Design of Smart Modular Variable Stiffness Actuators for Robotic-Assistive Devices

Grosu, Victor; Rodriguez–Guerrero, Carlos; Grosu, Svetlana; Vanderborght, Bram; Lefeber, Dirk

doi:10.1109/tmech.2017.2704665

Cited by 58 publications

(31 citation statements)

References 33 publications

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“…. e lo = (A e − L e C e )e lo + B le u le = (A e − L e C e )e lo + d le (19) where B le ∈ R 8×4 , u le ∈ R 4×1 , d le ∈ R 8×1 are shown in (20).…”

Section: The Linear Extended State Observer Designunclassified

“…If A e − L e C e is Hurwitz, then (19) will have BIBO stability. That is, there are ε dp ≥ 0 and ε dk ≥ 0, so that z q5 = z q5 −ẑ q5 ≤ ε dp and z k3 = |z k3 −ẑ k3 | ≤ ε dk are established.…”

Section: Assumptionmentioning

confidence: 99%

“…Including: The VSJ whose joint stiffness is varied through the combination of two antagonistic serial elastic actuators (SEAs) controlled by two separate motors [13,14]. Other realizations for stiffness altering are achieved through the principle of lever mechanism [14][15][16][17][18], or else adjusting the preload of the linear spring by a nonlinear connector between the output link and the spring element [18][19][20][21]. VSJ has many advantages, mainly in the passive adaptability, inherent flexibility, and the ability to adapt to the task needs to adjust the joint output stiffness.…”

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confidence: 99%

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Research on Angle and Stiffness Cooperative Tracking Control of VSJ of Space Manipulator Based on LESO and NSFAR Control

Hong

Dong

2019

Electronics

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With the increase in on-orbit maintenance and support requirements, the application of space manipulator is becoming more promising. However, how to control the vibration generated by the space manipulator has been a difficult problem to be solved. The advent of variable stiffness joint (VSJ) has brought about a dawn in solving this problem. But how to achieve coordinated control of joint angle and stiffness is still a problem to be solved, especially when considering system model parameter uncertainty, unknown disturbance and control input saturation. In order to realize the controllable attenuation of the vibration of the space flexible manipulator based on the variable stiffness joint, the dynamic model of the variable stiffness joint was constructed. Then the linear transformation and feedback linearization method are used to transform its complex nonlinear dynamic model system into a pseudo-linear system containing aggregate disturbance and input saturation constraints. This paper constructs a linear extended state observer (LESO) for estimating the state of unknown systems in pseudo-linear systems. Based on the idea of state feedback control, a Neural State Feedback Adaptive Robust (NSFAR) control is constructed by using Radial Basis Function Neural Network. The adaptive input saturation compensation control law is also designed by using Radial Basis Function Neural Network to deal with the input saturation compensation problem. The ultimate uniform bounded stability of the constructed system is proved by the stability analysis based on Lyapunov function. Finally, the effectiveness and superiority of the constructed tracking algorithm are verified by compared simulation and semi-physical experiment.

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“…. e lo = (A e − L e C e )e lo + B le u le = (A e − L e C e )e lo + d le (19) where B le ∈ R 8×4 , u le ∈ R 4×1 , d le ∈ R 8×1 are shown in (20).…”

Section: The Linear Extended State Observer Designunclassified

Section: Assumptionmentioning

confidence: 99%

mentioning

confidence: 99%

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Research on Angle and Stiffness Cooperative Tracking Control of VSJ of Space Manipulator Based on LESO and NSFAR Control

Hong

Dong

2019

Electronics

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“…where A depicts the network of ESAs described in (3) with parameters m = 2.94 × 10 −3 kg, k = 0.343 N/m, c = 1.75×10 −16 N · s/m . The mass of each coil is obtained by measurement.…”

Section: Numerical Testsmentioning

confidence: 99%

“…Series elastic and variable stiffness actuators (SEA/VSAs) are implemented and designed because of their ability to minimize large forces due to shocks, to safely interact with the user, and their ability to store and release energy in passive elastic elements [3]- [5]. However, they are made of intrinsically rigid components.…”

Section: Introduction Brief Literature Review Paper Contributionmentioning

confidence: 99%

Dynamic Actuator Selection and Robust State-Feedback Control of Networked Soft Actuators

Ebrahimi¹,

Nugroho²,

Taha³

et al. 2018

2018 IEEE International Conference on Robotics and Automation (ICRA)

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The design of robots that are light, soft, powerful is a grand challenge. Since they can easily adapt to dynamic environments, soft robotic systems have the potential of changing the status-quo of bulky robotics. A crucial component of soft robotics is a soft actuator that is activated by external stimuli to generate desired motions. Unfortunately, there is a lack of powerful soft actuators that operate through lightweight power sources. To that end, we recently designed a highly scalable, flexible, biocompatible Electromagnetic Soft Actuator (ESA). With ESAs, artificial muscles can be designed by integrating a network of ESAs. The main research gap addressed in this work is in the absence of system-theoretic understanding of the impact of the realtime control and actuator selection algorithms on the performance of networked soft-body actuators and ESAs. The objective of this paper is to establish a framework that guides the analysis and robust control of networked ESAs. A novel ESA is described, and a configuration of soft actuator matrix to resemble artificial muscle fiber is presented. A mathematical model which depicts the physical network is derived, considering the disturbances due to external forces and linearization errors as an integral part of this model. Then, a robust control and minimal actuator selection problem with logistic constraints and control input bounds is formulated, and tractable computational routines are proposed with numerical case studies.

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Module‐Assembled Elastomer Showing Large Strain Stiffening Capability and High Stretchability

et al. 2023

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Elastomers are indispensable materials due to their flexible, stretchable, and elastic nature. However, the polymer network structure constituting an elastomer is generally inhomogeneous, limiting the performance of the material. Here, a highly stretchable elastomer with unprecedented strain‐stiffening capability is developed based on a highly homogeneous network structure enabled by a module assembly strategy. The elastomer is synthesized by efficient end‐linking of a star‐shaped aliphatic polyester precursor with a narrow molecular‐weight distribution. The resulting product shows high strength (≈26 MPa) and remarkable stretchability (stretch ratio at break ≈1900%), as well as good fatigue resistance and notch insensitivity. Moreover, it shows extraordinary strain‐stiffening capability (>2000‐fold increase in the apparent stiffness) that exceeds the performance of any existing soft material. These unique properties are due to strain‐induced ordering of the polymer chains in a uniformly stretched network, as revealed by in situ X‐ray scattering analyses. The utility of this great strain‐stiffening capability is demonstrated by realizing a simple variable stiffness actuator for soft robotics.

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Design of Smart Modular Variable Stiffness Actuators for Robotic-Assistive Devices

Cited by 58 publications

References 33 publications

Research on Angle and Stiffness Cooperative Tracking Control of VSJ of Space Manipulator Based on LESO and NSFAR Control

Research on Angle and Stiffness Cooperative Tracking Control of VSJ of Space Manipulator Based on LESO and NSFAR Control

Dynamic Actuator Selection and Robust State-Feedback Control of Networked Soft Actuators

Module‐Assembled Elastomer Showing Large Strain Stiffening Capability and High Stretchability

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