CN110868566A - Wireless video transmission method for transformer internal inspection robot - Google Patents

Abstract

The invention relates to a wireless video transmission method of a transformer internal inspection robot. The embedded technology is combined with the Internet of things technology, and the wireless video transmission under the complex condition is realized by utilizing the MICO Internet of things real-time operating system. The modular design is adopted, the data acquisition terminal is divided into an upper computer control terminal and a lower computer data acquisition terminal, the lower computer is used for acquiring, processing and transmitting video data, and the upper computer is used for receiving and displaying videos. The invention uses DAM double-buffer mode to buffer data, realizes the parallel operation of data acquisition and output, and greatly reduces the load of the processor. The invention can realize wireless real-time transmission of image video information in the closed environment under the closed metal shielding environment.

Description

A wireless video transmission method for transformer internal inspection robot

technical field

The invention relates to a video transmission method, in particular to a wireless video transmission method of a transformer internal inspection robot.

Background technique

In the operation and maintenance of today's power equipment, the transformer is not only one of the most important and expensive equipment in the power system, but also one of the equipment that causes many accidents in the power system. Its reliability is directly related to the power grid energy. safe, efficient and economical operation. According to the requirements of the maintenance procedures for large power transformers, it is necessary to carry out hood maintenance every 5 years. The internal inspection method of unpacking the hood has the advantages of accurate and thorough fault detection, but there are disadvantages such as very high on-site internal inspection costs and long construction period. If it is possible to obtain useful information inside the transformer without unpacking the hood, it will be a revolutionary change in transformer maintenance. Due to the complex internal environment of the transformer and the good airtightness inside the container, the traditional wired transmission method will be difficult to achieve, which makes it difficult to transmit the information collected by the transformer internal inspection robot inside the transformer, especially the video information, to the external environment.

How to transmit the video information collected by the internal inspection robot inside the transformer to the external environment is a key problem that needs to be solved urgently.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a wireless video transmission method for a transformer internal inspection robot, so as to solve the problem that the video information collected by the transformer internal inspection robot inside the transformer is difficult to transmit to the external environment.

The present invention is realized as follows: a wireless video transmission method for a transformer internal inspection robot, comprising the following steps:

a. Set up an internal inspection robot in the transformer, and set a lower computer on the internal inspection robot, and set up an upper computer and a router connected to the upper computer outside the transformer. The lower computer includes a core controller, an image acquisition module, a wireless transmission module, The power supply module, the lower memory module and the SDRAM module, and the upper computer includes a control module, a display module and an upper memory module;

b. Transplant the MICO system to the core controller of the lower computer;

c. Initialize the MICO system and enter the main program loop;

d. Call the subroutine to initialize the SDRAM;

e. Call the subroutine to connect the wireless network, so that the wireless transmission module of the lower computer is connected to the router;

f. Call the subroutine to prepare the memory space of the data cache for the image acquisition module, set the data cache area on the SDRAM, and divide the data cache area into two cache areas;

g. Call the subroutine to initialize the image acquisition module, and turn on the camera to start image acquisition;

h. Call the subroutine to create a TCP service thread, and wait for the upper computer control module to connect with the lower computer through the router;

i. The upper computer is connected to the lower computer, and the data buffer area opens the DAM double buffer mode to buffer the image data stream from the image acquisition module, and starts video transmission.

After each subroutine is called, it is judged whether the subroutine returns an error. If the subroutine returns an error, the status information is output through the serial port. If the subroutine returns no error, the next subroutine is called; when creating a TCP service thread subroutine , if the return is correct, the IP address and port number of the TCP service will be output through the serial port, while waiting for the host computer to connect.

The two buffer areas divided in step f are the first buffer area and the second buffer area respectively; in step i, after video transmission is started, the first buffer area is first used to store data, and when the first buffer area is full, the DMA Switch to the second buffer area and use the second buffer area to store data. At this time, the CPU of the core controller reads the data in the first buffer area and transmits the data to the upper computer through the wireless network; when the second buffer area is filled After it is full, the DMA switches to the first buffer area, uses the first buffer area to store data, the CPU of the core controller reads the data in the second buffer area, and transmits the data to the upper computer through the wireless network; repeat the above process continuously, until the video transfer task is completed.

