Data-Driven Variable Impedance Control of a Powered Knee-Ankle Prosthesis for Sit, Stand, and Walk with Minimal Tuning

Welker, Cara Gonzalez; Best, T. Kevin; Gregg, Robert D.

doi:10.1109/iros47612.2022.9982037

Cited by 13 publications

(28 citation statements)

References 34 publications

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“…It may in fact improve clinical outcomes, as previous studies have reported that decreasing knee torque correlated with increased symmetry at the end of the motion [17]. In contrast to our prior work [15] and others [17] where torque magnitude had to be reduced from biomimetic kinetics to allow the pilot participant to sit down, all participants were able to effectively use the biomimetic knee torque during stand-to-sit without any changes (Figure 4c). Qualitative feedback from the participants, detailed further below, echoed this sentiment.…”

Section: Discussionmentioning

confidence: 61%

“…Although relatively sparse in the literature, there are examples of prior work investigating control strategies that allow a powered above-knee prosthesis user to transition between sitting and standing [11]- [17]. One commonly used approach is impedance control [11], [12], [15], which dictates the joint torque as a function of the joint's angular position θ and velocity θ, parameterized by a stiffness K, damping B, and equilibrium angle θ eq :…”

Section: Introductionmentioning

confidence: 99%

“…However, the preliminary sit-stand controller in [15] had a number of limitations that we address in the current manuscript. First, we previously used the same impedance parameter trajectories for both stand-to-sit and sit-to-stand motions, and similarly to [17], needed to reduce the torque magnitude below biomimetic values because our pilot participant felt that full stand-to-sit assistance made it difficult for him to sit down.…”

Section: Introductionmentioning

confidence: 99%

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Improving Sit/Stand Loading Symmetry and Timing Through Unified Variable Impedance Control of a Powered Knee-Ankle Prosthesis

Welker¹,

Best²,

Gregg³

2023

Preprint

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<p>Individuals using passive prostheses typically rely heavily on their biological limb to complete sitting and standing tasks, leading to slower completion times and increased rates of osteoarthritis and lower back pain. Powered prostheses can address these challenges, but have control methods that divide sit-stand transitions into discrete phases, limiting user synchronization across the motion and requiring long manual tuning times. This paper extends our preliminary work using a thigh-based phase variable to parameterize optimized data-driven impedance parameter trajectories for sitting, standing, and walking, with only two classification modes. We decouple the stand-to-sit and sit-to-stand equilibrium angles through a knee velocity-dependent scaling term, reducing the model fitting error by approximately half compared to our previous results. We then experimentally validate the controller with three individuals with above-knee amputation performing sitting and standing transitions to/from three different chair heights. We show that our controller implemented on a powered knee-ankle prosthesis produced biomimetic joint mechanics, resulting in significantly reduced sit/stand loading symmetry and time to complete a 5x sit-to-stand task compared to participants' passive prostheses. Integration with a previously developed walking controller also allowed sit/walk transitions between different chair heights. The controller's biomimetic assistance may reduce the overreliance on the biological limb caused by inadequate passive prostheses, helping improve mobility for people with above-knee amputations. </p>

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Section: Discussionmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improving Sit/Stand Loading Symmetry and Timing Through Unified Variable Impedance Control of a Powered Knee-Ankle Prosthesis

Welker¹,

Best²,

Gregg³

2023

Preprint

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“…The optimized four‐bar structure of the knee joint restores the biological knee joint motion characteristics (Figure 4). Moreover, conventional prostheses in joint synergistic motion mainly rely on control techniques 31,32 . In contrast, the series‐parallel hybrid multi‐objective drive structure (Figure 6) we proposed provides a new way for realizing joint synergistic motion.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, conventional prostheses in joint synergistic motion mainly rely on control techniques. 31,32 In contrast, the series-parallel hybrid multi-objective drive structure (Figure 6) we proposed provides a new way for realizing joint synergistic motion.…”

Section: Resultsmentioning

confidence: 99%

Design and optimization of a new integrated hip and knee prosthesis structure

Luo,

Shu,

Zhu

et al. 2023

Artificial Organs

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BackgroundConventional hip disarticulation prostheses (HDPs) are passive devices with separate joint structures, limiting amputees' ability to control and resulting in abnormal gait patterns. This study introduces a new HDP integrating the hip and knee joints for amputees' natural gait.MethodsThe new HDP restores the physiological rotation center of the hip with a remote center of motion (RCM) structure, and simulates the knee motion with a four‐bar structure. Nonlinear programming was employed to optimize the hip‐knee joint structure. A hybrid multi‐objective drive structure with a series–parallel connection was also designed to ensure motion synergy between the hip and knee joints. Finally, a prototype of the prosthesis was tested using the HDP test system.ResultsThe optimization results demonstrate that the new HDP accurately restores the rotation center of the femur in amputees, with the knee's instantaneous center of rotation (ICR) trajectory closely resembling that of the human knee (Pearson correlation coefficient is 0.999). The study shows that the new HDP achieves a motion reproduction accuracy of over 95% for the human hip joint at walking speeds above 1.5 km/h, 38% higher than conventional prosthesis. Similarly, at the same walking speed, the new HDP replicates the motion of the human knee at 82.89%, surpassing conventional prosthesis by 57.85%.ConclusionsThe new HDP restores symmetry and replicates synergistic movement in amputees' lower limbs, exhibiting superior movement characteristics compared to conventional prostheses. This innovative HDP has the potential to enhance the quality of life for amputees.

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A Robotic Ankle-Foot Prosthesis Based on Torsional Series and Parallel Elasticity

Mazzarini,

Fagioli,

Baldoni

et al. 2024

2024 10th IEEE RAS/EMBS International Conference for Biomedical Robotics and Biomechatronics (BioRob)

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Data-Driven Variable Impedance Control of a Powered Knee-Ankle Prosthesis for Sit, Stand, and Walk with Minimal Tuning

Cited by 13 publications

References 34 publications

Improving Sit/Stand Loading Symmetry and Timing Through Unified Variable Impedance Control of a Powered Knee-Ankle Prosthesis

Improving Sit/Stand Loading Symmetry and Timing Through Unified Variable Impedance Control of a Powered Knee-Ankle Prosthesis

Design and optimization of a new integrated hip and knee prosthesis structure

A Robotic Ankle-Foot Prosthesis Based on Torsional Series and Parallel Elasticity

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