tasks.However,when faced with a complex operation,the traditional proportional-integral-derivative(PID)control may not meet requirements for...Hydraulic manipulators are usually applied in heavy-load and harsh operation tasks.However,when faced with a complex operation,the traditional proportional-integral-derivative(PID)control may not meet requirements for high control performance.Model-based full-state-feedback control is an effective alternative,but the states of a hydraulic manipulator are not always available and reliable in practical applications,particularly the joint angular velocity measurement.Considering that it is not suitable to obtain the velocity signal directly from differentiating of position measurement,the low-pass filtering is commonly used,but it will definitely restrict the closed-loop bandwidth of the whole system.To avoid this problem and realize better control performance,this paper proposes a novel observerbased adaptive robust controller(obARC)for a multi-joint hydraulic manipulator subjected to both parametric uncertainties and the lack of accurate velocity measurement.Specifically,a nonlinear adaptive observer is first designed to handle the lack of velocity measurement with the consideration of parametric uncertainties.Then,the adaptive robust control is developed to compensate for the dynamic uncertainties,and the close-loop system robust stability is theoretically proved under the observation and control errors.Finally,comparative experiments are carried out to show that the designed controller can achieve a performance improvement over the traditional methods,specifically yielding better control accuracy owing to the closed-loop bandwidth breakthrough,which is limited by low-pass filtering in fullstate-feedback control.展开更多
Permanent magnet synchronous motor(PMSM)speed control systems with conventional linear active disturbance rejection control(CLADRC)strategy encounter issues regarding the coupling between dynamic response and disturba...Permanent magnet synchronous motor(PMSM)speed control systems with conventional linear active disturbance rejection control(CLADRC)strategy encounter issues regarding the coupling between dynamic response and disturbance suppression and have poor performance in suppressing complex nonlinear disturbances.In order to address these issues,this paper proposes an improved two-degree-of-freedom LADRC(TDOF-LADRC)strategy,which can enhance the disturbance rejection performance of the system while decoupling entirely the system's dynamic and anti-disturbance performance to boost the system robustness and simplify controller parameter tuning.PMSM models that consider total disturbances are developed to design the TDOF-LADRC speed controller accurately.Moreover,to evaluate the control performance of the TDOF-LADRC strategy,its stability is proven,and the influence of each controller parameter on the system control performance is analyzed.Based on it,a comparison is made between the disturbance observation ability and anti-disturbance performance of TDOF-LADRC and CLADRC to prove the superiority of TDOF-LADRC in rejecting disturbances.Finally,experiments are performed on a 750 W PMSM experimental platform,and the results demonstrate that the proposed TDOF-LADRC exhibits the properties of two degrees of freedom and improves the disturbance rejection performance of the PMSM system.展开更多
Dear Editor,In this letter,an output tracking control problem of uncertain cyber-physical systems(CPSs)is considered in the perspective of high-order fully actuated(HOFA)system theory,where a lumped disturbance is use...Dear Editor,In this letter,an output tracking control problem of uncertain cyber-physical systems(CPSs)is considered in the perspective of high-order fully actuated(HOFA)system theory,where a lumped disturbance is used to denote the total uncertainties containing parameters perturbations and external disturbances.展开更多
The Rotary Inverted Pendulum(RIP)is a widely used underactuated mechanical system in various applications such as bipedal robots and skyscraper stabilization where attitude control presents a significant challenge.Des...The Rotary Inverted Pendulum(RIP)is a widely used underactuated mechanical system in various applications such as bipedal robots and skyscraper stabilization where attitude control presents a significant challenge.Despite the implementation of various control strategies to maintain equilibrium,optimally tuning control gains to effectively mitigate uncertain nonlinearities in system dynamics remains elusive.Existing methods frequently rely on extensive experimental data or the designer’s expertise,presenting a notable drawback.This paper proposes a novel tracking control approach for RIP,utilizing a Linear Quadratic Regulator(LQR)in combination with a reduced-order observer.Initially,the RIP system is mathematically modeled using the Newton-Euler-Lagrange method.Subsequently,a composite controller is devised that integrates an LQR for generating nominal control signals and a reduced-order observer for reconstructing unmeasured states.This approach enhances the controller’s robustness by eliminating differential terms from the observer,thereby attenuating unknown disturbances.Thorough numerical simulations and experimental evaluations demonstrate the system’s capability to maintain balance below50Hz and achieve precise tracking below1.4 rad,validating the effectiveness of the proposed control scheme.展开更多
