Tan Wei, Loeb Gerald E
A. E. Mann Institute, Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
IEEE Trans Neural Syst Rehabil Eng. 2007 Jun;15(2):295-309. doi: 10.1109/TNSRE.2007.897028.
A bionic neuron (BION) is an inductively powered, miniature implant developed for functional electric stimulation (FES) to reanimate paralyzed limbs. This paper investigates the possibility of reusing the BION antenna coil as a magnetic sensor to provide meaningful posture information for feedback control of FES. A variety of techniques have been developed to model and cancel nonideal effects caused by the shapes of the internal and external coils, ferrite material, and electronic connections. Field warping has been employed to both amplitude and direction to achieve more accurate description of the dipole magnetic field generated by external coils suitable for generating a reference magnetic frame in the environment of a wheelchair. Models of the transmitting coil and the receiving BION coil were validated against experimental data, providing a solid foundation for implementing a sensor system. Based on the established model, a magnetic sensing system combined with customized microelectro-mechanical systems (MEMS) accelerometer has been designed and tested as a prototype on the bench. The sensor output can be employed to compute 6-D position and orientation. A two-step algorithm integrated with multiple error-cancelling techniques demonstrated sufficient accuracy in bench tests to appear promising for control of reach-and-grasp tasks. A sensor fusion step is proposed to estimate the position and orientation of a limb segment using data from multiple implants in muscles, where they will also function as neuromuscular stimulators to produce the movements to be controlled.
仿生神经元（BION）是一种通过感应供电的微型植入装置，专为功能性电刺激（FES）而开发，用于使瘫痪肢体恢复活动能力。本文研究了将BION天线线圈重新用作磁传感器，为FES的反馈控制提供有意义的姿势信息的可能性。已经开发了多种技术来对由内部和外部线圈形状、铁氧体材料以及电子连接所引起的非理想效应进行建模和消除。场扭曲已应用于幅度和方向，以更准确地描述由外部线圈产生的偶极磁场，该磁场适用于在轮椅环境中生成参考磁框架。针对实验数据对发射线圈和接收BION线圈的模型进行了验证，为实现传感器系统奠定了坚实基础。基于所建立的模型，设计了一种结合定制微机电系统（MEMS）加速度计的磁传感系统，并在实验台上作为原型进行了测试。传感器输出可用于计算六维位置和方向。一种集成了多种误差消除技术的两步算法在实验台测试中显示出足够的精度，有望用于控制抓握任务。提出了一种传感器融合步骤，利用来自肌肉中多个植入物的数据来估计肢体节段的位置和方向，在这些植入物中它们还将作为神经肌肉刺激器来产生待控制的运动。
