Development of NHRI-4000 high performance with large contact surface direct shear apparatus

The development of NHRI-4000 high performance direct shear apparatus with large contact surface is introduced. The control precision requirements of normal force and shear force are achieved by use of the digital PID fuzzy control method. Mcs51 microcontroller control unit and multi-machine communication are used to control the normal force and shear force. Low-pass filter of the circuit and other techniques of the hardware circuit and a simple moving average technique in software are used to ensure the stability of the signal. The software programmed by Delphi language has the capability of automatic collection and real-time graphics by means of spcomm controls and timing controls.