Design

The Fabric-Reinforced Controlled Motion Robot (FRCMR) is a soft robot that mimics the basic locomotive methods of both an earthworm and an inchworm.  It is comprised of three silicone bladders arranged in a triangle. Each bladder is divided into two sections allowing the front and back of the robot to operate independently. The bladders are confined within a fabric sleeve.  This sleeve not only limits radial expansion of the bladders but also acts as soft armor, protecting the robot from environmental hazards that could cut or puncture the bladders.  The sleeve is secured to the bladders using tie wraps on either end.

Side view of inflated robot.

Top and front view of uninflated FRCMR.

The robot has feet located at either end of the sleeve. Each foot is a fabric patch that features multiple rows of bristles. Each bristle has bare fabric on the forward facing side and a rubber coating on the rear facing side. Using directional friction, the robot exhibits forward locomotion through linear expansion and contraction. The foot patches can be removed or replaced as required.

Through different inflation patterns, several modes of locomotion can be achieved.

Crawling Motion

Crawling Motion

The simplest mode of locomotion occurs when all three bladders extend and retract simultaneously. This produces a highly stable flat earthworm like crawling motion.

Inchworm Motion

Inchworm Motion

While performing the inchworm motion the robot bends in an upside down U and then straightens.   This is more air-efficient because the bladders only partially deflate. It is also the least stable mode of transport.   

Turning Motion

Turning Motion

The turning motion occurs when the bladders on one side of the sleeve inflate, allowing the robot to pitch in the opposite direction.

Climbing Motion

Climbing Motion

During the climbing motion, the front of the robot bends upwards, extends and then bends back down on top of the obstacle .  

Controls

The robot is controlled via a fluidic control board detailed on the Soft Robotics Toolkit using a closed feedback loop that reads the pressure of each bladder.