A Miniature Self-Moving Piezoelectric Actuator With High Carrying/Positioning Capability Inspired by Shape and Gaits of Bird’s Legs

Inspired by the fact that the birds’ bodies are supportable with their thin legs, we develop a miniature self-moving piezoelectric actuator (MSPA) with high carrying/positioning capability. Here, the λ shape’s lower part and the ground form a steady frame. Meanwhile, the MSPA moves in the forward and backward movements by exciting longitudinal and bending vibrations, interestingly imitating the running-up and walking gaits. First, by using a Krimhertz-transmission-theory-based model, the key dimension was adjusted to enhance the driving-force-to-weight ratio. Then, an onboard circuit was designed to not only produce the high-amplitude ac voltage with a 3.7 V battery but also offer the feedback to achieve the straight movement. Finally, a prototype 55 × 45 × 55 mm³ in size and 54.75 g in weight was made and its moving/carrying/positioning performance was assessed. In a tethered manner, the MSPA yielded the maximal payload of 3.47 kg (63.38 times of its weight), the maximal speed of 202 mm/s, and the maximal towing force of 2.3 N. In an untethered manner, the minimal step displacement reached 29.1 nm and the cost of transport (CoT) was 8.45. The high positioning and carrying capabilities make the MSPA potentially applicable to the focusing and scanning systems.