BACKGROUND Determination of platybasia and basilar kyphosis are significant parts of routine cranial magnetic resonance(MR)interpretations.These situations may explain a patient’s symptoms or may be associated with o...BACKGROUND Determination of platybasia and basilar kyphosis are significant parts of routine cranial magnetic resonance(MR)interpretations.These situations may explain a patient’s symptoms or may be associated with other anomalies.AIM To indicate the interobserver and intraobserver reliability of the skull base angles(SBA)(Koenigsberg standard)and modified SBA(mSBA)measurement techniques.METHODS In total,391 patients who had undergone cranial MR imaging were re-assessed regarding the SBA measurements.The SBA and mSBA techniques were used on MR images.Two reviewers independently measured the same angles twice within a 15-day interval,using different monitors.Intraclass correlation coefficient(ICC)was calculated to reveal the intraobserver and interobserver agreements.RESULTS There was an excellent agreement between reviewers regarding both angle measurements(ICC was 0.998 for SBA and mSBA).Excellent agreement levels were also observed for intraobserver measurements.ICC was 0.998 for SBA and 0.999 for mSBA for reviewer 1.ICC was 0.997 for SBA and 0.999 for mSBA according to the measurement results of reviewer 2.Higher SBA and mSBA values were observed for females compared to males.There was no correlation between SBA and age for SBA.However,a negative and low-level correlation was observed between mSBA values and age for both reviewers.CONCLUSION SBA and mSBA measurements indicated excellent agreement regarding interobserver and intraobserver differences.The study results showed that SBA angles were reliable measurement techniques to be used on MR images.展开更多
BACKGROUND Video-capsule endoscopy(VCE)is an efficient tool that has proven to be highly useful in approaching several gastrointestinal diseases.VCE was implemented in Colombia in 2003,however current characterization...BACKGROUND Video-capsule endoscopy(VCE)is an efficient tool that has proven to be highly useful in approaching several gastrointestinal diseases.VCE was implemented in Colombia in 2003,however current characterization of patients undergoing VCE in Colombia is limited,and mainly comes from two investigations conducted before the SARS-CoV-2 pandemic period.AIM To describe the characteristics of patients undergoing VCEs and establish the main indications,findings,technical limitations,and other outstanding features.METHODS A descriptive study was carried out using data from reports of VCE(PillCam SB3 system)use in a Gastroenterology Unit in Bogotá,Colombia between September 2019 and January 2023.Demographic and clinical variables such as indication for the VCE,gastric and small bowel transit times(GTT,SBTT),endoscopic preparation quality,and limitations were described[n(%),median(IQR)].RESULTS A total of 133 VCE reports were analyzed.Most were in men with a median age of 70 years.The majority had good preparation(96.2%),and there were technical limitations in 15.8%of cases.The main indications were unexplained anemia(91%)or occult bleeding(23.3%).The median GTT and SBTT were 14 and 30 minutes,respectively.The frequencies of bleeding stigma(3.79%)and active bleeding(9.09%)were low,and the most frequent abnormal findings were red spots(28.3%),erosions(17.6%),and vascular ectasias(12.5%).CONCLUSION VCE showed high-level safety.The main indication was unexplained anemia.Active bleeding was the most frequent finding.Combined with artificial intelligence,VCE can improve diagnostic precision and targeted therapeutic interventions.展开更多
文摘目的探讨线上工作坊模式对内科专业住院医师规范化培训(简称住培)指导医师临床操作技能直接观察评估(direct observation of procedural skills,DOPS)师资培训的应用效果。方法选取2022年11月参加广东省内科专业住培普通师资培训班的45名指导医师为研究对象,采用线上分组讨论与教学视频评价反馈相结合的线上工作坊模式进行DOPS师资培训,采用问卷自评的方式评价指导医师对DOPS的掌握程度,并通过问卷调查了解培训前后指导医师对线上DOPS的培训需求与满意度。结果培训前仅17.8%的指导医师使用过DOPS量表;指导医师在培训后对DOPS的掌握程度明显高于培训前[(3.71±0.69)分比(2.29±0.87)分,P<0.01];且95.6%及以上的指导医师表示能够理解“DOPS评分项目的均质化制定方法”和“形成性反馈技巧”;100.0%的指导医师表示在今后住培教学中愿意尝试使用DOPS。课程的整体满意度评分为(8.40±1.70)分。结论线上工作坊模式对内科专业住培指导医师DOPS师资培训的短期效果满意,可进一步在住培形成性评价师资培训中推广应用。
基金the National Natural Science Foundation of China(Grant No.12072090).
