An animal robot is a robot inspired by an animal, or that looks like an animal. Actually, these are 2 very different categories:
1- some wall-climbing robots use a technology inspired by how geickos stick to wall, but don't look at all like a geicko. On the other side, you have some snake looking robots that move on wheels.
2- Let's explore more of the first category: how can you use the design from nature to create your robots? Let's start with the example of the snake robot, since they happen to mostly look like snakes too. Then I'll show you a mix of other robots that are really cool too.
Why snake robots anyway? Well, snakes can move in wild variety of conditions without using legs. They can go through very narrow pipes, climb very steep slopes, and use yet other techniques to go on sand, or on soapy floors, etc. They can even swim and climb trees. That's for adaptability.
So, scientists who are trying to create an animal robot want to reach as much adaptability as possible. Here are 2 robots inspired by snake: one (on the right) looks like a snake and is amphibious (that's already cool), and the other one (below) is trying to use a very safe and energy-efficient method of climbing very steep slopes, but doesn't look like a snake robot at all.
Snake robot by Prof. Hirose in Japan
Doesn't look like a snake, but moves like one. More info here
Now, these are already quite cool. But take a team of crazy heavy metal artists (I don't mean the music, I mean literally), and give them enough money for the parts (I heard the Kickstarter website was useful there), and see the results.
Of course, there are not only snake robots in the wild. You can find robotics bugs in almost every home: did you know the Roomba was inspired by ants and other small bugs?
You can also find some robot fish. While some are ultra realistic, others are designed for the entertainment. Like the Jessiko robot fish, created to swim in shoals and lighted up with LEDs for a beautiful spectacle.
They can swim along with real fishes
'What else?' you say. Many people have tried to create robots that can climb vertical walls. It's not a problem for geickos, and some laboratories have managed to create geicko like materials that stick on anything just like the animal legs.
Another robot, though not so much of animal robot, was inspired by lizards that use their tails for keeping balance in jumps. The actual robot is a little car with motorized tails, but they showed it could actually be used to control the momentum during the fall (which means they can make the robot turn in the air to land on its wheels). It's the same principle for cats too.
Other pages that may interest you:
The Jessiko robot fish. Discover the Jessiko Robot fish through an interview with its creator Christophe Tiraby.
BigDog robot. This is the most advanced legged robot, and I explain all it's awesome features here.
The dog robot pets. You wish your animal robot was a great dog pet? Look for these 2 awesome robots with advanced AI.