Ultrasonic Sensor Review: Comparing DFRobot URM09, HC-SR04, Devantech SRF02 & Maxbotix MB1040

Riding the wave of the Internet of Things and driven by maker culture, ultrasonic sensors have become a key tool in today's technology fields. These small devices, based on acoustic echo-ranging technology, play a crucial role in various industries with their non-contact measurement methods and outstanding precision. From the automation lines of industrial manufacturing to the reverse parking radar systems of automobiles and to the intrusion detection in the field of security monitoring, the applications of ultrasonic sensors are ubiquitous.

This article will delve into four mainstream series of ultrasonic sensors: URM, HC SR04, Devantech, and Maxbotix, analyzing their working principles, performance characteristics, and real-world application examples. By comparing the specifications and conducting performance tests on four specific ultrasonic sensors (URM09; HC-SR04; SRF02; EZ4 MB1040), our aim is to provide you with a comprehensive evaluation framework to help you choose the most suitable ultrasonic sensor for your specific application needs.

1. Introduction to Ultrasonic Sensors

Ultrasonic sensors are devices that utilize ultrasonic waves (sound waves with frequencies higher than the audible range for humans, typically above 20kHz) for measurement and control. They have a wide range of applications in the IoT industry because they can provide contactless, high-precision, and real-time measurements. In this section, we will introduce the basic principles and application fields of ultrasonic sensors.

1.1 Basic Principles

The working principle of ultrasonic sensors is based on the characteristics of ultrasonic wave propagation in a medium. A sensor typically consists of a transmitter and a receiver. The transmitter generates an ultrasonic signal, which then propagates through the air or another medium. When the ultrasonic waves encounter the surface of an object, they produce echoes that are captured by the receiver. By analyzing the propagation time or phase difference of the ultrasonic signal, it is possible to measure physical quantities such as the distance, speed, and direction of the object being measured.

The accuracy and measurement range of an ultrasonic sensor depend on its operating frequency and transmission power. High-frequency sensors can provide higher resolution but have a smaller measurement range; conversely, low-frequency sensors have a larger measurement range but lower resolution. Additionally, the propagation speed of ultrasonic waves in different media also affects the performance of the sensor.

Figure: Ultrasonic Sensor Working Principle

For more information on the principles of how ultrasonic waves measure speed, you can click on this article to learn more.

1.2 Application Fields

Ultrasonic sensors are widely used in the IoT industry, and here are some of the main application areas:

• Distance Measurement: Ultrasonic sensors can be used to measure the distance between objects, for example, in parking management systems to detect the distance between a vehicle and obstacles.
• Level Monitoring: Ultrasonic sensors can be used to measure the height of liquids, such as in reservoirs and oil tanks, to monitor liquid level changes in real time.
• Flow Measurement: By measuring the propagation time of ultrasonic waves in a fluid, the flow rate and volume of the fluid can be calculated, which is widely used in the flow monitoring of water, gas, and other fluids.
• Object Detection and Positioning: Ultrasonic sensors can be used to detect the presence and location of objects, for example in warehouse management and robot navigation scenarios.
• Structural Health Monitoring: Ultrasonic sensors can be used to detect cracks, corrosion, and other conditions in building structures, pipelines, and other facilities, providing early warning of potential safety hazards.

Figure: Common Application Scenarios of Ultrasonic Sensors

2. Introduction to the Four Major Ultrasonic Sensor Series

In the field of ultrasonic sensors, there are four renowned series of products: the URM series, HC-SR04, Devantech, and Maxbotix. Each of these sensor series has its own characteristics and is widely used in various industries. Below, we will introduce in detail the ultrasonic sensors from these four series.

2.1 URM

The URM series is a range of ultrasonic distance measurement modules specifically designed for the industrial control and robotics control sectors, favored by beginners and small to medium-sized projects for their high cost-performance ratio. These sensors stand out for their excellent distance measurement precision and stability, with a relatively moderate price.

Since the introduction of the first URM37 in 2009, DFRobot has successively launched 14 URM series ultrasonic distance measurement modules, covering a variety of measurement ranges (from 2 centimeters to 1000 centimeters), beam angles, precision levels, and interface options to meet diverse application needs.

These modules feature internal temperature compensation, which allows for accurate measurement of the distance between the sensor and the target object. In terms of operating voltage, URM series sensors are 5V, making them compatible with development platforms such as Arduino and Raspberry Pi. Additionally, their low power consumption and compact size make integration into various devices easy and convenient. Therefore, URM series sensors are particularly suitable for applications that require high precision, such as robot navigation, object detection, and obstacle avoidance.

Learn More: DFRobot URM Ultrasonic Distance Sensor Selection Guide

2.2 HC-SR04

The HC-SR04 ultrasonic sensor is a cost-effective sensor widely used in robotics, automation equipment, and other distance measurement scenarios. It has gained a strong position in the market due to its affordable price and impressive performance, making it particularly popular among beginners and DIY project enthusiasts.

