Sensors

[theawesome1730]

Gyroscope:
Always, always, always use a gyroscope on your robot for autonomous, you would not believe how much better it is when you have to drive in a straight line. Be warned, when you place your robot, it must be off and once you turn it on, you cannot move it or the gyro will be calibrated wrong.

Accelerometer:
Useful for things this year like balancing the bridge, it determines angle so you can tell if the bridge is level or not.

Shaft Encoders:
Lots of different types, there are optical, magnetic etc. (more, but I can't think of any). Put these on your drive train, shooters that use wheels, anything that spins freely like wheels. they don't have physical limits and therefor cannot be broken by spinning too far. use these to judge speed of drivetrain, Set up PID loops in your code to tell shooter wheels to run at a set speed (you can control speed based on RPMs rather than voltage, it's much more accurate) These work well for high speed, but also work with slower speeds too.

Potentiometers and string-pots
Have physical limits! Cannot be used for wheels or shooters as they cannot fully rotate forever. Good for arms and turrets, could also be used with crab or swerve drive (to some degree) You can measure rotational distance and angles.

Light sensors:
Use them to track lines like in 2011

Sonar/Ultrasonic:
Determine distance from objects/other robots/field walls

Lasers and Sensor: same uses as above

Camera: Vision tracking, line following, goal finding, game piece finding etc.

Kinect: Same as camera + sonar/ultrasonic and laser.

Limit switches: determine limits rotationally (turrets or arms) or linearly (slides, elevators, pneumatic cylinders etc.) You can also use them to detect game pieces.

All I can think of right now, sorry if I missed any big ones, but thats what I know.

Edit: Get a variety of the same type of sensor, some work better in other locations than others and get a variety of sensors as well.