现代控制系统第五章.ppt

The steady-state error for nonunity system: 5.7 Performance Indices A performance index is a quantitative measure of the performance of a system. Optimum control system: when the system parameters are adjusted so that the index reaches an extremum , commonly a minimum value. 1. The integral of the square of the error, ISE Figure 5.25 The calculation of the integral squared error. The integral of the absolute magnitude of the error(IAE) 3. The integral of time multiplied by absolute error (ITAE) 4. The integral of time multiplied by the square error (ITSE) Example 5.6 performance criteria A single-loop feedback control system is shown in figure Where the natural frequency is the normalized value, Figure 5.26 Single-loop feedback control system. (a) Signal-flow graph. (b) Block diagram model. Figure 5.27 Three performance criteria for a second-order system. Example 5.7 space telescope control system Figure 5.28 A space telescope pointing control system. (a) Block diagram. (b) Signal-flow graph. Taking Inverse Laplace transform Therefore , ISE is the minimum and the damp ratio is 0.5. Figure 5.29 The performance indices of the telescope control system versus K3. Figure 5.30 Step responses of a normalized transfer function using optimum coefficients for (a) ISE, (b) IAE, and(c) ITAE. The response is for normalized time, ωnt. Figure 5.31 The foreground camera, which may be either a film or video camera, is trained on the blue cyclorama stage. The electronic servocontrol installation permits the slaving, by means of electronic servodevices, of the two cameras. The background camera reaches into the miniature set with a periscope lens and instantaneously reproduces all movements of the foreground camera in the scale of the miniature. The video control installation allows the composite image to be monitored and recorded live. (Part (a) reprinted with permission from Electronic Design 24, 11, May 24, 1976. Copyright ? Hayden Publishing Co., Inc., 1976.) E