Effect of Variability on Fall Risk and Energetic Cost in Biped Walking

当人和机器人行走时，他们每走一步都是大致相同的运动，但并不完全相同。他们动作的差异似乎增加了跌倒的风险。这种变异性（运动差异）与跌倒事件之间的确切关系尚不清楚。变异性也可能影响行走所需的能量，但变异性和所需能量之间的关系仍然是未知的。稳健性定义为实现降低的跌倒风险，并且尽管存在变异性，也需要最小的能量。本项目将确定可变性的哪些方面会降低稳健性。该项目还将研究增加步态的双支撑期（双脚着地的时期）的持续时间是否会增加鲁棒性。这项研究将导致一种诊断工具，以确定跌倒的可能性。该工具可以为临床医生提供有价值的见解，了解步行步态的变化如何影响跌倒风险。这项工作还将提高机器人的能力，这反过来将大大提高它们的实用性。跌倒风险诊断工具将被改编成一个实验活动，为初中和高中生介绍诊断和估计的概念。预计该研究将通过加强工程与人民福祉之间的联系来扩大参与。该项目将涉及理论和仿真为基础的工作，将考虑如何一个新的组合的双支持控制器和联合可变性改变鲁棒性。本研究将开发多个双支撑控制器，并通过理论和仿真证明，增加双支撑周期的持续时间增加鲁棒性。将比较不同的双支撑对照配方，并确定导致最稳健步态的配方。使用模拟，通过系统地改变建模的变异性并模拟步态，直到模型福尔斯倒下，分析每个关节的幅度、频率和连续性在关节变异性中的作用。由于一个关节的变异性可能与其他关节的变异性相互作用，因此将使用部分析因实验设计范式对其进行改变。本研究将使用模拟来确定哪些容易测量的步态特征与鲁棒性相关。这些测量结果将结合起来，形成一个诊断工具，可以准确地预测步态鲁棒性使用计算现实的步骤数。诊断工具将用于设计新的步态，优化的鲁棒性。

When both people and biped robots walk, they move through approximately the same motion at every step, but not exactly the same motion. The differences in their motions appear to contribute to the risk of falling. The exact relationship between this variability (differences in motion) and falling events is unknown. Variability may also affect how much energy is required to walk but again the relationship between variability and energy required is unknown. The robustness is defined as achieving a reduced risk of falling and also requiring minimum energy in spite of the presence of variability. This project will determine which aspects of variability decrease robustness. The project will also investigate if increasing the duration of the double support period of gait (the period when both feet are on the ground) increases robustness. The research will lead to a diagnostic tool to determine likelihood of biped falling. This tool can provide clinicians with valuable insights into how changes in walking gaits affect the fall risk. This work will also lead to improved capabilities for biped robots, which in turn will significantly increase their utility. The fall risk diagnostic tool will be adapted into an experimental activity for middle and high schoolers to introduce the concepts of diagnostics and estimation. The research is expected to broaden participation by strengthening the connection between engineering and people's wellbeing. The project will involve theoretical- and simulation-based work that will consider how a novel combination of the double support controller and joint variability alters robustness. This study will develop multiple double support controllers and prove both theoretically and through simulation that increasing the duration of the double support period increases robustness. Different double support control formulations will be compared, and the formulation that results in the most robust gait will be determined. Using simulations, the role of the magnitude, frequency, and continuity in joint variability at each joint will be analyzed by systematically altering the modeled variability and simulating the gait until the model falls. Because variability at one joint is likely to interact with variability at other joints, it will be altered using a fractional factorial experimental design paradigm. This study will use the simulations to determine which easily measurable gait characteristics are correlated with robustness. These measurements will be combined to form a diagnostic tool that can accurately predict gait robustness using a computationally realistic number of steps. The diagnostic tool will be used to design new gaits that are optimized for robustness.