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W04. Control 02

Last time, we talked about telemetry and localization. As you will find out in the labs, it's often hard to do localization with just the on-board sensors. It's still hard with external sensors, but they can give you another piece of the picture.

Today, we will look at the long-range distance sensor for this course, the ultrasonic distance sensor. Eventually, we will learn to reconcile the two different sensors (encoder and ultrasonic) through a process called sensor integration, but not today. Instead, we will just get used to the ultrasonic and the signal processing issues that come up with that sensor. -->

Pre-readings and Videos​

These videos will help you understand the dynamics of ultrasound by looking at the physics of wave propogation, the functionality of the specific ultrasonic sensor you're using, and applications of sonar and ultrasound tecnhology. Practically, the McWhorter video will give you the most direct utility for your robot, but the others are very helpful when thinking through how it works and could be applied.

Understanding Waves​

Having a basic background in wave propogation is helpful to think through the physics behind an ultrasonic sensor.

Understanding and Connecting the HC-SR04 Ultrasonic Distance sensor​

Another classic McWhorter video on the distance sensor. It will give you the practical understanding of how to wire and use the sensor.

How Sonar Works​

This video explains how sonar works in some detail. Although the ultrasonic does have different properties due to the frequency range it works in, it is essentially a sonar technology that we're using.

How Ultrasound Imaging Works​

This video briefly explains how ultrasound imaging works. Although the ultrasonic sensors we're using have a different configuration and use case, the underlying mechanism is the same. Understanding the many different applications of ultrasonic waves can help us understand our specific use case of distance sensing.

Summary of the Day​

Learning Goals​

  1. Learn how to wire and program an ultrasonic distance sensor.
  2. Use ultrasonic distance sensors as a model for reasoning through any long-range sensing problem.
  3. Describe the basic problem of noisy signals and apply simple signal processing approaches such as threshold filters.