In step e, the main program calls the WIFI connection network connection subroutine, reads the preset parameter values in the external FLASH, including the router name and network connection password, initializes the WLAN parameters and network protocol stack, and then performs network connection, and judges Whether the connection is successful, if the connection is successful, the IP and port number of the terminal in the current network will be obtained, and uploaded to the host computer through the serial port transparent transmission module. If the connection fails, the connection failure information will be output through the serial port.

In step g, first call the camera subroutine to open the camera, configure interrupt, DMA, DCMI related initialization parameter settings, configure the camera parameters, then restart the camera and read the camera ID to determine whether the reading is successful, if it fails, output an error message, If successful, configure the format of the camera output data and the resolution of the output image, set the DCMI camera interface of the core controller to the same format as the camera output, receive the data from the camera, enable the DCMI continuous image capture function, and enable the DCMI interface to complete the transmission preparation of the video stream.

The data filling algorithm of DAM is as follows:

Set the loading times of the DMA counter to 1, and calculate the initial value of the counter required to fill the buffer area according to the number of bytes transferred by DMA at a time. If the initial value of the required counter is less than or equal to the threshold value of the counter, the buffer area can be filled by loading the counter once. If the initial value of the required counter exceeds the counter threshold, divide the initial value of the required counter by 2, multiply the number of loading times by 2, and compare the new initial value of the counter obtained by dividing the initial value of the required counter by 2 with the counter threshold, and continuously Repeat the above process until the initial value of the counter is less than or equal to the counter threshold.

In the invention, the internal inspection robot enters the inside of the transformer for image acquisition and processing, and then the data is transmitted to the upper computer through the wireless network, and the upper computer displays the image information collected by the lower computer, thereby realizing the wireless real-time transmission of the internal video of the transformer. Combining embedded technology with Internet of Things technology, using MICO Internet of Things real-time operating system to achieve wireless video transmission in complex situations. The modular design is adopted, which is divided into the upper computer control terminal and the lower computer data acquisition terminal, which realizes the collection, processing and transmission of video data by the lower computer, and the reception and display of the video by the upper computer. In order to ensure that the MICO system can run stably on the core controller, an external SDRAM chip is expanded. The invention uses the DAM double buffer mode to buffer data, the DAM is responsible for filling the data buffer area, the CPU is responsible for network data transmission, realizes the parallel operation of data acquisition and output, and greatly reduces the load of the processor.

The invention can realize wireless real-time transmission of image and video information in the closed environment under the closed metal shielding environment.

Description of drawings

FIG. 1 is a schematic diagram of a video transmission system of the present invention.

FIG. 2 is a flow chart of the video transmission of the present invention.

FIG. 3 is a flow chart of the network connection of the present invention.

Fig. 4 is a flow chart of the image acquisition of the present invention.

FIG. 5 is a flow chart of the TCP transmission service of the present invention.

FIG. 6 is a flow chart of the DMA double buffer mode of the present invention.

FIG. 7 is a flow chart of the DMA data filling algorithm of the present invention.

Detailed ways

The present invention includes the following steps:

a. Set up an internal inspection robot in the transformer, and set a lower computer on the internal inspection robot, and set up an upper computer and a router connected to the upper computer outside the transformer. The lower computer includes a core controller, an image acquisition module, a wireless transmission module, The power supply module, the lower memory module and the SDRAM module, and the upper computer includes a control module, a display module and an upper memory module;

b. Transplant the MICO system to the core controller of the lower computer;

c. Initialize the MICO system and enter the main program loop;

d. Call the subroutine to initialize the SDRAM;

e. Call the subroutine to connect the wireless network, so that the wireless transmission module of the lower computer is connected to the router;

f. Call the subroutine to prepare the memory space of the data cache for the image acquisition module, set the data cache area on the SDRAM, and divide the data cache area into two cache areas;

g. Call the subroutine to initialize the image acquisition module, and turn on the camera to start image acquisition;

h. Call the subroutine to create a TCP service thread, and wait for the upper computer control module to connect with the lower computer through the router;

i. The upper computer is connected to the lower computer, and the data buffer area opens the DAM double buffer mode to buffer the image data stream from the image acquisition module, and starts video transmission.

As shown in FIG. 1 , the present invention first proposes a video transmission system for a transformer internal inspection robot, which includes an upper computer, a lower computer and a router. The upper computer is the software air control center of the wireless transmission system, and it solves the video data transmitted from the lower computer terminal. The lower computer is a video acquisition terminal, which is wirelessly connected to the upper computer, detects the internal environment of the transformer in real time and transmits the video information to the upper computer, so as to realize the inspection of the inside of the transformer.

