Fusion Positioning of Mobile Equipment in Underground Coal Mine Based on Redundant IMUs and UWB

Current positioning methods for indoor or outdoor robots show poor applicability and limited performance for underground mobile equipment with complex scene interference, such as narrow roadways, heavy dust, and poor illumination. Therefore, a fusion positioning framework is proposed based on redundant inertial measurement units (IMUs) and ultra-wideband (UWB) by using a factor graph (FG). In this framework, six layout models of redundant IMUs are designed and compared to fundamentally inhibit the accumulation of positioning errors to a large extent. Then, the optimal layout parameters of base stations are explored through many simulation experiments in terms of the number, shape, and height to preliminarily improve the positioning accuracy of the UWB system. A hybrid calculation method based on bacterial foraging optimization algorithm and Taylor is provided to further enhance the positioning accuracy of UWB in a complex environment. Subsequently, the UWB credibility factor is developed to dynamically adjust the fusion weight of UWB information, to weaken the influence of the non-line of sight errors. Furthermore, FG architecture integrated with the UWB credibility factor is applied to fuse redundant IMUs and UWB for accurate positioning. Some simulations and experiments are carried out and the comparison results verify the superiority and practicability of the proposed positioning method for underground equipment.