Leveraging Natural Load Dynamics With Variable Gear-Ratio Actuators

Girard, Alexandre; Asada, H. Harry

doi:10.1109/lra.2017.2651946

Cited by 13 publications

(8 citation statements)

References 16 publications

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“…11 shows the proposed hierarchical control architecture for a DSDM actuator. This paper discusses the actuatorlevel control laws coordinating motors during a shift process; the high-level robot controller was discussed in a previous publication [15]. The idea is to encapsulate DSDM actuators with simple control inputs: a desired motor torque τ d and a desired discrete operating mode k d , like a semi-automatic transmission in a car.…”

Section: Nullspace Of the Dsdm During High-speed Modementioning

confidence: 99%

A Fast Gear-Shifting Actuator for Robotic Tasks with Contacts

Girard¹,

Asada²

2022

Preprint

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Vehicle power-trains use a variable transmission (multiple gear-ratios) to minimize motor size and maximize efficiency while meeting a wide-range of operating points. Robots could similarly benefit from variable transmission to save weight and improve energy efficiency; leading to potentially groundbreaking improvements for mobile and wearable robotic systems. However, variable transmissions in a robotic context leads to new challenges regarding the gear-shifting methodology: 1) order-of-magnitude variations of reduction ratios are desired, and 2) contact situations during manipulation/locomotion tasks lead to impulsive behavior at the moment when gear-shifting is required. This paper present an actuator with a gear-shifting methodology that can seamlessly change between two very different reduction ratios during dynamic contact situations. Experimental results demonstrate the ability to execute a gear-shift from a 1:23 reduction to a 1:474 reduction in less than 30ms during contact with a rigid object.

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Section: Nullspace Of the Dsdm During High-speed Modementioning

confidence: 99%

A Fast Gear-Shifting Actuator for Robotic Tasks with Contacts

Girard¹,

Asada²

2022

Preprint

Self Cite

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“…The transmission ratio has a demonstrated strong influence on the performance of a robotic system. This explains its preferent role in the literature dedicated to robotic actuation optimization, and the growing interest of roboticists in the possibilities to use variable transmissions (Kim et al, 2002 ; Carbone et al, 2004 ; Stramigioli et al, 2008 ; Girard and Asada, 2017 ). Although we are convinced that variable transmissions are very promising and will certainly contribute to shape the future robotics landscape, we have restricted our analysis here to constant-ratio compact gearboxes.…”

Section: An Hri-enhanced Assessment Framework For Robotic Transmissimentioning

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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“…More recently, Girard and Asada (2015) presented a similar actuator where the worm gears were replaced by controllable brakes. For this actuator, they developed several control strategies to divide the required power over the motors and to deal with the holding brakes (Girard and Asada, 2016, 2017). Much work has also been done on impedance control (Nagai et al, 2009).…”

Section: Types Of Redundant Actuatorsmentioning

confidence: 99%

Kinematically redundant actuators, a solution for conflicting torque–speed requirements

Verstraten

Furnémont

López-García

et al. 2019

The International Journal of Robotics Research

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Robots often switch from highly dynamic motion to delivering high torques at low speeds. The actuation requirements for these two regimes are very different. As a consequence, the average efficiency of the actuators is typically much lower than the efficiency at the optimal working point. A potential solution is to use multiple motors for a single motor joint. This results in a redundant degree of freedom, which can be exploited to make the system more efficient overall. In this work, we explore the potential of kinematically redundant actuators in dynamic applications. The potential of a kinematically redundant actuator with two motors is evaluated against a single-motor equivalent in terms of operating range, maximum acceleration, and energy consumption. We discuss how the comparison is influenced by the design of the actuator and the way how the power is distributed over the input motors. Our results support the idea that kinematically redundant actuators can resolve the conflicting torque–speed requirements typical of robots.

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Leveraging Natural Load Dynamics With Variable Gear-Ratio Actuators

Cited by 13 publications

References 16 publications

A Fast Gear-Shifting Actuator for Robotic Tasks with Contacts

A Fast Gear-Shifting Actuator for Robotic Tasks with Contacts

Compact Gearboxes for Modern Robotics: A Review

Kinematically redundant actuators, a solution for conflicting torque–speed requirements

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