Sensors for industrial mobile Robots Incremental sensors Need more/better pictures

Magnetic encoders More reliable Less expensive Less accurate than optical Less resolution (BUT can be used interpolators)

Magnetic encoders To sense direction

Interpolation to multiply resolution A considerably higher resolution of angle φ is possible if we apply the interpolation process described in Figure. The graphic representation of sin(φ) versus cos(φ) produces a circle as a special Lissajous figure in which angle φ is immediately recognizable. The interpolator now compares the current angle value φ0  with predefined discrete angle positions and as a result generates the matching quadrature signals A and B.

A complete scheme with interpolator

Gyroscope – fiber optic

Gyroscope vibrating Coriolis force:

Example: Use of encoders + gyro Steering encoder gyro Traction encoder … my first AGV prototype

The discrete form of the inertial-odometric navigation equations is as follows: Use of encoders + gyro

Use of encoders + gyro

We have two separate estimations of the attitude so we have to combine them in a suitable (possibly optimum) way. To achieve this the two attitude increments are combined by a data-fusion algorithm in order to estimate the best guess for the two. The procedure is as follows: the two increments are estimated, the type of manoeuvre the vehicle is actually undergoing is estimated using the inertial-odometric data (table 2), the accuracy ratio of the output of the two navigation systems is estimated using table 1 the data fusion algorithm combines the two increments the output of the data-fusion algorithm is added to δk Use of encoders + gyro

Step 1 – attitude increments est.

Step 2 – manoeuvre estimation

Bayes Fusion (optimum in case of Gaussian white noise) Step 3 – data fusion

Step 4 – accuracy ratio estimation the accuracy ratio of the output of the two navigation systems is estimated using table 1 Step 4 – accuracy ratio estimation

Step 5 – add the increment the output of the data-fusion algorithm is added to δk: Step 5 – add the increment