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.

Distinct element modelling of fracture plan control in continuum and jointed rock mass in presplitting method of surface mining

Controlled blasting techniques are used to control overbreak and to aid in the stability of the remaining rock formation. Presplitting is one of the most common methods which is used in many open pit mining and surface blast design. The purpose of presplitting is to form a fracture plane across which the radial cracks from the production blast cannot travel. The purpose of this study is to investigate of effect of presplitting on the generation of a smooth wall in continuum and jointed rock mass. The 2D distinct element code was used to simulate the presplitting in a rock slope. The blast load history as a function of time was applied to the inner wall of each blasthole. Important parameters that were considered in the analysis were stress tensor and fracturing pattern. The blast loading magnitude and blasthole spacing and jointing pattern were found to be very significant in the final results.

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.

A novel adaptive joint power control algorithm with channel estimation in a CDMA cellular system

Joint power control has advantages of multi-user detection and power control; and it can combat the multi-access interference and the near-far problem. A novel adaptive joint power control algorithm with channel estimation in a CDMA cellular system was designed. Simulation results show that the algorithm can control the power not only quickly but also precisely with a time change. The method is useful for increasing system capacity.

Research on Precision Assembly Robot's Joint Torque Control Based on Current Measurement

A set of new current sensing device is used to realize joint torque control based on current measurement in a precision assembly robot's third joint. The output torque's model of the joint's brushless DC motor is founded. Disturbance factors and the compensated effect of the torque's closed loop based on current measurement are analyzed. Related simulations and experiments show that the system has good current tracking and anti-disturbances performance, which improve the force control performance of the robot in assembly.

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.

Interval Type-2 Fuzzy PD Tracking Control of Flexible-Joint Robots

This paper develops a novel interval type-2 fuzzy Proportional-Derivative (PD) control scheme for electrically driven flexible-joint robots using the direct method of Lyapunov. The controller has a simple design in a decentralized structure. Compared to the previous controllers reported for the flexible-joint robots which use two control loops, it has a simpler structure using only one control loop. It guarantees stability and provides a good tracking performance. The controller considers the whole robotic system including the manipulator and motors by applying the voltage control strategy. Stability analysis is presented and the effectiveness of the proposed control approach is demonstrated by simulations using a three link flexible-joint robot driven by permanent magnet DC motors. Simulation results show that the interval type-2 fuzzy PD controller can handle external disturbance better than the type-1 fuzzy PD controller. In addition, it spends less control effort than the type-1 in order to deal with disturbance.

Diagnostic Sacroiliac Joint Injections: Is a Control Block Necessary?

Background: Sacroiliac joint (SIJ) pain presents as a deep and somatic pain, predominantly affecting the lower back and buttock and referring down the leg, sometimes as far as the foot. Given that the features of SIJ pain are non-specific and that this referred pain is similar to lumbar facet joint and lumbar disc pain, diagnostic local anesthetic injections (diagnostic blocks) into the SIJ are used to identify the source of pain. Despite wide use, little is known about the false positive rate of a single diagnostic sacroiliac (SI) block and the requirement for a control block. Objective: To determine whether a control SI block is necessary and to monitor the false positive rate for a single injection. Study Design: A prospective and observational study was conducted as part of a practice audit, with data collected over 3.5 years at the authors’ private practice. Patients & Methods: Under fluoroscopic guidance, 1408 consecutive patients presenting with prominent deep somatic pain over the SIJ region were sterilely injected with anesthetic into the SIJ and/or the deep interosseous ligament (DIL). Pain was measured on the 11-point Numerical Rating Scale (NRS) prior to injection and incrementally over the following 1- 2 weeks. Fully completed and unequivocal data sets were available for 1060 patients. Decreases in pain scores (of >80%) at >2 hours of post-injection were indicative of SIJ pain and recorded as a positive SIJ block. Results: Of 1060 patients receiving a first SIJ diagnostic block, 680 (64.1%) recorded a positive result. Subsequently, 271 positive patients and 22 who were negative for SIJ pain opted to receive a second control block. SIJ pain diagnosis was confirmed in 237/271 (87.5%) of those with an initial positive response, while 18/22 patients (81%) had their initial negative result confirmed. The false positive rate of a single block is therefore calculated at 12.5%, and on a contingency table analysis, a single anesthetic SIJ injection has diagnostic accuracy of 87.03%, with high sensitivity (98.3%), when compared with a second control diagnostic block. Limitations: All injections were performed at one clinical centre. A proportion (348/1408) of initial patients did not return fully completed pain records or had equivocal responses (≥80% pain relief, but transiently, for ≤30 min) and were excluded from further analysis. Conclusion: Given the observed high rates of accuracy in this study, it is reasonable to suggest the use of one diagnostic block as the criterion standard for assessing the SIJ as the source of a patient’s pain.

