Intelligent control strategies for active biomimetic prostheses could exploit the inter-joint coordination of limbs in human gait in order to mimic the functioning of a biological joint. A machine learning regression model could be employed to learn an input-output relationship between the coordinated limb motion in human gait and predict the motion of a particular limb/joint given the motion of other limbs/joints. Such a model could be potentially used as a controller for an intelligent prosthesis which aims to restore the functioning similar to an intact biological joint. For this, the model needs to be tailored for each user by learning the gait pattern specific to the user. The challenge of training such machine learning regression models in prosthetic control is that, the desired reference output cannot be obtained from an amputee due to the missing limb. In this study, we investigate the feasibility of using two different methods for training a random forest algorithm using incomplete amputee-specific data to predict the ankle kinematics and dynamics from hip, knee, and shank kinematics. First is an inter-subject approach which learns a generalized input-output relationship from a group of able-bodied individuals and then applies this generalized relationship to amputees. Second is a subject-specific approach which maps the amputee's inputs to a desired normative reference output calculated from able-bodied individuals. The subject-specific model outperformed the inter-subject model in predicting the ankle angle and moment in most cases and can be potentially used for devising a control strategy for an intelligent biomimetic ankle.

中文翻译：

---

使用不完整的用户特定数据训练随机森林模型以设计主动仿生脚踝控制策略的可行性

主动仿生假肢的智能控制策略可以利用人体步态中四肢的关节间协调来模拟生物关节的功能。机器学习回归模型可用于学习人类步态中协调肢体运动之间的输入-输出关系，并根据其他肢体/关节的运动预测特定肢体/关节的运动。这种模型有可能用作智能假肢的控制器，旨在恢复类似于完整生物关节的功能。为此，需要通过学习特定于用户的步态模式来为每个用户量身定制模型。在假肢控制中训练此类机器学习回归模型的挑战在于，由于肢体缺失，无法从截肢者那里获得所需的参考输出。在这项研究中，我们研究了使用两种不同方法训练随机森林算法的可行性，该算法使用不完整的截肢者特定数据来预测髋关节、膝关节和小腿运动学的踝关节运动学和动力学。首先是一种跨学科方法，它从一组健全的个体中学习广义的输入-输出关系，然后将这种广义关系应用于截肢者。第二个是特定主题的方法，它将截肢者的输入映射到从健全的个人计算出的所需规范参考输出。