Optimal Control of Rotation of a Rigid Body by a Movable Internal Mass

Journal of Computer and Systems Sciences International - The two-dimensional problem on the fastest turn of a rigid body by moving an internal mass is considered. It is assumed that the rigid body...     

Objects Changing the Spatial Orientation of a Solid Body by Using Mobile Mass

Journal of Computer and Systems Sciences International - Formulas are obtained that make it possible to realize a predetermined motion of a rigid body with respect to its center of mass in a...     

Abnormal Optimal Trajectory Planning of Multi-Body Systems in the Presence of Holonomic and Nonholonomic Constraints

In optimal control problems, the Hamiltonian function is given by the weighted sum of the integrand of the cost function and the dynamic equation. The coefficient multiplying the integrand of the cost function is either zero or one; and if this coefficient is zero, then the optimal control problem is known as abnormal; otherwise it is normal. This paper provides a characterization of the abnormal optimal control problem for multi-body mechanical systems, subject to external forces and moments, and holonomic and nonholonomic constraints. This study does not only account for first-order necessary conditions, such as Pontryagin’s principle, but also for higher-order conditions, which allow the analysis of singular optimal controls.     

固体质量流量计在密相气力输送中的应用

介绍了Thermo Ramsey公司生产的电容式固体质量流量计在粉煤气力输送过程中的应用情况,探讨了该流量计固有参数设定、管路中安装位置、输送煤粉浓度以及标定方法对其测量精度的影响,对于掌握该流量计的使用方法和性能具有一定指导作用,为气固两相流的基础研究及其工业在线测量提供了有益的参考。     

Implied Scenario Detection in the Presence of Behaviour Constraints

Scenario-based specifications describe how independent components interact to provide system level behaviour. The specified system decomposition and system behaviour can give rise to implied scenarios, which are the result of specifying the global behaviour of a system that will be implemented component-wise. The existence of implied scenarios is an indication that further validation with stakeholders must be done. An implied scenario can be accepted or rejected by stakeholders indicating that the implied scenario is acceptable system behaviour or a situation that should be avoided. In consequence, implied scenarios can be used to iteratively drive requirement elicitation. However, in order to do so, we must be capable of detecting implied scenarios in the presence of rejected implied scenarios, in other words in the presence of behaviour constraints. The contribution of this paper is a technique for detecting implied scenarios in message sequence chart (MSC) specifications that can be used in conjunction with behaviour constraints. The technique is based on building a Coordinator component that forces system components to follow the same sequence of basic MSCs as they go through a high-level MSC. The result is a model that behaves as specified in the MSC but does not comply with the MSC architecture. The resulting model is not a proposed implementation, rather a precise model of specified behaviour that can be used in combination with constrained implementation models to detect further implied scenarios.     

Finite Elements in the Presence of Occasionally Binding Constraints

This paper proposes and compares in terms of speed and accuracy two alternative approximation methods employing finite elements to parameterize the true policy functions that solve for the equilibrium of an optimal growth model with leisure and irreversible investment. The occasionally binding constraint in investment is efficiently handled on one algorithm by parameterizing the expectations of the marginal benefit of future physical capital stock and on the other by modifying the planner’s problem to include a penalty function. While both methods benefit from the high speed and accuracy achieved by a finite elements approximation, the algorithm incorporating a penalty function in the planner’s problem proved being of fastest convergence over a whole range of the model’s calibrations.     

Reorientation of a Rigid Body Controlled by a Movable Internal Mass

Journal of Computer and Systems Sciences International - The problem of controlling the orientation of a rigid body using a movable internal mass is studied. A method for calculating the motion of...     

Quasi-Optimal Braking of Rotations of a Body with a Moving Mass Coupled to It through a Quadratic Friction Damper in a Resisting Medium

This paper addresses the problem of the time-optimal braking of rotations of a dynamically symmetric rigid body under a small control moment in the ellipsoidal range with close unequal values of the ellipsoid’s semiaxes. This problem is considered a problem of quasi-optimal control. The body is assumed to have a moving mass connected to it through elastic coupling with quadratic dissipation. In addition, the body is exposed to a small braking moment of the linear resistance of the medium. The problem of synthesizing the quasi-optimal braking of the rotations of a dynamically symmetric body in a resisting medium is investigated analytically and numerically. An approximate solution is found by the phase-averaging of the processional motion. The qualitative properties of quasi-optimal motion are analyzed and the corresponding graphs are presented.     

