Achilles: An autonomous lightweight ankle exoskeleton to provide push-off power

Meijneke, C.; Dijk, W. van; Kooij, Herman van der

doi:10.1109/biorob.2014.6913898

Cited by 42 publications

(40 citation statements)

References 17 publications

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“…(ii) Low Power Consumption: The CLs KAFO power consumption was minimized by means of a novel transmission system design with optimized reduction ratio. Both actuators deliver high torques with motors of less than 100W, lower than most of the motors used in previous studies [23], [24], [29]. The knee actuator, which is approximately irreversible, does not require additional electrical power in the critical weightacceptance gait phase, as the applied external torque is fully supported by the elastic component of the mechanism.…”

Section: A Mechatronics Of the Kafomentioning

confidence: 95%

“…Similar to Active Knee Orthoses, active Ankle-Foot orthoses (AFOs) aim to assist the plantar/dorsiflexion of the ankle and can be powered by different types of actuators, including pneumatic muscles [19], [20] and electric motors [21]- [24], some of which use a SEA architecture [23], [24]. Most AFOs are actuated by powerful motors of more than 120W, reaching torque peaks of about 25 N•m.…”

Section: B Active Ankle Orthosesmentioning

confidence: 99%

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A Knee–Ankle–Foot Orthosis to Assist the Sound Limb of Transfemoral Amputees

Sanz-Morère

Fantozzi

Parri

et al. 2019

IEEE Trans. Med. Robot. Bionics

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As a consequence of limb loss, trans-femoral amputees exert 60% additional knee extension torque and 50% more plantar flexion torque in the healthy limb compared to nonamputees. In this paper, we developed an active knee-ankle-foot orthosis (KAFO) designed to assist the healthy leg of transfemoral amputees in activities of daily living, such as walking, ascending/descending stairs, and transitioning from sit-to-stand with adequate range of motion, speed, and peak torque. Our KAFO was designed to exceed the performance of similar assistive devices reported in literature in terms of: 1) portability; 2) power; 3) compliance; and 4) versatility. It is based on onedegree-of-freedom active series-elastic actuators in both the knee and ankle, with an additional passive degree of freedom at the ankle level to allow natural inversion/eversion. The knee module consists of a worm-gear surrounded by two pre-compressed springs. The ankle actuator relies on a mechanically adjustable compliance system combined with a 4-bar linkage transmission. The actuators were designed to optimize the torque output at the joints while fulfilling low-power requirements. This novel KAFO is controlled with a three-layer structure. The optimized low level, based on a closed-loop torque controller, has adequate performances for the targeted application. The device is also shown to fulfill the three pre-defined functional requirements for all locomotion modes.

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Section: A Mechatronics Of the Kafomentioning

confidence: 95%

Section: B Active Ankle Orthosesmentioning

confidence: 99%

A Knee–Ankle–Foot Orthosis to Assist the Sound Limb of Transfemoral Amputees

Sanz-Morère

Fantozzi

Parri

et al. 2019

IEEE Trans. Med. Robot. Bionics

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“…Subjects (N=2) wore the Achilles [13], a motorized ankle exoskeleton which provided various amounts of bilateral torque assistance. Subjects walked at their preferred speed (1.06 m/s, 1.08 m/s) and at a slow speed (0.58 m/s) on an instrumented split-belt treadmill.…”

Section: A Neuromuscular Controllermentioning

confidence: 99%

Effects of a neuromuscular controller on a powered ankle exoskeleton during human walking

Dzeladini

Renjewski

et al. 2016

2016 6th IEEE International Conference on Biomedical Robotics and Biomechatronics (BioRob)

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Abstract-Wearable devices to assist abnormal gaits require controllers that interact with the user in an intuitive and unobtrusive manner. To design such a controller, we investigated a bio-inspired walking controller for orthoses and prostheses. We present (i) a Simulink neuromuscular control library derived from a computational model of reflexive neuromuscular control of human gait with a central pattern generator (CPG) extension, (ii) an ankle reflex controller for the Achilles exoskeleton derived from the library, and (iii) the mechanics and energetics of healthy subjects walking with an actuated ankle orthosis using the proposed controller. As this controller was designed to mimic human reflex patterns during locomotion, we hypothesize that walking with this controller would lead to lower energetic costs, compared to walking with the added mass of the device only, and allow for walking at different speeds without explicit control. Preliminary results suggest that the neuromuscular controller does not disturb walking dynamics in both slow and normal walking cases and can also reduce the net metabolic cost compared to transparent mode of the device. Reductions in tibialis anterior and soleus activity were observed, suggesting the controller could be suitable, in future work, for augmenting or replacing normal walking functions. We also investigated the impedance patterns generated by the neuromuscular controller. The validity of the equivalent variable impedance controller, particularly in stance phase, can facilitate serving subject-specific features by linking impedance measurement and neuromuscular controller.

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“…Series elastic actuators (SEA) with their compliant properties are a popular choice for lower limb exoskeletons [1]- [4], humanoid robots [5], [6], and powered prostheses [7]- [10]. However, despite their regular use for robots involved in locomotion, the control of SEAs used for locomotion remains challenging.…”

Section: Introductionmentioning

confidence: 99%

An Improved Force Controller With Low and Passive Apparent Impedance for Series Elastic Actuators

Rampeltshammer

Keemink

Kooij

2020

IEEE/ASME Trans. Mechatron.

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This work presents a force controller for series elastic actuators that are used in gait robots such as exoskeletons, prostheses, and humanoid robots. Therefore, the controller needs to increase the bandwidth of the actuator, lower its apparent impedance for disturbance rejection or effortless interaction with a human user, and to stably interact with any (dynamic) environment. For gait, these environments are changing discontinuously, thus creating regular impacts. In this work, we propose the use of an inner loop PD controller to increase the bandwidth of the actuator, alongside an outer loop disturbance observer (DOB) to lower the apparent impedance of the actuator. To increase the controlled bandwidth of the actuator, we introduce a novel tuning method for the PD controller that allows for independent tuning of bandwidth and damping ratio of the controlled plant. The DOB, which is introduced to reject disturbances by lowering the apparent impedance, causes the apparent impedance to turn non-passive, resulting in potential contact and coupled instability of the actuator. To enable unconditionally stable interactions with any environment, we scale down the DOB contribution such that it lowers the apparent impedance while remaining passive. The proposed tuning method and DOB adaptation were evaluated on a test-setup by identifying the torque controller's transfer behavior and by identifying the apparent impedance of the actuator. The results of these tests showed that the proposed tuning method can separately tune bandwidth and damping ratio, while the DOB adaptation is able to trade-off the reduction of the apparent impedance with its passivity.

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Achilles: An autonomous lightweight ankle exoskeleton to provide push-off power

Cited by 42 publications

References 17 publications

A Knee–Ankle–Foot Orthosis to Assist the Sound Limb of Transfemoral Amputees

A Knee–Ankle–Foot Orthosis to Assist the Sound Limb of Transfemoral Amputees

Effects of a neuromuscular controller on a powered ankle exoskeleton during human walking

An Improved Force Controller With Low and Passive Apparent Impedance for Series Elastic Actuators

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