Climbing robots using adhesion force - Spider robot

 4. Spider robot

   Spiders also use dry adhesive, which rely primarily on Van der Waals forces. Climbing robots are researching using dry adhesive. There are climbing robots using dry adhesion force: 1) wheeled locomotion system and 2) inspired by the locomotion of geckos. I will introduce a climbing robot, Abigaille II, inspired by the locomotion of spider.

   The feet of Abigaille II consist of a two-layer adhesive, which was manufactured in two steps. First, a 1×3㎠ layer with microposts was manufactured by casting Polydimethylsiloxane (PDMS) in a microstructured mold. There are scanning electron microscope (SEM) images of microposts placed in adhesive used by spider robot in following figure (Fig. 1). The second layer is consisted of 1×1㎠ macroposts array. Each post has about 1㎟ cross-section area with approximately 3 mm tall.

Fig. 1 SEM images of the microposts in the adhesive used in the climbing robot: (a) magnification at 2500X and (b) magnification at 5000X

   
   Abigaille-II has 36 DOF of which 18 are actively controlled. In order to reduce the robot’s mass, its mechanical structure consists of mosaic composition of Printed Circuit Boards(PCB) (Fig. 2). 

Fig. 2 (a) Leg’s geometry and (b) CAD model of the robot.

  It has sensors in each foot to analyze forces during climbing. Fig. 3 shows the force characterization and scheme of different phases in one step cycle. (Fig. 3) It moves as single leg moves while other legs fix their position on wall and repeating this movement to all legs. It can move 4.5cm/s on ground, 0.1cm/s on vertical wall.

Fig. 3 Force characterization on legs 1, 6, and 5 during climbing: (a)–(c) force graph of legs 1, 6, and 5; and (d) Scheme of different phases in one step cycle.

Fig. 4 Snap shots of robot transitioning from ground to wall.