This article presents a versatile soft robotic gripper system whereby its fingers can be reconfigured into different poses such as scoop, pinch, and claw. This allows the gripper to efficiently and safely handle food samples of different shapes, sizes and stiffness such as uncooked tofu and broccoli floret. The 3D-printed fingers were tested to last up to 25 000 cycles without significant changes in the curvature profile and force output profile. A benchmark experiment was conducted to evaluate the performance of the gripper and state-of-the-art gripping solutions. Capability of versatile soft gripper was optimized by integrating vision and tactile sensing facilities. An object recognition system was developed to identify food samples such as potato, broccoli, and sausage. Position and orientation of food samples were identified and pick-and-place pathway was optimized to achieve the best gripping performance. Flexible tactile sensors were integrated into soft fingers and closed-loop force feedback control system was developed. This allowed the gripper to automatically explore and select the most stable grip pose for different food samples. Integration of vision and force feedback system ensure that objects detected by the system would be firmly gripped. The reconfigurable soft robotic gripper system has been demonstrated to perform high-speed pick-and-place tasks (∼3 s per item) with object recognition system, making it a potential solution to food and grocery supply chain needs.

This paper presents a hybrid tele-manipulation system, comprising of a sensorized 3-D-printed soft robotic gripper and a soft fabric-based haptic glove that aim at improving grasping manipulation and providing sensing feedback to the operators. The flexible 3-D-printed soft robotic gripper broadens what a robotic gripper can do, especially for grasping tasks where delicate objects, such as glassware, are involved. It consists of four pneumatic finger actuators, casings with through hole for housing the actuators, and adjustable base. The grasping length and width can be configured easily to suit a variety of objects. The soft haptic glove is equipped with flex sensors and soft pneumatic haptic actuator, which enables the users to control the grasping, to determine whether the grasp is successful, and to identify the grasped object shape. The fabric-based soft pneumatic haptic actuator can simulate haptic perception by producing force feedback to the users. Both the soft pneumatic finger actuator and haptic actuator involve simple fabrication technique, namely 3-D-printed approach and fabric-based approach, respectively, which reduce fabrication complexity as compared to the steps involved in a traditional silicone-based approach. The sensorized soft robotic gripper is capable of picking up and holding a wide variety of objects in this study, ranging from lightweight delicate object weighing less than 50 g to objects weighing 1100 g. The soft haptic actuator can produce forces of up to 2.1 N, which is more than the minimum force of 1.5 N needed to stimulate haptic perception. The subjects are able to differentiate the two objects with significant shape differences in the pilot test. Compared to the existing soft grippers, this is the first soft sensorized 3-D-printed gripper, coupled with a soft fabric-based haptic glove that has the potential to improve the robotic grasping manipulation by introducing haptic feedback to the users.

Soft robots have received much attention due to their impressive capabilities including high flexibility and inherent safety features for humans or unstructured environments compared with hard-bodied robots. Soft actuators are the crucial components of soft robotic systems. Soft robots require dexterous soft actuators to provide the desired deformation for different soft robotic applications. Most of the existing soft actuators have only one or two deformation modes. In this article, a new soft pneumatic actuator (SPA) is proposed taking inspiration from Kirigami. Kirigami-inspired cuts are applied to the actuator design, which enables the SPA to be equipped with multiple deformation modes. The proposed Kirigami-inspired soft pneumatic actuator (KiriSPA) is capable of producing bending motion, stretching motion, contraction motion, combined motion of bending and stretching, and combined motion of bending and contraction. The KiriSPA can be directly manufactured using 3D printers based on the fused deposition modeling technology. Finite element method is used to analyze and predict the deformation modes of the KiriSPA. We also investigated the step response, creep, hysteresis, actuation speed, stroke, workspace, stiffness, power density, and blocked force of the KiriSPA. Moreover, we demonstrated that KiriSPAs can be combined to expand the capabilities of various soft robotic systems including the soft robotic gripper for delicate object manipulation, the soft planar robotic manipulator for picking objects in the confined environment, the quadrupedal soft crawling robot, and the soft robot with the flipping locomotion.

THIS paper presents the development of a bidirectional fabric-based soft pneumatic actuator requiring low fluid pressurization for actuation, which is incorporated into a soft robotic gripper to demonstrate its utility. The bidirectional soft fabric-based actuator is able to provide both flexion and extension. Fabrication of the fabric actuators is simple as compared to the steps involved in traditional silicone-based approach. In addition, the fabric actuators are able to generate comparably larger vertical grip resistive force at lower operating pressure than elastomeric actuators and 3D-printed actuators, being able to generate resistive grip force up to 20N at 120 kPa. Five of the bidirectional soft fabric-based actuators are deployed within a five-fingered soft robotic gripper, complete with five casings and a base. It is capable of grasping a variety of objects with maximum width or diameter closer to its bending curvature. A cutting task involved bimanual manipulation was demonstrated successfully with the gripper. To incorporate intelligent control for such a task, a soft force made completely of compliant material was attached to the gripper, which allows determination of whether the cutting task is completed. To the authors' knowledge, this work is the first study which incorporates two soft robotic grippers for bimanual manipulation with one of the grippers sensorized to provide closed loop control.

Traditional actuators are usually heavy, expensive and require a complex multi-component mechanical structure to generate human-like movement. Therefore, we proposed a lightweight soft finger actuator (25g) that is powered by pneumatic means to perform the grasping tasks. The soft actuators were fabricated using 3D-printing and soft lithography techniques. 5 healthy subjects (3 males and 2 females; age: 25±2.5 years) were recruited and they were asked to wear a hand orthosis with actuator attached on index finger to evaluate the performance of the soft actuators. The flexion angle at metacarpo-phalangeal joint is 55.7±19.0°, proximal interphalangeal joint is 141.2±2.0°, and distal interphalangeal joint is 126.6±3.0°. Also, three finger actuators were used to create a prosthetic hand, which is capable of grasping and holding objects with different sizes and weights up to 600 g. These studies showed the possibility of deploying these soft finger actuators in hand orthotic and prosthetic devices.

In digital nerve repair surgery, handling the digital nerves using traditional forceps requires surgeons to be extremely cautious in order to minimize unintended iatrogenic nerve traumas. These damages are mainly caused by excessively forceful manipulation from metallic rigid forceps. Soft pneumatic actuators have been increasingly adopted to broaden the biomedical applications of conventional rigid structures due to their inherent excellent compliance and compressibility. However, the existing soft grippers pose barriers to be extended for digital nerve repair, due to their large prototype size or limited gripping force. In this paper, a new two-arm hybrid soft surgical gripper system is proposed to reduce the risk of excessive stress to nerves and facilitate surgeons' delicate nerve manipulation in digital nerve repair surgery. It consists of two hybrid soft surgical grippers, two stiffness-tunable positioning arms and a pedal-based control system. The inflated soft pneumatic gripping actuator is capable of providing compliant gripping and soft interaction with nerve tissues. This can prevent sudden over-gripping force stimulation. The ability to position two surgical grippers is provided by two stiffness-tunable arms combining six pneumatic locking actuators. The inflation of the soft pneumatic actuator is investigated using a theoretical model and finite element analysis. The cadaver experiments, rodent experiments and histopathological studies are conducted to validate that the new surgical gripper system is capable of completing the required digital nerve manipulation in digital nerve repair surgery and exhibits very low disruption to the nerve tissues.