Experimental studies on the human gait using a tethered pelvic assist device (T-PAD)

Vashista, Vineet; Mustafa, Shabbir Kurbanhusen; Agrawal, Sunil K.

doi:10.1109/icorr.2011.5975472

Cited by 15 publications

(6 citation statements)

References 16 publications

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“…The marker set was similar to the one used in [33]. Surface EMG activity from the lower limb muscles were measured bilaterally, namely Femoris (BF) of both legs.…”

Section: Protocolmentioning

confidence: 99%

Locomotor Adaptation to an Asymmetric Force on the Human Pelvis Directed Along the Right Leg

Vashista

Martelli

Agrawal

2016

IEEE Trans. Neural Syst. Rehabil. Eng.

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In this work, we study locomotor adaptation in healthy adults when an asymmetric force vector is applied to the pelvis directed along the right leg. A cable-driven Active Tethered Pelvic Assist Device (A-TPAD) is used to apply an external force on the pelvis, specific to a subject's gait pattern. The force vector is intended to provide external weight bearing during walking and modify the durations of limb supports. The motivation is to use this paradigm to improve weight bearing and stance phase symmetry in individuals with hemiparesis. An experiment with nine healthy subjects was conducted. The results show significant changes in the gait kinematics and kinetics while the healthy subjects developed temporal and spatial asymmetry in gait pattern in response to the applied force vector. This was followed by aftereffects once the applied force vector was removed. The adaptation to the applied force resulted in asymmetry in stance phase timing and lower limb muscle activity. We believe this paradigm, when extended to individuals with hemiparesis, can show improvements in weight bearing capability with positive effects on gait symmetry and walking speed.

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“…The marker set was similar to the one used in [33]. Surface EMG activity from the lower limb muscles were measured bilaterally, namely Femoris (BF) of both legs.…”

Section: Protocolmentioning

confidence: 99%

Locomotor Adaptation to an Asymmetric Force on the Human Pelvis Directed Along the Right Leg

Vashista

Martelli

Agrawal

2016

IEEE Trans. Neural Syst. Rehabil. Eng.

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“…While our PIcontroller did not include the damping-injection term, it is possible the hysteresis from the Thera-band springs contributed to better force tracking. Perhaps similar non-steel springs with low weight and high hysteresis could be beneficial in other rehabilitation robots with long suspended cables [22], [26], [39], [48].…”

Section: B Series Elastic Element Stiffness Optimizationmentioning

confidence: 99%

“…Recently, there have been multiple new devices that can apply forces during specific portions of the gait cycle. A research group from Columbia University developed different multi-cable systems that can apply forces and moments in different directions at the pelvis [23]- [26]. A motorized version of their system can apply a net force that dynamically tracks the direction of the ground reaction force of the legs and could be used to elicit certain desirable compensatory after-effects when the device is turned off in individuals with hemiparesis [24].…”

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confidence: 99%

A System for Simple Robotic Walking Assistance With Linear Impulses at the Center of Mass

Gonabadi

Antonellis

Malcolm

2020

IEEE Trans. Neural Syst. Rehabil. Eng.

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Walking can be simplified as an inverted pendulum motion where both legs generate linear impulses to redirect the center of mass (COM) into every step. In this work, we describe a system to assist walking in a simpler way than exoskeletons by providing linear impulses directly at the COM instead of providing torques at the joints. We developed a novel waist end-effector and highlevel controller for an existing cable-robot. The controller allows for the application of cyclic horizontal force profiles with desired magnitudes, timings, and durations based on detection of the step timing. By selecting a lightweight rubber series elastic element with optimal stiffness and carefully tuning the gains of the closed-loop proportionalintegral-derivative (PID) controller in a number of singlesubject experiments, we were able to reduce the within-step root mean square error between desired and actual forces up to 1.21% of body weight. This level of error is similar or lower compared to the performance of other robotic tethers designed to provide variable or constant forces at the COM. The system can produce force profiles with peaks of up to 15 ± 2% of body weight within a root mean square error (RMSE) of 2.5% body weight. This system could be used to assist patient populations that require levels of assistance that are greater than current exoskeletons and in a way that does not make the user rely on vertical support. Index Terms-Aiding force, cable robotics, center of mass (COM), rehabilitation, walking. I. INTRODUCTION T HE field of wearable robots for assisting walking has witnessed an evolution from advanced, sophisticated devices that assist multiple joints [1]-[3] towards a greater focus on single-joint exoskeletons [4]-[9] and elegant, simple Manuscript

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“…Each subject was suited up with retro-reflective markers to record the human motion data [21]. Surface EMG activities from the lower limb muscles were measured bilaterally, namely Gastrocnemius (GAS), Soleus (SOL), and Tibialis Anterior (TA).…”

Section: Human Experimentsmentioning

confidence: 99%

A Novel Approach to Apply Gait Synchronized External Forces on the Pelvis Using A-TPAD to Reduce Walking Effort

Vashista

Khan

Agrawal

2016

IEEE Robot. Autom. Lett.

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In this paper, we develop an intervention to apply external gait synchronized forces on the pelvis to reduce the user’s effort during walking. A cable-driven robot was used to apply the external forces and an adaptive frequency oscillator scheme was developed to adapt the timing of force actuation to the gait frequency during walking. The external forces were directed in the sagittal plane to assist the trailing leg during the forward propulsion and vertical deceleration of the pelvis during the gait cycle. A pilot experiment with five healthy subjects was conducted. The results showed that the subjects applied lower ground reaction forces in the vertical and anterior-posterior directions during the late stance phase. In summary, the current work provides a novel approach to study the role of external pelvic forces in altering the walking effort. These studies can provide better understanding for designing exoskeletons and prosthetic devices to reduce the overall walking effort.

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Experimental studies on the human gait using a tethered pelvic assist device (T-PAD)

Cited by 15 publications

References 16 publications

Locomotor Adaptation to an Asymmetric Force on the Human Pelvis Directed Along the Right Leg

Locomotor Adaptation to an Asymmetric Force on the Human Pelvis Directed Along the Right Leg

A System for Simple Robotic Walking Assistance With Linear Impulses at the Center of Mass

A Novel Approach to Apply Gait Synchronized External Forces on the Pelvis Using A-TPAD to Reduce Walking Effort

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