文摘This paper investigates interception missiles’trajectory tracking guidance problem under wind field and external disturbances in the boost phase.Indeed,the velocity control in such trajectory tracking guidance systems of missiles is challenging.As our contribution,the velocity control channel is designed to deal with the intractable velocity problem and improve tracking accuracy.The global prescribed performance function,which guarantees the tracking error within the set range and the global convergence of the tracking guidance system,is first proposed based on the traditional PPF.Then,a tracking guidance strategy is derived using the integral sliding mode control techniques to make the sliding manifold and tracking errors converge to zero and avoid singularities.Meanwhile,an improved switching control law is introduced into the designed tracking guidance algorithm to deal with the chattering problem.A back propagation neural network(BPNN)extended state observer(BPNNESO)is employed in the inner loop to identify disturbances.The obtained results indicate that the proposed tracking guidance approach achieves the trajectory tracking guidance objective without and with disturbances and outperforms the existing tracking guidance schemes with the lowest tracking errors,convergence times,and overshoots.
文摘目的探讨基于改良Peyton四步教学法的模拟教学联合操作技能直接观察(direct observation of procedural skills,DOPS)评估方法在西藏临床技能培训中的应用效果。方法选取西藏边坝县人民医院2021年5月—2022年5月参加临床技能培训的51名医护人员为研究对象,随机分为试验组与对照组。试验组采用结合改良Peyton四步教学法进行成人男性导尿术教学,并在培训开始前、培训中期及培训结束后,由带教教师采用DOPS评估方法对学员进行测评。对照组采用传统临床技能培训方法进行教学。在培训结束后发放满意度调查问卷,以了解学员对该教学模式的满意度。结果试验组技能考核平均成绩(90.12±5.50)分,对照组技能考核平均成绩(79.36±6.95)分,两组间成绩比较,其差异具有统计学意义(P<0.001);DOPS评估量表显示,试验组学员在培训结束后临床操作各项能力均较前有显著提高,其差异均具有统计学意义(P<0.05);课后满意度调查结果显示,在赞同“增强相关基础知识”等6个方面,试验组与对照组比较,其差异均具有统计学意义(P<0.001)。结论基于改良Peyton四步教学法的模拟教学联合DOPS评估方法的教学模式可提高西藏藏区医护人员的临床技能操作水平,适合在藏区医护人员临床技能培训中推广。
文摘目的:评估操作技能直接观察评估(direct observation of procedural skills,DOPS)在血管超声技能教学中的效果。方法:选取浙江大学医学院附属第一医院超声医学2019级-2021级住培医师40名为对象。结果:三年级DOPS试验组成绩高于三年级传统对照组(P=0.048),三年级传统对照组成绩与二年级DOPS试验组差异没有统计意义(P=0.512)。结论:应用DOPS可显著提升住培医师血管超声的技能操作能力和学习效率,值得进一步研究并在住院医师规范化培训中应用。
基金partially supported by the National Natural Science Foundation of China (62322315,61873237)Zhejiang Provincial Natural Science Foundation of China for Distinguished Young Scholars(LR22F030003)+2 种基金the National Key Rearch and Development Funding(2018YFB1403702)the Key Rearch and Development Programs of Zhejiang Province (2023C01224)Major Project of Science and Technology Innovation in Ningbo City (2019B1003)。
文摘This paper proposes a new global fixed-time sliding mode control strategy for the trajectory tracking control of uncertain robotic manipulators.First,a fixed-time disturbance observer(FTDO) is designed to deal with the adverse effects of model uncertainties and external disturbances in the manipulator systems.Then an adaptive scheme is used and the adaptive FTDO(AFTDO) is developed,so that the priori knowledge of the lumped disturbance is not required.Further,a new non-singular fast terminal sliding mode(NFTSM) surface is designed by using an arctan function,which helps to overcome the singularity problem and enhance the robustness of the system.Based on the estimation of the lumped disturbance by the AFTDO,a fixed-time non-singular fast terminal sliding mode controller(FTNFTSMC)is developed to guarantee the trajectory tracking errors converge to zero within a fixed time.The settling time is independent of the initial state of the system.In addition,the stability of the AFTDO and FTNFTSMC is strictly proved by using Lyapunov method.Finally,the fixed-time NFESM(FTNFTSM) algorithm is validated on a 2-link manipulator and comparisons with other existing sliding mode controllers(SMCs) are performed.The comparative results confirm that the FTNFTSMC has superior control performance.
