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Accelerometeris an instrument that uses Newton’s second law (Law of inertia) for measuring the acceleration of the carrier line. The accelerometer is one of the first aircraft instruments to be used for measuring aircraft overload. Accelerometer consists of test quality (also known as sensitive mass), support, potentiometer, spring, damper and shell. Accelerometer is commonly used to monitor engine failures and fatigue damage of aircraft structures.The performance levels of different kinds of inertial accelerometers can be divided into navigation level, tactical level and consumer level.
Development of quartz accelerometers
Accelerometers originated in the 1940s, many new accelerometers appeared in the 1950s, and further improved in miniaturization, low cost, multi-function and high stability in the 1960s, MEMS accelerometers were born and became a technological development trend in the late 1970s, and quantum accelerometers began to be developed in the early 21st century. Become a representative of the future ultra-high precision accelerometer.
Application characteristics
The accelerometer is an important part of the inertial measurement unit (IMU), and together with the gyroscope determines the accuracy of more than 90% of the inertial navigation system, its cost, size, weight and power consumption characteristics on the inertial navigation system (INS) application field also has a greater impact, different application fields have different requirements for the use of the accelerometer.
In the flight control system, accelerometer is an important dynamic characteristic correction element.In inertial navigation system, the high precision accelerometer is one of the most basic sensitive components.The accelerometer in different use situations is different in performance. The high precision inertial navigation system requires the accelerometer to have a resolution of 0.001g, but the range is not large. An accelerometer that measures an aircraft’s overload may require a range of 10g, while the accuracy is not high.For example, ER-QA-03A has bias repeatability of 10-50μg, scale factor repeatability of 15-50 PPM and Class II non-linearity repeatability of 10-30μg/g2 with a resolution of 5μg, so it is a good choice for flight control systems.
In the field of oil and gas drilling, the complex formation structure and the continuous upgrading of drilling technology put forward higher requirements for drilling tools. When measuring the attitude parameters of the steering drilling tool, the tool rotation, near-bit vibration and downhole high temperature and pressure will seriously affect the measurement accuracy of the tool attitude parameters. In order to better overcome these factors to obtain accurate measurement data information, ER-QA-03D can not only meet the temperature environment of -40℃ -180 ℃, anti-shock is 500-1000g 0.5ms, but also bias repeatability has 50μg – 250μg .
Key technology
Flexible bracing
The function of flexible support is to convert the change of input acceleration into the change of vibration force of the beam, and then into the change of output frequency. Generally, quartz materials with good strength, high fatigue strength, non-magnetic and good processing ability are used. The design of flexible support combined with the process can be used flat bridge type or arc type. As the key parts of quartz vibration beam accelerometer, the thickness, stiffness and symmetry of flexible joint machining have an impact on the accuracy of the instrument.
Temperature compensation
Temperature is an important aspect that affects the accuracy of quartz accelerometer. The fluctuation of the operating temperature inside the inertial device and the heat source around the shell will cause the error of the output data. The thermal expansion and contraction of the material will deform the structural parts of the accelerometer, and the temperature change will also cause certain changes in the physical parameters of various materials inside the device. The change of the magnetic properties of the torquer will also directly affect the measurement accuracy of the accelerometer. Therefore, through the technology of temperature compensation, the accuracy of the accelerometer can be improved to a certain extent.
Through the above content, we have a preliminary understanding of the related knowledge of the accelerometer other information, for more information, please feel free to contactinfo@ericcointernational.com
The conventional spatial dimension is composed of length, width and height, and the inclination sensor can measure the inclination angle of these three dimensions. Therefore, the inclination sensor can be divided into single axis, two axis and three axis according to the axis. Single-axis tilt sensor can only measure the angle of a certain azimuth; The biaxial tilt sensor can measure the angle of two perpendicular azimuths. The three-axis can measure the angle of transformation of the three directions around the arbitrary axis in three-dimensional space.
Single axis, double axis, triple axis
Inclination sensors usually refer to single-axis tilt sensors, and the theoretical basis of single-axis inclination sensors is Newton’s second law. According to the basic principles of physics, inside a system, velocity cannot be measured, but acceleration can be measured. If the initial velocity is known, the linear velocity can be calculated from the integral, and thus the linear displacement can be calculated. So it’s actually an acceleration sensor that uses the basic principles of inertia. The dual-axis inclination sensor is based on the single axis combined with specific practical requirements, designed and conceived a measurement tool for the angle between two directions.
