Capacitive accelerometers play a fundamental role in modern industry. It detects acceleration by measuring the displacement of an inertial mass. This is achieved by measuring the variation in capacitance between two electrodes. It is essential in many sectors, from aerospace to automotive.

Thanks to its high sensitivity and bandwidth from 0 Hz to 1 kHz, it excels at detecting low-frequency vibrations. Its robustness enables it to withstand up to 20,000 g for a 10 g model. Perfect for demanding applications.

Syscom-Prorep, a specialist in industrial electronic solutions for 30 years, offers a variety of capacitive accelerometers. These sensors deliver 0.3% linearity and stable performance. They work well over a wide temperature range, from -54°C to 121°C.

MEMS technology has enabled the emergence of more accurate and stable accelerometers. These sensors are crucial for aircraft vibration testing, space vibration measurement and vehicle dynamics analysis.

Key points to remember

  • Measures acceleration by capacity variation
  • High sensitivity for low-frequency vibrations
  • Ruggedness up to 20,000 g for 10 g model
  • MEMS technology for stable, accurate measurements
  • Aerospace and automotive applications
  • Performance over a wide temperature range (-54°C to 121°C)
  • Syscom-Prorep's expertise in industrial solutions

Introduction to accelerometers and their importance in industry

Accelerometers are essential in modern industry. They enable precise acceleration detection in a variety of fields. Their technological evolution has opened up new possibilities for embedded systems and connectivity solutions.

Definition and operating principle

An accelerometer is an inertial sensor that measures the acceleration of an object. It uses a test mass suspended between two parallel plates. Displacement of this mass under the effect of acceleration causes a variation in capacitance, enabling acceleration to be detected.

Main industrial applications

Accelerometers are used in many industrial sectors:

  • Structural monitoring of buildings
  • Machine vibration control
  • Autonomous vehicle navigation
  • Constant acceleration measurement in aerospace

Technological developments in motion sensors

Technological advances have led to the development of MEMS (Micro-Electro-Mechanical Systems) accelerometers. These sensors offer high sensitivity and an adapted measurement range. They incorporate electronic circuits to compensate for the effects of temperature and ensure optimum performance.

Modern accelerometers can be powered by an unregulated DC voltage source from 6 to 28 VDC. Their robust design, with hermetically sealed configuration and mechanical stops, makes them suitable for demanding industrial environments.

Capacitive accelerometer: basic principles

The capacitive accelerometer, a capacitive transducer, transforms movements into electrical signals. Its unique structure and sensing mechanism make it a valuable tool for capacitive measurement in many industrial applications.

Structure and internal components

A capacitive accelerometer consists of fixed and movable plates, forming capacitors. When subjected to acceleration, the moving plates move. This changes the capacitance between the elements. This variation is proportional to the acceleration applied.

Capacitive sensing mechanism

Detection is based on measuring changes in capacitance. Specialized circuits, such as impedance bridges or oscillators, convert these variations into usable electrical signals. Sensor sensitivity is determined by the slope of its calibration curve.

Advantages over other technologies

Capacitive accelerometers offer several advantages:

  • High precision and linearity
  • Low energy consumption
  • Good thermal stability
  • Measure static and dynamic accelerations

These features make them ideal for a variety of industrial applications. They are ideal for vibration monitoring and motion control. Their reliability and versatility make them essential in many sectors where precision is crucial.

Key technical data

Capacitive accelerometers, based on MEMS technology, provide state-of-the-art instrumentation for a variety of applications. They feature precise technical specifications, crucial for ensuring reliable measurements.

Measurement range and sensitivity

The measurement range of a capacitive accelerometer can extend to 200 g, with a sensitivity of 10 mV/g. This combination ensures accurate measurements in a wide range of environments, from automotive to aerospace.

Bandwidth and resonant frequency

Typical bandwidth extends from 0 to 850 Hz, ideal for detecting vibrations in many industrial applications. This frequency bandwidth enables fine motion detection, essential for precision instrumentation.

Precision and resolution

MEMS technology offers outstanding precision. With dimensions of 21.6 x 21.6 x 7.62 mm and a weight of 25.6 g, these sensors offer high resolution. Their ability to measure small variations, even after an impact, makes them indispensable for structural monitoring.

