Unified GRF-based control for adjusting hopping frequency with various robot configurations

Mohseni, Omid; Schmidt, Patrick; Seyfarth, André; Sharbafi, Maziar Ahmad

doi:10.1080/01691864.2022.2077637

Cited by 6 publications

(3 citation statements)

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“…In order to minimize the gastrocnemius PAM's potential influences on the hopping behavior and ensure a reasonable ankle joint motion, the gastrocnemius PAM pressure was set to 0.1MPa. To prevent ankle hyper-extension in the flight phase, we added a tibialis spring stiffness and its rest length was selected based on a previous study (Mohseni et al, 2022 ). The motor control parameters and the parallel PAM rest lengths were the same as in the previous EPA-Hopper experiment.…”

Section: Resultsmentioning

confidence: 99%

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Exploring the effects of serial and parallel elasticity on a hopping robot

Zhao

Mohseni²,

Murcia³

et al. 2022

Front. Neurorobot.

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The interaction between the motor control and the morphological design of the human leg is critical for generating efficient and robust locomotion. In this paper, we focus on exploring the effects of the serial and parallel elasticity on hopping with a two-segmented robotic leg called electric-pneumatic actuation (EPA)-Hopper. EPA-Hopper uses a hybrid actuation system that combines electric motors and pneumatic artificial muscles (PAM). It provides direct access to adjust the physical compliance of the actuation system by tuning PAM pressures. We evaluate the role of the serial and parallel PAMs with different levels of compliance with respect to four criteria: efficiency, performance, stability, and robustness of hopping against perturbations. The results show that the serial PAM has a more pronounced impact than the parallel PAM on these criteria. Increasing the stiffness of the serial PAM decreases the leg stiffness of the unloading phase during hopping. The stiffer the leg, the more efficient and the less robust the movement. These findings can help us further understand the human hopping mechanism and support the design and control of legged robots and assistive devices.

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Section: Resultsmentioning

confidence: 99%

“…It also uses a spring, which imitates the tibialis muscle for the ankle dorsiflexion. A detailed description of the robot can be found in our previous study (Mohseni et al, 2022 ).…”

Section: Methodsmentioning

confidence: 99%

Exploring the effects of serial and parallel elasticity on a hopping robot

Zhao

Mohseni²,

Murcia³

et al. 2022

Front. Neurorobot.

Self Cite

View full text Add to dashboard Cite

show abstract

“…While the exact operative mechanism behind RF and HAM muscle activity remains elucidated, the stretch reflex emerges as a viable candidate. Several control models replicating stretch reflexes for robotic systems have been developed (Geyer et al, 2003;Geyer and Herr, 2010;Song and Geyer, 2015;Schumacher and Seyfarth, 2017;Kawaharazuka et al, 2020;Mohseni et al, 2022), and their potential benefits have been reported for PAM-driven robots as well (Rosendo et al, 2015;Liu et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Enhancing postural stability in a musculoskeletal hopping robot through stretch reflex application on biarticular thigh muscles

Takahashi,

Murakami,

Hosoda

2023

Front. Robot. AI

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Postural stabilization during rapid and powerful hopping actions represents a significant challenge for legged robotics. One strategy utilized by humans to negotiate this difficulty is the robust activation of biarticular thigh muscles. Guided by this physiological principle, this study aims to enhance the postural stability of a hopping robot through the emulation of this human mechanism. A legged robot powered by pneumatic artificial muscles (PAMs) was designed to mimic human anatomical structures. A critical aspect of this development was creating a tension-oriented stretch reflex system engineered to initiate muscle activation in response to perturbations. Our research encompassed three experiments: 1) assessing the trunk pitch angle with and without the integration of stretch reflexes, 2) evaluating the consistency of hops made with and without reflexes, and 3) understanding the correlation between the reflex strength equilibrium in the biarticular thigh muscles and trunk pitch angle. The results indicated that the integration of the stretch reflex minimized perturbations, thereby allowing the robot to perform double the continuous hops. As hypothesized, adjusting the reflex strength equilibrium caused a shift in the angle. This reflex mechanism offers potential application to PAM-driven robots and signifies a promising avenue for enhancing postural stability in diverse forms of locomotion, including walking and running.

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