Embodiments of the disclosure provide a micromachined mirror assembly for controlling optical directions in an optical sensing system. The micromachined mirror assembly may include a micro mirror configured to direct an optical signal into a plurality of directions. The micromachined mirror assembly may also include at least one actuator coupled to the micro mirror and configured to drive the micro mirror to tilt around an axis. The micromachined mirror assembly may further include one or more objects attached to the micro mirror. The one or more objects may be asymmetrically disposed with respect to the axis to create an imbalanced state of the micro mirror when the micro mirror is not driven by the at least one actuator.