Effects of Joint Controller on Analytical Modal Analysis of Rotational Flexible Manipulator

Modal analysis is a fundamental and important task for modeling and control of the flexible manipulator. However, almost all of the traditional modal analysis methods view the flexible manipulator as a pure mechanical structure and neglect feedback action of joint controller. In order to study the effects of joint controller on the modal analysis of rotational flexible manipulator, a closed-loop analytical modal analysis method is proposed. Firstly, two exact boundary constraints, namely servo feedback constraint and bending moment constraint, are derived to solve the vibration partial differential equation. It is found that the stiffness and damping gains of joint controller are both included in the boundary conditions, which lead to an unconventional secular term. Secondly, analytical algorithm based on Ritz approach is developed by using Laplace transform and complex modal approach to obtain the natural frequencies and mode shapes. And then, the numerical simulations are performed and the computational results show that joint controller has pronounced influence on the modal parameters： joint controller stiffness reduces the natural frequency, while joint controller damping makes the shape phase non-zero. Furthermore, the validity of the presented conclusion is confirmed through experimental studies. These findings are expected to improve the performance of dynamics simulation systems and model-based controllers.

MODELING AND CONTROLLING OF PARALLEL MANIPULATOR JOINT DRIVEN BY PNEUMATIC MUSCLES

A parallel manipulator joint driven by three pneumatic muscles and its posture control strategy are presented. Based on geometric constraints and dynamics, a system model is developed through which some influences on dynamic response and open-loop gain are analyzed including the supply pressure, the initial pressure and the volume of pneumatic muscle. A sliding-mode controller with a nonlinear switching function is applied to control posture, which adopts the combination of a main method that separates control of each muscle and an auxiliary method that postures error evaluation of multiple muscles, especially adopting the segmented and intelligent adjustments of sliding-mode parameters to fit different expected postures and initial states. Experimental results show that this control strategy not only amounts to the steady-state error of 0. 1° without overshoot, but also achieves good trajectory tracking.

Joint space compliance control for a hydraulic quadruped robot based on force feedback

In the realm of quadruped robot locomotion,compliance control is imperative to handle impacts when negotiating unstructured terrains.At the same time,kinematic tracking accuracy should be guaranteed during locomotion.To meet both demands,ajoint space compliance controller is designed,so that compliance can be achieved in stance phase while position tracking performance can be guaranteed in swing phase.Unlike operational space compliance control,the joint space compliance control method is easy to implement and does not depend on robot dynamics.As for each joint actuator,high performance force control is of great importance for compliance design.Therefore,a nonlinear PI controller based on feedback linearization is proposed for the hydraulic actuator force control.Besides,an outer position loop（compliance loop）is closed for each joint.Experiments are carried out to verify the force controller and compliance of the hydraulic actuator.The robot leg compliance is assessed by a virtual prototyping simulation.

Regional Coordinated Development and Joint Prevention and Control for Environmental Protection in China in the New Era

The three important historical development stages of China from"standing up","getting rich"to"becoming strong"were analyzed deeply.Regional coordinated development policies and strategies have also gone through the"enlightenment stage","development stage"and"mature stage".On this basis,the problems of the coordination of China s regional coordinated development and joint prevention and control for environmental protection in the new era,as well as suggestions for the next step were further analyzed.

Anti-Windup Control Strategy of Drive System for Humanoid Robot Arm Joint

To address the problems of torque limit and controller saturation in the control of robot arm joint,an anti-windup control strategy is proposed for a humanoid robot arm,which is based on the integral state prediction under the direct torque control system of brushless DC motor. First,the arm joint of the humanoid robot is modelled. Then the speed controller model and the influence of the initial value of the integral element on the system are analyzed. On the basis of the traditional antiwindup controller,an integral state estimator is set up. Under the condition of different load torques and the given speed,the integral steady-state value is estimated. Therefore the accumulation of the speed error terminates when the integrator reaches saturation. Then the predicted integral steady-state value is used as the initial value of the regulator to enter the linear region to make the system achieve the purpose of anti-windup. The simulation results demonstrate that the control strategy for the humanoid robot arm joint based on integral state prediction can play the role of anti-windup and suppress the overshoot of the system effectively. The system has a good dynamic performance.

