Six-Axis Accelerometer Based On Parallel Platform

Applying in manipulator to realize dynamic and stable grasping, six-axis accelerometer is a kind of inertial sensors getting kinetic parameters in the field of robots. Based on a few researches on six-axis accelerometer at home and abroad, this thesis presented a method of designing six-axis accelerometer using Stewart platform as the structure of sensor and researched on theory. The physical model of solution space on the structure of six-axis accelerometer with nondimensional parameters was established and changed into 2D plane by the conversion formulas. In order to research performance indexes, mathematics model of structure was given under the coordinates system attached to lower-platform. Acceleration Jacobian matrix was detailedly deduced through the method of vector product, and by the condition number of Jacobian matrix, the acceleration and angle acceleration isotropy indexes were defined and deduced analytic expression basing on nondimensional parameters of structure. What's more, the relation of isotropy of the sensor and structural parameters was analyzed on the performance atlases. Deducing sensitivity Jacobian matrix of six-axis accelerometer and relying on the singular value and condition number of the matrix, this thesis gave the definition of acceleration and angle acceleration performance indexes: minimal sensitivity index, sensitivity isotropy index and total sensitivity index. Meanwhile, analytic expression of these performance indexes were calculated. At last the relations of structural parameters and sensitivity of the sensor were analyzed through observing performance atlases of sensitivity. According to deduced coordinate transformation matrix of acceleration and angle acceleration, how translation and rotation of the coordinates system affected isotropy and sensitivity of the sensor was analyzed in detail in the thesis. And by comparing atlases under the coordinates attached to the upper-platform with those under the coordinates attached to lower-platform, the affection was visually expressed. Based on observing atlases and calculation, the values of structural parameters were given in the end of the thesis.