Measurement of new hall zero-magnetic flux type of the quenching hardness for a machine element

The principle of measuring the quenching-hardness for the machine elements is the Hall zero-magnetic flux type of principle (i.e. a closed-loop principle), and the formula of the steady-state error for the Hall zero-magnetic flux system is deduced, and the conclusion that the larger the amplifier amplification in the Hall zero-magnetic flux system, the smaller the steady-state error is reached.