Types Of MEMS Gyroscope
MEMS gyroscopes come in various configurations, each designed for specific applications and performance requirements. Here are the main types:
Solid MEMS Gyroscope
This type of gyroscope uses a stable rotating solid mass to sense angular velocity. A small spinning rotor inside the device maintains its orientation due to gyroscopic effect principles. It is extensively used in aerospace and defense applications due to its robust design and accuracy.
Coriolis Effect MEMS Gyroscope
Coriolis MEMS gyroscopes are the most common type used in consumer electronics. According to Coriolis's principle, when a vibrating structure is subjected to rotation, the Coriolis effect causes a shift in the vibration pattern. This type is widely used in smartphones, drones, and automotive systems.
Tuning Fork MEMS Gyroscope
A tuning fork gyroscope uses a vibrating fork-shaped element to measure angular velocity. When the gyroscope is rotated, the vibrational branches of the crystal fork are affected. One fork's vibrating arms will increase in speed, while the other's will slow down. It is popular in applications needing low-power and cost-effective solutions, such as wearables and instrumentation.
Ring Laser Gyroscope
Although not strictly a MEMS device, a ring laser gyroscope operates on principles similar to those of a MEMS gyroscope. While it does not fall into the MEMS category due to its laser medium, some opt for it in high-precision applications. In this device, two coherent laser beams travel in opposite directions around a triangular path.
Vibrating Beam MEMS Gyroscope
This gyroscope senses the angular velocity through vibrating micro-beams. Under the influence of rotation, the Coriolis force causes a part of the beam to deflect. This type is still in a relatively experimental phase but shows potential for applications in inertial navigation and robotics.
Industry Applications of MEMS Gyroscope
Aerospace and Defence
MEMS gyroscopes in aerospace and defense applications are crucial for navigation and guidance systems. They provide critical data for missile guidance systems, satellite positioning, and aircraft navigation. Solid-state MEMS gyroscopes are especially favored in this industry for their robustness and accuracy.
Automotive
In the automotive sector, MEMS sensors are used extensively in stability control systems, airbag deployment sensors, and navigation systems. In modern vehicles, MEMS gyroscopes assist with the direction and angular velocity, contributing to advanced driver assistance systems (ADAS). These systems improve the vehicle's safety and reliability by providing real-time positional feedback.
Consumer Electronics
The consumer electronics industry is one of the largest users of Coriolis MEMS gyroscopes. These are integrated into smartphones, tablets, and gaming consoles to enhance user experience. In smartphones, they enable features like screen rotation, augmented reality applications, and camera stabilization.
Agriculture and Farming
MEMS gyroscopes are used in precision agriculture, particularly in auto-steering systems for tractors and other agricultural machinery. In precision farming, these sensors improve the accuracy of field mapping and crop monitoring to maintain efficiency and reduce waste.
Medical Devices
MEMS gyroscopes play a vital role in medical devices such as surgical robots and mobile diagnostic equipment. They provide the precision needed for stabilizing instruments during surgery or tracking body movements in diagnostics. In this field, accuracy and reliability are the top priority, which is why solid-state gyroscopes are favored.
Product Specifications and Features of MEMS Gyroscope
Technical Specifications
- Angular Rate Sensitivity: This refers to the ability to detect angular velocity, which is typically measured in degrees per second. Most gyroscopes intended for multiple applications have an angular rating sensitivity of about 3 to 20 degrees/sec.
- Bias Stability: This is the ability to maintain precision without drifting over time. Bias stability is a critical parameter in inertial navigation where precision is key. Consumer-grade gyroscopes have about 0.05 to 0.1 degrees/hour stability.
- Output Bandwidth: The output bandwidth is the rate at which the sensor can deliver data. Typical output bandwidths range from 100 Hz to 2KHz, which is acceptable for most applications.
- Power Consumption: MEMS gyroscopes are favorable because they consume low power, roughly between 5mW to 15mW. This makes them prime candidates in battery-operated and energy-conserving devices like smartphones and wearables.
- Operating Temperature Range: This refers to the temperature range where MEMS gyroscopes can operate effectively. Most gyroscopes have a range of about -40°C to 85°C, suitable for various industries.
