An Error Correction Method for a 2-DoF Pointing Mechanism

The 2-DoF pointing mechanism is widely used in astronautics area to solve several key problems such as space orientation, infrared tracking, photoelectric collimation and missile guidance. As the most important performance parameter, the pointing accuracy directly decide the performance of the pointing mechanism. Most 2-DoF pointing mechanisms usually ensure their pointing accuracy by improving machining accuracy and optimizing assembly technology, which may bring substantial costs. Hence, an error correction method for 2-DoF pointing mechanisms is proposed in this paper. Firstly, the rotation deviation errors are defined in the kinematic model of 2-DoF pointing mechanism; Then a statically indeterminate equation set is constructed with the rotation deviation errors and the results of accuracy test. Lastly, the fixed errors (i.e., mainly the machining errors and the assembly errors) existing in the mechanism can be figured out by solving the indeterminate equation set. With the proposed method, the average pointing error of a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2-\text{DoF}$</tex> pointing mechanism decrease from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{0. 0 9 9 5}^{\circ}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{0. 0 1 8 4}^{\circ}$</tex>, while the maximum pointing error decrease from 0.1304° to 0.0375°.