Design Of Soft Gripper Research Articles

Novel Soft Gripper With Adjustable Performance Based on Blade Flexures

Abstract The design of soft grippers is challenging as the target objects to be handled involve a wide variety of sizes, shapes, and softness. Most grippers reported present drawbacks, e.g., complex control strategies for stiffness and force variation, inadequate adaptability to target shape variability, and complicated adaptation to manipulators, which in turn limit their implementation in applications such as harvesting. This paper presents a novel overlay soft gripper based on an assembling mechanism and passive soft structures, enabling the modification of grip size, orientation, and gripping force. This gripper can be assembled over a commercial robot-gripper taking the closing motion of this as the input to perform its closing motion. Input and output parameters are related by means of the displacement transmission mechanism which converts the closing motion of the robot-gripper into the closing motion of the overlay soft gripper. The gripping force can be modified through the change of stiffness, via adjustment of effective length using contact elements, of internal blade flexures. The displacement transmission mechanism works in two modes: as rigid-body mechanism without the contact elements and as rigid-body/flexible mechanism with the contact elements. The relationships between input and output parameters are obtained analytically for the case of rigid-body mechanism, and through finite element analysis simulations for the case of rigid-body/flexible mechanism. Relationships between input and output parameters are approximated with polynomial surfaces. Finally, physical prototypes are manufactured and assembled on their respective robot-grippers to qualitatively demonstrate their performance.

A Soft-Rigid Hybrid Gripper With Lateral Compliance and Dexterous In-Hand Manipulation

Soft grippers are receiving growing attention due to their compliance-based interactive safety and dexterity. Hybrid gripper with soft actuators enhanced by rigid constraints is receiving growing attention in soft gripper design. With rigid structural components actuated by soft actuators, they could achieve excellent grasping adaptability and payload while also being easy to model and control with conventional kinematics. However, existing works were mostly focused on achieving superior payload and perception with simple planar workspaces, resulting in far less dexterity compared with conventional grippers. In this work, we took inspiration from the human metacarpophalangeal (MCP) joint and proposed a new hybrid gripper design with eight independent muscles. It was shown that adding the MCP complexity was critical in enabling a range of novel features in the hybrid gripper, including in-hand manipulation, lateral passive compliance, as well as new control modes. A prototype gripper was fabricated and tested on our proprietary dual-arm robot platform with vision-guided grasping. With very lightweight pneumatic bellows soft actuators, the gripper could grasp objects over 20 times its weight with lateral compliance. Using the dual-arm platform, highly anthropomorphic dexterous manipulations were demonstrated using two hybrid grippers, from tug of war on a rigid rod to passing a soft towel between two grippers using in-hand manipulation. Matching the novel features and performance specifications of the proposed hybrid gripper, the underlying modeling, actuation, control, and experimental validation details were also presented, offering a promising approach to achieving enhanced dexterity, strength, and compliance in robotic grippers.

A novel multi objective constraints based industrial gripper design with optimized stiffness for object grasping

Soft gripper design is a rising area of research due of its great possibilities in automation. One difficult problem in robot design is the ability to grasp a broader variety of items with variable stiffness, forms, and sizes in a single gripper. An ideal soft robotic gripper design with variable stiffness was designed in this research as a grasping model. Its distinctiveness is found in the methods utilized for modelling actuators and in the shifting stiffness characteristics of silicon soft gripper. When modelling the actuator in this case, multi-objective functions like gripping displacement and force transmission ratio are taken into account, and the actuator functions are controlled by the MDF (multiple degrees of freedom). The precise stiffness needed to grasp the item is then chosen using an adaptive optimization method. This enhanced weight-based horse herd (IHH) optimization method carries out the stiffness adjustment based on actuation pressure. Additionally, the suggested soft robotic gripper with variable stiffness employs the adaptive level set (ALS) technique to build the gripping force model. Additionally, several validations are offered in relation to the outcomes for item gripping by the suggested soft gripper. This shown that the results of the created soft gripper excelled those of other methods. The developed ABBIRB 1410 robot gripper type may enhance the work cycle in industrial applications and performs object grabbing with dependability and speed. The experimental validations show that the developed gripper model provides an enhanced object grasp with a range of curvatures, delivering a maximum pulling force of 121.07 kPa at 50 kpa, 119.15 kPa for patterned pulling, and 45.05 kPa for non-patterned pulling. The designed gripper type has a curve with a minimum size of 1.1 mm and a maximum size of 218 mm. Additionally, the soft gripper for industrial applications is examined with variously sized and weighted items. The suggested gripper model achieved an RMSE performance of 2.9 and a Pearson correlation of 0.993.

