Research On Coordinated Control Strategy Of Automobile Electro-Mechanical Brake Booster And ABS

Environmental pollution and energy crisis force traditional cars to transform to new energy vehicles,intelligent and networking trends promote the transition from traditional cars to smart cars.These changes put forward new requirements for the brake system:(1)New energy vehicles eliminate the engine or the engine can’t provide enough vacuum,and we need to find new ways to deal with it;(2)Intelligent vehicles was controlled actively and accurately in real time,and this requires active brake function with quick response and precise adjustment;(3)The braking energy recovery function requires constant pedal feeling;(4)Various braking modes need variable brake boost characteristics.The new brake system consisting of an electromechanical brake booster and an electronic stability control system meets these new requirements.Through cooperation with an automotive parts company,this paper carried out the following researches about the experimental platform construction,mechanism analysis and characteristic testing,control strategy research and verification,etc.:(1)System structure determination and test bench setup.The overall scheme of the electromechanical brake boost system was proposed.Based on the self-developed EMBB,an electric cylinder test bench and a hardware-in-loop test bench were constructed,including software part and hardware part.(2)Systematic analysis and characteristic test.The vacuum booster operating characteristics were analyzed and tested to determine the EMBB basic power assist control target.The force coupling characteristics of the EMBB rubber feedback disk were analyzed and tested to obtain the principle of servo force adjustment based on the displacement difference of the feedback disk.The adjustment characteristics of a certain ABS product on different attachment surfaces and the operating characteristics of the Bosch i Booster systemwere tested to determine the coordination goals of EMBB and ABS.(3)Research and verification of EMBB basic power control strategy.Determined whether EMBB achieves the maximum assist power,designed servo force saturation control and servo displacement follow-up control,and controlled the motor current.Based on the electric cylinder test bench,the basic control strategy was effective under different input speed and displacement that obtain the same assistance characteristic as vacuum booster.(4)Research and verification of EMBB and ABS coordinated control strategy research.For the uncoordinated problems between EMBB and ABS,based on the requirements of the brake wheel cylinder,the three-closed-loop coordinated control architecture of the master cylinder pressure ring,servo displacement ring and motor current ring was determined.Switching logic of basic power control strategy and coordinated control strategy was designed.With the hardware-in-loop test bench,this coordinated strategy was verified effectively in typical ABS roadway environment.In summary,the research in this paper has achieved a certain system function,which provides a reference for the future development of electronic mechanical system and control strategy.