用折纸气动肌腱设计轻便膝康复外骨骼,结合深度库普曼模型实现精准实时控制。
Design and Koopman Model Predictive Control of A Soft Exoskeleton Based on Origami-Inspired Pneumatic Actuator for Knee Rehabilitation
- 基于折纸气动驱动器设计轻便可穿戴外骨骼,提升舒适性与安全性。
- 融合肌电与脉宽调制信号的深度库普曼模型显著提升人机交互建模精度。
- 个性化建模+模型预测控制优于传统PID,适合个体化康复训练场景。
针对中风导致的下肢功能障碍,传统刚性外骨骼存在重量大、穿戴困难及需额外柔顺控制的问题。相比之下,软外骨骼更易穿戴且具备内在柔性,但其复杂非线性的人机交互动力学给控制带来挑战。本文基于折纸启发的气动执行器,设计了一款轻便舒适的膝关节康复外骨骼。为保障控制性能并实现良好人机协同,首先利用深度库普曼网络建模人机交互动态,将肌电(EMG)信号与控制气阀和泵的脉宽调制(PWM)占空比作为输入,线性库普曼模型准确捕捉了复杂动态。在此基础上,基于所得库普曼模型采用模型预测控制(MPC)实现实时康复训练,目标是跟踪屏幕上设定的参考轨迹。实验表明,引入肌电信号显著提升了模型精度;基于个体数据训练的个性化库普曼模型优于通用模型。因此,该控制框架在被动与主动训练模式下均优于传统PID控制,为软康复机器人提供了一种新控制范式。
原文摘要 · Abstract (English)
Effective rehabilitation methods are essential for the recovery of lower limb dysfunction caused by stroke. Nowadays, robotic exoskeletons have shown great potentials in rehabilitation. Nevertheless, traditional rigid exoskeletons are usually heavy and need a lot of work to help the patients to put them on. Moreover, it also requires extra compliance control to guarantee the safety. In contrast, soft exoskeletons are easy and comfortable to wear and have intrinsic compliance, but their complex nonlinear human-robot interaction dynamics would pose significant challenges for control. In this work, based on the pneumatic actuators inspired by origami, we design a rehabilitation exoskeleton for knee that is easy and comfortable to wear. To guarantee the control performance and enable a nice human-robot interaction, we first use Deep Koopman Network to model the human-robot interaction dynamics. In particular, by viewing the electromyography (EMG) signals and the duty cycle of the PWM wave that controls the pneumatic robot's valves and pump as the inputs, the linear Koopman model accurately captures the complex human-robot interaction dynamics. Next, based on the obtained Koopman model, we further use Model Predictive Control (MPC) to control the soft robot and help the user to do rehabilitation training in real-time. The goal of the rehabilitation training is to track a given reference signal shown on the screen. Experiments show that by integrating the EMG signals into the Koopman model, we have improved the model accuracy to great extent. In addition, a personalized Koopman model trained from the individual's own data performs better than the non-personalized model. Consequently, our control framework outperforms the traditional PID control in both passive and active training modes. Hence the proposed method provides a new control framework for soft rehabilitation robots.
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