Capacitive accelerometers excel in extreme conditions, operating from -54°C to +121°C. This robustness, combined with their precision, is contributing to their growing adoption in industry. The market is projected to reach 3.2 billion USD by 2030.

Application areas and practical uses

Capacitive accelerometers are proving indispensable in many industrial sectors. They embody a versatile motion sensor, essential in today's embedded electronics. Their applications range from the automotive and manufacturing industries to aerospace.

In the automotive sector, these sensors assess vehicle stresses. They determine dynamic increase coefficients and estimate component service life. On-board electronics in modern cars use them to improve safety and performance.

Capacitive accelerometer in on-board electronics

The aerospace industry uses them for structural analysis of aircraft. They facilitate modal analysis, identify structural characteristics and assess aircraft serviceability. Monitoring structural behavior is crucial to ensuring flight safety.

In the manufacturing sector, capacitive accelerometers monitor machines. They measure accelerations in one, two or three directions, providing a complete picture of equipment movements. This data is invaluable for preventive diagnostics and production quality control.

Consumer electronics also benefit from this technology. Wearables and mobile devices incorporate capacitive MEMS accelerometers for a variety of functions, from screen rotation to step counting.

Measurement technologies and signal conditioning

The capacitive accelerometer, an essential microelectronic device, requires sophisticated signal processing to provide accurate measurements. This process involves several crucial steps to optimize sensor performance.

Capacitive signal processing

The heart of the capacitive accelerometer lies in the variation in capacitance due to the movement of a diaphragm under the effect of external forces. This variation translates into an electrical signal that must be processed with care.

Filtering and amplification

Filtering eliminates unwanted noise, improving signal quality. Amplification increases signal amplitude to facilitate further processing. These steps are crucial for obtaining reliable measurements in a wide range of applications, from aerospace to automotive.

Output interfaces

Capacitive accelerometers offer different output interfaces:

  • Analog: for direct signal readout
  • Digital: for easy integration with modern control systems
  • Differential: for better rejection of common noise

The choice of interface depends on the specific application and accuracy requirements.

Mastery of these measurement and signal conditioning technologies is essential to exploit the full potential of capacitive accelerometers in advanced industrial applications.

Installation and commissioning

The installation of an inertial sensor, such as a capacitive accelerometer, requires meticulous attention to ensure impeccably accurate measurements. Meticulous implementation is essential to optimize the performance of this data acquisition technology.

Mechanical assembly

Mechanical assembly plays a decisive role in measurement reliability. Here are some key points to consider:

  • Ensure that the mounting surface is flat (tolerance 0.00076 mm)
  • Recommended surface roughness is 8 x 10-4 mm
  • Check the perpendicularity of the mounting hole (± 6 minutes)
  • For high frequencies, use a drop of oil between the surfaces.

Wiring and connections

Proper wiring is crucial to prevent interference:

  • Use Lemo (4-pin) or Bendix (6-pin) connectors
  • Connect cable shield to ground
  • Avoid ground loops with a floating connection
  • Secure the cable to prevent damage from movement

Initial calibration

Calibration is essential to guarantee measurement accuracy:

  • The shunt must generate 80% of the sensor's rated output.
  • Perform an annual calibration check
  • Use a display during installation to monitor output

Meticulous installation of your inertial sensor ensures reliable and accurate measurements, crucial for efficient precision instrumentation.

Maintenance and calibration

Regular maintenance of capacitive transducers is essential to ensure reliable acceleration detection. Today's capacitive accelerometers are designed for durability, with performance remaining stable, varying by less than 2% over several years. This, under normal conditions, guarantees their reliability.

An initial factory calibration provides detailed documentation for each sensor. Periodic sensitivity checks are recommended to maintain accuracy and detect any anomalies. An effective method is to measure the output signal when the sensor is rotated 180°.

For a more thorough inspection, a portable calibrator with vibration table capable of generating 10 m/s² at 159.15 Hz is ideal. It enables the entire measurement system to be tested. This method is particularly beneficial prior to a major data acquisition campaign.

Several technical guides are available for optimizing the use of capacitive accelerometers:

  • TN-2: Integrated self-test function
  • TN-4: Polarization voltage diagnostics
  • TN-5: Appropriate assembly techniques
  • TN-7: Long cable management

These resources are designed to improve the performance and lifetime of acceleration detection sensors in various industrial sectors.

