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Bishop, Robert H. - The Mechatronics Handbook [CRC Press 2002] Part 2

Tham khảo tài liệu 'bishop, robert h. - the mechatronics handbook [crc press 2002] part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | FIGURE 5.8 Illustration of Coriolis acceleration which results from translation within a reference frame that is rotating with respect to an inertial reference frame. FIGURE 5.9 Schematic of a vibratory gyroscope. the angular momentum-based gyroscopic mechanics of conventional-scale devices. A Coriolis acceleration results from linear translation within a coordinate frame that is rotating with respect to an inertial reference frame. In particular if the particle in Fig. 5.8 is moving with a velocity v within the frame xyz and if the frame xyz is rotating with an angular velocity of with respect to the inertial reference frame XYZ then a Coriolis acceleration will result equal to ac 2m x v. If the object has a mass m a Coriolis inertial force will result equal to Fc -2mM x v minus sign because direction is opposite ac . A vibratory gyroscope utilizes this effect as illustrated in Fig. 5.9. A flexure-suspended inertial mass is vibrated in the x-direction typically with an electrostatic comb drive. An angular velocity about the z-axis will generate a Coriolis acceleration and thus force in the y-direction. If the external angular velocity is constant and the velocity in the x-direction is sinusoidal then the resulting Coriolis force will be sinusiodal and the suspended inertial mass will vibrate in the y-direction with an amplitude proportional to the angular velocity. The motion in the y-direction which is typically measured capacitively is thus a measure of the angular rate. Examples of these types of devices are those by Bernstein et al. 49 and Oh et al. 50 . Note that though vibration is an essential component of these devices they are not technically resonant sensors since they measure amplitude of vibration rather than frequency. 5.4 Nanomachines Nanomachines are devices that range in size from the smallest of MEMS devices down to devices assembled from individual molecules 51 . This section briefly introduces energy sources structural hierarchy and the .