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

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 for a transformer internal inspection robot.

Background

In the operation and maintenance of the present power equipment, the transformer not only belongs to one of the most important and expensive equipment in the power system, but also belongs to one of the equipment causing more accidents in the power system, and the reliability of the transformer is directly related to whether the power grid can be operated safely, efficiently and economically. According to the requirement of maintenance regulations of large-scale power transformers, the suspension cover maintenance is required to be carried out once every 5 years, and the internal inspection method of removing the suspension cover has the advantages of accurate and thorough fault finding, but has the defects of very high inspection cost, long construction period and the like in the field. The method is a revolutionary change in transformer maintenance if useful information in the transformer can be obtained without lifting and unpacking. Due to the fact that the internal environment of the transformer is complex, the interior of the container has good tightness, the traditional wired transmission mode is difficult to achieve, and information acquired by the transformer internal inspection robot inside the transformer, particularly video information, is difficult to transmit to the external environment.

How to transmit video information acquired by an internal inspection robot in a transformer to the external environment is a key problem which needs to be solved urgently.

Disclosure of Invention

The invention aims to provide a wireless video transmission method for a transformer internal inspection robot, which aims to solve the problem that video information acquired by the transformer internal inspection robot in a transformer is difficult to transmit to the external environment.

The invention is realized by the following steps: a wireless video transmission method for a transformer internal inspection robot comprises 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.

After each subprogram is called, whether the subprogram returns an error or not is judged, 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.

The two cache regions divided in the step f are respectively a first cache region and a second cache region; 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.

In the step e, calling a WIFI connection network connection subprogram by a main program, reading a parameter value preset in an external FLASH, including a router name and a network connection password, initializing a WLAN parameter and a network protocol stack, then carrying out network connection, judging whether the connection is successful, if the connection is successful, acquiring the IP and the port number of the terminal in the current network, uploading 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, outputting the connection failure information through the serial port.

In step g, a camera subprogram is called to open the camera, interrupt, DMA and DCMI related initialization parameter setting are configured, camera parameters are configured, then the camera is restarted and a camera ID is read, whether reading is successful or not is judged, error information is output if reading is failed, the format of data output by the camera and the resolution of an output image are configured if reading is successful, a DCMI camera interface of a core controller is set to be the same as the format of the data output by the camera, data transmitted by the camera is received, a DCMI continuous image capturing function is started, the DCMI interface is enabled, and transmission preparation of a video stream is completed.

The data-filling algorithm of 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.

The invention enters the transformer through the internal inspection robot to acquire and process images, then transmits data to the upper computer through a wireless network, and the upper computer displays image information acquired by the lower computer, thereby realizing wireless real-time transmission of videos inside the transformer. 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. In order to ensure that the MICO system can stably run on a core controller, a SDRAM chip is added. The invention uses DAM double-buffer mode to buffer data, DAM is responsible for filling data buffer area, CPU is responsible for network data transmission, realizes parallel operation of data acquisition and output, and greatly reduces load of processor.

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

Drawings

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

Fig. 2 is a video transmission flow diagram 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 image acquisition of the present invention.

Fig. 5 is a flow chart of the TCP transport service of the present invention.

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

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

Detailed Description

The invention comprises 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.

As shown in fig. 1, the present invention first provides a video transmission system for a robot for transformer internal inspection, which includes an upper computer, a lower computer and a router. The upper computer is a software air control center of the wireless transmission system and used for resolving the video data transmitted by the lower computer terminal. The lower computer is a video acquisition terminal and is in wireless connection with the upper computer, the internal environment of the transformer is detected in real time, and video information is transmitted to the upper computer, so that the internal inspection of the transformer is realized.

Wherein, the host computer includes:

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

the display module is used for displaying the video information transmitted by the lower computer in real time;

and the upper storage module is used for storing the received information.

