Data Sheet

Page 3

Web: www.maxbotix.com

PD11721m

MaxBotix

Inc.

Patent 7,679,996

HRLV-MaxSonar

- EZ

™

Series

MaxBotix Inc., products are engineered and assembled in the USA

Auto Calibration

Each time the HRLV-MaxSonar-EZ takes a range reading, it calibrates itself. The sensor then uses this data to range

objects. If the temperature, humidity, or applied voltage changes during sensor operation; the sensor will continue to

function normally over the rated temperature range while applying compensation for changes caused by temperature and

voltage.

Sensor Operation: Free-Run

When operating in free run mode, the HRLV-MaxSonar-EZ sensors are designed to be used in a variety of indoor

environments. Most range readings are accurately reported. If the range readings are affected, the effect is typically less

than 5 mm. This allows users to employ real-time ultrasonic distance sensing without the need for additional supporting

circuitry or complicated user software.

Many acoustic noise sources will have little to no effect on the reported range of the HRLV-MaxSonar-EZ sensors.

However, users are encouraged to test sensor operation in the operating environment.

Sensor Minimum Distance

The sensor minimum reported distance is 30-cm (11.8 inches). However, the HRLV-MaxSonar-EZ will range and report

targets to within 1-mm of the front sensor face. Large targets closer than 30-cm will typically range as 300-mm.

Sensor Operation from 30-cm to 50-cm

Because of acoustic phase effects in the near field, objects between 30-cm and 50-cm may experience acoustic phase

cancellation of the returning waveform resulting in inaccuracies of up to 5-mm. These effects become less prevalent as the

target distance increases, and has not been observed past 50-cm. For this reason, industrial users that require the highest

sensor accuracy are encouraged to mount the HRLV-MaxSonar-EZ from objects that are farther than 50-cm.

Range “0” Location

The HRLV-MaxSonar-EZ reports the range to distant targets starting from the back of the sensor PCB as shown in the

diagram below.

In general, the HRLV-MaxSonar-EZ will report the range to the leading edge of the closest detectable object. Target

detection has been characterized in the sensor beam patterns.

Target Size Compensation

Most low cost ultrasonic rangefinders will report the range to smaller size targets as farther than the actual distance. In

addition, they may also report the range to larger size targets as closer than the actual distance.

The HRLV-MaxSonar-EZ sensor line correctly compensates for target size differences. This means that, provided an

object is large enough to be detected, the sensor will report the same distance, typically within 2%, regardless of target

size. Smaller targets can have additional detection noise that may limit this feature. In addition, targets with small or

rounded surfaces may have an apparent distance that is slightly farther, where the distance reported may be a composite of

the sensed object(s). Compensation for target size is applied to all range outputs: pulse width, analog voltage, and serial

RS232 or TTL.