Based on the direct measurement of the acceleration of the measured object, the biaxial inclination sensor can obtain the linear velocity of the object through integral calculation, and then further obtain the displacement of the object. In essence, the inclination sensor is still an inertial sensor, which follows the inertia law of object motion and the integral calculation method. The two-axis sensor is designed in view of this basic principle, in addition to other measurement principles and measurement methods.
In short, the dual-axis in tilt sensor has the measurement advantages of the single-axis inclination sensor, but also has the measurement effect that can not be achieved by the single axis, with an increasingly wide measurement range. However, the accuracy of the dual-axis inclination sensor is not as good as that of the single axis, and it should be noted that the dual-axis inclination sensor can measure the angle of the X-axis and the Y-axis, but can not measure the X-axis and the Y-axis at the same time, only one axial angle can be measured at a time, the X-axis or the Y-axis, if measured at the same time, it will cause the horizontal axis error and cannot determine its value. Depending on the desired measurement data, you can choose different tilt sensors. In theory, if there are three dimensions of angle change, you need to use a three-axis inclination sensor, but in reality, the three-axis inclination sensor does not exist, more accurately, the two-axis inclination sensor can measure the three-dimensional angle change, without using the so-called “three-axis inclination sensor.” As for why there is no three-axis inclination sensor, it is because when the inclination angle of a incline plane and the X and Y axes is determined, the incline plane is fixed, and there is no possibility of change, that is, the angle between the Z axis is also a definite value.
Taking the X-axis uniaxial tilt sensor as an example, the measuring surface of the sensor can only have an angle with the X-axis, and the inclination plane is fixed on one axis (Y-axis) for rotation. Similarly, the Y-axis uniaxial inclination sensor rotates with the X-axis as the fixed axis. The inclination plane of the biaxial inclination sensor can have an angle with both the X and Y axes, or only one of the axes can have an angle, which is the general case of the inclination plane of the biaxial inclination sensor.
From the above comparative data analysis of the uniaxial and biaxial inclination sensors, it can be seen that the active part of the inclination plane of the biaxial inclination sensor is a point or line, while the single axis can only be a line. For example, the inclination of the vertical wall is the active part of the combination line between the wall and the foundation, which can be measured by the single-axis inclination sensor ER-TS-3160VO; The process of slow toppling of a vertical rod is based on the contact point as the active part, so it is necessary to use the dual-axis inclination sensor ER-TS-4250VOfor measurement. In fact, in the process of tilting the vertical rod, no matter which direction it tilts, one thing is certain, that is, the angle between the tilting position and the original position is the angle between the tilting plane and the horizontal plane, this angle may only be a single X or Y axis inclination, or both, which is why it can only be measured with a dual-axis inclination sensor.
Ericco’stilt sensor can be well used in the wireless positioning anti-theft tracking system.
The vehicle load wireless positioning anti-theft tracking system receives vehicle sensor fusion information through the main controller of the vehicle, obtains GPS satellite positioning information through the GPS module, and then communicates bidirectional with the user terminal through the public mobile communication module through the public mobile communication base station, and sends out local sound and light alarm, GSM wireless transceiver, and realizes mobile and instantaneous control. The sensor fusion information is obtained by the inclination sensor, microwave Doppler sensor trigger infrared sensor, vibration sensor, Hall switch element and air pressure sensor after extraction, fusion and decision, and the user terminal sends control instructions to the master controller after identity verification to realize intelligent zero false alarm automatic monitoring.
Ericco ER-TS-4156DItilt sensor can be well used in the control system, the control part and the execution part, the tilt data acquisition part includes the tilt sensor with GPS module, the signal output interface of the tilt sensor and the MCU analog to digital conversion interface of the control part. The signal end of the ignition lock is connected with the input and output interface of the single chip microcomputer: the single chip microcomputer is connected with the GSM module through the serial port; The user's mobile phone number and other personal information are preset in the single chip computer. The execution part includes the control circuit of the relay that controls the main control power supply of the vehicle and the input and output interface of the single chip microcomputer, and the vehicle alarm system and the input and output interface of the single chip microcomputer. The inclination sensor can not only measure the form attitude of the vehicle body, but also provide the location of the vehicle, provide reliable latitude and longitude for the tracking system, and shorten the detection time.
