Cheetah, Gecko and Spiders Inspire Robotic Designs
Posted in: mit, R&D and Inventions, Robots, Today's Chili
A cheetah can run faster than any other animal. A gecko’s feet can stick to almost any surface without using liquids or surface tension. And some roaches scurry at nearly 50 times their body length in one second, which, scaled up to human levels, can be around 200 miles an hour.
The wonders of the animal kingdom are not just for fans of National Geographic. Robotic designer Sangbae Kim, a professor at the Massachusetts Institute of Technology, is trying to understand how he can take some of the mechanisms animals use and replicate them in robots.
The animal kingdom provides the best ideas for creating mobile robots, says Kim. Locomotion and movement are the core parts of an animal’s life. “Animals have to find food, shelter; move towards water or away from a predator,” he says.
“Moving is one of their biggest functions, and they do it very well. That’s why ideas from nature are very important for a robotic designer like me.”
Mechanical design derived from biological models is something Kim has been working on for years, first at Stanford University and now at MIT. The simplification and adaptation of the fundamental design principles seen in animals has led to the creation of his bio-inspired robots.
Among the robots Kim and his team have designed are the Stickybot, a robot that has foot pads based on a gecko’s feet, and iSprawl, a robot whose motion is inspired from cockroaches.
Kim’s latest project is a robot inspired by the cheetah. The idea is build a prototype robot from a lightweight carbon-fiber-foam composite that can run at the cheetah’s speed of 70 miles per hour.
It’s an ambitious project. Current wheeled robots are efficient, but can be slow in rough terrains. For instance, iRobot’s PackBot, which is used by the U.S. military, can only travel at speeds of up to 5.8 miles per hour.
“Most wheeled robots today can do very well on flat surfaces, but they are slow,” says Kim. That’s why he’s looking to the cheetah for ideas. The cheetah has an extremely flexible backbone that gives extra speed or force to its running motion.
Over the next 18 months, Kim and four MIT graduate students will start building and testing prototypes. The first step will be to create a computer model to calculate the optimal limb length, weight, gait and torque of the hip and knee joints.
The biggest challenge in this project won’t be the structure, but getting enough power from a motor to get to the desired speed quickly, says Kim.
Before the robotic cheetah came Stickybot, a mechanical lizard-like robot that takes its inspiration from the gecko. Geckos can climb walls at almost the same speed — of about 1 meter per second — at which they run on the ground. This remarkable ability makes it the perfect animal to draw upon to create a climbing robot, says Kim.
The secret to the gecko’s agility is that it uses a phenomenon called directional adhesion, or stickiness in just one direction, to adhere to walls.
“The gecko’s feet can detach very easily as it moves forward,” says Kim. “If you take normal sticky tape and press it to the wall, you will find it is tough to detach it quickly. Directional adhesion solves that problem.”
The pads of a gecko’s feet are covered with tiny hairs called setae and spatulae that can be up to one-thousandth the width of a human hair. The hairs cling to surfaces using molecular interactions known as the Van der Waals force. The force helps support the gecko’s weight as it scrambles up vertical surfaces.
Kim has tried to recreate that idea for the Stickybot. The Stickybot’s feet is covered with hairs made of rubber silicone. The rubber is thicker than those on a gecko’s paw, however, which limits the robot’s abilities. It can only climb extremely smooth surfaces such as glass, acrylic or a whiteboard.
Kim says his team is working on refining the Stickybot so that it can adapt to climbing on walls with uneven textures.
If the Stickybot can be improved, there are plenty of applications for it, such as repairing of underwater oil pipelines or even window washing.
