Nov 10 2020
Taking a cue from nature, UNSW Sydney engineers have developed a novel soft fabric robotic gripper that acts similar to an elephant’s trunk to grip, pick up, and release objects without damaging them.
A new soft fabric robotic gripper in action, developed by a team of UNSW Sydney Engineering researchers, led by Dr. Thanh Nho Do. Image Credit: UNSW Engineering.
According to the researchers, the multipurpose technology could be extensively used in industries, which involve the handling of delicate objects, like food, agriculture, and the resource and scientific exploration sectors; the new technology could even be used as personal assistive devices or for human rescue operations.
Dr Thanh Nho Do, Scientia Lecturer and director of UNSW Medical Robotics Lab, stated that if his group successfully finds an industry partner, the robotic gripper would be available in the market in the next 12 to 16 months.
Dr Do is the senior author of a study that features the latest invention, recently reported in the Advanced Materials Technologies journal. He worked with a PhD candidate and the study’s lead author Trung Thien Hoang, Phuoc Thien Phan, Mai Thanh Thai, and his colleague Nigel Lovell—a Scientia Professor and Head of the Graduate School of Biomedical Engineering.
Our new soft fabric gripper is thin, flat, lightweight and can grip and retrieve various objects—even from confined hollow spaces—for example, a pen inside a tube. This device also has an enhanced real-time force sensor which is 15 times more sensitive than conventional designs and detects the grip strength required to prevent damage to objects it’s handling.
Dr Thanh Nho Do, Scientia Lecturer and Director, UNSW Medical Robotics Lab
Dr Do continued, “There is also a thermally-activated mechanism that can change the gripper body from flexible to stiff and vice versa, enabling it to grasp and hold objects of various shapes and weights—up to 220 times heavier than the gripper’s mass.”
Nature-Inspired Robotics
Dr Do added that the investigators took a cue from nature when developing their soft fabric gripper.
“Animals such as an elephant, python or octopus use the soft, continuum structures of their bodies to coil their grip around objects while increasing contact and stability – it’s easy for them to explore, grasp and manipulate objects,” Dr Do further added.
These animals can do this because of a combination of highly sensitive organs, sense of touch and the strength of thousands of muscles without rigid bone—for example, an elephant’s trunk has up to 40,000 muscles. So, we wanted to mimic these gripping capabilities—holding and manipulating objects are essential motor skills for many robots.
Dr Thanh Nho Do, Scientia Lecturer and Director, UNSW Medical Robotics Lab
Improvement on Existing Grippers
The new soft gripper developed by the team was an improvement on prevailing designs, which had drawbacks that restricted their usage, informed Dr Do.
“Many soft grippers are based on claws or human hand-like structures with multiple inward-bending fingers, but this makes them unsuitable to grip objects that are oddly shaped, heavy or bulky, or objects smaller or larger than the gripper’s opening,” he added.
Many existing soft grippers also lack sensory feedback and adjustable stiffness capabilities, which means you can’t use them with fragile objects or in confined environments. Our technology can grip long, slender objects and retrieve them from confined, narrow spaces, as well as hook through holes in objects to pick them up—for example, a mug handle.
Dr Thanh Nho Do, Scientia Lecturer and Director, UNSW Medical Robotics Lab
Trung Thien Hoang, the study’s lead author, stated that the fabrication technique developed by the researchers was also easy and scalable, which enabled the team to easily create the robotic gripper at different volumes and sizes—for instance, a 1-m long gripper could handle objects that have a minimum diameter of 300 mm.
At the time of testing, a gripper prototype weighing 8.2 g can lift an object weighing 1.8 kg—which is over 220 times the mass of the gripper—while a prototype measuring 13 cm in length could circle an object that measures 30 mm in diameter.
Professor Lovell stated, “We used a manufacturing process involving computerised apparel engineering and applied newly designed, highly sensitive liquid metal-based tactile sensors for detecting the grip force required.”
He added, “The gripper’s flat continuum also gives it superior contact with surfaces as it wraps around an object, while increasing the holding force. What’s more, the total heating and cooling cycle for the gripper to change structure from flexible to rigid takes less than half a minute, which is among the fastest reported so far.”
Integrating Robotic Arms and the Sense of Touch
After successfully testing and validating the new robotic gripper as a complete device, Dr Do has currently filed a provisional patent for the technology.
He believes that the robotic gripper would be available in the market in the next 12 to 16 months, provided he finds an industry partner.
“We now aim to optimise the integrated materials, develop a closed-loop control algorithm, and integrate the gripper into the ends of robotic arms for gripping and manipulating objects autonomously,” added Dr Do.
“If we can achieve these next steps, there will be no need to manually lift the gripper which will help for handling very large, heavy objects. We are also working on combining the gripper with our recently announced wearable haptic glove device, which would enable the user to remotely control the gripper while experiencing what an object feels like at the same time,” Dr Do concluded.
Journal Reference:
Hoang, T, T., et al. (2020) Bio-Inspired Conformable and Helical Soft Fabric Gripper with Variable Stiffness and Touch Sensing. Advanced Materials Technologies. doi.org/10.1002/admt.202000724.
New robotic ‘snake’ device grips, picks up objects
Video Credit: UNSW Sydney.