Thinking Aloud in the Presence of Interruptions and Time Constraints

Thinking aloud is widely used for usability evaluation, and its reactivity is therefore important to the quality of evaluation results. This study investigates whether thinking aloud (i.e., verbalization at Levels 1 and 2) affects the behavior of users who perform tasks that involve interruptions and time constraints, two frequent elements of real-world activities. The study finds that the presence of auditory, visual, audiovisual, or no interruptions interacts with thinking aloud for task solution rate, task completion time, and participants' fixation rate. Thinking-aloud participants also spend longer responding to interruptions than control participants. Conversely, the absence or presence of time constraints does not interact with thinking aloud, suggesting that time pressure is less likely to make thinking aloud reactive than previously assumed. These results inform practitioners faced with the decision to either restrict verbalizations in usability evaluation to thinking aloud to avoid reactivity or relax the constraints on verbalization to obtain additional information.     

Trajectory Tracking Control of a Quadrotor Aerial Vehicle in the Presence of Input Constraints

International Journal of Control, Automation and Systems - In this paper, we address the control problem of a Quadrotor Aerial Vehicle (QAV) in the presence of the input constraints. For this...     

有环境约束时完成一族跟踪任务的力控制

本文为工业机器人提出了一种极点配置控制法，这种控制方法的优点有：一是它的积分作用消除了机器人的微小扰动和稳态误差；二是能任意设置系统的极点，因此能保证闭环系统的稳定性和规定状态变量的暂态响应；三是加入了加速度反馈，抑制了由电枢电感所引起的机械手的振动，最后，给出了ＰＵＭＡ５６２机器人的计算机仿真和实验结果验证了此控制法的有效性。     

运行体的水波生成与扩散模拟算法

根据数字图像处理的基本原理,采用邻域扩散的思想,结合水波的物理意义,提出了一种综合线性叠加和线性滤波的运动体在水域中形成的运行水波的生成与扩散数值模拟算法.首先,讨论了在无外力影响的情况下,波源加入的算法模型,并给出了几个振荡发生器及其快速实现方法.然后,对水波扩散与衰减给出了八邻域滤波和二十四邻域滤波实现的模拟方法.接着,对实现水波立体感的方法进行了分析,给出了水波折射效果及其表达方法的算法模型.最后给出了通过本文算法进行模拟实验的效果对比图.该算法准确度较高,速度快,效果较好,对虚拟现实的实现具有较大的实用价值.     

Optimal Representative Blocks for the Efficient Tracking of a Moving Object

Optimal representative blocks are proposed for an efficient tracking of a moving object and it is verified experimentally by using a mobile robot with a pan‐tilt camera. The key idea comes from the fact that when the image size of a moving object is shrunk in an image frame according to the distance between the camera of mobile robot and the moving object, the tracking performance of a moving object can be improved by shrinking the size of representative blocks according to the object image size. Motion estimation using edge detection (ED) and block‐matching algorithm (BMA) are often used in the case of moving object tracking by vision sensors. However, these methods often miss the real‐time vision data since these schemes suffer from the heavy computational load. To overcome this problem and to improve the tracking performance, the optimal representative block that can reduce a lot of data to be computed is defined and optimized by changing the size of the representative block according to the size of object in the image frame. The proposed algorithm is verified experimentally by using a mobile robot with a two degree‐of‐freedom active camera. © 2004 Wiley Periodicals, Inc.     