An Innovative Mechanism of Blockchain Technology on Joint Governance Model

Joint prevention and control is a social organization model dealing with the governance of public health and security incidents.The governance models should have the features of multiple subjects co-governing and distributed cooperating.Their purposes are to solve and improve the governance efficiency of dealing with public health and security incidents at the executive level.However,there are still many deficiencies in the current data governance and collaborative governance of joint prevention and control systems,which are mainly reflected in incomplete data collection,unimpeded data sharing,inflexible collaborative cooperation,and inadequate collaborative supervision.Therefore,a new innovative governance model is urgently needed.Blockchain technology is suitable for implementing multiparty data sharing and cooperation,and at the same time,it supports penetrating supervision and management.This paper studies the blockchain model for joint governance of public health and security incidents.It focuses on the multiagent collaborative prevention and control governance model,which provides a new opportunity for model innovation in data governance and in cooperative governance.

上海市新型冠状病毒肺炎防控策略探讨

根据政府公开发布的数据和相关的媒体报道,分析归纳上海市新型冠状病毒肺炎疫情防控方略,探讨超大城市应对突发传染病的防控经验和策略。上海市通过居家隔离、联防联控、群防群治、信息公开和分级复工等防控措施,成功将新型冠状病毒肺炎患者人数控制在1641人(截至2021年1月24日),占全国累计确诊病例数的1.64%,防控效果显著。上海市有效地控制了疫情蔓延,为超大城市应对突发急性传染病等公共卫生事件提供了极有价值的经验和策略。

Ecological and Environmental Protection Requirements in China s Regional Coordinated Development Strategy in the New Era

Starting from the historical evolution of China s regional coordinated development policy and practice,three stages of"enlightenment stage","development stage"and"maturity stage",as well as the connotation,characteristics and content of implementing regional coordinated development strategy were analyzed.On this basis,from different aspects of industrial distribution,pollutant characteristics and regional environmental protection policy,the existing ecological and environmental protection problems in China s regional coordinated development in the new era were analyzed,and some suggestions for the next step were put forward.It is necessary to follow the"four ones"concept from the overall point of view,implement"three lines and one list"from the perspective of the width of the access red line,strengthen"joint prevention and control"from the perspective of the depth of regional regulation,deepen the"planning environmental impact assessment"from the perspective of the breadth of industrial distribution,and promote the"green-way model"from the perspective of ecological low carbon.

Research on Decision Model of Control over Technology Standard Alliance

Technology standard alliance, as vectors of research, development and circulation for technology standard, has already become an important transformation form from laboratory standard to fact standard for all countries. However, during the process of forming the technology standard alliance, it is a focus for members in the alliance to take control over others. How to construct a scientific and reasonable decision model of control over technology standard alliance is closely related to each enterprise member＇s interest. Under the condition that the risk is neutral, the paper explored necessary and sufficient conditions of knowledge sharing and the most endeavor among enterprise members through constructing a decision model of control over technology standard alliance, and put forward that the joint control model was the best decision model for constructing the technology standard alliance.

Sliding Mode and PI Controllers for Uncertain Flexible Joint Manipulator

This paper is dealing with the problem of tracking control for uncertain flexible joint manipulator robots driven by brushless direct current motor(BDCM). Flexibility of joint in the manipulator constitutes one of the most important sources of uncertainties. In order to achieve high performance, all parts of the manipulator including actuator have been modeled. To cancel the tracking error, a hysteresis current controller and speed controllers have been developed. To evaluate the effectiveness of speed controllers, a comparative study between proportional integral(PI) and sliding mode controllers has been performed. Finally, simulation results carried out in the Matlab simulink environment demonstrate the high precision of sliding mode controller compared with PI controller in the presence of uncertainties of joint flexibility.

