自控原理+答案

宝鸡文理学院试题

课程名称 自动控制原理 适 用 时 间 大二第二学期 试卷类别 一 适 用 专 业 自动化

一、填空(每空2分，共20分)

The word control is usually taken to mean (1).Control theory itself has two categories，they are (2).By definition，the (3) of a component or system is the ratio of the transformed output to the transformed input .In time domain，the three basic performance criteria for a control system are (4) and (5).The (6) criterion is a method for determining continuous system stability. The (7) technique is a graphical method of determining the location of the roots of the characteristic equation as any single parameter，such as (8)，is varied from zero to infinity. In Bode plot , the magnitude M in dB，is plotted against frequency on (9) paper. The software tool of the control system you have known is (10).

二、(10分)已知某系统结构图如下，求其闭环传递函数C（S）/R（S）。

三、(15分)已知单位反馈系统，开环传函为G（S）=K/[S（TS+1）]，要求单位阶跃函数作用时，超调量为16%，调节时间为7，求K，T。

四、(15分)已知单位反馈系统，开环传函为G（S）=k(S+1)/[S(S+1/2)2]，试绘制k从零趋近于无穷大时的根轨迹。

五、(20分)已知最小相位系统开环频率特性的伯德图，要求满足图中的穿越频率wc且不改变原系统的稳态精度。（1）判断采用何种形式的串联校正。（2）画出校正后的对数渐近幅频特性曲线。（3）画出校正环节的对数渐进幅频特性曲线。（4） 小结用频率法进行超前校正的主要步骤。

六、(10分)已知线性元件的频率特性及非线性元件描述函数有关的曲线，两者串联起来构成一单位反馈系统图示，判断系统是否存在自振。

七、 (10分)某离散系统的闭环脉冲传递函数为G（z）=(3.68z+2.64)/(z2+2.31z+3),判断该系统的稳定性。

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宝鸡文理学院试题

课程名称 自动控制原理 适 用 时 间 大二第二学期 试卷类别 一 适 用 专 业 自动化

113

宝鸡文理学院试题

课程名称 自动控制原理 适 用 时 间 大二第二学期 试卷类别 二 适 用 专 业 自动化

1. （本题共15分，第1题8分，第2题7分）

(1) Given a system as following diag., input--- X(s)，output---Y(s).how many forward paths and how many feedback loops are there in the block diagram。

+1/sK 1S?1 + ++ X(s)Y(s) -+ + +1/sK2S?1

(2) solve the transfer function C(z)/R(z) in following diag. system. r(t)c(t)G(s)H2(s)H1(s)2．（本题共15分）Given a system as diag.(a),its unit step response is shown in diag. (b)，solve

K1 、3．（本题共15分）Given a unit feedback system , its open-loop transfer function is

K2 and a。

114

宝鸡文理学院试题

课程名称 自动控制原理 适 用 时 间 大二第二学期 试卷类别 二 适 用 专 业 自动化

prove : its part root locus is a circle when k is 0 to infinity. 4. （本题共15分，第1题8分，第2题7分）

(1) some system, its open loop transfer function isG(s)H(s)?stability using frequency domain method.

(2) when system open loop transfer function is G(s)H(s)?K(T1s?1)(T2s?1),K,T1,T2>0,illustrate closed loop

10(5s?1)(10s?1),check closed loop system

system stability using Nyquist criterion. （15%） 5. （本题共20分，第1、2题各6分，第3题8分）three minimum phase systemⅠ、Ⅱ、Ⅲ,their open-loop bode diag. is as following

(1) compare their ts,б% when the input is a unit step; (2) compare their ess when the input is a unit ramp；

(3) compare phase margin and amplitude margin of systemⅠ、Ⅱ。 6. （本题共15分）A non-linear control system with saturation is shown as following dia. the description function

of saturation non-linearity is N（A）?system stable, solve K1.

7．（本题共5分，第Given a system, its closed-loop transfer function is Gb(s)?s?2s?3s?4442322k?[arcsinaA?aA1?(aA)]2(A?a) .in order to make the

5s?6s?7s?8s?9some MATLAB command to solve its unit step response and unit impulse response.

, write

115

宝鸡文理学院试题

课程名称 自动控制原理 适 用 时 间 大二第二学期 试卷类别 三 适 用 专 业 自动化

1 （本题共30分，每题3分）select the appropriate answer to the following questions: 1.1 a unit feedback system, its open transfer function is G(s)?steady-state error is（）.

（1）0 （2）∞ （3）0.01 （4）100 1.2 a series correction transfer function is Gc(s)?s?10.1s?110000(s?1)(5s?1)s(s?4s?100)22，when the input is

t22,its

,it is a kind of ( )

（1）lag correction （2）lead correction （3）lag－lead correction (4) proportion correction 1.3 if we express 0.001 in dB, its value is ( ) dB.

（1）3 （2）－3 （3）－60 （4）60

100(0.1s?1)(0.01s?1)1.4 a system’s transfer function is G(s)?,its poles are(is)（ ）

(s?1)(0.001s?1)（1）10，100 （2）－1，－1000 (3) 1， 1000 （4）－10， －100 1.5 a system’s transfer function is G(s)?110s?1,the value of its unit pulse response is ( ) when t=0.

（1）0 （2）∞ （3）0.1 （4）1

1.6 a second-order system’s damped ratio is 2，its step response is（ ） (1) oscillation divergent （2）monotonous attenuating

（3）oscillation attenuating （4）constant amplitude oscillation 1.7 the larger the cut-off frequency,（ ）

(1) the better the anti-disturbance capacity to high frequency signal. (2) the shorter its transient response time. (3) The worse its response speed. (4) the smaller its steady-state error.

1.8 in order to improve second-order system stability, we can（）

（1）increase ?n （2）decrease ?n（3）increase ? （4）decrease ?

1.9 the stability depends on a system’s（） （1）disturbance.

（2）the acting point of the disturbance. （3）poles’ position. （4）input.

1.10 according to the given phase margin, we know system ( ) has the best stability.

（1）?1?70? （2）?2??50?（3）?3?0? （4）?4?30?

2 （本题共10分，每题各5分）(1) Given a system as following figure 1, Solve its closed-loop transfer function。

figure1 figure 2 c(t)r(t) G(s) H2(s)H1(s)

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