Stabilization Methods for the Integration of DAE in the Presence of Redundant Constraints

The use of multibody formulations based on Cartesian or naturalcoordinates lead to sets of differential-algebraic equations that haveto be solved. The difficulty in providing compatible initial positionsand velocities for a general spatial multibody model and the finiteprecision of such data result in initial errors that must be correctedduring the forward dynamic solution of the system equations of motion.As the position and velocity constraint equations are not explicitlyinvolved in the solution procedure, any integration error leads to theviolation of these equations in the long run. Another problem that isvery often impossible to avoid is the presence of redundant constraints.Even with no initial redundancy it is possible for some systems toachieve singular configurations in which kinematic constraints becometemporarily redundant. In this work several procedures to stabilize thesolution of the equations of motion and to handle redundant constraintsare revisited. The Baumgarte stabilization, augmented Lagrangian andcoordinate partitioning methods are discussed in terms of theirefficiency and computational costs. The LU factorization with fullpivoting of the Jacobian matrix directs the choice of the set ofindependent coordinates, required by the coordinate partitioning method.Even when no particular stabilization method is used, a Newton–Raphsoniterative procedure is still required in the initial time step tocorrect the initial positions and velocities, thus requiring theselection of the independent coordinates. However, this initialselection does not guarantee that during the motion of the system otherconstraints do not become redundant. Two procedures based on the singlevalue decomposition and Gram–Schmidt orthogonalization are revisited forthe purpose. The advantages and drawbacks of the different procedures,used separately or in conjunction with each other and theircomputational costs are finally discussed.     

一类受限线性系统的最优控制

研究了一类受限线性系统的最优控制问题.对于输入和状态联合受限线性系统的最优控制,引入多参数二次规划方法进行求解;首先将控制问题转化为标准的多参数二次规划问题,然后应用多参数二次规划方法求得系统的可行状态空间及其子空间,并对每个子空间的求出其时变最优控制率,最后归纳上述过程得到一般性结论.方法不仅能使系统约束的处理更加系统化和透明化,还可以获得系统的显式分段仿射控制率.仿真结果表明了该方法的有效性.     

无线传感器网络覆盖问题中的目标最优运动模式

研究无线传感器网络中的覆盖问题,这对传感器网络的节能、性能优化以及部署策略等问题具有十分重要的意义．相对已有的传感器模型和Exposure模型,给出更合理、更符合实际的模型．而且新模型便于分析计算．给定目标的起点,分析出使其具有最大值和最小Exposure值的运动方向;给定目标的速率和运行时间,分析出使其Exposure值最大的运动模式．对Exposure的分析简化了对覆盖问题的分析工作．仿真结果验证了理论分析的正确性．     

Time Quasi-Optimal Deceleration of Rotations of a Gyrostat with a Moving Mass in a Resistive Medium

Journal of Computer and Systems Sciences International - The problem of time quasi-optimal deceleration of the rotations of a rigid body that includes elements with distributed and lumped...     

Use of Principal Axes as the Floating Reference Frame for a Moving Deformable Body

In this paper a method to adopt the principal axes of a deformable body as its body-attached frame is presented. The deformable body in a multibody setting is allowed to deform while it undergoes rigid-body motion. The fundamental concepts of imposing the principal axes as a moving reference frame are that the origin of the frame must remain at the instantaneous mass center and that the three products of inertia must remain zero as the body deforms. These conditions require the construction of several auxiliary matrices that are used in the constraint equations at the position, velocity, and acceleration levels. These auxiliary matrices are constructed only once and remain unchanged through the motion of the deformable body. The presented formulation does not depend on the type of finite element and multibody formulations or any associated assumptions.     

Optimal Control of the Dynamic Viscoelastic Stress-Strain State of a Composite Body

New optimal control problems for the dynamic viscoelastic stress-strain state of a composite body with quadratic cost functionals are considered. Existence theorems for unique optimal controls are proved for all the cases considered. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 5, pp. 73–92, September–October 2005.     

移动质心自旋再入飞行器的建模与解耦控制

对移动质心控制自旋再入飞行器进行了概念研究.以所建立的移动质心自旋再入飞行器的姿态动力学模型为基础,分析其控制耦合特性,借鉴工程中易于实现的逆奈奎斯特阵列法,对被控对象进行预补偿,使其传递函数矩阵成为具有对角优势来削弱被控对象各回路间的耦合,然后再运用单变量系统的频域设计方法对每个回路单独设计,从而将复杂的多变量设计问题转化为单变量设计问题,解决较强耦合下自旋再入飞行器姿态稳定性同题.仿真分析表明,对被控对象进行预补偿设计后,系统达到了较好的解耦效果.