The role of a human arm is to move the hand to different positions. Similarly, the role of a robot arm is to move an end-effector. You can attach various types of end-effector to a robot arm for specific application scenarios. One common type of unterminal actuator that grips and moves different items is a simplified version of a human hand.
Robotic arms often have built-in pressure sensors that are used to tell the computer how hard the robot is gripping a particular object. This keeps the object in the robot's hand from falling or being crushed. Other unterminated actuators include blowtorches, drills, and paint sprayers.
Industrial robots are specialized to perform the exact same job over and over again in a controlled environment. For example, a particular robot might be responsible for screwing lids on jars of peanut butter that are being transported on an assembly line. To teach the robot how to do this job, a programmer would use a handheld controller to guide the robotic arm through the entire set of actions. The robot stores the exact sequence of motions in memory and thereafter does the set of motions over and over again whenever a new jar is transferred on the assembly line.
Most industrial robots work on automobile assembly lines, where they are responsible for assembling cars. When doing a lot of this kind of work, robots are much more efficient than humans because they are very precise. No matter how many hours they've been working, they can still drill holes in the same places and screw nails with the same amount of force, and manufacturing robots also play an important role in the computer industry, where their incredibly precise hands can assemble a tiny microchip.
Robotic arms are relatively easy to build and program because they work in a limited area. If you're sending a robot out into the big wide world, things get a little more complicated.
The first challenge is to provide a workable locomotion system for the robot. If the robot only needs to move on flat ground, wheels or tracks are often the best choice. If the wheels and tracks are wide enough, they are also suitable for more rugged terrain. But robot designers often want to use legged structures because they are more adaptable. Building robots with legs also helps to inform researchers about natural kinematics, a useful practice in the field of biological research.
The legs of a robot are usually driven back and forth by hydraulic or pneumatic pistons. The individual pistons are attached to different leg parts, like muscles attached to different bones. Getting all these pistons to work together in the right way is a challenge; in infancy, the human brain has to figure out which muscles need to contract at the same time in order to walk upright without falling over. Similarly, the designer of a robot must figure out the correct combination of piston movements associated with walking and program this information into the robot's computer. Many mobile robots have a built-in balancing system (Such as a set of gyroscopes) that tells the computer when the robot's movements need to be corrected.