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PPF controller. The second mode energy experienced a small increase rather than a decrease. This is
mainly due to the switching nature of the SMC.
In the controller law, the parameter p is set to be a constant of 1. The maximum control voltage is
assumed to be 100V. The phase plane plot of the closed-loop system is shown in Figure 9 and the
corresponding control voltage is shown in Figure 10. It can be clearly seen from the phase plane plot that
the system trajectory converges to the equilibrium point. The control objective is achieved.
with control
with control
without control
time(s)
Fig. 7 Sliding mode control response
10 20 30 40
Frequency (Hz)
Fig. 8 PSD plot of uncontrolled and SMC
controlled model building for 5-15 sec
"5
o
Phase plane plot
Control voltage
Displacement(V)
Fig 9 Phase plane plot of the SMC
time(s)
Fig 10 Control voltage
4. CONCLUSION
The paper experimentally demonstrated the vibration suppression of a 3-floor model building using the
positive position feedback (PPF), strain rate feedback (SKF), and sliding mode control (SMC). Since the
same computerized excitation was used all the tests, the energy level drop in the power spectrum density
plots as compared with uncontrolled case is used as one index to examine the effectiveness of the control
method. The first mode is the dominant mode and is the main concern for vibradon control. Increased
vibration damping is observed in all control designs. A maximum increase in damping ratio of 540% was
obtained and energy level drop of 51dB was achieved in the case of PPF control. The PPF control was the