Among them, the host computer includes:

The control module is responsible for establishing the connection between the upper computer and the lower computer and receiving the status information returned by the lower computer;

The display module displays the video information transmitted from the lower computer in real time;

The upper storage module stores the received information.

The lower computer includes:

The core controller, specifically using STM32F429IGT6 single-chip microcomputer, is responsible for driving the image acquisition module for image acquisition and processing;

The image acquisition module is connected to the core controller through the unique DAMI interface of the STM32F4 series single-chip microcomputer, and collects the image information of the internal environment of the transformer in real time;

The wireless transmission module is connected to the main control chip through the SDIO interface, which is used for remote data transmission and communication between the upper computer and the lower computer;

The power module, including the conversion module, supplies power to the core controller, the wireless transmission module and the image acquisition module;

The SDRAM module is an external expansion of an SDRAM chip for the STM32F4 series single-chip microcomputer, which is used for data cache. The specific model is IS42S16400J.

The wireless transmission module of the present invention selects the WIFI module with SDIO interface. The traditional WIFI module adopts the data transmission method of serial port to WIFI, and its speed is only the transmission speed of ordinary serial port, which is suitable for occasions with less data and low real-time performance, while SDIO interface The data transmission speed of the WIFI module can reach up to 24MB, which meets the requirements of video transmission speed.

The invention uses the MICO Internet of Things real-time operating system, and needs to transplant the MICO system on the transformer internal inspection robot video transmission system first, and the specific steps are as follows:

Step 1, do the preparatory work, prepare MiCOKit kit, Keil5 development software and related hardware equipment;

Step 2, allocate storage space, divide FLASH into BootLoader area, Application area and RF firmware area;

Step 3, transplant BootLoader, add a new hardware platform in MiCOKit, and modify the corresponding code according to the hardware parameters of the lower computer terminal to make BootLoader match our terminal hardware;

Step 4: Transplant the Application, and select the transplanted application according to the actual application. The transplanted Application is similar to a new project, including the configuration of related parameters such as file creation, chip selection, header file path selection, and FLASH storage space allocation.

As shown in Figure 2, the transmission method of the present invention mainly includes:

Step 1. After the lower computer terminal is powered on, the initialization of the MiCO system, peripherals and other external devices is completed under the control of the main control chip, mainly including the configuration of SPI, SDIO, USART, and watchdog;

Step 2: After the initialization is completed, the system enters the main program loop, initializes the SDRAM, and judges whether the SDRAM initialization is normal through the API subroutine provided by the MiCO system. If the subroutine initialization error occurs, the main program outputs the relevant information through the serial port;

Step 3, after the SDRAM initialization is completed, and then determine whether the WIFI chip has been connected to the specified wireless network through the return value of the subroutine, no matter whether the device is successfully connected to the router, the serial port will output the relevant information of the connection status;

Step 4, prepare the memory space of the data cache for the camera, establish two data buffer arrays and clear the cache, and obtain the address of the cache area for subsequent writing of video stream data;

In step 5, the subroutine is called to initialize the camera, including initialization of the camera interface, configuration of the camera output format and other related parameter settings.

Step 6, create a TCP service thread, the main program judges whether there is an error in the subroutine, if there is an error, the serial port outputs an error message, if there is no error, the main program serial port outputs the IP address and port number of the TCP service. At this time, the lower computer terminal becomes a TCP server waiting for the connection of the remote user, that is, the upper computer control terminal, and provides video transmission services.

During the running process of the main program, after each subprogram is called, it is judged whether the subprogram returns an error. If the subprogram returns an error, the status information is output through the serial port. If the subprogram returns without error, the next subprogram is called.

As shown in Figure 3, the network connection process of the present invention is as follows:

Step 1, the lower computer control main program calls the WIFI network connection subroutine to create a structure array to store the parameters required for the wireless network connection;

Step 2, read the preset parameter value of external FLASH, including router name and network connection password;

Step 3, initialize the WLAN parameters, and set the relevant parameters of the WIFI chip, including channel selection, security mode, station or AP mode, and waiting time for connection failure and reconnection attempt time;

Step 4, initialize the network protocol stack;

Step 5: Connect to the network and determine whether the connection is successful. If the connection is successful, the program will obtain the terminal's current network IP and port number and upload it to the host computer through an external transparent transmission module through the serial port. If the connection fails, the information of connection failure will be output through the serial port.