文摘In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated estimation guidance and control nonlinear model with limited actuator deflection angle is established considering the seeker's FOV constraint.The boundary time-varying integral barrier Lyapunov function(IBLF)is employed in backstepping design to constrain the body line-of-sight(BLOS)in IEGC system to fit a circular FOV.Then,the nonlinear adaptive controller is designed to estimate the changing aerodynamic parameters.The generalized extended state observer(GESO)is designed to estimate the acceleration of the maneuvering targets and the unmatched time-varying disturbances for improving tracking accuracy.Furthermore,the command filters are used to solve the"differential expansion"problem during the backstepping design.The Lyapunov theory is used to prove the stability of the overall closed-loop IEGC system.Finally,the simulation results validate the integrated system's effectiveness,achieving high accuracy strikes against maneuvering targets.
文摘With the increasing precision of guidance,the impact of autopilot dynamic characteristics and target maneuvering abilities on precision guidance is becoming more and more significant.In order to reduce or even eliminate the autopilot dynamic operation and the target maneuvering influence,this paper suggests a guidance system model involving a novel integral sliding mode guidance law(ISMGL).The method utilizes the dynamic characteristics and the impact angle,combined with a sliding mode surface scheme that includes the desired line-ofsight angle,line-of-sight angular rate,and second-order differential of the angular line-of-sight.At the same time,the evaluation scenario considere the target maneuvering in the system as the external disturbance,and the non-homogeneous disturbance observer estimate the target maneuvering as a compensation of the guidance command.The proposed system’s stability is proven based on the Lyapunov stability criterion.The simulations reveale that ISMGL effectively intercepted large maneuvering targets and present a smaller miss-distance compared with traditional linear sliding mode guidance laws and trajectory shaping guidance laws.Furthermore,ISMGL has a more accurate impact angle and fast convergence speed.
基金supported by the National Natural Science Foundation of China(Grant Nos.52272358 and 62103052)。
文摘This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theory,a disturbance observer with integral sliding mode and adaptive techniques is proposed to mitigate total disturbance effects,irrespective of initial conditions.By introducing an error integral signal,the dynamics of the SGGP are transformed into two separate second-order fully actuated systems.Subsequently,employing the high-order fully actuated approach and a parametric approach,the nonlinear dynamics of the SGGP are recast into a constant linear closed-loop system,ensuring that the projectile's attitude asymptotically tracks the given goal with the desired eigenstructure.Under the proposed composite control framework,the ultimately uniformly bounded stability of the closed-loop system is rigorously demonstrated via the Lyapunov method.Validation of the effectiveness of the proposed attitude autopilot design is provided through extensive numerical simulations.
