Application knowledge of MEMS sensors in the hotte

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Large inventory of application knowledge of MEMS sensors in the automotive field

nowadays, people pay more and more attention to the preventive safety of automobiles. MEMS sensors are used in many fields of automotive safety technology. The following is a review of a number of application knowledge of MEMS sensors in the automotive field:

I Electronic stability control system (ESC)

electronic stability control system (ESC, electric stability control) is a device used to prevent vehicles from sideslipping on wet roads or curved roads after rain. The device uses Murata Electronics2. The impact strength test range is different: oy (hereinafter referred to as MFI) acceleration sensor

generally, ABS and traction control system alone cannot meet the driving safety requirements of vehicles on curved roads. In this case, the electronic stability control system (ESC) can control the vehicle not to deviate from the road by correcting the understeer or oversteer in the driver's operation. The system uses a gyroscope to measure the yaw angle of the vehicle and a low gravity acceleration sensor to measure the lateral acceleration. Compare the measured data with the results calculated from the driving speed and wheel inclination angle, so as to adjust the vehicle steering to prevent side slip

acceleration sensors are usually installed independently near the center of gravity of the vehicle, or installed on the printed circuit board as a part of the sensor group in the form of mounting components. The standard measurement range is ± 1.5-2.0g; The offset is independent of temperature or service time, and is stable below 100mg; The frequency band is in the range of 0-50Hz

electronic stability control system (ESC) usually needs to take the transverse direction of the vehicle as the detection axis to ensure that the impact is controlled to a minimum when subjected to longitudinal acceleration or vehicle deceleration. When the acceleration sensor of MFI is installed on the printed circuit board, but the elastic modulus is low, two installation directions can be selected, that is, whether the detection axis is parallel or vertical to the installation surface. p>

worldwide, the formulation of standards and regulations related to ESC is being actively promoted. Under the framework of the "1998 agreement" of the United Nations "World Forum for harmonization of vehicle regulations", the global technical regulation (GTR) on "electronic stability control system for light vehicles" was formulated and approved by WP29 (i.e. gtr8) in 2008. Countries and regions including the United States, Europe and the United States, Japan, Australia, South Korea, etc. have or are using ESC as a mandatory safety device. As a signatory of the "1998 agreement", China has fully participated in the coordination process of ESC global technical regulations since 2007, and has put forward a number of proposals in combination with domestic ESC product development, application and testing capabilities, and is formulating relevant national standards

II. Electronic parking brake system (EPB)

epb (electronic parking brake) replaces the traditional parking brake device based on mechanical lever and chain, providing more effective parking assistance for drivers. And because the parking brake lever between the driver's seat and the passenger's seat is cancelled, the space around the driver's seat can be used more effectively. The EPB system can continuously adjust the braking force according to the longitudinal inclination of the vehicle body. Just press the corresponding button on the instrument panel, and the brake will be locked; When the vehicle starts and accelerates, the brake will unlock automatically

the system can also assist in controlling the vehicle under low-speed traction to prevent the vehicle from sliding naturally on the slope. After the system is connected with the signal of the distance sensor system, it can even complete parallel parking in a narrow area. If it is integrated with the engine anti-theft system, a set of the most reliable anti-theft mechanism can be formed

the actual measurement starting point of the sensor in the system is usually within ± 3 °; The corresponding gravitational acceleration value is about 50mg. This is just consistent with the offset stability requirements of the vehicle in the whole service life and temperature range. The frequency range of sensors inside the system shall be kept as low as possible as required, and the upper limit shall not exceed Hz

III. anti lock braking system (ABS)

in four-wheel drive vehicles, since each wheel may slip, the body speed and wheel speed parameters required by the ABS system cannot be measured by transmitting the existing market position sensor. Therefore, the acceleration/deceleration information of the vehicle can only be obtained by measuring the acceleration in the front and rear directions. The acceleration sensor of ABS system can be installed in the ABS Controller in the form of independent components or integrated on the printed circuit board, and can also be installed in other sensors

the measurement range of the acceleration sensor used by the ABS system is usually 1-2g (G is the gravitational acceleration). The error deviation can always be lower than 100mg within the detection temperature range and the service life of the vehicle. The direction of the detection axis of the sensor must be the front and rear direction of the vehicle. Murata electronics oy's acceleration sensor can meet the application of various sensor units and printed circuit board mounting

IV. electronic control suspension system (ECS)

the main purpose of electronic control suspension system (ECS) is to adjust the suspension system according to the driving speed, road conditions, steering conditions, transmission status and other information as well as different driving conditions, so as to provide good operating stability and riding comfort for drivers. ECS system presents users with a variety of driving experiences from smooth and comfortable to high-speed and pleasant. The driver can freely switch between sports, normal and comfortable driving modes by pressing the select button

the acceleration sensor inside the ECS system can be used to detect the motion state of the car body, and sometimes it can also be used to detect the motion state of the front wheel in the vertical direction. Two acceleration sensors used to detect the motion state of the car body are installed near the fixed point of the front shock absorber and the top of the spring. The acceleration sensor near the wheel hub is installed near the shock absorber and wheel spring. In this way, the vertical distance difference between the vehicle body and the wheel can be calculated from the measured data of the two groups of sensors. In the more advanced wheel hub sensor system, the acceleration sensor is replaced by the distance sensor, which is used to directly measure the distance between the wheel and the vehicle body

in addition, in many ECS systems, the middle or rear of the vehicle is additionally equipped with an acceleration sensor for detecting vehicle bumps. It can slightly eliminate the inclination of the car body during acceleration or deceleration

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