Common grippers include fingered and vacuum types. Another central element of robotics control technology is the sensor. It is through sensors that a robotic system receives knowledge of its environment, to which subsequent actions of the robot can be adjusted.
Sensors are used to enable a robot to adjust to variations in the position of objects to be picked up, to inspect objects, and to monitor proper operation (although some robots are able to adjust to variations in object placement without the use of sensors, provided they have sufficient end effector flexibility).