基金supported by the National Natural Science Foundation of China(61873126)。
文摘In this paper,a bandwidth-adjustable extended state observer(ABESO)is proposed for the systems with measurement noise.It is known that increasing the bandwidth of the observer improves the tracking speed but tolerates noise,which conflicts with observation accuracy.Therefore,we introduce a bandwidth scaling factor such that ABESO is formulated to a 2-degree-of-freedom system.The observer gain is determined and the bandwidth scaling factor adjusts the bandwidth according to the tracking error.When the tracking error decreases,the bandwidth decreases to suppress the noise,otherwise the bandwidth does not change.It is proven that the error dynamics are bounded and converge in finite time.The relationship between the upper bound of the estimation error and the scaling factor is given.When the scaling factor is less than 1,the ABESO has higher estimation accuracy than the linear extended state observer(LESO).Simulations of an uncertain nonlinear system with compound disturbances show that the proposed ABESO can successfully estimate the total disturbance in noisy environments.The mean error of total disturbance of ABESO is 15.28% lower than that of LESO.
基金supported by the National Natural Science Foundation of China(52075476,52105065,92048302)Zhejiang Provincial Natural Science Foundation of China(LR23E050001)the Science and Technology Program of Hebei(E2021210011)。
文摘Hydraulic manipulators are usually applied in heavy-load and harsh operation tasks.However,when faced with a complex operation,the traditional proportional-integral-derivative(PID)control may not meet requirements for high control performance.Model-based full-state-feedback control is an effective alternative,but the states of a hydraulic manipulator are not always available and reliable in practical applications,particularly the joint angular velocity measurement.Considering that it is not suitable to obtain the velocity signal directly from differentiating of position measurement,the low-pass filtering is commonly used,but it will definitely restrict the closed-loop bandwidth of the whole system.To avoid this problem and realize better control performance,this paper proposes a novel observerbased adaptive robust controller(obARC)for a multi-joint hydraulic manipulator subjected to both parametric uncertainties and the lack of accurate velocity measurement.Specifically,a nonlinear adaptive observer is first designed to handle the lack of velocity measurement with the consideration of parametric uncertainties.Then,the adaptive robust control is developed to compensate for the dynamic uncertainties,and the close-loop system robust stability is theoretically proved under the observation and control errors.Finally,comparative experiments are carried out to show that the designed controller can achieve a performance improvement over the traditional methods,specifically yielding better control accuracy owing to the closed-loop bandwidth breakthrough,which is limited by low-pass filtering in fullstate-feedback control.
文摘Permanent magnet synchronous motor(PMSM)speed control systems with conventional linear active disturbance rejection control(CLADRC)strategy encounter issues regarding the coupling between dynamic response and disturbance suppression and have poor performance in suppressing complex nonlinear disturbances.In order to address these issues,this paper proposes an improved two-degree-of-freedom LADRC(TDOF-LADRC)strategy,which can enhance the disturbance rejection performance of the system while decoupling entirely the system's dynamic and anti-disturbance performance to boost the system robustness and simplify controller parameter tuning.PMSM models that consider total disturbances are developed to design the TDOF-LADRC speed controller accurately.Moreover,to evaluate the control performance of the TDOF-LADRC strategy,its stability is proven,and the influence of each controller parameter on the system control performance is analyzed.Based on it,a comparison is made between the disturbance observation ability and anti-disturbance performance of TDOF-LADRC and CLADRC to prove the superiority of TDOF-LADRC in rejecting disturbances.Finally,experiments are performed on a 750 W PMSM experimental platform,and the results demonstrate that the proposed TDOF-LADRC exhibits the properties of two degrees of freedom and improves the disturbance rejection performance of the PMSM system.
基金supported in part by the National Natural Science Foundation of China(621732556218,8101)the Shenzhen Key Laboratory of Control Theory and Intelligent Systems(ZDSYS20220330161800001)。
文摘Dear Editor,In this letter,an output tracking control problem of uncertain cyber-physical systems(CPSs)is considered in the perspective of high-order fully actuated(HOFA)system theory,where a lumped disturbance is used to denote the total uncertainties containing parameters perturbations and external disturbances.
基金supported in part by the Youth Foundation of China University of Petroleum-Beijing at Karamay(under Grant No.XQZX20230038)the Karamay Innovative Talents Program(under Grant No.20212022HJCXRC0005).
