Inspired by nature, scientists develop new soft gripper for robots

Soft robotic grippers can greatly improve productivity in many fields, however, existing designs are too complex and expensive. A foreign research team has developed ROSE, a novel embracing soft gripper inspired by the opening and closing of roses. ROSE has a surprisingly simple, cheap and scalable design that can pick up a variety of objects without damaging them even in challenging environments and conditions.

While grasping objects is a relatively simple task for us humans, there are a lot of mechanisms involved in this simple task. Picking up an object requires fine control of the fingers, their positions, and the pressure applied by each finger, which in turn requires sophisticated sensing capabilities. It is no surprise that robotic grasping and manipulation is an important area of ​​research in the field of robotics.

Today, robotic hands have replaced humans in a variety of complex and dangerous activities, including restaurants, farms, factories and manufacturing plants. Generally speaking, soft robotic grippers are better suited for tasks such as picking up fragile objects, such as fruits and vegetables. However, while soft robots are promising as harvesting tools, they often share a common disadvantage: they are expensive. Most soft robotic gripper designs require complex assembly of multiple parts, which increases development and maintenance costs.

A research team at the Japan Advanced Institute of Technology (JAIST), led by Associate Professor Van Anh Ho, has come up with a groundbreaking solution to these problems, drawing inspiration from nature to develop an innovative soft robotic gripper called "ROSE," which stands for "Rotation-based Extrusion Gripper."

What is impressive about ROSE is its design, where the soft gripping part has the shape of a cylindrical funnel or sleeve and is connected to a hard circular base, which in turn is connected to the actuator's shaft. The funnel must be placed over the object to be picked up, covering a significant portion of its surface area, and then the actuator turns the base so that the outer skin of the flexible funnel wraps tightly around the object. This mechanism is roughly inspired by the changing shape of a rose, which opens during the day and closes at night.

ROSE has significant advantages over more traditional grippers. Firstly, it is much cheaper to manufacture, with the hard parts all being 3D printed and the funnel itself being easily produced using moulds and liquid silicone rubber, which ensures the design is easily scalable and suitable for mass production.

Secondly, ROSE can easily pick up a variety of objects without complex control and sensing mechanisms. Unlike grippers that rely on finger-like structures, ROSE's sleeve applies gentler and more uniform pressure, which makes ROSE more suitable for handling fragile agricultural products such as strawberries and pears, as well as slippery objects. The gripper weighs less than 200 grams, with an impressive payload-to-weight ratio of 6812%.

Third, ROSE is extremely durable and strong. The team showed that it could successfully continue to pick up objects even after 400,000 trials. Moreover, the funnel continued to function properly in the presence of significant cracks or cuts. “The proposed gripper performed exceptionally well in demanding situations, and it was able to withstand rigorous testing, where we cut the funnel at its full height into four separate parts, proving its capabilities,” said Assoc. “This testing highlighted the robot’s exceptional resilience and optimal performance under challenging conditions,” said Prof. Ho.

Finally, ROSE can be given sensing capabilities. The researchers achieved this by placing multiple cameras on top of a circular base, pointed at the inside of the funnel, which is covered with markers. The cameras can pick up the positions of the markers and analyze them through image processing algorithms. This promising approach can estimate the size and shape of the grasped object.

The research team noted that ROSE is a competitive choice for a variety of applications, including harvesting operations and sorting items in factories. "The ROSE gripper has great potential to revolutionize grasping applications and gain wide acceptance in various fields," concluded Assoc. "Its simple yet robust and reliable design will inspire researchers and manufacturers to use it for a variety of grasping tasks in the near future," said Professor Ho.