Design for Actuation

Some Inverse and Generative Design Problems in Soft Robotics

With soft robots finding utility in different application domains such as healthcare and agriculture, their requirements are getting more stringent. Designers need to reconcile through contrasting attributes such as deformation modes, stiffness, forces, aesthetics, ease of controls etc. and map them to physical design features within the capabilities of modern manufacturing. In this workshop talk, I present the design space of fiber reinforced pneumatic actuations and explore two types of problems, a topology design problem, and an inverse design problem. I will present an example of a compact soft continuum manipulator with large dexterity and workspace designed through careful exploration of the workspace. Lastly, I will outline how the future of soft robotics design is strongly coupled to controls, leading to a codesign space that optimizes both design parameters and control effort.

Towards Improved Performance and Portability of Soft Pneumatic Robots via Design Optimization of Pneumatic Systems

Soft pneumatic actuators (SPAs) are highly desirable for interactive robotics applications owing to their unconventional properties like high compliance, safe human-machine interaction and adaptable design space. While the SPA force and displacement are a function of their design, materials, and actuation pressure, the dynamic behaviour is governed by the airflow generated and controlled by the pneumatic supply systems (PSSs). The functionality of the PSS and its components such as source, reservoir, valve, tubing and fittings, is known qualitatively. However, the inter-dependence of the PSS components and their impact on the SPA dynamic behaviour has not been quantified, especially in the context of performance and portability. In this talk, I will present a modelling approach, simulation results, and experimental validation, investigating the dynamic response of SPAs. I will demonstrate how the presented approach can be used to optimize the selection and control of PSS components to simultaneously meet requirements of performance, portability, and other user-based requirements such as mass and size. Finally, I will showcase some specific examples on (i) optimizing a wearable PSS for maximum duration of operation, and (ii) optimizing tubing diameter for maximum actuation frequency., and minimal air and energy consumption.

Beethoven in the Air: Designing Soft Robots with Complex Actuation Sequences and a Single Supply

Soft robots typically require a separately controlled pressure for every actuated degree of freedom. For complex soft robots, this leads to a large volume of hard, lag-inducing and energy-consuming components. Here, we propose an underactuated system architecture with the same functionality but only a single controlled pressure. In this architecture, every actuator is an individually designed structure that buckles on inflation. The unique buckling thresholds of each actuator convert the common pressure signal into distinct series of snapthrough actions. We describe a procedure to translate a given actuation sequence first into an ordered set of buckling thresholds and then into actuator designs that can be assembled to perform the given sequence. We apply this procedure to the design of a soft robotic system that performs Beethoven’s “Ode to Joy” on a piano keyboard from a single air supply line. This research enables the emergence of smaller, cheaper and more compliant robots with functionality embodied in their mechanical design rather than imposed by programming.

Soft Grasping by Exploiting Buckling of Kirigami Shells

The ability to grab and hold objects is a vital and fundamental operation in biological and engineering systems. In this talk, I will present a soft gripper design using a simple material system that enables precise and rapid grasping and can be miniaturized, modularized, and remotely actuated. The kinematics and robustness of this soft gripper are achieved by designing the deformation of kirigami patterned thin shells using a combination of experiments, finite element simulations, and theoretical modeling. I will also demonstrate the advanced functionalities of the kirigami shell gripper by integrating with an existing robotic platform to simultaneously grasp multiple delicate objects, and actuating remotely using a magnetic field. These soft and lightweight grippers may have applications in robotics, haptics, and biomedical device design.