Meet the Paik Lab

Welcome to the second of our Lab videos section where we introduce the NCCR Robotics lab, PI, NCCR Robotics members and their work. On this occasion we present Paik Lab.

Stéphanie Lacour appointed Full Professor

12.12.16 – Congratulations to Prof. Stéphanie Lacour who has been appointed Full Professor of Microtechnology and Bioengineering in the School of Engineering (STI), EPFL.Prof. Lacour has recently made news with her work in NCCR Robotics with both the e-dura implant and the stretchable solid-liquid electrical film. Read more.

A Composite Thread that Varies in Rigidity

27.10.16 – Soft “hardware” components are becoming more and more popular solutions within the field of robotics. In fact, softness, compliance and foldability bring significant advantages to devices, by allowing conformability and safe interactions with users, objects and unstructured environments. However, for some applications the softness of components adversely reduces the range of forces that …

Past Events

Date/Time Event Description
28 Mar 2017
2:30 pm – 4:30 pm
Talks: By Professor Fumiya Iida & By Professor Robert J. Full
EPFL, Lausanne Suisse
Talks: Model-free design optimization of soft robots: Any hope? By Professor Fumiya Iida (Cambridge Univ.), (14:30 – 15:30). BioMotion Science: Leapin’ Lizards, Compressed Cockroaches and Smart Squirrels Inspire Robots By...
30 Sep – 7 Jan 2016
All Day
The origami robot Tribot from Paik lab is currently at the exhibition in +Ultra Knowledge & Gestaltung in Berlin

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A Foldable Antagonistic Actuator

  • Authors: Shintake, Jun; Rosset, Samuel; Schubert, Bryan Edward; Floreano, Dario; Shea, Herbert

We report on an actuator based on dielectric elastomers that is capable of antagonistic actuation and passive folding. This actuator enables foldability in robots with simple structures. Unlike other antagonistic dielectric elastomer devices, our concept uses elastic hinges to allow the folding of the structure, which also provides an additional design parameter. To validate the actuator concept through a specific application test, a foldable elevon actuator with outline size of 70 mm × 130 mm is developed with angular displacement range and torque specifications matched to a 400-mm wingspan micro-air vehicle (MAV) of mass 130 g. A closed-form analytical model of the actuator is constructed, which was used to guide the actuator design. The actuator consists of 125-μm-thick silicone membranes as the dielectric elastomers, 0.2mm-thick fiberglass plate as the frame structure, and 50-μm-thick polyimide as the elastic hinge. We measured voltage-controllable angular displacement up to ±26° and torque of 2720 mN · mm at 5 kV, with good agreement between the model and the measured data. Two elevon actuators are integrated into the MAV, which was successfully flown, with the foldable actuators providing stable and well-controlled flight. The controllability was quantitatively evaluated by calculating the correlation between the control signal and the MAV motion, with a correlation in roll axis of over 0.7 measured during the flights, illustrating the high performance of this foldable actuator.

Posted on: September 16, 2014

A Perching Mechanism for Flying Robots Using a Fibre-Based Adhesive

  • Authors: Daler, Ludovic; Klaptocz, Adam; Briod, Adrien; Sitti, Metin; Floreano, Dario

Robots capable of hover flight in constrained indoor environments have many applications, however their range is constrained by the high energetic cost of airborne locomotion. Perching allows flying robots to scan their environment without the need to remain aloft. This paper presents the design of a mechanism that allows indoor flying robots to attach to vertical surfaces. To date, solutions that enable flying robot with perching capabilities either require high precision control of the dynamics of the robot or a mechanism robust to high energy impacts. We propose in this article a perching mechanism comprising a compliant deployable pad and a passive self-alignment system, that does not require any active control during the attachment procedure. More specifically, a perching mechanism using fibre-based dry adhesives was implemented on a 300 g flying platform. An adhesive pad was first modeled and optimized in shape for maximum attachment force at the low pre-load forces inherent to hovering platforms. It was then mounted on a deployable mechanism that stays within the structure of the robot during flight and can be deployed when a perching maneuver is initiated. Finally, the perching mechanism is integrated onto a real flying robot and successful perching maneuvers are demonstrated as a proof of concept.