If you want to learn more about tilt sensors or buy
Introduction Inertial measurement units are one of the most common sensors in navigation. It contains an accelerometer and gyroscope, and sometimes a magnetometer and barometer. The accelerometer is responsible for the acceleration measurement, while the gyroscope is responsible for the angular velocity measurement. Each of these measurements is expressed along the three-axis coordinate system x,y,z. An inertial measurement unit is a device that measures three-axis attitude (or angular velocity) and acceleration. To increase reliability, it is also possible to equip each axis with more sensors. Generally, the IMU should be installed at the center of gravity of the object being measured.
IMUs are commonly used to control modern vehicles, including missiles, robots, submarines, aircraft (attitude and heading reference systems), including unmanned aerial vehicles (UAVs), etc., and spacecraft, including satellites and landers. Developments in recent years have allowed the production of IMU-enabled GPS devices. The IMU allows the GPS receiver to operate when the GPS signal is unavailable, such as in tunnels, inside buildings, or when there is electronic interference.
Operating principle An inertial measurement unit (IMU) works by detecting linear acceleration using one or more accelerometers and measuring angular velocity using one or more gyroscopes. Some also include magnetometers. Pitch, roll and yaw are commonly used as attitude reference systems.
Instructions The IMU is often integrated into an inertial navigation system, which uses raw IMU measurements to calculate the attitude of the drone. A simpler version of the INS, called an Attitude and Heading Reference System (AHRS), uses an IMU to calculate the vehicle’s heading attitude relative to magnetic north. Data collected from the IMU sensors allows computers to track the aircraft’s position using a method called dead reckoning.
In land vehicles, IMUs can be integrated into GPS-based car navigation systems or vehicle tracking systems, giving the system dead reckoning capabilities and the ability to collect as much information as possible about the vehicle’s current speed, turn rate, heading, inclination and acceleration. The accurate data with the vehicle’s wheel speed sensor output as well as the reverse gear signal (if available) are used for better purpose traffic collision analysis.
In addition to navigation purposes, IMUs are used as orientation sensors in many consumer products. Almost all smartphones and tablets contain an IMU as an orientation sensor. Fitness trackers and other wearable devices may also contain IMUs to measure movement, such as running. The IMU is also able to determine an individual’s developmental level while exercising by identifying the specificity and sensitivity of specific parameters related to running. Some gaming systems use IMUs to measure motion. Low-cost IMUs have fueled a boom in the consumer drone industry. They are also frequently used in sports technology (technical training) and animation applications. They are competing technologies for motion capture technology.
In a navigation system, data reported by the IMU is fed into a processor that calculates altitude, speed, and position. A typical implementation called a strapdown inertial system integrates the angular rate of a gyroscope to calculate angular position. It is fused with the gravity vector measured by the accelerometer in a Kalman filter to estimate the attitude. Attitude estimation is used to convert acceleration measurements into an inertial reference frame (hence the name inertial navigation), where they are integrated once to obtain linear velocity and twice to obtain linear position.
For example, if an IMU installed in an aircraft moving along a certain direction vector will measure the aircraft’s acceleration as 5 m/s2 for 1 second, after 1 second the guidance computer will infer that the aircraft must be flying at 5 m/s, and Must be 2.5 m from the initial position (such as a satellite or terrestrial radio transponder, although external sources are still used to correct for drift errors, and since the position inertial navigation system allows the update frequency to be higher than the smoothness of the vehicle motion can be perceived on the map display This method of navigation is used in conjunction with a system called GPS (because the navigation system position output is often used as a reference point to produce a moving map), the guidance system can use this method to show the pilot the aircraft’s geographical position at a certain moment in time. Like a moving map display.
