An experimental study into displacement of a shape memory alloy actuated robotic microgripper

Llewellyn-Evans, H.; Griffiths, Christian; Fahmy, Ashraf

doi:10.1088/2631-8695/ab6d27

Cited by 9 publications

(6 citation statements)

References 34 publications

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“…The VDEHA system comprises a primary pump (2) and an auxiliary booster pump (3) that serve the purpose of providing the adjustment system with a supply of power and pre-charging the main power line (A and B). The adjustment of the swashplate angle of the main pump is achieved through the manipulation of the stroking cylinder (6), which is controlled by a solenoid-operated spool valve (5). The linear actuator's position (14) is measured using an LVDT (15) and subsequently transmitted to the NI Controller (16).…”

Section: Resultsmentioning

confidence: 99%

“…A three-phase electric motor (1) is used to drive the shaft of the main pump (2). Flow through the pump is controlled with the swashplate control mechanism and solenoid-operated spool valve (5). Since the pump is bidirectional with variable displacement, it has two delivery ports.…”

Section: Swashplate Controlled Electro-hydrostatic Actuation Systemmentioning

confidence: 99%

“…Position-controlled electrohydrostatic actuation (EHA) systems have high accuracy, quick response times, and are able to handle high forces. In addition, the EHA system is easily integrated into existing hydraulic systems, making it a cost-effective solution for a variety of industrial applications such as mobile machine [1], mining [2], excavation [3], hydraulic presses [4], robotics [5], manufacturing systems [6], and stationary systems. Conventional hydraulic systems are inefficient because of their fixed energy generation capacity, but actuators need variable energy.…”

Section: Introductionmentioning

confidence: 99%

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Position control performance analysis of linear actuator in swashplate-controlled electro hydrostatic actuation system

Kumar,

Mandal

2023

Eng. Res. Express

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The position control of an energy efficient electrohydraulic actuation system is a decisive characteristic of its performance. In position control applications, a servo valve and/or variable displacement pump are vital to control the position of the linear actuator. In this open-loop control experimental work, the position of a linear actuator having a stroke length of 0.2 m is controlled by a swashplate-controlled electro hydrostatic actuation system. LabVIEW is used to create the control algorithm, and the National Instrument compact-RIO controller is used to control the voltage supply. The National Instruments controller processes sinusoidal and square demand signals at frequencies of 1/16, 1/12, 1/8, and 1/4 Hz. Open-loop control performance is predominantly dependent on the appropriate tuning of the voltage supply. Control performance is evaluated using the parameters integrated absolute error, integrated square error, integrated time absolute error, and integrated time square error. In comparison to square demand, it has been found that sinusoidal demand offers better position control accuracy, and square demand also offers appropriate control accuracy only at lower frequencies (1/16 Hz).

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Section: Resultsmentioning

confidence: 99%

Section: Swashplate Controlled Electro-hydrostatic Actuation Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Position control performance analysis of linear actuator in swashplate-controlled electro hydrostatic actuation system

Kumar,

Mandal

2023

Eng. Res. Express

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“…For the development of an instrumented but multi-axis microgripper from the developed PRT, the primary requirement was to integrate the sensing tool with the precise multi-axis actuators (for multi DoF tasks). The actuation of any microgripper can be chosen from the different existing principles such as electrostatic [ 39 ], electromagnetic [ 40 , 41 ], pneumatic [ 42 ], electrothermal [ 43 ], vacuum [ 44 ], shape memory alloy [ 45 ] or piezoelectric [ 46 ]. One important point in the choice of the actuator is that the actuator should not interfere with the performance of the sensing device integrated; therefore, in the context of the piezoresistive tool for sensing, it is important to avoid external stimuli such as heating or optical-based actuation.…”

Section: Proposed Sensing Tool For Instrumented Microgripper Developmentmentioning

confidence: 99%

A Two-Axis Piezoresistive Force Sensing Tool for Microgripping

Tiwari

Billot

Clevy

et al. 2021

Sensors

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Force sensing has always been an important necessity in making decisions for manipulation. It becomes more appealing in the micro-scale context, especially where the surface forces become predominant. In addition, the deformations happening at the very local level are often coupled, and therefore providing multi-axis force sensing capabilities to microgripper becomes an important necessity. The manufacturing of a multi-axis instrumented microgripper comprises several levels of complexity, especially when it comes to the single wafer fabrication of a sensing and actuation mechanism. To address these requirements, in this work, an instrumented two-axis force sensing tool is proposed, which can then be integrated with the appropriate actuators for microgripping. Indeed, based on the task, the gripper design and shape requirements may differ. To cover wide needs, a versatile manufacturing strategy comprising of the separate fabrication of the passive and sensing parts was especially investigated. At the microscale, signal processing brings additional challenges, especially when we are dealing with multi-axis sensing. Therefore, a proper device, with efficient and appropriate systems and signal processing integration, is highly important. To keep these requirements in consideration, a dedicated clean-room based micro-fabrication of the devices and corresponding electronics to effectively process the signals are presented in this work. The fabricated sensing part can be assembled with wide varieties of passive parts to have different sensing tools as well as grippers. This force sensing tool is based upon the piezoresistive principle, and is experimentally demonstrated with a sensing capability up to 9 mN along the two axes with a resolution of 20 μN. The experimental results validate the measurement error within 1%. This work explains the system design, its working principle, FEM analysis, its fabrication and assembly, followed by the experimental validation of its performance. Moreover, the use of the proposed sensing tool for an instrumented gripper was also discussed and demonstrated with a micrograsping and release task.

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“…The optimization of the thermo-mechanical response of a snakelike SMA element needs a specific study of fatigue life. In this work, we propose an investigation of the functional fatigue of a symmetrical snake-like SMA element, which may be versatile in many engineering applications such as miniature robotics, gripping devices and, moving towards biomedical systems, smart surgical tools [26][27][28]. In particular, experimental tests were carried out to identify its behavior under different cyclic load levels to derive the corresponding Wöhler curve.…”

Section: Introductionmentioning

confidence: 99%

Fatigue life characterization and modeling of a Ni–Ti snake-like element for mini actuation

Nespoli¹,

Berti²,

Petrini³

et al. 2020

Smart Mater. Struct.

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The interest in the design of shape memory alloy (SMA) actuators is recently broadened thanks to their high power density and versatility. In particular, snake-like Ni-Ti actuators demonstrated high potential at the mini-and micro-scales as SMA non-conventional active elements, due to their capacity to provide significant displacements in a very limited space and over a high number of thermo-mechanical cycles. In this study, the fatigue behavior of a snake-like Ni-Ti element has been investigated to identify the Wöhler F-N curve. Moreover, a validated digital twin of the device was prepared and used to evaluate the stress distribution throughout the fatigue tests, to convert the experimental data into a Wöhler stress-life curve. The numerical description of shape memory behavior was performed through the Petrini-Bertini constitutive model, which also allowed a better insight for future shape and functional optimization of the device.

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An experimental study into displacement of a shape memory alloy actuated robotic microgripper

Cited by 9 publications

References 34 publications

Position control performance analysis of linear actuator in swashplate-controlled electro hydrostatic actuation system

Position control performance analysis of linear actuator in swashplate-controlled electro hydrostatic actuation system

A Two-Axis Piezoresistive Force Sensing Tool for Microgripping

Fatigue life characterization and modeling of a Ni–Ti snake-like element for mini actuation

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