Tham khảo tài liệu 'tyre vehicle dynamics episode 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | APPLICATIONS OF TRANSIENT TYRE MODEL 401 and B for predicting when braking should be reduced to prevent the wheel from locking. Thus we have from the starting of brake application Increase of torque for 0 t tB according to dA g dí The preliminary prediction time tA is given by 1 reOã tA -Tg where reo stands for the nominal effective rolling radius and T for a constant which sets the treshold for Q. From time tB we have Decrease of torque for tB t tc according to dA g dí 2 The instant of prediction and action tB is defined by _ reo WJ - Wb TSStB - ỳ AVB The time tc marks the beginning of the constant torque phase CE . Constant torque for tc t tE . ảMB dt 0 Time tc is found from Q tc 0 Similarly the criterion for increasing the torque at E Increase of torque for t tE according to dA g dt Rị is given by the compound reselection conditions generated at points D and E with tD and tE being found from w 0 and reo ổ y-ổ ổ y- -y AVE For the simulation the following values have been used T -1 A VB reo Q tB and A VE 1 m s The brake torque rates have been set to Rx -R2 19000Nm s In order to simulate the braking manoeuvre of a quarter vehicle equipped with the anti-lock braking system the deceleration of the vehicle is taken to be proportional to Fx. The results of the simulations performed are presented in . The left-hand diagrams refer to the case of braking on an ideally flat road while the diagrams on the right-hand side depict the results obtained with the same system on a wavy road surface. For the purpose of simulation the model was extended to include a hydraulic sub-system interposed between the brake pedal and the wheel cylinder. However this extension is not essential to our discussion. In both cases the same hydraulic sub-system was used and the same control algorithm as the one discussed above was implemented. The further parameters used in the simulation were Initial speed of the vehicle 60 km h the road input with a wavelength of m and an .
