A system for maintaining near-peak friction of a wheel/ground interface during a braking operation of a wheeled vehicle, the system comprising: a slip detector configured to determine wheel slip based on a difference between ground speed and rotation speed of the wheel; a volatility calculator configured to calculate a measure of volatility of the wheel slip based on a high-frequency component of the determined wheel slip; and a brake controller configured to generate a brake control signal for transmission to a brake mechanism of the wheel based, at least in part, on the calculated measure of volatility; the system being characterized in that it further comprises a perturbation summer configured to: receive a high-frequency perturbation signal; and add the high-frequency perturbation signal to the generated brake control signal so as to cause the brake mechanism to dither braking power; wherein the brake controller is configured to compare the calculated measure of volatility with a predetermined volatility target; and wherein the brake control signal generated by the brake controller is configured to cause the brake mechanism to decrease the braking power if the calculated measure of volatility is greater than the predetermined volatility target, or wherein the brake control signal generated by the brake controller is configured to cause the brake mechanism to increase the braking power if the magnitude of the calculated measure of volatility is less than the predetermined volatility target. a slip detector configured to determine wheel slip based on a difference between ground speed and rotation speed of the wheel; a volatility calculator configured to calculate a measure of volatility of the wheel slip based on a high-frequency component of the determined wheel slip; and a brake controller configured to generate a brake control signal for transmission to a brake mechanism of the wheel based, at least in part, on the calculated measure of volatility; the system being characterized in that it further comprises a perturbation summer configured to: receive a high-frequency perturbation signal; and add the high-frequency perturbation signal to the generated brake control signal so as to cause the brake mechanism to dither braking power; wherein the brake controller is configured to compare the calculated measure of volatility with a predetermined volatility target; and wherein the brake control signal generated by the brake controller is configured to cause the brake mechanism to decrease the braking power if the calculated measure of volatility is greater than the predetermined volatility target, or wherein the brake control signal generated by the brake controller is configured to cause the brake mechanism to increase the braking power if the magnitude of the calculated measure of volatility is less than the predetermined volatility target. receive a high-frequency perturbation signal; and add the high-frequency perturbation signal to the generated brake control signal so as to cause the brake mechanism to dither braking power; wherein the brake controller is configured to compare the calculated measure of volatility with a predetermined volatility target; and wherein the brake control signal generated by the brake controller is configured to cause the brake mechanism to decrease the braking power if the calculated measure of volatility is greater than the predetermined volatility target, or wherein the brake control signal generated by the brake controller is configured to cause the brake mechanism to increase the braking power if the magnitude of the calculated measure of volatility is less than the predetermined volatility target.