Design of a variable stiffness actuator using shape memory alloy wire

Nalini, D.; Ruth, D. Josephine Selvarani; Dhanalakshmi, K.

doi:10.1109/poweri.2016.8077234

Cited by 9 publications

(5 citation statements)

References 12 publications

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“…Table 6 provides a comprehensive comparison of the LDVSA with several existing continuous, SMA-based and discrete VSAs (or joints). As shown in Table 6, except for the three VSAs [29], [30] and PVDF-VSJ [31] with extremely small load capacity (MFoT), the actuator volume (size) of the LDVSA (VoA) is the smallest. Although the weight of the LDVSA (WoA) is not competitive, its power-weight ratio (PoA/WoA) is satisfactory, and its weight and volume (size) can be further greatly reduced according to actual stroke and load-bearing requirements.…”

Section: Performance Tests and Comparison A Stiffness Verificationmentioning

confidence: 99%

“…Due to the remarkable properties of SMA such as high force-weight ratio, high strain capability, corrosion resistance, light weight, silent, compact and simple design, a passive bias type SMA-based VSA [29] and an active differential bias type SMA-based VSA [30] use SMA wires to achieve both stiffness and output side adjustments with small volume and weight. However, the narrow stiffness adjustment range, unidirectional actuation, and small load capacity of the SMA wires severely limit their practicality.…”

Section: Namementioning

confidence: 99%

“…Its stiffness adjustment range is small, and two motors also increase the complexity (control and compactness) of the actuator. [29] proposes a linear variable stiffness actuator, in which a pair of SMA wires and a compressive spring are configured in parallel. The SMA spring's stiffness is changed by the current supplied to it.…”

Section: Introductionmentioning

confidence: 99%

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Design and Analysis of a Linear Digital Variable Stiffness Actuator

Guo

Sun

et al. 2021

IEEE Access

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Section: Performance Tests and Comparison A Stiffness Verificationmentioning

confidence: 99%

Section: Namementioning

confidence: 99%

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Design and Analysis of a Linear Digital Variable Stiffness Actuator

Guo

Sun

et al. 2021

IEEE Access

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“…The relation between the minimum actuating temperature, captured via infrared images, and safe heating current and the temperature of the SMA wire is shown in Figure 9(a) and (b), respectively. The actuator response is obtained for 425 mA, 0.5 Hz sine input to depict the operation during cycling of heating and cooling phases, as shown in Figure 10, for both the operational modes (Nalini D. et al, 2016a and2016b). The responses of the VSLA for both the operating modes, corresponding to the range of activation, are presented as plots in Figure 11.…”

Section: Basic Performancementioning

confidence: 99%

Synergistically configured shape memory alloy for variable stiffness translational actuation

Nalini

Dhanalakshmi

2019

Journal of Intelligent Material Systems and Structures

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The structural composition of two elastic elements, shape memory alloy wire (active actuating element) and spring (the passive bias), offers variable stiffness actuation. Based on this principle, a variable stiffness linear actuator is conceptually designed and developed. It is electromechanical by nature, that is, it is electrically activated and creates translational/linear motion. The variable stiffness linear actuator engages shape memory alloy wire(s) along with a passive compression spring to work synergistically. The biasing element offers recovery force to the shape memory alloy wire as well as compliance to the whole structure. The synergistic configuration exhibits an aiding force, thereby allowing an actuation with large displacement and a wide range of stiffness. The actuator mechanism is implemented through parallel action and further proposes two different modes of operation: pull mode (i.e. the disc moving along a fixed shaft) and push mode (i.e. linear reciprocating motion of the pushrod). The shape memory alloy configured actuator mechanism is analysed theoretically; the working model of the variable stiffness linear actuator is developed and investigated experimentally. The results apprise that the variable stiffness linear actuator is capable of offering large displacement and in reproducing the stiffness profile for active compliance control applications.

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“…For instance, Guo et al [34] designed a novel compliant differential SMA actuator with two antagonistic SMA wires and a torsion spring, which can realize a higher response and a larger output angle than conventional differential SMA actuators [35]. To improve the displacement and stiffness range, Nalini et al proposed the synergistic SMA actuator that used multiple sets of SMA wires and springs in a synergistic arrangement [36]. In addition, the authors also designed a variable stiffness linear actuator (VSLA) with a parallel arrangement of SMA and bias (reset) elements [37], which can realize the precise control of its inherent flexibility and active flexibility.…”

Section: Introductionmentioning

confidence: 99%

Design and experiment of a SMA-based continuous-stiffness-adjustment torsional elastic component for variable stiffness actuators

Xiong¹,

Sun²,

Jia³

et al. 2021

Smart Mater. Struct.

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The variable stiffness actuator (VSA) is widely applied in robotics and human-robot interactions, generating controllable torque with sufficient compliance to ensure safety and robustness. At present, typical VSA design usually adopted pure mechanical structures that integrated an additional motor for stiffness adjustment, making it hard to meet the demand of lightweight joint actuation due to large actuator size and weight. As a new functional material, shape memory alloy (SMA) shows the prospect of lightweight actuation due to its high power-to-weight ratio. In this paper, a compact SMA-based torsional elastic component (SMA-TE) for the VSA is proposed. The SMA-TE with torsional stiffness is implemented by the confrontational arrangement of paired spiral SMA springs. The ceramic heating plate and semiconductor refrigeration plate are installed in the elastic component shell, and the thermally conductive medium is filled between the internal gap. The torsional stiffness of the SMA-TE can be continuously adjusted via a feed-forward cascade controller. Repeated experimental results show that the SMA-TE can precisely maintain constant stiffness and continuously adjust its stiffness between 2.6 Nm rad −1 and 6.8 Nm rad −1 when performing precise square wave stiffness tracking under variable frequencies.

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Design of a variable stiffness actuator using shape memory alloy wire

Cited by 9 publications

References 12 publications

Design and Analysis of a Linear Digital Variable Stiffness Actuator

Design and Analysis of a Linear Digital Variable Stiffness Actuator

Synergistically configured shape memory alloy for variable stiffness translational actuation

Design and experiment of a SMA-based continuous-stiffness-adjustment torsional elastic component for variable stiffness actuators

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