Researchers from the University of California, San Diego, created a four-legged robot that is powered without any electronics. The robot uses a constant source of pressurized air for all of its functions, and could be used for low-cost robotics in entertainment and in environments where electronics cannot function, like MRI machines or mine shafts.

Most robotics are powered by pressurized air and controlled by electronic circuits. Typically, robotics need complex components, including circuit boards, valves and pumps. Often electronics are placed outside of a robot’s body that act as the brain and nervous system, which becomes bulky and expensive.Engineers at the University of California San Diego have created a four-legged soft robot that doesn't need any electronics to work. The robot only needs a constant source of pressurized air for all its functions, including its controls and locomotion systems. Source: University of California San DiegoEngineers at the University of California San Diego have created a four-legged soft robot that doesn't need any electronics to work. The robot only needs a constant source of pressurized air for all its functions, including its controls and locomotion systems. Source: University of California San Diego

The new robot is controlled by a lightweight, low-cost system of pneumatic circuits, tubes and soft valves on the robot. It can walk on command and in response to environmental signals. This computational power mimics mammalian reflexes driven by a neural response from the spine rather than the brain.

Central pattern generators on the robot are made of simple elements that generate rhythmic patterns to control motions like walking and running. The robot's mimic generator functions are powered by valves that act as oscillators and the generator controls how the pressurized air enters to power muscles in the robot’s limbs. The researchers also built a component that creates the robot’s gait -- inspired by sideneck turtles -- by delaying the injection of air into robot's legs.

The robot is equipped with simple mechanical sensors. Soft bubbles filled with fluid flow to the end of booms which are protruding from the robot’s body. When the bubbles are depressed, fluid fills a valve, causing it to change direction. There are three valves that act as inverters that cause a high-pressure state to spread around the air to a powered circuit with a delay at each inverter.

Each leg has three degrees of freedom and is powered by three muscles. The legs are angled downward at a 45-degree angle and are made of three parallel-connected pneumatic cylindrical chambers with bellows. When a chamber is pressured, the limb bends in the opposite direction. The chambers provide multi-axis bending and walking.

The soft valves switch direction for the limb rotation between counterclockwise and clockwise. This valve acts as a latching double pole double throw switch, which is a switch with two inputs and four outputs. This mechanism is like taking two nerves and swapping collections in the brain.

The team has big plans for their little robot. They want to improve the robot’s gait so it can walk on natural terrains, uneven surfaces and navigate over obstacles. They say the robot needs a more sophisticated network of sensors and a more complex pneumatic system.

A paper on this new robot was published in Science Robotics.