Ch. 7 Steady-State Errors

Front 1

1. Name two sources of steady-state errors.

Back 1

1. Nonlinear, system configuration

Front 2

2. A position control, tracking with a constant difference in velocity, would yield how much position error in the steady state?

Back 2

2. Infinite

Front 3

3. Name the test inputs used to evaluate steady-state error.

Back 3

3. Step(position), ramp(velocity), parabola(acceleration)

Front 4

4. How many integrations in the forward path are required in order for there to be zero steady-state error for each of the test inputs listed in the test inputs used to evaluate steady-state error.

Back 4

4. Step(position)-1, ramp(velocity)-2, parabola(acceleration)-3

Front 5

5. Increasing system gain has what effect upon the steady-state error?

Back 5

5. Decreases the steady-state error

Front 6

6. For a step input the steady-state error is approximately the reciprocal of the static error constant if what condition holds true?

Back 6

6. Static error coefficient is much greater than unity.

Front 7

7. What is the exact relationship between the static error constants and the steady-state errors for ramp and parabolic inputs?

Back 7

7. They are exact reciprocals.

Front 8

8. What information is contained in the specification?

Back 8

8. A test input of a step is used; the system has no integrations in the forward path; the error for a step input
is 1/10001.

Front 9

9. Define system type.

Back 9

9. The number of pure integrations in the forward path

Front 10

10. The forward transfer function of a control system has three poles at -1,-2 and -3. What is the system type?

Back 10

10. Type 0 since there are no poles at the origin

Front 11

11. What effect does feedback have upon disturbances?

Back 11

11. Minimizes their effect

Front 12

12. For a step input disturbance at the input to the plant, describe the effect of controller and plant gain upon minimizing the effect of the disturbance.

Back 12

12. If each transfer function has no pure integrations, then the disturbance is minimized by decreasing the
plant gain and increasing the controller gain. If any function has an integration then there is no control over
its effect through gain adjustment.

Front 13

13. Is the forward-path actuating signal the system error if the system has nonunity feedback?

Back 13

13. No

Front 14

14. How are nonunity feedback systems analyzed and designed for steady-state errors?

Back 14

14. A unity feedback is created by subtracting one from H(s). G(s) with H(s) -1 as feedback form an
equivalent forward path transfer function with unity feedback.

Front 15

15. Define, in words, sensitivity and describe the goal of feedback-control-system engineering as it applies to sensitivity.

Back 15

15. The fractional change in a function caused by a fractional change in a parameter

Front 16

16. Name two methods for calculating the steady-state error for systems represented in state space.

Back 16

16. Final value theorem and input substitution methods