Method and apparatus for controlling speed of autonomous vehicle

An apparatus for controlling a speed of an autonomous vehicle, comprising:

• a sensor unit for measuring a speed of a wheel of the vehicle;
• a control unit for controlling the speed of the vehicle by generating a driving signal or a braking signal;
• and
• a torque applying unit for applying wheel torque to the wheel based on the driving signal or the braking signal,
• wherein the control unit configured to calculate a slip ratio based on the speed of the wheel, determine a road surface condition from a plurality of road surface conditions, based on a correlation among the plurality of road surface conditions, the wheel torque, and the slip ratio, determine a maximum speed of the vehicle based on the determined road surface condition, and control the speed of the vehicle not to exceed the maximum speed,
• the determined road surface condition is classified according to a friction coefficient of the road surface,
• the wheel torque is braking torque or driving torque applied to the wheel, and
• when the speed of the vehicle is below the maximum speed, the control unit is configured to increase the speed of the vehicle to the maximum speed and then maintain the speed of the vehicle at the maximum speed.