For robotic transtibial prosthesis control, the global kinematics of the tibia can be used to monitor the progression of the gait cycle and command smooth and continuous actuation. In this work, these global tibia kinematics are used to define a phase variable impedance controller (PVIC), which is then implemented as the nonvolitional base controller within a hybrid volitional control framework (PVI-HVC). The gait progression estimation and biomechanic performance of one able-bodied individual walking on a robotic ankle prosthesis via a bypass adapter are compared for three control schemes: a passive benchmark controller, PVIC, and PVI-HVC. The different actuation of each controller had a direct effect on the global tibia kinematics, but the average deviation between the estimated and ground truth gait percentage were 1.6%, 1.8%, and 2.1%, respectively, for each controller. Both PVIC and PVI-HVC produced good agreement with able-bodied kinematic and kinetic references. As designed, PVI-HVC results were similar to those of PVIC when the user used low volitional intent, but yielded higher peak plantarflexion, peak torque, and peak power when the user commanded high volitional input in late stance. This additional torque and power also allowed the user to volitionally and continuously achieve activities beyond level walking, such as ascending ramps, avoiding obstacles, standing on tip-toes, and tapping the foot. In this way, PVI-HVC offers the kinetic and kinematic performance of the PVIC during level ground walking, along with the freedom to volitionally pursue alternative activities.

翻译：在机器人小腿假肢控制中，胫骨的整体运动学可用于监测步态周期的进展，并实现平滑连续的驱动。本研究利用这些整体胫骨运动学定义了一种相位变量阻抗控制器（PVIC），并将其作为非意向基础控制器，嵌入混合意向控制框架（PVI-HVC）中。通过旁路适配器使一位健全个体在机器人踝关节假肢上行走，对比了三种控制方案（被动基准控制器、PVIC和PVI-HVC）的步态进程估计精度与生物力学性能。各控制器的不同驱动方式对整体胫骨运动学产生直接影响，但三种控制器下估计步态百分比与真实值的平均偏差分别为1.6%、1.8%和2.1%。PVIC和PVI-HVC均与健全个体的运动学及动力学参考值高度吻合。如设计预期，当使用者低意向需求时，PVI-HVC结果与PVIC相似；但在站立末期若使用者下达高意向指令，PVI-HVC则产生更高的峰值跖屈、峰值扭矩及峰值功率。这种额外的扭矩与功率还允许使用者有意向地持续完成超越平地行走的活动，如爬坡、避障、踮脚站立及足部拍击。由此可见，PVI-HVC在平地行走时能保持PVIC的动力学与运动学性能，同时赋予使用者有意向探索其他活动的自由。