The Fraunhofer IVV Dresden is developing a mobile cleaning device that uses an optical sensor system to detect dirt and thus the cleaning requirements of systems. It then determines the cleaning parameters individually and carries them out autonomously. To do this, the Mobile Cleaning Device (MCD) is moved through the machine on the conveyor belt. In this way, the researchers combine the flexibility of manual cleaning processes with the advantage of reproducible results from automated cleaning-in-place (CIP) systems. This saves the user time, conserves resources and at the same time makes the processes more reproducible - also thanks to sensors and industrial cameras from Baumer.

Developing new cleaning technologies that can also be used in hygienically sensitive areas of food and pharmaceutical production is a central focus of research at the Fraunhofer IVV in Dresden. "In most cases, current cleaning processes are designed for the worst-case scenario, which means that a lot of time and resources are wasted," says Roman Murcek, project manager for the MCD at the Fraunhofer IVV. The industry's interest in automated systems for needs-based, contactless and intelligent cleaning is therefore great - also in order to be able to validate cleaning results better and on a large scale. This is because hygiene is a decisive factor in food production in particular, with a direct impact on food safety. Where is the contamination located, what type is it and what are the appropriate cleaning media? Was the cleaning successful? These are questions that people have to answer and evaluate in manual processes and which are often only validated on a random basis and locally, for example using swab tests.

Degree of soiling determines cleaning

The MCD individually adjusts the intensity of cleaning to the degree of contamination of the processing equipment, making results reproducible and thus increasing food safety. (Image: Fraunhofer IVV Dresden)

The idea for the first prototype of the MCD came about as part of the EU "PicknPack" project to develop a flexible and modular packaging system. "Our task was to develop a cleaning system. However, due to the modularity of the system, the integration of a conventional CIP system was not expedient," explains Murcek. A mobile, flexible cleaning device that cleans all surfaces of the systems that come into contact with the product in a hygienic manner without the risk of cross-contamination was the obvious solution.

Today, the MCD is equipped with seven nozzles that can apply different cleaning media such as water or foam at up to 10 bar, depending on the type and degree of soiling. In the processing plants, it follows the product path and is moved through the machine on the existing conveyor system. For other cleaning tasks without a conveyor belt, the developers have designed a self-propelled system. Here, either an additional module is used or motors and wheels are mounted directly on the cleaning device. While moving through the object to be cleaned, the MCD emits UV light to detect the usually fluorescent organic dirt particles, such as grease residues, using a camera. "In most cases, we generate the best contrasts with the UV light used, as the excitation produces hardly any visible light components," says Murcek. The MCD cleans according to the registered soiling and spatial dimensions, for example by foaming heavily soiled areas more intensively. Each nozzle can be controlled individually. Cleaning media, water pressure and temperature can thus be varied and also used precisely to achieve the best result. After pre-rinsing, foaming and rinsing, the appliance checks and records the cleaning result. The MCD receives the control signals via WLAN and is powered by rechargeable batteries. "The only physical interface is a hose for supplying the cleaning medium," explains Murcek. This is connected to a supply station and feeds the MCD with water and foam or other cleaning media through the same nozzles without any changeover.

Its design makes the MCD flexible for use in different systems and increases food safety. Compared to manual cleaning processes carried out by humans, it works more efficiently, reliably and reproducibly. "It can also clean areas that a person cannot easily reach without dismantling parts of the machine," says Murcek. The researchers also expect significant time savings. Initial cleaning tests by the Fraunhofer IVV have also shown that around 20 percent of cleaning media can already be saved compared to conventional CIP systems. Finally, the image processing used enables seamless quality control and documentation of the cleaning process.

With optics and sensors against dirt

At the heart of the optical system's hardware for detecting dirt and cleaning as required is a GigE camera from the CX series with 5 megapixels. "We have been using Baumer cameras in various test rigs for years, for example to monitor and quantify cleaning processes or to detect soiling on surfaces. Based on our positive experience, we have also opted for Baumer for the MCD," says Murcek. Good image quality and high light sensitivity of the camera are important for the detection of weakly fluorescent soiling under UV light. With a resolution of 5 megapixels, the camera is also ideal for detecting small contaminated areas in a large image area without any loss of information. Image analysis is currently carried out via Matlab and Labview thanks to third-party compatibility.