磁盘驱动读取系统的分析设计.doc

磁盘驱动读取系统的分析设计一、闭环系统的性能分析（1）确定使闭环系统稳定的Ka的取值范围 G1=tf(5000,1,1000); G2=tf(1,conv(1,0,1,20); G=series(G1,G2) Transfer function: 5000-s3 + 1020 s2 + 20000 sg3= 一一开环传函G3= 一一闭环传函 syms K den den=1 1020 20000 5000*K; K=den(2)*den(3)/den(1)/5000 K = 4080有劳斯判据可得k的范围是0 K g=100*Gg1=feedback(g,1)C=dcgain(g1) Transfer function: 500000-s3 + 1020 s2 + 20000 s Transfer function: 500000-s3 + 1020 s2 + 20000 s + 500000 C = 1c,t=step(g1); y,k=max(c); percentovershoot=100*(y-C)/Cpercentovershoot = 21.6918调节时间函数t=setllingtime(g1)t = 0.3697K=1000时 g=1000*GTransfer function: 5e006-s3 + 1020 s2 + 20000 s g2=feedback(g,1)Transfer function: 5e006-s3 + 1020 s2 + 20000 s + 5e006 c,t=step(g2); C=dcgain(g2)C = 1 y,k=max(c)y = 1.7109k = 11 percentovershoot=100*(y-C)/Cpercentovershoot = 71.0891t=setllingtime(g2)t = 0.4989超调量 调节时间0.3697(s)K=1000时超调量 调节时间0.4989 (s)（3）考察扰动信号为单位阶跃时，上述两个Ka取值情况下，系统的抗干扰能力，并进行分析 g2=tf(1,conv(1 0,1 20) Transfer function: 1-s2 + 20 s g1=tf(5000,1 1000) Transfer function: 5000-s + 1000 syms k g3=feedback(g2,g1,1) Transfer function: s + 1000-s3 + 1020 s2 + 20000 s - 5000 g3=feedback(g2,-g1,1) Transfer function: s + 1000-s3 + 1020 s2 + 20000 s + 5000 g4=-g3 Transfer function: -s - 1000-s3 + 1020 s2 + 20000 s + 5000 -扰动输入的传递函数当K=100时 g=tf(-1 -1000,1 1020 20000 500000)Transfer function: -s - 1000-s3 + 1020 s2 + 20000 s + 500000 c,t=step(g); y,k=min(c)y = -0.0024k = 15c（t）= 2.4*10-3（s）当K=1000时 g=tf(-1 -1000,1 1020 20000 5000000) Transfer function: -s - 1000-s3 + 1020 s2 + 20000 s + 5e006 c,t=step(g); y,k=min(c)y = -3.4308e-004k = 11c（t）= 0.34*10-3（s）(4)针对如下的性能指标要求，折中选取一个合适的Ka值取Ka=100二、速度反馈系统的性能分析（1）运用第3章中所学的劳斯判据，确定要使闭环系统稳定，Ka和K1应如何选取？Ka=100，K1=0.03（2）针对你选取的Ka和K1，仿真闭环系统的阶跃响应，并计算超调量、调节时间和对单位阶跃扰动的最大响应值。 g1=tf(5000,1 1000) Transfer function: 5000-s + 1000 g2=tf(1,1 20) Transfer function: 1-s + 20 g3=tf(1,1 20) Transfer function: 1-s + 20 g0=feedback(g3*feedback(100*g1*g2,0.03,-1),1) Transfer function: 500000-s3 + 1020 s2 + 35000 s + 500000 t=setllingtime(g0)t = 0.2300 c,t=step(g0); C=dcgain(g0)C = 1 y,k=max(c)y = 1.0206k = 38 percentovershoot=100*(y-C)/Cpercentovershoot = 2.0650超调量 调节时间0.2300 (s) g10=-feedback(g2*g3,-g1*100*(0.03*1/g3+1),1)Transfer function: -s - 1000- -扰动输入传递函数s3 + 1020 s2 + 35000 s + 500000 step(g10) c,t=step(g10); y,k=max(c)y = 0k = 1 y,k=min(c)y = -0.0020k =38对单位阶跃扰动的最大响应值：c（t）= 2.0*10-3（s）。三、PD控制器的性能分析根轨迹法利用根轨迹图，分析K3的变化对系统性能指标的影响，选取能够满足下列指标要求的K3值 G3=series(G,tf(1 1,1) Transfer