Diaphragm-Type Pneumatic-Driven Soft Grippers for Precision Harvesting

Abstract

Soft actuator technology and its role in robotic manipulation have been rapidly gaining ground. However, less attention has been given to the potential advantages of its application to the agricultural sector, where soft robotics may be a game changer due to its greater adaptability, lower cost and simplicity of manufacture. This article presents a new design approach for soft grippers based on modules that incorporate the concept of bellows and combine it with the versatility and replicability of a 3D printed structure. In this way, the modules can be freely configured to obtain grippers adaptable to crops of different diameters. Furthermore, the definition of a method to determine the soft grippers features is also presented, with the aim of serving as the basis for a future benchmarking study on soft actuators. The experimental tests carried out demonstrated the feasibility and capability of the end-effectors to manipulate various fruits, ensuring a sufficient contact area for the safe handling of the targets and avoiding damaging the products.

Intelligent Soft Robotic Grippers for Agricultural and Food Product Handling: A Brief Review with a Focus on Design and Control

“…As mentioned in the introduction, SPAs with specific pneumatic channel designs can also function as tentacle, [13,14] finger, [100][101][102][103][104] hand, [102] and envelope [17] grippers. These actuators are activated by inflating selected channels, causing them to flex in the opposite direction of the channel location [103,104] (Figures 5e,f ).…”

“…Additionally, other soft grippers with unique structures have also been developed, relying on expansion to grasp targets with specified channel designs. In contrast to the one-channel soft actuators discussed previously, which bend toward the thicker wall to grasp targets, some researchers have chosen to use the thinner wall to make contact with objects, resulting in slight deformation but strong support and clipping capabilities, This design approach has demonstrated good shape anastomosis capabilities, [100,101] as shown in Figure 5h,i. Moreover, researchers have explored the use of expanding deformation and circumferential arrangement of channels to achieve enveloping grasping, as PneuNets [34] Ecoflex30, PDMS 7-28 kPa Egg, live mouse Light weight Not suitable for heavy objects…”

“…These grippers exhibit high flexibility and have been successfully used to handle various agricultural products such as tomatoes, [117] apples, [118] mangos, pears, [119] eggs, [120,121] peppers, pomegranates, and even large items like watermelon and pumpkin using large grippers. [101] However, there are two shortcomings that limit the use of pneumatic grippers for agricultural products. First, the limited contact area may result in an insecure grasping state, as these grippers typically only use their tips to hold the target.…”

“…Membrane-based pneumatic soft gripper [100] Dragonskin20 0-30 kPa 5.63 N Cylinders Uniform deformation Limited workspace Diaphragm-type pneumatic soft gripper [101] PDMS 0-50 kPa 100 N Eggplant, pumpkin watermelon, pepper, pear.…”

“…Copyright 2022, IEEE). i) Diaphragm soft grippers with a circular chamber [ 101 ] (Reproduced with permission. Copyright 2021, MDPI).…”