A two-axis cable-driven ankle-foot mechanism

Ficanha, Evandro M.; Rastgaar, Mo; Kaufman, Kenton R.

doi:10.1186/s40638-014-0017-0

Cited by 22 publications

(20 citation statements)

References 21 publications

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“…Powered lower extremity prostheses usually have one degree of freedom (DOF) in the sagittal plane (Sup et al, 2009 ; Eilenberg et al, 2010 ; Hitt et al, 2010 ). The authors have developed a 2-DOF powered ankle–foot prosthesis with two controllable DOFs in the sagittal and frontal planes (Ficanha et al, 2014 , 2015c ). The design of powered ankle–foot prostheses generally considers the lower leg and ankle to be fixed in the transverse plane, since the hip joint is capable of generating the majority of torques that is transferred to the ground for steering and turning.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Impedance of the Non-loaded Lower Leg with Relaxed Muscles in the Transverse Plane

Ficanha

Ribeiro

Rastgaar

2015

Front. Bioeng. Biotechnol.

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This paper describes the protocols and results of the experiments for the estimation of the mechanical impedance of the humans’ lower leg in the External–Internal direction in the transverse plane under non-load bearing condition and with relaxed muscles. The objectives of the estimation of the lower leg’s mechanical impedance are to facilitate the design of passive and active prostheses with mechanical characteristics similar to the humans’ lower leg, and to define a reference that can be compared to the values from the patients suffering from spasticity. The experiments were performed with 10 unimpaired male subjects using a lower extremity rehabilitation robot (Anklebot, Interactive Motion Technologies, Inc.) capable of applying torque perturbations to the foot. The subjects were in a seated position, and the Anklebot recorded the applied torques and the resulting angular movement of the lower leg. In this configuration, the recorded dynamics are due mainly to the rotations of the ankle’s talocrural and the subtalar joints, and any contribution of the tibiofibular joints and knee joint. The dynamic mechanical impedance of the lower leg was estimated in the frequency domain with an average coherence of 0.92 within the frequency range of 0–30 Hz, showing a linear correlation between the displacement and the torques within this frequency range under the conditions of the experiment. The mean magnitude of the stiffness of the lower leg (the impedance magnitude averaged in the range of 0–1 Hz) was determined as 4.9 ± 0.74 Nm/rad. The direct estimation of the quasi-static stiffness of the lower leg results in the mean value of 5.8 ± 0.81 Nm/rad. An analysis of variance shows that the estimated values for the stiffness from the two experiments are not statistically different.

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Section: Introductionmentioning

confidence: 99%

Mechanical Impedance of the Non-loaded Lower Leg with Relaxed Muscles in the Transverse Plane

Ficanha

Ribeiro

Rastgaar

2015

Front. Bioeng. Biotechnol.

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“…The authors also show, that slipping a bio-inspired adaptive hoof requires about three times more work than slipping a comparable ball shaped foot. In rehabilitation engineering, the design of feet prostheses is a large research area and various prosthetic device featuring passive [10] and active compliance [11], [12], [13] are developed. All the active prostheses feature series and/or parallel elastics besides the powered ankle motion to allow for impact absorption and to enable a natural walking gait.…”

Section: A Related Workmentioning

confidence: 99%

Towards a Passive Adaptive Planar Foot with Ground Orientation and Contact Force Sensing for Legged Robots

Käslin

Kolvenbach

Paez

et al. 2018

2018 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

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Adapting to the ground enables stable footholds in legged locomotion by exploiting the structure of the terrain. On that account, we present a passive adaptive planar foot with three rotational degrees of freedom that is lightweight and thus suited for highly dynamic legged robots. Its low laying pivot joint provides high stability towards kinking. Information about the relative foot sole pose, and accordingly, the ground orientation is gathered by inertial measurement units (IMUs) placed on the foot sole and the shank. A complementary filter is presented that fuses these orientation estimates with an angular encoder to obtain a drift-free relative foot sole pose. The passive adaptive planar foot has been tested and compared to the classical point foot design on a variety of terrains and shows superior traction performance, especially on compressible soils. Being mounted on the quadrupedal robot ANYmal, the foot provides a reliable contact detection based on the fusion of the built-in 6-axis force/torque transducer and the IMUs. This allows to walk and trot on uneven terrain, loose soils, as well as climbing up a ramp and stairs while keeping the entire foot sole in ground contact all the time.

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“…Ficanha, Rastgaar, and Kaufman also developed a cable-driven foot mechanism capable of achieving plantarflexion and dorsiflexion, as well as inversion and eversion using tendon-like cables [49].…”

Section: Development Of a Tendon-based Actuation Schemementioning

confidence: 99%

Design and Prototyping of a Shape-Changing Rigid-Body Human Foot in Gait

Rolfe

Murray

Myszka

2018

Volume 5B: 42nd Mechanisms and Robotics Conference

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Traditional ankle-foot devices such as prostheses or robotic feet seek to replicate the physiological change in shape of the foot during gait using compliant mechanisms. In comparison, rigid-body feet tend to be simplistic and largely incapable of accurately representing the geometry of the human foot. Rigidbody mechanisms offer certain advantages over compliant mechanisms which may be desirable in the design of ankle-foot devices, including the ability to withstand greater loading, the ability to achieve more drastic shape-change, and the ability to be synthesized from their kinematics, allowing for realistic functionality without a priori characterization of the external loading conditions of the foot. This work focuses on applying the methodology of shape-changing kinematic synthesis to design and prototype a multi-segment rigid-body foot device capable of matching the dynamic change in shape of the human foot in gait.

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A two-axis cable-driven ankle-foot mechanism

Cited by 22 publications

References 21 publications

Mechanical Impedance of the Non-loaded Lower Leg with Relaxed Muscles in the Transverse Plane

Mechanical Impedance of the Non-loaded Lower Leg with Relaxed Muscles in the Transverse Plane

Towards a Passive Adaptive Planar Foot with Ground Orientation and Contact Force Sensing for Legged Robots

Design and Prototyping of a Shape-Changing Rigid-Body Human Foot in Gait

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