CS452 - Real-Time Programming - Spring 2009

Lecture 24 - Calibration

Controlling a Train

Types of Control

Ballistic Control

Feedback Control


The sensors give us large granularity feedback control.

Between the sensors we must use ballistic control,


Based on


Measuring Speed

The easy part

Collect many such measurements

Using a Calibration

The other easy part

  1. Arrive at sensor N at time t
  2. Look up velocity to use in calibration table
  3. Position at time t' is sensor position + velocity x (t' - t)

Building a Calibration Table

The hard part.

Two things are hard.

  1. Dealing with measurement error
  2. Determining what state is relevant

    State is has many potentially relevant aspects

Practical Issues

  1. You are already doing a whole lot of measurements
  2. Average in a circular buffer
  3. Size & align table by size & alignment of cache lines

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