Backstepping Control for Gear Transmission Servo Systems With Backlash Nonlinearity

The output tracking problem of gear transmission servo (GTS) systems with backlash nonlinearity is studied in this paper. A new concept-“soft degree”-is proposed to overcome the nondifferentiable “hard” characteristic of the backlash nonlinearity. Furthermore, a detailed softening process-static softening is presented, where a backstepping control algorithm is developed to guarantee that the output of the controlled systems can track any given desired sufficiently smooth trajectory by arbitrary precision and the limit cycles that appear due to backlash nonlinearity can be avoided. Simulation results validate the effectiveness of the proposed controller.