A major disadvantage of using IMUs for navigation is that they are often affected by accumulated errors. Because the guidance system continuously integrates acceleration versus time to calculate velocity and position, any measurement error, no matter how small, accumulates over time. This results in “drift”: a growing discrepancy between where the system thinks it is and where it actually is. Due to integration, a constant error in acceleration results in a linear error growth in velocity and a quadratic error growth in position. A constant error in the attitude rate (gyro) results in a quadratic error growth in velocity and a cubic error growth in position.
IMU performance
There are many types of IMUs, depending on the application type, with performance ranges:
Gyroscope from 0.1°/s to 0.001°/h (angular velocity random walk)
Accelerometers from 100 mg to 10 µg (bias repeatability)
Roughly speaking, this means that for a single uncorrected accelerometer, the cheapest (100 mg) loses its ability to provide 50 meter accuracy after about 10 seconds, while the best accelerometer (10 mg) Lost the ability to provide 50 meter accuracy. µg) loses accuracy over 50 meters after approximately 17 minutes.
The accuracy of the inertial sensors within the inertial measurement unit (IMU) has a more complex impact on the performance of the inertial navigation system (INS).
The behavior of gyroscope and accelerometer sensors is usually represented by errors based on the following, assuming they have appropriate measurement range and bandwidth:
1.Offset error: This error can be divided into stability performance (the drift of the sensor under constant conditions) and repeatability (the error between two measurements under similar conditions, but with different intermediate conditions).
2.Scale factor error: First-order sensitivity error due to non-repeatability and nonlinearity.
3.Misalignment error: due to imperfect mechanical installation.
4.Noise: Depends on required dynamic performance.
5.Environmental sensitivity: mainly sensitivity to thermal gradients and acceleration.
All of these errors depend on various physical phenomena unique to each sensor technology. Depending on the target application and to be able to make the right sensor selection, it is important to consider the needs in terms of short- and long-term stability, repeatability, and environmental sensitivity (mainly thermal and mechanical environments). In most cases, the target performance of the application is better than the absolute performance of the sensor. However, sensor performance is repeatable over time, with more or less accuracy, so it can be evaluated and compensated to enhance its performance. This real-time performance enhancement is based on sensor and IMU models. The complexity of these models will then be chosen based on the performance required and the type of application being considered. The sensor and IMU models are calculated at the factory through a dedicated calibration sequence using a multi-axis turntable and a climate chamber. They can be calculated for each individual product or generally for the entire production. Calibration typically improves a sensor’s original performance by at least twenty years.
Assemble High-performance IMUs or IMUs designed to operate in harsh conditions are often suspended by shock absorbers. These shock absorbers need to master three effects: 1.Reduce sensor errors due to mechanical environmental requirements. 2.Protect sensors as they may be damaged by shock or vibration. 3.Contain spurious IMU motion within a limited bandwidth that processing will be able to compensate for.
Reducing these errors often prompts IMU designers to increase processing frequencies, and this is made easier with the latest digital technology. However, developing algorithms that can eliminate these errors requires deep inertial knowledge and a close understanding of sensor/IMU design. On the other hand, if suspension has the potential to improve IMU performance, it will have side effects on size and mass. The ER-MIMU01 product developed by Ericco uses a three-axis gyroscope and a three-axis accelerometer. Below are the important parameters of the gyroscope and accelerometer added to the ER-MIMU01 model IMU:
As one of the products of inertial sensor,quartz accelerometersare the basic measurement element of inertial navigation and inertial guidance system, and their speed and position are obtained by integrating the acceleration. They work on the basis of Newton’s second law, which state that the resultant force on an object is equal to its mass times its acceleration. Therefore, the performance and accuracy of the accelerometer directly affect the accuracy of the navigation and guidance system, and we will briefly understand its advantages and disadvantages.
The advantages of quartz accelerometers
High precision and sensitive
The quartz accelerometer uses digital signal processing technology, the reaction speed is very fast, and it can respond to acceleration changes in an instant. At the same time, it has the characteristics of high precision and high sensitivity. It can accurately measure the acceleration change of the object during the movement and output it as a digital signal. This feature of high precision and high sensitivity. For example, the zero-bias stability of ER-QA-03A is 10-50μg, the scale factor is 15-50 PPM, and the second-order nonlinearity is 10-30μg/g2, which provides accurate data support in the industrial field to help engineers perform accurate motion control and analysis.