The lower computer comprises:

the core controller is specifically an STM32F429IGT6 single chip microcomputer and is responsible for driving the image acquisition module to acquire and process images;

the image acquisition module is connected with the core controller through a DAMI interface specific to an STM32F4 series single chip microcomputer, and is used for acquiring image information of the internal environment of the transformer in real time;

the wireless transmission module is connected with the main control chip through an SDIO interface and is used for carrying out remote data transmission communication between the upper computer and the lower computer;

the power supply module comprises a conversion module and supplies power to the core controller, the wireless transmission module and the image acquisition module;

and the SDRAM module IS an external SDRAM chip expanded by an STM32F4 series single chip microcomputer and used for caching data, and the specific model IS IS42S 16400J.

The wireless transmission module of the SDIO interface selects a WIFI module of the SDIO interface, a data transmission mode of converting serial ports into WIFI is adopted for a traditional WIFI module, the speed of the WIFI module is only the transmission speed of a common serial port, the WIFI module is suitable for occasions with less data and low real-time performance, the data transmission speed of the WIFI module of the SDIO interface can reach 24MB at most, and the requirement of video transmission speed is met.

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

step 1, preparing a MiCOKit suite, Keil5 development software and related hardware equipment;

step 2, distributing storage space, and dividing FLASH into a BootLoader area, an Application area and an RF firmware area;

step 3, transplanting the BootLoader, adding a new hardware platform in the MiCOKit, and modifying corresponding codes according to the parameters of the lower computer terminal hardware to enable the BootLoader to be matched with the terminal hardware;

and 4, transplanting the Application, selecting the Application program to be transplanted according to the actual Application, wherein the transplanting Application is similar to the new project and comprises the configuration of relevant parameters such as file creation, chip type selection, head file path selection, FLASH storage space distribution and the like.

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

step 1, after a lower computer terminal is powered on, external equipment lines such as a MiCO system and peripherals are initialized under the control of a main control chip, wherein the initialization mainly comprises configuration of SPI, SDIO, USART and a watchdog;

step 2, after initialization is completed, the system enters a main program cycle to initialize the SDRAM, whether the SDRAM initialization is normal is judged through an API subprogram provided by the MiCO system, and if the subprogram initialization is wrong, the main program outputs related information through a serial port;

step 3, after the SDRAM is initialized, judging whether the WIFI chip is connected to a specified wireless network or not through a subprogram return value, and outputting relevant information of a connection state by a serial port regardless of whether the equipment is successfully connected to a router or not;

step 4, preparing a memory space of data cache for the camera, establishing two data buffer arrays, clearing the cache, and acquiring the address of a cache region so as to write video stream data in the subsequent process;

and 5, calling a subprogram to initialize the camera, wherein the initialization comprises the initialization of a camera interface, the configuration of the output format of the camera and other related parameter settings.

And 6, creating a TCP service thread, judging whether the subprogram has errors by the main program, outputting error information by the serial port if the subprogram has errors, and outputting the IP address and the port number of the TCP service by the main program if the subprogram has no errors. At this time, the lower computer terminal becomes a TCP server to wait for the connection of the remote user, namely the upper computer control terminal, and provides the video transmission service.

And in the running process of the main program, judging whether the subprogram returns an error or not after each subprogram is called, if the subprogram returns an error, outputting state information through a serial port, and if the subprogram returns no error, calling the next subprogram.

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

step 1, a lower computer control main program calls a WIFI network connection subprogram, and a structure body array is created to store parameters required by wireless network connection;

step 2, reading preset parameter values of the external FLASH, including the router name and the network connection password;

step 3, initializing WLAN parameters, and setting WIFI chip related parameters including channel selection, a security mode, a station or AP mode, waiting time required by connection failure and reconnection trying time;

step 4, initializing a network protocol stack;

and 5, connecting the network, judging whether the connection is successful, and if the connection is successful, acquiring the current network IP and the port number of the terminal by the program and uploading the current network IP and the port number to the upper computer through the external transparent transmission module of the serial port. If the connection fails, the information of the connection failure is output through the serial port.

