A team of engineers at Michigan State University in East Lansing have designed and developed a novel device resembling a human hand for robots with specialized tasks.
In industrial settings, robots often are used to perform repetitive tasks. The device at the end of a robot that grasps and manipulates objects is known as an end effector or gripper. Soft-hand grippers generally have sharp surfaces, poor stability in grasping unbalanced loads, and relatively weak grasping force for handling heavy loads.
MSU engineers have designed a humanoid hand that has safe but firm interaction with fragile objects. The team is led by Changyong Cao, the director of the Laboratory for Soft Machines and Electronics and an assistant professor in the packaging, mechanical engineering, and electrical and computer engineering.
“The novel humanoid hand design 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 than other counterparts used for heavier objects,” says Cao.
The team made a prototype to demonstrate the merits of a responsive, fast, lightweight gripper capable of handling tasks that traditionally require different types of gripping systems.
Each finger of the soft humanoid hand is constructed from a flexible hybrid pneumatic actuator – or FHPA – driven by pressurized air, creating a framework in which each digit moves independently of the others.
The FHPA is composed of both hard and soft components, built around a structure of actuated air bladders and a bone-like spring core.
“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,” Cao says. “The proposed soft humanoid hand has demonstrated excellent 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.
“They combine the advantages of the deformability, adaptability, and compliance of soft grippers while maintaining the large output force originated from the rigidity of the actuator.”
Cao believes the prototype can be useful in industries such as fruit picking, automated packaging, medical care, rehabilitation, and surgical robotics.
The team hopes to combine its advances with Cao’s recent work on “smart” grippers, integrating printed sensors in the gripping material. By combining the hybrid gripper with “soft arms” models, the researchers aim to more accurately mimic precise human actions.
The research was partially funded by the U.S. Department of Agriculture-National Institute of Food and Agriculture, MSU Strategic Partnership Grant, National Natural Science Foundation of China, and an MSU Startup Grant.