4D Printing of Highly Maneuverable Robots: Controllable Power Amplification Behaviours of Stimulus-Response Materials.

Highly maneuverable robots can cross obstacles or move quickly with running, jumping, ejection, or multimodal combinations, exhibiting advantages in aerospace, agriculture, medical treatment, etc. Due to the behaviors of high-energy bursts and the huge vibrations during motions, these robots need to be simple and reliable. 4D printing of highly maneuverable robots addresses this challenge by combining the power amplification of stimulus-response materials and additive manufacturing technologies. It integrates actuation, sensing, and control modules into one component with a highly integrated structure and controllable high-mobility movement. Herein, this paper presents a review of highly maneuverable robots based on 4D printing, focusing on the key technologies from design to fabrication. Firstly, the manufacturing processes of 4D printing for highly maneuverable robots are overviewed. Then, from a biomimetic perspective, structural designs for power amplification are reviewed. After summarizing stimulus-response materials applicable to the 4D-printed highly maneuverable robots, the strategies employed to control the direction, speed, mode, and response time of robotic motion are elaborated. Finally, current challenges and the perspectives on 4D printing of highly maneuverable robots are highlighted.