A Variable Stiffness Soft Gripper Based on Rotational Layer Jamming.

This article presents the design and fabrication of a variable stiffness soft gripper based on layer jamming. Traditional layer jamming units have some limitations, such as complicated multistep fabrication, difficulties in system integration, and diminishing in stiffen effect. In this article, a variable stiffness soft gripper is proposed based on the rotational jamming layers to reduce the slippery phenomenon between layers. To fabricate the proposed complex design, a two-step fabrication method is presented. First, multimaterial 3D printing is applied to directly print out the soft finger body with jamming layers. Second, mold casting is used to fabricate the outer vacuum chamber. The proposed gripper contains a main framework and three identical variable stiffness soft fingers. To demonstrate the effectiveness of the design, the soft gripper is mounted on a robotic arm to test its ability of grasping heavy objects while following complex grasping trajectory. The gripper can successfully grasp an object up to 360 g. Grasping robustness of the proposed gripper can be guaranteed when the robotic arm is moving at acceleration up to 7 m/s2. The results prove that the proposed design of the soft gripper can improve the grippers grasping robustness during high-speed movement.

An Evaluation System of Robotic End-Effectors for Food Handling.

Owing to Japan's aging society and labor shortages, the food and agricultural industries are facing a significant demand for robotic food handling technologies. Considering the large variety of food products, available robotic end-effectors are limited. Our primary goal is to maximize the applicability of existing end-effectors and efficiently develop novel ones, and therefore, it is necessary to categorize food products and end-effectors from the viewpoint of robotic handling and establish their relationships through an effective evaluation approach. This study proposes a system for evaluating robotic end-effectors to identify appropriate ones and develop new ones. The evaluation system consists of food categorization based on food properties related to robotic handling, categorization of robotic end-effectors based on their grasping principles, a robotic system with visual recognition based on Robot Operating System 2 (ROS 2) to conduct handling tests, a scoring system for performance evaluation, and a visualization approach for presenting the results and comparisons. Based on food categorization, 14 real food items and their corresponding samples were chosen for handling tests. Seven robotic end-effectors, both commercialized and under development, were selected for evaluation. Using the proposed evaluation system, we quantitatively compared the performance of different end-effectors in handling different food items. We also observed differences in the handling of real food items and samples. The overall performance of an end-effector can be visualized and quantitatively evaluated to demonstrate its versatility in handling various food items.

Application of High-Photoelasticity Polyurethane to Tactile Sensor for Robot Hands.

We developed a tactile sensor for robot hands that can measure normal force (FZ) and tangential forces (FX and FY) using photoelasticity. This tactile sensor has three photodiodes and three light-emitting diode (LED) white light sources. The sensor is composed of multiple elastic materials, including a highly photoelastic polyurethane sheet, and the sensor can detect both normal and tangential forces through the deformation, ben sding, twisting, and extension of the elastic materials. The force detection utilizes the light scattering resulting from birefringence.

A Scooping-Binding Robotic Gripper for Handling Various Food Products.

Food products are usually difficult to handle for robots because of their large variations in shape, size, softness, and surface conditions. It is ideal to use one robotic gripper to handle as many food products as possible. In this study, a scooping-binding robotic gripper is proposed to achieve this goal. The gripper was constructed using a pneumatic parallel actuator and two identical scooping-binding mechanisms. The mechanism consists of a thin scooping plate and multiple rubber strings for binding. When grasping an object, the mechanisms actively makes contact with the environment for scooping, and the object weight is mainly supported by the scooping plate. The binding strings are responsible for stabilizing the grasping by wrapping around the object. Therefore, the gripper can perform high-speed pick-and-place operations. Contact analysis was conducted using a simple beam model and a finite element model that were experimentally validated. Tension property of the binding string was characterized and an analytical model was established to predict binding force based on object geometry and binding displacement. Finally, handling tests on 20 food items, including products with thin profiles and slippery surfaces, were performed. The scooping-binding gripper succeeded in handling all items with a takt time of approximately 4 s. The gripper showed potential for actual applications in the food industry.

Challenges and Opportunities in Robotic Food Handling: A Review.

Despite developments in robotics and automation technologies, several challenges need to be addressed to fulfill the high demand for automating various manufacturing processes in the food industry. In our opinion, these challenges can be classified as: the development of robotic end-effectors to cope with large variations of food products with high practicality and low cost, recognition of food products and materials in 3D scenario, better understanding of fundamental information of food products including food categorization and physical properties from the viewpoint of robotic handling. In this review, we first introduce the challenges in robotic food handling and then highlight the advances in robotic end-effectors, food recognition, and fundamental information of food products related to robotic food handling. Finally, future research directions and opportunities are discussed based on an analysis of the challenges and state-of-the-art developments.

Relationship between Photoelasticity of Polyurethane and Dielectric Anisotropy of Diisocyanate, and Application of High-Photoelasticity Polyurethane to Tactile Sensor for Robot Hands.

Eight types of polyurethane were synthesized using seven types of diisocyanate. It was found that the elasto-optical constant depends on the concentration of diisocyanate groups in a unit volume of a polymer and the magnitude of anisotropy of the dielectric constant of diisocyanate groups. It was also found that incident light scattered when bending stress was generated inside photoelastic polyurethanes. A high sensitive tactile sensor for robot hands was devised using one of the developed polyurethanes with high photoelasticity.

A Fully Multi-Material Three-Dimensional Printed Soft Gripper with Variable Stiffness for Robust Grasping.

