Design of asymmetric flexible micro-gripper mechanism based on flexure hinges

Abstract

Symmetric micro-gripper mechanism is very easy way to destroy the micro-components or parts for nonuniform force in the processing of micro-assembly. Aiming at the requirements of micro-assembly for the microtubule (diameter of 0-200 mm) components, a new type of asymmetric flexible micro-gripper mechanism based on flexure hinges was designed and studied. The asymmetric micro-gripper mechanism was driven by piezoelectric actuator, whose output displacement was amplified and transmitted by flexure hinges, and the flexible parallel four-bar mechanism was used to ensure that the micro-clamp moves and is held parallel. The displacement amplification ratio of the asymmetric flexible micro-gripper mechanism was deduced theoretically, and the finite element analysis and the experiment were also carried out to study the displacement amplification ratio in detail. The experiment results show that the displacement amplification ratio of the asymmetric flexible micro-gripper mechanism is 4.16, compared with the finite element analysis result and the theoretical calculation result; the error between them is 1.89% and 5.67%, respectively. The experiment results also show that the step-wise resolution of the micro-gripper is 7.50 mm, and the output force of the right micro-clamp was measured at 0.28 N. The asymmetric flexible micro-gripper mechanism is able to perform the micro-assembly tasks for the microtubule parts, and it is helpful to design this type of micro-gripper mechanism.

Displacement amplification ratio modeling of bridge-type nano-positioners with input displacement loss

“…6, where the displacement amplification ratio of the bridge-type mechanism is also obtained and compared with existing results in the literature, as shown in Table 2. It is clearly seen that the model proposed in the present work can more accurately describe the mechanism amplification ratio of the bridge-type mechanism, compared with representative results such as Ma et al (2006); Ye et al (2011) and Qi et al (2015), thanks to the consideration of the input displacement loss. The importance of considering the input displacement loss can also be seen from the comparison of Eqs.…”

“…The material of the nanopositioner is aluminum alloy Al-7075. Ma et al (2006) 7.18 7.95 % Model in Ye et al (2011) 7.55 3.21 % Model in Qi et al (2015) 8.20 5.13 % FEA result 7.80…”

“…It should be pointed out that the direct output displacement of a piezoelectric actuator is about one thousandth of its own length, which usually can not meet the requirements of large working range in most cases. Amplifying mechanism is typically employed to amplify and transmit displacement, such as lever mechanism (Xing, 2015;Tang and Li, 2015;Tang et al, 2018), Scott-Russell mechanism (Tian et al, 2009), rhombic mechanism (Ling et al, 2018), bridge-type mechanism (Li and Xu, 2011;Chen et al, 2018;Clark et al, 2018). Among various amplifying mecha-nisms, bridge-type mechanism was widely investigated due to its characteristics of high amplification ratio, compact structure and easy processing.…”

“…Ma et al (2006) considered the deformation of the hinge and derived the theoretical displacement amplification ratio of the bridge-type mechanism based on the kinematics theory and the virtual displacement theorem. Ye et al (2011) used the full symmetry of the bridge-type mechanism to establish a quarter model of the mechanism, and used the flexibility matrix method to derive the amplification ratio formula. Qi et al (2015) analyzed the deformation of the hinge and derived the displacement amplification model of the bridge-type mecha- nism based on the elastic beam theory.…”

Microgripper design and evaluation for automated µ-wire assembly: a survey

“…Another common shape is flexible leaf hinge which is capable of producing large displacements of the jaw tip, along with a reduced experienced stress along each hinge due to the larger area of where the stress is dispersed. However, due to the lack of circular rotation, the accuracy of the system decreases (Qingsong 2015;Beyeler et al 2007;Qu et al 2017). The advantages of the flexible leaf hinge do not however justify its use as the most important required feature is the accuracy.…”