A novel method of measuring spatial rotation angle using MEMS tilt sensors

This paper presents a novel method of measuring spatial rotation angle with a dual-axis micro-electro-mechanical systems tilt sensor. When the sensor is randomly mounted on the surface of the rotating object, there are three unpredictable and unknown mounting position parameters: α , the sensor's swing angle on the measuring plane; β , the angle between the rotation axis and the horizontal plane; and γ , the angle between the measuring plane and the rotation axis. Thus, the sensor's spatial rotation model is established to describe the relationship between the measuring axis, rotation axis, and horizontal plane, and the corresponding analytical equations are derived. Furthermore, to eliminate the deviation caused by the uncertain direction of the rotation axis, an extra perpendicularly mounted, single-axis tilt sensor is combined with the dual-axis tilt sensor, forming a three-axis tilt sensor. Then, by measuring the sensors' three tilts and solving the model's equations, the object's spatial rotation angle is obtained. Finally, experimental results show that the developed tilt sensor is capable of measuring spatial rotation angle in the range of  ±180° with an accuracy of 0.2° if the angle between the rotation axis and the horizontal plane is less than 75°. (paper)