Stiffness Control of Variable Serial Elastic Actuators: Energy Efficiency through Exploitation of Natural Dynamics

Beckerle, Philipp; Stuhlenmiller, Florian; Rinderknecht, Stephan

doi:10.3390/act6040028

Cited by 7 publications

(4 citation statements)

References 23 publications

(59 reference statements)

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“…Ratchet open (10) By incorporating the effects of both input and output, the state-space form of the discrete part becomes…”

Section: Discrete Partmentioning

confidence: 99%

“…This one is slightly different than the previous one, since it is made to couple or decouple parallel axes, which is necessary in this case, as we want to be able to decouple the spring from the output axis. This coupling is performed by a pulley (10) with a timing belt on it instead of spur gears since a belt can more easily resolve misalignment of the axes it connects.…”

Section: Constant Torque Unit With High-speed Motormentioning

confidence: 99%

“…• Series Elastic Actuators (SEA) [6][7][8][9][10][11][12]: actuators with a compliant element placed in series with the motor which modifies the speed profile of the motor and hence reduces mainly the friction-and gearing losses.…”

Section: Introductionmentioning

confidence: 99%

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Novel SPECTA Actuator to Improve Energy Recuperation and Efficiency

et al. 2022

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The current state of the art in compliant actuation has already good performance, but this is still insufficient to provide a decent autonomy for the next generation of robots. In this paper, a next step is taken to improve the efficiency of actuators by tackling and enhancing the Series-Parallel Elastic Constant Torque Actuation (SPECTA) concept, which has previously been analyzed in simulations. In this work, the efficiency is increased further by decoupling the springs and their driving parts through the use of locking mechanisms, such that the motors are not always loaded and the springs can easily store energy from both input or output. Simulations have been performed to confirm this and they also showed that, in the SPECTA concept, it is always better to use high-speed motors instead of high-torque motors, even with non-efficient gearing. In this paper, the SPECTA concept is also validated experimentally with the use of a newly built test setup. In light of the obtained results, showing an increase in efficiency for almost all working points, it can be stated that SPECTA is a promising new actuation technology that allows for an increase in energy recuperation, efficiency, and autonomy.

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“…Ratchet open (10) By incorporating the effects of both input and output, the state-space form of the discrete part becomes…”

Section: Discrete Partmentioning

confidence: 99%

Section: Constant Torque Unit With High-speed Motormentioning

confidence: 99%

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Novel SPECTA Actuator to Improve Energy Recuperation and Efficiency

et al. 2022

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“…Yet, the increased complexity, when compared with direct actuation systems, makes controlling them effectively a challenging task. Variable Stiffness Actuators are even capable of changing the stiffness of their elastic element, allowing an adaption to different conditions and possibly improving energy efficiency [6]. Variable Stiffness Actuator designs generally include mechanisms that alter the physical stiffness characteristics of the actuator or rely on impedance control to add virtual impedance [7].…”

Section: Introductionmentioning

confidence: 99%

Exploring the Just Noticeable Interaction Stiffness Differences of an Impedance-Controlled Series Elastic Actuator

Velasco-Guillen,

Schofer,

Bliek

et al. 2023

Actuators

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The integration of a passive elastic element in series between a motor and its load is popular in many human–robot interaction scenarios. By virtually imposing elastic behavior on the motor, an impedance control can act as a second stiffness to such an actuator. In this study, we investigated how participants perceived the different stiffness settings in a series elastic actuator by measuring the Just Noticeable Difference (JND) of the real stiffness of the elastic element and the virtual stiffness introduced by impedance control. We conducted a user study during which participants interacted with an impedance-controlled Series Elastic Actuator through a lever. During the user study, we varied the real stiffness of the elastic element and the virtual stiffness. We found that participants seem to perceive both the virtual stiffness and the real stiffness in the same way and in accordance to Weber’s law, which states that the stiffness JND is always equal to a fraction of the initial stiffness. Following these findings, we concluded that the impedance controller can implement an effective virtual stiffness with a behavior comparable to a real torsional spring. Therefore, a system combining real and virtual stiffness can simulate a single combined stiffness for a user interacting with it.

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Elastic-bound conditions for energetically optimal elasticity and their implications for biomimetic propulsion systems

Pons

Beatus

2022

Nonlinear Dyn

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Stiffness Control of Variable Serial Elastic Actuators: Energy Efficiency through Exploitation of Natural Dynamics

Cited by 7 publications

References 23 publications

Novel SPECTA Actuator to Improve Energy Recuperation and Efficiency

Novel SPECTA Actuator to Improve Energy Recuperation and Efficiency

Exploring the Just Noticeable Interaction Stiffness Differences of an Impedance-Controlled Series Elastic Actuator

Elastic-bound conditions for energetically optimal elasticity and their implications for biomimetic propulsion systems

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