Soft Autonomous Materials—Using Active Elasticity and Embedded Distributed Computation

Abstract

The impressive agility of living systems seems to stem from modular sensing, actuation and communication capabilities, as well as intelligence embedded in the mechanics in the form of active compliance. As a step towards bridging the gap between man-made machines and their biological counterparts, we developed a class of soft mechanisms that can undergo shape change and locomotion under pneumatic actuation. Sensing, computation, communication and actuation are embedded in the material leading to an amorphous, soft material. Soft mechanisms are harder to control than stiff mechanisms as their kinematics are difficult to model and their degrees of freedom are large. Here we show instances of such mechanisms made from identical cellular elements and demonstrate shape changing, and autonomous, sensor-based locomotion using distributed control. We show that the flexible system is accurately modeled by an equivalent spring-mass model and that shape change of each element is linear with applied pressure. We also derive a distributed feedback control law that lets a belt-shaped robot made of flexible elements locomote and climb up inclinations. These mechanisms and algorithms may provide a basis for creating a new generation of biomimetic soft robots that can negotiate openings and manipulate objects with an unprecedented level of compliance and robustness.

Design, fabrication and control of soft robots

“…3b) is an example of semi-soft continuum robot; while the caterpillar robot 20 ( Fig. 1a) and the rolling belt robot 21 are examples of soft continuum robots. These soft machines have modular bodies consisting of soft rubber segments, which can be composed serially or in parallel to create complex morphologies.…”

“…Valve sequencing means that a valve is turned on for some duration of time to pressurize the actuator and then turned off to either hold or deflate it. Many soft robotic systems use this control approach 21,28,29,34,10 . Marchese et al demonstrated continuously adjustable, variable pressurization using a fluidic drive cylinder 30 .…”

Robust biopolymer based ionic–covalent entanglement hydrogels with reversible mechanical behaviour

“…As soft and wet materials, hydrogels are a substance that is reminiscent of soft biological tissue and have been investigated over the past 30 years as candidate materials for soft tissue engineering scaffolds 1,2,4,5 . However, new applications of hydrogels such as soft robotics [6][7][8] and cartilage tissue scaffolds 9 require hydrogels with enhanced mechanical performance which has stimulated an investigation into how hydrogels may be made tougher and more enduring [10][11][12][13] .…”

Towards a Self-contained Soft Robotic Fish: On-Board Pressure Generation and Embedded Electro-permanent Magnet Valves

“…Miniature CO 2 cartridges in conjunction with a custom pressure regulating system are used as an onboard pressure source and embeddable electro-permanent magnet (EPM) [9] valves [13] are used to address supporting hardware requirements. It is shown that this system can repeatedly generate and regulate supply pressure while driving a fluidic elastomer actuator (FEA) [7,14,13]. To demonstrate our approach in creating tetherless soft mobile robots, this paper focuses on an example case-study: a soft robotic fish.…”

“…We build our robots relying on a novel actuator technology, tagged as fluidic elastomer actuators (FEAs) [7,14,13]. FEAs use synthetic elastomer films as pneumatic or hydraulic bending elements.…”