ConTac: a novel system for shape and contact detection of continuum robots

Ishikawa, Japan -- In nature, many organisms like octopuses with their flexible tentacles or elephants with their trunks, exhibit remarkable dexterity. Inspired by these natural structures, researchers aim to develop highly flexible continuum robots that offer robustness and safety. Ideally, a continuum robot is characterized by many degrees of freedom (DOFs) and the number of joints, more than needed for most tasks. These characteristics allow them to adjust and modify their shape dynamically, enabling them to avoid obstacles and unexpected situations. However, their complex movements make it difficult to characterize their shape and motion.

Traditional analytical techniques to obtain solutions for continuum robots' kinematic and dynamic problems rely on complex modeling, increasing computational cost. Alternatively, flexible sensors built into continuum robots can be used to track their shape and movement, but this method requires many low-resolution sensors, making the system cumbersome. A more promising solution is employing a single sensing module at the end of a continuum robot. However, previous studies in this direction have mostly focused on the robot’s posture and did not address contact detection.

Addressing this gap, a team of researchers from Japan, led by Associate Professor Van Anh Ho from the Japan Advanced Institute of Science and Technology (JAIST), developed a new system called ConTac. This system can estimate the shape and contact of a robotic arm with soft skin. Dr. Ho explains, “The ultimate goal of this system is to be implemented in a continuum robot, but in this study, we focused on perception using an articulated robotic arm and soft skin for verification”. The team included doctoral course students Tuan Tai Nguyen and Quan Khanh Luu from JAIST, as well as Dr. Dinh Quang Nguyen from VNU-UET university in Hanoi. Their study has been presented at the Robotics: Science and Systems (RSS) 2024 conference.

The ConTac system consists of a backbone that mimics the bending of a continuum robot, soft skin with markers, a camera to observe skin deformation, models for shape and contact sensing of the skin, and a contact-aware control regime. This system can be applied to any ConTac unit or any other robot with the same mechanism and form without any calibration. A ConTac unit is an assembled continuum-emulated robot arm with a backbone and soft skin. The researchers also developed an admittance-based controller for this system that uses perceptual information to guide the robotic arm’s movements. Additionally, the ConTac unit is cost-effective and can be fabricated from conventional materials

This innovative system employs two deep-learning models for shape reconstruction and contact detection of the soft-continuum skin. These models were trained entirely using simulation images and were then directly adapted to real robots without fine-tuning, saving time and resources. The system’s transferability was tested on two different ConTac units, which performed similarly without any additional adjustments.

Highlighting the significance of this study, Dr. Ho remarks, “The ConTac system is aimed to be used in a variety of robotic systems without the need for complex adjustments. Flexible robotic arms equipped with our system are ideal for smart agriculture and healthcare services where robots must navigate environments with many obstacles and interact safely with humans. Their softness and flexibility combined with the ability to sense the surroundings make them perfect for interacting with plants and patients.”

The sensing and control principles used in this framework could lead to new tactile sensors that can be attached to any existing robotics system, offering new sensing and control paradigms for safe human-robot interaction without altering the robot’s original design. Looking ahead, Dr. Ho concludes, “Imagine a society where every robot and machine possesses a sense of touch. This transformation would revolutionize industries and daily life.”

 

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Reference

Title of original paper:	ConTac: Continuum-Emulated Soft Skinned Arm with Vision-based Shape Sensing and Contact-aware Manipulation
Authors:	Tuan Tai Nguyen, Quan Khanh Luu, Dinh Quang Nguyen, and Van Anh Ho*
Comference:	Robotics: Science and Systems (RSS) 2024
DOI:	NA

 

                                           

About Japan Advanced Institute of Science and Technology, Japan

Founded in 1990 in Ishikawa prefecture, the Japan Advanced Institute of Science and Technology (JAIST) was the first independent national graduate school in Japan. Now, after 30 years of steady progress, JAIST has become one of Japan’s top-ranking universities. JAIST counts with multiple satellite campuses and strives to foster capable leaders with a state-of-the-art education system where diversity is key; about 40% of its alumni are international students. The university has a unique style of graduate education based on a carefully designed coursework-oriented curriculum to ensure that its students have a solid foundation on which to carry out cutting-edge research. JAIST also works closely both with local and overseas communities by promoting industry–academia collaborative research.  

 

About Associate Professor Van Anh Ho from Japan Advanced Institute of Science and Technology, Japan

Van Anh Ho is currently an Associate Professor at the Nanomaterials and Devices Research Area, Japan Advanced Institute of Science and Technology (JAIST), Japan. He obtained his M.S. and Ph.D. degrees from Ritsumeikan University in 2009 and 2012, respectively. At JAIST, he also leads the Ho laboratory. He has over 80 publications with over 1000 citations. He is a member of The Robotics Society of Japan. His research interests include tangible devices, manipulation, tactile sensing, and soft robotics.

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