Publications by Yi Sun | EPFL Graph Search

Dual Stiffness Tensegrity Platform for Resilient Robotics

Dario Floreano, Stefano Mintchev, Yi Sun, Davide Zappetti

Collision resilience is an important feature of robots deployed in unstructured and partially unpredictable environments. Herein, a novel dual stiffness (DS) tensegrity platform to integrate collision resilience into a robot body is proposed. The proposed DS tensegrity platform is rigid during normal robot operation, but softens upon collision to withstand the impact. The DS behavior is achieved by means of a novel DS strut that is rigid, but can buckle without breaking under high loads, thus preventing damage to the robot. Compression tests and finite element method simulations show that both the DS struts and DS tensegrities undergo substantial stiffness change with maximum load-bearing ratios up to 10.5 and 5.74, respectively, before and after buckling. These DS tensegrity structures are integrated into two types of robots, a drone and a rover, that are shown to withstand falls from 2 and 5 m, respectively. The mechanical tunability of the proposed DS tensegrity system makes it suitable for impact attenuation in a wide range of situations and robot types.

2022

Electro-Adhesive Tubular Clutch for Variable-Stiffness Robots

Omar Aloui, Krishna Manaswi Digumarti, Dario Floreano, Hoang Vu Phan, Yi Sun

Electro-adhesive clutches have become effective tools for variable stiffness functions in many robotic systems due to their light weight, high speed and strong brake force. In this paper, we present a novel, tubular design of an electro-adhesive clutch. Our clutch consists of flexible electrode sheets rolled into a tubular structure. This design allows encapsulating large electrode areas in a compact size for strong brake force. Additionally, the tubular structure acts as a guide for directional sliding without external guides. The structure also ensures that the electrode surfaces are encapsulated, preventing the accumulation of dust and thus leading to reliable performance. This structure is therefore an improvement over the commonly used planar designs. The characterization of the electro-adhesive tubular clutch shows that the frictional force increases with the increase of the electrode contact area, the decrease of the roll diameter and the dielectric layer thickness. A retractable tubular clutch is made by fixing an elastic cable along the clutch axis and achieves a stiffness change factor up to 260. Applications of this retractable clutch in robotics to achieve variable stiffness are demonstrated in two systems: a tensegrity structure and a wing skeleton. Changes in stiffness by 13.2 and 30.2 times are achieved for the two systems, respectively. The proposed tubular clutch is an effective means of achieving variable stiffness, particularly in the case of robotic systems that transmit forces through tensioned cables.

IEEE2022

Powerful 2D Soft Morphing Actuator Propels Giant Manta Ray Robot

Miao Li, Yi Sun

Soft actuator is the main technology that drives the development of soft robotics as it defines the capabilities of soft machines. One of the key challenges in soft actuator research is to simultaneously produce complex morphing (e.g., surface morphing) and high force. Therefore, a soft robotic pad (SRP) was developed as a new soft actuator that can potentially tackle this challenge. This article demonstrates the highly flexible customization process of the SRP regarding fabrication, morphing design, and force scaling for a challenging application: a giant manta ray robot with the Mobuliform swimming mode. Soft robotic pectoral fins (SRPFs) are customized using the SRP technology for the robot. Detailed characterization results show that the SRPFs can generate almost 100 N force or 25 Nm torque with a dual curving motion to mimic the manta ray fin kinematics. The SRPFs are able to propel the manta ray robot to a decent swimming speed with biomimetic fin motions. As a new member of the soft actuator family, SRPs exhibit strong capabilities through this manta ray robot, and they can potentially become unique tools for many engineers and researchers to tackle challenging applications requiring high force and surface morphing.