Small size and light weight
In the case of limited carrier space design size, this allows small quartz accelerometers to be conveniently installed in a variety of equipment and structures without placing too much burden on them. The small size and light weight also mean that acceleration sensors can operate in limited Spaces and have high reliability. The ER-QA-03Fis a small accelerometer with a diameter of Φ18.2mm, a scale factor of 150-220 PPM, and a second-order nonlinearity of 40-50μg/g2. Compared with products with the same parameters, this accelerometer is a good choice for equipment that can meet the requirements of relevant parameters and meet the strict requirements of space.
Strong ability to adapt to temperature
Quartz accelerometers have a wide operating temperature range. Whether it is in an extremely cold environment or in a high temperature environment, it can work normally. This makes its application in extreme conditions possible. Such as aerospace, deep sea exploration and oil and gas drilling fields. ER-QA-03D can operate normally at a working temperature of -55~180 ° C, and its volume of 25×21mm, impact resistance 500-1000g 0.5ms. The acceleration sensor has the function of self-diagnosis and fault detection. With internal algorithms and automatic calibration, the accelerometer detects and corrects its own faults, ensuring data accuracy and reliability. This self-diagnosis and fault detection capability helps reduce maintenance costs and increase productivity.
The Disadvantages of quartz accelerometers
Temperature effect
In the long-term high temperature environment, the working accuracy of the quartz accelerometer will be affected by the temperature, because the crystal lattice structure changes will lead to changes in the resonant frequency, so the temperature needs to be compensated or used in the appropriate temperature range.
Complex structure
The structure of quartz vibration beam accelerometer is relatively complex, and the manufacturing process requires a high level of technology, so the cost is high.
High cost
The manufacturing and maintenance cost of inertial navigation and positioning system is high, requiring the use of precision instruments to manufacture and debug, and the maintenance cycle is short and the maintenance cost is high.
This paper introduces the advantages of quartz accelerometer such as high precision, high sensitivity, temperature influence, complex structure and high cost, but with the development of quartz accelerometer technology, these disadvantages can be further optimized.
text link:https://www.ericcointernational.com/application/what-are-the-advantages-and-disadvantages-of-quartz-accelerometers.html
A drone is an aircraft that does not require human piloting. It is equipped with various sensors and control systems and can perform tasks autonomously. The main role of the IMU is attitude control and flight stability. Based on purpose and design features, drones can be divided into the following three types:
✮Fixed wing drone
✮Multi-rotor drone
✮Vertical take-off and landing and transition drone
1. Fixed-wing UAV: The design of this UAV is similar to a traditional aircraft, with fixed wings and tail. It is usually used for long-duration flights and wide-area reconnaissance missions, with high speed and the ability to maintain flight stability. For example, the ER-MIMU02 and ER-MIMU06 developed by Ericco can be used in fixed-wing UAVs to perform the initial alignment of the UAV launch system. The machine performs attitude control.
Product advantages: The bias stability of the gyroscope is reduced to 0.5 degrees per hour. This accuracy level has reached that of MEMS sensors. limit value.
2.Multi-rotor UAV: This type of UAV provides lift and control force through multiple rotors, the most common ones are four-rotor and six-rotor. Multi-rotor drones have vertical take-off and landing and hovering capabilities, and are suitable for tasks such as close-range reconnaissance, aerial photography, and logistics distribution. For example, the ER-MIMU03 and ER-MIMU07 developed by Ericco can be used in multi-rotor drones. These products have built-in acceleration sensors and gyroscopes, which can measure linear acceleration and rotational angular velocity in three directions, and obtain the attitude and speed of the carrier through analysis. and displacement information for precise positioning.
Product advantages: The bias stability of the gyroscope is reduced to 3 degrees per hour. The drone can be well controlled for positioning.
3. Vertical take-off and landing and transition drone: This kind of drone has a variable flight mode and can switch between vertical take-off and landing and horizontal flight. It combines the advantages of fixed-wing UAVs and multi-rotor UAVs, and is suitable for tasks requiring long-term flight and flexible maneuverability. The IMU plays a key role in vertical takeoff and landing and transition drones, and can be used for flight mode conversion. For example, the ER-MIMU04 and ER-MIMU08 developed by Ericco can be used for vertical take-off and landing and transition drones, and can switch flight postures at will.