文摘The Rotary Inverted Pendulum(RIP)is a widely used underactuated mechanical system in various applications such as bipedal robots and skyscraper stabilization where attitude control presents a significant challenge.Despite the implementation of various control strategies to maintain equilibrium,optimally tuning control gains to effectively mitigate uncertain nonlinearities in system dynamics remains elusive.Existing methods frequently rely on extensive experimental data or the designer’s expertise,presenting a notable drawback.This paper proposes a novel tracking control approach for RIP,utilizing a Linear Quadratic Regulator(LQR)in combination with a reduced-order observer.Initially,the RIP system is mathematically modeled using the Newton-Euler-Lagrange method.Subsequently,a composite controller is devised that integrates an LQR for generating nominal control signals and a reduced-order observer for reconstructing unmeasured states.This approach enhances the controller’s robustness by eliminating differential terms from the observer,thereby attenuating unknown disturbances.Thorough numerical simulations and experimental evaluations demonstrate the system’s capability to maintain balance below50Hz and achieve precise tracking below1.4 rad,validating the effectiveness of the proposed control scheme.
文摘BACKGROUND Determination of platybasia and basilar kyphosis are significant parts of routine cranial magnetic resonance(MR)interpretations.These situations may explain a patient’s symptoms or may be associated with other anomalies.AIM To indicate the interobserver and intraobserver reliability of the skull base angles(SBA)(Koenigsberg standard)and modified SBA(mSBA)measurement techniques.METHODS In total,391 patients who had undergone cranial MR imaging were re-assessed regarding the SBA measurements.The SBA and mSBA techniques were used on MR images.Two reviewers independently measured the same angles twice within a 15-day interval,using different monitors.Intraclass correlation coefficient(ICC)was calculated to reveal the intraobserver and interobserver agreements.RESULTS There was an excellent agreement between reviewers regarding both angle measurements(ICC was 0.998 for SBA and mSBA).Excellent agreement levels were also observed for intraobserver measurements.ICC was 0.998 for SBA and 0.999 for mSBA for reviewer 1.ICC was 0.997 for SBA and 0.999 for mSBA according to the measurement results of reviewer 2.Higher SBA and mSBA values were observed for females compared to males.There was no correlation between SBA and age for SBA.However,a negative and low-level correlation was observed between mSBA values and age for both reviewers.CONCLUSION SBA and mSBA measurements indicated excellent agreement regarding interobserver and intraobserver differences.The study results showed that SBA angles were reliable measurement techniques to be used on MR images.
文摘BACKGROUND Video-capsule endoscopy(VCE)is an efficient tool that has proven to be highly useful in approaching several gastrointestinal diseases.VCE was implemented in Colombia in 2003,however current characterization of patients undergoing VCE in Colombia is limited,and mainly comes from two investigations conducted before the SARS-CoV-2 pandemic period.AIM To describe the characteristics of patients undergoing VCEs and establish the main indications,findings,technical limitations,and other outstanding features.METHODS A descriptive study was carried out using data from reports of VCE(PillCam SB3 system)use in a Gastroenterology Unit in Bogotá,Colombia between September 2019 and January 2023.Demographic and clinical variables such as indication for the VCE,gastric and small bowel transit times(GTT,SBTT),endoscopic preparation quality,and limitations were described[n(%),median(IQR)].RESULTS A total of 133 VCE reports were analyzed.Most were in men with a median age of 70 years.The majority had good preparation(96.2%),and there were technical limitations in 15.8%of cases.The main indications were unexplained anemia(91%)or occult bleeding(23.3%).The median GTT and SBTT were 14 and 30 minutes,respectively.The frequencies of bleeding stigma(3.79%)and active bleeding(9.09%)were low,and the most frequent abnormal findings were red spots(28.3%),erosions(17.6%),and vascular ectasias(12.5%).CONCLUSION VCE showed high-level safety.The main indication was unexplained anemia.Active bleeding was the most frequent finding.Combined with artificial intelligence,VCE can improve diagnostic precision and targeted therapeutic interventions.