Herein by the electronic components Encyclopedia sharing, an acceleration sensor capable of measuring acceleration in the respective directions, whereby the inclination angle can be calculated, which in the car, and the wearable device into industrial systems have wide applications.
What design features axis acceleration sensor is?
When the uniaxial acceleration sensor for detecting a tilt angle, the detection axis of a plane perpendicular to gravity, or parallel to the plane of gravity?
Uniaxial acceleration sensor may be used in relatively simple applications, such as a simple finite angle of tilt angle sensor. Vehicle inclination angle detection exemplified, in order to prevent side slip and overturned, the car will generally use a sensor to detect acceleration of the inclination angle of the vehicle. At this time, the detection axes should be perpendicular to the plane of gravity. Because the detection axis and a plane perpendicular to gravity, acceleration sensors for small angle changes relatively high sensitivity, while the car is generally not too large angle of inclination. Below we compare the difference between these two ways of installation.
Below, the slope angle θ. The left figure, the detection axis of the X-axis plane perpendicular to gravity (slope is zero), the output of the acceleration sensor case Ax = sin (θ) * 1g. FIG lower right Z axis is parallel to the detection plane of gravity (slope is zero), the output of the acceleration sensor at this time Az = cos (θ) * 1g.
We focus on two ways to put a map. To compare the two methods, the acceleration sensor output change. Below, the length of the red line, corresponding to a plane perpendicular to the gravitational force, the output of the detection axis of the acceleration sensor. When the length of the green line segment, corresponding to the detection axis is parallel to the plane of gravity, the output of the acceleration sensor.
It can be seen that when θ from 0 ° to 30 ° change significantly change the red line and the green line becomes insignificant. As can be seen in the inclination angle of the small angle changes, the detection axis perpendicular to the mounting plane of gravity, a higher sensitivity is obtained. The real world, the vast majority of ramp slope on the road no more than 30 °. Therefore, the tilt angle detecting auto embodiment, if a single-axis acceleration sensor is provided to detect the axial direction perpendicular to the planar direction of gravity appropriate. Of course, if the inclination angle is in the range of 60 ° to 90 °, and the inclination angle of the acceleration sensor due to the relationship sin ([theta]) function, change in angle of the acceleration sensor sensitivity is lowered.
Depending on the application requirements of how to calculate the minimum sensitivity uniaxial acceleration sensor?
It assumed that the actual inclination angle detection applications range between -63 ° to + 63 °, and the detection result is accurate to 1 °. First, the introduction of the incremental sensitivity generous concept, each increment is equal to the output sensitivity stepping increment corresponding to the inclination angle, the unit displayed in mg. S [g] = 1g * (sin (θ + P) -sin (θ)), (θ for the current angle, P is the step size), incremental changes in sensitivity of the response output magnitude. Setting the inclination angle θ is X, the corresponding increment sensitivity S [g] plotted as Y, we obtain:
In order to meet the requirements of the application in the entire range of the tilt angle detection resolution, the minimum sensitivity of the system may be determined using the curve of FIG. Assume that the application requires a minimum resolution of 1 °, the inclination angle detection range between -63 ° to + 63 °. According to the figure, the inclination angle increment sensitivity 0 ° to 90 ° change gradually becomes smaller, when it reaches 63 °, the sensitivity down to 4.074mg / 1 °. For digital output of the acceleration sensor, the sensitivity is generally used LSB / g expressed. LSB they are the least significant bits, g is the gravitational acceleration. Each LSB to distinguish between 4.074mg output,
Then the corresponding minimum sensitivity is 246LSB / g (1g / 4.074mg). When selecting an acceleration sensor, the sensitivity should ensure minimum sensitivity of the acceleration sensor is larger than the computed value.
These are what design features single-axis acceleration sensor is? I hope you have help.