Multi-material three-dimensional (3D) printing has provided the possibility of direct 3D printing of soft actuators with high complexity and functionality in a fast and easy fabrication process. In this article, we present the design of a multi-material 3D printed variable stiffness soft robotic gripper to ensure grasping robustness during high acceleration. The proposed gripper contains two identical soft fingers, with each finger including a pneumatic actuator and an integrated layer jamming unit. Prototypes of the soft finger, with material hardness transfer from the soft-bodied actuator to the hard pneumatic tubing and layer jamming unit, are fully fabricated by one-step 3D printing. A multi-material 3D printer, Objet350Connex, is used to directly print out the whole finger without the need for an additional casting process. The printed soft finger has a complex inner geometry, which integrates a small, light, and flexible layer jamming unit. The proposed finger can freely deform at low stiffness and maintain its grasping robustness at high stiffness during high acceleration. To demonstrate the effectiveness of the proposed design, the gripper is mounted on a robotic arm to evaluate its grasping robustness. With the aid of the integrated layer jamming unit, grasping robustness can be guaranteed when the robotic arm is moving at acceleration up to 8 m/s2. The results show that the proposed soft gripper is an effective design, which can guarantee grasping robustness during high acceleration.

Comparison of different soft grippers for lunch box packaging.

Automating the lunch box packaging is a challenging task due to the high deformability and large individual differences in shape and physical property of food materials. Soft robotic grippers showed potentials to perform such tasks. In this paper, we presented four pneumatic soft actuators made of different materials and different fabrication methods and compared their performances through a series of tests. We found that the actuators fabricated by 3D printing showed better linearity and less individual differences, but showed low durability compared to actuators fabricated by traditional casting process. Robotic grippers were assembled using the soft actuators, and grasping tests were performed on soft paper containers filled with food materials. Results suggested that grippers with softer actuators required lower air pressure to lift up the same weight and generated less deformation on the soft container. The actuator made of casting process with Dragon Skin 10 material lifted the most weight among different actuators.

Design and Validation of Exoskeleton Actuated by Soft Modules toward Neurorehabilitation-Vision-Based Control for Precise Reaching Motion of Upper Limb.

We demonstrated the design, production, and functional properties of the Exoskeleton Actuated by the Soft Modules (EAsoftM). Integrating the 3D printed exoskeleton with passive joints to compensate gravity and with active joints to rotate the shoulder and elbow joints resulted in ultra-light system that could assist planar reaching motion by using the vision-based control law. The EAsoftM can support the reaching motion with compliance realized by the soft materials and pneumatic actuation. In addition, the vision-based control law has been proposed for the precise control over the target reaching motion within the millimeter scale. Aiming at rehabilitation exercise for individuals, typically soft actuators have been developed for relatively small motions, such as grasping motion, and one of the challenges has been to extend their use for a wider range reaching motion. The proposed EAsoftM presented one possible solution for this challenge by transmitting the torque effectively along the anatomically aligned with a human body exoskeleton. The proposed integrated systems will be an ideal solution for neurorehabilitation where affordable, wearable, and portable systems are required to be customized for individuals with specific motor impairments.

Post-transplant early recurrent proteinuria in patients with focal glomerulosclerosis--angiotensin II immunostaining and treatment outcome.

We reviewed the transplantation data and results of histopathological studies with additional angiotensin II (AII) immunostaining of renal graft biopsies of nine cases (10 grafts) with recurrent proteinuria and three controls without recurrent proteinuria that received renal transplantation for primary focal segmental glomerulosclerosis (FSGS) between 1986 and 2002. Recurrent FSGS was confirmed in six grafts from nine cases by light microscopy. In cases with recurrent proteinuria, loss of graft function was noted in all six renal grafts received between 1986 and early 1992 but in none of four grafts received between late 1992 and 2002. Two of four patients of the late group but none of those of the early group received angiotensin converting enzyme (ACEI) or angiotensin II receptor blocker (ARB) with plasma exchange (PE). In control cases without proteinuria, AII immunostaining was detected in tubules but not in glomeruli in 1-hour biopsies as well as later on. In cases with recurrent proteinuria, AII immunostaining was detected in both tubules and glomeruli, although glomerular AII staining was not observed in 1-hour biopsies. Our results suggest that effective treatment of post-transplantation recurrent FSGS requires ACEI or ARB with PE in the absence of another etiology.

A male patient with steroid-dependent nephrotic syndrome for 25 years and obesity-associated focal segmental glomerulosclerosis.

An obese male patient with steroid-dependent nephrotic syndrome since age 6 years had a thirty-third relapse at the age of 29 years. Renal biopsy showed focal segmental glomerulosclerosis. Proteinuria disappeared after treatment with prednisolone. He went into complete remission and renal function remained normal at the age of 31 years. Focal segmental glomerulosclerosis associated with obesity was suspected. Long-term follow-up with renal biopsy is necessary in obese children with steroid-dependent nephrotic syndrome.

Alport syndrome-like basement membrane changes in Frasier syndrome: an electron microscopy study.

Frasier syndrome (FS) is a rare disease characterized by male pseudohermaphroditism and slowly progressing nephropathy. FS originates from heterozygous mutation in the intron 9 splicing donor site of Wilms' tumor suppressor gene (WT1). Focal segmental glomerular sclerosis is common in FS, but there have not been so many detailed pathologic investigations. The authors examined the kidneys of 3 patients with FS. The results showed that nephropathy started as mesangial proliferative glomerulonephritis, and later a concomitant focal segmental lesion developed. In all cases, electron microscopy results showed widespread thinning, splitting, and lamellation of the glomerular basement membrane, which mimicked hereditary nephritis. Throughout adulthood, WT1 protein expresses on glomerular podocytes. Recent reports described that podocytes expressing WT1 play an important role in maintaining the glomerular basement membrane. Hereditary nephritis-like glomerular basement membrane findings in FS suggest that one of the important functions of podocytes is to form and maintain the glomerular basement membrane.