This article features a novel sliding mode controller for robotic arms using nonlinear model-based switching functions. The new controller is experimentally validated on a 7-DOF exoskeleton arm used for upper-limb rehabilitation applications. The proposed approach features a novel concept using model-based switching functions in the sliding mode controller, which leads to considerable simplifications on the torque control inputs. Compared to conventional linear switching functions, model-based switching functions show substantial control performance improvements on the torque inputs, such as transient constraints reduction and enhanced robustness, while maintaining a very good tracking performance. Moreover, model-based switching functions design ensures a complete decoupling of chattering effect between joint axes. Furthermore, this approach can be combined with existing chattering reduction techniques to ensure proper control of chattering levels on the torque inputs. These advantages make the practical implementation of the model-based switching functions approach particularly desirable for wearable robotics, where smooth movements and high accuracy are important requirements for patients’ comfort and security.

中文翻译：

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具有基于模型的切换功能的滑模控制应用于7自由度外骨骼臂

本文介绍了一种使用基于非线性模型的切换功能的新型机械臂滑模控制器。新控制器已在用于上肢康复应用的7自由度外骨骼臂上经过实验验证。所提出的方法具有在滑模控制器中使用基于模型的开关功能的新颖概念，从而导致转矩控制输入的相当大的简化。与传统的线性开关功能相比，基于模型的开关功能在转矩输入方面显示出了显着的控制性能改进，例如瞬态约束减小和鲁棒性增强，同时保持了非常好的跟踪性能。此外，基于模型的切换功能设计确保关节轴之间的抖振效果完全脱开。此外，这种方法可以与现有的抖振减小技术结合使用，以确保正确控制扭矩输入上的抖振水平。这些优点使基于模型的切换功能方法的实际实现特别适用于可穿戴机器人，其中平稳运动和高精度是患者舒适度和安全性的重要要求。