Ultrasonic Sensor

Measure distance from object in centimeters

Library

Simulink® Support Package for LEGO® MINDSTORMS® EV3 Hardware

Description

Measure the distance between the EV3 Ultrasonic Sensor and the nearest object in front of the sensor.

The sensor can detect objects from approximately 5 to 255 centimeters away.

When the nearest object is beyond the maximum range of the Ultrasonic Sensor, the sensor outputs the maximum value, 255.

The measured distances are approximate. For greater precision, calibrate the sensor output values against physical measurements.

The distance from which the sensor first detects an approaching object depends on:

  • The ultrasonic reflectance of the object, which is a function of the object’s size and composition. The sensor detects large hard objects from a greater distance than small soft ones. For example, the sensor might detect a pane of glass at 255 cm and a hand puppet at 150 cm.

  • The angle of incidence of the object relative to the sensor. The sensor detects objects directly in front of it at greater distances than objects off to the sides.

The block output emits values as uint8.

During simulations without hardware, this block emits zeros. See Block Produces Zeros or Does Nothing in Simulation (Simulink).

Parameters

EV3 brick input port

Select the EV3 sensor port to which the sensor is connected. Avoid assigning multiple devices to the same port. The options are 1, 2, 3, or 4.

Sample time

Specify how often the block reads sensor values. This value defaults to 0.1. Shorter sample times, such as 0.01, may produce unreliable measurements.

Smaller values require the processor to complete the same number of instructions in less time, which can cause task overruns.

See Also