SMART BRAKES Self-diagnosis of intelligent brake pads
Acceleration is essential, but braking is even more critical. The Darmstadt Fraunhofer Institute for Structural Durability and System Reliability LBF and its partners have researched intelligent brake pads with integrated sensors that enable self-diagnosis.
Those who can rely on their brakes feel safe in traffic. It would be even more pleasant if the brake pads would continuously report how fit they still are. Experts from the SME 4.0 Competence Centre in Darmstadt of the Fraunhofer Institute for Structural Durability and System Reliability LBF have researched how to implement smart friction materials in cooperation with LF GmbH & Co KG from Leverkusen. In an implementation project, they integrated sensors into brake pads to obtain information on the operating status based on downstream data processing and enable the pads to perform self-diagnosis. Thanks to this integration, data from inside the friction lining can determine the layer thickness and the wear condition. In the long term, it should be possible to train self-optimizing brake systems and draw conclusions about brake pressure, friction values, braking torques, and the brake system's control behavior.
Making brakes intelligent
The Leverkusen-based LF GmbH & Co. KG develops and produces innovative friction materials for industrial clutches and brake linings. In contrast to established technologies, the particular type of production allows the manufacture of "intelligent" friction linings, made from the liquid phase and pressureless in a low-temperature range (RT-120°C). As part of the implementation project, the experts first selected suitable sensors, which they contacted before the manufacturing process, and then integrated into the liquid phase. In this way, the sensors could supply data from inside the friction lining, which was determined both before and after braking operations and during extensive brake tests.
Even the pre-tests showed how sensitive the integrated sensor technology was to external loads and pressure changes. By integrating several sensors in one brake pad, the team could also identify conditions of unequal pressure distribution in the brake pad. By measuring the vibration characteristics of the sensors in conjunction with the friction lining, the experts were also able to make statements about the friction lining layer thickness. "This will enable the evaluation algorithm used to assess the wear condition of the friction linings in the future and detect damage caused by changes in the stiffness of the friction layer. In the long term, we see the possibility of teaching self-optimizing brake systems with such information," explains Jonas Martin Brandt. He is in charge of the project in the SME 4.0 Competence Centre Darmstadt of the Fraunhofer LBF.
Identifying and improving the behavior of brake or clutch applications
In final tests on a brake test stand, the researchers exposed the brake pads sensors to the loads and temperatures typical for braking processes. The interactions of different brake pressures with the brake hydraulics were analyzed so that the experts could determine the optimum force application for the various pressure ranges. "In the future, conclusions beyond the actual brake lining will be possible due to the embedded sensor technology. In this way, the typical behavior of brake or clutch applications can be identified and improved if necessary," predicts Brandt.
The positive results of the project open up opportunities for industrial applications. In the next step, the experts will investigate the extent to which it is possible to determine parameters and information that cannot be directly measured using corresponding AI algorithms. Another sensor technology is suitable for integration in corresponding friction linings.