Solving position-posture deviation problem of multi-legged walking robots with semi-round rigid feet by closed-loop control

The semi-round rigid feet would cause position-posture deviation problem because the actual foothold position is hardly known due to the rolling effect of the semi-round rigid feet during the robot walking. The position-posture deviation problem may harm to the stability and the harmony of the robot, or even makes the robot tip over and fail to walk forward. Focused on the position-posture deviation problem of multi-legged walking robots with semi-round rigid feet, a new method of position-posture closed-loop control is proposed to solve the position-posture deviation problem caused by semi-round rigid feet, based on the inverse velocity kinematics of the multi-legged walking robots. The position-posture closed-loop control is divided into two parts: the position closed-loop control and the posture closed-loop control. Thus, the position-posture control for the robot which is a tight coupling and nonlinear system is decoupled. Co-simulations of position-posture open-loop control and position-posture closed-loop control by MATLAB and ADAMS are implemented, respectively. The co-simulation results verify that the position-posture closed-loop control performs well in solving the position-posture deviation problem caused by semi-round rigid feet.

Optimal control of attitude for coupled-rigid-body spacecraft via Chebyshev-Gauss pseudospectral method

The attitude optimal control problem （OCP） of a two-rigid-body space- craft with two rigid bodies coupled by a ball-in-socket joint is considered. Based on conservation of angular momentum of the system without the external torque, a dynamic equation of three-dimensional attitude motion of the system is formulated. The attitude motion planning problem of the coupled-rigid-body spacecraft can be converted to a dis- crete nonlinear programming （NLP） problem using the Chebyshev-Gauss pseudospectral method （CGPM）. Solutions of the NLP problem can be obtained using the sequential quadratic programming （SQP） algorithm. Since the collocation points of the CGPM are Chebyshev-Gauss （CG） points, the integration of cost function can be approximated by the Clenshaw-Curtis quadrature, and the corresponding quadrature weights can be calculated efficiently using the fast Fourier transform （FFT）. To improve computational efficiency and numerical stability, the barycentric Lagrange interpolation is presented to substitute for the classic Lagrange interpolation in the approximation of state and con- trol variables. Furthermore, numerical float errors of the state differential matrix and barycentric weights can be alleviated using trigonometric identity especially when the number of CG points is large. A simple yet efficient method is used to avoid sensitivity to the initial values for the SQP algorithm using a layered optimization strategy from a feasible solution to an optimal solution. Effectiveness of the proposed algorithm is perfect for attitude motion planning of a two-rigid-body spacecraft coupled by a ball-in-socket joint through numerical simulation.

Attitude Control of an Axi-Symmetric Rigid Body Using Two Controls without Angular Velocity Measurements Paper

This paper considers the problem of controlling the rotational motion of an axi-symmetric rigid body using two independent control torques without angular velocity measurements. The control law which stabilizes asymptotically this motion is obtained only in terms of the orientation parameters. Global asymptotic stability is shown by applying LaSalle invariance principal. Numerical simulation is introduced.

Analysis on influence of seismic travelling wave effect on semi-active control for long-span rigid-continuous bridge

The analysis approach of semi-active control for long-span rigid-continuous bridge under seismic travelling wave input is established. Magnetorheological dampers are set on the positions of the bridge beatings. The semi-active control calculation and analysis are performed for a five-span rigid-continuous bridge under seismic travelling waves with different apparent surface velocities. The results indicate that travelling wave effect remarkably influences the uncontrolled seismic responses, the semi-active control seismic responses and vibration control effects for the long-span rigid-continuous bridge. It is disadvantageous to the responses of the beams and the piers under the travelling wave input with lower apparent surface velocity, and travelling wave effect can decrease the vibration control effects evidently. Therefore, the travelling wave effect should be considered for the selection of the parameter values of semi-active control system in order to get the designing control effect.

