Engineers Design Humanoid Hand for Gripping Fragile Objects

A team of engineers at Michigan State University has designed and developed a humanoid hand that is much better at carrying out delicate tasks compared to the ones traditionally used. The new robotic hand can handle objects that are fragile, light, and irregularly shaped.

Robots in the Industrial Setting

The industrial setting is one of the areas most impacted by developments in robotics, as the technology is often used for the repetitive grasping and control of objects. 

The area of the robot where a human hand would be located is called an end effector or gripper, and that was the focus of the new research, which was published in Soft Robotics and is titled “Soft Humanoid Hands with Large Grasping Force Enabled by Flexible Hybrid Pneumatic Actuators.”

Changyong Cao was the lead author and is the director of the Laboratory for Soft Machines and Electronics at MSU. Cao is also an assistant professor in Packaging, Mechanical Engineering, and Electrical and Computer Engineering. 

“The novel humanoid hand design is a soft-hard 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,” said Cao. 

Soft-Hand Grippers

Soft-hand grippers are normally utilized whenever an object is fragile, light, and irregularly shaped. However, they have many downsides, including sharp surfaces, poor grasping stability when unbalanced loads are targeted, and a weaker grasping force for heavy loads. 

Cao and his team looked toward human-environment interactions, including fruit picking and sensitive medical care, when designing the new humanoid hand. They determined that most gripping systems are not effective in the areas where they are most needed, such as tasks that require firm interaction with fragile objects.

According to the team, the prototype demonstrated a responsive, fast, and lightweight gripper that could handle various tasks. 

The different fingers on the soft humanoid hand are made from a flexible hybrid pneumatic actuator, also called FHPA, and their bend is controlled by pressurized air. This process results in each digit being able to be controlled independently from 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,” Cao said. “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.”

The FHPA

The FHPA consists of hard and soft components.

“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 said.

According to Cao, the newly developed humanoid hand could be used in tasks like fruit picking, automated packaging, medical care, and surgical robotics.

The team will now look to combine the work with Cao’s previous developments, which include ‘smart’ grippers. They also want to integrare printed sensors in the gripping material and combine the hybrid gripper with ‘soft arms’ models, which would lead to a more accurate representation of human actions among robots.