A new silicon rate gyroscope

A new silicon rate gyroscope of small size, low cost, and high performance is described. The device is called MARS-RR, which means Micromachined Angul ar Rate Sensor with two Rotary oscillation modes. First prototypes, MARS-RR 1 yielded random walk and bias stability as low as 0.14 deg/h and 65 deg/h, respectively. The rate equivalent rms noise corresponds to a resolution of 0.05 deg/s in a 50 Hz bandwidth. This performance is achieved by a new sen sor design featuring decoupling of the actuation and the detection oscillat ion modes. Because of decoupling, the modes mechanical and electromechanica l crosstalk, one main error source of micromachined gyros, can be reduced a nd therefore the zero rate output (ZRO) almost disappears. Despite the smal l sensor area of 6 mm(2), the detection capacitance amounts to approximatel y 3 pF. Thus, subatomic deflections are detectable and a high sensitivity i s achieved. MARS-RR1 was manufactured within the Bosch Foundry process [M. Illing, Micromachining Foundry Designrules, Version 1.0, Bosch Mikroelektro nik; M. Offenberg, H. Munzel, D. Schubert, B. Maihofer, F. Larmer, E. Mulle r, O. Schatz, J. Marek, SAE Technical Paper Series, 960758, SAE 96, The Eng ineering Society for Advancing Mobility Land Sea Air and Space, 1996, repri nted from Sensors and Actuators, 1996 (SP-1133), p. 35; M. Offenberg, F. La rmer, B. Elsner, H. Munzel, W. Riethmuller, Novel Process for a Monolithica l Integrated Accelerometer, Transducer '95, Eurosensor IX, 148-C4, pp. 589- 592] and therefore it was possible for us to reduce the development time co nsiderably. (C) 1999 Elsevier Science S.A. All rights reserved.