Abstract: The disharmonism of brake system between the travel-trailer and the car is the main reason which has blocked the development of travel-trailer for a long time. The application of electromagnetic brake can solve that problem well. The control system of electromagnetic brake is studied. The brake system can recognize the magnitude of the braking force which the trailer needs by the tiny deform of the joint between trailer and car. Analog signals collected by strain gages are translated into digital signals by A/D board. Computer operates the digital signals with control arithmetic and the result is used to initialize timing/counter board. After being initialized, the 8253 CMOS of timing/counter board can output two routes pulse width modulation (PWM) pulse signals. The signals are exported to metal-oxide-semiconductor (MOS) switch to control the voltage of electromagnetic brake. Then the braking force of trailer can be controlled. Experimentation proves that the control system can adjust trailer’s braking force in time.

Key words: Control system, Electromagnetic brake, Trailer