WILEY2022

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

Hua Bai, Lionel Blanc, Chih-Peng Chang, Qi Chen, Si Chen, Min Chen, Peiwen Chen, Yin Chen, Wei Chen, Zhen Chen, Zheng Dong, Nicolas Dupont, Yuchen Feng, Yunfei Huang, Ying Jiang, Hong Jiang, Li Jin, Andreas Kern, Yonghyun Kim, Deepak Kumar, Ajay Kumar, Rakesh Kumar, Chi Li, Ke Li, Sheng Li, Wei Li, Rui Li, Jun Li, Bo Liu, Fei Liu, Liang Liu, Chong Liu, Yang Liu, Ke Liu, Wei Liu, Xu Liu, Andreas Mayer, Maurizio Molinari, Darren Moore, Sandra Moreno, Paolo Paganetti, Xin Qi, Ziwei Qu, Jun Ren, Giuseppe Russo, Shweta Sharma, Rajat Singh, Yang Sun, Yi Sun, Françoise Gisou van der Goot Grunberg, Ying Wang, Yu Wang, Xin Wang, Jian Wang, Bo Wang, Peng Wang, Xin Wen, Jian Wu, Tian Xia, Liang Xu, Jian Xu, Feng Xu, Zhen Yan, Yi Yang, Jian Yang, Ying Yang, Li Yu, Yan Zhang, Fan Zhang, Yang Zhang, Jian Zhang, Lin Zhang, Li Zhang, Hong Zhang, Hao Zhang, Qing Zhong

Taylor & Francis Inc2016

Characterization of Silicone Rubber Based Soft Pneumatic Actuators

Jamie Paik, Yun Seong Song, Yi Sun

Conventional pneumatic actuators have been a popular choice due to their decent force/torque output. Nowadays, new generation of pneumatic actuator made out of highly compliant elastomers, which we call soft pneumatic actuators (SPA), are drawing increasing attention due to their ease of fabrication, high customizability and innately softness. However, there is no effective method presented to characterize and understand these actuators, such as to measure the force and torque output, range of motion and the speed of actuation. In this work, we present two types of SPAs: bending and rotary actuators. In addition, we have developed two measurement setups to characterize actuators of different geometries. The measured force/torque outputs of different actuators are presented and analyzed. Step responses to certain pressure input are presented and discussed. A simple model is presented to provide physical insight to the observed behavior of the soft actuators. This work provides the basis for designing customized SPAs with application-specific requirements.

Ieee2013

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2013

Sensor and actuator integrated low-profile robotic Origami

Amir Firouzeh, Jamie Paik, Yi Sun

The robotic origami (Robogami) is a low-profile, sheet-like robot with multi degrees-of-freedom (DoF) that embeds different functional layers. Due to its planar form, it can take advantage of precise 2D fabrication methods usually reserved for micro and nano systems. Not only can these methods reduce fabrication time and expenses, by offering a high precision, they enable us to integrate actuators, sensors and electronic components into a thin sheet. In this research, we study sensors, actuators and fabrication methods for Robogami which can reconfigure into various forms. Our main objective is to develop technologies that can be easily applied to Robogamis consisting of many active folds and DoFs. In this paper, after studying the performance of the proposed sensors and actuators in one fold, we use a design for a crawler robot consisting of four folds to assess the performance of these technologies.

Ieee2013

Soft Robot for Gait Rehabilitation of Spinalized Rodents

Grégoire Courtine, Silvestro Micera, Jamie Paik, Yun Seong Song, Yi Sun, Rubia van den Brand, Joachim von Zitzewitz

Soft actuators made of highly elastic polymers allow novel robotic system designs, yet application-specific soft robotic systems are rarely reported. Taking notice of the characteristics of soft pneumatic actuators (SPAs) such as high customizability and low inherent stiffness, we report in this work the use of soft pneumatic actuators for a biomedical use - the development of a soft robot for rodents, aimed to provide a physical assistance during gait rehabilitation of a spinalized animal. The design requirements to perform this unconventional task are introduced. Customized soft actuators, soft joints and soft couplings for the robot are presented. Live animal experiment was performed to evaluate and show the potential of SPAs for their use in the current and future biomedical applications.

Ieee2013

PyBrain

Tom Schaul, Yi Sun, Daniël Pieter Wierstra

PyBrain is a versatile machine learning library for Python. Its goal is to provide flexible, easy-to-use yet still powerful algorithms for machine learning tasks, including a variety of predefined environments and benchmarks to test and compare algorithms. Implemented algorithms include Long Short-Term Memory (LSTM), policy gradient methods, (multidimensional) recurrent neural networks and deep belief networks.

Massachusetts Institute of Technology Press2010