A MEMS (Micro-Electro-Mechanical Systems) micro-gyroscope is a miniaturized version of traditional gyroscopes used for inertial sensing. It utilizes the principles of angular momentum to measure and detect rotational motion in various devices, such as smartphones, navigation systems, drones, and more. The MEMS micro-gyroscope operates based on the Coriolis effect, which is a phenomenon observed when a mass moves in a rotating frame of reference.
Here's a basic overview of how a MEMS micro-gyroscope works:
Structure: The core of a MEMS micro-gyroscope typically consists of a small proof mass (often a tiny vibrating beam or a wheel) suspended by flexible structures within a microfabricated silicon chip. The proof mass can move in response to rotational motion.
Excitation: To set the gyroscope in motion, an actuator applies an oscillating force to the proof mass. This force causes the proof mass to vibrate at a certain resonant frequency.
Sensing: When the device experiences angular velocity or rotational motion about its sensing axis, the Coriolis effect comes into play. The Coriolis effect causes a deflection of the proof mass perpendicular to both the applied force and the angular velocity. This deflection results from the inertial force acting on the moving mass due to its velocity relative to the rotating frame of reference.
Measurement: The MEMS micro-gyroscope detects the proof mass's deflection using various sensing mechanisms, such as capacitive sensing or piezoelectric sensing. Capacitive sensing involves measuring changes in capacitance between the proof mass and fixed electrodes as the mass moves, while piezoelectric sensing relies on measuring the strain in piezoelectric materials that convert mechanical deformation into electrical signals.
Output: The detected deflection generates an electrical signal proportional to the applied rotation rate. This signal can be processed and analyzed to determine the device's angular velocity in the desired axis.
Feedback control: To maintain the gyroscope's oscillation at its resonant frequency and improve accuracy, a feedback control system may be used. This control system adjusts the actuator's excitation frequency based on the gyroscope's output signal, keeping the proof mass oscillating at the desired frequency.
Calibration and Compensation: MEMS micro-gyroscopes often require calibration to compensate for manufacturing imperfections, temperature variations, and other environmental factors that could affect their accuracy. Calibration algorithms and compensation techniques are used to enhance the gyroscope's performance and reduce errors.
Overall, MEMS micro-gyroscopes offer significant advantages over traditional gyroscopes, including their compact size, low power consumption, and compatibility with microelectronics fabrication techniques, making them ideal for various applications where precise and compact inertial sensing is required.