Terminal sliding mode control for coordinated motion of a space rigid manipulator with external disturbance

The control problem of coordinated motion of a free-floating space rigid manipulator with external disturbance is discussed. By combining linear momentum conversion and the Lagrangian approach, the full-control dynamic equation and the Jacobian relation of a free-floating space rigid manipulator are established and then inverted to the state equation for control design. Based on the terminal sliding mode control （SMC） technique, a mathematical expression of the terminal sliding surface is proposed. The terminal SMC scheme is then developed for coordinated motion between the base＇s attitude and the end-effector of the free-floating space manipulator with external disturbance. This proposed control scheme not only guarantees the existence of the sliding phase of the closed-loop system, but also ensures that the output tracking error converges to zero in finite time. In addition, because the initial system state is always at the terminal sliding surface, the control scheme can eliminate reaching phase of the SMC and guarantee global robustness and stability of the closed-loop system. A planar free-floating space rigid manipulator is simulated to verify the feasibility of the proposed control scheme.

An Overview of Research in Distributed Attitude Coordination Control

This paper provides an overview of attitude coordination problems of multi-rigid-body with the goal of promoting research in this area. Theoretical results regarding consensus seeking with different system models, different communication topologies, different control goals and different techniques are summarized. And applications of consensus protocols to multirigid- body coordination are investigated. Finally, some future research directions and open problems are also proposed. © 2014 Chinese Association of Automation.

Dynamic Modeling and Adaptive Fast Nonsingular Terminal Sliding Mode Control for Satellite with Double Rotary Payloads

A robust attitude control methodology is proposed for satellite system with double rotary payloads. The dynamic model is built by the Newton-Euler method and then the dynamic interconneetion between satellite＇s main body and payloads is described precisely. A nonlinear disturbance observer is designed for satellite＇s main body to estimate disturbance torque acted by motion of payloads. Meanwhile, the adaptive fast nonsingular terminal sliding-mode attitude stabilization controller is proposed for satellite＇s main body to quicken convergence speed of state variables. Similarly, the adaptive fast nonsingular terminal sliding-mode attitude maneuver controller is designed for each payload to weaken the disturbance effect of motion of satellite＇s main body. Simulation results verify the effectiveness of the proposed method.

Rigidity based formation tracking for multi-agent networks

This paper considers the formation tracking problem under a rigidity framework, where the target formation is specified as a minimally and infinitesimally rigid formation and the desired velocity of the group is available to only a subset of the agents. The following two cases are considered： the desired velocity is constant, and the desired velocity is timevarying. In the first case, a distributed linear estimator is constructed for each agent to estimate the desired velocity. The velocity estimation and a formation acquisition term are employed to design the control inputs for the agents, where the rigidity matrix plays a central role. In the second case, a distributed non-smooth estimator is constructed to estimate the time-varying velocity, which is shown to converge in a finite time. Theoretical analysis shows that the formation tracking problem can be solved under the proposed control algorithms and estimators. Simulation results are also provided to show the validity of the derived results.

A Numerical-analytic Method for Quickly Predicting Springback of Numerical Control Bending of Thin-walled Tube

Springback is one of important factors influencing the forming quality of numerical control （NC） bending of thin-walled tube. In this paper, a numerical-analytic method for springback angle prediction of the process was put forward. The method is based on springback angle model derived using analytic method and simulation results from three-dimensional （3D） rigid-plastic finite element method （FEM）. The method is validated through comparison with experimental results. The features of the method are as follows： （1） The method is high in efficiency because it combines advantages of rigid-plastic FEM and analytic method. （2） The method is satisfactory in accuracy, since the field variables used in the model is resulting from 3D rigid-plastic FEM solution, and the effects both of axial force and strain neutral axis shift have been included. （3） Research on multi-factor effects can be carried out using the method due to its advantage inheriting from rigid-plastic FEM. The method described here is also of general significance to other bending processes.

刚性联接双电机系统功率平衡控制策略

针对刚性联接双电机系统因参数摄动和负载变化导致的系统输出功率不均衡问题,基于转矩闭环矢量控制系统,提出了一种自抗扰模型预测(ADRC-MPCC)转矩交叉耦合功率平衡控制策略。首先,建立刚性联接双电机系统的统一数学模型,基于该模型分析了功率不平衡产生的原因;其次,通过确定合适的转矩反馈补偿系数,提高了系统中双电机的同步性能;最后,设计自抗扰控制器对转速环、磁链环和转矩环的扰动进行估计和补偿,并通过简化模型预测控制方法对逆变器开关状态进行选择,减少了控制器的运算时间。仿真与实验结果表明,提出的控制策略实现了参数摄动和负载扰动情况下刚性联接双电机系统的输出功率平衡,验证了功率平衡控制策略的有效性。

