Mapping ankle-foot stiffness to socket comfort and pressure using a robotic emulator platform to personalize prosthesis function via human-in-the-loop optimization

这项初步研究的主要目的是表征假肢踝足刚度， 用户报告的经胫骨截肢退伍军人的舒适度和残余物-关节窝界面压力，以及使用 这些关系指导假体优化，以最大限度地提高日常舒适度。用户舒适度至关重要 重要性，并直接影响到满意度与假肢，使用或拒绝 一个假肢，最终的行动能力和独立性。在美国，近90%的假肢临床病例 与下肢相关，代表了绝大多数已交付的假体器械干预。然而，在这方面， 调查表明，33%至57%的假肢使用者对舒适度不满意， 39%的人表示舒适度和适合度是他们对新假肢最关心的问题 也是更换修复师的主要原因此外，51%和37%的越南退伍军人和OIF/OEF 服务人员报告了假体相关疼痛。重要的是，定期使用假体和满意度 它的舒适性可以增加下肢丧失后重返工作岗位的可能性，这是一个关键因素， 退伍军人重返社区。自我感知舒适度是一个多因素的、动态的、心理物理的结构， 但有证据表明，它是受残体-窝界面压力的影响。这些界面压力是 受接受腔设计的影响，但也受假体对线的影响，因为它对地面反应的转移有影响 力通过关节窝到达近端解剖结构。通过相同的机制，假体刚度也应该 理论上影响界面压力，但这种关系尚未量化。为此，假肢 可以调节性能以操纵界面压力以使舒适度最大化。因此，具体目标 本研究的主要内容是：1）定义连接假足刚度，残余-接受腔界面压力， 和用户感知的舒适度，以及2）评估人在回路优化的功效以调整假足 除了临床优化的插座外，还具有最小化界面压力的刚度。 我们将通过使用新型机器人假肢仿真器平台来实现研究目标，该平台包括一个高性能的 高性能机电一体化系统，用于快速、可控和高分辨率的龙骨刚度调制， 拴系假肢踝足末端执行器。这两个目标将涉及10名单侧经胫骨的参与者 截肢对于目标1，参与者将首先接受模拟器系统的调试和适应， 协议，然后在不同的假体踝足刚度设置下以稳态行走， 特定于他们的体重的参考值的一定百分比，其反映了共同的动态弹性 脚的反应。将在每个刚度设置下测量峰值界面压力和关节窝舒适度， 通过线性混合模型和曲线评估刚度、舒适度和压力之间的关联 拟合对于目标2，参与者还将接受模拟器系统的调试和适应，然后 经历一个被称为人在回路优化的过程，其中假体龙骨刚度将被 使用专注于最小化接口的贝叶斯控制算法实时自动优化 压力成本函数和最大化舒适度。除了不断反馈参与者的经验外， 将在优化刚度设置之间比较峰值压力、窝舒适度和感知力 以及目标1的参考刚度设置。[For这两个目标，下肢运动学将被测量， 评估刚度对步态表现的影响。]这项研究的结果将为临床上重要的 假体刚度、界面压力和舒适度之间的关系，以指导 最大化退伍军人假肢使用者的行走舒适度。我们的成果也将为发展奠定基础 智能假肢通过未来的优异奖，自动实现刚度调整， 压力生物反馈，以保持长期退伍军人日常舒适，假肢使用和独立性。

The primary aim of this pilot study is to characterize the relationships between prosthetic ankle-foot stiffness, user reported comfort, and residuum-socket interface pressure in Veterans with transtibial amputation, and use these relationships to guide prosthesis optimization to maximize daily comfort. User comfort is of paramount importance to leg prosthesis users and has a direct impact on satisfaction with a prostheses, use or rejection of a prosthesis, and ultimately mobility and independence. Nearly 90% of prosthetic clinical encounters in the US are related to the lower limb, representing the vast majority of delivered prosthetic device interventions. However, surveys suggest that between 33% and 57% of leg prosthesis users report dissatisfaction with comfort while wearing their prosthesis, and 39% indicated that comfort and fit were their biggest concerns with a new prosthesis and a primary reason for changing prosthetists. Moreover, 51% and 37% of Vietnam Veterans and OIF/OEF Service Members reported prosthesis related pain. Importantly, regular use of a prosthesis and satisfaction with its comfort can increase the likelihood of returning to work following lower limb loss and this is a critical factor to Veterans’ community reintegration. Self-perceived comfort is a multifactorial, dynamic, psychophysical construct, but evidence suggests it is influenced by residuum-socket interface pressures. These interface pressures are affected by socket design, but also by prosthesis alignment given its influence on transfer of ground reaction forces through the socket to proximal anatomy. By the same mechanism, prosthesis stiffness should also theoretically affect interface pressures, but this relationship has not been quantified. To this end, prosthesis properties could be tuned to manipulate interface pressures for maximizing comfort. Therefore, the Specific Aims of this study are: 1) Define the maps connecting prosthetic foot stiffness, residuum-socket interface pressures, and user-perceived comfort, and 2) Assess the efficacy of human-in-the-loop optimization to tune prosthetic foot stiffness for minimizing interface pressure independent and in addition to the clinically optimized socket. We will address the study aims through use of novel robotic prosthesis emulator platform that includes a high- performance mechatronic system for rapid, controlled, and high-resolution keel stiffness modulations of a tethered prosthetic ankle-foot end effector. Both aims will involve ten participants with unilateral transtibial amputation. For Aim 1, participants will first undergo fitting and accommodation to the emulator system and protocol, and then walk at steady state under different prosthesis ankle-foot stiffness settings stratified by a certain percentage from a reference value specific to their body mass that reflects a common dynamic elastic response foot. Peak interface pressures and socket comfort will be measured at each stiffness setting to quantify associations between stiffness, comfort, and pressures as assessed through linear mixed modelling and curve fitting. For Aim 2, participants will also undergo fitting and accommodation to the emulator system, and then experience a process known as human-in-the-loop optimization in which the prosthesis keel stiffness will be automatically optimized in real-time using Bayesian control algorithms focused on minimizing an interface pressure cost function and maximizing comfort. In addition to continuous feedback on participant experience, peak pressures, socket comfort, and perceived effort will be compared between the optimized stiffness setting and the reference stiffness setting of Aim 1. [For both aims, lower extremity kinematics will be measured to assess stiffness effects on gait performance.] Results from this study will inform on the clinically important relationships between prosthesis stiffness, interface pressures, and comfort to guide prescription guidelines for maximizing walking comfort in Veteran prosthesis users. Our results will also set the foundation for development of a smart prosthesis through future Merit Awards that automatically implements stiffness adjustments according to pressure biofeedback to maintain long-term Veteran daily comfort, prosthesis use, and independence.