A novel reaching law approach of quasi-sliding-mode control for uncertain discrete-time systems

A novel discrete-time reaching law was proposed for uncertain discrete-time system,which contained process noise and measurement noise.The proposed method reserves all the advantages of discrete-time reaching law,which not only decreases the band width of sliding mode and strengthens the system robustness,but also improves the dynamic performance and stability capability of the system.Moreover,a discrete-time sliding mode control strategy based on Kalman filter method was designed,and Kalman filter was employed to eliminate the influence of system noise.Simulation results show that there is no chattering phenomenon in the output of controller and the state variables of controlled system,and the proposed algorithm is also feasible and has strong robustness to external disturbances.

Reaching law based sliding mode control for a frame structure under seismic load

Implementation of efficient vibration control schemes for seismically excited structures is becoming more and more important in recent years.In this study,the influence of different control schemes on the dynamic performance of a frame structure excited by El Centro wave,with an emphasis on reaching law based control strategies,is examined.Reaching law refers to the reachable problem and criteria for the sliding state of a control system.Three reaching laws are designed to present different sliding mode control strategies by incorporating a state space model that describes structural dynamic characteristics of a frame structure.Both intact and damaged structures are studied by using the aforementioned control strategies.The influence of different structural damage extents,control locations and reaching law based control methods are further investigated.The results show that the structure can be well controlled using the sliding mode strategy when the induced structural damage extent does not exceed the standard percentage for considering the structure was damaged,which is 20%reduction in structure stiffness,as reported in the literature.The control effectiveness is more satisfactory if the control location is the same as the direction of external excitation.Furthermore,to study the chattering phenomenon of the sliding mode control method,approximation and detail components extracted from the phase plots of the sliding mode control system are compared via wavelet transform at different scales.The results show that for the same type of control law,the system behaves with similar chattering phenomenon.

Sliding mode control of three-phase AC/DC converters using exponential rate reaching law

Sliding mode control(SMC) becomes a common tool in designing robust nonlinear control systems, due to its inherent characteristics such as insensitivity to system uncertainties and fast dynamic response.Two modes are involved in the SMC operation, namely reaching mode and sliding mode.In the reaching mode, the system state is forced to reach the sliding surface in a finite time.The major drawback of the SMC approach is the occurrence of chattering in the sliding mode, which is undesirable in most applications.Generally, the trade-off between chattering reduction and fast reaching time must be considered in the conventional SMC design.This paper proposes SMC design with a novel reaching law called the exponential rate reaching law(ERRL) to reduce chattering, and the control structure of the converter is designed based on the multiinput SMC that is applied to a three-phase AC/DC power converter.The simulation and experimental results show the effectiveness of the proposed technique.

Normalizing the Arm Reaching Patterns after Stroke through Forced Use Therapy– A Systematic Review

Hemiparesis is common following stroke. The ability to reach and grasp is a necessary component of many daily life functional tasks, hence reduced upper limb function has an impact on the ability to perform activities of daily living. In hemiparetic patients, the unrestricted and unguided repetition of a motor task may reinforce compensatory movements. Trunk restraint allowed the patients to use joint ranges that were present but not recruited during unrestrained reaching. Later, studies combined the trunk restraint training with additional therapeutic interventions. With the growing number of studies on this intervention in the stroke population, there is the need to consolidate this evidence to determine the potential use of trunk restraint training in improving arm reaching in neurological rehabilitation particularly for stroke patients. A considerable research effort had assessed the effects of trunk restraint training on the recovery of reaching movements in hemiparetic patients. This review identified 5 relevant trials in which one trial is a pilot study. Among 5 trials, three trials recorded the movement kinematics (outcome measure) by Optotrak Motion analysis System, in the other two trials the movement kinematics (outcome measure) were analysed by a 6 – camera, 3D Motion analysis system and 10 – camera Motion Analysis System respectively. The effect size for the intervention was calculated by Cohen’s d. In this review, for the meta-analysis we used trunk displacement, trunk flexion, elbow extension, Smoothness and hand trajectory straightness (movement variables in kinematic analysis). The results of our review demonstrated that the use of trunk restraint as a treatment paradigm aimed at decreasing compensatory strategies has the potential of becoming an effective therapy. Further studies are necessary to determine the long term effect of the trunk restraint training.

Reaching for the Stars

I paid great attention to the Alibaba program that nurtures entrepreneurs. We must conduct dialogue with African governments, so that they support young entrepreneurs and cultivate ecommerce systems.＂ These are the words of Dr. Mukhissa Kituyi, secretary general of the United Nations Conference on Trade and Development （UNCTAD）, who paid a visit to the headquarters of the Alibaba Group on June 28, 2018 to speak with 29 African entrepreneurs, who were receiving training under the “African Entrepreneur Training Program.”