Since its introduction, the HC-SR04 has become a classic in the field of ultrasonic distance measurement sensors. Its measuring range is between 2 centimeters and 400 centimeters, suitable for a variety of distance detection tasks. In terms of power requirements, the HC-SR04 operates on a 5V supply, making it compatible with mainstream development platforms such as Arduino and Raspberry Pi. In addition, the HC-SR04 sensor has low power consumption and a compact size, making it easy to embed in various devices. Therefore, this sensor is suitable for DIY projects and educational applications where precision measurement requirements are not extremely high, such as smart cars, object detection, and obstacle avoidance.

Figure：Ultrasonic Distance Sensor - HC-SR04

2.3 Devantech

Devantech ultrasonic sensors are a series of high-performance and high-precision sensors manufactured by the British company Devantech, renowned for their exceptional performance and stability.

The characteristics of Devantech ultrasonic sensors include high precision, a variety of interfaces, and reliability. They operate within a voltage range of 2.5V to 5.5V and have a measurement range that varies from 2 centimeters to 6 meters, offering high measurement accuracy. These sensors provide multiple interface types, such as I2C, RS232, PWM, and analog output, to meet the needs of different application scenarios.

Devantech ultrasonic sensors are suitable for a wide range of applications, such as automated equipment, drones, robot navigation, etc., providing reliable solutions for the industrial control sector, robotics control field, and various complex applications.

Figure：Ultrasonic Distance Sensor - Devantech: SRF02

2.4 Maxbotix

Maxbotix is a well-known ultrasonic sensor manufacturer from the United States, famous for the research, development, and production of high-quality ultrasonic sensors.

The Maxbotix series of ultrasonic sensors are characterized by high precision, low power consumption, and strong anti-interference capabilities. These sensors can work stably under various environmental conditions, including adverse weather, high humidity, and high temperatures. In addition, Maxbotix sensors have low power consumption, making them an ideal choice for remote monitoring and Internet of Things (IoT) applications.

The price of the Maxbotix series of ultrasonic sensors is much higher compared to similar products, but their outstanding performance, precision, and reliability make them the preferred choice for high-end industry applications and institutions, such as industrial automation, environmental monitoring, unmanned aerial vehicles (UAVs), and more. These customers usually have strict quality requirements for sensors and are therefore willing to invest at a higher price point to ensure they receive products with exceptional performance.

Figure：MaxBotix Ultrasonic Sensor

3. Performance Review of Four Ultrasonic Sensors

With numerous models of ultrasonic sensors from brands like "URM, HC-SR04, Devantech, Maxbotix," our goal is to provide a clear and objective comparison to assist in your decision-making process. We have carefully selected the most economical and popular model from each brand—URM09, HC-SR04, SRF02, EZ4 MB1040—for thorough evaluation. These selected products have all undergone our "Precision Measurement Test" and "Data Jitter Test" to ensure the reliability and practicality of the comparison results. Through our analysis, you will not only gain an in-depth understanding of each sensor's characteristics and performance but also acquire valuable insights to meet your specific needs and choose the most suitable ultrasonic sensor.

• URM: Gravity: URM09 Ultrasonic Sensor
• HC SR04: Ultrasonic Distance Sensor - HC-SR04
• Devantech: SRF02 Ultrasonic Distance Sensor (16~600cm)
• Maxbotix: LV-MaxSonar-EZ4 MB1040

3.1 Parameter Comparison and Analysis

To help you better understand the performance and characteristics of these four ultrasonic sensors, we have compared and analyzed their parameters, interfaces, price indices, and more, highlighting the advantages and disadvantages of each.

Below is the detailed parameter comparison:

Note: Beam angle diagram for Maxbotix MB1040 is provided.

The actual beam angle changes over the full range. Use the beam pattern for a specific target at any given distance to calculate the beam angle for that target at the specific distance. Generally, smaller targets are detected over a narrower beam angle and a shorter distance. Larger targets are detected over a wider beam angle and a longer range.

Figure：MB1040 Beam Pattern

Gravity: URM09

• Advantages: Supports multiple interface types, including I2C, analog, and Trig, offering flexible connection options. It has high accuracy and is compatible with various voltages, making it suitable for different embedded systems.
• Disadvantages: Compared to other models, it is slightly more expensive, and the wider beam angle may detect unnecessary objects in narrow spaces.

HC-SR04

• Advantages: Very cost-effective, widely used in educational and hobbyist projects. The narrower beam angle helps with more precise distance detection.
• Disadvantages: Single interface type (only supports GPIO), and an overly narrow beam angle might miss areas that need to be detected.

Devantech: SRF02

• Advantages: Has a wide measurement range, and the supported interface types make it well compatible with a variety of applications.
• Disadvantages: Higher price, may not be suitable for budget-sensitive projects.

Maxbotix: EZ4 MB1040

• Advantages: High precision and an extensive measurement range; multi-interface support offers high flexibility; a broad operating temperature range makes it very suitable for harsh environments and industrial settings.
• Disadvantages: The highest price, which might not be the best choice for projects with limited budgets.

