Conventional robotic grippers face challenges when it comes to handling crops with their diverse shapes and sizes. This has led to a need for more flexible robotic grippers tailored for agricultural applications. In a recent study, researchers unveiled a novel soft robotic gripper called ROtation-based Squeezing grippEr (ROSE) and enhanced its unique wrinkling-based gripping technique through simulations. ROSE’s gentle yet effective grasping ability positions it as a crucial tool within the agriculture sector.
Robotic grippers have become integral across various industries, such as manufacturing, packaging, and logistics, particularly for tasks involving picking and placing. Recently, there’s been a growing interest in applying robotic grippers in agriculture for harvesting and packaging duties. Nevertheless, traditional robotic grippers often fail to accommodate the unique characteristics of different crops, which can be delicate and vary in shape and size. This demand for more adaptable robotics has increased as industries seek solutions capable of managing diverse objects.
Soft material robotic grippers have surfaced as a promising solution to these challenges. However, existing approaches for customizing these grippers to complex shapes rely heavily on intricate control and planning driven by data-based models. Such methods require extensive data, which limits their broad application. Additionally, incorporating a sensory system within a soft gripper necessitates complicated designs and advanced manufacturing techniques.
In response to these issues, a group of researchers from the Japan Advanced Institute of Science and Technology (JAIST), led by Associate Professor Van Anh Ho, Assistant Professor Nguyen Huu Nhan, and doctoral student Nguyen Thanh Khoi, have developed an innovative soft robotic gripper known as ROtation-based Squeezing grippEr (ROSE).
“ROSE draws inspiration from the way roses bloom to perform its grasping function. It presents a more straightforward method for harvesting in real-world farms by gently enveloping objects with a novel ‘wrinkling’ effect. Unlike traditional grippers, ROSE does not necessitate complicated control and planning to adjust to the varying shapes, sizes, and textures of agricultural items,” explains Professor Ho. The research team also utilized a simulation model to gain a thorough understanding of ROSE’s grasping mechanism and optimize its performance. Their findings were published in a special edition, RSS2023, of The International Journal of Robotics Research.
ROSE features a distinct cup-shaped chamber consisting of two thin layers of soft elastomer with a gap between the inner and outer layers. By rotating just the inner layer with an external motor, the layers deform. Specifically, this twisting action of the inner layer causes a mismatch in strain between the two layers, resulting in inward folds that mimic wrinkles, a process referred to as ‘wrinkling.’ This innovative mechanism effectively reduces the central space within ROSE, allowing it to gently grasp any items contained in this area.
To optimize this mechanism, the research team investigated the ‘wrinkling’ process using a finite element method-based simulation model. Their simulations revealed how different geometric features—such as thickness, diameter, and height—interrelate. Crucially, they discovered that the distribution of ROSE’s skin thickness significantly impacts its grasping efficiency. Consequently, they explored two different skin thickness strategies—linear and non-linear distributions—which notably enhanced ROSE’s performance compared to a uniform thickness design. Additionally, the simulations underscored the importance of the proportion between the diameter and height of the gripper. The simulation findings were corroborated by numerous experiments, confirming ROSE’s ability to execute tasks that typically challenge traditional grippers.
The researchers went on to showcase ROSE’s practical uses in agriculture by employing it to harvest strawberries and mushrooms. ROSE consistently achieved high success rates in trials of picking these crops, whether they were firm or delicate. It also managed to collect a bundle of mushrooms without damaging any of them, as long as the bundle’s size was suitable for the gripper’s grasp.
“ROSE represents one of the earliest grippers to leverage buckling deformation as a means of gripping, challenging the traditional perspective that buckling is undesirable. Furthermore, the practical implementation of ROSE in farming environments significantly alters the landscape of harvesting. Its capability to adjust to various textures and shapes enhances its effectiveness in these roles. This improvement not only boosts efficiency but could also help mitigate growing labor shortages in agriculture, especially in areas with aging populations,” emphasizes Professor Ho, highlighting ROSE’s potential.
This research signifies a major leap forward in robotic gripper technology. With its gentle yet adaptable grasping methods, ROSE could pave the way for a new era in automated farming.
