According to a kind of higher order, strong coupling, uncertainty nonlinear system, such as ball and plate system,
a cascade control strategy with low order active disturbance rejection control(ADRC) is presented based on backstepping
design idea. Because the disturbance and coupling are treated as an additional state variable, which is then estimated and
compensated for in real time through the extended state observer(ESO) of low order ADRC, the problems of uncertainty
nonlinear, coupling and disturbance rejection are all resolved. At the same time, the simulation studies of trajectory tracking
with ball and plate system are made. The results show that the proposed strategy has better dynamic, robust characteristics
and adjusts to the higher order, and complicated nonlinear object.