Angular rate

K-absorption spectrum of yttrium in YH3, which was mechanically treated in a ball planetary mill during 20 min. with angular rate of 1630 rot./min. is shown in Fig. 6 (c). This absorption spectrum, as seen from the picture, is shifted relatively to the spectrum of untreated YH3 hydride to the side of lower energies, which in accordance with the found out correlation has to testify to thermal stability of reduction of treated yttrium hydride. Actually, we determined by the method of hydrogen thermal desorption, that as a result of mechanic dispersing of this hydride its temperature of decomposition decreased more than on 300 °C (Fig. 7), i.e. the... 

Case Study II Poly-Si Surface Micromachining and Angular Rate Sensor... 

FIGURE 14.4 Structure of the angular rate sensor (gyro), fabricated in poly-Si micromachining. 

Simulations of the angular rate sensor have proved that the required specifications of the gyro can only be fulfilled when the difference between/drive and/sense IS less than 300 125 Hz. The dependence of drive frequency and sense frequency on EPI poly-Si thickness is shown in Fig. 14.8. /drive is nearly... 

FIGURE 14.8 Simulation of angular rate sensor drive and sense frequencies versus EPI-poly thickness. Spedlications of the g5TO can only be fulfilled for A/= 300 125 Hz that is, EPI-poly thickness after CMP has to be 11.0 0.27 rm. 

Comfort/ - angular rate - rain sensor (Europe) ... 

Angular-rate sensors are relatively new in automotive applications. They were first used in 1995 in vehicle dynamics control systems. More recent applications include navigation systems and rollover systems. Since all these systems are still in a growth phase, these sensors have a large market potential in coming years. For the year 2000, the market is estimated to be approximately 250 million, growing to more than 700 million in 2005. 

As an example, we describe the work flow for developing an angular-rate sensor, which is implemented in automobile navigation systems as a supplementary inertial-detection system in addition to GPS. (Sensors of similar design are also used in passenger-restraint systems for rollover detection.)... 

If an angular velocity is applied perpendicular to the vertical axis, the rotor responds with a vibrating precession, due to the principle of conservation of angular momentum (Fig. 4.1.6). This tilt oscillation has the same frequency as the inplane rotational vibration and an amplitude proportional to the angular rate to be measured. This motion is detected by electrodes located beneath the structure as a change in capacitance. 

According to the typical work flow for developing MEMS sensors (Fig. 4.1.4), design of the angular-rate sensor system starts from the required specifications, with system-level design, and comprises the steps described in this section. 

This angular-rate sensor example is continued in Section 4.1.6, where we take into account additional considerations necessary for obtaining robust designs. But first, we need to give some background on robust design. 

Neul, A low cost angular rate sensor for automotive applications in surface micromachining technology, Proc. Advanced Microsystems for Automotive Applications 99 (eds D. E. Ricken, W. Gessner), Springer, Berlin, Germany, 1999, 239-250 ... 

R. Neul, A low cost angular rate sensor in Si-surface micromachining technology for automotive applications SAE Technical Digest Series 990931, 1999. 

Fig. 5.1.20 Bulk-micromachined angular rate sensor from SensoNor asa with asymmetric spring for setting up an in-plane excitation movement by applying a vertically oriented electrostatic force...

In practice, when actually manufacturing acceleration sensors by surface micromachining, the overall process flow outline must be filled in with the detailed specific processes - as discussed in the previous sections. This is described below, based on an actual production process used for acceleration sensors [26] and an angular rate sensor made solely by surface micromachining [27, 28]. 

Fig. 5.8.2 Typical plastic mold packages meter right angular rate sensor)...

As these networked sensors become more prevalent, clusters of sensors at a given node are also likely to be developed, which will introduce additional functions to the sensor node. For example, in the vehicle dynamics application, both inertial and angular rate sensors will be required. It is likely that these will be clustered into a single module that communicates to the ECU via the sensor network. 

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