用有限元建模与多传感器融合,实现胶囊机器人的精准俯仰控制。
Pitch Angle Control of a Magnetically Actuated Capsule Robot with Nonlinear FEA-based MPC and EKF Multisensory Fusion
- 基于有限元仿真构建非线性动力学模型,嵌入查找表用于实时控制。
- 实验中俯仰调节速度比传统方法快3至5倍,振荡更小。
- 融合惯性与间歇视觉信息,支持低频成像下的稳定闭环控制。
磁控胶囊机器人有望实现胃肠道的微创诊疗,但现有系统普遍忽略对胶囊俯仰角的控制,而该自由度对接触式操作倾斜胃壁至关重要。本文提出一种非线性、基于模型的磁控俯仰控制框架,采用四线圈电磁阵列驱动可吞咽胶囊机器人。通过三维有限元分析(FEA)表征嵌入永磁体所受的角度依赖磁力与力矩,并将其以查表形式嵌入考虑滚动接触与执行器动态的刚体俯仰模型中。设计了带约束的模型预测控制器(MPC),在满足硬件电流与变化率限制条件下调节俯仰角。在仿胃表面实验中,无论初始水平或直立状态,均实现鲁棒俯仰重定向,相比开关控制,收敛速度提升约3至5倍,且振荡显著减少。此外,结合惯性测量与间歇视觉观测的扩展卡尔曼滤波(EKF),使相机更新率从30 Hz降至1 Hz时仍能保持稳定闭环控制,模拟临床成像限制条件。结果表明,基于有限元的模型预测控制与传感器融合是一种可扩展的俯仰调控策略,适用于精确对接与未来多自由度胶囊运动控制。
原文摘要 · Abstract (English)
Magnetically actuated capsule robots promise minimally invasive diagnosis and therapy in the gastrointestinal (GI) tract, but existing systems largely neglect control of capsule pitch, a degree of freedom critical for contact-rich interaction with inclined gastric walls. This paper presents a nonlinear, model-based framework for magnetic pitch control of an ingestible capsule robot actuated by a four-coil electromagnetic array. Angle-dependent magnetic forces and torques acting on embedded permanent magnets are characterized using three-dimensional finite-element simulations and embedded as lookup tables in a control-oriented rigid-body pitching model with rolling contact and actuator dynamics. A constrained model predictive controller (MPC) is designed to regulate pitch while respecting hardware-imposed current and slew-rate limits. Experiments on a compliant stomach-inspired surface demonstrate robust pitch reorientation from both horizontal and upright configurations, achieving about three to five times faster settling and reduced oscillatory motion than on-off control. Furthermore, an extended Kalman filter (EKF) fusing inertial sensing with intermittent visual measurements enables stable closed-loop control when the camera update rate is reduced from 30 Hz to 1 Hz, emulating clinically realistic imaging constraints. These results establish finite-element-informed MPC with sensor fusion as a scalable strategy for pitch regulation, controlled docking, and future multi-degree-of-freedom capsule locomotion.
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