Variational nonlocal gradient elasticity for nano-beams

Stick-slip piezoelectric actuators have been widely employed in those fields where both large working stroke and high positioning accuracy are required. However, the problems of backward motion and relatively low load capability limit their applications, and these two problems are usually contradictory. Attempted to solve these two problems at the same time, in this study, a composite flexible hinge was designed to actively control the contact force between the driving foot and the slider of a stick-slip piezo-driven linear actuator. To confirm the validity, a prototype actuator was designed and fabricated. The dimensions of the actuator in X, Y and Z directions are about 80 mm, 60 mm and 20 mm, respectively. The output characteristics of the actuator were evaluated by experiments. The results showed that without the active control of the contact force, the maximum speed being free of external load were 1.39 and 2.18 mm/s when the driving frequencies were 100 and 200 Hz, respectively. Correspondingly, the maximum horizontal loads of the actuator were 25 g and 50 g, respectively. However, with the active control of the contact force, the maximum speed were 1.74 and 4.1 mm/s under the driving frequency of 100 and 370 Hz, respectively. Moreover, the maximum horizontal loads under 100 Hz and 200 Hz were improved to be 40 g and 70 g, respectively.

Actively controlling the contact force of a stick-slip piezoelectric linear actuator by a composite flexible hinge

Aiming to simulate the experimentally observed three kinds of one-stepping characteristics in stick-slip piezoelectric actuators, i.e., backward motion, smooth motion, and sudden jump, a new dynamic model is proposed with consideration of the deformation of overall system. Being different from the existing dynamic models that consider the overall system as a rigid body, the stiffness coefficient and damping coefficient of the overall system are introduced in the newly proposed model. By adjusting the parameters according to the experimental conditions, these three kinds of characteristics are successfully simulated for the first time in this field. By comparison with the existing dynamic models of stick-slip piezoelectric actuators, the effectiveness, advancement, and necessity of the proposed dynamic model are demonstrated. This model is expected to be helpful for the structure design and performance prediction of stick-slip piezoelectric actuators.

A Dynamic Model of Stick-Slip Piezoelectric Actuators Considering the Deformation of Overall System

A broadband magnetically coupled bistable energy harvester via parametric excitation

In the field of piezoelectric actuators, high speed piezoelectric stick-slip actuators have received considerable attention. A linear stick-slip piezoelectric actuator is proposed in this article, which combines asymmetric flexure hinge with triangular displacement amplification mechanism. The designed linear piezoelectric stick-slip actuator can achieve high speed at lower frequency. The configuration of the actuator and driving principle are illustrated and designed by theory and simulation. In order to study its performance, a prototype is fabricated, and an experimental system is established. The experimental results confirm that the maximum step efficiency of the prototype is 97.9 %. The maximum speed is 20.17 mm/s under the driving voltage of 100 V
 P-P
, the driving frequency of 610 Hz and the locking force of 2.5 N. The maximum load capacity is 2.4 N under the locking force of 3.5 N. The proposed piezoelectric stick-slip actuator increases the step efficiency and improves the output speed at lower frequency.

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A Linear Piezoelectric Stick-Slip Actuator via Triangular Displacement Amplification Mechanism

Stick-slip piezoelectric actautors are promising actautors with prinicipally unlimited stroke and positioning resolution. However, it is challenged with a low load capacity, which limits the field of application. Various types of compliant driving foot were proposed in literature to improve the load capacity but the improved load capacity is direction-dependent. To improve the load capacity in both forward and backward directions, this paper proposes an approach via a shared driving foot. The basic idea is to employ two piezoelectric actuators and a shared driving foot to work in a way that either forward or backward driving is a stick-slip process and both involve a clamping action during the 'stick' phase and a releasing action during the 'slip' phase, so that a large driving force/load capacity can be achieved in both driving directions. Following this approach, a shared driving foot was proposed and designed. Finite element simulations were carried out and have validated that the designed driving foot can realize the proposed approach as desired. A prototype was built and tested and the effectiveness of the proposed approach has been validated by experiments. Under the sawtooth waveform voltage of 100 V at 1 kHz, the prototype achieved a free-load forward and backward driving speed as large as 18.6 mm s−1 and 16 mm s−1 respectively and a load capacity larger than 2 kg for both driving directions. Under a driving load of 2 kg, it can still move stably with forward and backward driving speeds of 1.8 mm s−1 and 0.6 mm s−1 respectively.

https://iopscience.iop.org/article/10.1088/1361-665X/ab1428/pdf

Yimin Fan

Papers

A broadband magnetically coupled bistable energy harvester via parametric excitation

Improving load capacity of stick-slip actuators in both driving directions via a shared driving foot

Enhanced nonlinear energy harvesting using combined primary and parametric resonances: Experiments with theoretical verifications

Design, development, and theoretical and experimental tests of a nonlinear energy harvester via piezoelectric arrays and motion limiters

An investigation of piezoelectric actuator high speed operation for self-sensing