Nomad uses a laser range finder to measure the distance to objects and a metal detector to help determine the composition of the objects if finds. Very complex robots like Cassini have full sets of sensing equipment much like human senses. It's skeleton must be light and sturdy, able to withstand extreme temperatures and monitor those temperatures. Cassini determines it's location by using three hemisperical resonant gyroscopes or HRG's which measures quartz crystal vibrations. As working machines, robots have defined job duties and carry all the tools they need to accomplish their tasks onboard their bodies.
Many robots carry their tools at the end of a manipulator.
The manipulator contains a series of segments, jointed or sliding relative to one another for the purpose of moving objects. The manipulator includes the arm, wrist and end-effector. An end-effector is a tool or gripping mechanism attached to the end of a robot arm to accomplish some task. It often encompasses a motor or a driven mechanical device. An end-effector can be a sensor, a gripping device, a paint gun, a drill, an arc welding device, etc.