As shown in fig. 4, the present invention uses JPEG compression coding format as the output format of the data collected by the camera, and configures and uses the camera by calling the camera subprogram in the main program, and the steps include:

step 1, calling a camera subprogram to configure and open a camera;

step 2, entering subprogram configuration interruption, DMA and DCMI related initialization parameter settings including clock, GPIO, working mode and the like;

step 3, configuring camera parameters, initializing a camera SCCB bus, and verifying whether the MCU and the camera can normally communicate;

step 4, restarting the camera, reading the ID number of the camera, and judging whether the reading is successful or not by comparing the ID number with ID information provided by an official;

step 5, configuring the format of the data output by the camera;

step 6, setting the resolution of the image output by the camera;

step 7, setting a DCMI camera interface of the core controller into a JPEG format, and receiving data transmitted by a camera;

step 8, setting the DCMI interface to be in a continuous capture mode for data reception;

and 9, enabling the DCMI interface, and enabling the lower computer to acquire images to transmit video streams with the upper computer.

As shown in fig. 5, the TCP transmission service flow of the present invention is as follows:

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

step 2, reading a local IP address and a preset port number of the WLAN connection, and creating a socket;

step 3, binding the obtained IP address and the port number;

step 4, after the operation is completed, the server enters a monitoring state to wait for a handshake request sent by an upper computer;

step 5, after the connection is successful, the terminal starts video acquisition;

and 6, reading data from the cache region by the TCP server thread, transmitting the data to an upper computer through a wireless network, and displaying the acquired video information after decoding the data by the upper computer software.

When carrying out video transmission, read out data from the camera, all need pass through WIFI chip transmission again after the processing of CPU of core control ware and storage at every turn, can lead to the load greatly increased of treater like this, if use DMA double cache mode buffer memory data just can be fine this problem of solution, wherein DMA is responsible for filling the data buffer, and CPU is responsible for the transmission of network data, has just so realized the parallel operation of data acquisition with output. The invention applies a double-cache mechanism to cache the collected video data, and designs a cache filling related algorithm of the DMA of the STM32F4 series single chip microcomputer, thereby realizing the online adjustment of the size of the terminal cache region.

As shown in FIG. 6, the DMA double cache mode of the present invention is as follows:

step 1, a Data acquisition end expands an 8MB SDRAM to be used as a Data buffer, and the Data acquisition end is divided into two 4MB buffers which are respectively a first buffer Data _ Buff1 and a second buffer Data _ Buff2 due to the use of a double-buffer mechanism.

Step 2, starting a DMA double-cache mode on the STM32F429, setting the DBM bit of the register DMA _ SxCR to be 1, and then automatically activating a circulation mode by a DMA controller;

step 3, after starting video transmission, the DMA receives the Data stream sent by the OV2640 from the DCMI interface, firstly, Data _ Buff1 is used for storing Data, after the Data stream is fully filled, the DMA is switched to Data _ Buff2, and at the moment, the CPU reads the Data in the Data _ Buff1 and transmits the Data to the upper computer through a wireless network;

and step 4, when the Data _ Buff2 is fully filled, the DMA is switched to the Data _ Buff1 for Data storage, and at the moment, the CPU reads the Data in the Data _ Buff2 and transmits the Data to the upper computer through the wireless network.

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

step 1, setting an initial value of the size of a cache region, and setting a FIFO cache of a DMA to transmit 16-bit data at one time, namely 2 bytes;

step 2, dividing the size of the cache region (taking bytes as a unit) by 2 to calculate the times required by the full filling of the cache region;

step 3, comparing whether the number of times of filling the cache region exceeds 65535, if not, indicating that the cache region can be filled only once, and the initial value of the register is obtained by dividing the size of the cache region by 2;

step 4, if the number of times of filling the buffer area exceeds 65535, it indicates that the value of the register loaded once cannot fill the buffer area, then divide by 2, multiply the number of times of reloading by 2, then compare the obtained initial value of the register with 65535, and so on until the calculated initial value of the register is less than or equal to 65535, so as to obtain the initial value of the MA _ sxntnr register and the number of times of reloading.

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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