Stability Analysis And Control Strategy Of United Braking System Of Heavy Equipment Transporters

With the rapid development of national economy, heavy equipment transporters which as a combination of tractor and semi-trailer,the usage and production of it cause attention of all aspects,especially of braking safety performance. Now, the relevant safety standards carried out by our country stipulate that heavy equipment transporters must install auxiliary brakes, with higher braking torque,hydraulic retarder becomes the best choice for the heavy equipment transporters. But the hydraulic retarder have to install on transmission shaft that is the rear axle of tractor, which may effect the original braking force distribution of heavy equipment transporter. In this paper, the stability of united braking system were studied and figured out the control strategy which improve the stability of heavy equipment transporter.Firstly, the phase-plane of united braking system including side-slip angle phase-plane of tractor and semitrailer and articulated angle phase-plane were explored,the result of it shows that when retarder at 1st and 2nd gear, the stability of the heavy equipment transporter is good; when retarder at 3rd gear, tractor is to unstable and semi-trailer is unstable; when retarder at 4th gear, heavy equipment transporter is unstable.Secondly, considered about the braking initial speed, road adhesion coefficient and semi-trailer’s load also affect the phase-plane, high, medium and low braking initial speed and road adhesion coefficient and full, half-full and empty load of semi-trailer were studied, the result shows the braking initial speed and road adhesion coefficient do have impact of the stability of united braking system.Thirdly, the boundary of articulated angle phase-plane at every braking initial speed and road adhesion coefficient were defined, then the boundary of articulated angle phase-plane were determined.Fourthly, in order to study the control strategy, the dynamic model used Trucksim which have much experiments of heavy equipment transporter were established including vehicle body, the steering system, the tire system, the braking system(without hydraulic retarder), the suspension system, the powertrain system and the aerodynamic systems. The retarder model was established via simulink to Trucksim. Then the intergalactic model of heavy equipment transporter were finished.Finally, the four kinds of braking state were defined: slight braking, emergency braking, conventional braking and constant braking, considered the control strategy ofconventional braking and constant braking, verified feasibility of the strategy used Trucksim-simulink united simulation.