Posted on: January 29, 2013

A soft robotic actuator using dielectric minimum energy structures

  • Authors: Shintake, Jun; Rosset, Samuel; Floreano, Dario; Shea, Herbert

Dielectric minimum energy structures are capable of large actuation stroke, and consist of a pre-stretched dielectric elastomer actuator (DEA) laminated onto a flexible frame, which makes it easy to obtain both simple and complex shapes. We report here on the fabrication and characterization of a prototype capable of one-dimensional bending actuation. For the DEA, several combinations of ion-implanted PDMS membranes and uniaxial pre-stretch ratio were used. The actuator was characterized by measuring the deformation and output force vs. applied voltage. The results showed that the prototype is able to exhibit bending actuation in the range of around 60 deg. Additionally the initial deformation depends on fabrication parameters such as thickness of the materials, pre-stretch ratio as well as dose of implanted ions.

Posted on: May 14, 2012

Adaptive Morphology: A Design Principle for Multimodal and Multifunctional Robots

  • Authors: Mintchev, Stefano; Floreano, Dario

Morphology plays an important role in behavioral and locomotion strategies of living and artificial systems. There is biological evidence that adaptive morphological changes can not only extend dynamic performances by reducing tradeoffs during locomotion but also provide new functionalities. In this article, we show that adaptive morphology is an emerging design principle in robotics that benefits from a new generation of soft, variable-stiffness, and functional materials and structures. When moving within a given environment or when transitioning between different substrates, adaptive morphology allows accommodation of opposing dynamic requirements (e.g., maneuverability, stability, efficiency, and speed). Adaptive morphology is also a viable solution to endow robots with additional functionalities, such as transportability, protection, and variable gearing. We identify important research and technological questions, such as variable-stiffness structures, in silico design tools, and adaptive control systems to fully leverage adaptive morphology in robotic systems.

Posted on: September 27, 2016

An Active Connection Mechanism for Soft Modular Robots

  • Authors: Germann, Jürg Markus; Dommer, Michael; Pericet Camara, Ramon; Floreano, Dario

To date, most modular robotic systems lack flexibility when increasing the number of modules due to their hard building blocks and rigid connection mechanisms. In order to improve adaptation to environmental changes, softness on the module level might be beneficial. However, coping with softness requires fundamental rethinking the way modules are built. A major challenge is to develop a connection mechanism that does not limit the softness of the modules, does not require precise alignment and allows for easy detachment. In this paper, we propose a soft active connection mechanism based on electroadhesion. The mechanism uses electrostatic forces to connect modules. The method is easy to implement and can be integrated in a wide range of soft module types. Based on our experimental results, we conclude that the mechanism is suitable as a connection principle for light-weight modules when efficiency in a wide range of softness, tolerance to alignment and easy detachment are desired. The main contributions of this article are (i) the qualitative comparison of different connector principles for soft modular robots, (ii) the integration of electroadhesion, featuring a novel electrode pattern design, into soft modules, and (iii) the demonstration and characterization of the performance of functional soft module mockups including the connection mechanism.

Posted on: September 6, 2011

Artificial muscles for soft robots

  • Authors: Shintake, Jun; Rosset, Samuel; Floreano, Dario; Shea, Herbert

Recent work on soft gripper using an artificial muscle technology was shown at Festival de robotique in EPFL.

