Evaluating Energy Consumption of an Active Magnetorheological Knee Prosthesis

Andrade, Rafhael M.; Filho, Antônio Bento; Vimieiro, Claysson Bruno Santos; Pinotti, Marcos

doi:10.1109/icar46387.2019.8981642

Cited by 17 publications

(10 citation statements)

References 23 publications

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“…The AMRK is composed by a motor unit (EC motor, harmonic drive, and MR clutch), responsible for generating positive work, that works in parallel to a MR brake, used to dissipate energy when the knee is subjected to negative work conditions. The proposed configuration is designed to perform a proper walk with low energy consumption [25,26]. The thermal model for the components of the MR actuator was presented.…”

Section: Final Remarksmentioning

confidence: 99%

“…Due to these characteristics, MR fluids are used to develop devices for many applications in engineering and industry: vehicle suspensions [18], clutches [19], brakes [20], structural vibration damping [21], intelligent prosthesis [5,[22][23][24] and others. MR devices usually present low energy consumption and high torque-to-weight ratio [25,26], which is important to increase the energy efficiency and reduce the weight of prostheses and exoskeletons' actuators [27].…”

Section: Introductionmentioning

confidence: 99%

“…The actuator employs a motor-unit (MU), composed by an EC 60 flat motor (Maxon Motors, Switzerland), harmonic drive CSG-14-100-2a (Harmonic Drive AG, Germany) and MR clutch, that works in parallel to a MR Brake. With this configuration the actuator has multifunctional working conditions and can reproduce movements similar to a healthy knee with low energy consumption [25,26]. The system is assembled in a lightweight and compact structure and can be used as a prosthetic knee, a knee actuator for exoskeletons and in robotic functions [30].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Transient Thermal Analysis of a Magnetorheological Knee for Prostheses and Exoskeletons during Over-Ground Walking

Andrade¹,

Storch²,

Paulo³

et al. 2021

Heat Transfer - Design, Experimentation and Applications

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Proper knee movement is essential for accomplishing the mobility daily tasks such as walking, get up from a chair and going up and down stairs. Although the technological advances in active knee actuators for prostheses and exoskeletons to help impaired people in the last decade, they still present several usage limitations such as overweight or limited mechanical power and torque. To address such limitations, we developed the Active Magnetorheological Knee (AMRK) that comprises a Motor Unit (MU), which is a motor-reducer (EC motor and Harmonic Drive) and a MR clutch, that works in parallel to a magnetorheological (MR) brake. Magnetorheological fluids, employed in the MR clutch and brake, are smart materials that have their rheological properties controlled by an induced magnetic field and have been used for different purposes. With this configuration the actuator can work as a motor, clutch or brake and can perform similar movements than a healthy knee. However, the stability, control, and life of magnetorheological fluids critically depend on the working temperature. By reaching a certain temperature limit, the fluid additives quickly deteriorate, leading to irreversible changes of the MR fluid. In this study, we perform a transient thermal analysis of the AMRK, when it is used for walking over-ground, to access possible fluid degradation and user’s discomfort due overheating. The resulting shear stress in the MR clutch and brake generates heat, increasing the fluid temperature during the operation. However, to avoid overheating, we proposed a mode of operation for over-ground walking aiming to minimize the heat generation on the MR clutch and brake. Other heat sources inside the actuator are the coils, which generate the magnetic fields for the MR fluid, bearings, EC motor and harmonic drive. Results show that the MR fluid of the brake can reach up to 31°C after a 6.0 km walk, so the AMRK can be used for the proposed function without risks of fluid degradation or discomfort for the user.

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Section: Final Remarksmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Transient Thermal Analysis of a Magnetorheological Knee for Prostheses and Exoskeletons during Over-Ground Walking

Andrade¹,

Storch²,

Paulo³

et al. 2021

Heat Transfer - Design, Experimentation and Applications

Self Cite

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show abstract

“…Reduced energy consumption requires lighter and smaller battery, thereby resulting in a lighter prosthesis. However, the power consumption in active prosthesis is related to the type of prosthesis, operating mode, test protocol and the subject weight, which can substantially differ among prototypes (Andrade et al, 2019a). For example, Martinez-Villalpando and Herr (2009), designed a prosthesis that uses two series elastic actuators (SEAs) with variable impedance control.…”

Section: Introductionmentioning

confidence: 99%

Novel active magnetorheological knee prosthesis presents low energy consumption during ground walking

Andrade

Martins

Pinotti

et al. 2021

Journal of Intelligent Material Systems and Structures

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This study analyses the energy consumption of an active magnetorheological knee (AMRK) actuator that was designed for transfemoral prostheses. The system was developed as an operational motor unit (MU), which consists of an EC motor, a harmonic drive and a magnetorheological (MR) clutch, that operates in parallel with an MR brake. The dynamic models of the MR brake and MU were used to simulate the system’s energetic expenditure during over-ground walking under three different working conditions: using the complete AMRK; using just its motor-reducer, to operate as a common active knee prosthesis (CAKP), and using just the MR brake, to operate as a common semi-active knee prosthesis (CSAKP). The results are used to compare the MR devices power consumptions with that of the motor-reducer. As previously hypothesized, to use the MR brake in the swing phase is more energetically efficient than using the motor-reducer to drive the joint. Even if using the motor-reducer in regenerative braking mode during the stance phase, the differences in power consumption among the systems are remarkable. The AMRK expended 16.3 J during a gait cycle, which was 1.6 times less than the energy expenditure of the CAKP (26.6 J), whereas the CSAKP required just 6.0 J.

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“…In order to improve the safety, adaptability, and interaction with the environment of mechanical joints, compliant elements have been introduced to lower-limb assistive devices, composing the Series Elastic Actuators (SEAs). SEAs have the ability to tolerate impacts where the external forces are filtered and attenuated by the elastic component [6], and to passively store mechanical energy during ground-walking and other greater dissipative activities, thereby reducing damages and energy consumption of the prosthesis if it is wisely designed [3,[7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Biomimetic Design of a Planar Torsional Spring to an Active Knee Prosthesis Actuator Using FEM Analysis

Fiorezi

Moraes

Ulhoa

et al. 2020

The 1st International Electronic Conference on Actuator Technology: Materials, Devices and Applications

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Evaluating Energy Consumption of an Active Magnetorheological Knee Prosthesis

Cited by 17 publications

References 23 publications

Transient Thermal Analysis of a Magnetorheological Knee for Prostheses and Exoskeletons during Over-Ground Walking

Transient Thermal Analysis of a Magnetorheological Knee for Prostheses and Exoskeletons during Over-Ground Walking

Novel active magnetorheological knee prosthesis presents low energy consumption during ground walking

Biomimetic Design of a Planar Torsional Spring to an Active Knee Prosthesis Actuator Using FEM Analysis

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