With simple structure and control, impact inertial piezoelectric actuators are one promising type for precision positioning with large working stroke and high resolution. However, their applications still face some challenges, especially the incompatibility between speed and resolution as well as the motion instability due to the overturning moment. Therefore, innovative design of impact inertial actuators is urgently required. In this article, by designing an asymmetric compliant mechanism with a thick end and a thin end to generate asymmetric friction between the driving feet and U-groove, a novel impact inertial piezoelectric actuator was proposed. Its structure design, working principle, and output performances were addressed in detail. The results indicated that the thick end and thin end had quite different stepping characteristics, and the ideal stepping characteristic with quite small backward motion was achieved at the thick end. The displacement-time curves confirmed the motion stability of the actuator for bidirectional motions, and the small difference in forward and reverse speeds was explored. This actuator achieved the maximum speed of 7311 μ m/s, the resolution of 221 nm, vertical and horizontal loading capacities being over 20 N and 1.4 N, respectively. Performance comparison with some previous impact inertial actuators further demonstrated the advancement.

Backward motion commonly exists in the stick-slip linear piezoelectric actuator, resulting in deterioration of the output performance and limiting their applications. To solve the problem, a stick-slip linear piezoelectric actuator with suppressed backward motion, achieved using an active-locking mechanism (ALM) with two mechanisms, is proposed in this paper. One mechanism involves stick-slip driving, while the other actively suppresses backward motion by clamping the slider during the backward driving process through efficient control. A prototype actuator was designed and manufactured to verify the feasibility of this method, and an experimental system was established to obtain the detailed parameters. Also, to verify the feasibility and effectiveness of the suppression effect on backward motion of the proposed actuator, the output performance of the traditional stick-slip actuator and the actuator with the ALM were compared. Based on the results, we demonstrate that the maximum output speed and maximum output force of the prototype are 2.26 mm s ⁻¹ and 1.6 N under a voltage of 100 V, respectively.

Motion speed is an important parameter of stick-slip piezoelectric actuators. However, most of the existing stick-slip piezoelectric actuators achieve a high motion speed by operating under a quite high driving frequency. Operation under high frequency will affect the motion stability and as well accelerate the wear of the contact surfaces. To realize relatively high speed under a relatively low operation frequency, here a specific L-shape flexure hinge was employed to design the stick-slip piezoelectric actuator. Its structure design, working principle and processes, structure parameter selection, and output performances were studied in detail. The experimental results indicated that the designed actuator could achieve a maximum motion speed of 16.67 mm s ⁻¹ under the driving frequency of 800 Hz. This operation frequency was much lower than those employed in previous actuators for achieving a similar motion speed. By comparative analysis, it was shown that the designed actuator also maintained good minimum stepping displacement and loading capacity. These features would be useful for the practical applications of stick-slip piezoelectric actuators.

Stick-slip piezoelectric actuators are favored by precision instruments owing to their high resolution, fast response, etc. However, they face challenges when it comes to achieving effective output of the actuators with small mass rotor due to the offset of the forward angle by the backward angle. Aiming to achieve stable and effective stick-slip motion, a method that employs auxiliary friction was proposed, and accordingly, a stick-slip actuator was designed. Then, the feasibility of the auxiliary friction method was proved by comparing the theoretical analysis results of the output performances for the actuator with and without auxiliary friction. An experimental prototype with the rotor mass of 2 g was developed to test its output performances. Under 10 Hz and 100 V, the actuator with auxiliary friction exhibited a top torque of 3.85 N·mm, which was 55 times that of the actuator without auxiliary friction. Moreover, the actuator demonstrated a resolution of 1.2 μrad and a speed of 367.5 mrad/s. Experimental results showed that the auxiliary friction method could assist the actuator in achieving stable and effective stick-slip motion, thereby broadening its practical applications.