A fully compliant force balanced oscillator

Abstract

Usage of compliant micro mechanical oscillators has increased in recent years, due to their reliable performance despite the growing demand for miniaturization. However, ambient vibrations affect the momentum of the oscillator, causing inaccuracy, malfunction or even failure of these devices. herefore, this paper presents a compliant force balanced mechanism comprising at least a prismatic joint, thereby creating the opportunity for usage of prismatic oscillators in translational accelerating environments. The proposed mechanism entails the symmetric displacement of two coplanar prismatic joints along non-collinear axes via a shape optimized linkage system. Rigid-body replacement with shape optimized X-bob, Q-LITF and LITF joints yielded a harmonic (R>0.999), low frequency (f = 27 Hz) single piece force balanced micro mechanical oscillator (∅35 mm). Experimental evaluation of large scale prototypes showed a limited ratio of the center of mass compared to the stroke of the device (≈0.01) and proper decoupling of the mechanism from the base, as the oscillating frequency of the balanced devices during ambient disturbances was unaffected, whereas unbalanced devices had frequency deviations up to 1.6%. Moreover, the balanced device reduced the resultant inertial forces transmitted to the base by 95%.