{"title":"动力系统","authors":"D. Nychka","doi":"10.4135/9781446247501.n1150","DOIUrl":null,"url":null,"abstract":"Many engineering and natural systems are dynamical systems. For example a pendulum is a dynamical system. l mg 2 Figure 1. Simple pendulum. State The state of the dynamical system specifies it conditions. For a pendulum in the absence of external excitation shown in the figure, the angle and the angular velocity uniquely define the state of the dynamical system. Plots of the state variables against one another are referred to as the phase space representation. Every point in the phase space identifies a unique state of the system. For the pendulum, a plot of θ versus & θ is the phase space representation. The equation of motion of a dynamical system is given by a set of differential equations. That is) f(x x t , = & (1) where x is the state and t is time. The dynamical system is linear if the governing equation is linear. For the pendulum shown in Figure 1, the equation of motion is given as ⎩ ⎨ ⎧ θ ω − ω ζω − = ω ω = θ sin 2 2 o o & & where l g 2 o = ω (2) and the dynamical system is nonlinear. For small amplitude oscillation, and the equation of motion becomes , sin θ ≈ θ ⎩ ⎨ ⎧ θ ω − ω ζω − = ω ω = θ 2 o o 2 & & (3) The dynamical system is now linear. In Equations (2) and (3) o ω is the natural frequency and ζ is the damping coefficient. A system is said to autonomous if time does not appear explicitly in the equation of motion. The equation of motion of nonautonomous systems, however, explicitly","PeriodicalId":331638,"journal":{"name":"Control Theory for Physicists","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Dynamical Systems\",\"authors\":\"D. Nychka\",\"doi\":\"10.4135/9781446247501.n1150\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Many engineering and natural systems are dynamical systems. For example a pendulum is a dynamical system. l mg 2 Figure 1. Simple pendulum. State The state of the dynamical system specifies it conditions. For a pendulum in the absence of external excitation shown in the figure, the angle and the angular velocity uniquely define the state of the dynamical system. Plots of the state variables against one another are referred to as the phase space representation. Every point in the phase space identifies a unique state of the system. For the pendulum, a plot of θ versus & θ is the phase space representation. The equation of motion of a dynamical system is given by a set of differential equations. That is) f(x x t , = & (1) where x is the state and t is time. The dynamical system is linear if the governing equation is linear. For the pendulum shown in Figure 1, the equation of motion is given as ⎩ ⎨ ⎧ θ ω − ω ζω − = ω ω = θ sin 2 2 o o & & where l g 2 o = ω (2) and the dynamical system is nonlinear. For small amplitude oscillation, and the equation of motion becomes , sin θ ≈ θ ⎩ ⎨ ⎧ θ ω − ω ζω − = ω ω = θ 2 o o 2 & & (3) The dynamical system is now linear. In Equations (2) and (3) o ω is the natural frequency and ζ is the damping coefficient. A system is said to autonomous if time does not appear explicitly in the equation of motion. The equation of motion of nonautonomous systems, however, explicitly\",\"PeriodicalId\":331638,\"journal\":{\"name\":\"Control Theory for Physicists\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"1900-01-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Control Theory for Physicists\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.4135/9781446247501.n1150\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Control Theory for Physicists","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.4135/9781446247501.n1150","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
摘要
许多工程系统和自然系统都是动力系统。例如,钟摆就是一个动力系统。1 mg 2图1单摆。状态动力系统的状态规定了它的条件。对于图中所示的没有外部激励的摆,角度和角速度唯一地定义了动力系统的状态。状态变量相互对应的图称为相空间表示。相空间中的每个点都表示系统的唯一状态。对于摆,θ与& θ的关系图是相空间的表示。动力系统的运动方程由一组微分方程给出。即f(x x t) = &(1)其中x是状态,t是时间。如果控制方程是线性的,那么动力系统就是线性的。对于图1所示的钟摆,其运动方程为: θ ω−ω ζω−= ω ω = θ sin 22 o o & &其中l g 20 o = ω(2),动力系统为非线性。对于小振幅振荡,运动方程变为,sin θ≈θ ω - ω ζω−= ω ω = θ 2 o 2 & &(3)此时动力系统是线性的。在式(2)和(3)中,0 ω是固有频率,ζ是阻尼系数。如果时间不显式地出现在运动方程中,我们就说一个系统是自治的。然而,非自治系统的运动方程是明确的
Many engineering and natural systems are dynamical systems. For example a pendulum is a dynamical system. l mg 2 Figure 1. Simple pendulum. State The state of the dynamical system specifies it conditions. For a pendulum in the absence of external excitation shown in the figure, the angle and the angular velocity uniquely define the state of the dynamical system. Plots of the state variables against one another are referred to as the phase space representation. Every point in the phase space identifies a unique state of the system. For the pendulum, a plot of θ versus & θ is the phase space representation. The equation of motion of a dynamical system is given by a set of differential equations. That is) f(x x t , = & (1) where x is the state and t is time. The dynamical system is linear if the governing equation is linear. For the pendulum shown in Figure 1, the equation of motion is given as ⎩ ⎨ ⎧ θ ω − ω ζω − = ω ω = θ sin 2 2 o o & & where l g 2 o = ω (2) and the dynamical system is nonlinear. For small amplitude oscillation, and the equation of motion becomes , sin θ ≈ θ ⎩ ⎨ ⎧ θ ω − ω ζω − = ω ω = θ 2 o o 2 & & (3) The dynamical system is now linear. In Equations (2) and (3) o ω is the natural frequency and ζ is the damping coefficient. A system is said to autonomous if time does not appear explicitly in the equation of motion. The equation of motion of nonautonomous systems, however, explicitly