Boston Dynamics is a fascinating company best known for periodically releasing videos of robot prototypes of all shapes and sizes. The robots are always impressively engineered, and sometimes a little creepy. The creepiness is not by design; it’s an unintended side effect of robots that imitate human and animal movements. This makes them seem familiar and alien at the same time — half-biological and half-machine.

The robot maker is a subsidiary of search giant Google, but the company began in 1992 as a spinoff from the Massachusetts Institute of Technology (MIT), allowing robotics experts to continue their work on animal-like robots outside of academia. Their goal is not only to create innovative machines, but also to have them work outside of a lab, which is why in many videos you’ll see robots facing harsh conditions that would defeat most other robots, including being pushed and kicked by Boston Dynamics employees!

Below is a brief introduction to the Boston Dynamics (BD) family of robots. In a few years, you might meet them in the real world.

BigDog

One of the most famous BD robots, BigDog is a dynamically stable quadruped created in 2005 with help from Foster-Miller, NASA’s Jet Propulsion Lab (JPL) and Harvard’s Concord Field Station. The project was funded by the Defense Advanced Research Projects Agency (DARPA) because the military was looking for a robotic pack mule that could help soldiers carry equipment and supplies over terrain too difficult for other vehicles to handle, including mud and snow.

That’s why BigDog has four legs instead of wheels or tracks. A variety of sensors, including a laser gyroscope and a stereo vision system, help it navigate difficult and uneven paths. It’s 3 feet long, 2.5 feet tall, weighs 240 pounds and can carry 340 pounds at 4 miles per hour on rough terrain, up to a 35 degree incline. A modified version has an arm and can throw heavy cinder blocks a surprising distance.

The BigDog project was discontinued in late 2015 because the two-stroke, one-cylinder gasoline engine on board was deemed too noisy for use by the military in combat situations. For more details on BigDog, check out the detailed overview (pdf) from Boston Dynamics.

Cheetah

Cheetah is all about speed, like its living namesake. It holds a speed record for legged robots of over 29 miles per hour, beating a 1989 record of 13.1 miles per hour set at MIT and even beating Usain Bolt’s 20-meter split at the 2012 Olympics.

The version of Cheetah in the video above runs on a treadmill in the lab and is tethered. A free-running version called Wildcat began testing in 2013.

LittleDog

LittleDog is different from most other BD robots. It was built by BD, but it was intended as a platform that others could use for software testing. For example, the LittleDog robot in the video above was programmed by the Computational Learning and Motor Control Lab at the University of Southern California.

Each of LittleDog’s four legs are powered by three electric motors, giving it a wide range of motions. This is to better study various aspects of locomotion on all kinds of terrain. The onboard lithium-polymer batteries give it 30 minutes of continuous operation without the need for recharging.

RiSE

RiSE is an insect-like robot that's all about climbing vertical surfaces. Using six legs powered by two electric motors and micro-claws, it can scale walls, trees and fences — even telephone poles.

Boston Dynamics developed RiSE in collaboration with the University of Pennsylvania, Carnegie Mellon, UC Berkeley, Stanford, and Lewis and Clark University. It was funded by DARPA.

SandFlea

SandFlea is less animal- or human-looking than what Boston Dynamics usually creates, but its behavior is definitely reminiscent of the humble flea, just on a much larger scale. Fleas are only 1/8 or 1/16th of an inch long, yet they can jump vertically up to 7 inches and horizontally up to 13 inches, making them one of the best jumpers relative to body size.

As you can see in the video above, SandFlea can jump up to 30 feet in the air, allowing it to bypass obstacles that would be impossible for it to roll over, and it can even jump on the roof of a buildings. Not bad for a robot about the size of a phone book!

PETMAN

PETMAN is one of BD’s human-like robots. The name stands for Protection Ensemble Test Mannequin.

In the video above, it might look like a person wearing a biohazard suit walking with a stilted gait, but it’s a robot that was designed for the U.S. Department of Defense to test chemical protection suits. The goal is to make testing as realistic as possible, so PETMAN can do a wide variety of motions to stress test the suits, and it simulates human physiology by controlling temperature, humidity and even by sweating (which is a little creepy).

LS3

The name LS3 stands for Legged Squad Support System. It’s a robot descended from BigDog that was made more rugged for military use in hot, cold, wet and dirty environments. It can carry 400 pounds of equipment and supplies and enough fuel for a 20-mile mission lasting a whole day.

LS3 can be set to automatically follow someone or to go to a certain location using GPS coordinates. LS3 was funded by DARPA and the U.S. Marine Corps.

Atlas

Boston Dynamics recently released the video above showing the latest version of Atlas, a bipedal humanoid robot about 6 feet tall, weighing around 180 pounds, and designed to operate indoors and outdoors.

It’s designed to assist emergency responders in search-and-rescue operations, performing tasks such as shutting off valves, opening doors and operating powered equipment in environments where humans cannot survive. The U.S. Department of Defense, which provides funding for Atlas, said that it had no interest in using it for offensive or defensive tasks.

The video above is particularly interesting because it shows how Atlas interacts with the world when things go wrong. At one point it’s trying to grab a box that is being moved around by someone with a hockey stick, and at another it’s being forcefully pushed flat to the ground and has to get back up by itself. Most robots aren’t this resilient when things don’t go as planned.

RHex

RHex is designed for rough terrain. Thanks to its six curved limbs, it can move on almost any type of surface and can keep going even if it has been turned upside down. It runs four hours on a battery charge and sends back high-resolution video of what it sees. The robot’s body is sealed, so it’s not afraid of water and mud. The human operator can control it from a distance of up to 700 meters.

Spot

Finally, we have Spot, a dog-like four-legged robot for indoor and outdoor use. As you can see in the video, Spot is stable enough to keep going even after being pushed hard by someone, and it can handle all kinds of terrain, even stairs and grassy hills. Spot weighs around 160 pounds, and is battery-powered, so it’s much quieter than its larger cousin, BigDog.

The four-legged robot is electrically powered and hydraulically actuated. Spot has a sensor head that helps it negotiate rough terrain.

This video by Steve Jurvetson, a venture capitalist who’s on the board of Tesla Motors and SpaceX, shows Spot meeting a real dog. Looks like Fido’s not so welcoming of his new robotic acquaintance.

Michael Graham Richard ( @Michael_GR ) Michael writes for MNN and TreeHugger about science, space and technology and more.