Innovating motorsports vehicle and tire testing: Kistler presents new wheel force transducer

From 0 to 100kph in a blistering 2.5 seconds: drivers of racing cars navigate tight corners at breathtaking speeds. The explosive power and rapid acceleration of race cars showcase the pinnacle of engineering, where every detail is meticulously crafted to push the limits of performance and speed. With such intense pressure on both vehicle and tires in motorsport, precise data collection is crucial to prevent tire blowouts, mechanical failures, and accidents. By monitoring tire loads and behavior, engineers can optimize cars ensuring the safety of drivers and spectators alike. Additionally, teams can better adapt their race strategies to maximize their chances of winning. The generated data also provides crucial insights into vehicle dynamics such as balance and stability. By analyzing longitudinal and lateral dynamics, including sideslip and drift angles, manufacturers can fine-tune chassis and control systems like ABS and TC, ensuring stable handling during sudden, highly dynamic drive manoeuvres. 

Understanding the complex dynamics of wheel forces is essential. Only with advanced tools can motorsport teams navigate the intricate balance between speed, safety, and external influences such as track temperature, weather conditions, and aerodynamics. Motivated by the switch from 13-inch to 18-inch wheels in Formula 1 – creating more space for sensors and electronics – Kistler has developed the new RoaDyn Racing wheel force transducer. This self-contained device helps teams optimize race strategies, tire management, weight distribution, tire degradation, and driving dynamics across various race series. It is already being used in the development of the latest generation of GT3 vehicles and has been tested in Formula E since 2021 with a pre-series version.

The RoaDyn Racing WFT is designed with maximum usability in mind, eliminating the need to connect to the vehicle’s onboard system or external transmission modules that could compromise data integrity. The wheel force transducer stores data directly within the measurement device, allowing for quick and easy downloads via USB. In addition, mechanics can use a remote control to start measurement data acquisition from all four wheels simultaneously which simplifies and facilitates work processes. Synchronization with the other measured values is realized by a trigger, which can be operated in both master or slave mode. The internal power is supplied by rechargeable batteries. 

At the heart of this system are four highly precise, temperature-compensated strain gauge load cells that measure forces and moments acting on the wheel of up to 20kN wheel load. These sensors provide critical data on tire loads and tire behavior. The system calculates all force and moment components within a rotating coordinate system, then seamlessly converts them into a non-rotating (fixed wheel) frame by applying the angular functions of the rotating angle. This complex process is handled in real time directly in the wheel force transducer, ensuring instant and accurate data. If required, the system also records individual forces. Precision is further guaranteed through the calibration of the sensors according to ISO 17025, using the Hexapod system from Kistler.

Forged from lightweight magnesium or aluminum alloy structural components, the device is designed for durability and has undergone extensive rotational bending testing with over two million cycles at loads up to 5,000 Nm. It can be used at speeds of up to 360 kph. Its ring-shaped electronics provide unobstructed access to the central nut, while the independent “on the wheel” electronics simplify the installation process – enabling mechanics to install the device in less than 60 seconds. The wheel force transducer’s intuitive design allows teams to handle it correctly within just two hours, thanks to its significantly reduced setup complexity. Kistler also provides detailed instructions and offers support whenever needed, ensuring a seamless user experience. Motorsport applications regularly push engineering to its limits. With RoaDyn Racing, Kistler demonstrates its commitment to innovation, enabling precise measurements even in extreme conditions.