Functional model
Safety Sensor Demonstrator
for safe distance measurement

The trade fair demonstrator, with over 3,000 installed LEDs, attracts the attention of trade fair visitors and illustrates the operating principle of safe distance measurement using a doubly implemented radar measurement path. Preprogrammed games and mechanically adjustable sensors invite visitors to discover the advantages of radar technology interactively.

For safe distance measurement, two sensor pairs, each consisting of two opposite radar sensors, form a self-monitoring measurement system. When the two lower sensors move in parallel, they deliver matching and thus valid distance values. If the difference between the measured values is too large, an alarm is automatically triggered and the system is immediately brought to a safe state.

The LPR®-1DHP-291 sensors from SYMEO are used in demanding industrial environments where high robustness and reliability are critical, for example in dust, dirt and extreme weather conditions.

One example is use in shipyards. Mounted on the crane bridge, the sensors precisely detect and monitor the crane position during loading of container ships and ensure the safety of people and equipment under extreme conditions.

To liven up the atmosphere at the trade fair booth, two interactive games and an Easter egg were programmed into the functional model:

In the first game, inspired by “Beer Pong,” the aim is to throw a virtual ball into a “cup” of markings with a sensor movement - fingertip control is required!

In the second game, “Space Egg,” the player controls a hen (sensor marker) and must position it above an egg (color strip) to hatch it. Whoever manages to hatch their chick first (color change of the strip from red to green) wins.

The Easter Egg reveals a beautiful rainbow running light that flows like falling drops of color from top to bottom. It is activated when the sensors are moved against each other for several seconds.

To ensure smooth production of the trade fair model, the entire model was designed in detail in 3D.

The construction of the LED tube posed a special challenge: an aluminum tube that simultaneously serves as a support for the LEDs, a ventilated heatsink, and a cable channel gives the column the necessary stability. In addition, two acrylic tubes acting as diffusers were integrated to softly spread the LED light. With this combination, both functional and aesthetic requirements had to be met.

The perfect interplay of microelectronics and custom-made mechanics.

Hidden in the base of the functional model is the powerful control electronics that processes the sensor signals and also controls the LED tubes. The heart is an ESP32 dual-core 32-bit microcontroller that is programmed in C++ and produces impressive LED effects at up to 120 FPS. The radar sensors are connected via Ethernet through a CISCO switch.

A plain bearing from Igus enables smooth movement of the sensor in the Z direction and reliably prevents twisting around its own axis.

The thoughtful combination of two tension springs holds the sensor precisely in the center position. One spring carries almost the entire self-weight of the sensor, while the second spring catches the remaining weight force only from the center position onward by its preload. In this way, despite bearing friction and manufacturing tolerances, an exactly defined middle rest position is achieved.

In two acrylic tubes of the functional model, a total of 3,000 LEDs of the WS2812 ECO type were installed for displaying measured values and light effects. The energy-efficient LEDs are connected in a daisy-chain, allowing all RGB LEDs to be driven in groups with only a few data lines from a single ESP32 microcontroller.

A cooling system with high-quality Noctua PC fans generates a constant airflow inside the tubes and the base. This reliably cools the power supplies and LEDs, ensuring long-lasting performance.

All components with complex geometries were produced on a Bambu Lab X1E 3D printer. The carbon-fiber reinforced filament used, PAHT-CF (high-temperature resistant nylon), is particularly resilient and withstands high loads.

To ensure the highest fit accuracy and minimize rework, all required wooden parts of the functional model were CNC-produced and could be mounted directly with precise fit.

A transport box specially designed for the functional model ensures quick assembly/disassembly and offers optimal protection during transport of the valuable exhibition object.

Behind the scenes, work was done with passion and creativity. The development and construction of the functional model were a perfect combination of software, electronics, and hardware. From precise CAD design through manufacturing by CNC and 3D printing to programming in C++, I was able to contribute everything that makes my engineer's heart beat faster. Especially the programming of the LED effects left much room for creativity and made the project a real highlight.

Already during manufacturing and especially after completion, the functional model provided an excellent opportunity to fully indulge my passion for photography and videography. The individual steps of the production process as well as the impressive light effects made the project a fascinating subject for the camera.

... for the SYMEO team at the exhibition booth.

Many thanks to the exhibition team of Symeo GmbH from Munich for the trusting and appreciative collaboration. Especially the friendly and cordial personal contact as well as the creative freedom granted during implementation made this project a thoroughly enriching experience. A valuable cooperation that was positive in every respect.

At the SPS trade fair in Nuremberg the functional model draws attention. With fascinating LED lighting effects and interactive games, it invites trade fair visitors to explore the world of radar technology in a playful way.