Friction Circle Diagram

Deep dive

Segers explains in Analysis Techniques for Racecar Data Acquisition: "The friction circle is a way of thinking about not only the grip that a vehicle can develop under given conditions but also how this grip is being utilized by the driver. The positive side of the Y-axis indicates that the vehicle is accelerating; the negative side means that it's braking. The negative X-axis means that the car is cornering to the right and vice versa. The area covered by the data points represents the acceleration envelope of the vehicle." He adds a powerful diagnostic use: "The friction diagram is a good tool for the engineer to get an idea about the general direction of the car setup. The highest accelerations seen in the diagram give a rough idea about the importance of aerodynamic downforce. The density of the point cloud in every quadrant can give the engineer an indication about the effectiveness of asymmetric geometry settings." A sparse friction circle means the driver is spending too much time in transitions rather than at the limit.