Stand-Up, Squat, Lunge, and Walk With a Robotic Knee and Ankle Prosthesis Under Shared Neural Control

Abstract

We propose a shared neural control approach combining neural signals from the user's residual limb with robot control to improve functional mobility in individuals with above-knee amputation. The proposed shared neural controller enables subjects to stand up under a variety of conditions, squat, lunge, walk, and seamlessly transition between activities which is not possible with other prostheses or controllers. Further, we show that the proposed shared neural controller reduces muscle effort and increased symmetry during standing up compared to conventional passive prostheses. No other available technology can enable individuals with above-knee amputations to achieve this level of mobility.

Effect of Increasing Assistance From a Powered Prosthesis on Weight-Bearing Symmetry, Effort, and Speed During Stand-Up in Individuals With Above-Knee Amputation

“…In contrast, powered ankles can actively dorsiflex before the stand-up movement begins and allow the user to select a natural starting position. This functional difference may be the underlying reason why the only significant improvements in weight bearing symmetry and muscle effort during stand-up with powered prosthetics have been shown in studies with powered knees combined with powered ankles [14], [15]. Future studies should investigate the role of the ankle by controlling the ankle torque based on ablebodied ankle torque profiles, including testing increased ankle torque with and without corresponding increases in knee torque.…”

“…In contrast, a study with a research powered knee and powered ankle combined significantly improved weight-bearing symmetry, although some subjects needed to use armrests while standing up, decreasing the reliability of the results [14]. A recent case series with a TNSRE-2022-00328.R2 powered knee and powered ankle has shown improved weightbearing symmetry and muscle effort during standing-up using a proportional electromyographic (EMG) controller, with the subject directly controlling the amount of assistance at each point in time [15]. However, we still lack essential knowledge about how to tune powered prostheses to best assist users.…”

“…Because the prosthesis, socket, and residual limb are structurally different from healthy limbs, controlling a powered prosthesis to provide a level of torque that is higher or lower than that of healthy legs may lead to better outcomes. Only three research groups have reported the amount of assistive torque produced by a powered prosthesis during stand-up [14], [15], [17]. No study has systematically investigated multiple levels of torque.…”

Powered knee and ankle prostheses enable natural ambulation on level ground and stairs for individuals with bilateral above-knee amputation: a case study

“…Bilateral above-knee amputation severely limits ambulation ability and quality of life 1 , 3 , 4 . Powered prostheses have the potential to address this problem by closely replicating the biomechanical functions of the missing legs during virtually all ambulation activities 17 , 18 , 23 , 24 , 28 . Two previous case studies 15 , 16 have shown that powered knee and ankle prostheses can enable an individual with bilateral above-knee amputation to walk on level ground.…”

An Adaptive Hybrid Control Architecture for an Active Transfemoral Prosthesis

“…Apart from the state machine and echo control strategies, in the past few years, significant efforts have also been made using electromyography (EMG) from residual-limb muscles to classify user intent and then impose a pre-determined gait trajectory. Progress using this method has been demonstrated in [12], [21]- [23] and [17]. Furthermore, in recent times with the improvement in processing power of onboard computers, computer vision and range sensors, have also been proposed to improve classification accuracy, as shown in [24], [25] and [26].…”