Block diagrams worksheet with answers

Free printable Block diagrams worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________   Date: ____________

1.Easy
R(s)12G₂4G₃++8G₁C(s)

The signal R splits into two parallel blocks G₂ = 12 and G₃ = 4. Their outputs meet at a summing junction with the signs shown (+ and +), and the sum passes through G₁ = 8. Find the overall gain T = C/R.

G₁ = 8G₂ = 12G₃ = 4signs: + G₂, + G₃
T =
2.Easy
R(s)+14G₁4G₂C(s)0.25H−

In the block diagram the forward path has the gains G₁ = 14 and G₂ = 4 in series, and the negative feedback path has the gain H = 0.25. Find the overall gain T = C/R.

G₁ = 14G₂ = 4H = 0.25
T =
3.Medium
R(s)+Ks(s + 14)G(s)C(s)−

The plant G(s) = K/(s(s + 14)) is in a unity negative feedback loop. Find the gain K for which the closed loop is critically damped (two equal real poles).

G(s) = K/(s(s + 14))unity negative feedback
K =
4.Medium
R(s)+K(s + 7)(s + 12)G(s)C(s)−

The plant G(s) = K/((s + 7)(s + 12)) is in a unity negative feedback loop. Find the gain K for which the closed loop is critically damped (two equal real poles).

G(s) = K/((s + 7)(s + 12))unity negative feedback
K =
5.Hard
R(s)+Kcontroller+D(s)+3s + 4plantC(s)−

A proportional controller K drives the plant G(s) = 3/(s + 4) in a unity negative feedback loop. A disturbance step of size 0.5 enters at the plant input while R = 0. Find the smallest gain K that keeps the steady-state output at or below 0.075.

G(s) = 3/(s + 4)D = 0.5css ≤ 0.075
K =
6.Hard
R(s)+Kcontroller+D(s)+6s + 2plantC(s)−

A proportional controller K drives the plant G(s) = 6/(s + 2) in a unity negative feedback loop. A disturbance step of size 10 enters at the plant input while R = 0. Find the smallest gain K that keeps the steady-state output at or below 0.3.

G(s) = 6/(s + 2)D = 10css ≤ 0.3
K =

Answer key

  1. 1. T = 128
  2. 2. T = 3.733
  3. 3. K = 49
  4. 4. K = 6.25
  5. 5. K = 5.333
  6. 6. K = 33

Full step-by-step solutions: practise this topic on examproblems.com.