A Monolithic Force-Balanced Oscillator

Abstract

Usage of compliant micromechanical oscillators has increased in recent years, due to their reliable performance despite the growing demand for miniaturization. However, ambient vibrations affect the momentum of such oscillators, causing inaccuracy, malfunction, or even failure. Therefore, this paper presents a compliant force-balanced mechanism based on rectilinear motion, enabling usage of prismatic oscillators in translational accelerating environments. The proposed mechanism is based on the opposite motion of two coplanar prismatic joints along noncollinear 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 micromechanical oscillator (∅ 35 mm). The experimental evaluation of large-scale prototypes showed a low ratio of the center of mass (CoM) shift 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%.

Static and Dynamic Balancing of Robots

“…Other work in spatial dynamic balancing includes parallelpiped manipulators by Wu and Gosselin (2005) and the use of counterrotary countermasses in the spatial CaPaMan (Acevedo et al 2012). So far, most if not all dynamic balancing literature considered rigid links, but in specific cases, compliant mechanisms need dynamic balance as well (e.g., Weeke et al 2017).…”