Collision warning radar

Purpose:
With the popularity of aerial work vehicles, the potential safety hazards caused by workers touching wires (conductors) or poles in the air have greatly increased. At the same time, there are certain safety issues in such buildings, industrial and mining operations, etc. Ultrasonic radar is used to monitor the distance between the aerial work vehicle and the high-voltage wires (or obstacles), and the workers can receive distance information at any time, which will greatly reduce the probability of such safety accidents.
Design idea:
In order to ensure the safety of workers during operation, we proposed to design a set of anti-collision warning device, which has 11 ultrasonic slaves and a display host. Compared with one ultrasonic ranging, the ranging of 11 ultrasonics is more accurate and has a wider range than one. The display screen of the host can also allow monitoring personnel to better know the distance between the aerial work vehicle and the surrounding obstacles. The device is expected to realize ultrasonic ranging, alarm when it is less than a certain distance, and transmit all slave data to the host serial port screen through the wireless module. In order to facilitate the staff to check whether it needs to be charged, the battery voltage is detected by the function of the main control chip and sent to the host serial port screen through the wireless module.
Design plan:
I. Hardware:
1. Overall plan
2. Hardware design of each module
(1) The lithium battery voltage charging module
uses TP4056 as the main charging chip of the module. The chip has functions such as automatic temperature adjustment and fixed charging voltage. It is easy to use and does not require external detection resistors and isolation diodes. The charging current can be set externally through a resistor. In the module circuit, the CHRG pin of the TP4056 chip is connected in series with the red light, and the STDBY pin is connected in series with the green light. When the battery is not fully charged, the red light is on; when the battery is fully charged, the green light is on. In order to consider the battery recharging time and the temperature of the chip, the PROG pin of the chip is connected in series with a 2.4K resistor, and the charging current is 500mA. The capacitor in the circuit plays a filtering role.
(2) The main control chip
This work uses the STC8H3K64S2 microcontroller. This work does not need to use a large number of IO ports of the microcontroller, so the 20 IO ports of the microcontroller can meet the requirements. In addition, the single-chip microcomputer has a serial port and an internal AD conversion module, which can meet the hardware design of the ultrasonic distance measurement module, LCD display and lithium battery voltage detection module. Its small size and low price are also its advantages. The small size can leave space for placing other module components, and the low price can save costs.
(3) The LCD display
uses Taojingchi's 2.4-inch USART HMI resistive touch screen. The module is easy to use and can transmit data through string instructions. You can first customize the page through its self-developed interface development software, set multiple pages to display multiple data, customize the font size, adjust the brightness, and have rich colors. There are four pins on the module, 5V and GND for power supply, RX and TX for single-chip microcomputer data transmission. The module is connected to the circuit board for use, and only a 4P pin header needs to be designed on the circuit board. The specific design is shown in the figure.
(4) The ultrasonic distance measurement module
considers the measurement accuracy, anti-interference ability and low power consumption. The JSN-SR20-Y1 waterproof and dustproof ultrasonic distance measurement module is selected. The module uses dual probes and has strong adaptability to the working environment. This type of ultrasonic wave also needs to be triggered by sending a signal through the serial port, so the pins used are similar to those of the LCD screen. However, considering the pursuit of a small size, the pin header is replaced with a female header. The ultrasonic wave only needs to be inserted into the female header to work.
(5) Sound and light indication and alarm circuit design
Sound and light indication and alarm are activated by the operation indicator light, power indicator light, distance alarm indicator light and buzzer due to different factors to play a warning role. The sound and light indication and alarm circuit design is shown in Figure 7. Three LED indicators are connected in series with a 1K resistor, and the resistor mainly plays a current limiting role. The microcontroller controls the three indicators separately. The operation indicator light LED6 is connected to the microcontroller P1.6, the power indicator light LED5 is connected to the microcontroller P3.1, and the distance alarm indicator light LED3 is connected to the microcontroller P3.0. The microcontroller can be programmed to output a high level to light up the indicator light. The operation of the buzzer is controlled by a transistor. The base of the transistor Q3 is connected to the microcontroller P3.2. When the P3.2 pin inputs a high level, the transistor is turned on to form a loop and the buzzer is activated. Diode D1 protects the transistor from being broken down by reverse current.
(6) Wireless communication module circuit design
The slave needs to transmit various data to the host. By comparing the communication distance, transmission frequency and price of various wireless transceiver chips, the domestic Si24R1 is selected as the chip of the wireless communication module. The interface circuit of the wireless communication module is shown in Figure 8. The chip enable pin CE of Si24R1 is connected to P1.2 of STC8H3K64S2. When the chip is at a high level, the chip turns on the signal and activates the RX or TX mode; the chip select pin CSN is connected to P3.7. When CSN is at a low level, the chip starts working. At this time, CE cooperates with the register to determine the state of Si24R1; the clock pin SCK is connected to P3.6; the MOSI and MISO pins are connected to P3.5 and P3.4 respectively; the interrupt request signal pin IRQ is connected to P3.3. When the chip receives information, the information is sent and an automatic response is received, or the maximum number of retransmissions is exceeded, a low level is generated, and an interrupt signal is issued.
II. Software:
(1) Host software design flow chart
(2) Host software design flow chart
 
Application value:
1. High safety. During power inspection, many transmission lines still need manual maintenance. Maintenance personnel take aerial work vehicles to the transmission lines that need maintenance. The voltage level of the transmission line is high. Our device can detect the distance between the aerial work vehicle and the transmission line. When the distance is too close, an alarm is issued to remind the operator to reduce the danger.
2. Accurate distance. Since the diameter of the transmission line conductor is not large, the hardware of a single ultrasonic wave itself is limited, and the measurement is limited. It cannot accurately express the distance between the aerial work vehicle and the conductor, and the safety is low. Therefore, we use multiple ultrasonic waves to make the collected data more accurate. When applied to the aerial work vehicle, the distance between the aerial work vehicle and the conductor can be measured more accurately, reducing the risk of workers during operation.
3. Wide application. It can be used not only in the power industry, but also in any aerial operation and construction operations to detect the distance between the aerial work vehicle and the object, which is convenient for workers to operate, so that the personal safety of workers is guaranteed, improve work efficiency, and reduce employment costs.
4. Wireless devices. Most of the distance measuring devices on the market are currently wired. We use wireless modules for data transmission. The host communicates wirelessly with each slave. Each slave is also equipped with a wireless communication module, which is convenient for use in various occasions, easy to carry and operate, and the overall aesthetics is greatly improved.
5. Low power consumption. We use the host to wake up the slave. When the host does not send a signal to the slave, the slave will remain in standby mode until the host sends a signal to wake up, so as to achieve low power consumption. In the non-standby state, an 850mAh rechargeable lithium battery can provide the slave with about 42.5 hours of continuous work. After increasing low power consumption, the endurance will be greatly improved, which is convenient for staff to use continuously and prolong battery life.