3.2 Performance Testing

Since accuracy and data stability are crucial in the field of automation control and distance detection, we conducted a series of detailed performance tests on these four popular sensors—SR04, URM09, Maxbotix MB1040, and SRF02. Our goal is to evaluate and compare the performance of these sensors in terms of accuracy and data stability, to provide a reference for your subsequent product selection.

Test Environment:

• Room Temperature: 24 degrees Celsius
• Humidity: 47% RH
• The ground or other objects in the test environment may interfere with the transmission and reception of ultrasonic waves (for example, the ground may reflect ultrasound), so the sensors were elevated approximately 76cm during testing, and a flat wall surface was used for the tests. The four sensors were fixed on stands to ensure a consistent starting point for each test.

3.2.1 Precision Measurement Test

The core objective of this test is to verify the measurement accuracy of the sensors. To do this, we will conduct a series of measurements at a preset fixed distance (near distance at 50cm; mid-distance at 1m, and far distance at 3m) to monitor the consistency of each reading. These consecutive measurements will provide us with reliable information about the sensors' precision and repeatability, which is crucial to ensure that the sensors can deliver accurate measurements in real-world applications. After the sensor readings have stabilized, we will collect data at a frequency of once per second to accurately capture the performance of the sensors.

We conducted three such tests for each of the actual four products to compare and analyze the performance differences between different products and the same product in different tests.

Test Distance: Near Range 50cm

Test Distance: Mid-Range 1m

Test Distance: Long Range 3m

Based on the experimental results, we have observed the following characteristics for your reference:

• Gravity: URM09

The URM09 sensor showed outstanding consistency and stability across all test distances (near, mid, and long). Particularly in the long-range test, the sensor performed almost perfectly, highlighting its suitability for long-distance monitoring applications. Although the mid-range measurements were slightly higher, its consistency ensured applicability in situations requiring high reliability.

• HC-SR04

The HC-SR04 sensor demonstrated excellent consistency in near to mid-range tests, but the accuracy decreased at longer distances. This characteristic makes the HC-SR04 particularly suitable for near to mid-range applications, such as obstacle detection and indoor positioning. Its affordability and robust performance also make it a preferred choice for DIY projects and educational purposes.

• Devantech: SRF02

The SRF02 sensor maintained a high level of consistency across the full range of tests, although the measurements were slightly higher from mid to long distances. Its compact design and reliable performance are especially suited for applications where space is limited and consistency is sought.

• Maxbotix: LV-EZ4 MB1040

The Maxbotix LV-EZ4 showed the closest accuracy to the actual distance in mid-range tests but performed slightly less well at closer or longer test distances. The high precision measurements and stable output of the LV-EZ4 make it an ideal choice for high-end applications requiring fine mid-range measurements.

3.2.2 Data Jitter Test

This test is designed to evaluate the data stability of ultrasonic sensors during the measurement process. In real-world applications, the measurement data from sensors can be affected by various factors, such as environmental noise, temperature fluctuations, or unstable power supply, leading to data instability. To accurately assess the performance of the sensors in a controlled environment, we conducted a data stability test.

The test environment was set up with the sensor in a fixed position, facing a wall, to measure data stability at different distances (50cm and 3m). During the test, the sensor's readings were recorded every 30 seconds to observe whether there were significant jitters or fluctuations in multiple measurements under the same conditions.

Figure：Comparison table of four ultrasonic data (50cm)

Figure：Comparison table of four ultrasonic data (3m)

The test results indicate that even for the same ultrasonic sensor, the stability of the data output can vary at different measurement distances. As shown in the figure above, the MB1040 sensor displayed higher data stability in long-distance measurements. In contrast, at closer distances, the SR04 sensor exhibited more prominent data stability.

Summary

Through the introductions and test analyses provided above, we can see that the URM, HC-SR04, Devantech, and Maxbotix ultrasonic sensors each have their unique advantages and suitable applications. The URM series excels with its long-distance monitoring capability and consistency, making it suitable for industrial and robotics applications that require high precision. The HC-SR04 is an ideal choice for educational and DIY projects due to its cost-effectiveness and stability at near to mid-range distances. Devantech sensors, with their high consistency and compact design, are suitable for professional applications where space is limited. Meanwhile, Maxbotix sensors meet the needs of the high-end market with their accuracy and stability at mid-range distances.

Choosing the right ultrasonic sensor requires consideration of the specific needs of the application, including measurement distance, precision, environmental conditions, interface type, and budget. With the introduction and test analysis in this article, we hope to provide valuable references to help you make an informed choice among the many ultrasonic sensor products available. Whether in industrial automation, IoT devices, robotics, or the fields of education and research, accurately selecting the appropriate ultrasonic sensor is key to ensuring the success of your project.

As technology continues to advance and innovate, we look forward to ultrasonic sensors providing even higher performance, a broader range of applications, and continuing to contribute to the development of various industries in the future.