Soft Gripper Design and Fabrication for Underwater Grasping

Underwater manipulation with current robotics technology is a challenging task with significant limits in versatility and robustness terms. Such functionality has tremendous potential covering a broad spectrum of applications, mainly replacing divers performing hazardous jobs. Soft robotics provides an efficient solution for operating in these scenarios and adapting to uncertain environmental conditions. This paper presents the design and fabrication of a simple, low-cost, and easily deployable soft gripper for underwater manipulation. We use modelling and simulation techniques for designing the soft fluidic elastomer actuators that compose the soft gripper and additive manufacturing techniques for rapid test cycles and validation. These techniques allow for a fast redesign depending on the application requirements. The proposal combines materials and fabrication techniques to take advantage of their strengths. We validate the feasibility and ability of the proposed soft gripper in a challenging underwater scenario using a subaquatic vehicle.

A methodology for design and simulation of soft grippers

Soft grippers are a growing type of end-effectors that are developed to balance out the simplicity and versatility of the grippers. Today, however, literature lacks a promising method for designing accurate, durable, and high-payload soft grippers. This paper therefore identifies the essential steps in order to design such grippers, and proposes a framework that links the essential steps in order to optimize the design of soft grippers according to the requirements. Finally, functionality and performance of the design grippers are experimentally verified and analyzed via a case study of a real industrial application.

Soft Origami Gripper with Variable Effective Length

Nature has evolved to shape morphing to adapt to complex environments while engaging with the surroundings. Inspired by this capability, robots are expected to be endowed with the ability to perform shape‐changing, thus interacting with complex environments. Herein, a soft origami actuator with variable effective length (VEL) is proposed to adapt to different objects. The actuator's VEL is realized by an origami structure and actuated by hybrid actuation of tendons and pneumatic pressure. The soft actuator yields motion combining both elongation and bending generated by the asymmetric Yorshimura origami structure. Then an adaptive gripper composed of four origami actuators with programmable effective length is fabricated and its effect on grasping performance is evaluated through both simulations and experiments. Results show that the gripper can grip objects of different shapes, weights, sizes, and textures. This research may shed light on a new soft gripper design using origami structure for the environment's self‐adaptability.

Design of Soft Grippers with Modular Actuated Embedded Constraints

Underactuated, modular and compliant hands and grippers are interesting solutions in grasping and manipulation tasks due to their robustness, versatility, and adaptability to uncertainties. However, this type of robotic hand does not usually have enough dexterity in grasping. The implementation of some specific features that can be represented as “embedded constraints” allows to reduce uncertainty and to exploit the role of the environment during the grasp. An example that has these characteristics is the Soft ScoopGripper a gripper that has a rigid flat surface in addition to a pair of modular fingers. In this paper, we propose an upgraded version of the Soft ScoopGripper, developed starting from the limits shown by the starting device. The new design exploits a modular structure to increase the adaptability to the shape of the objects that have to be grasped. In the proposed device the embedded constraint is no rigid neither unactuated and is composed of an alternation of rigid and soft modules, which increase versatility. Moreover, the use of soft material such as thermoplastic polyurethane (TPU) reduces the risk of damage to the object being grasped. In the paper, the main design choices have been exploited and a finite element method (FEM) analysis through static simulation supports a characterization of the proposed solution. A complete prototype and some preliminary tests have been presented.