IMU is not only an important part of the above three types of drones, but also plays an important role in the IMU pod. On the pod, the IMU’s main role is to provide stable images and image transmission. In addition to its two main functions of attitude control and flight stability, it can also be used with other sensors such as GPS (Global Positioning System) and magnetometer to provide more accurate navigation and positioning information.
IMU provides key data for the control and navigation of drones in the field of drone applications, allowing drones to efficiently perform various tasks. Different types of UAVs have different IMU applications depending on their design and purpose, but whether they are fixed-wing, multi-rotor or vertical take-off and landing and transition UAVs, IMU is used to realize their flight control and A key component of navigation.
If you want to learn about or purchase IMU products, please contact us in time.
Tilt sensoris a sensor used to measure the tilt angle of an object relative to the horizontal plane. It can accurately and real-time monitor and record the change of tilt angle, which provides important data support for various industrial applications and scientific research fields.
1. Bridge monitoring
Bridges are an important part of urban traffic, and their stability and safety are crucial to the normal operation of the city. In order to ensure the safety of the bridge, it is necessary to monitor its structure in real time. Tilt sensor can be used to monitor the tilt angle of bridge and provide real-time data support for structural safety. By installing tilt sensors at key parts of the bridge, the tilt angle can be continuously monitored and the data can be transmitted to the control center for analysis. Once abnormal conditions are found, timely measures can be taken for maintenance and reinforcement, thus ensuring the safe use of the bridge. For example, ER-TS-3160VO can be installed in the key part of the bridge to monitor the change of the tilt angle of the bridge, its accuracy is 0.01°, the measurement range is 0~±180°, and the measured value can be output by 0~10V, 0.5~4.5V, 0~5V voltage, which is very suitable for bridge, dam and other monitoring projects.
2. Construction machinery
Excavator — In order to realize the three-dimensional spatial positioning of the excavator, on the basis of installing the angle sensors of each joint of the working device, the platform rotation angle detection device and the platform inclination sensor are installed, and the laser receiver is installed on the bucket rod to detect the height of the horizontal mechanism emitted by the ground laser transmitter relative to the zero position of the receiver. The kinematics model of the excavator is established, and the coordinate transformation matrix of the car body relative to the earth is derived, that is, the car body positioning in three-dimensional space is completed, and the commonly used simple car body elevation positioning formula is obtained, so as to realize the three-dimensional space positioning of the excavator’s excavation trajectory and lay the foundation for realizing the accuracy of the excavator’s three-dimensional space trajectory and the excavator’s depth control.
Other heavy industrial machinery – in addition to excavators, in other heavy industrial machinery, including cranes, lifts, graders, etc., will use tilt sensors, and tilt sensors have a heavy and heavy role in these heavy machinery equipment. It not only ensures that the angle range of these mechanical equipment is within the safety, but also can be raised to the alarm if it is out of range to protect personal safety. For example, the tilt sensor in the retractable robot arm is used to measure the attitude of the cab and the change of the tilt angle of the boom to ensure driving safety. ER-TS-4258CU has strong resistance to external electromagnetic interference and is suitable for long-term work in harsh industrial environments. It can be installed in the retractable arm of the construction machinery, and can measure the attitude of the cab and the tilt angle of the boom in real time, which can ensure the driving safety to the greatest extent.
3. Platform control
Shipborne horizontal platform – The inclination sensor is applied on the shipborne horizontal platform, which is used for shipborne satellite to track the base of the antenna to keep the antenna in a horizontal state at all times, and for real-time control of the platform, which can isolate the pitch and roll motion of the hull and make the platform level.
In addition, the inclination sensor is also applied in the launching process of the ship air bag, and is applied to the hook swing of the large pipe laying ship for monitoring and adjustment.
Application of inclination sensor in automatic levelling system of reference plane of large optoelectronic equipment. The dip angle sensor installed on the base detects the dip angle and direction of the reference plane, converts the angle into the elongation of several mechanical legs according to the leveling algorithm, and drives the elongation of the mechanical legs to make the reference plane level.
