define AI: AI is making the computers do stuff normally assoicated with human intelligence, like perceiving and reasoning. for a free simple course on ai, check out this course

3 sub-fields of AI: machine learning, computer vision, robotics

why is AI booming now availabilty of huge data set, affordable parallel computer, and better algorithms.

3 fields where robotics are widely employed and why manfucatiuring, because of its repetitive nature and importance on precision. warehousing, e-commerece growth required such technology, healthcare, surgical precision and disinfection that reduces staff exposure to risk, you can read more about the usage of robots here

3 challenges of a robot performing a 24h surveillance task in a large facility: moving between crowds, energy and uptime that can power round the clock operation, reliable preception and trust that is able to detect real anomalies at night and in changing lights, there is an interesting study on this, u can find it here