运载火箭姿态控制速率陀螺自适应加权方法

针对运载火箭反馈控制回路中弹性振动信号与刚体信号存在耦合,会明显降低姿控系统稳定性的问题,提出了一种速率陀螺自适应加权方法,该方法适用于弹性振动的模态振型斜率和频率存在偏差的情况。将速率陀螺观测信号转换为频域表达,采用插值离散傅里叶变换方法辨识弹性频率;基于频域信号提出了速率陀螺加权系数矩阵自适应更新算法,分步抑制了各阶弹性振动信号;开展了不同偏差情况下的仿真校验工作。仿真结果表明,速率陀螺自适应加权方法可实现对速率陀螺测量信号中弹性振动信号的显著抑制,从源头上减小弹性振动信号对姿控系统稳定性的不利影响,从而提高运载火箭姿态控制器的性能,降低控制器的设计难度。

基于对偶四元数的多体系统动力学建模和控制

空间机械臂的在轨作业是当前空间在轨服务中应用最为广泛的技术之一,然而,机械臂在操作过程中漂浮基座与臂体之间的位姿耦合效应极为显著,这给控制系统设计带来了新挑战.针对多刚体系统的位姿一体化建模与控制问题,文章改进了基于对偶四元数的位姿一体化建模和控制方法,使之可以应用于多刚体系统.该方法不仅能够精确描述复杂的力学关系,还能够在统一的数学框架中有效地处理位姿耦合问题,这为后续设计姿轨一体化的控制系统提供了极大的便利.首先,基于铰链模型建立了对偶四元数形式的铰链和臂体之间的速度和加速度递推关系,然后,利用铰链和臂体间力-力矩传递关系建立了递推形式的逆向动力学方程,为了便于控制系统设计与分析,随后推导建立了矩阵形式的位姿一体化的正向动力学方程.然后针对推进器和控制力矩陀螺讨论了具体的执行机构的动力学建模问题,并分别讨论了机械臂和漂浮基座的位姿一体化控制问题.最后,对一个6自由度机械臂和漂浮基座的组合体进行了动力学建模和控制仿真,动力学仿真的结果证明了所提动力学建模方法的正确性,控制仿真表明控制系统能较快地抵消机械臂运动对基座产生的干扰力和干扰力矩,证明了所提控制方法的有效性和可行性.

基于机电液联合仿真的高空测试转台俯仰运动控制

针对高空测试转台俯仰运动存在负载不平衡以及液压缸之间的耦合效应,通过Adams和AMESim分别构建高空测试转台三维俯仰转台的刚柔耦合动力学模型和电液控制系统模型,采用PID控制算法对测试转台俯仰系统技术指标要求的工况进行联合仿真。结果表明:俯仰平台的实际角度能很好地跟踪角度指令,满足定向精度要求,为后续的试验研究奠定了理论基础。该方法弥补了单一仿真软件不能对系统进行完整仿真的不足,可以更加全面、准确地反映研究对象的真实控制与运动状态,对于复杂的机电液一体化系统具有普遍的适用性。

两栖装甲车水上运动仿真平台开发与应用研究

为设计及验证两栖装甲突击车大风浪条件下的火控算法,需要开发其实时仿真平台。传统单刚体车辆动力学模型无法反映车体-炮塔-炮管间复杂的动力学耦合关系,不适合于高动态特性的火控仿真。使用twist-wrench方法建立了车辆的多刚体动力学模型,根据车体与视景中生成的海浪之间的运动关系计算浮力和水动力,水动力系数则事先通过计算流体力学方法得出。以一种滑模控制器为例验证了此系统作为火控算法开发及验证平台的有效性。

