smart media kiosk for bus stops
In 2018, on the eve of the FIFA World Cup, part of the bus stop pavilions in Kaliningrad was reconstructed. They were supplied with power and advertising light boxes were installed. After the end of the championship, the city administration decided to modernize these advertising structures, adding socially useful information. Won the competition one of the Kaliningrad companiesand we will talk about its development.
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Mini-PC x86, software and vandal-proof kiosk case
An information kiosk is a large monitor behind vandal-proof glass in a durable metal casing. The body was made of structural steel 2–3 mm thick, protected from external conditions by electrodiffusion galvanizing and powder painting, and the base was made of 5 mm steel sheet for additional strength. The cases are produced by a local factory – there are different color options.
Vandal-proof profiled triplex glass 16 mm thick was equipped with a film for touch input. The glass is locally produced and can be athermal (heat-resistant), anti-reflective, or a combination of both. This solution provides a high degree of protection from external influences.
Specialists inside the kiosk Engineering workshop WEND installed a mini-PC based on x86 architecture, which is responsible for outputting video to the monitor. We decided to use standard components in a compact package. We chose our own Linux build as the operating system, so that there was nothing superfluous. Of course, it is more difficult to maintain than popular distributions, but the programmers on staff of the company can easily cope with this.
Programmers have developed a suite of software and databases for performance control and content management, including:
own Linux build and repository for deploying and updating software on computers;
Electron-based player;
personal account for advertisers;
admin panel for managing and analyzing a network of media kiosks;
monitoring system.
Using the software, you can generate and display content generated in advertisers’ personal accounts, synchronize media files between local and cloud storage, and do not depend on the quality of the connection. Most failures are resolved automatically based on monitoring data and using scripts to eliminate potential errors – operator participation in the operation of the entire network of media kiosks is minimal.
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Why do we need media kiosks?
We briefly described what a media kiosk consists of and what software is needed for their operation, but how are they useful for the citizens and guests of Kaliningrad? Media kiosks have a number of useful functions:
Transport information. At the top of the monitor a ticking line is displayed with route numbers and the remaining time until the buses arrive. The data comes from the operator via the API. City residents appreciated the convenience of this function and, when the kiosk was temporarily dismantled for repairs, immediately requested its return. Fortunately, the media kiosk was quickly repaired and returned to its place.
News and Events. The system displays Kaliningrad news from the portal RUGRAD and information about current events in the city.
Advertising. It ensures the return on investment of the project. We have created a personal account for advertisers to manage campaigns.
Tourist navigation. Thanks to the touch panel, tourists can view walking routes, information about flora and fauna, historical data, etc.
In addition, the mini-PC recognizes the image from the kiosk camera. A camera was installed in each kiosk Hikvision. Why is this necessary? As they explained to us, advertising targeting is now being developed. The system will know how many people are at the stop and what age and gender they are. If pensioners are waiting for the bus, you can show advertisements that will be of interest to them. If middle-aged people go to work or return home, different advertising. If the stop is empty, you can lower the screen brightness to save energy and reduce temperature.
The cameras are connected to the Safe City system; they transmit streaming video to servers 24/7. The camera has a local cache, into which it writes a certain amount of data in case the Internet connection fails. If the system detects incidents, it alerts law enforcement, increasing safety at traffic stops.
With the help of such a hardware and software complex, you can view media content in high quality, being next to the media kiosk, in any weather and at any time of the day.
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Industrial monitors and cooling
The monitors are also not quite ordinary. The kiosks use industrial monitors with 4K resolution and an IPS matrix with thermistor properties. Unlike conventional LED panels with large pixels, choosing IPS 4K delivers clear and detailed images – an important advantage for displaying quality content.
Since the kiosks are located outdoors, they require very high brightness – the monitor provides up to 2500 cd/m². At night such brightness is not needed, so after sunset the controller turns on the dark theme and reduces the brightness, and at dawn it does the opposite. A light sensor was built into the kiosk, with the help of which the brightness changes depending on the amount of light on the street. We will return to this later. But how do you adjust the brightness? Engineers abandoned the IR remote control simulation because this solution is not the most reliable. Therefore, we decided to use a special input on the monitor and adjust the brightness using PWM. The analog output module is responsible for this. WB-MAO4.
