HISTORICAL DRAWING · 1970

X–Y position indicator

What surface displacement corresponds to one wheel-encoder count?

D. C. Engelbart, US 3,541,541 "X-Y Position Indicator for a Display System", sheet 1 (the mouse)
D. C. Engelbart, US 3,541,541 "X-Y Position Indicator for a Display System", sheet 1 (the mouse). View the original source and attribution ↗

A contemporary sketch model

Every number below is a modern illustrative assumption. The historical drawing supplies a question; the source model is an exercise in reasoning about it.

wheelDiameter = 20 mm in 10..30 "Illustrative rolling wheel diameter"
counts = 100 "Assumed counts per revolution"
stepSize := pi*wheelDiameter/counts [mm]
circumference := pi*wheelDiameter [mm]
check resolution: stepSize <= 1 mm
probe resolutionValue: stepSize [mm]
sweep Wheel: wheelDiameter = 10, 20, 30 mm

Model limits

Ideal no-slip wheel kinematics; no friction/contact solve, direction-decoding electronics or usability prediction.

Explore it with your agent

Create a Study, inspect the installed capabilities, and use this source as a starting point. Ask the agent to explain the equations and assumptions, then replace illustrative inputs with measured evidence for your own design.

This example includes a scalar sweep. Use napkin_sketch to add the model and napkin_run to inspect the sweep; the source editor’s scalar comparison view is for simple scenarios.

Connect your agent ↗