Walking can be simplified as an inverted pendulum motion where both legs generate linear impulses to redirect the center of mass (COM) into every step. In this work, we describe a system to assist walking in a simpler way than exoskeletons by providing linear impulses directly at the COM instead of providing torques at the joints. We developed a novel waist end-effector and high-level controller for an existing cable-robot. The controller allows for the application of cyclic horizontal force profiles with desired magnitudes, timings, and durations based on detection of the step timing. By selecting a lightweight rubber series elastic element with optimal stiffness and carefully tuning the gains of the closed-loop proportional–integral–derivative (PID) controller in a number of single-subject experiments, we were able to reduce the within-step root mean square error between desired and actual forces up to 1.21% of body weight. This level of error is similar or lower compared to the performance of other robotic tethers designed to provide variable or constant forces at the COM. The system can produce force profiles with peaks of up to 15 ± 2% of body weight within a root mean square error (RMSE) of 2.5% body weight. This system could be used to assist patient populations that require levels of assistance that are greater than current exoskeletons and in a way that does not make the user rely on vertical support.

中文翻译：

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在质心处具有线性脉冲的简单机器人步行辅助系统

步行可以简化为倒立摆运动，其中双腿产生线性脉冲，以将质心（COM）重新定向到每一步。在这项工作中，我们描述了一种系统，该系统通过直接在COM处提供线性脉冲而不是在关节处提供扭矩来以比外骨骼更简单的方式帮助步行。我们为现有的电缆机器人开发了一种新颖的腰部末端执行器和高级控制器。控制器允许基于步进时间的检测，以所需的大小，时间和持续时间应用循环水平力曲线。通过选择具有最佳刚度的轻质橡胶系列弹性元件，并在许多单项实验中仔细调整闭环比例-积分-微分（PID）控制器的增益，我们能够将期望力和实际力之间的步内均方根误差减小至体重的1.21％。与设计用于在COM上提供可变或恒定力的其他机械手系绳的性能相比，此错误级别近似或更低。该系统可产生力分布图，其峰值最高可达体重的15±2％，而均方根误差（RMSE）为2.5％体重。该系统可用于帮助需要比当前外骨骼更大的帮助水平的患者人群，并且这种方式不会使用户依赖垂直支撑。该系统可产生力分布图，其峰值最高可达体重的15±2％，而均方根误差（RMSE）为2.5％体重。该系统可用于帮助需要比当前外骨骼更大的帮助水平的患者人群，并且这种方式不会使用户依赖垂直支撑。该系统可产生力分布图，其峰值最高可达体重的15±2％，而均方根误差（RMSE）为2.5％体重。该系统可用于帮助需要比当前外骨骼更大的帮助水平的患者人群，并且这种方式不会使用户依赖垂直支撑。