SuperFlow AutoDyn, Руководство оператора

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Control Modes
11-16 AutoDyn Chassis Dynamometer Operator Manual
Figure 11-2. Closed-Loop Control
The SuperFlow control system functions shown in Figure 11-3 produces a cumulative gain
(P+I+D) to the control mechanism based on the error signal feedback. The control systems cycle at
a 400-hz (2.5-ms) rate.
This PID adjustment procedure assumes the test system and engine/vehicle are operating
properly and that the electrical or hydraulic supply to the test system is sufficient.
On the SuperFlow water brake it is necessary to determine whether the boost valve will be used
and the position of the capacity valve before making any adjustments on the control parameters.
Parameters not listed in this section are best left at the original value or zero.
Preliminary Steps
1. Turn off the I-Gain and the D-Gain by setting them to zero.
2. Start with a P-Gain term at the lower end of the suggested value range for your system.
Begin Adjustment
1. Successively double P-Gain until you reach satisfactory step response. If the P-Gain results in
continuous high-frequency, steady-state instability, lower it by half again.
2. Gradually increase P-Gain until instability reappears, then lower it by 20%.
3. Start with a D-Gain term at the lower end of the suggested value range for your system.
Gradually increase D-Gain (in small increments) until the overshoot is acceptable and steady-
state stability is good.
4. Note the difference between the set point and the actual value. Add 50% to this difference. Set
the I-threshold at this calculated number.
5. Start with an I-Gain term at the lower end of the suggested value range for your system.
Successively double I-Gain until the system settles onto the set point within 3–5 seconds. If
instability occurs, lower I-Gain by half again.
6. Gradually increase I-Gain until instability reappears, then lower it by 20%.
7. Continue adjustment until satisfied. You may need to alter the other parameters (I-Time,
D-Time, Filter, Delay, etc.) to achieve reach exact response desired.
Figure 11-3 illustrates the influence of various parameters on the system response. The
(exaggerated) example shows the effect of entering a new set point (of 2500 rpm) for engine speed
on the actual system response.