Responses of Climatic Change on the Lagging Time about Ground Temperature Reaching the Extremum at Shallow Layers Soil in Wuli

The air temperature of Wuli,which is located in seasonal frozen ground zone,is rising by 13 ℃ yearly.This paper discusses the days that each ground layers' temperature lags behind the surface temperature in reaching extremum.The results were shown:The time of each ground layers' lagging days was increasing;the lagging day in warm season was longer than that in cold season;the growth rate of lagging days in warm season was 0.5 d/y,while the growth rate of lagging days in cold season was 0.7 d/y.

Reaching the People

CHINESE and Nigerian media should be aware of their growing influence at home and abroad and should strive to present unbiased news coverage, including stories about each other＇s respective country. Agreement on this important step in ongoing cooperation between the two sides was reached by media representatives attending a me- dia forum on September 19 in Abuja, Nigeria.

REACHING OUT FOR COMMON DEVELOPMENT The Chinese Enterprise Global Image Summit calls for cooperation in overseas markets

To foster a new development paradigm with domestic circulation as the core and domestic and international circulations reinforcing each other,Chinese enterprises are undertaking a lead role in making better use of both domestic and international markets and resources to achieve stronger and more sustainable development and promote construction of an open world economy.Considering the new paradigm,how should Chinese enterprises further develop in the overseas markets?At the Chinese Enterprise Global Image Summit 2020 held in Beijing on November 3,representatives from government departments,business companies,think tanks,and media outlets shared strategies.

REACHING PAST LUNAR LIMITS

Chaqg'e is the Chinese moon goddess.Named after'her,the Chang'e-6 lunar module returned to Earth this June carrying 1,935.3 grams of rocks and dust from the far side of the moon.A world first,the unique samples-more viscous and clumpier than previously collected lunar specimens-will be distributed globally for scientific analysis.

Quality of life and aging

The aging population has far-reaching implications for health,significantly influencing medical care and health policy.According to the World Health Organization(WHO),by 2030,one in six people worldwide will be aged 60 years or older.Furthermore,the population of individuals aged 60 and older is projected to increase from 1 billion in 2020 to 1.4 billion in 2030.By 2050,this population is expected to double,reaching 2.1 billion.Similarly,the number of people aged 80 years and older is anticipated to triple between 2020 and 2050,reaching 426 million[1].This demographic shift toward older adults,known as population aging,initially began in high-income countries but has now extended to low and middle-income nations.By 2050,approximately two-thirds of the world’s population aged 60 and older will reside in these countries.The effects of this aging population pose significant challenges for human health,necessitating substantial societal adjustments[2].

Quantifying Kinematic Tremor in an NGLY1-Deficient Individual: A Case Study

NGLY1 Deficiency is an autosomal recessive congenital disorder that has been identified in less than 100 individuals. Most individuals with NGLY1 Deficiency display hyperkinetic movement disorders, including choreiform, athetoid, dystonic myoclonic, dyskinetic, and dysmetric movements. Developing a consistent and concise consensus on the classification and evaluation of tremors is essential to forward the research and treatment of tremors. It has also been reported that some individuals with NGLY1 Deficiency demonstrate tremor, but such tremor has never been formally investigated. The primary objective of this study is to determine if an individual with NGLY1 Deficiency demonstrates an identifiable tremor during a series of arm movements and, if so, describe the frequency and power characteristics of that tremor. Arm movement kinematics were obtained using a 16-camera Vicon system, and time series trajectory waveforms for three planes of a marker placed on the hand were developed. Custom MATLAB scripts were utilized to compute Fast Fourier Transformations of the data within the identified waveform segments. A mean frequency of 2.30 Hz (SD = 1.05) with a mean power of 5.02 |P1(f)| (SD = 4.63) suggests that our participant’s kinematic data did display a persistent tremor in both hands across all tasks and movement planes. Analyses of the reaching hand and the non-reaching hand suggest the participant displayed an action tremor in both postural and intention (kinetic) tremors. Future directions should include assessing additional individuals with NGLY1 Deficiency to determine if the tremor is a distinguishable disorder behavior. Additionally, evaluating other anatomical sites, such as the elbow, head, and lower limbs, would provide further insights into the characteristics of this tremor.

PRAYERS FROM A CATHOLIC CHURCH BY THE LANCANGJIANG RIVER IN CHAMDO

It was 18:59.Sister Magdalene rose from her chair by the front gate of the churchandwalked towards thebell tower.Leaning to one side,Magdalene grasped the rope with her right hand while reaching into herpocket withher left,pulling out hercellphoneto check the time once more-7:00 p.m.

用关爱和包容建设儿童青少年的心理安全网——新加坡儿童青少年心理健康服务研究

儿童青少年的心理健康成为新加坡社会特别关注的问题。文章概括了新加坡儿童青少年心理健康状况,梳理了新加坡心理健康政策发展历程,重点论述了新加坡学校、家庭、社会组织的针对性心理健康服务。新加坡通过多方联动的REACH模式对儿童青少年的心理健康进行干预,利用信息化手段应对新冠疫情带来的心理危机并助力心理健康服务创新发展,努力为儿童青少年的健康发展构建充满关爱与温暖的安全网,为世界贡献了新加坡经验。

Mid-infrared Er：ZBLAN fiber laser reaching 3.68 μm wavelength

We report a continuous-wave Er：ZBLAN fiber laser with the operation wavelength reaching 3.68 μm.The midinfrared Er：ZBLAN fiber laser is pumped with the dual-wavelength sources consisting of a commercial laser diode at 970 nm and a homemade Tm-doped fiber laser at 1973 nm.By increasing the launched pump power at1973 nm,the laser wavelength can be switched from 3.52 to 3.68 μm.The maximum output power of 0.85 W is obtained with a slope efficiency of 25.14% with respect to the 1973 nm pump power.In the experiment,the laser emission at 3.68 μm is obtained with a significant power of 0.62 W,which is the longest emission wavelength in free-running Er：ZBLAN fiber lasers.

