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Sensing rotation, the IMU

Sensing rotation, the IMU

1.[2p]

A gyroscope is trusted for the fast part of attitude sensing because

Correct
The answer is: it reports rotation rate immediately, with little delay or sensitivity to vibration
The answer is: it reports rotation rate immediately, with little delay or sensitivity to vibration
The answer is: it reports rotation rate immediately, with little delay or sensitivity to vibration

2.[2p]

An uncalibrated gyroscope has a bias of 0.3 degrees per second. If its rate is integrated to estimate angle while the craft sits still, how many degrees of error accumulate after 120 seconds?

CorrectNot quite: 36

3.[2p]

An accelerometer can estimate tilt without drift because

Correct
The answer is: it reads the fixed direction of gravity directly, needing no integration
The answer is: it reads the fixed direction of gravity directly, needing no integration
The answer is: it reads the fixed direction of gravity directly, needing no integration

4.[2p]

The accelerometer is unreliable for tilt during flight because

Correct
The answer is: it cannot separate gravity from the craft's own vibration and acceleration
The answer is: it cannot separate gravity from the craft's own vibration and acceleration
The answer is: it cannot separate gravity from the craft's own vibration and acceleration

5.[1p]

A flight controller asks to sit still and level at power-up so it can measure and subtract each sensor's resting bias.

Correct
The answer is: True

6.[2p]

Filtering the raw IMU signals is a compromise because

Correct
The answer is: more smoothing removes noise but adds delay, and delay in a fast control loop causes trouble
The answer is: more smoothing removes noise but adds delay, and delay in a fast control loop causes trouble
The answer is: more smoothing removes noise but adds delay, and delay in a fast control loop causes trouble

7.[3p]

Match each sensor to its strength and its weakness.

  • Gyroscope strength

  • Gyroscope weakness

  • Accelerometer strength

  • Accelerometer weakness

  • noisy and fooled by motion in flight

  • immediate, accurate rotation rate

  • drifts when integrated to an angle

  • drift-free sense of which way is down

Show the answer

Gyroscope strength: immediate, accurate rotation rate Gyroscope weakness: drifts when integrated to an angle Accelerometer strength: drift-free sense of which way is down Accelerometer weakness: noisy and fooled by motion in flight