We all know it for a fact that nature has proven to be the greatest inspiration for many inventions. Scientists study the characteristics of the things found in nature and come up with amazing technologies. One such technology that the scientists have come up with is the Quadruped Robotics, inspired by the gait pattern of the quadruped animals.
The last 3 decades have seen the rise of mobile robots with its applications varying from rescue operations to space explorations and much more. Mobile robots can be classified into 3 categories: Tracked Robots, Wheeled Robots and Legged Robots. Though wheeled and tracked robots can work in plain terrain, they find it difficult to work in complex terrain. Legged robots, on the other hand, find it quite easy to move around the different terrains on the earth’s surface just like humans and animals.
Animals use their four legs to move fast across different terrains with high speed and great efficiency depending on the environmental conditions. Thus, in the field of robotics, quadruped robots have become the best choice of all legged robots. The four legs of the robot can easily be designed, controlled and maintained when compared to the two or six legs.
Now, let’s just travel back in time to know more about the evolution of quadruped robots.
Lambda Mechanism
Scientists and researchers in the early 1900’s, devoted their time to study the leg mechanism of the four-legged robots. Pafnuty Chebyshev, the famous Russian mathematician developed the first walking mechanism in 1870. This mechanism resembled the Greek letter Lambda hence the name Lambda Mechanism.
This device could walk dynamically on flat terrain only and does not have independent leg motion. Later this mechanism got incorporated into two other machines which are: MELWALK & DANTE.
The California Horse
The quadruped robot named “Phony pony” was constructed in the 1960s at the University of California.
It was also known as “The California Horse“. Each leg of this robot had two identical rotary joints which were electrically actuated and was capable of producing several gait patterns like walk, trot, etc.
Each of its feet was in the inverted T shape because of which it was able to maintain a stationary upright gait.
TITAN Series
Hirose’s TITAN series was the most exceptional achievement in the field of quadruped robotics. He first developed the TITAN III quadruped robot. It was the world’s first climbing robot which is equipped with an intelligent program, a toe tactile sensor (A device that measures information from the physical interaction with its environment) and an attitude sensor (An instrument for determining the angular deviations of the axes from a preset direction). Later in 1986, TITAN IV was developed with extra features like the crawl being converted into a trot by gradually increasing the speed. TITAN V and TITAN VI were developed for purposes like weight mechanism, dynamic walking and so on. As for TITAN VII, it was developed mainly for assisting the construction work at steep slopes like moving scaffolds (A raised wooden platform). Moving further in the series, TITAN VIII which is considered to be the most popular among all has been designed with each leg having 3 degrees of freedom. It uses a “wire driven driving system”. This leg mechanism has four wires. With time, the TITAN series also expanded with extra features being added.
The latest quadruped robot in the TITAN series is TITAN XIII which is a sprawling type quadruped robot. It can walk efficiently with 1.38m/s speed and is powered by a battery. These robots weighed 7.5kg each and became unstable when the stride period(the time elapsed between the first contact of two consecutive footsteps of the same foot) exceeded 0.9s.
Image Credits: SUZUMORI ENDO LAB/TOKYO TECH
Modern-Day Quadruped Robots
Boston Dynamics a spin-off from the Massachusetts Institute of Technology (MIT) is an American engineering and robotics design company founded in 1992. Discussing quadruped robotics without mentioning the contribution of Boston Dynamics to this field would just be unfair and truly incomplete. It is best known for its development of a series of highly efficient mobile robots.
The Little Dog, a small quadruped robot that was launched in 2010 had four legs each powered by three electric motors. This robot was developed for DARPA (The Defense Advanced Research Projects Agency). The robot is capable of climbing and dynamic locomotion gaits.
In 2013, the Massachusetts Institute of Technology developed a highly efficient quadruped robot named MIT Cheetah. This 70-pound ‘cheetah’ robot was found to waste very little energy as it trotted at 5mph continuously for up to an hour and a half. Lightweight electric motors were set onto the shoulders of the robot which produced high torque with very little heat being wasted.
The latest version of MIT Cheetah is springy and light on its feet. Weighing just about 20 pounds, this four-legged robot can bend and swing its legs wide which enables it to walk either right side up or upside down. It can even trot over uneven terrain about twice as fast as an average person’s walking speed.
Yet another quadruped robot was introduced on the 23rd of March 2016 by Boston Dynamics named Spot. This four-legged canine-inspired Spot weighs only 25kg. The company highlights it as the quietest robot they have ever built. On 23rd June 2020, a lone spot ‘Zeus’ was used by SpaceX at their Boca Chica Starship test site to help carry the sub-cooled liquid nitrogen and to inspect the potentially dangerous sites around the launchpad.
Boston Dynamics is undoubtedly professional in developing quadruped robots. But there are many other companies trying to pitch in their bit of contribution to this field. One among them is Xiaomi.
On the 10th of August 2021, Xiaomi launched its new bio-inspired quadruped robot named the CyberDog. The CyberDog is capable of conducting a range of high-speed movements up to 3.2m/s and actions like backflips. It is equipped with 11 high-precision sensors which include touch sensors, a camera, ultrasonic sensors GPS modules and more. This provides instant feedback and guides its movements. The CyberDog is also capable of analyzing its environment in real-time, create navigational maps, plot its destination and avoid obstacles. With the help of face recognition tracking installed, it is also capable of following its owner. The users can use voice assistants to command and control the CyberDog.
As we have seen all through, the quadruped robots are evolving over time and with each new series, we can see that they are making significant progress. Further studies of the design are going on in this field so as to develop more cooperative and friendly robots.
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Also, Have a Look at: ROBOTICS: The Emerging Technology
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