Challenging ambient conditions for mobile robots: "Rain or dust are no problem for our sensors"

Expert interview with Juan Velasco Durán, AGV Industry Manager at SICK in Spain

Extreme sunlight or rain outdoors, plus dust and vibrations in production or logistics - the ambient conditions for mobile robots such as Automated Guided Vehicles (AGVs) and Autonomous Mobile Robots (AMRs) are challenging and can change abruptly, for example when leaving a hall. Nevertheless, their sensors must work reliably at all times to enable safe and efficient operation. Juan Velasco Durán, AGV Industry Manager at SICK in Spain, tells us in our expert interview how this is achieved and what it has to do with cycling.

Juan, what are the challenges of environmental changes for mobile robots?

Juan: I'm an avid cyclist and this basically compares: The weather changes from bright sun to rain, the ground is suddenly bumpy, or it's blinding after a tunnel. On the bike, you can't be prepared for everything, but our sensors are designed for many of these changes by default. For everything else, there are suitable accessories.

How does this help mobile robots and AGVs cope with such stresses?

Juan: The sensors have to function at both high and low temperatures and must not be irritated by dust, fog or vibrations. First of all, this is ensured by a reliable casing that is insensitive to shock and completely sealed. Incidentally, vibrations are also a problem for load handling because the goods could be damaged. That's why safety encoders are needed that continuously provide information about position, angle, and number of revolutions. With the help of a suitable control solution, the AGV then reacts accordingly to fluctuations and unevenness.

What about changing visibility conditions?

Juan: Even if the lens is dirty or fogged up, or if the light intensity is high, the right technology can help to deliver reliable measurement data. Up to 80,000 lux is then no problem for safety laser scanners such as the nanoScan3 thanks to safeHDDM®. This acronym stands for "safe High Definition Distance Measurement" and is a high-resolution digital method for time and distance measurement. It offers particularly high optical ruggedness - interference is simply filtered out by an algorithm.

And what if the dirt on the lens gets out of hand?

Juan: That cannot be prevented in individual cases. However, modern sensors can indicate this in good time before their functionality is impaired. This is made possible by integrated contamination measurement of the optics cover. Condition monitoring or predictive maintenance solutions even make it possible to detect contamination in good time - and to take countermeasures early on.

Is rain a bigger problem?

Juan: In heavier rain, a solution we call airWiper helps. It simply blows the water droplets away with compressed air. Up to 30 millimeters of precipitation can be withstood without any problems. To go back to the example from the beginning, in this situation, cyclists need a rain jacket- and that's the big difference: When using this technology, you don't have to change either vehicle or equipment, so a seamless supply chain is ensured.

As well as this, how can AGVs respond to such weather changes?

Juan: After all, high availability is very important for operating entities. One way to achieve this is for AGVs not to stop in poor measurement conditions, but then just to slow down. This not only reduces weather-related interruptions, but also protects brakes and mechanics. For this to succeed, the safety laser scanner must be able to automatically switch its protective fields depending on the weather, enabling continuous operation even in heavy rain or snowfall. This is exactly what our Dynamic Weather Assist safety system does. It consists of the outdoorScan3 safety laser scanner, the Flexi Soft safety controller, and a software function block.

Are there also areas where, conversely, a higher speed is desired?

Juan: Yes, this is often the case indoors, for example in transit zones between charging stations with little traffic and simple ambient conditions. Here, ambient detection in the millimeter range is usually not required. Consequently, 3D radar sensors can be used to significantly expand the aperture angle and thus enable higher speeds even in difficult weather conditions. Therefore, it always comes down to an intelligent combination of sensor technologies.

The development of mobile robots is often very customer-specific. How do manufacturers arrive at the optimum combination?

Juan: First of all, it's helpful if a wide variety of sensors is available, i.e. a kind of modular system for all requirements. And then it's a matter of providing precisely tailored advice that addresses individual needs and possibilities. This is exactly what we have done in a large number of projects with various customers. We have designed and implemented the systems in close cooperation with the engineering and research & development departments to achieve a customized solution.

What are the usual challenges in projects of this kind?

Juan: In one of our first projects of this kind, the challenge was to develop a vehicle that is maneuverable both indoors and outdoors and can even travel long distances on roads that are difficult to negotiate. To find the right solutions for this mixed operation, we first conducted tests and a long-term study in which we evaluated different 2D LiDAR sensors, digital services for condition monitoring, and the aforementioned outdoorScan3. In the process, we defined protective fields that permanently monitor the environment. Their measurement data ensures reliable operation during loading and unloading - almost regardless of the ambient conditions. As a cyclist, let me put it in a nutshell: There is no bad weather for us, only bad equipment.

One last question: Have requirements changed in recent years and where is the trend heading?

Juan: The entire field of mobile platforms and robots is increasingly dynamic. This applies to both regulatory requirements and user requirements, in terms of changing environments. So, it's more important than ever to respond quickly to these changes. To do this, you first have to understand exactly what the customer wants and, develop a suitable solution accordingly. That's why, on the one hand, very close cooperation with our customers is so important to us. On the other hand, we regularly invest more than 10% of our sales in research and development. This is a very high value and it expresses our self-image: Our future lies in the future viability of our customers.