Syscom-Prorep solutions for integration

Syscom-Prorep stands out for its integrated solutions for accelerating capacitive accelerometers in embedded electronics. Their mastery of MEMS technology and 30 years' experience in the field guarantee seamless integration for a variety of industrial applications.

Technical support services

The Syscom-Prorep team supports customers at every stage, from sensor selection to installation. They ensure smooth integration of capacitive accelerometers. Their approach is personalized, tailored to the specific requirements of each project.

Support and expertise

The experts at Syscom-Prorep have in-depth expertise, particularly in ISO 16063-11 standards for vibration calibration. They use state-of-the-art equipment, such as Polytec CLV-1000 laser vibrometers, for precise measurements. This expertise guarantees reliable results, suitable for both high- and low-frequency applications.

Customized solutions

Syscom-Prorep creates tailor-made solutions to meet the specific needs of each customer. Their capacitive accelerometers offer exceptional resolution, extended measurement range and wide frequency bandwidth. These compact, lightweight sensors are ideal for detecting structural damage or analyzing structural vibrations.

Conclusion

Capacitive accelerometers are essential in today's technology. Their microelectronic technology enables precise measurement of acceleration and vibration. When combined with gyroscopes, their effectiveness in navigation and user interaction is enhanced.

Their usefulness extends to many fields. They improve vehicle safety, the interactivity of electronic devices and innovation in many sectors. Their small size and low power consumption make them ideal for portable devices and connected objects.

Despite challenges such as sensitivity to mechanical vibration and temperature variations, the future of capacitive accelerometers is bright. Continuous progress in their design and integration promises new applications and performance. For assistance or information on integrating these sensors into your projects, contact Syscom-Prorep on +33 1 60 86 80 04 or by email at contact@syscom-prorep.com.

FAQ

What is a capacitive accelerometer?

A capacitive accelerometer is a device that detects acceleration using capacitive measurement technology. It plays a crucial role in modern industry, thanks to its accuracy and reliability.

How does a capacitive accelerometer work?

This type of accelerometer works by measuring variations in electrical capacitance. Fixed and moving electrodes are involved. When the sensor undergoes acceleration, the distance between these electrodes changes. This change in distance modifies the capacitance, enabling the acceleration to be measured.

What are the advantages of capacitive accelerometers over other types?

They offer greater sensitivity and precision. They are also more thermally stable. Their robustness and low power consumption make them ideal for many industrial applications.

What are capacitive accelerometers used for?

They are used in many sectors. These include the automotive, aerospace, consumer electronics and manufacturing industries. They are essential for safety, navigation and machine vibration monitoring.

What is MEMS technology in capacitive accelerometers?

MEMS (Micro-Electro-Mechanical Systems) technology is used in the manufacture of capacitive accelerometers. It enables the creation of miniaturized sensors. These sensors combine mechanical and electronic components on the same substrate, offering high precision in a compact format.

How to install a capacitive accelerometer correctly?

Installing a capacitive accelerometer requires precise mechanical assembly and appropriate wiring. Initial calibration is also crucial. It is essential to follow the manufacturer's instructions and consider the operating environment to ensure accurate measurements.

How important is maintenance for capacitive accelerometers?

Regular maintenance is essential to maintain the accuracy and reliability of capacitive accelerometers. This includes periodic checks, recalibration and sometimes replacement of components. These measures ensure optimum long-term performance.

How can Syscom-Prorep help with the integration of capacitive accelerometers?

With 30 years' expertise in industrial electronics solutions, Syscom-Prorep offers technical support services. They provide support and customized solutions for the optimal integration of capacitive accelerometers in various industrial environments.

What are the key technical features to consider when choosing a capacitive accelerometer?

Important characteristics to consider include measurement range, sensitivity, bandwidth, resonance frequency, accuracy and resolution. The choice depends on the specific application and conditions of use.

How does signal processing improve the performance of capacitive accelerometers?

Signal processing, including filtering and amplification, improves measurement quality. It reduces noise and increases accuracy. Appropriate output interfaces enable efficient integration into control and data acquisition systems.

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