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：触觉上肢外骨骼是辅助操作者在任务执行过程中与虚拟或远程环境交互的机器人。因此，除了在任务执行中表现良好外，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。同时，具有较宽的Z宽度（即触觉显示器可被动呈现阻抗的区域）对于渲染多样化的虚拟环境也至关重要。为解决这些问题，本研究针对七自由度触觉外骨骼设计了一种基于子系统的自适应阻抗控制，以实现稳定的人-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，并在子系统层面设计控制器。通过应用虚拟稳定性概念，证明了该控制器在与虚拟环境及人体手臂力接触时的稳定性。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的可变虚拟质量元素对其进行了改进。最后，实验结果表明该控制器在完成预定任务中具有优异性能。