Disadvantages of ultrasonic sensor
Ultrasonic sensors use ultrasonic waves to find the position, distance, or movement of objects. Experts use them in many fields, like weather, industry, cars, and healthcare. However, like all technology, these sensors have some downsides. The main drawbacks of ultrasonic sensors are listed below:
1. **Susceptibility to Environmental Factors**
– **Temperature and Humidity:** The performance of ultrasonic sensors can drop with changes in temperature and humidity. This can lower measurement accuracy.
– **Medium Variability:** The speed of ultrasonic waves varies in different materials. Changes in the medium, like gas type or pressure, can affect measurement results.
2. **Sensitivity to Surface Roughness**
Rough surfaces can scatter or weaken the reflected ultrasonic waves. This leads to lower measurement accuracy.
3. **Ranging Blind Spot**
Since the same transducer sends and receives waves, it needs a short conversion time. Because of this, at very close distances, the system might not get the returning waves in time. This creates a measurement blind spot.
4. **Beam Diffusion and Directionality**
Ultrasonic sensors have a set beam angle. This affects how well they measure orientation. They can only provide an estimated distance to objects. The spread of the beam can also cause more measurement errors.
5. **Triangulation Errors**
In some cases, ultrasonic waves do not travel in straight lines. They can bend or scatter instead. This can cause errors in triangulation measurements.
6. **Interference Sensitivity**
During operation, ultrasonic sensors can be affected by environmental factors. Mechanical vibrations and electromagnetic noise can interfere with them. These disturbances can hide or change the ultrasonic signal, which reduces accuracy.
7. **Measurement Speed Limitation**
Ultrasonic sensors are slower than laser or millimeter-wave systems. This means they are not good for tasks that need quick, real-time measurements.
8. **Directional Constraints**
Ultrasonic sensors have narrow beams for sending and receiving signals. This limits their ability to detect objects in certain directions. Objects outside this narrow range might not be detected.
9. **Multipath Effects**
In places with many reflective surfaces, ultrasonic signals can bounce in different ways. This causes complex wave reflections that can affect sensor accuracy.
10. **Power Consumption**
The energy needed to send and receive ultrasonic signals can be quite high. This creates a challenge for battery-powered devices.
11. **Cost Considerations**
Ultrasonic sensors can be more expensive than other types of sensors. This is especially true for tasks that need long-range detection or high precision.
ultrasonic sensor specification
Measuring Range
Typical range: Usually from a few centimeters to several meters. For example, some common ultrasonic sensors measure from 2 to 500 cm or from 5 to 800 cm. The exact range depends on the sensor’s design and use.
Accuracy: The measurement accuracy is usually within a few millimeters to a few centimeters. High-precision ultrasonic sensors can reach an accuracy of ±1 to 2 mm. More general-purpose sensors may have an accuracy of ±5 to 10 mm.
Frequency
Operating frequency: Ultrasonic sensors work at frequencies higher than what humans can hear. They usually operate between 20 kHz and 200 kHz. Common frequencies are 40 kHz, 58 kHz, and 80 kHz. The frequency chosen impacts the sensor’s performance. This includes its range, resolution, and sensitivity to various materials.
Bandwidth: The bandwidth of the sensor is the range of frequencies it can use to send and receive ultrasonic signals. A wider bandwidth can give better resolution and a higher signal-to-noise ratio. However, it may also need more complex signal processing.
Resolution
Distance resolution: This is the smallest change in distance that the sensor can detect. It is related to the sensor’s accuracy and the wavelength of the ultrasonic wave. Generally, the higher the frequency of the ultrasonic wave, the better the distance resolution. For example, a 40 kHz ultrasonic sensor may have a distance resolution of around 1 – 2 mm.
Angular resolution: In some applications, such as ultrasonic imaging or object detection in a specific direction, the angular resolution of the sensor is important. It refers to the ability of the sensor to distinguish between objects at different angles. The angular resolution depends on the size and shape of the sensor’s transducer and the beam pattern of the ultrasonic wave.
Power Supply
Voltage requirements: Ultrasonic sensors typically operate at a specific voltage, which can range from a few volts to several tens of volts. Common voltage levels include 3.3 V, 5 V, 9 V, and 12 V. It is important to provide the correct voltage to ensure the proper operation of the sensor.
Current consumption: The current consumption of the sensor varies depending on its operating mode and the complexity of its circuitry. When the sensor is actively transmitting and receiving signals, it will consume more current than when it is in a standby or low – power mode. Typical current consumption values can range from a few milliamperes to several hundred milliamperes.
ultrasonic sensor specification Output Signal
Analog output: Many ultrasonic sensors provide an analog output signal that is proportional to the measured distance. The output voltage or current can be in the range of 0 – 5 V, 0 – 10 V, or other standard ranges, depending on the sensor’s design. This analog signal can be easily interfaced with microcontrollers or other analog – to – digital conversion circuits for further processing.
Digital output: Some ultrasonic sensors offer digital output interfaces, such as PWM (Pulse – Width Modulation), I²C (Inter – Integrated Circuit), SPI (Serial Peripheral Interface), or UART (Universal Asynchronous Receiver – Transmitter). Digital output allows for more accurate and convenient communication with microcontrollers and other digital devices, and can also provide additional features such as multiple measurement modes and sensor configuration options.
Physical Characteristics
Size and shape: Ultrasonic sensors come in various sizes and shapes, depending on their intended application. They can be small and compact for use in portable devices or embedded systems, or larger and more robust for industrial applications. Common shapes include cylindrical, rectangular, and square.
Material and construction: The housing of the ultrasonic sensor is usually made of durable materials such as plastic, metal, or a combination of both. The transducer, which is responsible for generating and receiving the ultrasonic waves, is typically made of piezoelectric materials. The construction of the sensor should be able to withstand the environmental conditions in which it will be used, such as temperature variations, humidity, and mechanical vibrations.
Environmental Conditions
Operating temperature range: Ultrasonic sensors are designed to operate within a specific temperature range. This range can vary depending on the sensor’s components and materials. Typically, the operating temperature range is from – 20°C to 60°C or – 40°C to 85°C for more extreme – environment – capable sensors. Outside of this range, the performance of the sensor may be affected, and it may even be damaged.
Humidity and waterproofing: The sensor should be able to withstand different levels of humidity without affecting its performance. Some ultrasonic sensors are designed to be waterproof or at least water – resistant, which is important for outdoor or wet – environment applications. Waterproof sensors are usually rated according to an IP (Ingress Protection) code, such as IP67 or IP68, indicating their level of protection against water and dust.
ultrasonic sensor specification Conclusion
Ultrasonic sensors are useful in many industries, but they have some limitations. These include being sensitive to the environment, having blind spots, and facing directional issues. Interference can also affect them, they can have slower measurement speeds, and they often cost more.
To get the best results in real-world use, it is important to choose the right sensor type. You should also set its parameters based on the specific environment and needs. Addressing these limitations through careful planning can enhance both measurement accuracy and overall system reliability.
