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Calibration Range Recorder

Run the Calibration Range Recorder MicroSim Fullscreen

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Description

Set the raw position of one joint at its middle pose and at the two ends of its sweep, and see the homing offset, the recorded range and its width in degrees. Then predict the result of a calibration run in six situations. Used in Chapter 8.

The dial shows the raw positions of one servo joint, from 0 to 4095. The orange arm is the middle pose, which sets the homing offset. The blue arc is the sweep, which sets the two range limits. The rules are the ones in the Chapter 8 section "The Calibration Procedure".

The six situations and the 40-step slip are illustrative: they were written for this MicroSim. The starting positions (2105, 800 and 3300) are the made-up positions used in the chapter's lab.

Lesson Plan

Grade level: Middle school and up (age 12+). Time: 10 to 15 minutes.

  1. Explore. Move the middle pose slider and watch the homing offset. Then move one sweep end and watch the range. Which numbers follow the middle pose, and which follow the ends?
  2. Check the arithmetic. With the starting values, work out the offset (2105 − 2047), the range and the width in degrees on paper, then compare.
  3. Make the error. Set both sweep ends to the same number. What does the program do, and why?
  4. Six situations. Switch to Six situations. Read what the builder did, then choose the result by its letter. You get one try for each.
  5. Think about it. The calibrated range is the range you moved the joint through, not the range the servo can turn. Why does that matter when you sweep each joint?

Specification

The learning objective, evidence of mastery and content for this MicroSim are specified in Chapter 8: Building and Calibrating the SO-ARM100.