Question:
How to design a wireless video and data transmission system for a pipe inspection robot using Raspberry Pi, VTX, and RFD868?
I am working on a pipe inspection robot that can travel up to 500 meters inside metal pipes with diameters ranging from 152 mm to 203 mm. I need to transmit the video feed from a web camera attached to the robot, as well as the control data for the robot’s actuators and sensors. I have some experience with electronics, but I am not an expert.
I have tried using a Wi-Fi based system with two Raspberry Pis, one as a transmitter and one as a receiver, and a web server hosted on the local network. However, this system had poor performance and reliability, as the video feed was laggy or lost beyond 20 meters, and the receiver Pi had difficulty connecting to the Wi-Fi network.
To overcome these limitations, I am considering using a different system based on the following components:
- A Raspberry Pi as the video transmitter, which will process the web camera input using OpenCV and add some sensor data overlays, and then output the video signal through the composite video port.
- A 5.8 GHz VTX (video transmitter) module with 1 W of power, which will receive the video signal from the Raspberry Pi and transmit it wirelessly. I have the RUSHFPV RUSH TANK II 5.8GHz VTX W/ Smart Audio module, but I am also interested in the AKKA 3W VTX module, which has higher power output and might be more suitable for long-range transmission.
- A 5.8 GHz VRX (video receiver) module, which will receive the wireless video signal from the VTX and display it on a monitor or a screen.
- A RFD868 radio module, which will be used for bidirectional data transmission between the robot and the controller. The RFD868 module will be connected to a STM32 microcontroller, which will communicate with the Raspberry Pi and the robot’s actuators and sensors using USART. The STM32 microcontroller will be programmed using the stmduino method. I have read the datasheet and the user manual of the RFD868 module, but I am not sure how to use the AT commands and whether the module will send plain serial data or not.
- A RFD868 radio module, which will be used as the data receiver and will be connected to another STM32 microcontroller, which will act as the controller for the robot.
Based
on this system design, I have the following questions for an expert:
– Will this system be able to transmit the video and data signals up to 500 meters through a metal pipe with a diameter of 152 mm to 203 mm? – Will this system be reliable and robust, or will it suffer from interference, noise, or signal loss? – Will the quality of the video feed from the VTX be acceptable, or will it be degraded or distorted? – Can the RFD868 module be used for controlling the robot up to 500 meters and will it send plain serial data that can be easily processed by the STM32 microcontroller? – Is this project feasible and realistic, or are there any major challenges or drawbacks that I have overlooked? – Are there any better alternatives for the RFD868 module, such as the LoRa E32-900T30D module, which I have tested and found to work well up to 250 meters in an open road environment?
Answer:
Pipe inspection is an important task for ensuring the safety and efficiency of pipelines that transport water, oil, gas, or other fluids. However, pipe inspection can also be challenging, especially when the pipes are long, narrow, or located in harsh environments. Therefore, pipe inspection robots are often used to perform this task, as they can travel inside the pipes and collect various data, such as images, videos, temperature, pressure, corrosion, etc.
However, designing a wireless video and data transmission system for a pipe inspection robot is not a trivial task, as it involves several technical and practical issues, such as the choice of components, the signal range and quality, the interference and noise, the power consumption and supply, the data format and protocol, the reliability and robustness, etc.
In this article, we will discuss a possible system design for a pipe inspection robot that can travel up to 500 meters inside metal pipes with diameters ranging from 152 mm to 203 mm. We will use a Raspberry Pi as the video transmitter, a 5.8 GHz VTX module as the wireless video transmitter, a 5.8 GHz VRX module as the wireless video receiver, a RFD868 module as the bidirectional data transmitter and receiver, and a STM32 microcontroller as the data processor and controller. We will also address some of the questions and challenges that arise from this system design.
System Components and Design
The system consists of two main parts: the robot and the controller. The robot is the device that travels inside the pipe and collects the video and data signals, while the controller is the device that receives and displays the video and data signals and sends the control commands to the robot. The following diagram shows the system components and design:
“` +—————–+ +—————–+
| | | |
| Controller | | Robot |
| | | |
| | | |
| STM32 + RFD868 |<--->| STM32 + RFD868 |
| | | |
| | | |
| VRX + Monitor |<----| VTX + RasPi + |
| | | Camera + Sensor |
+—————–+ +—————–+ “`
The robot has the following components:
- A Raspberry Pi as the video transmitter, which will process the web camera input using OpenCV and add some sensor data overlays, and then output the video signal through the composite video port. The Raspberry Pi is a small and affordable computer that can run various software and applications, such as OpenCV, which is a popular library for computer vision and image processing. The Raspberry Pi can also communicate with other devices using various interfaces, such as GPIO, USB, UART, etc.
