Application solutions for ultrasonic sensors in robots

- Jun 04, 2019-

ultrasonic sensors in robots

The robot is a complex computer controlled by a computer. It has human-like limb and sensory functions; the action program is flexible; there is a certain degree of intelligence; and it can be manipulated without human intervention. Robotic sensors play a very important role in the control of robots. Because of the sensors, robots have the same human perception and responsiveness. Therefore, robots can replace or assist humans in all kinds of work. Any boring, dangerous, toxic, and harmful work can be shown by robots. In addition to being widely used in the manufacturing industry, robots are also used in resource exploration and development, disaster relief, medical services, home entertainment, military and aerospace. Robots are important production and service equipment for industrial and non-industrial industries, and are also indispensable automation equipment for advanced manufacturing technology. This article is mainly for a simple introduction of ultrasonic sensors in the application of the machine.

Ultrasonic sensors are one of the commonly used sensors for obstacle avoidance and ranging in mobile robots. At the same time, it is also used to measure the distance of the object. First, the ultrasonic sensor will emit a set of high-frequency sound waves, generally 40-45KHz. When the sound wave encounters the object, it will be bounced back and accepted. By calculating the time from the sound to the return of the sound wave, multiply by the speed of the sound wave in the medium (344 m / sec, in the air). The distance value of the object relative to the sensor can be obtained. In practical applications, for the application of the robot, the ultrasonic sensor is mainly used to detect the distance of the object and the orientation with respect to the sensor, so that the obstacle avoidance action can be performed. The ideal is a rectangle, which not only can accurately obtain the distance value of the object, but also accurately obtain the orientation value, which is directly in front. But in reality, the beam of the ultrasound has a wide beam and a narrow beam depending on the application. If the object being detected is in the proper angle, the ultrasonic sensor will get the correct test result. However, if the angle of the measured object is deviated, the measurement result of the sensor will contain an error. Errors that may occur include triangular errors, specular reflections, multiple reflections, and the like. Therefore, when the sensor is mounted on the robot, it should not be too close to the ground, too close to the interference signal, and it is easy to treat the obstacle that can be overturned as an insurmountable obstacle. The distance between the two probes of the sensor should not be too far or too close, too far measurement error is too large, too close crosstalk signal is too strong.


In the use of ultrasonic sensors, the following problems should be considered: First, most ultrasonic sensors operate at a frequency of 40-45 Khz, far exceeding the frequency range that can be heard by the human ear. However, the surrounding environment sometimes produces noise of similar frequency. These noises can affect the measurement results of the ultrasonic sensor. At this time, it can be solved by encoding the transmitted ultrasonic waves, such as transmitting a set of sound waves of different lengths, and the distance calculation is performed only when the probe detects the same combined sound wave. This can effectively avoid misreading caused by environmental noise. Secondly, when multiple ultrasonic sensors work together, it is also necessary to pay attention to the accuracy of the measurement results due to the reflection of sound waves. This effect can be eliminated by careful design of the position of the ultrasonic sensor and its own performance indicators. The size of the last measured object will also have a certain impact on the detection capability of the ultrasonic sensor. Generally speaking, for the same ultrasonic sensor, the larger the volume of the measured object, the larger the reflected ultrasonic echo, and the farther the corresponding detection distance will be. Conversely, when the measured object is small, the detection distance of the ultrasonic sensor will be relatively close.

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