Posted on: April 24, 2013

Biomimetic Underwater Robots Based on Dielectric Elastomer Actuators

  • Authors: Shintake, Jun; Shea, Herbert; Floreano, Dario

Dielectric elastomer actuators (DEAs), a soft actuator technology, hold great promise for biomimetic underwater robots. The high-voltages required to drive DEAs can however make them challenging to use in water. This paper demonstrates a method to create DEA-based biomimetic swimming robots that operate reliably even in conductive liquids. We ensure the insulation of the high-voltage DEA electrodes without degrading actuation performance by laminating silicone layers. A fish and a jellyfish were fabricated and tested in water. The fish robot has a length of 120 mm and a mass of 3.8 g. The jellyfish robot has a 61 mm diameter for a mass of 2.6 g. The measured swimming speeds for a periodic 3 kV drive voltage were 8 mm/s for the fish robot, and 1.5 mm/s for the jellyfish robot.

Posted on: October 27, 2016

Contactless deflection sensing of concave and convex shapes assisted by soft mirrors

  • Authors: Dobrzynski, Michal; Halasz, Ionut; Pericet Camara, Ramon; Floreano, Dario

Typical deflection sensors like strain gauges or devices based on optical fibers require physical contact with the deflected substrate during the measurement process. Such contact, however, impacts on the softness of the substrate and may falsify the measurements. In order to overcome this drawback, a novel method of contactless deflection sensing was proposed in a recent work. It was verified that the deflection angle between two planes can be extracted using only a photosensor and a light source bearing a bell-shape angular emission profile. Yet, the range of operation was limited to concave shapes. In this paper, we introduce an alternative configuration of this light-based deflection sensing method to extend its functionality to convex surfaces. Here, a spheroidal mirror bearing a customized profile is introduced above the light source. This mirror redirects part of the emitted light towards the photosensor hindered by the bending surface during convex deflections.We make use of a ray tracing simulation method to design the mirror profiles, which are accurately reproduced in the manufactured prototypes by tuning the fabrication variables of the manufacturing process. Using a shape-sensing prototype, it is verified that the use of the mirror extends the range of detectable deflections by 55deg. to convex bendings, yielding a deviation of only 8.3% from simulated results. Our deflection sensing solution is a promising method to be used as a shape sensor in numerous applications, such as soft robotics platforms or prosthetic devices.

Posted on: March 13, 2012

Contactless deflection sensor for soft robots

  • Authors: Dobrzynski, Michal; Pericet Camara, Ramon; Floreano, Dario

In the emerging field of soft robotics, there is an interest in developing new kinds of sensors whose characteristics do not affect the intrinsic compliance of soft robot components. Additionally, non-invasive shape and deflection sensors may provoke improved solutions to assist in the control of mechanical parts in these robots. Herein, we introduce a novel method for deflection sensing where an LED element and a photodiode are placed on to two substrates connected physically or virtually at a deflection point. The deflection angle between the two planes can be extracted from the LED light intensity detected at the photodiode due to the bell-shaped angular intensity profile of the emitted light. The main advantage of this system is that the components are not in physical contact with the deflection region as in the case of strain gauges and similar sensing methods. The sensor is characterized in a range of deflections of 105-180 degrees, showing a near 1 degree resolution. The experimental data are compared to simulations, modeled by ray tracing. The light intensity vs. deflection angle measurements in our setup display a maximum difference of 9% and an average difference of approximately 5% with respect to the model. Finally, a shape monitoring system has been developed using the proposed concept for a flexible PCB. The system is composed of 12 deflection sensors that operate at frame rate of 33 Hz. This device could be applied to monitor the body shape of a soft robot.

Posted on: July 15, 2011

Dielectric Elastomer Actuators for soft-grasping

  • Authors: Shintake, Jun; Rosset, Samuel; Schubert, Bryan Edward; Floreano, Dario; Shea, Herbert

We demonstrate here a configuration of soft actuator which has several features such as, being completely soft, simple, thin, foldable, and stretchable while having uni/bidirectional bending actuation. Theoretically the actuation can be extended to multidirectional. We used Dielectric Elastomer Actuators (DEA) as a base actuation mechanism, and molded PDMS was used as a substrate of the device.

Posted on: September 5, 2014