How to Use
- Calibration: Before use, the gyroscope must first be calibrated to determine bias and sensitivity. Proper calibration of the gyroscope allows for more accurate readings and eliminates errors.
- Power Connection: Next, the power connection needs to be established. Since most gyroscopes consume low power, a small battery or energy source can power them.
- Data Acquisition: Once the power connection has been established, data can be retrieved. The gyroscope will measure angular velocity and output this as electrical signals. This output will be in the form of raw data that needs to be processed for interpretation.
- Integration with Other Systems: Finally, the gyroscope output is integrated into other systems. In smartphones, the angular velocity data helps stabilize camera functions and enhances gaming and AR experiences.
Maintenance and Repair
- Regular Calibration: One major maintenance tip is to conduct regular calibration. Regular calibration helps keep data accuracy and bias errors at a minimum.
- Shield from Extreme Conditions: Shielding the gyroscope from extreme conditions such as high temperatures, excess moisture, and dust is vital. Although they have a robust design, exposure to such elements can impair the sensor.
- Software Updates: Regular software updates on devices using MEMS gyroscopes can theoretically improve their performance. This is done by optimizing data processing algorithms and reducing power consumption.
- Physical Inspection: Conducting physical inspections to look for any visible damage is another way to ensure the device is well kept. Look for signs of wear on the housing or any physical damage to the sensor.
Quality and Safety Considerations of MEMS Gyroscope
Quality Considerations
- Data Accuracy: Data accuracy is the most important quality consideration when using a gyroscope. Accurate data is vital in applications such as aerospace and defense, where there is no room for error. The slightest deviation caused by poor quality will lead to catastrophic failures in these spaces.
- Noise Performance: In this context, noise refers to the unwanted electrical fluctuations that give a wrong reading of angular velocity. High noise performance leads to less deviation in reading, which pure quality gyroscopes prioritize.
- Durability: MEMS gyros are built to withstand extreme conditions such as fluctuations in temperature and pressure. However, quality ones are also durable in regular conditions and have a robust design to withstand wear and tear.
- MTTF and MTTG: Mean time to failure and mean time to gyro as quality metrics are used to measure the reliability of the gyroscope over an extended period of usage.
Safety Considerations
- Impact Resistance: Although most MEMS gyros are small and light, they normally come with sturdy and compact designs to ensure effective impact resistance. Because most of these applications are used in critical conditions, any failure caused by the impact will have dire consequences.
- Electromagnetic Interference (EMI) Shielding: EMI can cause erratic behavior in electronic devices, so shielding them out is essential. Effective EMI shielding will prevent erratic readings and ensure safety in all applications.
- Environmental Sealing: Proper environmental sealing of the gyroscope ensures that no debris and moisture get inside and cause malfunction. This is especially useful for ones that operate in harsh outdoor spaces, as they are often exposed to dust and water.
- Consistency in Performance: In critical applications, ensuring that the sensor will consistently perform within specified parameters without unexpected drift or variation is vital for safety.
Q&A
Q1. What is a MEMS gyroscope used for?
A1: MEMS gyroscopes are used for various applications, with their most common being angular velocity measurement. They are widely used in consumer electronics, automotive systems, aerospace navigation, and robotics due to their compact size and versatility.
Q2. How long do MEMS gyros last?
A2: Most quality MEMS gyros have a typical lifespan of 10-20 years under normal operating conditions. Some last longer, for instance in aerospace applications, as they are designed to be more robust; often they can last for over 20 years.
Q3. Can MEMS microscope slides be repaired?
A3: Repairing a MEMS gyroscope is often challenging, as these sensors are miniaturized electronic components. In most cases, replacement is more practical. That said, some components, like the protective housing, can be repaired or replaced.
Q4. What materials are commonly used in gyroscope construction?
A4: Materials used for constructing gyroscopes depend on the type. MEMS gyros are silicon-based, while ringing laser gyros use glasses or crystal materials. Other gyros use ceramic for the rotor and stainless steel for the outer casing.
Q5. What causes a gyroscope's drift?
A5: Drift happens when uncorrected accumulated errors during the integration of the angular velocity occur over time. Sensor bias, environmental factors like temperature change, and misalignment all contribute to drift.
