Measuring inclination angle of Semi-crawler tractors using MEMS sensor

In this study, we established a method to calculate inclination angle of moving vehicles from acceleration and angular velocity measured by microelectromechanical systems (MEMS) sensor, which is becoming popular recently due to its ultra-small size and low manufacturing cost. We applied the technique to measure inclination angle of semi-crawler tractor to validate its usefulness. Results from various methods to calculate inclination angle of a vehicle from acceleration and angular velocity data showed that moving average acceleration method and wavelet acceleration method produced results that significantly deviated from the actual inclination angle, while results from angular velocity method and acceleration-angular velocity method were close to the actual inclination angle. Inclination angle calculated by acceleration method in a static state was very similar to the measurement from inclination sensor and was highly accurate, but did not demonstrate sufficient accuracy in dynamic state as the estimated inclination angle was at maximum 10' smaller at inclination angle of 75". In the meanwhile, the inclination angle calculated by angular velocity method showed only small deviation from the sensor measurement even at dynamic state. As a result of measuring inclination of semi-crawler type tractor using MEMS sensor, it was determined that the angular velocity method is the most versatile of the four methods tested as it can not only produce very accurate time series of inclination angle but also be used to easily obtain angular displacement from the angular velocity data obtained. However, error of integration was shown to increase with longer measurement times and it must be addressed by an appropriate solution. Acceleration-angular velocity method also produced similar results as experiments were performed indoors where disturbance factors were few. The inclination angle measurement system using MEMS sensor established in this study can be applied to agricultural vehicles such as tractors as well as to almost all construction and general vehicles with drive system. We expect the system to contribute to development of a safety system that can prevent rollover accidents and quickly respond to them.