In industrial settings, robots often are used for tasks that require repetitive grasping and manipulation of objects. The end of a robot where a human hand would be found is known as an end effector or gripper. Researchers have developed a humanoid hand design that is a soft-hard hybrid flexible gripper. It can generate larger grasping force than a traditional pure, soft hand and simultaneously be more stable for accurate manipulation of heavier objects.

Generally, soft-hand grippers — which are used primarily in settings where an object may be fragile, light, and irregularly shaped — present several disadvantages including sharp surfaces, poor stability in grasping unbalanced loads, and relatively weak grasping force for handling heavy loads.

When designing the new model, the team took into consideration a number of human-environment interactions, from fruit picking to sensitive medical care. They identified that some processes require a safe but firm interaction with fragile objects; most existing gripping systems are not suitable for these purposes.

The design novelty resulted in a prototype demonstrating the merits of a responsive, fast, lightweight gripper capable of handling a multitude of tasks that traditionally required different types of gripping systems.

Each finger of the soft humanoid hand is constructed from a flexible, hybrid pneumatic actuator (FHPA) driven to bend by pressurized air, creating a modular framework for movement in which each digit moves independently of the others. Traditional rigid grippers for industrial applications are generally made of simple but reliable rigid structures that help in generating large forces, high accuracy, and repeatability. The new hand has demonstrated adaptability and compatibility in grasping complex-shaped and fragile objects while simultaneously maintaining a high level of stiffness for exerting strong clamping forces to lift heavy loads.

The FHPA is composed of both hard and soft components built around a unique structure of actuated air bladders and a bone-like spring core that combines the advantages of the deformability, adaptability, and compliance of soft grippers while maintaining the large output force originated from the rigidity of the actuator.

The prototype can be useful in industries such as fruit picking, automated packaging, medical care, rehabilitation, and surgical robotics. The team hopes to combine the hybrid gripper with soft arm models to more accurately mimic precise human actions.

For more information, contact Caroline Brooks at This email address is being protected from spambots. You need JavaScript enabled to view it.; 517-432-0920.


Motion Design Magazine

This article first appeared in the December, 2020 issue of Motion Design Magazine.

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