Last night I was watching the matrix movies, got to thinking of how one would build a sentinel (disturbing picture attached), here are the general obstacles:

1. Autonomous mobility, both flying and walking
2. Able to "see" and "hear" much much better than humans
3. Wireless communication with central control, to receive updated instructions
4. Weapons, mainly a high density laser able to cut through metal, or sharp tentacles to cut through human tissue
5. Self termination, able to use its energy to power another machine and in the process "kill" itself
6. Able to become part of a swarm and thus act as a member of a group
7. Susceptible to EMP
8. Able to have a primary objective; search and destroy or just explode, but which can change at any time on instructions from main control
9. Able to come up with a strategy based on real life scenario, e.g. best method of attack
10. Easy to mass produce

So, what technology is missing to build one?

1. Autonomous mobility, both flying and walking - borrow from aircraft autopilot, HRP-4C,
2. Able to "see" and "hear" much much better than humans
3. Wireless communication with central control, to receive updated instructions - borrow from mars rover
4. Weapons, mainly a high density laser able to cut through metal, or sharp tentacles to cut through human tissue - armed robots guarding korean borders?
5. Self termination, able to use its energy to power another machine and in the process "kill" itself
6. Able to become part of a swarm and thus act as a member of a group
7. Susceptible to EMP
8. Able to have a primary objective; search and destroy or just explode, but which can change at any time on instructions from main control
9. Able to come up with a strategy based on real life scenario, e.g. best method of attack - DARPA Grand Challenge?
10. Easy to mass produce - Japan?