---
title: Measuring Wheel Speed
summary: Convert encoder counts over time into rotational speed for a drive wheel.
chapter: Using Encoder Feedback
order: 1
tags:
  - speed
  - odometry
  - robotics
estimated_minutes: 9
---

# Measuring Wheel Speed

Position counts become useful control signals once you add time.

To estimate wheel speed:

1. sample the encoder count at a fixed interval
2. subtract the previous count from the current count
3. divide by the sample period
4. convert counts per second into revolutions per second or wheel surface speed

## Why this matters

Speed feedback is the bridge between open-loop motor commands and predictable robot motion.

If two drive motors get the same PWM value but spin at different speeds, your robot will drift. Encoder-based speed estimation lets you detect and correct that mismatch.

## Checkpoint

Plot wheel speed over time while ramping the motor command up and down.