Active Vibration Control Using Proof Mass Actuators
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Active Vibration Control Using Proof 20 Mass (Inertial) Actuators 0 Tuned damping Tuned dynamic Proof mass actuators (PMAs) are A proof mass actuator -20 absorption used to add tuned damping and (PMA) is comprised of tuned dynamic absorption to a parallel arrangement of test structure as well as the rear spring and an active -40 sub-frame of an all-wheel drive element pushing/pulling Magnitude, dB vehicle. -60 against a mass (known as The choice of active vibration proof mass or inertial mass). -80 control strategy, with a PMAs as Some damping is also built the actuator, depends on uncontrolled in its make-up. controlled whether the PMA’s natural -100 PMAs generate force by 100 200 300 400 500 600 700 800 900 frequency is placed below or Frequency, Hz pushing against a within the frequency(ies) of the Figure 1 FRFs mapping the perturbation input to the suspended mass and thus structure targeted for acceleration without (dashed line trace) and with (solid line do not need an anchor damping/dynamic-absorption. A trace) TMD/DA and active control sample of such controllers are: point. Active Vibration Control of a Rear Sub-frame 1. With the natural frequency of the PMA set substantially Two electromagnetic lower than the natural PMAs were used to frequency of the structure PMA actively absorb the forced targeted for vibration of the rear damping/absorption. This arrangement enables the control differential of a car and designer to use traditional and familiar active control thus lower its transmission to the schemes. 2. With the natural frequency of the PMA set within (or at) the vehicle cabin. An active frequencies of the structure targeted for damping/dynamic- DA controller was used in 2 PMAs installed on rear sub- absorption, the dynamics of the actuator will be introduced this application. frame into the dynamics of the structure. This in turn, makes the Using the acceleration measured by the feedback sensor on the synthesis of active control strategy somewhat more front bushing of the rear sub-frame, the frequency response involved/elaborate. The advantage of such strategy is lower functions mapping the voltage driving a shaker (installed on the power consumption of the actuator. drive shaft) to the aforementioned accelerations were Active Vibration Control of a Test Structure measured. Figure 2 shows the magnitude of these FRFs with the control loop open (blue/solid line traces) and closed (red/dashed With the goal of adding tuned damping and/or tuned vibration line traces). The presence of a zero (a notch) at 420 Hz on the absorption to a test structure, two controllers dubbed TMD and FRF of they system with controls (the red trace) points to the DA fashioned after the dynamics of a passive tuned mass damper effectiveness of the active vibration control scheme in absorbing and dynamic absorber were designed and implemented, vibration at the frequency of interest. experimentally. One piezoelectric proof mass actuator was used in this experiment. vibration of passenger side with both sides control -10 A TMD controller was used to damp the 3rd mode of the uncontrolled controlled structure. Moreover, with an external excitation force (causing -15 forced vibration) at the frequency of 750Hz, a DA controller tuned to that frequency was used to absorb the corresponding -20 forced vibration of the structure. -25 The frequency response functions (FRFs) mapping the disturbance to the measured acceleration of the uncontrolled mag, dB -30 and controlled structure are shown in Figure 1. Around 20dB -35 damping effectiveness (10 times reduction) is obtained at the target mode. Moreover, at the frequency 750 Hz to which the DA -40 controller was tuned, a substantial absorption of vibration was -45 realized. 200 250 300 350 400 450 500 550 600 freq, Hz Figure 2 FRFs of accelearion of driver side sub-frame busing WWW.DEICON.COM [email protected] PH: +1 937 885 4134 .