Fizoptika Malta MINIATURE FOG IMUs Lightweight Low power ITAR free * Compared to a US quarter dollar Visit us at Oceanology London 2024 (Booth A203), Xponential 2024 (Booth 3652) or fizoptika.com electric charges or outputs proportional to the level of acceleration imparted. Additionally, numerous form factors of the core MEMS components have been developed over the years. Among MEMS vibratory gyroscopes, one of the most popular is the tuning-fork type, which is designed with two geometrically identical structures that are suspended and driven with equal amplitude but oriented in opposing directions. Electrostatic actuation is used such that rotational movements perpendicular to the driving axis produce a Coriolis force, which shifts the driving motion in the direction of the sensing axis, with sensing then performed capacitively, resulting overall in generally higher measurement sensitivity levels than other designs. More popular still are vibratory MEMS gyroscopes using ring structures, some of which originated as non-MEMS, piezoceramic structures, before being reimagined as a silicon MEMS device. Ring gyroscopes are more symmetrical than most other gyroscope designs, and hence provide advantages in terms of precision, resolution, thermal stability and sensitivity over other kinds. When angular rate is imparted on the ring, Coriolis force causes each point on it moving outwards to ‘bend’ in one direction, and the points moving inward will ‘bend’ in the opposite direction. Vibrating modes hence move around the ring, at an angle proportional to the rotational velocity, and generate a signal that can be processed into inertial data. Devices measuring inertia this way are now achieving bias instabilities below 0.1°/hr, and couple with accelerometers whose bias instabilities are below 15 µg. MEMS accelerometers, whether capacitive or piezoresistive, tend to operate using a proof mass suspended on flexures between two reference masses (these can be shaped as plates, tuning forks, ‘combs’ of interdigitated fingers resembling interleaved tuning forks or other structures), with linear accelerations resulting in the proof mass flexing away from one reference mass and closer to another. That alteration in distance results in measurable changes in either capacitance (if using a capacitive accelerometer) or resistance (in a piezoresistive) accelerometer proportional to the rate of acceleration. Both piezoresistive and capacitive accelerometers remain popular types across aircraft and robotics applications. Beyond these core sensing elements, MEMS developers are continuing to work on the surrounding componentry. For instance, as some uncrewed systems operate with higher dynamics, to the point of being dynamically unstable (as highly manoeuvrable aircraft are sometimes designed), higher inertial data update rates are increasingly prized. Although, to an extent, update IMUs, gyros and accelerometers | Focus MINIATURE Visit us at Oceanology London 2024 (Booth A203), Xponen�al 2024 (Booth 3652) or fizop�ka.com FOG IMUs • ITAR free • Lightweight • Low power * Compared to a US quarter dollar
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