intro to inertial elecia white logical elegance, inc. embedded.fm @logicalelegance
TRANSCRIPT
Plans
60%: Accelerometer, gyro, magnetometer
30% Navigation is hard 15% Kalman filters, quaternions are
awesome 10% Calibration is expensive 8% Summary of sensors,
applications, costs
Sensors
Accelerometers measure gravity
Gyros Angular rate sensors measure spinniness
Magnetometers measure north and magnets
Look! Pretty lights!
Accelerometers measure gravity (apples)
Gyros Angular rate sensors measure spinniness (gestures)
Magnetometers measure north and magnets (compass)
Acronymic Combinations
A+G = Vertical gyro, A+M = Tilt compensated compass A+G+M = Attitude heading reference (AHRS) A+G+M+GPS = Fusion navigation solution
IMU, IMU with nav library 9DOF – accel + gyro + mag 10DOF – barometric and/or temperature
Barometric is for altitude but only good for relative measurements
Cost comparison
Prices change pretty rapidly Not recommendations, not exact
Sensor Specific Price Board
Price (1kq)
Accel MMA8451ADXL345
$8 (Adafruit)$18
$1.20$4.70
Gyro(Rate)
L3GD20HMAX21000
$13 $3.18$2.92
Mag HMC5883LMAG3110
$10$15
$1.55$0.78
IMU L3GD20H+LM303LSM9DS0 MPU-9150**
$20$20$35
$3.18 + 1.76 $5.32$7.12
Links and books
Embedded.fm episodes: 9 (Kidnapped and
Blindfolded) 43 (A Lot of High-Falutin’
Math) Adafruit 9DOF code (
github) Hackaday.io/elecia for
North Star IMU light example