Many robots are anthropomorphic—they look, act, or seem like humans. Scientists and engineers often design robots to look like humans or other animals. Building machines to operate autonomously is a daunting task, so researchers start with animals and people as models because they are examples of working mechanisms.

The first robot manipulator was built to look and function like an arm. The first mobile robot had a human-like "head." Most legged robots walk with gaits copied from mammals, insects, or lizards. Many sensors are designed to use the same information that humans use: cameras and computer vision allow the robot to "see"; whiskers and contact switches allow the robot to "feel"; and researchers are even working on electronic devices that will allow robots to "smell."

However, robots do not have to be anthropomorphic. Since engineers design robots from scratch...