IMU 1

MicroElectroMechanical Systems (MEMS) Inertial Measurement Unit (IMU)

Attitude relative to gravity vector

Magnetic heading Rotational velocity Translational acceleration

IMU 2

Absolute rotational attitude of object

Direct measurement of angular velocity

Direct measurement of translational acceleration

Positives

IMU 3

Does not provide – absolute location translational velocity rotational acceleration

Data communication Medium resolution < 150 Hz

Negatives

IMU 4

Vehicle navigation Intercontinental ballistic missiles (ICBM) Nuclear submarines Cruise missiles

MEMS Automotive Consumer products

History of IMUs

IMU 5

Automotive Accelerometers to deploy airbags Vehicle roll handling

MEMS IMUs - Automotive

IMU 6

Games (WiiMote) PDA (iPhone) Camera

stabilization Hard disks

MEMS IMUs – Consumer Products

IMU 7

MEMS Fabrication

IMU 8

acceleration

gravity

MEMS accelerometer(proof mass)

IMU 9

MEMS Comb Sensor/Drive

IMU 10

MEMS Differential Capacitance

IMU 11

MEMS Differential Capacitance

IMU 12

MEMS accelerometer

IMU 13

MEMS gyro (torsion)

IMU 14

MEMS gyro (planar)

IMU 15

MEMS magnetometer (magnetoresistive)

IMU 16

Signal Analog voltage (0 to 3V) Fixed frequency, variable duty cycle Digital (internal A/D converter)

Nominal Bandwidth 550 Hz for accelerometer 150 Hz for gyro 50 Hz for magnetometer

MEMS IMU Outputs

IMU 17

Biaxial accelerometer Uniaxial gyro

Two-Dimensional (2D) IMU

IMU 18

Triaxial accelerometer Triaxial gyro Triaxial magnetometer

Required to determine spin about gravity vector

Three-Dimensional (3D) IMU

ax

ayaz

IMU 19

Triaxial accelerometer ±3g, 300 mV/g, 550 Hz

Triaxial gyro ±300 deg/sec (dps), 3.3mV/dps, 140 Hz

Triaxial magnetometer 50 Hz

On-board CPU, serial I/O

9DOF Board – Sparkfun

MEMS IMU 20

Triaxial accelerometer ±2g, ±4g, ±8g and ±16g

Triaxial gyro ±250, ±500, ±1000, and ±2000dps

Triaxial compass On-board motion fusion, I2C serial

9DOF Chip – Invensense MPU-9150