As shown in Figure 4, the present invention uses the JPEG compression encoding format as the output format of the data collected by the camera, and in the main program, the camera is configured and used by calling the camera subroutine, and the steps include:

Step 1, call the camera subroutine to configure and open the camera;

Step 2, enter the subroutine configuration interrupt, DMA, DCMI related initialization parameter settings, including clock, GPIO, working mode, etc.;

Step 3, configure the camera parameters, initialize the camera SCCB bus, and verify whether the MCU and the camera can communicate normally;

Step 4, restart the camera, read the camera ID number, and judge whether the reading is successful by comparing it with the ID information provided by the official;

Step 5, configure the format of the camera output data;

Step 6, set the camera output image resolution;

Step 7, set the DCMI camera interface of the core controller to JPEG format, and receive the data transmitted by the camera;

Step 8, setting the DCMI interface to continuous capture mode for data reception;

In step 9, the DCMI interface is enabled, and the image acquisition of the lower computer can transmit the video stream with the upper computer.

As shown in Figure 5, the TCP transmission service process of the present invention is as follows:

Step 1, the main program creates a TCP service thread by calling the API provided by the MiCO system;

Step 2, read the local IP address and preset port number of the WLAN connection, and create a socket;

Step 3, bind the obtained IP address and port number;

Step 4: After completing the above operations, the server enters the monitoring state and waits for the handshake request sent by the host computer;

Step 5: After the connection is successful, the terminal starts video capture;

Step 6, the TCP server thread reads the data from the buffer area, transmits it to the host computer through the wireless network, and displays the collected video information after decoding by the host computer software.

When performing video transmission, the data is read from the camera, and each time it needs to be processed and stored by the CPU of the core controller and then sent out through the WIFI chip, which will greatly increase the load on the processor. If DMA is used The double-buffer mode buffering data can solve this problem very well, in which the DMA is responsible for filling the data buffer, and the CPU is responsible for the transmission of network data, thus realizing the parallel operation of data acquisition and output. The invention applies the double buffer mechanism to buffer the collected video data, and designs the buffer filling related algorithm of the DMA of the STM32F4 series single-chip microcomputer, so that the size of the terminal buffer area can be adjusted online.

As shown in Figure 6, the DMA double buffer mode of the present invention is as follows:

Step 1, the data acquisition end expands an 8MB SDRAM as a data buffer area. Due to the double buffer mechanism, it is divided into two 4MB buffer areas, namely the first buffer area Data_Buff1 and the second buffer area Data_Buff2.

Step 2: Turn on the DMA double buffer mode on the STM32F429, and set the DBM bit of the register DMA_SxCR to 1. At this time, the DMA controller will also automatically activate the loop mode;

Step 3. After the video transmission is enabled, the DMA receives the data stream sent by the OV2640 from the DCMI interface. First, the Data_Buff1 is used to store the data. When it is full, the DMA switches to the Data_Buff2. At this time, the CPU reads the data in the Data_Buff1 through the wireless network. transmitted to the host computer;

Step 4, when Data_Buff2 is full, the DMA switches to Data_Buff1 for data storage. At this time, the CPU reads the data in Data_Buff2 and transmits it to the host computer through the wireless network.

As shown in Figure 7, the filling of the first buffer area or the second buffer area is controlled by an algorithm, and the DMA data filling algorithm of the present invention is as follows:

Step 1, set the initial value of the buffer size, and set the FIFO buffer of the DMA to transmit 16-bit data at one time, that is, 2 bytes;

Step 2: Divide the buffer size (in bytes) by 2 and round up to calculate the number of times the buffer fills up;

Step 3, compare whether the number of times the buffer is filled exceeds 65535 times, if not, it means that the buffer can be filled only once, and the initial value of the register has been obtained by dividing the size of the buffer by 2;

Step 4. If the number of times of filling the buffer area exceeds 65535, it means that the value of the register loaded once cannot fill the buffer area, then divide by 2, multiply the number of reloads by 2, and then compare the obtained initial value of the register with 65535, and in turn By analogy until the calculated initial value of the register is less than or equal to 65535, the initial value of the MA_SxNDTR register and the number of reloads can be obtained.

