{"id":25098,"date":"2018-07-17T10:22:00","date_gmt":"2018-07-17T14:22:00","guid":{"rendered":"https:\/\/www.tun.com\/blog\/?p=25098"},"modified":"2022-03-16T10:41:46","modified_gmt":"2022-03-16T14:41:46","slug":"robotic-cheetah-emergency-responder","status":"publish","type":"post","link":"https:\/\/www.tun.com\/blog\/robotic-cheetah-emergency-responder\/","title":{"rendered":"Robotic Cheetah to Act as Emergency Responder"},"content":{"rendered":"

The robotic cheetah is one of the most popular inventions MIT has developed in the 21st century. Its design, speed, size, strength and jumping ability has made it a fan favorite and given it real-world applications. <\/span><\/p>\n

Now, a <\/span>third generation robot<\/span><\/a>, named the Cheetah 3, can travel swiftly across rough terrain, climb up stairs covered in debris, and easily recover its balance when pushed or yanked, without any source of vision.<\/span><\/p>\n

The 90-pound, \u201cblind\u201d robot could eventually conduct power plant inspections, trek its way through sewer systems, save people in building fires, and improve mobility for the elderly population. <\/span><\/p>\n

Instead of relying on cameras, the mechanical cat uses \u201cblind locomotion\u201d to feel its way through its surroundings. <\/span><\/p>\n

\u201cBlind locomotion technology makes the robot much more robust against unexpected situations such as stepping on obstacles or collisions with un-modeled objects,\u201d said <\/span>Sangbae Kim<\/span><\/a>, an associate professor of mechanical engineering at MIT and designer of the robot. <\/span><\/p>\n

\u201cVision can be noisy, slightly inaccurate, and sometimes not available, and if you rely too much on vision, your robot has to be very accurate in position and eventually will be slow,\u201d he said in a statement. \u201cSo we want the robot to rely more on tactile information. That way, it can handle unexpected obstacles while moving fast.\u201d<\/span><\/p>\n

Compared to the Cheetah 2, this new robot has improved software and an expanded range of motion. <\/span><\/p>\n

It can stretch forwards and backwards and twist from side to side, making it nimble and athletic like a big cat. <\/span><\/p>\n

Advanced algorithms<\/b><\/h2>\n

Until this point, the researchers at the <\/span>MIT Biomimetic Robotics Lab<\/span><\/a> had not developed a machine with effective mobility on rough terrain. <\/span><\/p>\n

Two new algorithms — a contact detection algorithm and a model-predictive control algorithm — give the Cheetah 3 the power to quickly recover its balance, trek through difficult terrain, travel up staircases, and move with the near efficiency of an animal. <\/span><\/p>\n

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Image: Courtesy of the researchers<\/figcaption><\/figure>\n

The contact detection algorithm enables the robot to understand when it should stop a certain leg from swinging and place it on the ground. <\/span><\/p>\n

This algorithm keeps the robot from losing its balance because it knows whether to carry through with a step or pull back its leg when encountering an obstacle. <\/span><\/p>\n

In order for the robot to know when to transition legs, it constantly considers three probabilities — that of a leg touching the ground, the generated force from the leg hitting the ground, and if the leg will be in mid-swing. <\/span><\/p>\n

The algorithm calculates the probabilities based on data from accelerometers, gyroscopes, and the angle and height of each leg with respect to the ground. <\/span><\/p>\n

The robot\u2019s body can react to unexpected obstacles. If it steps on something, its body and legs adjust so it can keep its balance. <\/span><\/p>\n

\u201cIf humans close our eyes and make a step, we have a mental model for where the ground might be, and can prepare for it. But we also rely on the feel of touch of the ground,\u201d Kim said in a statement. \u201cWe are sort of doing the same thing by combining multiple [sources of] information to determine the transition time.\u201d<\/span><\/p>\n

The model-predictive control algorithm determines how much force the robot should apply to each leg with each step so it can move its body in the most effective way. <\/span><\/p>\n

More specifically, the algorithm works by looking a half-second into the future to calculate the proper position of robot\u2019s body and legs. <\/span>
\n<\/span><\/p>\n

\u201cSay someone kicks the robot sideways,\u201d Kim said in a statement. \u201cWhen the foot is already on the ground, the algorithm decides, \u2018How should I specify the forces on the foot? Because I have an undesirable velocity on the left, so I want to apply a force in the opposite direction to kill that velocity. If I apply 100 newtons in this opposite direction, what will happen a half second later?\u2019\u202f\u201d<\/span><\/p>\n

The algorithm makes these calculations 20 times per second.  <\/span><\/p>\n

To test it, the researchers shoved, pulled and yanked the robot as it walked on a treadmill. <\/span><\/p>\n