I saw that there are different types of accelerometers such as mechanical, piezoelectric, capacitive, semiconductor.
which one are used in robots or drones? semiconductor? obviously not mechanical. then what are the uses of piezoelectric or capacitive accelerometers?
Majority use Invensense (now TDK) mems gyro/acc
Very common one is MPU-6000, its good up to 8KHz update rate, but for 32KHz we use IMU-20602 (and 20601). I prefer 32K for lowest latency for this type of flying.