- A 5.8 GHz VTX (video transmitter) module with 1 W of power, which will receive the video signal from the Raspberry Pi and transmit it wirelessly. The VTX module is a device that converts the analog video signal into a radio frequency signal and broadcasts it over a certain channel and bandwidth. The VTX module can have different power levels, which affect the signal range and quality. The higher the power, the longer the range and the better the quality, but also the higher the power consumption and the heat generation. We have chosen the RUSHFPV RUSH TANK II 5.8GHz VTX W/ Smart Audio module, which has a power range from 0.01 W to 1 W and supports 48 channels and 6 bands. This module also has a smart audio feature, which allows us to change the settings of the VTX module remotely using the RFD868 module and the STM32 microcontroller. Alternatively, we could use the AKKA 3W VTX module, which has a higher power output of 3 W and might be more suitable for long-range transmission, but also has a higher power consumption and heat generation.
- A web camera as the video source, which will capture the images and videos inside the pipe and send them to the Raspberry Pi. The web camera can be any USB camera that is compatible with the Raspberry Pi and has a suitable resolution and frame rate for the video feed. The web camera should also have a small size and a flexible cable, so that it can fit inside the pipe and move along with the robot.
- A sensor as the data source, which will measure the temperature, pressure, corrosion, or other parameters inside the pipe and send them to the Raspberry Pi. The sensor can be any analog or digital sensor that is compatible with the Raspberry Pi and has a suitable accuracy and range for the data measurement. The sensor should also have a small size and a robust design, so that it can withstand the harsh conditions inside the pipe.
- A STM32 microcontroller as the data processor and controller, which will receive and send the data signals from and to the RFD868 module and process them accordingly. The STM32 microcontroller is a powerful and versatile microcontroller that can run various programs and algorithms, such as PID control, Kalman filter, etc. The STM32 microcontroller can also communicate with other devices using various interfaces, such as GPIO, USB, UART, etc. The STM32 microcontroller will be programmed using the stmduino method, which is a way of using the Arduino IDE and libraries to program the STM32 microcontroller. This method makes it easier and faster to write and upload the code to the STM32 microcontroller, as well as to use the existing Arduino libraries and functions.
- A RFD868 radio module as the bidirectional data transmitter and receiver, which will receive and send the data signals wirelessly from and to the robot. The RFD868 module is a long-range and high-speed radio module that operates at the 868 MHz frequency band and supports various data rates and modulation schemes. The RFD868 module can have different power levels, which affect the signal range and quality. The higher the power, the longer the range and the better the quality, but also the higher the power consumption and the heat generation. The RFD868 module can also be configured using the AT commands, which are a set of instructions that can be sent to the module using the USART interface to change the settings, such as the frequency, the data rate, the power level, etc. The RFD868 module can also send and receive plain serial data, which can be easily processed by the STM32 microcontroller.
- A 5.8 GHz VRX (video receiver) module, which will receive the wireless video signal from the robot and display it on a monitor or a screen. The VRX module is a device that receives the radio frequency signal from the VTX module and converts it back into an analog video signal. The VRX module can have different sensitivity levels, which affect the signal quality and noise. The higher the sensitivity, the better the quality and the lower the noise, but also the higher the power consumption and the heat generation. The VRX module should also match the channel and the bandwidth of the VTX module, so that they can communicate properly. We have chosen the RUSHFPV RUSH BLADE F722 5.8GHz VRX W/ Smart Audio module, which has a sensitivity range from -90 dBm to -120 dBm and supports 48 channels and 6 bands. This module also has a smart audio feature, which allows us to change the settings of the VRX module remotely using the RFD868 module and the STM32 microcontroller.
- A monitor or a screen as the video display, which will show the video feed from the robot. The monitor or the screen can be any device that has a composite video input port and a suitable resolution and size for the video display. The monitor or the screen should also have a clear and bright display, so that we can see the details and the colors of the video feed.
The controller has the following components:
System Questions and Challenges
Based
on this system design, we have the following questions and challenges that we need to address:
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