Claims (6)

1. A wireless video transmission method for a transformer internal inspection robot is characterized by comprising the following steps:

a. the transformer is internally provided with an internal inspection robot, a lower computer is arranged on the internal inspection robot, an upper computer and a router connected with the upper computer are arranged outside the transformer, the lower computer comprises a core controller, an image acquisition module, a wireless transmission module, a power supply module, a lower storage module and an SDRAM (synchronous dynamic random access memory) module, and the upper computer comprises a control module, a display module and an upper storage module;

b. transplanting the MICO system into a core controller of a lower computer;

c. initializing the MICO system and entering a main program loop;

d. calling a subprogram to initialize the SDRAM;

e. calling the subprogram to carry out wireless network connection, so that a wireless transmission module of the lower computer is connected with the router;

f. calling a subprogram to prepare a memory space of data cache for the image acquisition module, setting a data cache region on the SDRAM, and dividing the data cache region into two cache regions;

g. calling a subprogram to initialize an image acquisition module, and starting a camera to acquire an image;

h. calling a subprogram to create a TCP service thread and waiting for the connection of the upper computer control module and the lower computer through the router;

i. the upper computer is connected with the lower computer, and the data cache region starts a DAM double-cache mode to cache the image data stream from the image acquisition module and starts video transmission.

2. The wireless video transmission method of the transformer internal inspection robot according to claim 1, wherein it is determined whether or not the subprogram returns an error after each subprogram is called, if the subprogram returns an error, state information is output through a serial port, and if the subprogram returns no error, the next subprogram is called; and in the process of creating the TCP service thread subprogram, if the return is correct, outputting the IP address and the port number of the TCP service through the serial port, and waiting for the connection of an upper computer.

3. The wireless video transmission method for the inspection robot in the transformer according to claim 1, wherein the two buffer areas divided in the step f are a first buffer area and a second buffer area respectively; in the step i, after video transmission is started, firstly using a first cache region to store data, when the first cache region is filled, DMA is switched to a second cache region, and the second cache region is used to store the data, at the moment, a CPU of a core controller reads the data in the first cache region and transmits the data to an upper computer through a wireless network; when the second cache region is filled, the DMA is switched to the first cache region, the first cache region is used for storing data, and a CPU (central processing unit) of the core controller reads the data in the second cache region and transmits the data to the upper computer through a wireless network; and continuously repeating the process until the video transmission task is completed.

4. The wireless video transmission method of the transformer internal inspection robot according to claim 1 or 2, characterized in that in step e, the main program calls a WIFI connection network connection subprogram, reads preset parameter values including a router name and a network connection password in an external FLASH, initializes WLAN parameters and a network protocol stack, then performs network connection, and judges whether the connection is successful, if the connection is successful, acquires an IP and a port number of a terminal in a current network, uploads the IP and the port number to an upper computer through a transparent transmission module of a serial port, and if the connection is failed, outputs information of the connection failure through the serial port.

5. The wireless video transmission method of the robot for transformer internal inspection according to claim 1, wherein in step g, a camera subroutine is first invoked to open the camera, configure initialization parameter settings related to interrupt, DMA, and DCMI, configure camera parameters, then restart the camera and read the camera ID, determine whether reading is successful, output error information if reading is unsuccessful, configure the format of the camera output data and the resolution of the output image if reading is successful, set the DCMI camera interface of the core controller to the same format as the camera output, receive data transmitted from the camera mi, start the DCMI continuous image capturing function, enable the DCMI interface, and complete the preparation for video stream transmission.

6. The wireless video transmission method for the inspection robot in the transformer according to claim 3, wherein the data filling algorithm of the DAM is as follows:

setting the loading times of a DMA counter to be 1, calculating the initial value of a counter required by filling a cache region according to the number of bytes transmitted by the DMA once, if the initial value of the required counter is less than or equal to the threshold value of the counter, filling the cache region by loading the counter once, if the initial value of the required counter exceeds the threshold value of the counter, dividing the initial value of the required counter by 2, multiplying the loading times by 2, comparing the new initial value of the counter obtained by dividing the initial value of the required counter by 2 with the threshold value of the counter, and continuously repeating the process until the initial value of the counter is less than or equal to the threshold value of the counter.

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