The united brake which is used by heavy vehicles can’t get the maximum braking force.Aimming at this problem

ABS is combined with the united brake

μ-s mode based on the Kiencke is used to identify the status of road by recursive least squares combing forget factor automatically and quickly

and in order to get the best slip ratio

the curve shape of μ-s is used to identify the suddenly change of road’s status in the process of braking.Simulation experiment proves that the united brake which based on ABS can achieve the maximum braking force and shorten braking time.