Joint Resource Allocation and Admission Control Mechanism in Software Defined Mobile Networks

This paper presented a joint resource allocation(RA) and admission control(AC) mechanism in software defined mobile networks(SDMNs). In this mechanism, the joint RA and AC problem can be formulated as an optimization problem with the aim of maximizing the number of admitted users while simultaneously minimizing the number of allocated channels. Since the primal problem is modeled to be a mixed integer nonlinear problem(MINLP), we attain the suboptimal solutions to the primal MINLP by convex relaxation. Additionally, with the global information collected by the SDMNs controller, a centralized joint RA and AC(CJRA)algorithm is proposed by the Lagrange dual decomposition technique to obtain the global optimum. Meanwhile, we propose an OpenFlow rules placement strategy to realize CJRA in an efficient way. Moreover, a distributed algorithm is also developed to find the local optimum, showing a performance benchmark for the centralized one. Finally, simulation results show that the proposed centralized algorithm admits more users compared with the distributed.

Design of Robust Controller for Flexible Joint Robot with Nonlinear Friction Characteristics

A robust controller method for flexible joint robot considering the effect caused by nonlinear friction was presented.The nonlinear friction was denoted as inverse additive output uncertainty relative to the nominal model in our work,based on which the describing function was analyzed in frequency domain,and the weighting function of nonlinear friction was further calculated as well. By combining the friction uncertainty,the mixed sensitivity H∞optimization was proposed as the benchmark for controller design, which also leaded to good performance of robustness. Furthermore,unstructured perturbation to the system was analyzed so that the stability was guaranteed. Simulation results show that the proposed controller can provide excellent tracking and regulation performance.

可调桨系统机桨联控节油技术研究

随着全球能源危机的日益严峻,EEDI(新船能效设计指数)的提出和不断普及,以及IMO(国际海事组织)对于船舶废气排放要求的日益严苛,燃油消耗成为了考核船舶性能的重要指标。“节油模式”机桨匹配过程方法,以主机燃油耗油量为目标值,通过研究主机的万有特性、桨的效率特性,以及船机桨匹配的特点,寻找在不同目标航速下油耗最低时的机桨匹配工况点;通过与传统可调桨控制模式相比较,验证了其节油效果。对于船舶节能系统的研究设计提供了技术储备,对于可调桨“节油模式”遥控系统的研发极具指导意义。

深部矿井软底回采巷道底鼓机理及防治研究

针对山阳煤矿软底回采巷道严重底鼓的难题,采用理论分析、数值模拟和现场应用的方法,基于塑性理论建立了巷道底板岩体滑移线底鼓力学模型。研究表明,巷道底板破坏岩体主要分为3个区,分别为主动极限区、过渡区和被动极限区,推导了巷道底板岩体的最大破坏深度,提出了锚索+卸压槽联合控制底鼓的方法。采用数值模拟的方法验证了联合控制方案的可行性,现场应用效果表明该方法能够有效控制软底巷道底鼓,为相似地质条件底鼓问题的研究提供了一定的帮助。

数字孪生城区防洪排涝及活水自流联控联调平台开发与应用

为响应数字中国战略与数字孪生水利建设,数字赋能提升河网水工程安全运行监控和智能化、精细化管理水平,以苏州高新区为例,分析了数字孪生平台建设需求,提出了包含防洪排涝、水环境保障、水工程管理综合业务的平台建设总体架构。根据研究区已有的基础数据、监测数据、业务数据等数据基础,采用“数字孪生技术+BIM(Building Information Modeling,建筑信息模型)”核心应用技术搭建了平台的数据底板,集成建设了模型平台、孪生融合、知识平台与数字孪生场景,基于算据、算法、算力支撑构建了水工程预报调度与活水自流联控联调平台,提供了多业务应用的“监测预报、动态预警、场景预演、调度预案”4个关键功能,对于推动地方水利设施的精细化管理和智能运维、服务支撑江苏省数字孪生水利建设具有重要参考价值。

Nonlinear Modeling and Identification of Structural Joint by Response Control Vibration Test