复杂地形下轮腿复合机动平台动态运动控制

复杂地形环境下质心参考轨迹的动态精确跟踪是保障轮腿复合机动平台稳定执行各项任务的关键。为提升平台的地形适应能力与位姿跟踪能力,提出一种动态运动控制策略。综合地形因素,建立包含车轮动力学的单刚体动力学模型,并通过近似简化将系统动力学模型转化为状态空间方程的标准形式。考虑车轮与腿部耦合运动,提出一种基于前馈力矩与反馈力矩的混合运动控制方法。通过二次规划算法求解最优地面反作用力,利用雅克比矩阵将作用力映射至关节以获取前馈力矩。为避免由环境引起的外部扰动造成系统无法在较短时间内完成优化计算,引入关节力矩反馈控制及时修正位姿跟踪误差,使系统能够快速准确地响应外部扰动,有效提高系统的鲁棒性和稳定性。仿真结果表明,新方法可有效提升平台在复杂地形下位姿动态跟踪精度,保障平台平稳运行,为复杂地形下轮腿复合机动平台的工程应用提供有力支撑。

倾转旋翼无人机过渡段控制策略研究

针对倾转旋翼无人机过渡段的纵向控制问题,以某型倾转旋翼无人机为研究对象,综述了国内倾转旋翼机的发展趋势。利用Rotorlib软件建立倾转旋翼无人机的6自由度刚体模型;通过频域和时域对过渡段的特性进行分析,设计出过渡段的舵面操纵分配策略;对总距控制通道的控制结构进行设计。由于倾转旋翼在过渡过程中总距控制通道存在严重的耦合,根据动力学方程分析提出余弦分配的策略来改进耦合问题。通过仿真验证了余弦分配对于总距控制通道的耦合问题有明显的改善。

基础筏板刚性防水施工关键技术及质量控制研究

以宁海路某工程基础筏板刚性防水施工为例,介绍了逆作法深基坑基础筏板刚性防水施工关键部位施工缝、抗拔桩桩头、地下连续墙与筏板交接处的质量防范措施,以及施工中遇到的基岩裂隙水处理方法。结果表明,采用刚性防水方式有效缩短了工期,同时确保了防水工程的质量,为类似工程提供了丰富的经验和指导,有望对建筑工程领域产生积极的影响。

基于刚体模型的光电伺服系统最优控制方法

在现阶段的导弹武器系统中,控制系统大都采用经典PID控制器,但随着控制性能要求的不断提升,PID控制器在追求响应快速的同时难以兼得跟踪过程平稳;针对工程中遇到的以上问题,提出设计最优控制器,采用线性二次型调节器(LQR)求解最优控制律;通过仿真可以看到,最优控制器跟踪阶跃信号无静差,调节时间为0.034 s,上升过程平稳无超调;跟踪斜坡信号和正弦信号时,跟踪误差远小于,滞后时长仅为毫秒量级;最优控制器系统能够实现快速跟踪阶跃、斜坡和正弦输入信号,且具有较好的跟踪性能;与经典PID控制器相比,该方法具有更高的控制精度、更好的控制性能和稳定性,能够解决PID控制器在工程中遇到的快速性和平稳性难以兼得的难题。

超长地下室刚性自防水混凝土结构设计

对于超长地下室刚性自防水设计,混凝土结构设计是防水设计工作年限不低于主体结构设计工作年限的关键。本文结合武汉市某新建刚性自防水超长地下室项目,介绍了一系列实现超长地下室刚性自防水设计的结构设计措施,采用三维有限元分析软件YJK对超长地下室温度应力进行分析,同时提出了一种配置温度钢筋以控制混凝土楼板温度裂缝的结构设计方法,可为类似工程的设计提供参考。

持续质量改进管理在硬式内镜器械清洗消毒质量控制中的应用效果分析

目的:探讨持续质量改进(CQI)管理在硬式内镜器械清洗消毒质量控制中的应用效果。方法:选取2022年1—6月徐州市肿瘤医院消毒供应中心的230件硬式内镜器械作为对照组,选取2022年7—12月消毒供应中心的230件硬式内镜器械作为研究组。对照组应用常规管理模式,研究组应用CQI管理模式。比较两组消毒灭菌质量及工作人员工作压力、满意度。结果:研究组回收质量、分类质量、清洗质量、消毒质量、干燥质量、包装质量、灭菌质量、存储质量、发放质量评分高于对照组,差异有统计学意义(P<0.001)。研究组工作压力评分低于对照组,工作满意度各项评分高于对照组,差异有统计学意义(P<0.001)。结论:CQI管理模式在硬式内镜器械清洗消毒质量控制中的应用效果良好,能够提高硬式内镜器械清洗消毒质量,减轻消毒供应中心工作人员工作压力,提高其工作满意度。