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Chapter 21 — Actuators for Soft Robotics

Alin Albu-Schäffer and Antonio Bicchi

Although we do not know as yet how robots of the future will look like exactly, most of us are sure that they will not resemble the heavy, bulky, rigid machines dangerously moving around in old fashioned industrial automation. There is a growing consensus, in the research community as well as in expectations from the public, that robots of the next generation will be physically compliant and adaptable machines, closely interacting with humans and moving safely, smoothly and efficiently - in other terms, robots will be soft.

This chapter discusses the design, modeling and control of actuators for the new generation of soft robots, which can replace conventional actuators in applications where rigidity is not the first and foremost concern in performance. The chapter focuses on the technology, modeling, and control of lumped parameters of soft robotics, that is, systems of discrete, interconnected, and compliant elements. Distributed parameters, snakelike and continuum soft robotics, are presented in Chap. 20, while Chap. 23 discusses in detail the biomimetic motivations that are often behind soft robotics.

AMASC - changing stiffness

Author  Jonathan Hurst et al.

Video ID : 468

AMASC variable stiffness actuator: changing stiffness phase.

VSA-Cube: Arm with high and low stiffness preset

Author  Centro di Ricerca "E. Piaggio"

Video ID : 470

A modular 2-DOF arm, built with VSA-cube actuation units, performing high- and low-stiffness behaviors.

CompAct™ robotics technology

Author  Istituto Italiano di Tecnologia (IIT)

Video ID : 471

Brief video showing CompAct™ actuation units and arm, demonstrating the effects of its core variable damping (VPDA) technology. Key features of these units include: 1. intrinsic safety (lightweight and elastic transmission) meant for safe human-robot collaboration; 2. precision, thanks to the variable damping transmission, protected by international patents; 3. ease of use (no need for experts to program it, easy to reprogram, flexible to use).

VSA-Cube arm: Drawing on a wavy surface (high stiffness)

Author  Centro di Ricerca "E. Piaggio"

Video ID : 472

A 3-DOF arm, built with VSA-cube units, performing a circle on a wavy surface with preset uniformly high stiffness.

VSA-Cube arm: Drawing on a wavy surface (low stiffness)

Author  centro di Ricerca "E. Piaggio"

Video ID : 473

A 3-DOF arm, built with VSA-cube units, performing a circle on a wavy surface with preset low stiffness.

VSA-Cube arm: Drawing on a wavy surface (selective stiffness)

Author  Centro di Ricerca "E. Piaggio"

Video ID : 474

A 3-DOF arm, built with VSA-cube units, performing a circle on a wavy surface with a proper (selective) stiffness preset.

Intrinsically elastic robots: The key to human like performance (Best Video Award)

Author  Sami Haddadin, Felix Huber, Kai Krieger, Roman Weitschat, Alin Albu-Schäffer, Sebastian Wolf, Werner Friedl, Markus Grebenstein, Florian Petit, Jens Reinecke, Roberto Lampariello

Video ID : 475

The advantages of intrinsically elastic robots on their performance are shown by the examples of the DLR LWR III and the DLR Hand Arm System.

DLR Hand Arm System: Punching holes

Author  Alin Albu-Schäffer, Thomas Bahls, Maxime Chalon, Markus Grebenstein, Oliver Eiberger, Werner Friedl, Hannes Höppner, Dominic Lakatos, Daniel Leidner, Florian Petit, Jens Reinecke, Sebastian Wolf, Tilo Wüsthoff

Video ID : 546

The DLR Hand Arm System uses a tool to punch holes into a business card. The passive flexibility in the variable stiffness actuators (VSA) helps to keep a stable grasp during the impact and protects the hardware from damage. The movement is realized by cyclic motion control and a learning algorithm to improve the accuracy of the holes.

DLR Hand Arm System throwing a ball and Justin catching it

Author  Alin Albu-Schäffer, Thomas Bahls, Berthold Bäuml, Maxime Chalon, Markus Grebenstein, Oliver Eiberger, Werner Friedl, Hannes Höppner, Dominic Lakatos, Nico Mansfeld, Florian Petit, Jens Reinecke, Roman Weitschat, Sebastian Wolf, Tilo Wüsthoff

Video ID : 547

The DLR Hand Arm System throws a ball and Justin catches it. There is no data connection between the two systems. Justin catches the ball by visual observation.

Active damping control on the DLR Hand Arm System

Author  Florian Petit, Alin Albu-Schäffer

Video ID : 548

The effectivness of active damping control is shown in a writing task performed by the DLR Hand Arm System.