Haptic upper limb exoskeletons are robots that assist human operators during task execution while having the ability to render virtual or remote environments. Therefore, the stability of such robots in physical human-robot-environment interaction must be guaranteed, in addition to performing well during task execution. Having a wide range of Z-width, which shows the region of passively renderable impedance by a haptic display, is also important to render a wide range of virtual environments. To address these issues, in this study, subsystem-based adaptive impedance control is designed for having a stable human-robot-environment interaction of 7 degrees of freedom haptic exoskeleton. The presented control decomposes the entire system into subsystems and designs the controller at the subsystem level. The stability of the controller in the presence of contact with the virtual environment and human arm force is proved by employing the virtual stability concept. Additionally, the Z-width of the 7-DoF haptic exoskeleton is drawn using experimental data and improved using varying virtual mass element for the virtual environment. Finally, experimental results are provided to demonstrate the perfect performance of the proposed controller in accomplishing the predefined task.

翻译：触觉上肢外骨骼是一种在执行任务时辅助人类操作者，同时能够渲染虚拟或远程环境的机器人。因此，除了在任务执行过程中表现出色外，还必须保证此类机器人在物理人-机器人-环境交互中的稳定性。具有广泛的Z宽度（即触觉显示器可被动渲染的阻抗范围）对于渲染多种虚拟环境也至关重要。为应对这些问题，本研究设计了一种基于子系统的自适应阻抗控制，以实现七自由度触觉外骨骼的稳定人-机器人-环境交互。所提出的控制方法将整个系统分解为子系统，并在子系统层级设计控制器。通过采用虚拟稳定性概念，证明了控制器在接触虚拟环境和人体手臂力时的稳定性。此外，利用实验数据绘制了七自由度触觉外骨骼的Z宽度，并通过引入虚拟环境中的可变虚拟质量元件对其进行了改进。最后，实验结果展示了所提控制器在完成预定任务时的出色性能。