How many robots does it take to screw in a lightbulb? A new hybrid robot combines flexibility and strength to complete this task.
How many robots does it take to screw in a lightbulb? It’s not as simple as it sounds. Researchers at Northeastern University have developed a robot that’s both flexible and sensitive enough to handle a lightbulb while applying the right amount of torque, solving this tricky challenge.
Researchers have developed a new type of robot that combines the advantages of both rigid and soft robots. This innovative design creates a robot that is flexible, extendable, and compliant, resembling the movement of an elephant trunk or an octopus tentacle, while also being capable of applying torque like a traditional industrial robot.
Currently, robots generally fall into two categories: rigid and soft. Rigid robots are often used in industrial settings where they perform precise tasks at high speeds. Due to their strength and speed, they are typically enclosed in safety cages to prevent harm to humans. These robots excel at tasks requiring significant torque, such as spinning or tightening objects.
Soft robots, on the other hand, are inspired by biological organisms. Their flexible structures allow them to navigate complex environments and interact safely with people. Unlike rigid robots, a soft robot’s impact would be more like a gentle slap than a serious injury, making them ideal for applications requiring close human interaction.
By rethinking robot materials and design, researchers have created a hybrid solution that enhances both safety and functionality in robotic applications.
A rigid machine has the necessary torque, while a soft robot offers the flexibility and maneuverability to handle delicate tasks like screwing in a lightbulb. Recent research has introduced a hybrid robot that combines both qualities using a new material inspired by constant-velocity (CV) joints, similar to those connecting a car’s wheel to its axle.
While traditional CV joints are made from rigid components, this innovative material is soft, flexible, and bendable. Instead of relying on changes in chemistry like many soft robots, this design focuses on shaping materials to achieve desired movements. The result is a versatile robot arm — and a fresh take on how many robots it takes to screw in a lightbulb.
Reference: Molly Carton et al, Bridging hard and soft: Mechanical metamaterials enable rigid torque transmission in soft robots, Science Robotics (2025). DOI: 10.1126/scirobotics.ads0548
