Ultrasonic sensor modules for robots

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Ultrasonic sensor modules for robots [Copy link]

With the promotion and application of sensor technology, the development of robots has also attracted much attention. At the same time, the progress of sensor technology has also supported the development of industrial robots. It can be seen that sensors have made great contributions to promoting the rapid and orderly development of China's robot industry. The ultrasonic sensor used in the robot is an electronic module with a measurement distance between 3cm and 400cm. It can be used to help the robot avoid obstacles, or for distance measurement and obstacle avoidance engineering in other related projects. The sensor can be said to be the core component used to detect the working status of the robot itself, as well as the robot's intelligent detection of the external working environment and the state of the object. It is a device or device that can not only sense the specified measured value, but also convert it into a usable output signal according to certain rules.

Since ultrasonic waves have strong directivity and can travel a long distance in a medium, they are often used to measure distances. For example, distance meters and level meters can all be measured using ultrasonic waves. Ultrasonic detection is often quick, convenient, simple to calculate, easy to achieve real-time control, and can meet industrial practical requirements in terms of measurement accuracy. Therefore, it has also been widely used in the development of mobile robots.

In order for a mobile robot to automatically avoid obstacles and walk, it must be equipped with a distance measurement system so that it can obtain distance information (distance and direction) from obstacles in a timely manner. The ultrasonic ranging system in three directions (front, left, and right) provides a movement distance information for the robot to understand the environment in front, on the left, and on the right. The ultrasonic sensor can be used alone as an ultrasonic ranging after being connected to the power supply. The ultrasonic sensor can also be specified to output segmented distance detection signals from the I/O port of the microcontroller. It can be directly installed on the robot for applications such as object search and obstacle avoidance detection. Let's take the Korean Hagisonic robot ultrasonic sensor module - HG-M40 series and HG-L40 series to understand the specific solution of the ultrasonic sensor module for robots.

1. Robot ultrasonic sensor module - HG-M40 series, HG-L40 series product features

Detect objects, measure distance

Mid-range

Multi-directional

Low "click noise"

Indoor environment

Minimize dead zone

Real-time signal (5V TTL)

Works at 40kHz

3 modules  Transceiver (HG-M40D)  Transmitter (HG-M40T)  Receiver (HG-M40R)

2. Principle of Ultrasonic Distance Measurement

The ultrasonic transmitter transmits ultrasonic waves in a certain direction. At the moment of transmission, the counter starts timing. The ultrasonic waves propagate in the air. If they encounter obstacles on the way, they are immediately reflected back. When the two ultrasonic receivers receive the reflected waves, they stop timing immediately and measure the ratio of the distance and flight time of each path (P1+P2, P1+P3). The propagation speed of ultrasound in the air is 340m/s. According to the time t recorded by the timer, the distance s between the emission point and the obstacle surface can be calculated, that is: s=340t/2.

III. Robot ultrasonic sensor module - HG-M40 series, HG-L40 series module and mode differences

1. Module

① Transceiver (D):  It can be used not only as a transceiver module, but also as a receiver or transmitter under different wiring methods. Because the transceiver has to send out ultrasonic waves and wait for a reply, it can detect distances of 30cm~40cm and farther. In any case, it will try its best to identify whether an object is somewhere. ② Transmitter (T) :Transmits ultrasonic waves only.

③ Receiver (R) : Receives ultrasonic waves only.

※ When using 2 or more sets of transmitters and receivers, close range detection of 1~2cm is possible.

※ Similarly, if a transceiver is used, obstacles as short as 1~2Cm can be detected when it is used independently as a transmitter or receiver. 2. Modes Trigger input mode (M-type) Pulse train input mode (L-type) 3. The difference between M-type and L-type. ... Ultrasonic sensors have certain diffusion characteristics. The emitted ultrasonic energy is mainly concentrated on the main lobe, and decays in a wave-like manner along both sides of the main wave axis, with a diffusion angle of about 60° (conventional) (optional). In fact, the distance calculation is based on the successful and vertical reflection of the ultrasonic wave. However, it is difficult for mobile robots to ensure the stability of their own motion posture. When the mobile robot deviates from the parallel wall, the detection system often finds it difficult to obtain the actual distance by using an ultrasonic sensor fixed on the body of the mobile robot. In addition, when the ultrasonic divergence characteristic is used to measure obstacles, it can only provide distance information of the target obstacle, but not the direction and boundary information of the target. Therefore, multiple ultrasonic sensors and other sensors are needed to work together.

star_66666

Very good stuff

长沙湖重机电

Very insightful explanation, thanks for sharing.