Bio-inspired motion planning for reaching movement of a manipulator based on intrinsic tau jerk guidance

This study proposed a bio-inspired motion planning approach for the reaching movement of a robot manipulator based on a novel intrinsic tau jerk guidance strategy,which was established by some cognitive science researchers when they studied motion patterns through biology.In accordance with the rules of human reaching movement,the intrinsic tau jerk guidance strategy ensures continuity of the acceleration;further,it also ensures that its value is zero at the start and end of the movement.The approach has been implemented on a three-degrees-offreedom 3R planar manipulator.The results show that,within a defined time,both the position gap and attitude gap can be reposefully closed,and the curves of joint velocity,acceleration,and driving torque are continuous and smooth.According to the dynamic analysis,the proposed approach tends to consume less energy.The bioinspired method has the potential to be applied in particular scenarios in the future,such as a mobile robot with a manipulator exploring an unknown environment.

A modified forward and backward reaching inverse kinematics based incremental control for space manipulators

Forward and backward reaching inverse kinematics(FABRIK)is an efficient two-stage iterative solver for inverse kinematics of spherical-joint manipulator without the calculation of Jacobian matrix.Based on FABRIK,this paper presents an incremental control scheme for a free-floating space manipulator consists of revolute joints and rigid links with the consideration of joint constraints and dynamic coupling effect.Due to the characteristics of FABRIK,it can induce large angular movements on specific joints.Apart from that,FABRIK maps three dimensional(3D)problem into two dimensional(2D)problem by a simple geometric projection.This operation can cause infinite loops in some cases.In order to overcome these issues and apply FABRIK on space manipulators,an increments allocation method is developed to constrain the angular movements as well as to re-orient the end-effector.The manipulator is re-positioned based on the momentum conservation law.Instead of pure target position tracking,the orientation control of the end-effector is also considered.Numerical simulation is performed to testify and demonstrate the effectiveness and reliability of the proposed incremental control approach.

Reaching a few 10-15 long-term stability of integrating sphere cold atom clock

We present the long-term stability of the integrating sphere cold atom clock（ISCAC） and analyze its systematic limitations. The relative frequency instability of 2.6 × 10-15 is reached for an averaging time of 2 ×105 s. The second-order Zeeman effect and the cavity pulling effect in ISCAC, which would induce the frequency drift from the clock transition, are analyzed. The analytical and experimental results indicate that the cavity pulling effect is the main contribution to the long-term frequency instability of the ISCAC. Further technical improvements to the microwave cavity are also discussed.

Discrete-time sliding mode control with power rate exponential reaching law of a pneumatic artificial muscle system

This paper develops a discrete-time sliding mode controller with a power rate exponential reaching law approach to enhance the performance of a pneumatic artificial muscle system in both reaching time and chattering reduction.The proposed method dynamically adapts to the variation of the switching function,which is based on an exponential term and a power rate term of the sliding surface.Thus,the controlled system can achieve high tracking performance while still obtain chattering-free control.Moreover,the effectiveness of the proposed method is validated through multiple experimental tests,focused on a dual pneumatic artificial muscle system.Finally,experimental results show the effectiveness of the proposed approach in this paper.

Sliding mode controller design based on reaching law for hypersonic flight vehicle

or a hypersonic flight vehicle with highly coupling nonlinear,a sliding mode controller based on reaching law is designed for its longitudinal motion model.Two proposals of reaching law are designed.One of which is a variable exponential reaching law,the other one is compound reaching law which consists of a conventional exponential reaching law and a power rate reaching law.The reaching law controller can speed up the system states arriving at the sliding mode condition,at the same time,it can guarantee better robustness.Simulation analysis is conducted for trimmed cruise condition of 110,000 ft and Mach 15,in which the responses of the vehicle to a step change of altitude and velocity respectively are analyzed.Simulation results show that the controller based on variable exponential reaching law enables the system to faster tracking speed than the conventional reaching law.Moreover the compound reaching law controller has shorter tracking time and strong robustness against parameters uncertainties.

汽车产品应对韩国回收及禁限用物质法规策略探讨

文章针对汽车产品出口韩国所需应对的回收及禁限用物质法规(韩国ELV,韩国REACH,韩国BPR,韩国GHS)进行梳理,探讨韩国市场相关的法规要求,以及应对策略,规避汽车产品出口韩国市场不合规风险。