Components of mechanical product are assembled by structural joints,such as bolting,riveting,welding,etc.Structural joints introduce nonlinearity to some engineering structures,and the nonlinearity need to be modeled precisely.To meet serious quality requirements,it is necessary to detect and identify nonlinearity of mechanical products for structural optimization.Modal test to acquire a dynamic response has been applied for decades,which provides reliable results for finite element(FE)model updating.Here response control vibration test for identification of nonlinearity is presented.A nonlinear system can be regarded as linearity for particular steady state response,and classical linear analysis tool is applicable to extract modal data for particular response.First,its applicability is illustrated by some numerical simulations.Subsequently,it is implemented on experimental setup with structural joints by shaking table.The stiffness and damping function dependent of relative displacement are fitted to describe its inherent nonlinearity.The spring and damping forces are identified by harmonic balance method(HBM)to predict output response.Based on the identified results,the procedure is recommended that it allows a reliable measurement of nonlinearity with a certain accuracy.

Gas dynamic control of properties of welded joints from high strength alloyed steels

Gas dynamic control in welding with consumable electrode in conditions of two-jet gas shielding and its impact on the processes in the welding area and properties of the welded joints from high strength alloyed steel 30HGSA is considered in the paper. The results of a comparative experimental study of controlling the properties of welded joints by changing the gas dynamics of the active shielding gas are given. The impact force of a shielding gas jet on the drop of the electrode metal is 12 times higher in conditions of two-jet gas shielding than in those of single jet shielding. It is found that gas dynamics of the active shielding gas jet determines the formation of the welded joints, their chemical properties and the properties of the welded joints from high strength alloyed steels. The consumable electrode welding method with two-jet gas shielding provides controlled dynamics in the welding area and allows controlling the transfer of the electrode metal, chemical composition of the weld, stabilizing the welding process, it ensures higher mechanical properties of the welded joints.

Curupira V1.0: Joint Inversion of VES and TEM for Environmental and Mass Movements Studies

An innovative inversion code, named “Curupira v1.0”, has been developed using Matlab to determine the vertical distribution of resistivity beneath the subsoil. The program integrates Vertical Electrical Sounding (VES), successful in shallow subsurface exploration and Time Domain Electromagnetic (TEM) techniques, better suited for deeper exploration, both of which are widely employed in geophysical exploration. These methodologies involve calculating subsurface resistivity through appropriate inversion processes. To address the ill-posed nature of inverse problems in geophysics, a joint inversion scheme combining VES and TEM data has been incorporated into Curupira v1.0. The software has been tested on both synthetic and real-world data, the latter of which was acquired from the Parana sedimentary basin which we summarise here. The results indicate that the joint inversion of VES and TEM techniques offers improved recovery of simulated models and demonstrates significant potential for hydrogeological studies.

钢轨打磨车专用EHA非线性反演控制

为提高钢轨打磨车打磨钢轨的平顺性及稳定性,提出以电动静液作动器(EHA)代替传统液压作动系统作为钢轨打磨车的专用执行器,考虑柱塞泵的总效率波动和液压缸动静摩擦差异大2个非线性因素,建立非线性数学模型;建立EHA的MATLAB、AMESim联合仿真模型,对PID控制、滑模变结构控制、反演控制进行控制策略对比研究,仿真分析验证反演控制在响应快速性及稳定性方面具有良好的表现。搭建四象限平台对EHA进行反演控制负载试验,结果表明:其位移控制精度达0.21 mm,具有较好的控制性能。

基于混合扩张状态观测器的农田平地机液压系统反步滑模控制研究

为解决农田平地机液压系统在复杂地貌平地作业时控制精度低、抗干扰能力差等问题,设计了一种基于混合扩张状态观测器(HESO)的反步滑模控制器。其中,HESO基于输出反馈信号估计系统未知状态和总扰动,并在前馈通道中进行扰动补偿;基于快速趋近律设计的反步滑模控制器输出连续光滑的控制量,增强了系统鲁棒性,克服了系统非线性与参数不确定性问题;通过Lyapunov稳定性理论对所提出的观测器和控制器稳定性进行验证,得到误差一致有界稳定结论;通过AMESim和Matlab/Simulink联合仿真与田间试验对本文控制算法的有效性和优越性进行了验证。在两条地貌情况较为复杂波浪地中单次平地和地貌情况较为相似的两田块进行3次遍历试验表明,使用本文控制方法,平地后高程相较于平地前标高的平均绝对误差、最大绝对误差、绝对误差标准差分别为0.053、0.146、0.037 m和0.02、0.041、0.011 m,较PID算法分别降低36.35%、28.32%、31.37%和62.6%、50%、51.83%。