Torque-Sensorless Control for a Powered Exoskeleton Using Highly Back-Drivable Actuators

Kanai, Yoshiki; Fujimoto, Yasutaka

doi:10.1109/iecon.2018.8591255

Cited by 10 publications

(7 citation statements)

References 14 publications

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“…Based on the basic driving efficiency in Section III-B and the direction of the power flow above, we now correct (55) to account for loss of power and friction between the driving and driven gears. The driven force decreases in proportion to the basic driving efficiency, as shown in (50). For example, when tangential force exerted by the driving gear S to the driven gear P1 is f sp1 , the reactive tangential force received by P1 becomes η a f sp1 , where η a is the basic efficiency between S and P1.…”

Section: B Driving Efficiency 1) Driving Efficiency and Tangential Fmentioning

confidence: 99%

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Bilateral Drive Gear—A Highly Backdrivable Reduction Gearbox for Robotic Actuators

Matsuki

Nagano

Fujimoto

2019

IEEE/ASME Trans. Mechatron.

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For safety purposes, cooperative robots are installed with an actuator composed of a low-power servo motor, a reduction gearbox, and a torque sensor. When cooperative robots make contact with humans or the environment, they must detect the contact force with a force sensor, a contact sensor, or a joint torque sensor. Equipping these sensors increases the cost and size of the application, but can be avoided under sufficient backdrivability of the actuator. To this end, we propose a method that maximizes the power transmission efficiency of the 3K planetary reduction gearbox and develop a prototype of the backdrivable reduction gearbox called the bilateral drive gear. For this maximization, the profile shift coefficients and the number of teeth are decided under some conditions. The forward-and backward-driving efficiencies of the prototype gearbox were 89.0% and 85.3%, respectively, and the reverse-drive starting torque was 0.020 N•m. The drive efficiency of the same gearbox with uncorrected teeth is 68.5%. The forward-driving efficiency was 20.5% higher than the nonoptimized one. We confirmed that prototype gearboxes with different gear ratios are easily backdrivable by hand.

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Section: B Driving Efficiency 1) Driving Efficiency and Tangential Fmentioning

confidence: 99%

“…As the benefits of this bilateral drive gear, sensorless torque control for a powered exoskeleton has been proposed [50]. In this article, the bilateral drive gear with a reduction ratio of 1/102.1 has been used.…”

Section: A Performance Of the Prototype Gearboxmentioning

confidence: 99%

Bilateral Drive Gear—A Highly Backdrivable Reduction Gearbox for Robotic Actuators

Matsuki

Nagano

Fujimoto

2019

IEEE/ASME Trans. Mechatron.

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“…The FUJILAB in Yokohama proposed in Fujimoto ( 2015 ) a highly backdrivable gearbox for robotics, which would be particularly suited for operation without need for a torque sensor (Kanai and Fujimoto, 2018 ).…”

Section: Review Of Emerging Transmission Technologies For Roboticsmentioning

confidence: 99%

“…With this topology, Fujimoto et al were able to reach, for a 1:102 gear ratio, forward efficiencies of 89.9% and backdriving efficiencies of 89.2%. The No-Load Starting torque in backdriving direction amounted to 0.016 Nm in a gearbox with an outer diameter of ~ Φ50 mm (Kanai and Fujimoto, 2018 ). The strategy followed to reach such high efficiencies with a Wolfrom topology consists on the optimization of the profile-shift coefficients (Fujimoto and Kobuse, 2017 ).…”

Section: Review Of Emerging Transmission Technologies For Roboticsmentioning

confidence: 99%

Compact Gearboxes for Modern Robotics: A Review

et al. 2020

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On the eve of Human-Robot-Interaction (HRI) becoming customary in our lives, the performance of HRI robotic devices remains strongly conditioned by their gearboxes. In most industrial robots, two relatively unconventional transmission technologies-Harmonic Drives © and Cycloid Drives-are usually found, which are not so broadly used in other industries. Understanding the origin of this singularity provides valuable insights in the search for suitable, future robotic transmission technologies. In this paper we propose an assessment framework strongly conditioned by HRI applications, and we use it to review the performance of conventional and emerging robotic gearbox technologies, for which the design criterion is strongly shifted toward aspects like weight and efficiency. The framework proposes to use virtual power as a suitable way to assess the inherent limitations of a gearbox technologies to achieve high efficiencies. This paper complements the existing research dealing with the complex interaction between gearbox technologies and the actuators, with a new gearbox-centered perspective particularly focused on HRI applications.

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“…However, the commonly used harmonic drive has many disadvantages, such as low efficiency and stiffness, large speed and torque fluctuations, and complex hysteresis characteristics [1] to [3], which directly affect the control precision of collaborative robots. To overcome the limitations of the harmonic drive, many researchers have recently started to study the 3K planetary joint reducer with high efficiency and stiffness to meet the high-precision force/position control requirements of collaborative robots [1] and [4] to [6]. However, these studies mainly focus on efficiency optimization design and less on the research of instantaneous efficiency characteristics.…”

Section: Introductionmentioning

confidence: 99%

A New Calculation Method for Instantaneous Efficiency and Torque Fluctuation of Spur Gears

Tian,

Wang,

Jiang

2024

sv-jme

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As a critical component of the joint gearbox, spur gear pairs play a crucial role in energy conversion, limiting the performance of a collaborative robot. Accurately assessing their instantaneous efficiency and torque fluctuation is essential for developing high-precision robot joint control models. This study proposes a computational model to predict the instantaneous efficiency and torque fluctuation of spur gears under typical operating conditions. The model incorporates a torque balance model, a load distribution model, and a friction model to reflect the relationship between gear meshing position and efficiency. The instantaneous efficiency and torque fluctuation of gear pairs were compared with the Coulomb friction model with an average friction coefficient and the elastohydrodynamic lubrication model with a time-varying friction coefficient. The effect of gear contact ratio on efficiency is analysed, while the instantaneous efficiency and torque fluctuation of gears are studied under varying operating conditions. The results indicate a maximum efficiency difference of 1.86 % between the two friction coefficient models. Under specific operating conditions, the instantaneous efficiency variation of the gear pair can reach 3.34 %, and the torque fluctuation can reach 5.19 Nm. Finally, this study demonstrates the effectiveness and accuracy of the proposed method through comparative analysis.

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Torque-Sensorless Control for a Powered Exoskeleton Using Highly Back-Drivable Actuators

Cited by 10 publications

References 14 publications

Bilateral Drive Gear—A Highly Backdrivable Reduction Gearbox for Robotic Actuators

Bilateral Drive Gear—A Highly Backdrivable Reduction Gearbox for Robotic Actuators

Compact Gearboxes for Modern Robotics: A Review

A New Calculation Method for Instantaneous Efficiency and Torque Fluctuation of Spur Gears

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