In the article on the accuracy of tilt sensors, we discussed in detail the factors that affect the accuracy of tilt sensors and methods to improve their accuracy. This article will mainly explore the concept of resolution of tilt sensors and describe the relationship between resolution and accuracy.
Resolution refers to the minimum change value that a sensor can detect and distinguish within its measurement range. And accuracy refers to the error between the angle measured by the sensor and the true angle.
Take the familiar vernier caliper as an example. We often say that the accuracy of a vernier caliper is 0.1mm, but this statement is incorrect. It should be said that the resolution of a vernier caliper is 0.1mm. That is to say, when the change in length is 0.1mm, can our eyes detect and distinguish it. The accuracy of a vernier caliper is related to many factors, as it represents the difference between the measured value and the true value. For example, temperature can cause thermal expansion and contraction. When we see a change of 0.1mm, it may actually be 0.09mm. For example, if the caliper is bent or the markings on the caliper are not particularly uniform, it can lead to a decrease in accuracy, but the resolution is still 0.1mm. To improve the accuracy of measurement, the first step is to increase the resolution of the measurement. If the resolution cannot be resolved, then how can the accuracy be discussed. Resolution is the limit of accuracy, and improving resolution requires eliminating the influence of other factors on accuracy in order to effectively improve the final accuracy.
Using the acceleration principle of a tilt sensor as an example, provide a detailed explanation. It measures the component of gravity acceleration on the sensitive axis of the accelerometer and converts it into angle data, that is, the inclination value and acceleration value have a sine relationship. This principle has been fully explained in many literature and product descriptions. The resolution of a tilt sensor is often referred to as sensitivity. It is mainly caused by sensor noise. We call the angle resolution the equivalent angle change of noise. Because the magnitude of noise is related to frequency response, the higher the frequency response, the greater the noise. Taking effective measures to suppress noise can effectively improve the resolution of sensors. After increasing the resolution, there is a chance to compensate for the adverse effects of other factors on accuracy.
There are many factors that affect the accuracy of tilt sensors, including resolution and:
Zero bias - depending on the inherent characteristics of the core sensitive device, it refers to the sensor measuring an output that is not zero in the absence of angle input (such as absolute horizontal plane), and the actual output angle value is called zero bias.
Nonlinear - can be corrected through subsequent calibration, depending on the number of calibration points. The more correction points there are, the better the nonlinearity.
Horizontal axis error refers to the error generated when a sensor is coupled to its output signal when a certain acceleration or tilt angle is applied perpendicular to its sensitive axis direction.
Input axis misalignment refers to the installation deviation of sensors during actual installation, which actually includes errors in input axis misalignment and vertical axis misalignment.
Of course, it also includes some other factors. The impact of all these factors is described in detail in the article on the accuracy of the tilt sensor. This article will not elaborate further.
Appendix 1
The core technological advantages of Huilian Technology's tilt sensor
Huilian Technology's tilt sensor has excellent angle measurement performance, creatively incorporating horizontal axis error and zero offset as important components of measurement accuracy. (Note: Other general tilt sensor products only consider nonlinearity as the measurement accuracy of the sensor). The Huilian tilt angle sensor combines the "horizontal axis error" with the "allowable input axis non coincidence degree", greatly solving the problem of achieving truly accurate tilt measurement at any angle point:
1. The actual tilt of an object cannot occur completely along the strict X and Y orthogonal axes, as factors such as the clearance of mechanical components and the difficulty in determining the actual tilt axis determine that the actual tilt angle is not in the strict X and Y orthogonal directions. When there is a tilt in the X-axis direction, if the horizontal axis error of the sensor is too large, it will cause a change in the tilt angle data in the Y-axis direction, but in reality, the Y-axis direction may not have truly tilted, and vice versa. Therefore, even if the linearity is high, the actual measurement accuracy of an ordinary tilt sensor with a horizontal axis error of 3-5% will still be around 3-5%, rather than linearity data.
2. If the sensor does not have "allowable input axis misalignment" data during actual installation, it is difficult to obtain truly accurate tilt data through simple visual inspection. Excessive deviation angle between the sensitive axis of the sensor and the actual tilt direction of motion will result in an additional "sine error" being added to the output data of the sensor. As the tilt angle increases, the error also gradually increases.
3. Truly achieve full angle range measurement. The Huilian tilt sensor does not have a significant increase in+-90 degree error, and can achieve accurate measurement in all directions and attitudes. High accuracy and good consistency throughout the entire measurement range.
4. Implement dynamic compensation for the tilt sensor to reduce the impact of external acceleration on measurement, without reducing the measurement frequency response, while achieving high-speed and high-precision measurement.
The inclination sensor of Huilian Company has effectively solved the above practical problems and is a product that truly achieves high-precision inclination measurement.
Introduction to Huilian's core technical capabilities in inclination measurement
1. Modal testing of the inclination sensor housing is not simply about installing the sensor core components in any housing and packaging them into a product.
2. Perform modal testing on the tilt sensor PCBA board to fundamentally address the impact of resonance caused by vibration on sensor filtering.
3. Tilt angle sensors that are tested strictly in accordance with relevant domestic and international standards, including GB, GJB, MIL, IEC, ISO, EN, etc.
4. Multiple invention patents, utility model patents, appearance patents, and software copyrights in the field of inclination measurement.
5. An automated testing technology tilt sensor with independent patents reduces the impact of human factors on quality and maintains consistency in quality.
6. The accuracy can reach a comprehensive accuracy of ± 5 arcseconds @ -40~85 ℃ at all temperatures, and the zero stability over 12 months can reach ± 3.6 arcseconds. We can provide the world's most accurate tilt sensor and are still improving it.
7. We have core research and development capabilities, including three PhDs and five masters, and can customize tilt measurement products for customers with special requirements.