The downside of high brightness is heat generation. The panel backlight consumes up to 400 W of power. In the new version of the kiosks, engineers not only installed panels with a wider temperature range, but also increased ventilation. They placed four 24V fans at the bottom, which force air into the main segment from the lower chamber. A dust filter was added in front of the fans. Four more fans were installed in the upper part, which extract air from the main segment – each of them consumes up to 14.5 W of power, that is, a total of 120 W. The fans are connected using standard 4-pin plugs to a PWM distributor board, which we developed and manufactured ourselves. Thus, to control each four fans, only one PWM signal is used, which is provided by the module WB-MAO4. The fans provide good cooling, and throughout the entire summer season there have never been any cases of overheating.
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Controller and sensors
To ensure uninterrupted operation of the kiosks 24/7, engineers installed an additional controller for dispatching. In the first version of the kiosks, they decided to use automation equipment from a local manufacturer. But the first year of operation gave a disappointing picture: the controllers turned out to be unreliable. We had to constantly solve various problems: for example, the components inside the kiosk heated up to 60–70 °C – this led to the failure of both the controllers and the Mikrotik router.
That's why we chose Wiren Board controller. I was also impressed by the stated temperature range from -40 to +75 °C. As practice has shown, the controller successfully withstood temperatures up to 70 °C. If the temperature exceeds the 70 °C threshold, the fans operate at full power. If you still can’t cool the system, you have to turn off the monitor.
The new version of the kiosk replaced the Mikrotik router module WBC-4G v.2 with a 4G modem – it was installed directly into the controller case. This solution helped reduce the number of nodes in the system and potential sources of failures. The modem is responsible for connecting to the Internet; The monitoring and administration system works through it. In addition, the controller acts as a router for the computer and camera, which transmits the image to the Safe City APK.
Two sensors were installed in the kiosk 1Wire DS18B20 for temperature control. The first is above the monitor; it is used to regulate the operation of the cooling system. The second is in front of the built-in IR heater for cold starts at the bottom of the main segment. This sensor complements the module WB-MS v.2 on DIN rail for temperature and humidity control. Since kiosks can be installed in cold regions of Russia, cold starts with sub-zero temperatures are possible in winter. Therefore, the Wiren Board controller first turns on the IR heater via a relay module WB-MR6CUheats the main segment of the kiosk and dries it. When conditions become suitable, the controller turns on the computer, camera and monitors. This relay module also controls the audio amplifier and two fan power supplies.
We were interested in a light sensor of our own design. It consists of an analog light sensor, which the engineers connected to the analog input of the Wiren Board controller. They also built in two 1Wire temperature sensors.
In the lower segment of the kiosk, from where fans draw air to cool the main segment, two speakers, batteries and electric machines were installed. Although the current version of the kiosk does not use speakers, it is possible to play audio. For speakers, we developed our own module with an amplifier in a DIN-rail housing. We also installed a self-developed inrush current limiting relay with state detection through the input of the Wiren Board controller. If the city does not supply electricity, the Wiren Board will know about it and send an appropriate alert.
A relay module was added to control some of the loads WB-MRWM2 with power consumption measurement. Using it, you can find out the consumption of the monitor and fans, that is, indirectly determine their status, for example, understand whether the monitor is working and whether the fans are spinning. In one of the kiosks, the monitor was “glitchy”: it turned off the backlight about once a week. Now this condition is easy to determine: there is power, but the power consumption is low. We wrote a script that reboots the monitor based on power supply, and temporarily solved the problem until a full repair was completed.
The developers use Node-RED for programming and wrote all the logic for the controller and modules in it. But in the future they plan to switch to wb-rules scripts.
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Conclusion
Work is in full swing in the assembly shop: by October 2024, they plan to put into operation 50 new kiosks at bus stops. In addition, the design was deliberately made modular: the standard kiosk is one-sided, but it can be easily converted into a two-sided one by adding a monitor on the other side, an x86 computer and a Wiren Board controller with modules.
Projects for installing similar kiosks in nature reserves are now also being considered. In these conditions, the touch functions of the panel will be especially in demand for the interactive interaction of visitors with information about routes, flora, fauna and historical features of the area.
How do you rate the development? Engineering workshop WEND? Are there any ideas to improve the project? Perhaps you would like to share your own experience and developments? Write in the comments.
