In recent years, there has been significant progress in the fabrication of exploration and inspection robots and actuators designed for confined spaces that are inaccessible to humans [1][2]. However, the fabrication process of existing robots and actuators designed for narrow environments is complex. Film actuators offer an effective strategy to address this problem. The structure of film actuators is relatively simple, and they are characterized by a lightweight and thin profile. The use of film actuators in exploration and inspection robots allows for the transportation of a large number of robots simultaneously. Accordingly, we proposed a new robotics concept using film actuators and structures called “Filmotics” [3].
Textured actuator using polyimide film was fabricated in our laboratory. Polyimide film exhibits high environmental resistance and mechanical properties. The actuator is fabricated by simultaneously welding two types of polyimide film and transferring a pattern on the surface. An aluminum foil is deposited on one side of the actuator, and a pattern for electric heating is formed by laser processing. The actuator is heated by applying electrical power to the electrodes and unfolds. The actuator returns to its initial curved state by natural cooling.
In this research, ultra-thin endoscope was fabricated to detect the inside of a narrow environment. The film endoscope is shown in Fig. 1. A small camera is mounted on top of the textured actuator. The endoscope can move through the field of view with one DOF by applying electrical power to the textured actuator. The curvature radius and the generated force of the textured actuator were evaluated when the electric power was applied. Additionally, the camera took pictures of the surrounding conditions while the actuator drove. The dimensions of the fabricated film endoscope are 28 mm × 45 mm, with a maximum protrusion of 4.1 mm and a mass of 85.4 mg. The actuator is constructed from film, it is imperative that the camera does not impede the operation of the actuator drive. The camera was selected based on its diminutive dimensions, minimal weight, and limited number of electrodes for wiring. The dimensions of the camera are 1.1 mm × 1.1 mm × 2.2 mm, and its mass is 4.6 mg. The camera is damaged by high temperatures. Thus, the temperature of the textured actuator surface was monitored for a five-minute interval. The results showed that the elevated temperature generated during actuator operation was not transferred to the camera mounted on the actuator tip. The radius of curvature of the endoscope was 19 mm by applying an electrical power of 1.5 W and a temperature of 216 ℃. The generated force was 20 mN under the same conditions. It is therefore expected to be useful in confined environments.
The endoscope is thin and suitable for confined environments. The direction of bending can be changed by changing the texture pattern. In the future, a multi-degree-of-freedom endoscope will be developed by adding multiple textures.
- Suzumori, K.; Kondo, F.; Tanaka, H. Miniature Walking Robots. The Robotics Society of Japan. 1993, 385-390.
- Braccini,M ; Gardinazzi,Y ; Roli,A ; Villani,M. Sensory–Motor Loop Adaptation in Boolean Network Robots. Robust Motion Recognition Based on Sensor Technology. 2024, 24, 3393.
- Yamaguchi, D.; Hanaki, T.; Ishino, Y.; Hara, M.; Takasaki, M.; Mizuno, T. Concept and Prototype of Soft Actuator for Liquid Nitrogen Temperature Environments. Journal of Robotics and Mechatronics. 2020, 32, 1019-1026.
