Sensor Technology
Knowing the limit: measuring tyre grip before it matters
Aleksandr Timofeev, CEO of POLYN Technology, discusses how direct, real-time measurement of tyre-road friction could improve braking, stability control and ADAS performance by giving vehicle systems access to accurate grip data before wheel slip occurs
CIE: What critical input is missing from today’s vehicle control systems? Aleksandr Timofeev (AT): Vehicle control has advanced through brake-by-wire, individual wheel torque control, and improved sensing of speed, motion, and position. One critical input is still generally missing: the grip available between each tyre and the road. This grip limit determines how much braking, acceleration, or cornering force the vehicle can produce. Without direct measurement, controllers must rely on assumptions. If they assume too much grip, a tyre can exceed its limit on a slippery surface. If they assume too little, the vehicle gives up performance unnecessarily. In ideal conditions, stopping distance is inversely related to friction, so a surface with half the grip can require roughly twice the braking distance.
CIE: What is the Peak Friction AT: The Peak Friction Coefficient, or PFC, represents the physical grip limit between a tyre and the road. A tyre has a limited friction force budget, and braking, acceleration, and cornering all draw on the same capacity. The available friction force can be expressed as F = PFC × Fz, where Fz is the vertical load. A measured PFC value gives controllers a clearer view of the size of that force budget at each tyre.
CIE: Why do conventional friction estimates arrive too late? AT: Most existing systems calculate friction from wheel slip during braking or acceleration. The estimate becomes reliable only when a tyre is already approaching its grip limit. At steady driving, ice and dry asphalt can both produce very little slip, leaving the system with limited evidence of the difference. It may therefore rely on the last significant event even if that event occurred much earlier and on another surface.
22 October 2026
CIE: Why is per-tyre information important? AT: An average vehicle-level value is insufficient when the wheels encounter different surfaces, such as when one side crosses ice, standing water, or a painted road marking. During braking, unequal grip can pull the vehicle into a turn. Per tyre, PFC allows the system to increase pressure on the high-grip side, reduce it earlier on the low-grip side, and prepare to correct the resulting yaw. The same information can help all-wheel-drive and torque vectoring systems distribute power without first causing wheelspin.
CIE: Which vehicle functions could use measured PFC? AT: The signal can support ABS and electronic braking systems, electronic stability control, traction control, transmission and all-wheel- drive management, adaptive cruise control, autonomous emergency braking, and automated driving. These systems already have the actuators and computing capacity to use a friction input; what they generally lack is direct, timely information about the grip available at each wheel.
CIE: How does VibroSense TMS from POLYN assess grip? AT: Continuous assessment from tyre vibration during normal rolling provides grip information before the vehicle reaches the limit. VibroSense TMS evaluates the vibration generated at the tread-road interface. A compact analogue neuromorphic chip processes the accelerometer signal inside the tyre and derives a PFC value from 0.1 to 1.2. The node transmits the result rather than a continuous stream of raw vibration data. This reduces radio transmission and power demand to a level sufficient for a battery- powered TPMS-type node.
Components in Electronics
CIE: Why does knowing PFC before braking improve ABS performance? AT: When ABS begins a stop without reliable friction information, it must search for the correct operating point by increasing brake pressure, observing wheel response, and then adjusting. This short learning period consumes valuable distance at the beginning of the stop, when vehicle speed is highest. If PFC is available at the start, the controller can select a more appropriate initial pressure and slip target from its first cycle. This does not predict a future surface; it removes the delay in identifying the condition already under the tyre.
CIE: How could ABS and electronic braking systems use it? AT: ABS and EBS can use PFC to select a better slip target for each tyre. On a split- friction surface, they can manage the two sides differently before wheel-lock behaviour reveals the problem. This is the application tested to date. Commercial vehicles could benefit from the same principle, particularly because changing loads introduce additional uncertainty.
CIE: How could stability and powertrain systems use it? AT: Electronic stability control can use measured PFC to interpret the vehicle’s expected response more accurately and
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