An assessment of China's joint prevention and control policy on sulfur dioxide emissions reduction:A spatial econometric analysis

Sulfur dioxide(SO_(2))is a typical pollutant that affects human health,climate,and environmental and ecological conditions.China has been experiencing high concentrations of SO_(2),particularly in urban areas,since the 1990s.In 2010,a"joint prevention and control"(JPC)policy was issued to address air pollution problems and strengthen the regulation of SO_(2)emissions.This study aimed to describe the mitigation effects of this policy on SO_(2)emissions in 116 Chinese cities from 2003 to 2017.We applied global and local Moran's I indices to confirm the presence of significant spatial autocorrelation in SO_(2)emissions and constructed four spatial models to assess the effect of the JPC policy in reducing SO_(2)emissions and its transmission mechanism.We found that the policy decreased SO_(2)emissions by 1.89×10^(4)tons,S0_(2)intensity by 1.70 tons per km^(2),and S0_(2)per capita of 158.49 tons per 10,000 people in each city,on average,all of which are significant changes.The empirical results also show that population growth,economic structure,and environmental protection significantly decrease SO_(2)emissions.Finally,we recommended policies to encourage regional cooperation under the JPC policy,with the aim of promoting furtherreductions in SO_(2)emissions.

Environmental options of local governments for regional air pollution joint control:application of evolutionary game theory

Apanage management is currently the main method used to control air pollution in China,but it has proved to be inefficient for controlling transboundary air pollution.As a result,China’s central government is demanding joint control of regional air pollution.From the perspective of cooperation benefits,we adopt the evolutionary game theory(EGT)to analyse evolutionary trends of regional authorities’behaviours and their stable strategy in the campaign for joint control of regional air pollution.A case study,the intergovernmental cooperation management for‘APEC Blue’,is taken to illustrate the intergovernmental game.The result shows that an evolutionarily stable strategy(ESS)of‘joint control’for local governments depends on individual region’s benefits and collaboration revenues.Local governments should be encouraged in collaborating with their neighbouring governments,because a certain amount of transaction costs will not undermine their cooperation.With regards to the case study,joint control through executive orders is unpractical in the Beijing–Tianjin–Hebei region.‘APEC Blue’can only be temporary and the failure of such collaboration for long-term regional air pollution control is inevitable because of its high control costs,economic loss,transaction costs and low common profits.

Optimal Control Policy of M/G/1 Queueing System with Delayed Randomized Multiple Vacations Under the Modified Min(N,D)-Policy Control

Based on the number of customers and the server’s workload,this paper proposes a modified Min(N,D)-policy and discusses an M/G/1 queueing model with delayed randomized multiple vacations under such a policy.Applying the well-known stochastic decomposition property of the steady-state queue size,the probability generating function of the steady-state queue length distribution is obtained.Moreover,the explicit expressions of the expected queue length and the additional queue length distribution are derived by some algebraic manipulations.Finally,employing the renewal reward theorem,the explicit expression of the long-run expected cost per unit time is given.Furthermore,we analyze the optimal policy for economizing the expected cost and compare the optimal Min(N,D)-policy with the optimal N-policy and the optimal D-policy by using numerical examples.

Autonomic Performance and Power Control on Virtualized Servers:Survey, Practices, and Trends

Modern datacenter servers hosting popular Internet services face significant and multi-facet challenges in performance and power control. The user-perceived performance is the result of a complex interaction of complex workloads in a very complex underlying system. Highly dynamic and bursty workloads of Internet services fluctuate over multiple time scales, which has a significant impact on processing and power demands of datacenter servers. High-density servers apply virtualization technology for capacity planning and system manageability. Such virtuMized computer systems are increasingly large and complex. This paper surveys representative approaches to autonomic performance and power control on virtualized servers, which control the quality of service provided by virtualized resources, improve the energy efficiency of the underlying system, and reduce the burden of complex system management from human operators. It then presents three designed self-adaptive resource management techniques based on machine learning and control for percentile-based response time assurance, non-intrusive energy-efficient performance isolation, and joint performance and power guarantee on virtualized servers. The techniques were implemented and evaluated in a testbed of virtualized servers hosting benchmark applications. Finally, two research trends are identified and discussed for sustainable cloud computing in green datacenters.

Prevention and control of zoonoses at their source:from the Chinese perspective

Zoonoses are a significant public health concern and cause considerable socioeconomic problems globally.The emergence of severe acute respiratory syndrome(SARS),highly pathogenic avian influenza(HPAI),and Ebola virus disease(EVD)has had a significant effect on the national economy and public health in China,and other countries.This review analyzed zoonotic disease issues faced by China,and the main factors contributing to the risk of zoonotic disease.The Chinese government has devised new strategies and has taken measures to deal with the challenges of these diseases,and the prevention and control of zoonoses at their source.A strategy that is suited to China’s national conditions,is proposed.