在计算机辅助手术(CAS)中，需对深入病人体内的手术器械进行定位。为避免光学定位(OPT)中视线(LOS)限制的问题，目前多采用磁定位(MT)技术。提出一种新的多磁偶极子模型，旨在克服磁定位系统中，圆柱形永磁体的单磁偶极子近似模型不准确，所导致的定位范围减小、定位精度降低的问题。该模型将圆柱形磁偶极子等效为一组沿磁体轴线排布的多个点磁偶极子，并通过自适应粒子群优化算法(APSO)对定位结果解算。相比于经典模型，该模型能够保证自身在磁体近场区域的有效性。实验表明，较传统方法，位置定位误差可减小15.5%~31.6%，姿态估计误差可减小10.5%~24.4%。

In computer-assisted surgery (CAS), the surgical instruments in patient need to locate. To avoid the line of sight (LOS) problem in the optical tracking (OPT), magnetic tracking (MT) technology is usually adopted. A new multi- dipole model of cylindrical magnets, which can avoid limited tracking range and lower tracking accuracy problems that appear in signal magnetic dipole model of cylindrical permanent magnet, is proposed. This model approximates cylindrical magnetic dipole as multiple dipoles ranging along the magnet′s axis, and tracking results are obtained through adaptive particle swarm optimization (APSO). Compared with classical method, the proposed model can ensure its validity in near magnets region. Experiments show that, the solution can decrease positioning error by 15.5%~31.6%, and decrease orientation error by 10.5%~24.4%.