Research On Fast Positioning Of Unexploded Ordnance Based On Simplified HAP Algorithm

Unexploded ordnances refer to ordnances left behind after wars or other military activities,which remain unexploded.These ammunitions pose a great threat to the safety of human life and property.The UXO cleanup problem has three stages: detection,inversion,and classification.And the most important part is the inversion,which requires recovering a set of parameters that specify a physics-based model representing the object under interrogation to be used as inputs to the classifier of choice.Among the many parameters,the inversion of the position of the target is the most critical,so the traditional HAP algorithm is simplified in this paper to achieve the rapid positioning of the unexploded ordnances.The traditional HAP algorithm assumes the target exhibits a dipolar response and requires only three global values: a magnetic field vector H,a vector potential A and a scalar magnetic potential ,all at a single location in space.Among these values,only the scattered magnetic field,H,is measurable with current electromagnetic induction sensors.Therefore,in order to estimate the scattered magnetic scalar and vector potentials from data,a numerical technique called the method of auxiliary sources(MAS)is employed according to Huygens' s principle.Through simulation calculations,it is found that the vector potential A equivalent by the traditional HAP algorithm has a large error,so this paper will use a simplified HAP algorithm,that is,only two quantities of H and can be used to obtain the position information of the unexploded ordnances.Secondly,the six parameters affecting the simplified HAP algorithm are studied one by one.The results show that when the z component of the dipole moment is zero,the auxiliary plane size is set to be the same as the measurement plane size,the twodimensional dipole distribution is the same as the measurement point,the auxiliary surface height is selected as 0.2m,the horizontal position of the dipole is near the center of the measurement plane and the depth does not exceed 1m,the simplified HAP algorithm can quickly achieve accurate dipole positioning.But when the z component of the dipole moment is not zero and the dipole depth is less than 60 cm,the inversion accuracy is high.When the depth is greater than 60 cm,the error gradually increases with the increase of the depth.Finally,using the transient electromagnetic detection system independently developed by the laboratory,three-component response tests of the vertical and parallel main axes were performed on the four targets.Select appropriate parameters under each test condition,extract the magnetic standard position ,and perform a linear matrix operation on the measured three-component response and the extracted .When the target depth is about 50 cm and the excitation is perpendicular to the main axis,The horizontal error of the performance is within 2cm,and the depth error is within 3cm.When the target is about 50 cm in depth and the excitation is parallel to the main axis,the reversed horizontal error is within 2cm and the depth error is within 6cm.